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Sample records for microwave-assisted photocatalytic degradation

  1. Enhanced photocatalytic degradation of methylene blue by ZnO-reduced graphene oxide composite synthesized via microwave-assisted reaction

    Lv Tian [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Pan Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China); Liu Xinjuan; Lu Ting; Zhu Guang; Sun Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai, 200062 (China)

    2011-10-13

    Highlights: > ZnO-reduced graphene oxide composite is synthesized via microwave assisted reaction. > The method allows a facile, safe and rapid reaction in aqueous media. > A high dye degradation efficiency is achieved under UV light irradiation. - Abstract: A quick and facile microwave-assisted reaction is used to synthesize ZnO-reduced graphene oxide (RGO) hybrid composites by reducing graphite oxide dispersion with zinc nitrate using a microwave synthesis system. Their photocatalytic performance in degradation of methylene blue is investigated and the results show that the RGO plays an important role in the enhancement of photocatalytic performance and the ZnO-RGO composite with 1.1 wt. % RGO achieves a maximum degradation efficiency of 88% in a neutral solution under UV light irradiation for 260 min as compared with pure ZnO (68%) due to the increased light absorption, the reduced charge recombination with the introduction of RGO.

  2. Rapid synthesis of Ti-MCM-41 by microwave-assisted hydrothermal method towards photocatalytic degradation of oxytetracycline.

    Chen, Hanlin; Peng, Yen-Ping; Chen, Ku-Fan; Lai, Chia-Hsiang; Lin, Yung-Chang

    2016-06-01

    This study employed microwave-assisted hydrothermal method to synthesize Ti-MCM-41, which are mesoporous materials with a high surface area and excellent photocatalytic ability. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) were employed. The XRD findings showed that Ti-MCM-41 exhibited a peak at 2θ of 2.2°, which was attributed to the hexagonal MCM-41 structure. The BET (Brunauer-Emmett-Teller) results agreed with the TEM findings that Ti-MCM-41 has a pore size of about 3-5nm and a high surface area of 883m(2)/g. FTIR results illustrated the existence of Si-O-Si and Si-O-Ti bonds in Ti-MCM-41. The appearance of Ti 2p peaks in the XPS results confirmed the FTIR findings that the Ti was successfully doped into the MCM-41 structure. Zeta (ζ)-potential results indicated that the iso-electric point (IEP) of Ti-MCM-41 was at about pH3.02. In this study, the photocatalytic degradation of oxytetracycline (OTC) at different pH was investigated under Hg lamp irradiation (wavelength 365nm). The rate constant (K'obs) for OTC degradation was 0.012min(-1) at pH3. Furthermore, TOC (total organic carbon) and high resolution LC-MS (liquid chromatography-mass spectrometry) analyses were conducted to elucidate the possible intermediate products and degradation pathway for OTC. The TOC removal efficiency of OTC degradation was 87.0%, 74.4% and 50.9% at pH3, 7 and 10, respectively. LC-MS analysis results showed that the degradation products from OTC resulted from the removal of functional groups from the OTC ring. Copyright © 2016. Published by Elsevier B.V.

  3. Preparation of silver-modified TiO2 via microwave-assisted method and its photocatalytic activity for toluene degradation

    Li Xiaobin; Wang Linling; Lu Xiaohua

    2010-01-01

    Silver-modified TiO 2 (Ag-TiO 2 ) with various Ag/Ti molar ratios were prepared by the microwave-assisted method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and UV-vis diffuse reflectance spectroscopy (UV-vis-DRS). Compared with the hydrothermal method, Ag-TiO 2 of small crystallite size and high crystallinity can be obtained by the microwave-assisted preparation method. When the Ag/Ti molar ratio increased from 0 to 2%, the doping of Ag promoted the phase transformation and inhibited the growth of anatase crystallite. The absorption edge of Ag-TiO 2 shifted to longer wavelength, and the band gap energy of Ag-TiO 2 decreased. However, after increasing the molar ratio Ag/Ti further from 2 to 4%, the anatase content, the crystallite size and the band gap energy of Ag-TiO 2 only increased slightly. In photodegradation gaseous toluene, the photocatalytic activity of Ag-TiO 2 increased with the increase of Ag/Ti molar ratio from 0 to 1%, but declined with the further increase to 2%. The optimal Ag/Ti molar ratio for photocatalytic activity of Ag-TiO 2 was found as 1%, with the content of anatase, rutile and brookite of 71.1, 14.5 and 14.4%, respectively. Compared with TiO 2 , Ag-TiO 2 exhibited a better photostability in toluene degradation.

  4. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO{sub 4} composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

    Yan, Yan [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Sun, Shaofang [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Song, Yang; Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Guan, Weisheng [School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Liu, Xinlin [School of Material Science and Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China)

    2013-04-15

    Highlights: ► Microwave-assisted in situ growth of RGO-BiVO{sub 4} composite was proposed. ► A relatively small particle size with organic-additives free. ► Graphene was formed during the microwave-heating by oxygen capture. ► GB-2 sample exhibits the highest CIP degradation ratio (3 times over pure BiVO{sub 4}). ► The enhancements of activities result from the effective charge separation. -- Abstract: To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO{sub 4} composite photocatalysts. The as-produced RGO-BiVO{sub 4} composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO{sub 4} photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO{sub 4} composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO{sub 4} particles. The enhancement of photocatalytic activities of RGO-BiVO{sub 4} photocatalysts can be attributed to the effective separation of electron–hole pairs rather than the improvement of light absorption.

  5. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    Li, Tingting; Luo, Shenglian; Yang, Lixia

    2013-01-01

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O 2 · − , Br 0 and photogenerated h + play key roles in the photocatalytic degradation process

  6. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin.

    Yan, Yan; Sun, Shaofang; Song, Yang; Yan, Xu; Guan, Weisheng; Liu, Xinlin; Shi, Weidong

    2013-04-15

    To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron-hole pairs rather than the improvement of light absorption. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

    Darwish, Maher; Mohammadi, Ali; Assi, Navid

    2016-01-01

    Highlights: • PVP-stabilized CdS nanoparticles have been fabricated by a polyol-microwave method. • CdS nanoparticles were characterized and the size was approximately 48 ± 10 nm. • Catalytic activity of our nanoparticles was examined for tartrazine degradation. • Remarkable results were obtained under both UV and visible light irradiations. - Abstract: Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.

  8. Microwave-assisted polyol synthesis and characterization of pvp-capped cds nanoparticles for the photocatalytic degradation of tartrazine

    Darwish, Maher, E-mail: m-darwish@razi.tums.ac.ir [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mohammadi, Ali, E-mail: alimohammadi@tums.ac.ir [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Assi, Navid, E-mail: navid_a30@yahoo.com [Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2016-02-15

    Highlights: • PVP-stabilized CdS nanoparticles have been fabricated by a polyol-microwave method. • CdS nanoparticles were characterized and the size was approximately 48 ± 10 nm. • Catalytic activity of our nanoparticles was examined for tartrazine degradation. • Remarkable results were obtained under both UV and visible light irradiations. - Abstract: Polyvinylpyrrolidone capped cadmium sulfide nanoparticles have been successfully synthesized by a facile polyol method with ethylene glycol. Microwave irradiation and calcination were used to control the size and shape of nanoparticles. Characterization with scanning electron microscopy revealed a restricted nanoparticles growth comparing with the uncapped product, hexagonal phase and 48 nm average particle size were confirmed by X-ray diffraction, and finally mechanism of passivation was suggested depending on Fourier transform infrared spectra. The efficiency of nanoparticles was evaluated by the photocatalytic degradation of tartrazine in aqueous solution under UVC and visible light irradiation. Complete degradation of the dye was observed after 90 min of UVC irradiation under optimized conditions. Kinetic of reaction fitted well to the pseudo-first-order kinetic and Langmuir–Hinshelwood models. Furthermore, 85% degradation of the dye in 9 h under visible light suggests that cadmium sulfide is a promising tool to work under visible light for environmental remediation.

  9. Photocatalytic perfermance of sandwich-like BiVO{sub 4} sheets by microwave assisted synthesis

    Liu, Suqin, E-mail: liusuqin888@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Xiangyang 441053 (China); Tang, Huiling; Zhou, Huan [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Dai, Gaopeng, E-mail: dgp2000@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Wang, Wanqiang [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China)

    2017-01-01

    Graphical abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO{sub 4} sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO{sub 4}. • The sandwich-like BiVO{sub 4} sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N{sub 2} adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO{sub 4} sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO{sub 4} sheets can be attributed to its large surface area over the irregular BiVO{sub 4} particles.

  10. Photocatalytic perfermance of sandwich-like BiVO_4 sheets by microwave assisted synthesis

    Liu, Suqin; Tang, Huiling; Zhou, Huan; Dai, Gaopeng; Wang, Wanqiang

    2017-01-01

    Graphical abstract: Sandwich-like BiVO_4 sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO_4 sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO_4. • The sandwich-like BiVO_4 sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO_4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N_2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO_4 sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO_4 sheets can be attributed to its large surface area over the irregular BiVO_4 particles.

  11. Microwave-assisted degradation of acid orange using a conjugated polymer, polyaniline, as catalyst

    Ufana Riaz

    2014-01-01

    Full Text Available Microwave-assisted photocatalytic degradation of dyes is one of the emerging technologies for waste water remediation. Microwave effectively accelerates photocatalytic degradation, when microwave electrodeless lamp (MEL substitutes traditional UV lamp as light source. This setup can be extremely simplified if MEL and photocatalyst can be replaced by a catalyst which can work under microwave irradiation in the absence of any light source. The present work reports for the first time degradation of acid orange 7 (AO under microwave irradiation using polyaniline (PANI as catalyst in the absence of any UV lamp as light source. The degradation/decolourization was carried out in neutral acidic and basic media and was monitored spectrophotometrically to evaluate the ability of microwave irradiation to degrade AO. Microwave irradiation showed excellent performance as it completely decolourizes AO dye solution in 10 min. With the advantages of low cost and rapid processing, this novel catalyst is expected to gain promising application in the treatment of various dyestuff wastewaters on a large scale.

  12. Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

    Makama, A. B., E-mail: abmakama@hotmail.com; Salmiaton, A., E-mail: mie@upm.edu.my; Choong, T. S. Y., E-mail: csthomas@upm.edu.my; Abdullah, N., E-mail: nhafizah@upm.edu.my [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia); Saion, E. B., E-mail: elias@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia)

    2016-07-06

    Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl{sub 2} and Na{sub 2}S) in the presence of fixed amount of ZnCO{sub 3} nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-C{sub t}/C{sub 0}) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

  13. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO3 photocatalyst and its photocatalytic activity under simulated solar light

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-01

    Simulated solar light responsive Ag/AgCl/WO 3 composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV–Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO 3 nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: ► Successful synthesis of Ag/AgCl/WO 3 nanocomposite. ► Photocatalytic experiment was performed under simulated solar light. ► Nanocomposite photocatalyst was very active as compared to WO 3 commercial powder. ► SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  14. Urchin-like CdS/ZrO2 nanocomposite prepared by microwave-assisted hydrothermal combined with ion-exchange and its multimode photocatalytic activity

    Li, Li; Wang, Lili; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi; Dong, Xue

    2014-12-01

    A series of urchin-like CdS/ZrO2 nanocomposites with different mole ratios of Cd/Zr were prepared by a two-step method combining the microwave-assisted hydrothermal and ion exchange methods. The products were characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption measurements. The results of the study revealed that the CdS/ZrO2 nanocomposites had mixed phases of tetragonal ZrO2 and hexagonal CdS. Moreover, the samples prepared by the microwave-assisted hydrothermal method possessed the urchin-like structure with a surface composed of protrude-like nanoparticles in large quantities. The absorption in the visible region changed slightly with increasing mole ratio of Cd/Zr. Moreover, compared to the nanocomposites prepared by the conventional heating, the nanocomposites prepared by the microwave-assisted hydrothermal synthesis showed significantly different Brunauer-Emmett-Teller values, and the urchin-like CdS/ZrO2 structures were obtained. The photocatalytic degradation of methyl orange under ultraviolet (UV) light irradiation indicated that the photocatalytic activity of the CdS/ZrO2 nanocomposite with CdS/ZrO2 molar ratio of 30 % was higher than those of CdS, ZrO2, and other different ratios of CdS/ZrO2 nanocomposites. Moreover, under UV light, visible light, and microwave-assisted multimode photocatalytic degradation, the urchin-like CdS/ZrO2 nanocomposites significantly affected the photodegradation of various dyes. To understand the possible reaction mechanism of the photocatalysis by the CdS/ZrO2 nanocomposites, a series of controlled experiments were performed, and the stability and reusability of the CdS/ZrO2 nanocomposites were further investigated by the photocatalytic reaction.

  15. Urchin-like CdS/ZrO2 nanocomposite prepared by microwave-assisted hydrothermal combined with ion-exchange and its multimode photocatalytic activity

    Li, Li; Wang, Lili; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi; Dong, Xue

    2014-01-01

    A series of urchin-like CdS/ZrO 2 nanocomposites with different mole ratios of Cd/Zr were prepared by a two-step method combining the microwave-assisted hydrothermal and ion exchange methods. The products were characterized by X-ray diffraction, ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N 2 adsorption–desorption measurements. The results of the study revealed that the CdS/ZrO 2 nanocomposites had mixed phases of tetragonal ZrO 2 and hexagonal CdS. Moreover, the samples prepared by the microwave-assisted hydrothermal method possessed the urchin-like structure with a surface composed of protrude-like nanoparticles in large quantities. The absorption in the visible region changed slightly with increasing mole ratio of Cd/Zr. Moreover, compared to the nanocomposites prepared by the conventional heating, the nanocomposites prepared by the microwave-assisted hydrothermal synthesis showed significantly different Brunauer–Emmett–Teller values, and the urchin-like CdS/ZrO 2 structures were obtained. The photocatalytic degradation of methyl orange under ultraviolet (UV) light irradiation indicated that the photocatalytic activity of the CdS/ZrO 2 nanocomposite with CdS/ZrO 2 molar ratio of 30 % was higher than those of CdS, ZrO 2 , and other different ratios of CdS/ZrO 2 nanocomposites. Moreover, under UV light, visible light, and microwave-assisted multimode photocatalytic degradation, the urchin-like CdS/ZrO 2 nanocomposites significantly affected the photodegradation of various dyes. To understand the possible reaction mechanism of the photocatalysis by the CdS/ZrO 2 nanocomposites, a series of controlled experiments were performed, and the stability and reusability of the CdS/ZrO 2 nanocomposites were further investigated by the photocatalytic reaction

  16. Study of photocatalytic activities of Bi2WO6 nanoparticles synthesized by fast microwave-assisted method

    Phu, Nguyen Dang; Hoang, Luc Huy; Chen, Xiang-Bai; Kong, Meng-Hong; Wen, Hua-Chiang; Chou, Wu Ching

    2015-01-01

    We present a study of photocatalytic activities of Bi 2 WO 6 nanoparticles synthesized by fast microwave-assisted method. The photocatalytic activities of the nanoparticles were evaluated by the decolorization of methylene-blue under visible-light-irradiation. Our results show that the surface area of Bi 2 WO 6 nanoparticles plays a major role for improving photocatalytic activity, while visible-light absorption has only a weak effect on photocatalytic activity. This suggests efficient transportation of photo-generated electrons and holes to the oxidation active sites on the surface of nanoparticles, indicating Bi 2 WO 6 nanoparticles synthesized by fast microwave-assisted method are promising for achieving high photocatalytic activity under visible-light-irradiation. - Highlights: • The Bi 2 WO 6 nanoparticles were synthesized via fast microwave-assisted method. • The obtained Bi 2 WO 6 nanoparticles exhibited visible-light absorbance. • The surface area of Bi 2 WO 6 nanoparticles plays major role for improving photocatalytic activity. • The Bi 2 WO 6 nanoparticles are promising for achieving high photocatalytic activity under visible-light-irradiation

  17. Degradation of atrazine by microwave-assisted electrodeless discharge mercury lamp in aqueous solution.

    Ta, Na; Hong, Jun; Liu, Tingfeng; Sun, Cheng

    2006-11-02

    The present study investigates the degradation of atrazine (2-chloro-4-(ethyl amino)-6-isopropyl amino-s-triazine) in aqueous solution by a developed new method, namely by means of a microwave-assisted electrodeless discharge mercury lamp (MW-EDML). An experimental design was conducted to assess the influence of various parameters: pH value, initial concentration, amount of EDML, initial volume and coexisted solvent. Atrazine was degraded completely by EDML in a relatively short time (i.e. t(1/2)=1.2 min for 10 mg/l). Additionally, the identification of main degradation products during atrazine degradation process was conducted by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This study proposes the degradation mechanism including four possible pathways for atrazine degradation according to the degradation products.

  18. Microwave-assisted synthesis of NiS2 nanostructures for supercapacitors and cocatalytic enhancing photocatalytic H2 production

    Pang, Huan; Wei, Chengzhen; Li, Xuexue; Li, Guochang; Ma, Yahui; Li, Sujuan; Chen, Jing; Zhang, Jiangshan

    2014-01-01

    Uniform NiS2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H2 production. Different morphologies of NiS2 nanostructures show different electrochemical and cocatalytic enhancing H2 production activities. Benefited novel nanostructures, NiS2 nanocube electrodes show a large specific capacitance (695 F g-1 at 1.25 A g-1) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS2 nanospheres show highly cocatalytic enhancing photocatalytic for H2 evolution, in which the photocatalytic H2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H2 production rate of 283 μmol h-1.

  19. [Microwave assisted UV electrodeless discharge lamp photochemical degradation of 4-chlorophenol in aquatic solutions].

    Ai, Zhi-hui; Jiang, Jun-qing; Yang, Peng; Zhou, Tao; Lu, Xiao-hua

    2004-07-01

    A microwave assisted UV electrodeless discharge lamp system (MW/UV) was used for photo-degradation of 4CP simulated wastewater. In order to evaluate the degradation efficiency of 4CP, UV spectrophotometry and ion chromatography were used for determination of 4CP and Cl- respectively. The degradation rate in MW/UV system was higher than that in the UV system within 120min, which were 52.40% and 21.56% respectively. The degradation efficiency was improved by increasing pH value of the solution, aerating O2 gas, enhancing light intensity, or adding H2O2 oxidant. The degradation of 4CP under MW/UV accords with the first order kinetics equation.

  20. Study of photocatalytic activities of Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method

    Phu, Nguyen Dang [Faculty of Physics, Hanoi National University of Education, 136 Xuanthuy, Cau Giay, Hanoi (Viet Nam); Hoang, Luc Huy, E-mail: hoanglhsp@hnue.edu.vn [Faculty of Physics, Hanoi National University of Education, 136 Xuanthuy, Cau Giay, Hanoi (Viet Nam); Chen, Xiang-Bai, E-mail: xchen@wit.edu.cn [School of Science and Laboratory of Optical Information Technology, Wuhan Institute of Technology, Wuhan 430205 (China); Kong, Meng-Hong [School of Science and Laboratory of Optical Information Technology, Wuhan Institute of Technology, Wuhan 430205 (China); Wen, Hua-Chiang; Chou, Wu Ching [Department of Electrophysics, National Chiao Tung University, Hsin-Chu 30010, Taiwan (China)

    2015-10-25

    We present a study of photocatalytic activities of Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method. The photocatalytic activities of the nanoparticles were evaluated by the decolorization of methylene-blue under visible-light-irradiation. Our results show that the surface area of Bi{sub 2}WO{sub 6} nanoparticles plays a major role for improving photocatalytic activity, while visible-light absorption has only a weak effect on photocatalytic activity. This suggests efficient transportation of photo-generated electrons and holes to the oxidation active sites on the surface of nanoparticles, indicating Bi{sub 2}WO{sub 6} nanoparticles synthesized by fast microwave-assisted method are promising for achieving high photocatalytic activity under visible-light-irradiation. - Highlights: • The Bi{sub 2}WO{sub 6} nanoparticles were synthesized via fast microwave-assisted method. • The obtained Bi{sub 2}WO{sub 6} nanoparticles exhibited visible-light absorbance. • The surface area of Bi{sub 2}WO{sub 6} nanoparticles plays major role for improving photocatalytic activity. • The Bi{sub 2}WO{sub 6} nanoparticles are promising for achieving high photocatalytic activity under visible-light-irradiation.

  1. Preparation of highly photocatalytic active CdS/TiO{sub 2} nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis

    Li, Li, E-mail: qqhrll@163.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Key Laboratory of Composite Modified Material of Colleges in Heilongjiang Province, Qiqihar 161006 (China); Wang, Lili [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Hu, Tianyu [College of Environment and Resources, Jilin University, Changchun 130024 (China); Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China)

    2014-10-15

    CdS/TiO{sub 2} nanocomposites were prepared from Cd and Ti (1:1 M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6 h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N{sub 2} adsorption–desorption measurements. The results show that the CdS/TiO{sub 2} nanocomposites were composed of anatase TiO{sub 2} and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer–Emmett–Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO{sub 2} (6 h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO{sub 2} nanocomposites. The CdS/TiO{sub 2} (6 h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO{sub 2} nanocomposites, controlled experiments were performed by adding different radical scavengers. - Graphical abstract: CdS/TiO{sub 2} nanocomposites were prepared using CTAB by CBD combined with MAHS method. In addition, with increasing microwave irradiation time, the morphology of CdS/TiO{sub 2} changed from popcorn-like to wedge-like structure. - Highlights: • The CdS/TiO{sub 2} was prepared by CBD combined with MAHS two-step method under CTAB. • The morphologies of as-samples were different with the time of

  2. Microwave-assisted silica coating and photocatalytic activities of ZnO nanoparticles

    Siddiquey, Iqbal Ahmed; Furusawa, Takeshi; Sato, Masahide; Suzuki, Noboru

    2008-01-01

    A new and rapid method for silica coating of ZnO nanoparticles by the simple microwave irradiation technique is reported. Silica-coated ZnO nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. The FT-IR spectra and XPS clearly confirmed the silica coating on ZnO nanoparticles. The results of XPS analysis showed that the elements in the coating at the surface of the ZnO nanoparticles were Zn, O and Si. HR-TEM micrographs revealed a continuous and uniform dense silica coating layer of about 3 nm in thickness on the surface of ZnO nanoparticles. In addition, the silica coating on the ZnO nanoparticles was confirmed by the agreement in the zeta potential of the silica-coated ZnO nanoparticles with that of SiO 2 . The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution showed that silica coating effectively reduced the photocatalytic activity of ZnO nanoparticles. Silica-coated ZnO nanoparticles showed excellent UV shielding ability and visible light transparency

  3. Microwave-assisted synthesis of NiS2 nanostructures for supercapacitors and cocatalytic enhancing photocatalytic H2 production

    Pang, Huan; Wei, Chengzhen; Li, Xuexue; Li, Guochang; Ma, Yahui; Li, Sujuan; Chen, Jing; Zhang, Jiangshan

    2014-01-01

    Uniform NiS2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H2 production. Different morphologies of NiS2 nanostructures show different electrochemical and cocatalytic enhancing H2 production activities. Benefited novel nanostructures, NiS2 nanocube electrodes show a large specific capacitance (695 F g−1 at 1.25 A g−1) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS2 nanospheres show highly cocatalytic enhancing photocatalytic for H2 evolution, in which the photocatalytic H2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H2 production rate of 283 μmol h−1. PMID:24389929

  4. Enhanced degradation of 4-nitrophenol by microwave assisted Fe/EDTA process

    Liu Bo, E-mail: yongboliu@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Li Song, E-mail: ls8214@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Zhao Yongjun, E-mail: zyjun2007@126.com [State Key Laboratory of Pollution Control and Resource Reuse, School of Life Science, Nanjing University, Nanjing 210093 (China); Wu Wenfei, E-mail: feibanana6@163.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Zhang Xuxiang, E-mail: zhangxx@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of Life Science, Nanjing University, Nanjing 210093 (China); Gu Xueyuan, E-mail: xygu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Li Ruihua, E-mail: liruihua@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Yang Shaogui, E-mail: ysg420@sina.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China)

    2010-04-15

    A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD{sub 5}/COD{sub Cr} of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods.

  5. Enhanced degradation of 4-nitrophenol by microwave assisted Fe/EDTA process

    Liu Bo; Li Song; Zhao Yongjun; Wu Wenfei; Zhang Xuxiang; Gu Xueyuan; Li Ruihua; Yang Shaogui

    2010-01-01

    A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD 5 /COD Cr of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods.

  6. UV and visible activation of Cr(III)-doped TiO2 catalyst prepared by a microwave-assisted sol-gel method during MCPA degradation.

    Mendiola-Alvarez, S Y; Guzmán-Mar, J L; Turnes-Palomino, G; Maya-Alejandro, F; Hernández-Ramírez, A; Hinojosa-Reyes, L

    2017-05-01

    Photocatalytic degradation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution using Cr(III)-doped TiO 2 under UV and visible light was investigated. The semiconductor material was synthesized by a microwave-assisted sol-gel method with Cr(III) doping contents of 0.02, 0.04, and 0.06 wt%. The catalyst was characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption, UV-Vis diffuse reflectance spectroscopy (DRS), and atomic absorption spectroscopy (AAS). The photocatalytic activity for the photodegradation of MCPA was followed by reversed-phase high-performance liquid chromatography (HPLC) and total organic carbon (TOC) analysis. The intermediates formed during degradation were identified using gas chromatography-mass spectrometry (GC-MS). Chloride ion evolution was measured by ion chromatography. Characterization results showed that Cr(III)-doped TiO 2 materials possessed a small crystalline size, high surface area, and mesoporous structure. UV-Vis DRS showed enhanced absorption in the visible region as a function of the Cr(III) concentration. The Cr(III)-doped TiO 2 catalyst with 0.04 wt% of Cr(III) was more active than bare TiO 2 for the degradation of MCPA under both UV and visible light. The intermediates identified during MCPA degradation were 4-chloro-2-methylphenol (CMP), 2-(4-hydroxy-2-methylphenoxy) acetic acid (HMPA), and 2-hydroxybuta-1,3-diene-1,4-diyl-bis (oxy)dimethanol (HBDM); the formation of these intermediates depended on the radiation source.

  7. Microwave-assisted synthesis of Zn{sub x}Cd{sub 1-x}S-MWCNT heterostructures and their photocatalytic properties

    Wu Huaqiang, E-mail: wuhuaq@mail.ahnu.edu.cn; Yao Youzhi; Li Wenting; Zhu Lulu; Ni Na; Zhang Xiaojun [Anhui Normal University, Anhui Key Laboratory of Molecule-based Materials, College of Chemistry and Materials Science (China)

    2011-05-15

    The multi-walled carbon nanotubes (MWCNTs) wrapped with hexagonal wurtzite Zn{sub x}Cd{sub 1-x}S nanoparticles with a uniform and small diameter have been prepared to form Zn{sub x}Cd{sub 1-x}S-MWCNT heterostructures by microwave-assisted route using Zn(Ac){sub 2}, Cd(NO{sub 3}){sub 2}, and thioacetamide as the reactants{sub .} The heterostructures have been characterized by X-ray powder diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, photoluminescence (PL) and PL excited lifetime. Despite the analogous size and configuration, the Zn{sub x}Cd{sub 1-x}S-MWCNT (x = 0, 0.2, 0.5, 0.8, 1) with different Zn concentration exhibit composition-dependent absorption properties in the visible zone. The PL peak positions of Zn{sub x}Cd{sub 1-x}S-MWCNT change gradually from ZnS-MWCNT to CdS-MWCNT. The Zn{sub x}Cd{sub 1-x}S-MWCNT shows different photocatalytic activity towards the photodegradation of fuchsin acid under visible light illumination, photocatalytic activity of the Zn{sub x}Cd{sub 1-x}S-MWCNT decreases gradually with the increase in the Zn concentration, the Zn{sub 0.2}Cd{sub 0.8}S-MWCNT possessed the best photocatalytic activity. After recycling thrice, the photocatalysts still have about 85% efficiency.

  8. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  9. The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

    Prakoso, S. P.; Paramarta, V.; Tju, H.; Taufik, A.; Saleh, R.

    2016-11-01

    This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag2O), namely Ag2O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag2O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag2O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag2O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag2O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag2O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag2O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag2O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail.

  10. The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

    Prakoso, S. P.; Paramarta, V.; Tju, H.; Taufik, A.; Saleh, R.

    2016-01-01

    This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag 2 O), namely Ag 2 O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag 2 O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag 2 O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag 2 O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag 2 O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag 2 O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag 2 O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag 2 O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail. (paper)

  11. Annealing-free synthesis of C-N co-doped TiO{sub 2} hierarchical spheres by using amine agents via microwave-assisted solvothermal method and their photocatalytic activities

    Wu, Yu-Chun, E-mail: yuchunwu@mail.ncku.edu.tw; Ju, Lung-Shen

    2014-08-01

    Highlights: • The synthesis method for C-N co-doped TiO{sub 2} hierarchical spheres is proposed. • Microwave-assisted solvothermal method is applied. • C and N are doped into TiO{sub 2} via a direct chelating reaction of amine compounds. • The photodegradation rate is eightfold higher than the commercial P25 powders. - Abstract: The annealing-free synthesis of C-N co-doped TiO{sub 2} hierarchical spheres is proposed in this study. C and N were doped into the TiO{sub 2} structure via a direct chelating process to the Ti-precursor by using different amine agents, including hexadecylamine (HDA), diethylamine (DEA), trimethylamine (TMA), and diethylenetriamine (DETA). C-N co-doped TiO{sub 2} spheres (300 nm to 500 nm) composed of nanoparticles approximately 11 nm to 13 nm in size were obtained via an efficient microwave-assisted solvothermal reaction at 190 °C for 60 min. The effects of C and N doping by using different amine compounds on the bandgap energy and photocatalytic performance of TiO{sub 2} were investigated. Among the amine compounds, DETA provided the highest chelating efficiency because it provides two primary amine groups, which resulted in the highest C and N doping concentrations and the largest degree of bandgap narrowing (2.77 eV); nevertheless, the high chelating ratio of C and N restrained the crystallization of TiO{sub 2} and considerably decreased its photocatalytic activity. The use of TMA produced optimal C and N doping concentrations, which effectively reduced the bandgap of TiO{sub 2} to 2.85 eV without affecting its crystallization. Its photodecomposition activity to rhodamine B was eightfold of that of commercial Degussa P25 powders under visible light irradiation.

  12. Microwave-assisted Chemical Transformations

    In recent years, there has been a considerable interest in developing sustainable chemistries utilizing green chemistry principles. Since the first published report in 1986 by Gedye and Giguere on microwave assisted synthesis in household microwave ovens, the use of microwaves as...

  13. NOx photocatalytic degradation employing concrete pavement containing titanium dioxide

    Ballari, M.M.; Hunger, Martin; Hüsken, Götz; Brouwers, Jos

    2010-01-01

    In the present work the degradation of nitrogen oxides (NOx) by concrete paving stones containing TiO2 to be applied in road construction is studied. A kinetic model is proposed to describe the photocatalytic reaction of NOx (combining the degradation of NO and the appearance and disappearance of

  14. Phosphorous-doped TiO2 nanoparticles: synthesis, characterization, and visible photocatalytic evaluation on sulfamethazine degradation.

    Mendiola-Alvarez, Sandra Yadira; Hernández-Ramírez, Ma Aracely; Guzmán-Mar, Jorge Luis; Garza-Tovar, Lorena Leticia; Hinojosa-Reyes, Laura

    2018-05-24

    Mesoporous phosphorous-doped TiO 2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol-gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV-Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO 2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O-H bond were observed by FTIR analysis compared with bare TiO 2 . The P was substitutionally incorporated in the TiO 2 lattice network as P 5+ replacing Ti 4+ to form Ti-O-P bonds and additionally present as PO 4 3-  on the TiO 2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO 2 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.

  15. Microwave assisted chemical vapor infiltration

    Devlin, D.J.; Currier, R.P.; Barbero, R.S.; Espinoza, B.F.; Elliott, N.

    1991-01-01

    A microwave assisted process for production of continuous fiber reinforced ceramic matrix composites is described. A simple apparatus combining a chemical vapor infiltration reactor with a conventional 700 W multimode oven is described. Microwave induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the ''inside out'' deposition of SiC via decomposition of methyltrichlorosilane in hydrogen are presented. Several key processing issues are identified and discussed. 5 refs

  16. Visible light induced photocatalytic degradation of some xanthene ...

    Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor immobilized on polyethylene films. Effect of various parameters like pH, concentration of dyes, amount of semiconductor and light intensity have been studied on the rate of reaction. Various control ...

  17. Photocatalytic Degradation of Aniline Using TiO2 Nanoparticles in a Vertical Circulating Photocatalytic Reactor

    F. Shahrezaei

    2012-01-01

    Full Text Available Photocatalytic degradation of aniline in the presence of titanium dioxide (TiO2 and ultraviolet (UV illumination was performed in a vertical circulating photocatalytic reactor. The effects of catalyst concentration (0–80 mg/L, initial pH (2–12, temperature (293–323 K, and irradiation time (0–120 min on aniline photodegradation were investigated in order to obtain the optimum operational conditions. The results reveal that the aniline degradation efficiency can be effectively improved by increasing pH from 2 to 12 and temperature from 313 to 323 K. Besides, the effect of temperature on aniline photo degradation was found to be unremarkable in the range of 293–313 K. The optimum catalyst concentration was about 60 mg/L. The Langmuir Hinshelwood kinetic model could successfully elucidate the effects of the catalyst concentration, pH, and temperature on the rate of heterogeneous photooxidation of aniline. The data obtained by applying the Langmuir Hinshelwood treatment are consistent with the available kinetic parameters. The activated energy for the photocatalytic degradation of aniline is 20.337 kj/mol. The possibility of the reactor use in the treatment of a real petroleum refinery wastewater was also investigated. The results of the experiments indicated that it can therefore be potentially applied for the treatment of wastewater contaminated by different organic pollutants.

  18. Photocatalytic degradation of rosuvastatin: Analytical studies and toxicity evaluations

    Machado, Tiele Caprioli, E-mail: tiele@enq.ufrgs.br [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil); Pizzolato, Tânia Mara [Chemical Institute, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Arenzon, Alexandre [Ecology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Segalin, Jeferson [Biotechnology Center, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, CEP: 91501-970 Porto Alegre, RS (Brazil); Lansarin, Marla Azário [Chemical Engineering Department, Federal University of Rio Grande do Sul, Rua Engenheiro Luiz Englert s/n, CEP: 90040-040 Porto Alegre, RS (Brazil)

    2015-01-01

    Photocatalytic degradation of rosuvastatin, which is a drug that has been used to reduce blood cholesterol levels, was studied in this work employing ZnO as catalyst. The experiments were carried out in a temperature-controlled batch reactor that was irradiated with UV light. Preliminary the effects of the photocatalyst loading, the initial pH and the initial rosuvastatin concentration were evaluated. The experimental results showed that rosuvastatin degradation is primarily a photocatalytic process, with pseudo-first order kinetics. The byproducts that were generated during the oxidative process were identified using nano-ultra performance liquid chromatography tandem mass spectrometry (nano-UPLC–MS/MS) and acute toxicity tests using Daphnia magna were done to evaluate the toxicity of the untreated rosuvastatin solution and the reactor effluent. - Highlights: • The photocatalytic degradation of rosuvastatin was studied under UV irradiation. • Commercial catalyst ZnO was used. • Initial rosuvastatin concentration, photocatalyst loading and pH were evaluated. • The byproducts generated during the oxidative process were detected and identified. • Acute toxicity tests using Daphnia magna were carried out.

  19. Photocatalytic degradation of methyl red dye by silica nanoparticles

    Badr, Y. [National Institute of Laser Enhanced Science, Cairo University, Cairo (Egypt); Abd El-Wahed, M.G. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig (Egypt); Mahmoud, M.A. [Chemistry Department, Faculty of Science, Zagazig University, Zagazig (Egypt)], E-mail: mahmoudchem@yahoo.com

    2008-06-15

    Silica nanoparticles (SiO{sub 2} NPs) were found to be photocatalytically active for degradation of methyl red dye (MR). The SiO{sub 2} NPs and SiO{sub 2} NPs doped with silver (and or) gold nanoparticles were prepared. From the transmission electron microscopy (TEM) images the particle size and particle morphology of catalysts were monitored. Moreover, SiO{sub 2} NPs doped with silver and gold ions were used as a photocatalyst for degradation of MR. The rate of photocatalytic degradation of MR was found to be increased in the order of SiO{sub 2} NPs, SiO{sub 2} NPs coated with gold nanoparticles (Au NPs) and silver nanoparticles (Ag NPs), SiO{sub 2} NPs coated with Ag NPs, SiO{sub 2} NPs coated with Au NPs, Ag{sup +}-doped SiO{sub 2} NPs, and Au{sup 3+}-doped SiO{sub 2} NPs. The kinetic and mechanism of photocatalytic reaction were studied and accorded well with experimental results.

  20. PHOTOCATALYTIC DEGRADATION OF CRYSTAL VIOLET BY ...

    In recent years, removal of undesirable organic contaminants from water and wastewater is ... accidental leakage of tanks containing pollutants, etc. ..... Consideration of reaction pathways and degradation rates is critical for detection of waste.

  1. TiO₂-Based Photocatalytic Geopolymers for Nitric Oxide Degradation.

    Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

    2016-06-24

    This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO₂ by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

  2. Synthesis of N and La co-doped TiO{sub 2}/AC photocatalyst by microwave irradiation for the photocatalytic degradation of naphthalene

    Liu, Dandan; Wu, Zhansheng, E-mail: wuzhans@126.com; Tian, Fei; Ye, Bang-Ce; Tong, Yanbin, E-mail: tongyanbin@sina.com

    2016-08-15

    La and N co-doped TiO{sub 2} nanoparticles supported on activated carbon (TiO{sub 2}/AC) were synthesized through a microwave-assisted sol–gel method for the synergistic removal of naphthalene solution by photocatalytic degradation. Results showed that the La and N ions were incorporated into the TiO{sub 2} framework in both the anatase and rutile phases of TiO{sub 2} for single doped and co-doped samples, which narrowed the band gap of TiO{sub 2} from 2.82 to 2.20 eV. The PL spectra of the samples showed a decrease in the recombination centers when N and La were introduced in TiO{sub 2}/AC. The 0.001La-N-TiO{sub 2}/AC photocatalyst exhibited the highest degradation efficiency of 93.5% for naphthalene under visible light within 120 min. This result was attributed to a synergistic effect involving the efficient inhibition of the recombination of photogenerated electrons and holes, the increase in surface hydroxyl, surface area, volume pores, and the increase of uptake in the visible light region. In addition, the high apparent rate constant indicated that La and N co-doping result in the increase of photoactivity. This study demonstrated the co-doped TiO{sub 2}/AC is a highly efficient photocatalyst for the removal of naphthalene. The results provided valuable information on the mechanism of naphthalene decomposition. - Highlights: • N, La codoped TiO{sub 2}/AC catalysts were synthesized by microwave-assisted. • N and La doping inhibit the recombination of photogenerated electrons and holes. • 0.001La-N-TiO{sub 2}/AC obtains photodegradation efficiency of 93.5% for naphthalene. • The photocatalysts possess good photochemical stability and reusability.

  3. Improved photocatalytic degradation of Orange G using hybrid nanofibers

    Ledwaba, Mpho; Masilela, Nkosiphile; Nyokong, Tebello; Antunes, Edith, E-mail: ebeukes@uwc.ac.za [Rhodes University, Department of Chemistry (South Africa)

    2017-05-15

    Functionalised electrospun polyamide-6 (PA-6) nanofibres incorporating gadolinium oxide nanoparticles conjugated to zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) as the sensitizer were prepared for the photocatalytic degradation of Orange G. Fibres incorporating the phthalocyanine alone or a mixture of the nanoparticles and phthalocyanine were also generated. The singlet oxygen-generating ability of the sensitizer was shown to be maintained within the fibre mat, with the singlet oxygen quantum yields increasing upon incorporation of the magnetic nanoparticles. Consequently, the rate of the photodegradation of Orange G was observed to increase with an increase in singlet oxygen quantum yield. A reduction in the half-lives for the functionalised nanofibres was recorded in the presence of the magnetic nanoparticles, indicating an improvement in the efficiency of the degradation process.

  4. Ceramic matrix composites by microwave assisted CVI

    Currier, R.P.; Devlin, D.J.

    1993-01-01

    Chemical vapor infiltration (CVI) processes for producing continuously reinforced ceramic composites are reviewed. Potential advantages of microwave assisted CVI are noted and numerical studies of microwave assisted CVI are reviewed. The models predict inverted thermal gradients in fibrous ceramic preforms subjected to microwave radiation and suggest processing strategies for achieving uniformly dense composites. Comparisons are made to experimental results on silicon-based composite systems. The role played by the relative ability of fiber and matrix to dissipate microwave energy is noted. Results suggest that microwave induced inverted gradients can be exploited to promote inside-out densification. 10 refs., 2 figs

  5. Microwave-assisted synthesis of bismuth oxybromochloride nanoflakes for visible light photodegradation of pollutants

    Bijanzad, Keyvan; Tadjarodi, Azadeh; Moghaddasi Khiavi, Mohammad [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.ir [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of)

    2015-10-15

    BiOBr{sub x}Cl{sub 1−x} (0microwave-assisted synthesis method. The X-ray diffraction (XRD) studies confirmed the formation of pure crystalline phase of BiOBr{sub x}Cl{sub 1−x}. The UV–visible diffuse reflectance and photoluminescence (PL) spectroscopies revealed the indirect band gap of ~2.82 eV for the bismuth oxybromochloride nanoflakes. Visible light-assisted photocatalytic studies showed that the degradation efficiency of the as-prepared BiOBr{sub x}Cl{sub 1−x} for (100 mL of 10 mg L{sup −1}) Rhodamine B (RhB), Natural Red 4 (N-Red) dye solutions was 98.14% and for the colorless organic pentachlorophenol (PCP) solution was 91.09% over 150 min. The possible mechanisms involved in the visible light photodegradation of the pollutants by BiOBr{sub x}Cl{sub 1−x} photocatalyst were also discussed.

  6. Flexible composite via rapid titania coating by microwave-assisted ...

    2017-06-09

    Jun 9, 2017 ... carbon fibre via microwave-assisted hydrothermal synthesis (MHS) ... Nanoparticles; titanium dioxide; microwave-assisted hydrothermal synthesis; carbon fibre. ..... study, the carbon fibre absorbs microwave radiation and con-.

  7. Microwave-assisted organic and polymer chemistry

    Hoogenboom, R.; Schubert, U.S.

    2009-01-01

    The first ACS symposium on Microwave-Assisted Chemistry: Organic and Polymer Synthesis, held as part of the ACS National meeting in Philadelphia, in August 2008, aimed at various topics of the use of microwave irradiation. The symposium found that specific heating effects, such as higher microwave

  8. Photocatalytic degradation of tartrazine dye using CuO straw-sheaf-like nanostructures.

    Rao, Martha Purnachander; Wu, Jerry J; Asiri, Abdullah M; Anandan, Sambandam

    2017-03-01

    Straw-sheaf-like CuO nanostructures were fruitfully synthesized using a chemical precipitation approach for the photocatalytic degradation assessment of tartrazine. Phase identification, composition, and morphological outlook of prepared CuO nanostructures were established by X-ray diffraction and scanning electron microscopy analysis. The photocatalytic performance of the synthesized CuO nanostructures was appraised in the presence of visible light and the possible intermediates formed during the photocatalytic degradation were analyzed by gas chromatography-mass spectrometry. A suitable degradation pathway has also been proposed.

  9. Solar photocatalytic degradation and detoxification of EU priority substances

    Hincapie, M. [Facultad de Ingeniera Ambiental, Universidad de Medellin, Carrera 87 No. 30-65, P.O. Box 1983, Medellin (Colombia); Maldonado, M.I.; Oller, I.; Gernjak, W.; Malato, S. [Plataforma Solar de Almeria-CIEMAT, Carretera Senes km4, 04200 Tabernas (Almeria) (Spain); Sanchez-Perez, J.A.; Ballesteros, M.M. [Departamento de Ingenieria Quimica, Universidad de Almeria Crta de Sacramento s/n, 04120 Almeria (Spain)

    2005-04-15

    Several different pesticides (alachlor, atrazine, chlorfenvinphos, diuron, isoproturon and pentachlorophenol) considered PS (priority substances) by the European Commission and dissolved in water at 50mg/L (or at maximum water solubility) have been degraded at pilot-plant scale using photo-Fenton and TiO{sub 2} photocatalysis driven by solar energy. Two different iron concentrations (2 and 55mg/L) and TiO{sub 2} at 200mg/L have been tested and discussed, using mainly TOC mineralisation for comparison of treatment effectiveness. Vibrio fischeri (Microtox{sup (}R)) toxicity assays were also employed for evaluating the photocatalytic treatments, and comparison between these results and parent compound disappearance, TOC evolution and anion (or ammonia) release were discussed. Almost complete mineralisation and total detoxification were always attained. It has been demonstrated that evolution of chloride could be a key-parameter for predicting toxicity of chlorinated compounds.

  10. Photocatalytic degradation of methylene blue by C 3 N 4 /ZnO

    The photocatalytic activities of prepared samples were investigated under the illumination of blacklight and fluorescent lamps as the low wattage light source. The C 3 N 4 /ZnO showed a better photocatalytic activity than ZnO to degrade a methylene blue (MB) dye solution using blacklight lamps, but there is no significant ...

  11. Determination of X-Ray Diffraction on the Phase Transformation of Microwave-Assisted Titanate Nanotubes during Thermal Treatment

    Hsin-Hung Ou

    2010-01-01

    Full Text Available Based on the determination of X-ray powder diffraction, this study aims to investigate the thermal effect on the phase transformation of microwave-assisted titanate nanotubes (MTNTs. The phase transformation is highly dependent on the intercalating amount of Na(I within MTNTs and on the heating atmosphere. In other words, the presence of Na(I favors the transformation of TNTs phase into Na2Ti6O13 whereas anatase phase selectively formed in the case of MTNTs with less Na(I amount. Furthermore, H2 versus O2 is able to form anatase phase and establish a newly transformation pathway. The photocatalytic ability of the calcined MTNTs was also evaluated based on the observed rate constant of trichloroethylene degradation. In addition to anatase phase, the newly phase including Na2Ti6O13 and Ti2O3 with calcined MTNTs is able to photocatalyze trichloroethylene. MTNTs calcined with the presence of H2 also exhibit a superior photocatalytic performance to P25 TiO2.

  12. Photocatalytic degradation using design of experiments: a review and example of the Congo red degradation.

    Sakkas, Vasilios A; Islam, Md Azharul; Stalikas, Constantine; Albanis, Triantafyllos A

    2010-03-15

    The use of chemometric methods such as response surface methodology (RSM) based on statistical design of experiments (DOEs) is becoming increasingly widespread in several sciences such as analytical chemistry, engineering and environmental chemistry. Applied catalysis, is certainly not the exception. It is clear that photocatalytic processes mated with chemometric experimental design play a crucial role in the ability of reaching the optimum of the catalytic reactions. The present article reviews the major applications of RSM in modern experimental design combined with photocatalytic degradation processes. Moreover, the theoretical principles and designs that enable to obtain a polynomial regression equation, which expresses the influence of process parameters on the response are thoroughly discussed. An original experimental work, the photocatalytic degradation of the dye Congo red (CR) using TiO(2) suspensions and H(2)O(2), in natural surface water (river water) is comprehensively described as a case study, in order to provide sufficient guidelines to deal with this subject, in a rational and integrated way. (c) 2009 Elsevier B.V. All rights reserved.

  13. Heterogeneous photocatalytic degradation of p-toluenesulfonic acid using concentrated solar radiation in slurry photoreactor

    Kamble, Sanjay P.; Sawant, Sudhir B.; Pangarkar, Vishwas G.

    2007-01-01

    In this work, the photocatalytic degradation (PCD) of p-toluenesulfonic acid (p-TSA) in batch reactor using concentrated solar radiation was investigated. The effect of the various operating parameters such as initial concentration of substrate, catalyst loading, solution pH and types of ions on photocatalytic degradation has been studied in a batch reactor to derive the optimum conditions. The rate of photocatalytic degradation was found to be maximum at the self pH (pH 3.34) of p-TSA. It was also observed that in the presence of anions and cations, the rate of PCD decreases drastically. The kinetics of photocatalytic degradation of p-TSA was studied. The PCD of p-TSA was also carried at these optimized conditions in a bench scale slurry bubble column reactor using concentrated solar radiation

  14. Photocatalytic degradation of diethyl phthalate using TiO{sub 2} nanoparticles

    Singla, Pooja, E-mail: pooja.singla@thapar.edu; Pandey, O. P., E-mail: pooja.singla@thapar.edu; Singh, K., E-mail: pooja.singla@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

    2014-04-24

    TiO{sub 2} nanoparticles predominantly in rutile phase are synthesized by ultrasonication assisted sol-gel method. TiO{sub 2} powder is characterized using X-ray powder diffraction and UV-vis diffuse reflectance. TiO{sub 2} is used as catalyst in photocatalytic degradation of Diethyl Phthalate. TiO{sub 2} exhibits good photocatalytic activity for the degradation of diethyl phthalate.

  15. Enhanced visible-light-responsive photodegradation of bisphenol A by Cu, N-codoped titanate nanotubes prepared by microwave-assisted hydrothermal method

    Doong, Ruey-an, E-mail: radoong@nctu.edu.tw [Institute of Environmental Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liao, Chun-Yi [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2017-01-15

    Highlights: • The Cu, N-codoped TNTs were prepared by microwave assisted hydrothermal method. • The Cu(0) in codoped TNTs can serve as electron donors as well as electron meditors. • The surface normalized rate constants for BPA removal by Cu, N-TNT were 1.5–4.3 times higher than that of P25 TiO{sub 2}. • The Cu, N-codoped TNTs prolonged the generation of radicals for at least 5 min. - Abstract: In this study, a rapid and effective microwave-assisted hydrothermal method was developed for the synthesis of Cu, N-codoped titanate nanotubes (Cu, N-TNTs) to enhance the photocatalytic degradation efficiency and rate of bisphenol A (BPA) under UV and visible light irradiations. The TNTs were first synthesized at 150 °C for 3 h under microwave heating conditions followed by the calcination at 450 °C in the presence of 6 wt% Cu ions and N{sub 2}/NH{sub 3} to fabricate Cu, N-TNTs composites. The Cu, N-TNTs exhibited excellent photocatalytic activity toward BPA degradation under UV and visible light irradiations. The X-ray photoelectron spectra indicated that Cu species in Cu, N-TNTs were mainly in zerovalent form and could serve as the electron donors as well as shuttling species to accelerate the photodegradation of BPA. In addition, the nitrogen atoms were incorporated into the anatase lattices to increase the visible-light-responsive capability. The surface normalized reaction rate constants for BPA degradation were 4.3 and 1.5 times higher than those of Degussa P25 TiO{sub 2} under UV and visible light irradiations, respectively. The electron spin resonance spectra showed that Cu, N-codoped TNTs prolonged the generation of oxygen-containing radicals for at least 5 min, resulting in the significant enhancement of photodegradation efficiency and rate of BPA. Results obtained in this study open a new avenue by using simple and effective microwave-assisted hydrothermal method to fabricate low dimensional codoped TNTs which can be potentially applied in a wide

  16. Enhanced visible-light-responsive photodegradation of bisphenol A by Cu, N-codoped titanate nanotubes prepared by microwave-assisted hydrothermal method

    Doong, Ruey-an; Liao, Chun-Yi

    2017-01-01

    Highlights: • The Cu, N-codoped TNTs were prepared by microwave assisted hydrothermal method. • The Cu(0) in codoped TNTs can serve as electron donors as well as electron meditors. • The surface normalized rate constants for BPA removal by Cu, N-TNT were 1.5–4.3 times higher than that of P25 TiO_2. • The Cu, N-codoped TNTs prolonged the generation of radicals for at least 5 min. - Abstract: In this study, a rapid and effective microwave-assisted hydrothermal method was developed for the synthesis of Cu, N-codoped titanate nanotubes (Cu, N-TNTs) to enhance the photocatalytic degradation efficiency and rate of bisphenol A (BPA) under UV and visible light irradiations. The TNTs were first synthesized at 150 °C for 3 h under microwave heating conditions followed by the calcination at 450 °C in the presence of 6 wt% Cu ions and N_2/NH_3 to fabricate Cu, N-TNTs composites. The Cu, N-TNTs exhibited excellent photocatalytic activity toward BPA degradation under UV and visible light irradiations. The X-ray photoelectron spectra indicated that Cu species in Cu, N-TNTs were mainly in zerovalent form and could serve as the electron donors as well as shuttling species to accelerate the photodegradation of BPA. In addition, the nitrogen atoms were incorporated into the anatase lattices to increase the visible-light-responsive capability. The surface normalized reaction rate constants for BPA degradation were 4.3 and 1.5 times higher than those of Degussa P25 TiO_2 under UV and visible light irradiations, respectively. The electron spin resonance spectra showed that Cu, N-codoped TNTs prolonged the generation of oxygen-containing radicals for at least 5 min, resulting in the significant enhancement of photodegradation efficiency and rate of BPA. Results obtained in this study open a new avenue by using simple and effective microwave-assisted hydrothermal method to fabricate low dimensional codoped TNTs which can be potentially applied in a wide variety of fields of

  17. Photocatalytic Degradation of 4-Nitrophenol by C, N-TiO2: Degradation Efficiency vs. Embryonic Toxicity of the Resulting Compounds

    Osin, Oluwatomiwa A.; Yu, Tianyu; Cai, Xiaoming; Jiang, Yue; Peng, Guotao; Cheng, Xiaomei; Li, Ruibin; Qin, Yao; Lin, Sijie

    2018-06-01

    The photocatalytic activity of TiO2 based photocatalysts can be improved by structural modification and elemental doping. In this study, through rational design, one type of carbon and nitrogen co-doped TiO2 (C, N-TiO2) photocatalyst with mesoporous structure was synthesized with improved photocatalytic activity in degrading 4-nitrophenol under simulated sunlight irradiation. The photocatalytic degradation efficiency of the C, N-TiO2 was much higher than the anatase TiO2 (A-TiO2) based on absorbance and HPLC analyses. Moreover, using zebrafish embryos, we showed that the intermediate degradation compounds generated by photocatalytic degradation of 4-nitrophenol had higher toxicity than the parent compound. A repeated degradation process was necessary to render complete degradation and non-toxicity to the zebrafish embryos. Our results demonstrated the importance of evaluating the photocatalytic degradation efficiency in conjunction with the toxicity assessment of the degradation compounds.

  18. Assessment of Microwave/UV/O3 in the Photo-Catalytic Degradation of Bromothymol Blue in Aqueous Nano TiO2 Particles Dispersions

    Kim Sun-Jae

    2010-01-01

    Full Text Available Abstract In this study, a microwave/UV/TiO2/ozone/H2O2 hybrid process system, in which various techniques that have been used for water treatment are combined, is evaluated to develop an advanced technology to treat non-biodegradable water pollutants efficiently. In particular, the objective of this study is to develop a novel advanced oxidation process that overcomes the limitations of existing single-process water treatment methods by adding microwave irradiation to maximize the formation of active intermediate products, e.g., OH radicals, with the aid of UV irradiation by microwave discharge electrodeless lamp, photo-catalysts, and auxiliary oxidants. The results of photo-catalytic degradation of BTB showed that the decomposition rate increased with the TiO2 particle dosages and microwave intensity. When an auxiliary oxidant such as ozone or hydrogen peroxide was added to the microwave-assisted photo-catalysis, however, a synergy effect that enhanced the reaction rate considerably was observed.

  19. Degradation of ethylenethiourea pesticide metabolite from water by photocatalytic processes.

    Bottrel, Sue Ellen C; Amorim, Camila C; Leão, Mônica M D; Costa, Elizângela P; Lacerda, Igor A

    2014-01-01

    In this study, photocatalytic (photo-Fenton and H2O2/UV) and dark Fenton processes were used to remove ethylenethiourea (ETU) from water. The experiments were conducted in a photo-reactor with an 80 W mercury vapor lamp. The mineralization of ETU was determined by total organic carbon analysis, and ETU degradation was qualitatively monitored by the reduction of UV absorbance at 232 nm. A higher mineralization efficiency was obtained by using the photo-peroxidation process (UV/H2O2). Approximately 77% of ETU was mineralized within 120 min of the reaction using [H2O2]0 = 400 mg L(-1). The photo-Fenton process mineralized 70% of the ETU with [H2O2]0 = 800 mg L(-1) and [Fe(2+)] = 400 mg L(-1), and there is evidence that hydrogen peroxide was the limiting reagent in the reaction because it was rapidly consumed. Moreover, increasing the concentration of H2O2 from 800 mg L(-1) to 1200 mg L(-1) did not enhance the degradation of ETU. Kinetics studies revealed that the pseudo-second-order model best fit the experimental conditions. The k values for the UV/H2O2 and photo-Fenton processes were determined to be 6.2 × 10(-4) mg L(-1) min(-1) and 7.7 × 10(-4) mg L(-1) min(-1), respectively. The mineralization of ETU in the absence of hydrogen peroxide has led to the conclusion that ETU transformation products are susceptible to photolysis by UV light. These are promising results for further research. The processes that were investigated can be used to remove pesticide metabolites from drinking water sources and wastewater in developing countries.

  20. Application of zinc oxide fiber in the photocatalytic degradation of methyl orange

    Gerchman, D.; Alves, A.K.; Berutti, F.A.; Bergmann, C.P.

    2011-01-01

    In this work, zinc oxide fibers were obtained by electrospinning using polyvinylbutyral and zinc nitrate as precursors. After the synthesis, the material was heat treated at different temperatures to evaluate the effect of microstructure on its photocatalytic activity. The fibers obtained after heat treatment were characterized for morphology, phases, crystallinity and photocatalytic activity. The photocatalysis reaction was accompanied by the degradation of methyl orange in the presence of zinc oxide under UV illumination. It was observed that the crystallinity of zincite is a fundamental factor for the control of the photocatalytic activity of this material. (author)

  1. Influence of Ti–O–Si hetero-linkages in the photocatalytic degradation of Rhodamine B

    Rasalingam, S; Kibombo, H.S.; Wu, C.M.; Budhi, S.; Peng, R.; Baltrusaitis, Jonas; Koodali, R.T.

    2013-01-01

    The influence of Ti–O–Si hetero-linkages in the degradation of Rhodamine B (RhB) dye over TiO2–SiO2 xerogels is exemplified by XPS analysis. We demonstrate a relationship between the percentage surface content of Ti–O–Si and the rate of photocatalytic degradation of RhB. Our detailed surface

  2. Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

    Prasad, G.K.; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

    2012-01-01

    Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 × 10 −3 min −1 . Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 × 10 −3 min −1 due to photocatalysis. Gas chromatography–mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P–O–C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: ► Synthesis of titania nanoparticles by sol–gel method. ► Fabrication of titania nanoparticulate film by dip coating. ► Paraoxon ethyl degradation reactions followed pseudo first order behaviour. ► Paraoxon-ethyl degraded to non toxic compounds like CO 2 , acetaldehyde, and nitrophenol.

  3. Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

    Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

    2012-06-30

    Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 Multiplication-Sign 10{sup -3} min{sup -1}. Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 Multiplication-Sign 10{sup -3} min{sup -1} due to photocatalysis. Gas chromatography-mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P-O-C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: Black-Right-Pointing-Pointer Synthesis of titania nanoparticles by sol-gel method. Black-Right-Pointing-Pointer Fabrication of titania nanoparticulate film by dip coating. Black-Right-Pointing-Pointer Paraoxon ethyl degradation reactions followed pseudo first order behaviour. Black-Right-Pointing-Pointer Paraoxon-ethyl degraded to non toxic compounds like CO{sub 2}, acetaldehyde, and nitrophenol.

  4. Photocatalytic degradation of diuron in aqueous solution by platinized TiO2

    Katsumata, Hideyuki; Sada, Maki; Nakaoka, Yusuke; Kaneco, Satoshi; Suzuki, Tohru; Ohta, Kiyohisa

    2009-01-01

    The photocatalytic degradation of diuron, which is one of phenylurea herbicides, was carried out in the presence of platinized TiO 2 photocatalyst. Platinization was found to increase the rate of diuron degradation. When 0.2 wt.% of platinum was deposited onto the surface of TiO 2 , an initial diuron concentration of 10 mg L -1 was completely degraded after 20 min. Furthermore, the first-order rate constant for diuron degradation by Pt-TiO 2 was ca. 4 times higher than P-25 TiO 2 . In addition, the photocatalytic activity of Pt-TiO 2 was appeared under visible light. The decrease of TOC as a result of mineralization of diuron was observed during the photocatalytic process. The degree of diuron mineralization was about 97% under UV irradiation after 8 h. The formations of chloride, nitrate and ammonium ions as end-products were observed during the photocatalytic system. The decomposition of diuron gave four kinds of intermediate products. The degradation mechanism of diuron was proposed on the base of the evidence of the identified intermediates. Based on these results, the photocatalytic reaction by Pt-TiO 2 could be useful technology for the treatment of wastewater containing diuron.

  5. Photocatalytic degradation of diuron in aqueous solution by platinized TiO{sub 2}

    Katsumata, Hideyuki, E-mail: hidek@chem.mie-u.ac.jp [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Sada, Maki; Nakaoka, Yusuke; Kaneco, Satoshi [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Suzuki, Tohru [Environmental Preservation Center, Mie University, Tsu, Mie 514-8507 (Japan); Ohta, Kiyohisa [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu, Mie 514-8507 (Japan)

    2009-11-15

    The photocatalytic degradation of diuron, which is one of phenylurea herbicides, was carried out in the presence of platinized TiO{sub 2} photocatalyst. Platinization was found to increase the rate of diuron degradation. When 0.2 wt.% of platinum was deposited onto the surface of TiO{sub 2}, an initial diuron concentration of 10 mg L{sup -1} was completely degraded after 20 min. Furthermore, the first-order rate constant for diuron degradation by Pt-TiO{sub 2} was ca. 4 times higher than P-25 TiO{sub 2}. In addition, the photocatalytic activity of Pt-TiO{sub 2} was appeared under visible light. The decrease of TOC as a result of mineralization of diuron was observed during the photocatalytic process. The degree of diuron mineralization was about 97% under UV irradiation after 8 h. The formations of chloride, nitrate and ammonium ions as end-products were observed during the photocatalytic system. The decomposition of diuron gave four kinds of intermediate products. The degradation mechanism of diuron was proposed on the base of the evidence of the identified intermediates. Based on these results, the photocatalytic reaction by Pt-TiO{sub 2} could be useful technology for the treatment of wastewater containing diuron.

  6. Rapid microwave-assisted nonaqueous synthesis and growth mechanism of AgCl/Ag, and its daylight-driven plasmonic photocatalysis.

    Jiang, Jing; Zhang, Lizhi

    2011-03-21

    We report on a rapid microwave-assisted nonaqueous synthesis and the growth mechanism of AgCl/Ag with controlled size and shape. By rationally varying the reaction temperature and the microwave irradiation time, we achieved the transformation of nanocubes to rounded triangular pyramids by a combined process of "oriented attachment" and Ostwald ripening. The surface plasmon resonance (SPR) properties of the as-prepared AgCl/Ag have been found to be somewhat dependent on the size, morphology, and composition. The as-prepared AgCl/Ag exhibits high photocatalytic activity and good reusability for decomposing organic pollutants (such as methyl orange (MO), rhodamine B (RhB), and pentachlorophenol (PCP)) under indoor artificial daylight illumination (ca. 1 mW cm(-2)). The AgCl/Ag has also been found to display a superior ability to harvest diffuse indoor daylight (ca. 5 mW cm(-2)), and could complete the degradation of 10 mg  L(-1) MO within 15 min. Experiments involving the trapping of active species have shown that the photocatalytic degradation of organic pollutants in the AgCl/Ag system may proceed through direct hole transfer. This study has revealed that plasmonic daylight photocatalysis may open a new frontier for indoor pollutant control around the clock under fluorescent lamp illumination. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation

    Sojic, Daniela V., E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Despotovic, Vesna N., E-mail: vesna.despotovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Abazovic, Nadica D., E-mail: kiki@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Comor, Mirjana I., E-mail: mirjanac@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Abramovic, Biljana F., E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia)

    2010-07-15

    The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ({lambda} {>=} 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO{sub 2} (rutile/anatase) and of the most frequently used TiO{sub 2} Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

  8. Photocatalytic degradation of indigo carmine by ZnO photocatalyst under visible light irradiation

    Ali Al- Taie

    2017-09-01

    Full Text Available In this work, the photocatalytic degradation of indigo carmine (IC using zinc oxide suspension was studied. The effect of influential parameters such as initial indigo carmine concentration and catalyst loading were studied with the effect of Vis irradiation in the presence of reused ZnO was also investigated. The increased in initial dye concentration decreased the photodegradation and the increased catalyst loading increased the degradation percentage and the reused-ZnO exhibits lower photocatalytic activity than the ZnO catalyst. It has been found that the photocatalytic degradation of indigo carmine obeyed the pseudo-first-order kinetic reaction in presence of zinc oxide. This was found from plotting the relationship between ln (C0/Ct and irradiation the rate constant of the process.UV- spectrophotometer was used to study the indigo carmine photodegradation

  9. The effect of operational parameters on the photocatalytic degradation of pesticide.

    Choi, Euiso; Cho, Il-Hyoung; Park, Jaehong

    2004-01-01

    The photocatalytic degradation of Cartap Hydrochloride, a synthetic pesticide. has been investigated over coated TiO2 photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., Cartap Hydrochloride concentration, reaction time, light intensity and additive on the degradation rate of aqueous solution of Cartap Hydrochloride has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Cartap Hydrochloride solutions.

  10. Microwave-assisted grinding of metallurgical coke

    Ruisanchez, E.; Juarez-Perez, E. J.; Arenillas, A.; Bermudez, J. M.; Menendez, J. A.

    2014-01-01

    Metallurgical cokes are composed of graphitic carbon (s2p2) and different inorganic compounds with very different capacities to absorb microwave radiation. Moreover, due to the electric conductivity shown by the metallurgical cokes, microwave radiation produces electric arcs or microplasmas, which gives rise to hot spots. Therefore, when these cokes are irradiated with microwaves some parts of the particle experiment a rapid heating, while some others do not heat at all. As a result of the different expansion and stress caused by thermal the shock, small cracks and micro-fissures are produced in the particle. The weakening of the coke particles, and therefore an improvement of its grind ability, is produced. This paper studies the microwave-assisted grinding of metallurgical coke and evaluates the grinding improvement and energy saving. (Author)

  11. Photocatalytic degradation of methyl orange using ZnO/TiO2 composites

    Ming GE; Changsheng GUO; Xingwang ZHU; Lili MA; Zhefian HAN; Wei HU; Yuqiu WANG

    2009-01-01

    ZnO/TiO2 composites were synthesized by using the solvothermal method and ultrasonic precipitation followed by heat treatment in order to investigate their photocatalytic degradation of methyl orange (MO) in aqueous suspension under UV irradiation. The composi-tion and surface structure of the catalyst were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM). The degradation efficiencies of MO at various pH values were obtained. The highest degradation efficiencies were obtained before 30 min and after 60 min at pH 11.0 and pH 2.0, respectively. A sample analysis was conducted using liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry. Six intermediates were found during the photocatalytic degradation process of quinonoid MO. The degradation pathway of quinonoid MO was also proposed.

  12. An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

    Patole, Shashikant P.

    2015-10-21

    It is common for as-prepared carbon nanotube (CNT) and graphene samples to contain remnants of the transition metals used to catalyze their growth; contamination may also leave other trace elemental impurities in the samples. Although a full quantification of impurities in as-prepared samples of carbon nanostructures is difficult, particularly when trace elements are intercalated or encapsulated within a protective layer of graphitic carbon, reliable information is essential for reasons such as quantifying the adulteration of physico-chemical properties of the materials and for evaluating environmental issues. Here, we introduce a microwave-based fusion method to degrade single- and double-walled CNTs and graphene nanoplatelets into a fusion flux thereby thoroughly leaching all metallic impurities. Subsequent dissolution of the fusion product in diluted hydrochloric and nitric acid allowed us to identify their trace elemental impurities using inductively coupled plasma optical emission spectrometry. Comparisons of the results from the proposed microwave-assisted fusion method against those of a more classical microwave-assisted acid digestion approach suggest complementarity between the two that ultimately could lead to a more reliable and less costly determination of trace elemental impurities in carbon nanostructured materials. Graphical abstract A method for the complete digestion of carbon nanostructures has been demonstrated. Photographs (on the left side) show zirconium crucibles containing SWCNTs with flux of Na2CO3 and K2CO3, before and after microwave fusion; (on the right side) the appearance of the final solutions containing dissolved samples, from microwave-assisted fusion and microwave-assisted acid digestion. These solutions were used for determining the trace elemental impurities by ICP‒OES.

  13. Microwave-assisted Polymerization of D, L-Lactide with Stannous Octanoate as Catalyst

    2001-01-01

    Poly (lactic acid) (PLA) was synthesized by microwave-assisted ring-opening poly- merization of D, L-lactide with stannous octanoate (SnOct2) as catalyst. Its weight-average molar mass (Mw) ranged from 39000 to 67000 and the polydispersity index from 1.3 to 1.7. The polymerization rate was much faster than that of the conventional thermal polymerization. A degradation of newly formed PLA in reaction mixture by microwave irradiation was observed.

  14. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  15. Enhancing Photocatalytic Degradation of Methyl Blue Using PVP-Capped and Uncapped CdSe Nanoparticles

    Kgobudi Frans Chepape

    2017-01-01

    Full Text Available Quantum confinement of semiconductor nanoparticles is a potential feature which can be interesting for photocatalysis, and cadmium selenide is one simple type of quantum dot to use in the following photocatalytic degradation of organic dyes. CdSe nanoparticles capped with polyvinylpyrrolidone (PVP in various concentration ratios were synthesized by the chemical reduction method and characterized. The transmission electron microscopy (TEM analysis of the samples showed that 50% PVP-capped CdSe nanoparticles were uniformly distributed in size with an average of 2.7 nm and shape which was spherical-like. The photocatalytic degradation of methyl blue (MB in water showed efficiencies of 31% and 48% when using uncapped and 50% PVP-capped CdSe nanoparticles as photocatalysts, respectively. The efficiency of PVP-capped CdSe nanoparticles indicated that a complete green process can be utilized for photocatalytic treatment of water and waste water.

  16. A short review on photocatalytic degradation of formaldehyde

    Tasbihi, M.; Bendyna, J.K.; Notten, P.H.L.; Hintzen, H.T.J.M.

    2015-01-01

    Nowadays, it is a great challenge to eliminate toxic and harmful organic pollutants from air and water. This paper reviews the role of TiO2 as a photocatalyst, light source and photoreactor in the particular case of removal of formaldehyde using the photocatalytic reaction by titanium dioxide (TiO2

  17. Photocatalytic Degradation of Malachite Green Using Nano-sized cerium-iron Oxide

    K. L. Ameta

    2014-05-01

    Full Text Available Nano-sized cerium-iron oxide nanoparticles has been synthesized, characterized and explored as an efficient photocatalyst for the photocatalytic degradation of malachite green. The effects of different variables on degradation of dye were optimized such as the pH of the dye solution, dye concentration, amount of photocatalyst and light intensity. About 91% degradation of dye of 2×10-5 M concentration was observed after 2 hours at 8.5 pH and 600 Wm-2 light intensity. The reason for the high catalytic activity of the synthesized nanoparticles is ascribed to the high surface area which determines the active sites of the catalyst and accelerates the photocatalytic degradation.

  18. Bi2WO6 nanoflowers: An efficient visible light photocatalytic activity for ceftriaxone sodium degradation

    Zhao, Yanyan; Wang, Yongbo; Liu, Enzhou; Fan, Jun; Hu, Xiaoyun

    2018-04-01

    The morphology-controlled synthesis of nano-structure photocatalyst have leaded a new possibility to improve their physical and chemical properties. Herein, Bi2WO6 nanocrystals (BWO) with nano-flower, nano plates, knot shape, rod like and irregular morphologies have been successfully synthesized through a highly facile hydrothermal process by simply adjusting pH values, reactive solvents and temperature. Photocatalytic activity of the as-prepared samples were evaluated by degradation of Ceftriaxone sodium under visible light irradiation (λ > 420 nm), the results indicated that all the BWO samples exhibit morphology-associated photocatalytic activity, and the 3D flowerlike-structure of BWO composed of well-ordered nano plates (BWO-D-5) displayed the outstanding photocatalytic activity. Through getting insight into the mechanism, h+ and rad O2- play major roles compared with rad OH in photocatalytic degradation process. The possible pathway of Ceftriaxone sodium and the intermediates were proposed to better understand the reaction process. Moreover, this work not only provides an example of morphology-dependent photocatalytic activity of BWO but also provides an illustrative example for removing organic pollutant molecules according to practical requirements.

  19. Synthesis and properties of Ag/ZnO/g-C3N4 ternary micro/nano composites by microwave-assisted method

    Zhang, Zijie; Li, Xuexue; Chen, Haitao; Shao, Gang; Zhang, Rui; Lu, Hongxia

    2018-01-01

    Ag/ZnO/g-C3N4 ternary micro/nanocomposites, as novel visible-light-driven photocatalysts, were prepared by a simple and convenient microwave-assisted method. The resulting ternary structure micro/nano composites were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy and infrared radiation techniques to examine its phase structure, valence state, morphological, thermal and optical properties. Well crystallized Ag/ZnO/g-C3N4 ternary micro/nano composites were synthesized under microwave-radiation for 15 min with the output of 240 W. Further experiments indicated Ag(5.0mol%)/ZnO/g-C3N4 photocatalyst in degradation of methylene blue exhibited an outstanding photocatalytic activity and its reaction rate constant (k, 0.0084 min-1) is 7.5, 2.4 2.9 and 3.5 times higher than that of monolithic ZnO (k, 0.0011 min-1), ZnO/g-C3N4(k, 0.0035 min-1), Ag(5 mol%)/ZnO(k, 0.0029 min-1) and Ag(5mol%)/g-C3N4 (k, 0.0024 min-1) respectively. Finally, a possible photocatalytic mechanism of Ag/ZnO/g-C3N4 photocatalyst in degradation process was proposed. This work provides a feasible strategy to synthesize an efficient ZnO-based photocatalyst which combines structure and properties of different dimensional components and made this ternary system an exciting candidate for sunlight-driven photocatalytic water treatment.

  20. Photocatalytic degradation kinetics and mechanism of phenobarbital in TiO(2) aqueous solution.

    Cao, Hua; Lin, Xiulian; Zhan, Haiying; Zhang, Hong; Lin, Jingxin

    2013-01-01

    5-Ethyl-5-phenylpyrimidine-2,4,6(1H, 3H, 5H)-trione is an anti-convulsant used to treat disorders of movement, e.g. tremors. This work deals with the transformation of phenobarbital by UV/TiO(2) heterogeneous photocatalysis, to assess the decomposition of the pharmaceutical compound, to identify intermediates, as well as to elucidate some mechanistic details of the degradation. The photocatalytic removal efficiency of 100 μm phenobarbital is about 80% within 60 min, while the degradation efficiency of phenobarbital was better in alkaline solution. The study on contribution of reactive oxidative species (ROSs) has shown that ()OH is responsible for the major degradation of phenobarbital, while the photohole, photoelectrons and the other ROSs have the minor contribution to the degradation. Finally, based on the identification of degradation intermediates, two main photocatalytic degradation pathways have been tentatively proposed, including the hydroxylation and cleavage of pyrimidine ring in the phenobarbital molecule respectively. Certainly, the phenobarbital can be mineralized when the photocatalytic reaction time prolongs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Antibacterial and photocatalytic degradation efficacy of silver nanoparticles biosynthesized using Cordia dichotoma leaf extract

    Mankamna Kumari, R.; Thapa, Nikita; Gupta, Nidhi; Kumar, Ajeet; Nimesh, Surendra

    2016-12-01

    The present study focuses on the biosynthesis of silver nanoparticles (AgNPs) along with its antibacterial and photocatalytic activity. The AgNPs were synthesized using Cordia dichotoma leaf extract and were characterized using UV-vis spectroscopy to determine the formation of AgNPs. FTIR was done to discern biomolecules responsible for reduction and capping of the synthesized nanoparticles. Further, DLS technique was performed to examine its hydrodynamic diameter, followed by SEM, TEM and XRD to determine its size, morphology and crystalline structure. Later, these AgNPs were studied for their potential role in antibacterial activity and photocatalytic degradation of azo dyes such as methylene blue and Congo red.

  2. Photocatalytic degradation of malachite green dye using Au/NaNbO{sub 3} nanoparticles

    Baeissa, E.S., E-mail: elhambaeissa@gmail.com

    2016-07-05

    The morphology of sodium niobate, which was produced using a hydrothermal method, was studied by changing the hydrothermal temperature from 100 to 250 °C. Using 250 °C hydrothermal temperature resulted in sodium niobate with a nanocube structure. The sodium niobate nanocubes were doped with gold by impregnation with an aqueous solution of HAuCl{sub 4}. The band gap of sodium niobate is approximately 3.4 eV, and it was decreased to 2.45 eV by gold doping. The surface area of sodium niobate is higher than that of Au/NaNbO{sub 3} due to blockage of some pores of sodium niobate by gold doping. The photocatalytic performance of gold-doped sodium niobate was studied by degradation of malachite green dye using visible light irradiation. The results demonstrate that the photocatalytic performance of gold-doped sodium niobate is higher than that of sodium niobate and TiO{sub 2} Degussa under visible light irradiation. - Highlights: • Au/NaNbO{sub 3} were used for photocatalytic degradation of malachite green dye. • Photocatalytic degradation was dependent on wt % of Au; reaction time, and weight of catalyst. • Catalyst re-use revealed the present photocatalyst remain effective and active after five cycles.

  3. Photocatalytic degradation of textile dyestuffs using TiO{sub 2} nanotubes prepared by sonoelectrochemical method

    Tekin, Derya, E-mail: deryatekin@atauni.edu.tr

    2014-11-01

    Highlights: • TiO{sub 2} nanotubes prepared by electrochemical and sonoelectrochemical method. • More regular TiO{sub 2} nanotubes diameters prepared by sonoelectrochemical method. • Obtained nanotubes were used in the photocatalytic degradation of Orange G dye. • TiO{sub 2} nanotubes prepared by sonoelectrochemical method showed 10% faster degradation of Orange G dye compared with the one by electrochemical method. - Abstract: TiO{sub 2} nanotubes were prepared by anodization of Ti plates by conventional electrochemical technique as well as by an emerging sonoelectrochemical technique. Scanning electron miscroscope (SEM) analysis showed that ultrasound assisted anodization yielded more ordered and controllable TiO{sub 2} tube banks with higher tube diameter. The photocatalytical activities of TiO{sub 2} nanotubes were tested in the photocatalytical degradation of Orange G dye. The results showed that sonoelectrochemically prepared TiO{sub 2} tubes exhibited 10% higher photocatalytic performance than the electrochemical prepared ones, and more than 18% higher activity than the other TiO{sub 2} samples.

  4. Photocatalytic degradation of malachite green dye using Au/NaNbO_3 nanoparticles

    Baeissa, E.S.

    2016-01-01

    The morphology of sodium niobate, which was produced using a hydrothermal method, was studied by changing the hydrothermal temperature from 100 to 250 °C. Using 250 °C hydrothermal temperature resulted in sodium niobate with a nanocube structure. The sodium niobate nanocubes were doped with gold by impregnation with an aqueous solution of HAuCl_4. The band gap of sodium niobate is approximately 3.4 eV, and it was decreased to 2.45 eV by gold doping. The surface area of sodium niobate is higher than that of Au/NaNbO_3 due to blockage of some pores of sodium niobate by gold doping. The photocatalytic performance of gold-doped sodium niobate was studied by degradation of malachite green dye using visible light irradiation. The results demonstrate that the photocatalytic performance of gold-doped sodium niobate is higher than that of sodium niobate and TiO_2 Degussa under visible light irradiation. - Highlights: • Au/NaNbO_3 were used for photocatalytic degradation of malachite green dye. • Photocatalytic degradation was dependent on wt % of Au; reaction time, and weight of catalyst. • Catalyst re-use revealed the present photocatalyst remain effective and active after five cycles.

  5. Sequential reduction–oxidation for photocatalytic degradation of tetrabromobisphenol A: Kinetics and intermediates

    Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei; Wang, Zhaohui; Liu, Jianshe

    2012-01-01

    Highlights: ► Sequential photocatalytic reduction–oxidation degradation of TBBPA was firstly examined. ► Different atmospheres were found to have significant effect on debromination reaction. ► A possible sequential photocatalytic reduction–oxidation pathway was proposed. - Abstract: C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC–MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N 2 -saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO 2 system by changing the reaction atmospheres.

  6. Physical principles of microwave assisted magnetic recording

    Rivkin, Kirill; Benakli, Mourad; Yin, Huaqing; Tabat, Ned

    2014-01-01

    While the basic physics of Microwave Assisted Magnetization Reversal (MAMR) phenomenon is well established both theoretically and experimentally, its application in a practical magnetic recording environment was so far studied primarily with the help of micromagnetic recording models. In this work, we instead attempt to use analytical formulation and simple numerical models to understand the main challenges as well as benefits that are associated with such a system. It appears that the main difference between the previously introduced theory [G. Bertotti et al., Phys. Rev. Lett. 86, 724 (2001); K. Rivkin et al., Appl. Phys. Lett. 92, 153104 (2008); S. Okamoto et al., J. Appl. Phys. 107, 123914 (2010).] and recording environment is that both the RF and DC magnetic fields are applied at a substantial angle to the anisotropy axis. While the associated symmetry breaking prevents one from describing the reversal process explicitly, it is possible to approximate the solutions well enough to satisfactorily match numerical models both in the case of wire and Spin Torque Oscillator generated RF fields. This approach allows for physical explanation of various effects associated with MAMR such as high gradient of writeable anisotropy and reduction of track width, and offers a clear guidance regarding future optimization of MAMR recording.

  7. Physical principles of microwave assisted magnetic recording

    Rivkin, Kirill; Benakli, Mourad; Yin, Huaqing [Seagate Technology, Edina, Minnesota 55435 (United States); Tabat, Ned [Semaphore Scientific Inc., Chanhassen, Minnesota 55317 (United States)

    2014-06-07

    While the basic physics of Microwave Assisted Magnetization Reversal (MAMR) phenomenon is well established both theoretically and experimentally, its application in a practical magnetic recording environment was so far studied primarily with the help of micromagnetic recording models. In this work, we instead attempt to use analytical formulation and simple numerical models to understand the main challenges as well as benefits that are associated with such a system. It appears that the main difference between the previously introduced theory [G. Bertotti et al., Phys. Rev. Lett. 86, 724 (2001); K. Rivkin et al., Appl. Phys. Lett. 92, 153104 (2008); S. Okamoto et al., J. Appl. Phys. 107, 123914 (2010).] and recording environment is that both the RF and DC magnetic fields are applied at a substantial angle to the anisotropy axis. While the associated symmetry breaking prevents one from describing the reversal process explicitly, it is possible to approximate the solutions well enough to satisfactorily match numerical models both in the case of wire and Spin Torque Oscillator generated RF fields. This approach allows for physical explanation of various effects associated with MAMR such as high gradient of writeable anisotropy and reduction of track width, and offers a clear guidance regarding future optimization of MAMR recording.

  8. Microwave assisted synthesis of hydroxyapatite nano strips

    Ruban Kumar, A.; Kalainathan, S.; Saral, A.M. [School of Advanced Sciences, VIT University, Vellore 632014, Tamil Nadu (India)

    2010-07-15

    Synthesis of hydroxyapatite (HAP) nano strips was carried out by chemical precipitation method followed by microwave irradiation. The microwave assisted reactions proceed at fast rates. It is found that the presence of the complex reagent EDTA plays an important role in the morphological changes of nanostructure hydroxyapatite. EDTA acts as a hexadentate unit by wrapping itself around the Ca{sup 2+} metal ion with, four oxygen and two nitrogen atoms and forms several five member chelate rings. The relative specific surface energies associated with the facets of the crystal determines the shape of the crystal. Scanning electron microscopy revealed the presence of hydroxyapatite nano strips with the range 50-100 nm in EDTA influenced HAP powders. Fourier transform-infrared spectroscopy (FT-IR) result combined with the X-ray diffraction (XRD) indicates the presence of amorphous hydroxyapatite (HAP) in the as-prepared material. X-ray patterns collected on the powder after heat-treatment at 1100 C for 2 h in air exhibits single phase of HAP. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Microwave-assisted green synthesis and antimicrobial activity of ...

    Microwave-assisted green synthesis and antimicrobial activity of silver nanoparticles derived from a ... Journal Home > Vol 16, No 12 (2017) > ... has been prepared by a simple, eco-friendly, cost-effective, rapid green chemistry methodology.

  10. Application of Titanium Dioxide-Graphene Composite Material for Photocatalytic Degradation of Alkylphenols

    Chanbasha Basheer

    2013-01-01

    Full Text Available Titanium dioxide-graphene (TiO2-G composite was used for the photodegradation of alkylphenols in wastewater samples. The TiO2-G composites were prepared via sonochemical and calcination methods. The synthesized composite was characterized by X-ray diffraction (XRD, infrared spectroscopy (IR, scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive X-ray analysis (EDX, and fluorescence spectroscopy. The photocatalytic efficiency was evaluated by studying the degradation profiles of alkylphenols using gas chromatography-flame ionization detector (GC-FID. It was found that the synthesized TiO2-G composites exhibit enhanced photocatalytic efficiencies as compared to pristine TiO2. The presence of graphene not only provides a large surface area support for the TiO2 photocatalyst, but also stabilizes charge separation by trapping electrons transferred from TiO2, thereby hindering charge transfer and enhancing its photocatalytic efficiency.

  11. Microwave-Assisted Synthesis of Phenothiazine and Quinoline Derivatives

    Găină, Luiza; Cristea, Castelia; Moldovan, Claudia; Porumb, Dan; Surducan, Emanoil; Deleanu, Călin; Mahamoud, Abdalah; Barbe, Jacques; Silberg, Ioan A.

    2007-01-01

    Application of a dynamic microwave power system in the chemical synthesis of some phenothiazine and quinoline derivatives is described. Heterocyclic ring formation, aromatic nucleophilic substitution and heterocyclic aldehydes/ketones condensation reactions were performed on solid support, or under solvent free reaction conditions. The microwave-assisted Duff formylation of phenothiazine was achieved. Comparison of microwave-assisted synthesis with the conventional synthetic methods demonstrates advantages related to shorter reaction times and in some cases better reaction yields.

  12. Enhanced visible light photocatalytic degradation of methylene blue by F-doped TiO{sub 2}

    Yu, Wei [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Center for Coordination Bond and Electronic Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Li, Jinliang; Liu, Junying [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Zhang, Jing; Li, Ping; Chen, Chen [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2014-11-15

    Graphical abstract: F-doped TiO2 is synthesized using a modified sol–gel method for visible photocatalytic degradation of MB with a high degradation rate of 91%. - Highlights: • F-doped TiO{sub 2} are synthesized using a modified sol–gel method. • The photocatalytic degradation of methylene blue by F-doped TiO{sub 2} is investigated. • A high methylene blue degradation rate of 91% is achieved under visible light irradiation. - Abstract: F-doped TiO{sub 2} (F-TiO{sub 2}) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO{sub 2} exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO{sub 2} (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO{sub 2}.

  13. Ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 by using Nb2O5 nano catalyst

    Gunvant H. Sonawane

    2016-09-01

    Full Text Available The ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 accompanied by Nb2O5 nano catalysts were studied. The structure and morphology of synthesized Nb2O5 nano catalyst was investigated using scanning election microscopy (SEM, Electron dispersive X-ray spectroscopy (EDS and X-ray diffraction (XRD.The effects of various experimental parameters such as the Basic Red-2 concentration, catalyst dose, pH and addition of H2O2 on the ultrasonic, photocatalytic and sonophotocatalytic degradation were investigated. Photocatalytic and sonophotocatalytic degradation of Basic Red-2 was strongly affected by initial dye concentration, catalyst dose, H2O2 addition and pH. Basic pH (pH-10 was favored for the ultrasonic (US, photocatalytic (UV + Nb2O5 and sonophotocatalytic (US + UV + Nb2O5 degradation of Basic Red-2 by using Nb2O5 nano catalyst. The ultrasonic degradation of Basic Red-2 was enhanced by the addition of photocatalyst. Then, the effect of Nb2O5 dose on photocatalytic and sonophotocatalytic degradation were studied, and it was found that increase in catalyst dose increase in the percentage degradation of Basic Red-2. In addition, the effects of H2O2 on ultrasonic, photolytic, photocatalytic and sonophotocatalytic degradation was also investigated, and it was found that H2O2 enhances the % degradation of Basic Red-2. The possible mechanism of ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 reported by LC-MS shows generation of different degradation products

  14. Synthesis of metal free ultrathin graphitic carbon nitride sheet for photocatalytic dye degradation of Rhodamine B under visible light irradiation

    Rahman, Shakeelur; Momin, Bilal; Higgins M., W.; Annapure, Uday S.; Jha, Neetu

    2018-04-01

    In recent times, low cost and metal free photocatalyts driven under visible light have attracted a lot of interest. One such photo catalyst researched extensively is bulk graphitic carbon nitride sheets. But the low surface area and weak mobility of photo generated electrons limits its photocatalytic performance in the visible light spectrum. Here we present the facile synthesis of ultrathin graphitic carbon nitride using a cost effective melamine precursor and its application in highly efficient photocatalytic dye degradation of Rhodamine B molecules. Compared to bulk graphitic carbon nitride, the synthesized ultrathin graphitic carbon nitride shows an increase in surface area, a a decrease in optical band gap and effective photogenerated charge separation which facilitates the harvest of visible light irradiation. Due to these optimal properties of ultrathin graphitic carbon nitride, it shows excellent photocatalytic activity with photocatalytic degradation of about 95% rhodamine B molecules in 1 hour.

  15. Preparation and photocatalytic degradation performance of Ag_3PO_4 with a two-step approach

    Li, Jiwen; Ji, Xiaojing; Li, Xian; Hu, Xianghua; Sun, Yanfang; Ma, Jingjun; Qiao, Gaowei

    2016-01-01

    Highlights: • Ag_3PO_4 photocatalysts were synthesized via one-step and two-step ion-exchange reaction. • Photocatalytic properties of Ag_3PO_4 photocatalysts was investigated, the result indicated the Ag_3PO_4 (2) was higher than that of Ag_3PO_4 (1) under the same experimental condition. • Ag_3PO_4 (2) particles were larger than Ag_3PO_4 (1) particles and many polygonal-shaped surfaces could be clearly observed in the Ag_3PO_4 (2) particles. - Abstract: Ag_3PO_4 photocatalysts were prepared via two and one-step through a facile ion-exchange route. The photocatalysts were then characterized through powder X-ray diffraction, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated on the basis of the photocatalytic degradation of methyl orange (MO) and methylene blue (MB) under solar irradiation. The MO degradation rate of the Photocatalyst synthesized by the two-step ion-exchange route was 89.18% in 60 min. This value was four times that of the Photocatalyst synthesized by the one-step approach.The MB degradation rate was 97% in 40 min. After six cycling runs were completed, the MO degradation rate was 73%

  16. Efficient photocatalytic degradation of phenol in aqueous solution by SnO2:Sb nanoparticles

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Bora, Tanujjal; Dutta, Joydeep

    2016-01-01

    Highlights: • Sb doped SnO 2 nanoparticles were synthesized using sol–gel process. • Photocatalytic degradation of phenol were studies using SnO 2 :Sb nanoparticles. • Under solar light phenol was degraded within 2 h. • Phenol mineralization and intermediates were investigated by using HPLC. - Abstract: Photodegradation of phenol in the presence of tin dioxide (SnO 2 ) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO 2 . In this study antimony (Sb) doped tin dioxide (SnO 2 ) nanoparticles were prepared at a low temperature (80 °C) by a sol–gel method and studied for its photocatalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO 2 :Sb was found to be a maximum for 0.6 wt.% Sb doped SnO 2 nanoparticles with 10 mg L −1 phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  17. Efficient photocatalytic degradation of phenol in aqueous solution by SnO{sub 2}:Sb nanoparticles

    Al-Hamdi, Abdullah M., E-mail: Abdullah.Al.Hamdi@lut.fi [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Chemistry Department, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Bora, Tanujjal [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Dutta, Joydeep [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman); Functional Materials Division, ICT, KTH Royal Institute of Technology, Isafjordsgatan 22, SE-164 40 KistaStockholm (Sweden)

    2016-05-01

    Highlights: • Sb doped SnO{sub 2} nanoparticles were synthesized using sol–gel process. • Photocatalytic degradation of phenol were studies using SnO{sub 2}:Sb nanoparticles. • Under solar light phenol was degraded within 2 h. • Phenol mineralization and intermediates were investigated by using HPLC. - Abstract: Photodegradation of phenol in the presence of tin dioxide (SnO{sub 2}) nanoparticles under UV light irradiation is known to be an effective photocatalytic process. However, phenol degradation under solar light is less effective due to the large band gap of SnO{sub 2}. In this study antimony (Sb) doped tin dioxide (SnO{sub 2}) nanoparticles were prepared at a low temperature (80 °C) by a sol–gel method and studied for its photocatalytic activity with phenol as a test contaminant. The catalytic degradation of phenol in aqueous media was studied using high performance liquid chromatography and total organic carbon measurements. The change in the concentration of phenol affects the pH of the solution due to the by-products formed during the photo-oxidation of phenol. The photoactivity of SnO{sub 2}:Sb was found to be a maximum for 0.6 wt.% Sb doped SnO{sub 2} nanoparticles with 10 mg L{sup −1} phenol in water. Within 2 h of photodegradation, more than 95% of phenol could be removed under solar light irradiation.

  18. New porous titanium–niobium oxide for photocatalytic degradation of bromocresol green dye in aqueous solution

    Chaleshtori, Maryam Zarei, E-mail: mzarei@utep.edu [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Hosseini, Mahsa; Edalatpour, Roya [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Masud, S.M. Sarif [Department of Chemistry, University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States); Chianelli, Russell R., E-mail: chianell@utep.edu [Materials Research and Technology Institute (MRTI), University of Texas at El Paso, 500W. University Ave., El Paso, TX 79968 (United States)

    2013-10-15

    Graphical abstract: The photocatalytic activity of different porous titanium–niobium oxides was evaluated toward degradation of bromocresol green (BG) under UV light. A better catalytic activity was observed for all samples at lower pH. Catalysts have a stronger ability for degradation of BG in acid media than in alkaline media. - Highlights: • Different highly structured titanium–niobium oxides have been prepared using improved methods of synthesis. • Photo-degradation of bromocresol green dye (BG) with nanostructure titanium–niobium oxide catalysts was carried out under UV light. • The photo-catalytic activity of all catalysts was higher in lower pH. • Titanium–niobium oxide catalysts are considerably stable and reusable. - Abstract: In this study, high surface area semiconductors, non porous and porous titanium–niobium oxides derived from KTiNbO{sub 5} were synthesized, characterized and developed for their utility as photocatalysts for decontamination with sunlight. These materials were then used in the photocatalytic degradation of bromocresol green dye (BG) in aqueous solution using UV light and their catalytic activities were evaluated at various pHs. For all catalysts, the photocatalytic degradation of BG was most efficient in acidic solutions. Results show that the new porous oxides have large porous and high surface areas and high catalytic activity. A topotactic dehydration treatment greatly improves catalyst performance at various pHs. Stability and long term activity of porous materials (topo and non-topo) in photocatalysis reactions was also tested. These results suggest that the new materials can be used to efficiently purify contaminated water.

  19. Biosensor-based real-time monitoring of paracetamol photocatalytic degradation.

    Calas-Blanchard, Carole; Istamboulié, Georges; Bontoux, Margot; Plantard, Gaël; Goetz, Vincent; Noguer, Thierry

    2015-07-01

    This paper presents for the first time the integration of a biosensor for the on-line, real-time monitoring of a photocatalytic degradation process. Paracetamol was used as a model molecule due to its wide use and occurrence in environmental waters. The biosensor was developed based on tyrosinase immobilization in a polyvinylalcohol photocrosslinkable polymer. It was inserted in a computer-controlled flow system installed besides a photocatalytic reactor including titanium dioxide (TiO2) as photocatalyst. It was shown that the biosensor was able to accurately monitor the paracetamol degradation with time. Compared with conventional HPLC analysis, the described device provides a real-time information on the reaction advancement, allowing a better control of the photodegradation process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Photocatalytic degradation of trichloroethylene: influence of trichloroethylene and TiO/sub 2/ concentrations

    Farooq, M.; Raja, I.A.

    2005-01-01

    Industrial wastewater streams usually contain highly toxic pollutants, cyanides, chlorinated compounds such as trichloroethylene (TCE) etc. The heterogeneous photocatalysis is more efficient technique other than traditionally employed methods used for detoxification of wastewater. The paper describes photocatalytic degradation of trichloroethylene in aqueous solution using TiO/sub 2/. Variable parameters such as initial concentration of TCE, concentration of TiO/sub 2/ and time were investigated. The TCE contaminated water was circulated in the reactor to expose it to UV radiation. The circulation speed and UV radiation intensity was kept constant. The photocatalytic degradation rate increased with increasing the initial concentration of TCE, but beyond the certain limit, 45 micro l of TCE per litter of water the rate started decreasing. (author)

  1. Enhancing Photocatalytic Degradation of Methyl Blue Using PVP-Capped and Uncapped CdSe Nanoparticles

    Chepape, Kgobudi Frans; Mofokeng, Thapelo Prince; Nyamukamba, Pardon; Mubiayi, Kalenga Pierre; Moloto, Makwena Justice

    2017-01-01

    Quantum confinement of semiconductor nanoparticles is a potential feature which can be interesting for photocatalysis, and cadmium selenide is one simple type of quantum dot to use in the following photocatalytic degradation of organic dyes. CdSe nanoparticles capped with polyvinylpyrrolidone (PVP) in various concentration ratios were synthesized by the chemical reduction method and characterized. The transmission electron microscopy (TEM) analysis of the samples showed that 50% PVP-capped Cd...

  2. Synthesis of Nickel Oxide Nanoparticles Using Gelatine as a Green Template for Photocatalytic Degradation of Dye

    JAY YANG LEE

    2018-01-01

    Nickel oxide (NiO) nanoparticles were synthesized through sol-gel method with an environmentally friendly templating agent, which is gelatin. The synthesized NiO were characterized to determine the chemical and physical properties of the nanoparticles. The optimum synthesis parameters were used in photocatalytic degradation of Reactive Black 5 and Acid Yellow 25 dye to determine the catalytic activity of the nanoparticles.

  3. Enhanced photocatalytic degradation of Safranin-O by heterogeneous nanoparticles for environmental applications

    El-Kemary, Maged; Abdel-Moneam, Yasser; Madkour, Metwally; El-Mehasseb, Ibrahim

    2011-01-01

    Nanostructure titanium dioxide (TiO 2 ) has been synthesized by hydrolysis of titanium tetrachloride in aqueous solution and Ag-TiO 2 nanoparticles were synthesized by photoreduction method. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared (FT-IR) and UV-vis absorption spectroscopy. The experimental results showed that the sizes of the synthesized TiO 2 and Ag-TiO 2 particles are in the range of 1.9-3.2 nm and 2-10 nm, respectively. Moreover, Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . The positive effect of silver on the photocatalytic activity of TiO 2 may be explained by its ability to trap electrons. This process reduces the recombination of light generated electron-hole pairs at TiO 2 surface and therefore enhances the photocatalytic activity of the synthesized TiO 2 nanoparticles. The effects of initial dye and nanoparticle concentrations on the photocatalytic activity have been studied and the results demonstrate that the dye photodegradation follows pseudo-first-order kinetics. The observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 . - Research highlights: → Ag-TiO 2 nanoparticles exhibit enhanced photocatalytic activity on photodegradation of Safranin-O (SO) dye as compared to pure TiO 2 . → Dye photodegradation follows pseudo-first-order kinetics. → Observed maximum degradation efficiency of SO is about 60% for TiO 2 and 96% for Ag-TiO 2 .

  4. Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste.

    Sarkar, Santanu; Bhattacharjee, Chiranjib; Curcio, Stefano

    2015-11-01

    The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Photocatalytic performance of graphene/TiO_2-Ag composites on amaranth dye degradation

    Roşu, Marcela-Corina; Socaci, Crina; Floare-Avram, Veronica; Borodi, Gheorghe; Pogăcean, Florina; Coroş, Maria; Măgeruşan, Lidia; Pruneanu, Stela

    2016-01-01

    Ternary nanocomposites containing TiO_2, silver and graphene with different reduction levels were prepared and used as photocatalysts for amaranth azo dye degradation, under UV and natural light exposure. The obtained materials were characterized by TEM, XRD, FTIR and UV-Vis spectroscopy, confirming the successful formation of the nanocomposites. HPLC analysis along with UV-Vis spectroscopy were employed to quantify the concentration of non-degraded dye in solution. The graphene/TiO_2-Ag nanocomposites proved to have remarkable photocatalytic activities for amaranth degradation under UV and solar irradiation (85.3–98% of dye has disappeared in the first 2 h). Also, significant removal efficiencies (between 40.5 and 71.8%) of photocatalysts, in day light conditions, were demonstrated. The best result for amaranth dye degradation was obtained with the reduced graphene/TiO_2-Ag catalyst (up to 99.9%). Based on the degradation products analysis, a photodegradation pathway of amaranth dye was also proposed. - Highlights: • Graphene/TiO_2-Ag composites were prepared by a combined chemical-thermal method. • The composites showed improved light-absorption characteristics. • A significant degradation performance of amaranth was obtained with these composites under UV and natural light exposure. • Graphene/TiO_2-Ag composites offer a high potential for various photocatalytic applications in pollutant removal processes.

  6. Photocatalytic performance of graphene/TiO{sub 2}-Ag composites on amaranth dye degradation

    Roşu, Marcela-Corina, E-mail: marcela.rosu@itim-cj.ro; Socaci, Crina; Floare-Avram, Veronica; Borodi, Gheorghe; Pogăcean, Florina; Coroş, Maria; Măgeruşan, Lidia; Pruneanu, Stela

    2016-08-15

    Ternary nanocomposites containing TiO{sub 2}, silver and graphene with different reduction levels were prepared and used as photocatalysts for amaranth azo dye degradation, under UV and natural light exposure. The obtained materials were characterized by TEM, XRD, FTIR and UV-Vis spectroscopy, confirming the successful formation of the nanocomposites. HPLC analysis along with UV-Vis spectroscopy were employed to quantify the concentration of non-degraded dye in solution. The graphene/TiO{sub 2}-Ag nanocomposites proved to have remarkable photocatalytic activities for amaranth degradation under UV and solar irradiation (85.3–98% of dye has disappeared in the first 2 h). Also, significant removal efficiencies (between 40.5 and 71.8%) of photocatalysts, in day light conditions, were demonstrated. The best result for amaranth dye degradation was obtained with the reduced graphene/TiO{sub 2}-Ag catalyst (up to 99.9%). Based on the degradation products analysis, a photodegradation pathway of amaranth dye was also proposed. - Highlights: • Graphene/TiO{sub 2}-Ag composites were prepared by a combined chemical-thermal method. • The composites showed improved light-absorption characteristics. • A significant degradation performance of amaranth was obtained with these composites under UV and natural light exposure. • Graphene/TiO{sub 2}-Ag composites offer a high potential for various photocatalytic applications in pollutant removal processes.

  7. The impact of alkali metal halide electron donor complexes in the photocatalytic degradation of pentachlorophenol

    Khuzwayo, Z., E-mail: zack.khuzwayo@up.ac.za; Chirwa, E.M.N

    2017-01-05

    Highlights: • Facilitation of photocatalysis using simple metal-halides as VB hole scavengers. • Recombination prevention by coupled valence and conduction band approaches. • Determination of anions critical levels beyond which process retardation occurs. • Determination of the photocatalytic process rate of reaction kinetics. - Abstract: The performance of photocatalytic oxidation of chemical pollutants is subjected to the presence of anion complexes in natural waters. This study investigated the influence of alkali metal (Na{sup +} (sodium), K{sup +} (potassium)) halides (Cl{sup −} (chloride), Br{sup −} (bromide), F{sup −} (fluoride)) as inorganic ion sources in the photocatalytic degradation of pentachlorophenol (PCP) in batch systems. It was found that the exclusive presence of halides in the absence of an electron acceptor adequately facilitated the photocatalyst process below critical levels of anion populations, where beyond the critical point the process was significantly hindered. Below the determined critical point, the performance in some cases near matches that of the facilitation of the photocatalytic process by exclusive oxygen, acting as an electron scavenger. The coupling of halide ions and oxygenation presented significantly improved photo-oxidation of PCP, this was confirmed by the inclusion of formic acid as a comparative electron donor. The Langmuir-Hinshelwood kinetic expression was used to calculate the performance rate kinetics. The probable impact of the halide anions was discussed with regards to the process of electron hole pair recombination prevention.

  8. TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

    Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

    2016-01-01

    This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features. PMID:28773634

  9. TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

    Alberto Strini

    2016-06-01

    Full Text Available This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin, composite systems (siloxane-hybrid, foamed hybrid, and curing temperatures (room temperature and 60 °C were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste. The geopolymer matrices were previously designed for different applications, ranging from insulating (foam to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM and energy dispersive X-ray (EDS analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

  10. Rapid synthesis of nitrogen doped titania with mixed crystal lattice via microwave-assisted hydrothermal method

    Zhang Peilin; Liu Bin; Yin Shu; Wang Yuhua; Petrykin, Valery; Kakihana, Masato; Sato, Tsugio

    2009-01-01

    A microwave-assisted hydrothermal method was employed to synthesize nitrogen doped titania nanoparticles. Due to the high heating efficiency of microwave, rapid synthesis could be achieved in comparison with the conventional oven. Mixed crystal lattice was found existing in the obtained product, and the phase transformation behaviour under calcination was studied by XRD measurement together with Raman spectroscopy in details. The obtained nitrogen doped titania showed high specific surface area, about 300 m 2 g -1 . Photocatalytic activity in destructing NO x gas by the prepared sample exceeded that of commercial titania (P 25) or nitrogen doped titania synthesized by conventional hydrothermal method, under both visible-light and ultraviolet-light irradiation.

  11. Photocatalytic degradation of paracetamol: intermediates and total reaction mechanism.

    Moctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A; Luna, Raúl A; Montalvo, Carlos

    2012-12-01

    The advanced oxidation of paracetamol (PAM) promoted by TiO(2)/UV system in aqueous medium was investigated. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidation of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixtures. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the aromatic amide present in PAM and subsequent formation of several aromatic intermediate compounds such as p-aminophenol and p-nitrophenol. These aromatic compounds were eventually converted into trans-unsaturated carboxylic acids. Based on these experimental results, an alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Photocatalytic degradation of sulfamethoxazole in aqueous solution using a floating TiO2-expanded perlite photocatalyst

    Długosz, Maciej; Żmudzki, Paweł; Kwiecień, Anna; Szczubiałka, Krzysztof; Krzek, Jan; Nowakowska, Maria

    2015-01-01

    Highlights: • Sulfamethoxazole was degraded using a floating photocatalyst under UV irradiation. • The photocatalyst was obtained by supporting TiO 2 onto expanded perlite. • The mechanism of sulfamethoxazole photodegradation in water was proposed. • The photodegradation rate of sulfamethoxazole is greater at higher pH. - Abstract: Photocatalytic degradation of an antibiotic, sulfamethoxazole (SMX), in aqueous solution using a novel floating TiO 2 -expanded perlite photocatalyst (EP-TiO 2 -773) and radiation from the near UV spectral range was studied. The process is important considering that SMX is known to be a widespread and highly persistent pollutant of water resources. SMX degradation was described using a pseudo-first-order kinetic equation according to the Langmuir–Hinshelwood model. The products of the SMX photocatalytic degradation were identified. The effect of pH on the kinetics and mechanism of SMX photocatalytic degradation was explained

  13. Photocatalytic degradation of sulfamethoxazole in aqueous solution using a floating TiO{sub 2}-expanded perlite photocatalyst

    Długosz, Maciej [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Żmudzki, Paweł; Kwiecień, Anna [Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków (Poland); Szczubiałka, Krzysztof, E-mail: szczubia@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland); Krzek, Jan [Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków (Poland); Nowakowska, Maria, E-mail: nowakows@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland)

    2015-11-15

    Highlights: • Sulfamethoxazole was degraded using a floating photocatalyst under UV irradiation. • The photocatalyst was obtained by supporting TiO{sub 2} onto expanded perlite. • The mechanism of sulfamethoxazole photodegradation in water was proposed. • The photodegradation rate of sulfamethoxazole is greater at higher pH. - Abstract: Photocatalytic degradation of an antibiotic, sulfamethoxazole (SMX), in aqueous solution using a novel floating TiO{sub 2}-expanded perlite photocatalyst (EP-TiO{sub 2}-773) and radiation from the near UV spectral range was studied. The process is important considering that SMX is known to be a widespread and highly persistent pollutant of water resources. SMX degradation was described using a pseudo-first-order kinetic equation according to the Langmuir–Hinshelwood model. The products of the SMX photocatalytic degradation were identified. The effect of pH on the kinetics and mechanism of SMX photocatalytic degradation was explained.

  14. Photocatalytic degradation of sunscreen active ingredients mediated by nanostructured materials

    Soto-Vazquez, Loraine

    Water scarcity and pollution are environmental issues with terrible consequences. In recent years several pharmaceutical and personal care products, such as sunscreen active ingredients, have been detected in different water matrices. Its recalcitrant behavior in the environment has caused controversies and generated countless questions about its safety. During this research, we employed an advanced oxidation process (photocatalysis) to degrade sunscreen active ingredients. For this study, we used a 3x3 system, evaluating three photocatalysts and three different contaminants. From the three catalysts employed, two of them were synthesized. ZnO nanoparticles were obtained using zinc acetate dihydrated as the precursor, and TiO2 nanowires were synthesized from titanium tetrachloride precursor. The third catalyst employed (namely, P25) was obtained commercially. The synthesized photocatalysts were characterized in terms of the morphology, elemental composition, crystalline structure, elemental oxidation states, vibrational modes and surface area, using SEM-EDS, XRD, XPS, Raman spectroscopy and BET measurements, respectively. The photocatalysts were employed during the study of the degradation of p-aminobenzoic acid, phenylbenzimidazole sulfonic acid, and benzophenone-4. In all the cases, at least 50% degradation was achieved. P25 showed degradation efficiencies above 90%, and from the nine systems, 7 of them degraded at least 86%.

  15. Application of microwave assisted digestion in industrial hygiene

    Paudyn, A.M.; Smith, R.G.; Gawlowski, E.

    1990-01-01

    Microwave assisted digestion plays an important role in speeding up acquisition of analytical data for industrial hygiene purposes. This paper will compare hot plate and microwave assisted digestion for the determination of elements in industrial samples (air sampling filters, dusts, ashes, paints) by the ICPAES technique. Also, the determination of radionuclides in environmental samples (soils, sediments, rocks) by alpha, beta and gamma spectroscopy after the dissolution in a microwave oven will be presented. The results on the determination of elements in NIST standard reference materials and radionuclides in IAEA standards will be included. QC/QA protocols used in an occupational health laboratory setting will be discussed. Sample preparation using microwave assisted digestion proved not only to speed-up extraction of acid soluble elements, but also to achieve better recovery of some elements (Pb in paints) and give better reproducibility of determinations

  16. Au/ZnO nanocomposites: Facile fabrication and enhanced photocatalytic activity for degradation of benzene

    Yu, Hang; Ming, Hai; Zhang, Hengchao; Li, Haitao; Pan, Keming; Liu, Yang; Wang, Fang; Gong, Jingjing; Kang, Zhenhui

    2012-01-01

    Au nanoparticles supported on highly uniform one-dimensional ZnO nanowires (Au/ZnO hybrids) have been successfully fabricated through a simple wet chemical method, which were first used for photodegradation of gas-phase benzene. Compared with bare ZnO nanowires, the as-prepared Au/ZnO hybrids were found to possess higher photocatalytic activity for degradation of benzene under UV and visible light (degradation efficiencies reach about 56.0% and 33.7% after 24 h under UV and visible light irradiation, respectively). Depending on excitation happening on ZnO semiconductor or on the surface plasmon band of Au, the efficiency and operating mechanism are different. Under UV light irradiation, Au nanoparticles serve as an electron buffer and ZnO nanowires act as the reactive sites for benzene degradation. When visible light is used as the light irradiation source, Au nanoparticles act as the light harvesters and photocatalytic sites alongside of charge-transfer process, simultaneously. -- Graphical abstract: Under visible light irradiation, Au nanoparticles, which are supported on ZnO nanowires, dominate their catalytic properties in gas-phase degradation benzene reaction. Highlights: ► The composites that Au nanoparticles supported on ZnO nanowires were synthesized. ► Au/ZnO composites were firstly used as effective photocatalysts for benzene degradation. ► Two operating mechanisms were proposed depending on excitation wavelength.

  17. Enhanced Photocatalytic Performance of NiO-Decorated ZnO Nanowhiskers for Methylene Blue Degradation

    I. Abdul Rahman

    2014-01-01

    Full Text Available ZnO nanowhiskers were used for photodecomposition of methylene blue in aqueous solution under UV irradiation. The rate of methylene blue degradation increased linearly with time of UV irradiation. 54% of degradation rate was observed when the ZnO nanowhiskers were used as photocatalysts for methylene blue degradation for 80 min under UV irradiation. The decoration of p-type NiO nanoparticles on n-type ZnO nanowhiskers significantly enhanced photocatalytic activity and reached 72% degradation rate of methylene blue by using the same method. NiO-decorated ZnO was recycled for second test and shows 66% degradation from maximal peak of methylene blue within the same period. The increment of photocatalytic activity of NiO-decorated ZnO nanowhiskers was explained by the extension of the electron depletion layer due to the formation of nanoscale p-n junctions between p-type NiO and n-type ZnO. Hence, these products provide new alternative proficient photocatalysts for wastewater treatment.

  18. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  19. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Al-Hamdi, Abdullah M.; Sillanpää, Mika; Dutta, Joydeep

    2015-01-01

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO 2 :I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO 2 :I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO 2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO 2 nanoparticles under similar illumination conditions

  20. Photocatalytic degradation of tetracycline by Ti-MCM-41 prepared at room temperature and biotoxicity of degradation products

    Zhou, Kefu; Xie, Xiao-Dan; Chang, Chang-Tang

    2017-09-01

    Ti-doped MCM-41 with different Si/Ti molar ratios was prepared at room temperature to degrade tetracycline antibiotics in aqueous solution. The Ti was doped into the skeleton structure of MCM-41. The photocatalytic activity of Ti-doped MCM-41 was investigated. The optimal catalyst had Si/Ti molar ratio of 25 and over 99% removal of oxytetracycline in 150 min, and the removal could maintain 98% after 5 reuses. Ions and soluble organic matters in natural water affected the degradation reaction when Ti-doped MCM-41 was used to treat simulated wastewater of chicken farms. The degradation products of oxytetracycline, tetracycline and chlortetracycline were detected by Escherichia coli DH5α and HPLC-MS/MS. No intermediate product with higher toxicity was detected.

  1. Self-floating graphitic carbon nitride/zinc phthalocyanine nanofibers for photocatalytic degradation of contaminants

    Xu, Tiefeng; Ni, Dongjing; Chen, Xia; Wu, Fei; Ge, Pengfei; Lu, Wangyang, E-mail: luwy@zstu.edu.cn; Hu, Hongguang; Zhu, ZheXin; Chen, Wenxing, E-mail: wxchen@zstu.edu.cn

    2016-11-05

    Highlights: • A facile synthetic strategy to prepare visible-light responsive electrospun nanofibers. • Self-floating nanofiber photocatalyts for the effective utilization of solar. • Possible degradation pathway of RhB and CBZ under visible light and solar irradiation. • Present a method for removing highly hazardous contaminants. - Abstract: The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C{sub 3}N{sub 4}/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C{sub 3}N{sub 4}/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C{sub 3}N{sub 4}/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules.

  2. Magnetic and photocatalytic response of Ag-doped ZnFeO nano-composites for photocatalytic degradation of reactive dyes in aqueous solution

    Mahmood, Asif; Ramay, Shahid Mahmood; Al-Zaghayer, Yousef S.; Imran, Muhammad; Atiq, Shahid; Al-Johani, Meshal S.

    2014-01-01

    Highlights: • Self-consistent sol–gel based auto-combustion route was used. • Photocatalytic degradation of reactive dyes in aqueous solution was investigated. • Due to Ag doping, band gap reduced. • Activity of Ag-doped samples was higher than that of un-doped ones. - Abstract: To investigate the photocatalytic degradation of reactive dyes in aqueous solution, pure ZnO and Fe/Ag-doped magnetic photocatalysts having nominal compositions of Zn 0.95−x Fe 0.05 Ag x O (x = 0.0, 0.05 and 0.1) have been synthesized via self-consistent sol–gel based auto-combustion route. Thermally stable samples were subsequently confirmed to exhibit wurtzite type hexagonal structure, characteristic of ZnO. The nature of chemical bonding was elaborated by Fourier transform analysis. Electron microscopic techniques were employed to investigate the structural morphology and to evaluate the particle size. Ferromagnetic nature of the Fe/Ag doped samples was revealed by vibrating sample magnetometry, enabling the photocatalytic samples to be re-collected magnetically for repeated usage. The enhanced photocatalytic activity in the degradation of methylene blue under UV light irradiation with 5 and 10 wt.% Ag/ZnFeO has been observed validating the potential applications of these materials in the field of photo-degradation of organic pollutants

  3. The role played by different TiO2 features on the photocatalytic degradation of paracetamol

    Rimoldi, Luca; Meroni, Daniela; Falletta, Ermelinda; Ferretti, Anna Maria; Gervasini, Antonella; Cappelletti, Giuseppe; Ardizzone, Silvia

    2017-12-01

    Photocatalytic reactions promoted by TiO2 can be affected by a large number of oxide features (e.g. surface area, morphology and phase composition). In this context, the role played by the surface characteristics (e.g. surface acidity, wettability, etc.) has been often disregarded. In this work, pristine and Ta-doped TiO2 nanomaterials with different phase composition (pure anatase and anatase/brookite mixture) were synthesized by sol-gel and characterized under the structural and morphological point of view. A careful characterization of the acid properties of the materials has been performed by liquid-solid acid-base titration by means of 2-phenylethylamine (PEA) adsorption to determine the acid site density and average acid strength. Photocatalytic tests were performed in the degradation of paracetamol (acetaminophen) under UV irradiation and results were discussed in the light of the detailed scenarios describing the different oxides. The surface acidity of the samples, was recognized as one of the key parameters controlling the photocatalytic activity. A possible molecule degradation route is proposed on the ground of GC-MS and ESI-MS analyses.

  4. Multi-branched Cu2O nanowires for photocatalytic degradation of methyl orange

    Yu, Chunxin; Shu, Yun; Zhou, Xiaowei; Ren, Yang; Liu, Zhu

    2018-03-01

    Multi-branched cuprous oxide nanowires (Cu2O NWs) were prepared by one-step hydrothermal method of a facile process. The architecture of these Cu2O NWs was examined by scanning electron microscopy, and the resulting crystal nanowire consists of the trunk growing along [100] plane and the branch growing along [110] plane. Photocatalytic degradation of methyl orange (MO) in the experiment indicates that pure Cu2O NWs prepared at 150 °C have a higher photocatalytic activity (90% MO were degraded within 20 min without the presence of H2O2) compared with the samples obtained at other temperatures. In the photoelectrochemical test, pure Cu2O NWs had outstanding photoelectric response, which corresponds to the catalytic performance. The superior photocatalytic performance can be attributed to the absence of grain boundaries between the small branches and the nanowire trunk, which is conducive to the transport of photo-generated carriers, and the reduction of Cu impurities to reduce the number of recombination centers.

  5. Reduced graphene oxide-CdS nanocomposite with enhanced photocatalytic 4-Nitrophenol degradation

    Chakraborty, Koushik; Ibrahim, Sk; Das, Poulomi; Ghosh, Surajit; Pal, Tanusri

    2017-05-01

    We report the photocatalytic activity of reduced graphene oxide cadmium sulfide (RGO-CdS) composite towards the degradation of 4-Nitrophenol (4-NP) under simulated solar light illumination. The solution processable RGO-CdS composite was synthesized by one pot single step low cost solvothermal process, where the reduction of graphene oxide (GO), synthesis and attachment of CdS onto RGO sheets were done simultaneously. The structural and morphological characterization of the RGO-CdS composite and the reduction of GO was confirmed by X-ray diffractometry, TEM imaging and Fourier transform infrared spectroscopy respectively. The photocatalytic efficiency of RGO-CdS composite is 2.6 times higher in compare to controlled CdS. In RGO-CdS composite the photo induced electrons transfer from CdS nanorod to RGO sheets, which reduces the recombination probability of photo generated electron-hole in the CdS. These well separated photoinduced charges enhanced the photocatalytic activity of the RGO-CdS composite. Our study establishes the RGO-CdS composite as a potential photocatalyst for the degradation of organic water pollutant.

  6. Photocatalytic degradation of commercial phoxim over La-doped TiO2 nanoparticles in aqueous suspension.

    Dai, Ke; Peng, Tianyou; Chen, Hao; Liu, Juan; Zan, Lin

    2009-03-01

    Photocatalytic degradation of commercial phoxim emulsion in aqueous suspension was investigated by using La-doped mesoporous TiO2 nanoparticles (m-TiO2) as the photocatalyst under UV irradiation. Effects of La-doping level, calcination temperature, and additional amount of the photocatalyst on the photocatalytic degradation efficiency were investigated in detail. Experimental results indicate that 20 mg L(-1) phoxim in 0.5 g L(-1) La/m-TiO2 suspension (the initial pH 4.43) can be decomposed as prolonging the irradiation time. Almost 100% phoxim was decomposed after 4 h irradiation according to the spectrophotometric analyses, whereas the mineralization rate of phoxim just reached ca. 80% as checked by ion chromatography (IC) analyses. The elimination of the organic solvent in the phoxim emulsion as well as the formation and decomposition of some degradation intermediates were observed by high-performance liquid chromatography-mass spectroscopy (HPLC-MS). On the basis of the analysis results on the photocatalytic degradation intermediates, two possible photocatalytic degradation pathways are proposed under the present experimental conditions, which reveal that both the hydrolysis and adsorption of phoxim under UV light irradiation play important roles during the photocatalytic degradation of phoxim.

  7. Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-01-01

    Highlights: • Bi_2Se_3 and Ni doped Bi_2Se_3 were synthesized by solvothermal approach. • Presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. • Complete degradation of malachite green (MG) dye was achieved by Ni doped Bi_2Se_3 with H_2O_2. • Remarkable photo-catalytic degradation by doped bismuth selenide has been explained. • Scavenger tests show degradation of MG is mainly dominated by ·OH oxidation process. - Abstract: Bismuth selenide (Bi_2Se_3) and nickel (Ni) doped Bi_2Se_3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi_2Se_3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi_2Se_3 sample exhibited higher photo-catalytic activity than that of the pure Bi_2Se_3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi_2Se_3 in presence of hydrogen peroxide (H_2O_2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

  8. Kinetic study on the photocatalytic degradation of salicylic acid using ZnO catalyst

    Nageswara Rao, A.; Sivasankar, B.; Sadasivam, V.

    2009-01-01

    The photocatalytic degradation of salicylic acid was studied by a batch process using ZnO as the catalyst on irradiation with UV light. The effect of process parameters such as pH, catalyst loading and initial concentration of salicylic acid on the extent of degradation was investigated. The degradation of salicylic acid was found to be effective in the neutral pH range. The optimum catalyst loading was observed at 2.0 g/L. The process followed first order kinetics and the apparent rate constant decreased with increase in the initial concentration of salicylic acid. The mechanism for the degradation of salicylic acid could be explained on the basis of Langmuir-Hinshelwood mechanism. The complete mineralization of salicylic acid was observed in the presence of ZnO photocatalyst. The ZnO was found to be quite stable and undergoes photocorrosion only to a negligible extent.

  9. Melamine modified P25 with heating method and enhanced the photocatalytic activity on degradation of ciprofloxacin

    Wang, Huiqin [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Jinze; Ma, Changchang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng [School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China); Lu, Ziyang [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Huo, Pengwei, E-mail: huopw1@163.com [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Yongsheng [School of Chemistry & Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-02-28

    Highlights: • We demonstrated the as-prepared photocatalyst of g-C{sub 3}N{sub 4}-TiO{sub 2} with the commercial TiO{sub 2} (P25) composited melamine under ball milling and calcined. • The enhanced photocatalytic performance could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. • The possible photocatalytic mechanism of g-C{sub 3}N{sub 4}/P25 under visible light irradiation is proposed. - Abstract: The graphitic carbon nitride (g-C{sub 3}N{sub 4}), as one photocatalyst which possess the suitable band gap, is better for modified TiO{sub 2} and enhanced photocatalytic degradation of organic pollutants. In this work, the g-C{sub 3}N{sub 4}/TiO{sub 2} were successfully prepared via directly calcined the mixture of melamine and P25. The as-prepared g-C{sub 3}N{sub 4}/TiO{sub 2} photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and high resolution electron microscopy (HRTEM), Raman and Fourier transform-infrared spectroscopy (FT-IR). The photocatalytic performances of g-C{sub 3}N{sub 4}/TiO{sub 2} composites were investigated by degradation of ciprofloxacin. The results showed that the g-C{sub 3}N{sub 4} and P25 were successfully composited, and the bond of C–N was well formed, the calcined temperature for as-prepared photocatalysts and the ratio of melamine and P25 were important to the degradation rate of ciprofloxacin. When the mixture of melamine and P25 with 1:2, and calcined temperature at 600 °C, the degradation rate of ciprofloxacin could reach 95% in 60 min. The enhanced photocatalytic performances could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. Finally, the possible transferred processes of photoelectrons and photoholes were proposed.

  10. Combined process of electrocoagulation and photocatalytic degradation for the treatment of olive washing wastewater.

    Ates, Hasan; Dizge, Nadir; Yatmaz, H Cengiz

    2017-01-01

    In this study, an electrocoagulation reactor (ECR) and photocatalytic reactor (PCR) were tested to understand the performance of combined electrocoagulation and photocatalytic-degradation of olive washing wastewater (OWW). The effects of initial pH (6.0, 6.9, 8.0, 9.0), applied voltage (10.0, 12.5, 15.0 V), and operating time (30, 60, 90, 120 min) were investigated in the electrocoagulation reactor when aluminum electrodes were used as both anode and cathode. The pH, conductivity, color, chemical oxygen demand (COD), and phenol were measured versus time to determine the efficiency of the ECR and PCR process. It was observed that electrocoagulation as a single treatment process supplied the COD removal of 62.5%, color removal of 98.1%, and total phenol removal of 87% at optimum conditions as pH 6.9, applied voltage of 12.5 V, and operating time of 120 min. Moreover, final pH and conductivity were 7.7 and 980 μS/cm, respectively. On the other hand, the effect of semiconductor catalyst type (TiO 2 and ZnO) and loading (1, 2, 3 g/L) were tested using PCR as a stand-alone technique. It was found that photocatalytic degradation as a single treatment process when using 1 g/L ZnO achieved the COD removal of 46%, color removal of 99% with a total phenol removal of 41% at optimum conditions. Final pH and conductivity were 6.2 and 915 μS/cm, respectively. Among semiconductor catalysts, TiO 2 and ZnO performed identical efficiencies for both COD and total phenol removal. Moreover, combination in which electrochemical degradation was employed as a pre-treatment to the photocatalytic degradation process obtained high COD removal of 88% and total phenol, as well as color removal of 100% for the OWW. The electrochemical treatment alone was not effective, but in combination with the photocatalytic process, led to a high-quality effluent. Finally, sludge collected from the electrocoagulation process was characterized by attenuated total reflection Fourier transform infrared and X

  11. Efficient photocatalytic degradation of rhodamine 6G with a quantum dot-metal organic framework nanocomposite.

    Kaur, Rajnish; Vellingiri, Kowsalya; Kim, Ki-Hyun; Paul, A K; Deep, Akash

    2016-07-01

    The hybrid structures of metal organic frameworks (MOFs) and nanoparticles may offer the realization of effective photocatalytic materials due to combined benefits of the porous and molecular sieving properties of MOF matrix and the functional characteristics of encapsulated nanoparticles. In this study, cadmium telluride (CdTe) quantum dots (QD) are conjugated with a europium-MOF for the synthesis of a novel nanocomposite material with photocatalytic properties. Successful synthesis of a QD/Eu-MOF nanocomposite was characterized with various spectroscopic and microscopic techniques. This QD/Eu-MOF is found to be an effective catalyst to complete the degradation of Rhodamine 6G dye within 50 min. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Solution processable RGO-CdZnS composite for solar light responsive photocatalytic degradation of 4-Nitrophenol

    Ibrahim, Sk; Chakraborty, Koushik; Pal, Tanusri; Ghosh, Surajit

    2017-05-01

    We report the one pot single step synthesis and characterization of solution processable reduced graphene oxide (RGO) - cadmium zinc sulfide (CdZnS) nanocomposite materials. The composite was characterized structurally and morphologically by XRD and TEM studies. The reduction of GO in RGO-CdZnS composite, was confirmed by XPS and Raman spectroscopy. The photocatalytic activity of the RGO-CdZnS composite was investigated towards the degradation of 4-Nitrophenol. A notable increase of photocatalytic efficiency of RGO-CdZnS compare to controlled CdZnS was observed. Here RGO plays a crucial role to efficient photo induced charge separation from the CdZnS, and decreases the electron-hole recombination probability and subsequently enhanced the photocatalytic activity of the RGO-CdZnS composite material under simulated solar light irradiation. This work highlights the potential application of RGO-based materials in the field of photocatalytic degradation of organic water pollutant.

  13. Glycol stabilized magnetic nanoparticles for photocatalytic degradation of xylenol orange

    Ullah, Ikram; Ali, Farman; Ali, Zarshad; Humayun, Muhammad; wahab, Zain Ul

    2018-05-01

    In this work, we have successfully prepared ZnFe2O4 magnetic nanoparticles as photocatalysts via co-precipitation method using triethylene glycol as a stabilizing agent. The resultant nanoparticles were annealed at 400 °C and then acid etched and surface functionalized with 3-(triethoxysilyl) propyl amine (APTES). Fourier transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD) analysis were used to characterize these magnetic photocatalysts. XRD patterns revealed that the size of annealed and functionalized ZnFe2O4 nanoparticles falls in the range of 23.3 and 13.9 nm, respectively. The optical band gaps of the magnetic photocatalysts were calculated from UV–Visible absorption spectra using Tauc plots. The band gap of the ZnFe2O4 photocatalyst in acidic and basic medium was 2.47 and 2.7 eV, respectively. The performance of the magnetic photocatalysts was evaluated for xylenol orange (XO) degradation. The degradation rates of XO dye for the blank, annealed and functionalized photocatalysts at pH = 4 were 76%, 85%, and 90%, respectively. In addition, the influence of important parameters such as contact time, pH, catalyst, and dye dose were also investigated for all the three photocatalysts. The applied kinetics models demonstrated that the degradation followed pseudo 1st order.

  14. Solid-phase photocatalytic degradation of polyethylene film with manganese oxide OMS-2

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Cui, Jingzhen; Zhou, Wenbing

    2011-01-01

    Solid-phase photocatalytic degradation of polyethylene (PE) film with cryptomelane-type manganese oxide (OMS-2) as photocatalyst was investigated in the ambient air under ultraviolet and visible light irradiation. The properties of the composite films were compared with those of the pure PE film through performing weight loss monitoring, IR spectroscopy, scanning electron microscopic (SEM) and X-ray photoelectron spectroscopy (XPS). The photoinduced degradation of PE-OMS-2 composite films was higher than that of the pure films, while there has been little change under the visible light irradiation. The weight loss of PE-OMS-2 (1.0 wt%) composite films steadily decreased and reached 16.5% in 288 h under UV light irradiation. Through SEM observation there were some cavities on the surface of composite films, but few change except some surface chalking phenomenon occurred in pure PE film. The degradation rate with ultraviolet irradiation is controllable by adjusting the content of OMS-2 particles in PE plastic. Finally, the mechanism of photocatalytic degradation of the composite films was briefly discussed.

  15. Solar photocatalytic degradation of isoproturon over TiO{sub 2}/H-MOR composite systems

    Sharma, Mangalampalli V. Phanikrishna; Durgakumari, Valluri [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500607 (India); Subrahmanyam, Machiraju [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500607 (India)], E-mail: subrahmanyam@iict.res.in

    2008-12-30

    The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO{sub 2} over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO{sub 2}, H-MOR support and different wt% of TiO{sub 2} over the support on the photocatalytic degradation and influence of parameters such as TiO{sub 2} loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15 wt% TiO{sub 2}/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and {approx}80% mineralization occurred in 5 h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS)

  16. Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems

    Sharma, Mangalampalli V. Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

    2008-01-01

    The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO 2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO 2 , H-MOR support and different wt% of TiO 2 over the support on the photocatalytic degradation and influence of parameters such as TiO 2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15 wt% TiO 2 /H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and ∼80% mineralization occurred in 5 h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS)

  17. Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems.

    Sharma, Mangalampalli V Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

    2008-12-30

    The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO2, H-MOR support and different wt% of TiO2 over the support on the photocatalytic degradation and influence of parameters such as TiO2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15wt% TiO2/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and approximately 80% mineralization occurred in 5h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS).

  18. Photocatalytic reusable membranes for the effective degradation of tartrazine with a solar photoreactor.

    Aoudjit, L; Martins, P M; Madjene, F; Petrovykh, D Y; Lanceros-Mendez, S

    2018-02-15

    Recalcitrant dyes present in effluents constitute a major environmental concern due to their hazardous properties that may cause deleterious effects on aquatic organisms. Tartrazine is a widely-used dye, and it is known to be resistant to biological and chemical degradation processes and by its carcinogenic and mutagenic nature. This study presents the use of TiO 2 (P25) nanoparticles immobilized into a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) membrane to assess the photocatalytic degradation of this dye in a solar photoreactor. The nanocomposite morphological properties were analyzed, confirming an interconnected porous microstructure and the homogeneous distribution of the TiO 2 nanoparticles within the membrane pores. It is shown that the nanocomposite with 8wt% TiO 2 exhibits a remarkable sunlight photocatalytic activity over five hours, with 78% of the pollutant being degraded. It was also demonstrated that the degradation follows pseudo-first-order kinetics model at low initial tartrazine concentration. Finally, the effective reusability of the produced nanocomposite was also assessed. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Photocatalytic degradation of perfluorooctanoic acid with beta-Ga2O3 in anoxic aqueous solution.

    Zhao, Baoxiu; Lv, Mou; Zhou, Li

    2012-01-01

    Perfluorooctanoic acid (PFOA) is a new-found hazardous persistent organic pollutant, and it is resistant to decomposition by hydroxyl radical (HO*) due to its stable chemical structure and the high electronegativity of fluorine. Photocatalytic reduction of PFOA with beta-Ga2O3 in anoxic aqueous solution was investigated for the first time, and the results showed that the photoinduced electron (e(cb-)) coming from the beta-Ga2O3 conduction band was the major degradation substance for PFOA, and shorter-chain perfluorinated carboxylic acids (PFCAs, CnF2n+i1COOH, 1 < or = n < or = 6) were the dominant products. Furthermore, the concentration of F- was measured by the IC technique and defluorination efficiency was calculated. After 3 hr, the photocatalytic degradation efficiency was 98.8% and defluorination efficiency was 31.6% in the presence of thiosulfate and bubbling N2. The degradation reaction followed first-order kinetics (k = 0.0239 min(-1), t1/2 = 0.48 hr). PFCAs (CnF2n+1COOH, 1 < or = n < or = 7) were detected and measured by LC-MS and LC-MS/MS methods. It was deduced that the probable photocatalytic degradation mechanism involves e(cb-) attacking the carboxyl of CnF2n+1COOH, resulting in decarboxylation and the generation of CnF2n+1*. The produced CnF2n+1* reacted with H2O, forming CnF2n+1OH, then CnF2n+1OH underwent HF loss and hydrolysis to form CnF2n+1COOH.

  20. Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacin

    Salma, Alaa; Thoröe-Boveleth, Sven; Schmidt, Torsten C.; Tuerk, Jochen

    2016-01-01

    Highlights: • Identification of transformation products using an isotopically labeled surrogate. • 4 of 18 detected transformation products have been identified for the first time. • Revision of 2 molecular structures of previously reported transformation products. • PH dependence of photolytic and photocatalytic degradation of ciprofloxacin. - Abstract: Ciprofloxacin (CIP) is a broad-spectrum antibiotic with five pH dependent species in aqueous medium, which makes its degradation behavior difficult to predict. For the identification of transformation products and prediction of degradation mechanisms, a new experimental concept making use of isotopically labeled compounds together with high resolution mass spectrometry was successfully established. The utilization of deuterated ciprofloxacin (CIP-d8) facilitated the prediction of three different degradation pathways and the corresponding degradation products, four of which were identified for the first time. Moreover, two molecular structures of previously reported transformation products were revised according to the mass spectra and product ion spectra of the deuterated transformation products. Altogether, 18 transformation products have been identified during the photolytic and photocatalytic reactions at different pH values (3, 5, 7 and 9). In this work the influence of pH on both reaction kinetics and degradation mechanism was investigated for direct ultraviolet photolysis (UV-C irradiation) and photocatalysis (TiO_2/UV-C). It could be shown that the removal rates strongly depended on pH with highest removal rates at pH 9. A comparison with those at pH 3 clearly indicated that under acidic conditions ciprofloxacin cannot be easily excited by UV irradiation. We could confirm that the first reaction step for both oxidative treatment processes is mainly defluorination, followed by degradation at the piperazine ring of CIP.

  1. Dependence of transformation product formation on pH during photolytic and photocatalytic degradation of ciprofloxacin

    Salma, Alaa [Institut für Energie- und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Straße 58-60, 47229 Duisburg (Germany); Thoröe-Boveleth, Sven [University Hospital Aachen, Institute for Hygiene and Environmental Medicine, Pauwelsstraße 30, 52074 Aachen (Germany); Schmidt, Torsten C. [University Duisburg-Essen, Faculty of Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen (Germany); Centre for Water and Environmental Research (ZWU), University Duisburg-Essen, Universitätsstraße 2, 45141 Essen (Germany); Tuerk, Jochen, E-mail: tuerk@iuta.de [Institut für Energie- und Umwelttechnik e. V. (IUTA, Institute of Energy and Environmental Technology), Bliersheimer Straße 58-60, 47229 Duisburg (Germany); Centre for Water and Environmental Research (ZWU), University Duisburg-Essen, Universitätsstraße 2, 45141 Essen (Germany)

    2016-08-05

    Highlights: • Identification of transformation products using an isotopically labeled surrogate. • 4 of 18 detected transformation products have been identified for the first time. • Revision of 2 molecular structures of previously reported transformation products. • PH dependence of photolytic and photocatalytic degradation of ciprofloxacin. - Abstract: Ciprofloxacin (CIP) is a broad-spectrum antibiotic with five pH dependent species in aqueous medium, which makes its degradation behavior difficult to predict. For the identification of transformation products and prediction of degradation mechanisms, a new experimental concept making use of isotopically labeled compounds together with high resolution mass spectrometry was successfully established. The utilization of deuterated ciprofloxacin (CIP-d8) facilitated the prediction of three different degradation pathways and the corresponding degradation products, four of which were identified for the first time. Moreover, two molecular structures of previously reported transformation products were revised according to the mass spectra and product ion spectra of the deuterated transformation products. Altogether, 18 transformation products have been identified during the photolytic and photocatalytic reactions at different pH values (3, 5, 7 and 9). In this work the influence of pH on both reaction kinetics and degradation mechanism was investigated for direct ultraviolet photolysis (UV-C irradiation) and photocatalysis (TiO{sub 2}/UV-C). It could be shown that the removal rates strongly depended on pH with highest removal rates at pH 9. A comparison with those at pH 3 clearly indicated that under acidic conditions ciprofloxacin cannot be easily excited by UV irradiation. We could confirm that the first reaction step for both oxidative treatment processes is mainly defluorination, followed by degradation at the piperazine ring of CIP.

  2. Photocatalytic Degradation of Anthracene in Closed System Reactor

    Faiq F. Karam

    2014-01-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs represent a large class of persistent organic pollutants in an environment of special concern because they have carcinogenic and mutagenic activity. In this paper, we focus on and discuss the effect of different parameters, for instance, initial concentration of Anthracene, temperature, and light intensity, on the degradation rate. These parameters were adjusted at pH 6.8 in the presence of the semiconductor materials (TiO2 as photocatalysts over UV light. The main product of Anthracene photodegradation is 9,10-Anthraquinone which isidentified and compared with the standard compound by GC-MS. Our results indicate that the optimum conditions for the best rate of degradation are 25 ppm concentration of Anthracene, regulating the reaction vessel at 308.15 K and 2.5 mW/cm2 of light intensity at 175 mg/100 mL of titanium dioxide (P25.

  3. Microwave-assisted one-pot synthesis of benzothiazole and ...

    Microwave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed ...

  4. Microwave-assisted brazing of alumina ceramics for electron tube ...

    Vickers microhardness measurement indicated reliable joint performance for the microwave-assisted brazed joints during ... Alumina ceramics are used in wide range of applications due to their .... temperature were recorded by DAQSOFT software in a sep- .... Tubes: Design and Development Capabilities (MTDDC)',.

  5. Microwave-assisted extraction and antihyperlipidemic effect of total ...

    The process of microwave-assisted extraction (MAE) of total flavonoids from corn silk and the hypolipidemia in animal models were studied. Influence of solvent concentration, microwave power, extraction time and dose of solvent were investigated and then, the orthogonal experiments were performed. Animal models of ...

  6. Microwave assisted one-pot synthesis of benzothiazole and ...

    Dr.P.T.P

    1. Microwave assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents. C PRAVEEN a. , A NANDAKUMAR a. , P DHEENKUMAR b. , D MURALIDHARAN a and P T. PERUMAL a,. * a. Organic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600020,. Tamilnadu ...

  7. Microwave-assisted extraction kinetics of terpenes from caraway seeds

    Chemat, S.; Ait-Amar, H.; Lagha, A.; Esveld, D.C.

    2005-01-01

    The process conditions during the extraction of carvone and limonene from caraway seed (Carum carvi L.) with microwave-assisted extraction have been studied with respect to microwave power, radiation dose and extraction time in order to obtain the secondary metabolites selectively. Using classical

  8. Monomode microwave-assisted atom transfer radical polymerization

    Zhang, H.; Schubert, U.S.

    2004-01-01

    The first monomode microwave-assisted atom transfer radical polymerization (ATRP) is reported. The ATRP of methyl methacrylate was successfully performed with microwave heating, which was well controlled and provided almost the same results as experiments with conventional heating, demonstrating the

  9. Microwave-Assisted Synthesis of "N"-Phenylsuccinimide

    Shell, Thomas A.; Shell, Jennifer R.; Poole, Kathleen A.; Guetzloff, Thomas F.

    2011-01-01

    A microwave-assisted synthesis of "N"-phenylsuccinimide has been developed for the second-semester organic teaching laboratory. Utilizing this procedure, "N"-phenylsuccinimide can be synthesized in moderate yields (40-60%) by heating a mixture of aniline and succinic anhydride in a domestic microwave oven for four minutes. This technique reduces…

  10. Microwave-assisted Synthesis of an Important Intermediate of Benazepril

    Mistry, B; Medhane, Dipti; Mohanraj, Krishnapriya; Ghone, Sanjeevani A.

    2010-01-01

    Rapid and efficient methods for the synthesis of an important intermediate of benazepril ethyl 3-phthalimido-2,3,4,5-tetrahydro-1H-[1]benzazepin-2-one-1-acetate under the influence of microwave irradiation are described. A comparative study of conventional and microwave assisted method is briefly discussed.

  11. Microwave-assisted Synthesis of an Important Intermediate of Benazepril

    Mistry, B; Medhane, Dipti; Mohanraj, Krishnapriya; Ghone, Sanjeevani A.

    2010-01-01

    Rapid and efficient methods for the synthesis of an important intermediate of benazepril ethyl 3-phthalimido-2,3,4,5-tetrahydro-1H-[1]benzazepin-2-one-1-acetate under the influence of microwave irradiation are described. A comparative study of conventional and microwave assisted method is briefly discussed. PMID:21188052

  12. The Influence of Surface Alumina and Silica on the Photocatalytic Degradation of Organic Pollutants

    Terry A. Egerton

    2013-03-01

    Full Text Available Practical photocatalysis for degradation of organic pollutants must take into account the influence of other chemicals. Significant Al deposition on titania can occur at naturally occurring concentrations of dissolved Al. This paper reviews the author’s work on the influence of deliberately deposited hydrous oxides of aluminium on the behavior of a ~130 m2 g−1 rutile TiO2, and then compares the behavior of deposited alumina with that of deposited silica. On rutile some adsorbed nitrogen is infrared-active. Alumina and silica deposited on the rutile reduce, and ultimately eliminate, this infrared-active species. They also reduce photocatalytic oxidation of both propan-2-ol and dichloroacetate ion and the photocatalytic reduction of diphenyl picryl hydrazine. The surface oxides suppress charge transfer and may also reduce reactant adsorption. Quantitative measurement of TiO2 photogreying shows that the adsorbed inorganics also reduce photogreying, attributed to the capture of photogenerated conduction band electrons by Ti4+ to form Ti3+. The influence of adsorbed phosphate on photocatalysis is briefly considered, since phosphate reduces photocatalytic disinfection. In the context of classical colloid studies, it is concluded that inorganic species in water can significantly reduce photoactivity from the levels that measured in pure water.

  13. Double Walled Carbon Nanotube/TiO2 Nanocomposites for Photocatalytic Dye Degradation

    Alex T. Kuvarega

    2016-01-01

    Full Text Available Double walled carbon nanotube (DWCNT/N,Pd codoped TiO2 nanocomposites were prepared by a modified sol-gel method and characterised using FTIR, Raman spectroscopy, TGA, DRUV-Vis, XRD, SEM, and TEM analyses. TEM images showed unique pearl-bead-necklace structured morphologies at higher DWCNT ratios. The nanocomposite materials showed characteristic anatase TiO2 Raman bands in addition to the carbon nanotube D and G bands. Red shifts in the UV-Vis absorption edge were observed at low DWCNT percentages. The photocatalytic activity of DWCNT/N,Pd TiO2 nanocomposite was evaluated by the photocatalytic degradation of eosin yellow under simulated solar light irradiation and the 2% DWCNT/N,Pd TiO2 nanocomposite showed the highest photoactivity while the 20% DWCNT/N,Pd TiO2 hybrid was the least efficient. The photocatalytic enhancement was attributed to the synergistic effects of the supporting and electron channeling role of the DWCNTs as well as the electron trapping effects of the platinum group metal. These phenomena favour the separation of the photogenerated electron-hole pairs, reducing their recombination rate, which consequently lead to significantly enhanced photoactivity.

  14. Photocatalytic degradation of ciprofloxacin drug in water using ZnO nanoparticles

    El-Kemary, Maged, E-mail: elkemary@yahoo.co [Photo- and Nanochemistry Laboratory, Chemistry Department, Faculty of Science, Kafrelsheikh University, 33516 Kafr ElSheikh (Egypt); El-Shamy, Hany; El-Mehasseb, Ibrahim [Photo- and Nanochemistry Laboratory, Chemistry Department, Faculty of Science, Kafrelsheikh University, 33516 Kafr ElSheikh (Egypt)

    2010-12-15

    We report the synthesis of nanostructure ZnO semiconductor with {approx}2.1 nm diameter using a chemical precipitation method. The resulting nanoparticles were characterized by X-ray diffraction analysis (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties were investigated by UV-vis and fluorescence techniques. The absorption spectra exhibit a sharp absorption edge at {approx}334 nm corresponding to band gap of {approx}3.7 eV. The fluorescence spectra displayed a near-band-edge ultraviolet excitonic emission at {approx}410 nm and a green emission peak at {approx}525 nm, due to a transition of a photo-generated electron from the conduction band to a deeply trapped hole. The photocatalytic activity of the prepared ZnO nanoparticles has been investigated for the degradation of ciprofloxacin drug under UV light irradiation in aqueous solutions of different pH values. The results showed that the photocatalytic degradation process is effective at pH 7 and 10, but it is rather slow at pH 4. Higher degradation efficiency ({approx}50%) of the drug was observed at pH 10 after 60 min. Photodegradation of the drug follows a pseudo-first-order kinetics.

  15. Photocatalytic Degradation of Safranine by ZnO-Bentonite: Photodegradation versus Adsorbability

    Sonawane, Gunvant H.; Patil, Sandip P.; Shrivastava, V. S.

    2017-06-01

    ZnO-bentonite nanocomposite was obtained by incorporation of bentonite clay with ZnO. The effects of pH, contact time, initial dye concentration and photocatalyst dose on the rate of degradation of dye solution were studied. It was observed that working conditions strongly influence the dye removal process. Contact time 70 min and pH 4 was optimized for photocatalytic degradation of Safranine. Adsorption kinetics for 20-80 mg/l dye concentration was found to follow pseudo-second-order kinetics. Adsorption of dye was described by Langmuir and Freundlich isotherm. In adsorption isotherm, Langmuir isotherm was found to fit well with experimental data than Freundlich isotherm. The monolayer adsorption capacity was found to be 50 mg/g. The amount of dye adsorbed ( q t ) increases from 17.31 to 159.62 mg/g as dye concentration increases from 20 to 80 mg/l for 0.4 g/l photocatalyst dose. The photocatalytic degradation of Safranine by ZnO-bentonite takes place by advanced oxidation process.

  16. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

    Hao Xiaolong [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Zhou Ming Hua [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Lei Lecheng [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China)]. E-mail: lclei@zju.edu.cn

    2007-03-22

    TiO{sub 2} photocatalyst (P-25) (50 mg L{sup -1}) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO{sub 2} were obviously increased. Pulsed high-voltage discharge process with TiO{sub 2} had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10{sup -6} to 1.50 x 10{sup -6} M s{sup -1}, the ozone formation rate from 1.99 x 10{sup -8} to 2.35 x 10{sup -8} M s{sup -1}, respectively. In addition, this process had no influence on the photocatalytic properties of TiO{sub 2}. The introduction of TiO{sub 2} photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

  17. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water.

    Hao, Xiao Long; Zhou, Ming Hua; Lei, Le Cheng

    2007-03-22

    TiO(2) photocatalyst (P-25) (50mgL(-1)) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO(2) were obviously increased. Pulsed high-voltage discharge process with TiO(2) had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10x10(-6) to 1.50x10(-6)Ms(-1), the ozone formation rate from 1.99x10(-8) to 2.35x10(-8)Ms(-1), respectively. In addition, this process had no influence on the photocatalytic properties of TiO(2). The introduction of TiO(2) photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

  18. Photocatalytic Active Coatings for Lignin Degradation in a Continuous Packed Bed Reactor

    Colin Awungacha Lekelefac

    2014-01-01

    Full Text Available The synthesis of immobilized catalyst on porous glass support material via the sol-gel route is reported. TiO2-P25-SiO2 + Pt, TiO2-P25-SiO2, TiOSO4_30.6 wt%, and ZnO + TiO2-P25-SiO2 catalysts were synthesized and a comparative study is done regarding morphology of coatings, degradation rates, reaction rates, dissolved carbon (DC, formation of peaks, and fluorescence of products formed from the photocatalytic degradation of lignin sulfonate obtained from a local paper plant. Through simultaneous reaction-extraction pathways applying dialysis filtration and highly porous polystyrene divinylbenzene adsorbent resin (HR-P for solid phase extraction (SPE, an attempt has been made to isolate smaller molecules produced from photocatalytic degradation. Moreover relatively high lignin sulfonate (0.5 g/L concentrations are used in the reactions. UV-Vis spectroscopy revealed a faster reduction in the concentration values for the aliphatic moiety compared to the aromatic moiety. Peaks were observed by both fluorescence spectroscopy and HPLC suggesting the production of new substances and fluorophores.

  19. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

    Hao Xiaolong; Zhou Ming Hua; Lei Lecheng

    2007-01-01

    TiO 2 photocatalyst (P-25) (50 mg L -1 ) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO 2 were obviously increased. Pulsed high-voltage discharge process with TiO 2 had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10 -6 to 1.50 x 10 -6 M s -1 , the ozone formation rate from 1.99 x 10 -8 to 2.35 x 10 -8 M s -1 , respectively. In addition, this process had no influence on the photocatalytic properties of TiO 2 . The introduction of TiO 2 photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants

  20. Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

    Kanjwal, Muzafar Ahmad; Barakat, Nasser A.M.; Chronakis, Ioannis S.

    2015-01-01

    Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver-titanium dioxide nanofibers (AgTiO2 NFs) and silver-titanium dioxide nanoparticles (AgTiO2 NPs) were individually...... incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth...

  1. Effect of W doping level on TiO2 on the photocatalytic degradation of Diuron.

    Foura, Ghania; Soualah, Ahcène; Robert, Didier

    2017-01-01

    In the present study, three compositions of W-doped titania nano-photocatalyst are synthesized via the sol-gel method. The powders obtained were characterized by X-ray diffraction, Raman spectroscopy and UV-visible diffuse reflectance spectroscopy. The photocatalytic performances of the different photocatalysts are tested with respect to the degradation of Diuron in water solutions under simulated solar light and visible light irradiation. The W 0.03 Ti 0.97 O 2 catalyst exhibits better photoactivity than the pure TiO 2 even under simulated solar light and visible light. This improvement in activity was attributed to photoelectron/hole separation efficiency.

  2. Photocatalytic Degradation Effect of μ-Dielectric Barrier Discharge Plasma Treated Titanium Dioxide Nanoparticles on Environmental Contaminant.

    Seo, Hyeon Jin; Hwang, Ki-Hwan; Na, Young Hoon; Boo, Jin-Hyo

    2018-09-01

    This study focused on the photocatalytic degradation effect of the μ-dielectric barrier discharge (μ-DBD) plasma treated titanium dioxide (TiO2) nanoparticles on environmental contaminant such as formaldehyde. TiO2 nanoparticles were treated by a μ-DBD plasma source with nitrogen gas. We analyzed the degradation of formaldehyde with the plasma treated TiO2 nanoparticles by UV-visible spectrophotometer (UV-VIS), and demonstrated that the photocatalytic activity of the μ-DBD plasma-treated TiO2 nanoparticles showed significantly high catalytic efficiency rather than without plasma treated TiO2 nanoparticles. Field emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle analyzer were used to measure the effects of photocatalytic degradation for the plasma treated TiO2 nanoparticles.

  3. Synthesis, Characterization, and Evaluation of Boron-Doped Iron Oxides for the Photocatalytic Degradation of Atrazine under Visible Light

    Shan Hu

    2012-01-01

    Full Text Available Photocatalytic degradation of atrazine by boron-doped iron oxides under visible light irradiation was investigated. In this work, boron-doped goethite and hematite were successfully prepared by sol-gel method with trimethylborate as boron precursor. The powders were characterized by XRD, UV-vis diffuse reflectance spectra, and porosimetry analysis. The results showed that boron doping could influence the crystal structure, enlarge the BET surface area, improve light absorption ability, and narrow their band-gap energy. The photocatalytic activity of B-doped iron oxides was evaluated in the degradation of atrazine under the visible light irradiation, and B-doped iron oxides showed higher atrazine degradation rate than that of pristine iron oxides. Particularly, B-doped goethite exhibited better photocatalytic activity than B-doped hematite.

  4. Photochemical removal of aniline in aqueous solutions: switching from photocatalytic degradation to photo-enhanced polymerization recovery.

    Tang, Heqing; Li, Jing; Bie, Yeqiang; Zhu, Lihua; Zou, Jing

    2010-03-15

    Organic pollutants may be treated by either a degradation process or a recovery process in the view point of sustainable chemistry. Photocatalytic removal of aniline was investigated in aqueous solutions. It was found that the photocatalytic oxidation of aniline resulted in its degradation or polymerization, depending on its concentration. Hence a new treatment strategy was proposed in combination of photocatalytic degradation and polymerization, where the polymerization was in fact a recovery process. When aniline concentration was as low as 0.1 mmol L(-1), it was possible to photocatalytically degrade aniline, which could be further enhanced by increasing solution pH, modifying TiO(2) surface with the addition of anions, or coupling with the photoreduction of added oxidants. When aniline concentration was increased to about 1 mmol L(-1), the photocatalytic oxidation was observed to yield the polymerization of aniline, leading to nanocomposites of polyaniline (PAN) and TiO(2). Alternatively, the photo-enhanced chemical polymerization of aniline at higher concentrations (>or=50 mmol L(-1)) in the presence of chemical oxidants produced PAN nanostructures. The conversion of pollutant aniline to valuable PAN nanostructures or nano-PAN/TiO(2) composites is suggestive for possible applications in the treatment of aniline wastewaters as a sustainable environmental protection measure. (c) 2009 Elsevier B.V. All rights reserved.

  5. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    Chai, Bo, E-mail: willycb@163.com; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Highlights: • The phosphorus doped g-C{sub 3}N{sub 4} photocatalysts are synthesized by a co-pyrolysis procedure. • The crystal phase, morphology, and optical property of P doped g-C{sub 3}N{sub 4} are characterized. • The P doped g-C{sub 3}N{sub 4} photocatalysts show the improved photocatalytic activity. • The possible mechanism for enhanced photocatalytic activity is proposed. - Abstract: Phosphorus doped graphitic carbon nitride (g-C{sub 3}N{sub 4}) was easily synthesized using ammonium hexafluorophosphate (NH{sub 4}PF{sub 6}) as phosphorus source, and ammonium thiocyanate (NH{sub 4}SCN) as g-C{sub 3}N{sub 4} precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C{sub 3}N{sub 4} was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV–vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C{sub 3}N{sub 4} samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C{sub 3}N{sub 4} had a superior photocatalytic activity than that of pristine g-C{sub 3}N{sub 4}, attributing to the phosphorus atoms substituting carbon atoms of g-C{sub 3}N{sub 4} frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C{sub 3}N{sub 4}. Moreover, the tests of radical scavengers demonstrated that the holes (h{sup +}) and superoxide radicals (·O{sub 2}{sup −}) were the main active species for the

  6. Photocatalytic degradation of metoprolol tartrate in suspensions of two TiO2-based photocatalysts with different surface area. Identification of intermediates and proposal of degradation pathways

    Abramović, Biljana; Kler, Sanja; Šojić, Daniela; Laušević, Mila; Radović, Tanja; Vione, Davide

    2011-01-01

    Highlights: ► Kinetics and efficiency of photocatalytic degradation of the β 1 -blocker metoprolol tartrate (MET). ► Two TiO 2 specimens employed. ► Faster degradation of MET, but slower mineralization, obtained with the TiO 2 specimen having lower surface area. ► Photocatalytic transformation pathways of MET including mineralization. - Abstract: This study investigates the efficiency of the photocatalytic degradation of metoprolol tartrate (MET), a widely used β 1 -blocker, in TiO 2 suspensions of Wackherr's “Oxyde de titane standard” and Degussa P25. The study encompasses transformation kinetics and efficiency, identification of intermediates and reaction pathways. In the investigated range of initial concentrations (0.01–0.1 mM), the photocatalytic degradation of MET in the first stage of the reaction followed approximately a pseudo-first order kinetics. The TiO 2 Wackherr induced a significantly faster MET degradation compared to TiO 2 Degussa P25 when relatively high substrate concentrations were used. By examining the effect of ethanol as a scavenger of hydroxyl radicals (·OH), it was shown that the reaction with ·OH played the main role in the photocatalytic degradation of MET. After 240 min of irradiation the reaction intermediates were almost completely mineralized to CO 2 and H 2 O, while the nitrogen was predominantly present as NH 4 + . Reaction intermediates were studied in detail and a number of them were identified using LC–MS/MS (ESI+), which allowed the proposal of a tentative pathway for the photocatalytic transformation of MET as a function of the TiO 2 specimen.

  7. Photocatalytic degradation of metoprolol tartrate in suspensions of two TiO{sub 2}-based photocatalysts with different surface area. Identification of intermediates and proposal of degradation pathways

    Abramovic, Biljana, E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Kler, Sanja, E-mail: sanja.kler@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Sojic, Daniela, E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Lausevic, Mila, E-mail: milal@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Radovic, Tanja, E-mail: tradovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Vione, Davide, E-mail: davide.vione@unito.it [Dipartimento di Chimica Analitica, Universita di Torino, Via Pietro Giuria 5, 10125 Torino (Italy)

    2011-12-30

    Highlights: Black-Right-Pointing-Pointer Kinetics and efficiency of photocatalytic degradation of the {beta}{sub 1}-blocker metoprolol tartrate (MET). Black-Right-Pointing-Pointer Two TiO{sub 2} specimens employed. Black-Right-Pointing-Pointer Faster degradation of MET, but slower mineralization, obtained with the TiO{sub 2} specimen having lower surface area. Black-Right-Pointing-Pointer Photocatalytic transformation pathways of MET including mineralization. - Abstract: This study investigates the efficiency of the photocatalytic degradation of metoprolol tartrate (MET), a widely used {beta}{sub 1}-blocker, in TiO{sub 2} suspensions of Wackherr's 'Oxyde de titane standard' and Degussa P25. The study encompasses transformation kinetics and efficiency, identification of intermediates and reaction pathways. In the investigated range of initial concentrations (0.01-0.1 mM), the photocatalytic degradation of MET in the first stage of the reaction followed approximately a pseudo-first order kinetics. The TiO{sub 2} Wackherr induced a significantly faster MET degradation compared to TiO{sub 2} Degussa P25 when relatively high substrate concentrations were used. By examining the effect of ethanol as a scavenger of hydroxyl radicals ({center_dot}OH), it was shown that the reaction with {center_dot}OH played the main role in the photocatalytic degradation of MET. After 240 min of irradiation the reaction intermediates were almost completely mineralized to CO{sub 2} and H{sub 2}O, while the nitrogen was predominantly present as NH{sub 4}{sup +}. Reaction intermediates were studied in detail and a number of them were identified using LC-MS/MS (ESI+), which allowed the proposal of a tentative pathway for the photocatalytic transformation of MET as a function of the TiO{sub 2} specimen.

  8. Role of dissolved oxygen on the degradation mechanism of Reactive Green 19 and electricity generation in photocatalytic fuel cell.

    Lee, Sin-Li; Ho, Li-Ngee; Ong, Soon-An; Wong, Yee-Shian; Voon, Chun-Hong; Khalik, Wan Fadhilah; Yusoff, Nik Athirah; Nordin, Noradiba

    2018-03-01

    In this study, a membraneless photocatalytic fuel cell with zinc oxide loaded carbon photoanode and platinum loaded carbon cathode was constructed to investigate the impact of dissolved oxygen on the mechanism of dye degradation and electricity generation of photocatalytic fuel cell. The photocatalytic fuel cell with high and low aeration rate, no aeration and nitrogen purged were investigated, respectively. The degradation rate of diazo dye Reactive Green 19 and the electricity generation was enhanced in photocatalytic fuel cell with higher dissolved oxygen concentration. However, the photocatalytic fuel cell was still able to perform 37% of decolorization in a slow rate (k = 0.033 h -1 ) under extremely low dissolved oxygen concentration (approximately 0.2 mg L -1 ) when nitrogen gas was introduced into the fuel cell throughout the 8 h. However, the change of the UV-Vis spectrum indicates that the intermediates of the dye could not be mineralized under insufficient dissolved oxygen level. In the aspect of electricity generation, the maximum short circuit current (0.0041 mA cm -2 ) and power density (0.00028 mW cm -2 ) of the air purged photocatalytic fuel cell was obviously higher than that with nitrogen purging (0.0015 mA cm -2 and 0.00008 mW cm -2 ). Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A complete degradation of organophosphates by microwave-assisted hydrolysis

    Jansa, Petr; Čechová, Lucie; Janeba, Zlatko

    2016-01-01

    Roč. 3, č. 3 (2016), s. 219-226 ISSN 2213-3356 R&D Projects: GA MV VG20102015046 Institutional support: RVO:61388963 Keywords : organophosphates * microwave irradiation * hydrolysis Subject RIV: CC - Organic Chemistry

  10. Photocatalytic degradation of methyl orange with W-doped TiO2 synthesized by a hydrothermal method

    Tian Hua; Ma Junfeng; Li Kang; Li Jinjun

    2008-01-01

    Nanosized W-doped TiO 2 photocatalysts were synthesized by a simple hydrothermal method, and characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area analyzer. The photocatalytic activity of undoped TiO 2 and W-doped TiO 2 photocatalysts was evaluated by the photocatalytic oxidation degradation of methyl orange in aqueous solution. The results show that the photocatalytic activity of the W-doped TiO 2 photocatalyst is much higher than that of undoped TiO 2 , and the optimum percentage of W doped is 2.0 mol%. The enhanced photocatalytic activity of the doped photocatalyst may be attributed to the increase in the charge separation efficiency and the presence of surface acidity

  11. Photocatalytic degradation of trichloroethylene in aqueous phase using nano-ZNO/Laponite composites

    Joo, Jin Chul; Ahn, Chang Hyuk; Jang, Dae Gyu; Yoon, Young Han; Kim, Jong Kyu; Campos, Luiza; Ahn, Hosang

    2013-01-01

    Highlights: • Stable nano-ZnO/Laponite composites (NZLc) as an alternative to TiO 2 were produced. • Nanoscale ZnO complexed with NZLc was found to be an effective photocatalyst. • TCE removal efficiency of NZLc was greater than that of bare nanoscale ZnO. • Nanoscale ZnO-mediated photodegradation varied with experimental conditions. • Developed NZLc overcame drawbacks (e.g., filtration and recovery of photocatalysts). -- Abstract: The feasibility of nano-ZnO/Laponite composites (NZLc) as a valid alternative to TiO 2 to mineralize trichloroethylene (TCE) without difficulties for recovery of photocatalysts was evaluated. Based on the experimental observations, the removal of TCE using NZLc under UV irradiation was multiple reaction processes (i.e., sorption, photolysis, and photocatalysis). Sorption of TCE was thermodynamically favorable due to the hydrophobic partitioning into crosslinked poly vinyl alcohol, and the adsorption onto high-surface-area mineral surfaces of both ZnO and Laponite. The degradation efficiency of TCE can be significantly improved using NZLc under UV irradiation, indicating that ZnO-mediated heterogeneous photocatalytic degradation occurred. However, the degradation efficiency was found to vary with experimental conditions (e.g., initial concentration of TCE, loading amount of NZLc, the intensity of light and initial solution pH). Although the removal of TCE by NZLc was found to be a complex function of sorption, photolysis, and photocatalysis, the photocatalytic degradation of TCE on the surface of ZnO was critical. Consequently, developed NZLc can be applied as a valid alternative to suspended TiO 2 powder, and overcome drawbacks (e.g., filtration and recovery of photocatalysts) in degradation of TCE for various water resources

  12. Enhanced photocatalytic degradation of dyes under sunlight using biocompatible TiO2 nanoparticles

    Bharati, B.; Sonkar, A. K.; Singh, N.; Dash, D.; Rath, Chandana

    2017-08-01

    As TiO2 is one of the most popular photocatalysts, we have studied here the photocatalytic degradation of the most common dyestuffs like rhodamine B (RhB), congo red (CR) and methylene blue (MB), which mainly come from the textile and photographic industries using nanoparticles of TiO2. Nanoparticles of TiO2 synthesized through a simple and cost effective sol-gel technique crystallizes in the anatase phase, showing a band gap less than that of bulk value. Particles consisting of coherently scattered domains of size 33 nm are found to be agglomerated and polycrystalline in nature. While the degradation rates of MB, CR and RhB after irradiating with a renewable source of energy, i.e. sunlight, show 100% degradation, TiO2 irradiated with UV light of 4.8 eV shows a much slower degradation rate. To use the waste water after photocatalysis, we examine further the biocompatibile nature of the TiO2 nanoparticles by platelet interaction activity, hemolysis effect and MTT assay. It is worth mentioning here that TiO2 nanoparticles are found to be highly hemocompatible, show no platelet aggregation, and the level of intracellular ROS in human platelets does not show significant change in ROS level. We conclude that TiO2 nanoparticles constitute an excellent photocatalyst and biocompatible material, and that after photocatalytic degradation of dye effluents obtained from textile industries, purified water can be used in agriculture and domestic sectors.

  13. Photocatalytic degradation of trichloroethylene in aqueous phase using nano-ZNO/Laponite composites

    Joo, Jin Chul; Ahn, Chang Hyuk; Jang, Dae Gyu; Yoon, Young Han [Korea Institute of Construction Technology, Water Resource and Environment Research Department (Korea, Republic of); Kim, Jong Kyu; Campos, Luiza [University College London, Department of Civil, Environmental, and Geomatic Engineering (United Kingdom); Ahn, Hosang, E-mail: hahn@kict.re.kr [Korea Institute of Construction Technology, Water Resource and Environment Research Department (Korea, Republic of)

    2013-12-15

    Highlights: • Stable nano-ZnO/Laponite composites (NZLc) as an alternative to TiO{sub 2} were produced. • Nanoscale ZnO complexed with NZLc was found to be an effective photocatalyst. • TCE removal efficiency of NZLc was greater than that of bare nanoscale ZnO. • Nanoscale ZnO-mediated photodegradation varied with experimental conditions. • Developed NZLc overcame drawbacks (e.g., filtration and recovery of photocatalysts). -- Abstract: The feasibility of nano-ZnO/Laponite composites (NZLc) as a valid alternative to TiO{sub 2} to mineralize trichloroethylene (TCE) without difficulties for recovery of photocatalysts was evaluated. Based on the experimental observations, the removal of TCE using NZLc under UV irradiation was multiple reaction processes (i.e., sorption, photolysis, and photocatalysis). Sorption of TCE was thermodynamically favorable due to the hydrophobic partitioning into crosslinked poly vinyl alcohol, and the adsorption onto high-surface-area mineral surfaces of both ZnO and Laponite. The degradation efficiency of TCE can be significantly improved using NZLc under UV irradiation, indicating that ZnO-mediated heterogeneous photocatalytic degradation occurred. However, the degradation efficiency was found to vary with experimental conditions (e.g., initial concentration of TCE, loading amount of NZLc, the intensity of light and initial solution pH). Although the removal of TCE by NZLc was found to be a complex function of sorption, photolysis, and photocatalysis, the photocatalytic degradation of TCE on the surface of ZnO was critical. Consequently, developed NZLc can be applied as a valid alternative to suspended TiO{sub 2} powder, and overcome drawbacks (e.g., filtration and recovery of photocatalysts) in degradation of TCE for various water resources.

  14. Removal of MCs by Bi2O2CO3: adsorption and the potential of photocatalytic degradation.

    Wang, Yujiao; Cao, Yanqiu; Li, Hongmei; Gong, Aijun; Han, Jintao; Qian, Zhen; Chao, Wenran

    2018-04-01

    Microcystins (MCs) is a kind of hepatotoxin, which is the secondary metabolite of cyanobacteria. Bi 2 O 2 CO 3 (BOC) is a kind of cheap and nontoxic semiconductor material. BOC was synthetized by solvothermal method and then microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were removed by BOC, through adsorption and photocatalytic degradation. When the dosage of BOC is 6 g/L, the MC-LR and MC-RR in the natural water sample can be completely adsorbed in 30 min and then after 12 h irradiation, MC-LR and MC-RR were photocatalytically degraded by BOC.

  15. Characterization of intermediate products of solar photocatalytic degradation of ranitidine at pilot-scale.

    Radjenović, Jelena; Sirtori, Carla; Petrović, Mira; Barceló, Damià; Malato, Sixto

    2010-04-01

    In the present study the mechanisms of solar photodegradation of H(2)-receptor antagonist ranitidine (RNTD) were studied in a well-defined system of a pilot plant scale Compound Parabolic Collector (CPC) reactor. Two types of heterogeneous photocatalytic experiments were performed: catalysed by titanium-dioxide (TiO(2)) semiconductor and by Fenton reagent (Fe(2+)/H(2)O(2)), each one with distilled water and synthetic wastewater effluent matrix. Complete disappearance of the parent compounds and discreet mineralization were attained in all experiments. Furthermore, kinetic parameters, main intermediate products, release of heteroatoms and formation of carboxylic acids are discussed. The main intermediate products of photocatalytic degradation of RNTD have been structurally elucidated by tandem mass spectrometry (MS(2)) experiments performed at quadrupole-time of flight (QqToF) mass analyzer coupled to ultra-performance liquid chromatograph (UPLC). RNTD displayed high reactivity towards OH radicals, although a product of conduction band electrons reduction was also present in the experiment with TiO(2). In the absence of standards, quantification of intermediates was not possible and only qualitative profiles of their evolution could be determined. The proposed TiO(2) and photo-Fenton degradation routes of RNTD are reported for the first time. (c) 2010 Elsevier Ltd. All rights reserved.

  16. Continuous-Flow Photocatalytic Degradation of Organics Using Modified TiO2 Nanocomposites

    Imran Ali

    2018-01-01

    Full Text Available In this study, TiO2 nanotubes (TNTs were fabricated on a Ti sheet following the anodic oxidation method and were decorated with reduced graphene oxide (RGO, graphene oxide (GO, and bismuth (Bi via electrodeposition. The surface morphologies, crystal structures, and compositions of the catalyst were characterized by field emission scanning electron microscopy, Auger electron spectroscopy, X-ray diffraction, photoluminance spectra, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The TNTs loaded with RGO, GO, and Bi were used in a continuous-flow system as photocatalysts for the degradation of methylene blue (MB dye. It was found that the TNTs are efficient photocatalysts for the removal of color from water; upon UV irradiation on TNTs, the MB removal ratio was ~89%. Moreover, the photocatalytic activities of the decorated TNTs were higher than that of pristine TNTs in visible light. In comparison with TNTs, the rate of MB removal in visible light was increased by a factor of 3.4, 3.2, and 2.9 using RGO-TNTs, Bi-TNTs, and GO-TNTs, respectively. The reusability of the catalysts were investigated, and their quantum efficiencies were also calculated. The cylindrical anodized TNTs were excellent photocatalysts for the degradation of organic pollutants. Thus, it was concluded that the continuous-flow photocatalytic reactor comprising TNTs and modified TNTs is suitable for treating wastewater in textile industries.

  17. Fluorescence quenching and photocatalytic degradation of textile dyeing waste water by silver nanoparticles

    Kavitha, S. R.; Umadevi, M.; Janani, S. R.; Balakrishnan, T.; Ramanibai, R.

    2014-06-01

    Silver nanoparticles (Ag NPs) of different sizes have been prepared by chemical reduction method and characterized using UV-vis spectroscopy and transmission electron microscopy (HRTEM). Fluorescence spectral analysis showed that the quenching of fluorescence of textile dyeing waste water (TDW) has been found to decrease with decrease in the size of the Ag NPs. Experimental results show that the silver nanoparticles can quench the fluorescence emission of adsorbed TDW effectively. The fluorescence interaction between Ag NPs (acceptor) and TDW (donor) confirms the Förster Resonance Energy Transfer (FRET) mechanism. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer. Furthermore, photocatalytic degradation of TDW was measured spectrophotometrically by using silver as nanocatalyst under UV light illumination. The kinetic study revealed that synthesized Ag NPs was found to be effective in degrading TDW.

  18. Structural insights into photocatalytic performance of carbon nitrides for degradation of organic pollutants

    Oh, Junghoon; Shim, Yeonjun; Lee, Soomin; Park, Sunghee; Jang, Dawoon; Shin, Yunseok; Ohn, Saerom; Kim, Jeongho; Park, Sungjin

    2018-02-01

    Degradation of organic pollutants has a large environmental impact, with graphitic carbon nitride (g-C3N4) being a promising metal-free, low cost, and environment-friendly photocatalyst well suited for this purpose. Herein, we investigate the photocatalytic performance of g-C3N4-based materials and correlate it with their structural properties, using three different precursors (dicyandiamide, melamine, and urea) and two heating processes (direct heating at 550 °C and sequential heating at 300 and 550 °C) to produce the above photocatalysts. We further demonstrate that sequential heating produces photocatalysts with grain sizes and activities larger than those of the catalysts produced by direct heating and that the use of urea as a precursor affords photocatalysts with larger surface areas, allowing efficient rhodamine B degradation under visible light.

  19. Photocatalytic degradation of organic dyes using composite nanofibers under UV irradiation

    Salama, Ahmed; Mohamed, Alaa; Aboamera, Nada M.; Osman, T. A.; Khattab, A.

    2018-02-01

    In this work, photocatalytic degradation of organic dyes such as methylene blue (MB) and indigo carmine (IC) have been studied by composite nanofibers systems containing cellulose acetate (CA), multiwall carbon nanotubes (CNT) and TiO2 nanoparticles under UV light. The amino factionalized TiO2-NH2 NPs cross-linked to the CA/CNT composite nanofibers works as a semiconductor catalyst. The morphology and crystallinity were characterized by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy. It was also seen that many factors affected the photodegradation rate, mainly the pH of the solution and the dye concentration, temperature, etc. The study demonstrated that IC degrades at a higher rate than MB. The maximum photodegradation rate of both organic dyes was achieved at a pH 2. In comparison to other studies, this work achieved high photodegradation rate in lower time and using less power intensity.

  20. Photocatalytic degradation kinetics, mechanism and ecotoxicity assessment of tramadol metabolites in aqueous TiO{sub 2} suspensions

    Antonopoulou, U. [Department of Environmental and Natural Resources Management, University of Patras, 30100 Agrinio (Greece); Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece); Hela, D. [Department of Business Administration of Food and Agricultural Products, University of Patras, Agrinio 30100 (Greece); Konstantinou, I., E-mail: iokonst@cc.uoi.gr [Department of Environmental and Natural Resources Management, University of Patras, 30100 Agrinio (Greece); Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)

    2016-03-01

    This study investigated for the first time the photocatalytic degradation of three well-known transformation products (TPs) of pharmaceutical Tramadol, N-desmethyl-(N-DES), N,N-bidesmethyl (N,N-Bi-DES) and N-oxide-tramadol (N-OX-TRA) in two different aquatic matrices, ultrapure water and secondary treated wastewater, with high (10 mg L{sup −1}) and low (50 μg L{sup −1}) initial concentrations, respectively. Total disappearance of the parent compounds was attained in all experiments. For initial concentration of 10 mg L{sup −1}, the target compounds were degraded within 30–40 min and a mineralization degree of more than 80% was achieved after 240 min of irradiation, while the contained organic nitrogen was released mainly as NH{sub 4}{sup +} for N-DES, N,N-Bi-DES and NO{sub 3}{sup −} for N-OX-TRA. The degradation rates of all the studied compounds were considerably decreased in the wastewater due to the presence of inorganic and organic constituents typically found in effluents and environmental matrices which may act as scavengers of the HO{sup •}. The effect of pH (4, 6.7, 10) in the degradation rates was studied and for N-DES-TRA and N,N-Bi-DES-TRA, the optimum pH value was 6.7. In contrast, N-OX-TRA showed an increasing trend in the photocatalytic degradation kinetic in alkaline solutions (pH 10). The major transformation products were identified by high resolution accurate mass spectrometry coupled with liquid chromatography (HR-LC–MS). Scavenging experiments indicated for all studied compounds the important role of HO{sup •} in the photocatalytic degradation pathways that included mainly hydroxylation and further oxidation of the parent compounds. In addition, Microtox bioassay (Vibrio fischeri) was employed for evaluating the ecotoxicity of photocatalytically treated solutions. Results clearly demonstrate the progressive decrease of the toxicity and the efficiency of the photocatalytic process in the detoxification of the irradiated solutions

  1. Photocatalytic degradation of TCE in water using TiO{sub 2} catalyst

    Farooq, Muhammad [Pakistan National Accreditation Council, 4th Floor Evacuee Trust Complex, F-5/1 Islamabad (Pakistan); Raja, Iftikhar A.; Pervez, Arshad [Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad (Pakistan)

    2009-09-15

    Wastewater is generally released untreated into the rivers and streams in developing countries. Industrial wastewater usually contains highly toxic pollutants, cyanides, chlorinated compounds such as trichloroethylene (TCE). Ultraviolet (UV) radiation from sunlight also decomposes organic compounds by oxidation process. However, the process is less effective due to large amount of toxic effluent entering the main stream water. The solar radiation can effectively be applied to accelerate the process by using suitable catalyst for economically cleaning the major fresh water sources. This paper describes photocatalytic degradation of trichloroethylene in aqueous solution using TiO{sub 2}. Variable parameters such as initial concentration of TCE, type and concentration of TiO{sub 2} and reaction time are investigated. The powder TiO{sub 2} is found more effective than the sand TiO{sub 2} for decomposing TCE. The effect of sand TiO{sub 2} as photocatalyst is investigated at various water depths. It is observed that up to 45 mm water depth, sand TiO{sub 2} shows photo-degradation of TCE. The degradation rate increases as the concentration of TCE is increased up to 45 {mu}l of TCE per litre of water. Similarly the photocatalytic degradation increases with TiO{sub 2} concentration up to 0.7 g L{sup -1} of solution but then starts decreasing. The optimum values of TiO{sub 2} and TCE concentration obtained are 0.7 g and 35 {mu}l L{sup -1} of the solution, respectively. (author)

  2. Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water

    Mohamed, Alaa [Department of Materials and NanoPhysics, Royal Institute of Technology (KTH), 16440 Kista, Stockholm (Sweden); Mechanical Design and Production Engineering Department, Cairo University, 12613 Giza (Egypt); Production Engineering and Printing Technology Department, Akhbar El Yom Academy, 12655 Giza (Egypt); El-Sayed, Ramy [Experimental Cancer Medicine, KFC, Novum, Department of laboratory Medicine, Karolinska Institute, 14186 Stockholm (Sweden); Osman, T.A. [Mechanical Design and Production Engineering Department, Cairo University, 12613 Giza (Egypt); Toprak, M.S.; Muhammed, M. [Department of Materials and NanoPhysics, Royal Institute of Technology (KTH), 16440 Kista, Stockholm (Sweden); Uheida, A., E-mail: salam@kth.se [Department of Materials and NanoPhysics, Royal Institute of Technology (KTH), 16440 Kista, Stockholm (Sweden)

    2016-02-15

    In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO{sub 2} nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity compared to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles. - Highlights: • Develop effective photocatalyst based on PAN–CNT/TiO{sub 2}–NH{sub 2} composite nanofibers. • High photodegradation efficiency and fast kinetics was obtained. • Regeneration of the composite nanofibers allowed the reuse of these material. • Mechanism of the photocatalytic degradation was proposed. • The flexibility of the composite nanofibers allows use in a continuous operation mode.

  3. Composite nanofibers for highly efficient photocatalytic degradation of organic dyes from contaminated water

    Mohamed, Alaa; El-Sayed, Ramy; Osman, T.A.; Toprak, M.S.; Muhammed, M.; Uheida, A.

    2016-01-01

    In this study highly efficient photocatalyst based on composite nanofibers containing polyacrylonitrile (PAN), carbon nanotubes (CNT), and surface functionalized TiO 2 nanoparticles was developed. The composite nanofibers were fabricated using electrospinning technique followed by chemical crosslinking. The surface modification and morphology changes of the fabricated composite nanofibers were examined through SEM, TEM, and FTIR analysis. The photocatalytic performance of the composite nanofibers for the degradation of model molecules, methylene blue and indigo carmine, under UV irradiation in aqueous solutions was investigated. The results demonstrated that high photodegradation efficiency was obtained in a short time and at low power intensity compared to other reported studies. The effective factors on the degradation of the dyes, such as the amount of catalyst, solution pH and irradiation time were investigated. The experimental kinetic data were fitted using pseudo-first order model. The effect of the composite nanofibers as individual components on the degradation efficiency of MB and IC was evaluated in order to understand the overall photodegradation mechanism. The results obtained showed that all the components possess significant effect on the photodegradation activity of the composite nanofibers. The stability studies demonstrated that the photodegradation efficiency can remain constant at the level of 99% after five consecutive cycles. - Highlights: • Develop effective photocatalyst based on PAN–CNT/TiO 2 –NH 2 composite nanofibers. • High photodegradation efficiency and fast kinetics was obtained. • Regeneration of the composite nanofibers allowed the reuse of these material. • Mechanism of the photocatalytic degradation was proposed. • The flexibility of the composite nanofibers allows use in a continuous operation mode.

  4. Effect of sunlight irradiation on photocatalytic pyrene degradation in contaminated soils by micro-nano size TiO2

    Chang Chien, S.W.; Chang, C.H.; Chen, S.H.; Wang, M.C.; Madhava Rao, M.; Satya Veni, S.

    2011-01-01

    The enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils by micro-nano size TiO 2 in the presence and absence of sunlight was investigated. The results showed that the synergistic effect of sunlight irradiation and TiO 2 was more efficient on pyrene degradation in quartz sand and red and alluvial soils than the corresponding reaction system without sunlight irradiation. In the presence of sunlight irradiation, the photooxidation (without TiO 2 ) of pyrene was very pronounced in alluvial and red soils and especially in quartz sand. However, in the absence of sunlight irradiation, the catalytic pyrene degradation by TiO 2 and the photooxidation (without TiO 2 ) of pyrene were almost nil. This implicates that ultra-violet (UV) wavelength range of sunlight plays an important role in TiO 2 -enhanced photocatalytic pyrene degradation and in photooxidation (without TiO 2 ) of pyrene. The percentages of photocatalytic pyrene degradation by TiO 2 in quartz sand, alluvial and red soils under sunlight irradiation were 78.3, 23.4, and 31.8%, respectively, at 5 h reaction period with a 5% (w/w) dose of the amended catalyst. The sequence of TiO 2 -enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils was quartz sand > red soil > alluvial soil, due to different texture and total organic carbon (TOC) contents of the quartz sand and other two soils. The differential Fourier transform infrared (FT-IR) spectra of degraded pyrene in alluvial soil corroborate that TiO 2 -enhanced photocatalytic degradation rate of degraded pyrene was much greater than photooxidation (without TiO 2 ) rate of degraded pyrene. Based on the data obtained, the importance for the application of TiO 2 -enhanced photocatalytic pyrene degradation and associated organic contaminants in contaminated soils was elucidated. - Highlights: → Synergistic effect of sunlight irradiation and TiO 2 promoted degradation of pyrene. → Micro-nano size TiO 2 enhanced

  5. Study on microwave assisted process in chemical extraction

    Amer Ali; Rosli Mohd Yunus; Ramlan Abd Aziz

    2001-01-01

    The microwave assisted process is a revolutionary method of extraction that reduces the extraction time to as little as a few seconds, with up to a ten-fold decrease in the use of solvents. The target material is immersed in solvent that is transparent to microwaves, so only the target material is heated, and because of the microwaves tend to heat the inside of the material quickly, the target chemical are expelled in a few seconds. benefits from this process include significant reductions in the amount of energy required and substantial reductions in the cost and dispose of hazardous solvents. A thorough review has been displayed on: using the microwave in extraction, applications of microwave in industry, process flow diagram, mechanism of the process and comparison between microwave process and other extraction techniques (soxhlet, steam distillation and supercritical fluid). This review attempts to summarize the studies about microwave assisted process as a very promising technique. (Author)

  6. Process characteristics for microwave assisted hydrothermal carbonization of cellulose.

    Zhang, Junting; An, Ying; Borrion, Aiduan; He, Wenzhi; Wang, Nan; Chen, Yirong; Li, Guangming

    2018-07-01

    The process characteristics of microwave assisted hydrothermal carbonization of cellulose was investigated and a first order kinetics model based on carbon concentration was developed. Chemical properties analysis showed that comparing to conventional hydrothermal carbonization, hydrochar with comparable energy properties can be obtained with 5-10 times decrease in reaction time with assistance of microwave heating. Results from kinetics study was in great agreement with experimental analysis, that they both illustrated the predominant mechanism of the reaction depend on variations in the reaction rates of two co-existent pathways. Particularly, the pyrolysis-like intramolecular dehydration reaction was proved to be the predominant mechanism for hydrochar generation under high temperatures. Finally, the enhancement effects of microwave heating were reflected under both soluble and solid pathways in this research, suggesting microwave-assisted hydrothermal carbonization as a more attracting method for carbon-enriched hydrochar recovery. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Microwave-assisted Weak Acid Hydrolysis of Proteins

    Miyeong Seo

    2012-06-01

    Full Text Available Myoglobin was hydrolyzed by microwave-assisted weak acid hydrolysis with 2% formic acid at 37 oC, 50 oC, and100 oC for 1 h. The most effective hydrolysis was observed at 100 oC. Hydrolysis products were investigated using matrixassistedlaser desorption/ionization time-of-flight mass spectrometry. Most cleavages predominantly occurred at the C-termini ofaspartyl residues. For comparison, weak acid hydrolysis was also performed in boiling water for 20, 40, 60, and 120 min. A 60-min weak acid hydrolysis in boiling water yielded similar results as a 60-min microwave-assisted weak acid hydrolysis at100 oC. These results strongly suggest that microwave irradiation has no notable enhancement effect on acid hydrolysis of proteinsand that temperature is the major factor that determines the effectiveness of weak acid hydrolysis.

  8. Facile fabrication of ordered mesoporous graphitic carbon nitride for RhB photocatalytic degradation

    Luo, Lei; Zhang, Anfeng [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Janik, Michael J. [EMS Energy Institute, PSU-DUT Joint Center for Energy Research and Department of Energy & Mineral Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Li, Keyan [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Song, Chunshan [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); EMS Energy Institute, PSU-DUT Joint Center for Energy Research and Department of Energy & Mineral Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Guo, Xinwen, E-mail: guoxw@dlut.edu.cn [State Key Laboratory of Fine Chemicals, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2017-02-28

    Highlights: • Ordered mesoporous graphitic carbon nitrides with S{sub BET} = 279.3 m{sup 2}/g were prepared. • Enhanced photocatalytic activity and reusability were presented. • Improved S{sub BET} and charge carrier separation efficiency contribute to the activity. - Abstract: Ordered mesoporous graphitic carbon nitrides were prepared by directly condensing the uniform mixtures of melamine and KIT-6. After removal of the KIT-6 sacrificial template, the carbon nitrides were characterized with TEM, N{sub 2} physical adsorption, XRD, FT-IR, XPS, UV–vis and PL spectrometries, and tested for their RhB photocatalytic degradation activity. Together, these characterizations confirmed the as-prepared tunable mesoporous materials with enhanced charge separation efficiency and superior photocatalytic performance. Compared with a conventional bulk g-C{sub 3}N{sub 4}, ordered mesoporous g-C{sub 3}N{sub 4} exhibits a larger specific surface area of 279.3 m{sup 2}/g and a pore size distribution about 4.0 nm and 13.0 nm. Meanwhile, the reduced bandgap energy of 2.77 eV and lower photogenerated electron-hole pair recombination frequency were evidenced by UV–Vis and PL spectra. The RhB photocatalytic degradation activity maximizes with a mass ratio of KIT-6/melamine of 80% (KCN80), and the kinetic constant reaches 0.0760 min{sup −1} which is 16 times higher than that of the bulk sample. Reusability of KCN80 was demonstrated by a lack of evident deactivation after three consecutive reaction periods. The direct condensation of the KIT-6 and melamine mixture does not require pre-casting of the precursor into the pore system of the templates. Owing to its high product yield, improved S{sub BET}, reduced bandgap energy and limited charge recombination, the facile-prepared ordered mesoporous g-C{sub 3}N{sub 4} is a practical candidate for further modification.

  9. Microwave Assisted Manufacturing and Repair of Carbon Reinforced Nanocomposites

    Sosa, Edward D.; Worthy, Erica S.; Darlington, Thomas K.

    2016-01-01

    We report a composite capable of advanced manufacturing and damage repair. Microwave energy is used to induce thermal reversible polymerization of the matrix allowing for microwave assisted composite welding and repair. Composites can be bonded together in just a few minutes through microwave welding. Lap shear testing demonstrates that microwave welded composites exhibit 40% bond strength relative to composites bonded with epoxy resin. Double cantilever beam testing shows 60% recovery in del...

  10. Fast preparation of Bi2GeO5 nanoflakes via a microwave-hydrothermal process and enhanced photocatalytic activity after loading with Ag nanoparticles

    Li, Zhao-Qian; Lin, Xin-Shan; Zhang, Lei; Chen, Xue-Tai; Xue, Zi-Ling

    2012-01-01

    Highlights: ► Bi 2 GeO 5 nanoflakes were successfully synthesized via a microwave-assisted solution-phase approach. ► Ag nanoparticles were deposited on the Bi 2 GeO 5 nanoflakes by a photoreduction procedure. ► Catalytic activity of the Ag/Bi 2 GeO 5 nanocomposite in the photo-degradation of rhodamine B (RhB) was much higher than that of pure Bi 2 GeO 5 . -- Abstract: In this work, a facile and rapid microwave-assisted hydrothermal route has been developed to prepare Bi 2 GeO 5 nanoflakes. Ag nanoparticles were subsequently deposited on the Bi 2 GeO 5 nanoflakes by a photoreduction procedure. The phases and morphologies of the products were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy. Photocatalytic experiments indicate that such Ag/Bi 2 GeO 5 nanocomposite possesses higher photocatalytic activity for RhB degradation under UV light irradiation in comparison to pure Bi 2 GeO 5 . The amount of Ag in the nanocomposite affects the catalytic activity, and 3 wt% Ag showed the highest photodegradation efficiency. Moreover, the catalyst remains active after four consecutive tests. The present study provides a new strategy to design composite materials with enhanced photocatalytic activity.

  11. Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

    Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

    2016-12-01

    Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

  12. Photocatalytic degradation of clofibric acid, carbamazepine and iomeprol using conglomerated TiO2 and activated carbon in aqueous suspension.

    Ziegmann, Markus; Frimmel, Fritz H

    2010-01-01

    The combination of powdered activated carbon (PAC) and TiO(2) has been tested for synergistic/antagonistic effects in the photocatalytic degradation of carbamazepine, clofibric acid and iomeprol. Synergistic effects are thought to be caused by rapid adsorption on the PAC surface followed by diffusion to the TiO(2) surface and photocatalytic degradation. The Freundlich constant K(F) was used for comparing the sorption properties of the three substances and it was found that K(F) for clofibric acid was 3 times lower than for carbamazepine and iomeprol, regardless of the kind of PAC used. A PAC with a distinct tendency to form conglomerates was selected so that a high percentage of the PAC surface was in direct proximity to the TiO(2) surface. The photocatalytic degradation of the pharmaceutically active compounds studied followed pseudo-first order kinetics. Synergistic effects only occurred for clofibric acid (factor 1.5) and an inverse relationship between adsorption affinity and synergistic effects was found. High affinity of the target substances to the PAC surface seemed to be counterproductive for the photocatalytic degradation.

  13. Photocatalytic degradation of p-phenylenediamine with TiO2-coated magnetic PMMA microspheres in an aqueous solution

    Chen, Y.-H.; Liu, Y.-Y.; Lin, R.-H.; Yen, F.-S.

    2009-01-01

    This study investigates the photocatalytic degradation of p-phenylenediamine (PPD) with titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO 2 /mPMMA) microspheres. The TiO 2 /mPMMA microspheres are employed as novel photocatalysts with the advantages of high photocatalytic activity, magnetic separability, and good durability. The scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM) images of the TiO 2 /mPMMA microspheres are used to characterize the morphology, element content, and distribution patterns of magnetite and TiO 2 nanoparticles. The BET-specific surface area and saturation magnetization of the TiO 2 /mPMMA microspheres are observed as 2.21 m 2 /g and 4.81 emu/g, respectively. The photocatalytic degradation of PPD are performed under various experimental conditions to examine the effects of initial PPD concentration, TiO 2 /mPMMA microsphere dosage, and illumination condition on the eliminations of PPD and chemical oxygen demand (COD) concentrations. Good repeatability of photocatalytic performance with the use of the TiO 2 /mPMMA microspheres has been demonstrated in the multi-run experiments. The photocatalytic kinetics for the reductions of PPD and COD associated with the initial PPD concentration, UV radiation intensity, and TiO 2 /mPMMA microsphere dosage are proposed. The relationships between the reduction percentages of COD and PPD are clearly presented

  14. Preparation of H3PW12O40/MCM-48 and its photocatalytic degradation of pesticides.

    Liu, Xia; Li, Yan-zhou; Gan, Qiang; Feng, Chang-gen

    2014-08-01

    A composite catalyst H3PW12O40/MCM-48 was prepared by loading photocatalyst phosphotungstic acid H3PW12O40 (HPW) to molecular sieve MCM-48 by impregnation method, and its structure was characterized by Fourier transform infrared (FT-IR) spectra, small angle X-ray diffraction (XRD) patterns, nitrogen adsorption analysis and High-resolution transmission electron microscopy (HRTEM) analysis. Photocatalytic degradation activities of HPW/MCM-48 against pesticides imidacloprid and paraquat were evaluated under UV radiation (365 nm). The results show that HPW/MCM-48 maintains the mesoprous molecular sieve structure of MCM-48 and the Keggin structure of HPW, while the BET surface area is 793.35 m2 x g(-1), pore volume is 1.46 cm3 x g(-1), average pore diameter is 2.76 nm, suggesting loading HPW on MCM-48 is a considerable way to improve its surface area. After 14 h UV irradiation (365 nm), 57.38% imidacloprid and 63.79% paraquat were degraded by 20 mg HPW/MCM-48 catalyst, while HPW and blank group degraded the two pesticides at the degradation rate of about 25% and 5%, respectively. Implying loading on MCM-48 could greaterly improve the degradation activity of HPW. The reslut of degradation kinetics show that, the degradation process of HPW/MCM-48 fits first order kinetics equation. The rate constant Ka of HPW/MCM-48 toward imidacloprid and paraquat are 0.089 h and 0.117 h, with the half-life t(1/2) of 7.8 h and 5.9 h, respectively.

  15. Decolorization of Methylene Blue with TiO2 Sol via UV Irradiation Photocatalytic Degradation

    Jun Yao

    2010-01-01

    Full Text Available TiO2 sol was prepared for the degradation of methylene blue (MB solution under ultraviolet (UV irradiation. The absorption spectra of MB indicated that the maximum wavelength, 663 nm, almost kept the same. The performance of 92.3% for color removal was reached after 160 min. The particle size of TiO2 sol was about 22.5 nm. X-ray diffraction showed that TiO2 consisted of a single anatase phase. The small size and anatase phase probably resulted in high photocatalytic activity of TiO2 sol. The degradation ratio decreased as the initial concentration of MB increased. The photodegradation efficiency decreased in the order of pH 2>pH 9>pH 7. Regarding catalyst load, the degradation increased with the mass of catalyst up to an amount of 1.5 g⋅L−1 then decreased as the mass continued to increase. The addition of H2O2 to TiO2 sol resulted in an increase on the degradation ratio.

  16. Parameters affecting the photocatalytic degradation of dyes using TiO2: a review

    Reza, Khan Mamun; Kurny, ASW; Gulshan, Fahmida

    2017-07-01

    Traditional chemical, physical and biological processes for treating wastewater containing textile dye have such disadvantages as high cost, high energy requirement and generation of secondary pollution during treatment process. The advanced oxidation processes technology has been attracting growing attention for the decomposition of organic dyes. Such processes are based on the light-enhanced generation of highly reactive hydroxyl radicals, which oxidize the organic matter in solution and convert it completely into water, CO2 and inorganic compounds. In this presentation, the photocatalytic degradation of dyes in aqueous solution using TiO2 as photocatalyst under solar and UV irradiation has been reviewed. It is observed that the degradation of dyes depends on several parameters such as pH, catalyst concentration, substrate concentration and the presence of oxidants. Reaction temperature and the intensity of light also affect the degradation of dyes. Particle size, BET-surface area and different mineral forms of TiO2 also have influence on the degradation rate.

  17. Solid-phase photocatalytic degradation of polyethylene-goethite composite film under UV-light irradiation

    Liu, G.L.; Zhu, D.W.; Liao, S.J.; Ren, L.Y.; Cui, J.Z.; Zhou, W.B.

    2009-01-01

    A novel photodegradable polyethylene-goethite (PE-goethite) composite film was prepared by embedding the goethite into the commercial polyethylene. The degradation of PE-goethite composite films was investigated under ultraviolet light irradiation. The photodegradation activity of the PE plastic was determined by monitoring its weight loss, scanning electron microscopic (SEM) analysis and FT-IR spectroscopy. The weight of PE-goethite (1 wt%) sample steadily decreased and led to the total 16% reduction in 300 h under UV-light intensity for 1 mW/cm 2 . Through SEM observation there were some cavities around the goethite powder in the composite films, but there were few changes except some surface chalking phenomenon in pure PE film. The degradation rate could be controlled by changing the concentration of goethite particles in PE plastic. The degradation of composite plastic initiated on PE-goethite interface and then extended into polymer matrix induced by the diffusion of the reactive oxygen species generated on goethite particle surface. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  18. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC, TiO2/carbon (C, and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, thermogravimetric analysis (TG-DTA, Brunauer-Emmet-Teller (BET, and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1. The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  19. Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

    Ali Nickheslat

    2013-01-01

    Full Text Available Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The effect of important parameters including initial phenol concentration, TiO2 catalyst dose, duration of UV radiation, pH of solution, and contact time was investigated. Results. In the dip-coat lining stage, the produced nanoparticles with anatase crystalline structure have the average particle size of 30 nm and are uniformly distributed over the tube surface. The removal efficiency of phenol was increased with the descending of the solution pH and initial phenol concentration and rising of the contact time. Conclusion. Results showed that the light easily passes through four layers of coating (about 105 nm. The highest removal efficiency of phenol with photocatalytic UV/TiO2 process was 50% at initial phenol concentration of 30 mg/L, solution pH of 3, and 300 min contact time. The comparison of synthetic solution and petrochemical wastewater showed that at same conditions the phenol removal efficiency was equal.

  20. Water-driven micromotors for rapid photocatalytic degradation of biological and chemical warfare agents.

    Li, Jinxing; Singh, Virendra V; Sattayasamitsathit, Sirilak; Orozco, Jahir; Kaufmann, Kevin; Dong, Renfeng; Gao, Wei; Jurado-Sanchez, Beatriz; Fedorak, Yuri; Wang, Joseph

    2014-11-25

    Threats of chemical and biological warfare agents (CBWA) represent a serious global concern and require rapid and efficient neutralization methods. We present a highly effective micromotor strategy for photocatalytic degradation of CBWA based on light-activated TiO2/Au/Mg microspheres that propel autonomously in natural water and obviate the need for external fuel, decontaminating reagent, or mechanical agitation. The activated TiO2/Au/Mg micromotors generate highly reactive oxygen species responsible for the efficient destruction of the cell membranes of the anthrax simulant Bacillus globigii spore, as well as rapid and complete in situ mineralization of the highly persistent organophosphate nerve agents into nonharmful products. The water-driven propulsion of the TiO2/Au/Mg micromotors facilitates efficient fluid transport and dispersion of the photogenerated reactive oxidative species and their interaction with the CBWA. Coupling of the photocatalytic surface of the micromotors and their autonomous water-driven propulsion thus leads to a reagent-free operation which holds a considerable promise for diverse "green" defense and environmental applications.

  1. Enhanced photocatalytic performance and degradation pathway of Rhodamine B over hierarchical double-shelled zinc nickel oxide hollow sphere heterojunction

    Zhang, Ying; Zhou, Jiabin; Cai, Weiquan; Zhou, Jun; Li, Zhen

    2018-02-01

    In this study, hierarchical double-shelled NiO/ZnO hollow spheres heterojunction were prepared by calcination of the metallic organic frameworks (MOFs) as a sacrificial template in air via a one-step solvothermal method. Additionally, the photocatalytic activity of the as-prepared samples for the degradation of Rhodamine B (RhB) under UV-vis light irradiation were also investigated. NiO/ZnO microsphere comprised a core and a shell with unique hierarchically porous structure. The photocatalytic results showed that NiO/ZnO hollow spheres exhibited excellent catalytic activity for RhB degradation, causing complete decomposition of RhB (200 mL of 10 g/L) under UV-vis light irradiation within 3 h. Furthermore, the degradation pathway was proposed on the basis of the intermediates during the photodegradation process using liquid chromatography analysis coupled with mass spectroscopy (LC-MS). The improvement in photocatalytic performance could be attributed to the p-n heterojunction in the NiO/ZnO hollow spheres with hierarchically porous structure and the strong double-shell binding interaction, which enhances adsorption of the dye molecules on the catalyst surface and facilitates the electron/hole transfer within the framework. The degradation mechanism of pollutant is ascribed to the hydroxyl radicals (rad OH), which is the main oxidative species for the photocatalytic degradation of RhB. This work provides a facile and effective approach for the fabrication of porous metal oxides heterojunction with high photocatalytic activity and thus can be potentially used in the environmental purification.

  2. Synthesis and characterization of high photocatalytic activity and stable Ag3PO4/TiO2 fibers for photocatalytic degradation of black liquor

    Cai, Li; Long, Qiyi; Yin, Chao

    2014-01-01

    Highlights: • Ag 3 PO 4 /TiO 2 fibers were prepared via in situ Ag 3 PO 4 particles onto the surface of TiO 2 fiber. • Ag 3 PO 4 /TiO 2 fibers have stronger catalytic activity and excellent chemical stability. • Ag 3 PO 4 /TiO 2 fibers act as an efficient catalyst for the photocatalytic degradation of black liquor. - Abstract: The TiO 2 fiber was prepared by using cotton fiber as a template, and then Ag 3 PO 4 /TiO 2 fibers were synthesized via in situ Ag 3 PO 4 particles onto the surface of TiO 2 fiber. Their structure and physical properties were characterized by means of scanning electron microscopy (SEM), specific surface analyzer, X-ray diffraction (XRD), UV–vis absorption spectra and photoluminescence spectra (PL). SEM analysis indicated that the well-defined surface morphology of natural cotton fiber was mostly preserved in TiO 2 and Ag 3 PO 4 /TiO 2 fibers. Compared with TiO 2 fiber, the absorbance wavelengths of Ag 3 PO 4 /TiO 2 fibers were apparently red shifted and the PL intensities revealed a significant decrease. By using the photocatalytic degradation of black liquor as a model reaction, the visible light and ultraviolet light catalytic efficiencies of TiO 2 , Ag 3 PO 4 and Ag 3 PO 4 /TiO 2 fibers were evaluated. The reaction results showed that Ag 3 PO 4 /TiO 2 fibers had stronger photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared Ag 3 PO 4 /TiO 2 fibers could act as an efficient catalyst for the photocatalytic degradation of black liquor, which suggested their promising applications. It was proposed that the • OH radicals played the leading role in the photocatalytic degradation of the black liquor by Ag 3 PO 4 /TiO 2 fibers system

  3. Photocatalytic degradation kinetics and mechanism of antivirus drug-lamivudine in TiO{sub 2} dispersion

    An, Taicheng, E-mail: antc99@gig.ac.cn [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); An, Jibin [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Yang, Hai [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Li, Guiying [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Feng, Huixia [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Nie, Xiangping [Institute of Hydrobiology, Jinan University, Guangzhou 510632 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Photocatalytic degradation kinetics of antivirus drug lamivudine. Black-Right-Pointing-Pointer The degradation kinetics was optimized by the single-variable-at-a-time. Black-Right-Pointing-Pointer The degradation kinetics was optimized by central composite design. Black-Right-Pointing-Pointer The contribution of reactive species was investigated with addition of scavengers. Black-Right-Pointing-Pointer Six intermediates were identified and a degradation mechanism was proposed. - Abstract: Photocatalytic degradation kinetics of antivirus drug-lamivudine in aqueous TiO{sub 2} dispersions was systematically optimized by both single-variable-at-a-time and central composite design based on the response surface methodology. Three variables, TiO{sub 2} content, initial pH and lamivudine concentration, were selected to determine the dependence of degradation efficiencies of lamivudine on independent variables. Response surface methodology modeling results indicated that degradation efficiencies of lamivudine were highly affected by TiO{sub 2} content and initial lamivudine concentration. The highest degradation efficiency was achieved at suitable amount of TiO{sub 2} and with maintaining initial lamivudine concentration to a minimum. In addition, the contribution experiments of various primary reactive species produced during the photocatalysis were investigated with the addition of different scavengers and found that hydroxyl radicals was the major reactive species involved in lamivudine degradation in aqueous TiO{sub 2}. Six degradation intermediates were identified using HPLC/MS/MS, and photocatalytic degradation mechanism of lamivudine was proposed by utilizing collective information from both experimental results of HPLC/MS/MS, ion chromatography as well as total organic carbon and theoretical data of frontier electron densities and point charges.

  4. Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO{sub 2}

    Ozmen, Murat, E-mail: murat.ozmen@inonu.edu.tr [Inonu University, Faculty of Science, Department of Biology, Malatya (Turkey); Güngördü, Abbas [Inonu University, Faculty of Science, Department of Biology, Malatya (Turkey); Erdemoglu, Sema [Inonu University, Faculty of Science, Department of Chemistry, Malatya (Turkey); Ozmen, Nesrin [Inonu University, Faculty of Education, Department of Science Teaching Program, Malatya (Turkey); Asilturk, Meltem [Akdeniz University, Department of Materials Science and Engineering, Antalya (Turkey)

    2015-08-15

    Highlights: • Undoped and Mn-doped TiO{sub 2} nanoparticles were synthesized and characterized. • The photocatalytic efficiency of the photocatalysts was evaluated for BPA and ATZ. • Toxicity of photocatalysts and photocatalytic by-products were determined. • Mn-doped TiO{sub 2} nanoparticles did not cause significant lethality on X. laevis. • Degradation of BPA caused a significant reduction of lethal effects. - Abstract: The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO{sub 2}. Undoped and Mn-doped TiO{sub 2} nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV–vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO{sub 2} was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO{sub 2} nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO{sub 2} increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2–4 h of degradation. However, biochemical assays showed that both Mn-doped TiO{sub 2} and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn

  5. Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-01-01

    Bismuth selenide (Bi2Se3) and nickel (Ni) doped Bi2Se3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi2Se3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi2Se3 sample exhibited higher photo-catalytic activity than that of the pure Bi2Se3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi2Se3 in presence of hydrogen peroxide (H2O2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

  6. Thickness-dependent photocatalytic performance of graphite oxide for degrading organic pollutants under visible light.

    Oh, Junghoon; Chang, Yun Hee; Kim, Yong-Hyun; Park, Sungjin

    2016-04-28

    Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication. All GO samples exhibit photocatalytic activity for degrading an organic pollutant, rhodamine B under visible light, and the thickest sample shows the best catalytic performance. UV-vis-NIR diffuse reflectance absorption spectra indicate that thicker GO samples absorb more vis-NIR light than thinner ones. Density-functional theory calculations show that GO has a much smaller band gap than that of single-layer graphene oxide, and thus suggest that the largely-reduced band gap is responsible for this trend of light absorption.

  7. Graphene-SnO2 composites for highly efficient photocatalytic degradation of methylene blue under sunlight.

    Seema, Humaira; Christian Kemp, K; Chandra, Vimlesh; Kim, Kwang S

    2012-09-07

    Graphene sheets decorated with SnO(2) nanoparticles (RGO-SnO(2)) were prepared via a redox reaction between graphene oxide (GO) and SnCl(2). Graphene oxide (GO) was reduced to graphene (RGO) and Sn(2+) was oxidized to SnO(2) during the redox reaction, leading to a homogeneous distribution of SnO(2) nanoparticles on RGO sheets. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show uniform distribution of the nanoparticles on the RGO surface and high-resolution transmission electron microscopy (HRTEM) shows an average particle size of 3-5 nm. The RGO-SnO(2) composite showed an enhanced photocatalytic degradation activity for the organic dye methylene blue under sunlight compared to bare SnO(2) nanoparticles. This result leads us to believe that the RGO-SnO(2) composite could be used in catalytic photodegradation of other organic dyes.

  8. Nanostructure CdS/ZnO heterojunction configuration for photocatalytic degradation of Methylene blue

    Velanganni, S.; Pravinraj, S.; Immanuel, P.; Thiruneelakandan, R.

    2018-04-01

    In the present manuscript, thin films of Zinc Oxide (ZnO) have been deposited on a FTO substrate using a simple successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) method. Cadmium Sulphide (CdS) nanoparticles are sensitized over ZnO thin films using SILAR method. The synthesized nanostructured CdS/ZnO heterojunction thin films was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and Raman spectroscopy techniques. The band gap of CdS nanoparticles over ZnO nanostructure was found to be about 3.20 eV. The photocatalytic activities of the deposited CdS/ZnO thin films were evaluated by the degradation of methylene blue (MB) in an aqueous solution under sun light irradiation.

  9. Optimization of Nano-TiO Photocatalytic Reactor for Organophosphorus Degradation

    Ilin Sadeghi

    2012-01-01

    Full Text Available The photocatalytic decontamination of triethyl phosphate (TEP is studied by the UV/nano-TiO2 process. The nano-TiO2 concentration and pH value for the complete oxidation of TEP were investigated in different concentrations of TEP. The kinetic reaction was calculated for TEP as a function of initial concentration of TEP. Results of adsorptions showed that TEP was adsorbed better in alkalinity pH, and the natural pH had the highest reaction rate for complete degradation. Also, the zero-kinetic order with the lag time as a function of initial concentration of TEP and TiO2 was suggested for oxidation of TEP. The optimized concentration of nano-TiO2 was 400 mg/lit which had the best conversion and the lowest lag time in the reaction.

  10. Kinetic modeling of the photocatalytic degradation of clofibric acid in a slurry reactor.

    Manassero, Agustina; Satuf, María Lucila; Alfano, Orlando Mario

    2015-01-01

    A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.

  11. Reusability Performance of Zinc Oxide Nanoparticles for Photocatalytic Degradation of POME

    Zarifah Zainuri, Nur; Hanis Hayati Hairom, Nur; Abu Bakar Sidik, Dilaelyana; Misdan, Nurasyikin; Yusof, Norhaniza; Wahab Mohammad, Abdul

    2018-03-01

    Performance and reusability of different zinc oxide nanoparticles (ZnO-PVP and ZnO-PEG) for photocatalytic degradation of palm-mill oil effluent (POME) has been studied. The nanoparticles properties were characterised with fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM results show that ZnO-PEG nanoparticles exhibit the smaller size than ZnO-PVP with less agglomeration. It was found that ZnO-PEG shows better effectiveness than ZnO-PVP in reducing turbidity, colour and increasing the dissolved oxygen (DO). By using two types of reusability methods: (a) oven drying (b) hot water rinsing, the oven drying method portrayed the most efficient route for POME treatment. This research would be a solution to the palm oil industry for photocatalyst recovering as well as reduction of the chemical usage in order to meet the development of advanced and greener technologies.

  12. Effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interface temperature and surface energy

    Tong Wen

    Full Text Available The microwave-assisted leaching was a new approach to intensify the copper recovery from chalcopyrite by hydrometallurgy. In this work, the effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interfacial reaction temperature and surface energy were investigated. The activation energy of chalcopyrite leaching was affected indistinctively by the microwave-assisted heating (39.1 kJ/mol compared with the conventional heating (43.9 kJ/mol. However, the boiling point of the leaching system increased through microwave-assisted heating. Because of the improved boiling point and the selective heating of microwave, the interfacial reaction temperature increased significantly, which gave rise to the increase of the leaching recovery of copper. Moreover, the surface energy of the chalcopyrite through microwave-assisted heating was also enhanced, which was beneficial to strengthen the leaching of chalcopyrite. Keywords: Microwave-assisted heating, Chalcopyrite, Leaching kinetics, Interface temperature, Surface energy

  13. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    Ranfang Zuo

    2014-01-01

    Full Text Available Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with diatomite and degrading them with TiO2. Scanning electron microscopy (SEM, energy dispersive spectrum (EDS, X-ray diffraction (XRD, chemical analysis, and Fourier transform infrared spectrometry (FTIR indicated that TiO2 was impregnated well on the surface of diatomite. Furthermore, TiO2/diatomite was more active than nano-TiO2 for the degradation of methylene blue (MB in solution. MB at concentrations of 15 and 35 ppm can be completely degraded in 20 and 40 min, respectively.

  14. Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst.

    Helaïli, N; Boudjamaa, A; Kebir, M; Bachari, K

    2017-03-01

    The present study focused on the evaluation of photo-catalytic and photo-electrochemical properties of the photo-catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico-chemical, optical, electrical, electrochemical, and photo-electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott-shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m 2 /g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo-degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.

  15. Photocatalytic degradation of furfural in aqueous solution by N-doped titanium dioxide nanoparticles.

    Veisi, Farzaneh; Zazouli, Mohammad Ali; Ebrahimzadeh, Mohammad Ali; Charati, Jamshid Yazdani; Dezfoli, Amin Shiralizadeh

    2016-11-01

    The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO 2 /Sun and N-TiO 2 /UV) in a lab-scale batch photoreactor. The N-TiO 2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO 2 /UV and N-TiO 2 /Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO 2 /UV process was higher than that using the N-TiO 2 /Sun process.

  16. Adsorption and Photocatalytic Decomposition of the β-Blocker Metoprolol in Aqueous Titanium Dioxide Suspensions: Kinetics, Intermediates, and Degradation Pathways

    Violette Romero

    2013-01-01

    Full Text Available This study reports the photocatalytic degradation of the β-blocker metoprolol (MET using TiO2 suspended as catalyst. A series of photoexperiments were carried out by a UV lamp, emitting in the 250–400 nm range, providing information about the absorption of radiation in the photoreactor wall. The influence of the radiation wavelength on the MET photooxidation rate was investigated using a filter cutting out wavelengths shorter than 280 nm. Effects of photolysis and adsorption at different initial pH were studied to evaluate noncatalytic degradation for this pharmaceutical. MET adsorption onto titania was fitted to two-parameter Langmuir isotherm. From adsorption results it appears that the photocatalytic degradation can occur mainly on the surface of TiO2. MET removed by photocatalysis was 100% conditions within 300 min, while only 26% was achieved by photolysis at the same time. TiO2 photocatalysis degradation of MET in the first stage of the reaction followed approximately a pseudo-first-order model. The major reaction intermediates were identified by LC/MS analysis such as 3-(propan-2-ylaminopropane-1,2-diol or 3-aminoprop-1-en-2-ol. Based on the identified intermediates, a photocatalytic degradation pathway was proposed, including the cleavage of side chain and the hydroxylation addition to the parent compounds.

  17. Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

    Dong Dianbo; Li Peijun; Li Xiaojun; Zhao Qing; Zhang Yinqiu; Jia Chunyun; Li Peng

    2010-01-01

    Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

  18. Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole on nanocrystalline titania films in alkaline media: Effect of applied electrical bias on degradation and transformation products

    Tantis, Iosif [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Bousiakou, Leda [Department of Physics and Astronomy, King Saud University, Riyadh (Saudi Arabia); Department of Automation Engineering, Technological Educational Institute of Pireaus, GR-12244 Athens (Greece); Frontistis, Zacharias; Mantzavinos, Dionissios [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); Konstantinou, Ioannis; Antonopoulou, Maria [Department of Environmental and Natural Resources Management, University of Patras, GR-30100 Agrinio (Greece); Karikas, George-Albert [Department of Medical Laboratories Technology, Technological Educational Institute of Athens, 12210 Athens (Greece); Lianos, Panagiotis, E-mail: lianos@upatras.gr [Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras (Greece); FORTH/ICE-HT, P.O. Box 1414, GR-26504 Patras (Greece)

    2015-08-30

    Highlights: • Photocatalytic and photoelectrocatalytic degradation of the proton pump omeprazole. • Improvement of photocatalysis rate by applying a moderate forward bias. • Highlighting of the advantages of photoelectrocatalysis in a straightforward manner. • HPLC and HR-LC–MS analysis of transformation products. - Abstract: Photocatalytic and photoelectrocatalytic degradation of the drug omeprazole has been studied in the presence of nanocrystalline titania films supported on glass slides or transparent FTO electrodes in alkaline environment. Its photocatalytic degradation rate was assessed by its UV absorbance and by HPLC, while its transformation products were analyzed by HR-LC–MS. Based on UV absorbance, omeprazole can be photocatalytically degraded at an average rate of 6.7 × 10{sup −4} min{sup −1} under low intensity UVA irradiation of 1.5 mW cm{sup −2} in the presence of a nanoparticulate titania film. This corresponds to degradation of 1.4 mg of omeprazole per gram of the photocatalyst per liter of solution per hour. The photodegradation rate can be accelerated in a photoelectrochemical cell by applying a forward bias. In this case, the maximum rate reached under the present conditions was 11.6 × 10{sup −4} min{sup −1} by applying a forward bias of +0.6 V vs. Ag/AgCl. Four major transformation products were successfully identified and their profiles were followed by HR-LC–MS. The major degradation path includes the scission of the sulfoxide bridge into the corresponding pyridine and benzimidazole ring derivates and this is accompanied by the release of sulfate anions in the reaction mixture.

  19. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail: yhshen@ahu.edu.cn

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  20. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua

    2016-01-01

    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu_2O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu_2O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu_2O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu_2O nanoparticles), or two component systems (RGO/Cu_2O composite hydrogel and PANI/Cu_2O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu_2O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu_2O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  1. Photocatalytic Degradation of Alkyle Benzene Solfunate (LAS from Aqueous Solution Using TiO2 Nanoparticles

    Ramin Nabi Zadeh

    2013-03-01

    Full Text Available The Anionic detergents are synthetic organic chemicals used in high volumes in household cleaning products. Alkyle benzene Solfunate (LAS detergent is one of the most widely used anionic surfactants due to excellent cleaning properties. LAS can be toxic to aquatic organisms and bio-accumulated in some fish,and eventually spread through ecosystems using food chain. Thus it should be removed from wastewater before discharge direct to the environment. Photocatalyst degradation process is one the advanced technologies in removal of organic materials from water and wastewater.The aim of this study was the applicability of photodegradations of anionic detergent by use of TiO2 nanoparticles and their change in to the nontoxic materials such as H2O and CO2 in a slurry reactor. LAS solution (10mg/L was prepared and in separated stages was exposed to UV and TiO2 and a combination of them. Also the effect of initial LAS concentration, TiO2 loading, pH and various type of UV irradiation on degradation rate were studied. Maximum degradation was obtained at acidic pH, 50 mg/l of TiO2 and 30 min irradiation time, It was also found 99.5% of LAS was degradated in optimal conditions. Kinetics analysis indicated that photocatalytic degradation rates of LAS can be approximated by pseudo-first order model. The mineralization of LAS was reported by measuring the initial and final COD of illuminated solution. Based on the results, UV/TiO2 process may be effectively applied in LAS removal in low concentration but for high concentration not recommended due to economic reasons.

  2. Photocatalytic activity of porous multiwalled carbon nanotube-TiO{sub 2} composite layers for pollutant degradation

    Zouzelka, Radek [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Department of Physical Chemistry, University of Chemistry and Technology Prague, 16628 Prague (Czech Republic); Kusumawati, Yuly [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Remzova, Monika [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Department of Physical Chemistry, University of Chemistry and Technology Prague, 16628 Prague (Czech Republic); Rathousky, Jiri [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Pauporté, Thierry, E-mail: thierry.pauporte@chimie-paristech.fr [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France)

    2016-11-05

    Highlights: • A simple method for TiO{sub 2}/graphene nanocomposite layer preparation. • Stable coatings on glass substrate. • Mesoporous nanocomposite films with high internal surface area. • High photoactivity for 4-chlorophenol degradation. • Analysis of photocatalysis enhancement mechanism. - Abstract: TiO{sub 2} nanoparticles are suitable building blocks nanostructures for the synthesis of porous functional thin films. Here we report the preparation of films using brookite, P25 titania and anatase pristine nanoparticles and of nanocomposite layers combining anatase nanoparticles and multi-walled carbon nanotube (MWCNT) at various concentrations. The structure and phase composition of the layers were characterized by X-ray diffraction and Raman spectroscopy. Their morphology and texture properties were determined by scanning electron microscopy and krypton adsorption experiments, respectively. Additionally to a strong absorption in the UV range, the composites exhibited light absorption in the visible range as well. The photocatalytic performance of the layers was tested in the degradation of aqueous solutions of 4-chlorophenol serving as a model of an eco-persistent pollutant. Besides the determination of the decrease in the concentration of 4-chlorophenol, also the formation of intermediate degradation products, namely hydroquinone and benzoquinone, was followed. The presence of MWCNTs had a beneficial effect on the photocatalytic performance, a marked increase in the photocatalytic degradation rate constant being observed even at very low concentrations of MWCNTs. Compared to a P25 reference layer, the first order rate reaction constant increased by about 100% for the composite films containing MWCNTs at concentrations above 0.6 wt%. The key parameters for the enhancement of the photocatalytic performance are discussed. The presence of carbon nanotubes influences beneficially the degradation of 4-chlorophenol by an attack of the primarily

  3. Morphological influence of TiO{sub 2} nanostructures (nanozigzag, nanohelics and nanorod) on photocatalytic degradation of organic dyes

    Khan, Sadaf Bashir; Hou, Mengjing; Shuang, Shuang; Zhang, Zhengjun, E-mail: zjzhang@tsinghua.edu.cn

    2017-04-01

    Highlights: • Glancing angle deposition technique is used to fabricate various columnar nanostructures in a single step to tune physiochemical properties. • Enhanced surface area induces porosity, with dispersion of active sites at different length scales of pores. • The increase interface between nanostructures and organic dye is promising factor to enhance photocatalytic degradation. • Morphologies having high surface to volume ratio increases the number of catalytic reaction sites to facilitate organic molecules adsorption favorable for reaction kinetics. - Abstract: Hierarchical nanostructures have drawn significant attention and incredible performance in photodriven chemical conversion area due to its unique physicochemical properties. Herein, we study the morphological influence of TiO{sub 2} nanostructures on photocatalytic degradation of different organic dyes methyl blue, methyl violet and methyl orange present in industrial wastewater. Nanorod, nanohelics and nanozigzag TiO{sub 2} nanofilms were fabricated by using galancing angle deposition technique (GLAD). TiO{sub 2} nanofilms were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and raman analysis. BET surface area analysis were carried out by using nitrogen adsorption desorption curves. The results show that TiO{sub 2} morphology had great influence on photocatalytic degradation of organic dyes due to difference in specific surface area and pore volume of nanostructures. The photocatalytic degradation experiments were carried out for three hours under UV–vis light irradiation. Catalysis recycling and organic dyes concentration influence were also studied. In case of high concentration of organic dyes, negligible degradation rate is observed. TiO{sub 2} nanozigzag films show better degradation performance than nanohelics and nanorod due to presence of large surface area for reaction, higher porosity with dispersion of active sites at different length

  4. Hydrogenated TiO{sub 2} nanobelts as highly efficient photocatalytic organic dye degradation and hydrogen evolution photocatalyst

    Tian, Jian [School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Leng, Yanhua [State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Cui, Hongzhi, E-mail: cuihongzhi1965@163.com [School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); Liu, Hong, E-mail: hongliu@sdu.edu.cn [State key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

    2015-12-15

    Highlights: • A facile synthesis of hydrogenated TiO{sub 2} nanobelts is reported. • Utilizing UV and visible light in photocatalytic degradation and H{sub 2} production. • The improved photocatalytic property is owe to Ti{sup 3+} ions and oxygen vacancies. - Abstract: TiO{sub 2} nanobelts have gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Here we report the facile synthesis of hydrogenated TiO{sub 2} (H-TiO{sub 2}) nanobelts, which exhibit excellent UV and visible photocatalytic decomposing of methyl orange (MO) and water splitting for hydrogen production. The improved photocatalytic property can be attributed to the Ti{sup 3+} ions and oxygen vacancies in TiO{sub 2} nanobelts created by hydrogenation. Ti{sup 3+} ions and oxygen vacancies can enhance visible light absorption, promote charge carrier trapping, and hinder the photogenerated electron–hole recombination. This work offers a simple strategy for the fabrication of a wide solar spectrum of active photocatalysts, which possesses significant potential for more efficient photodegradation, photocatalytic water splitting, and enhanced solar cells using sunlight as light source.

  5. A three-dimensional graphene-TiO{sub 2} nanotube nanocomposite with exceptional photocatalytic activity for dye degradation

    Zhao, Fenghuan [Institute of Material Science and Engineering, Ocean University of China, 266000 Qingdao (China); Dong, Bohua, E-mail: dongbohua@ouc.edu.cn [Institute of Material Science and Engineering, Ocean University of China, 266000 Qingdao (China); Gao, Rongjie; Su, Ge; Liu, Wei [Institute of Material Science and Engineering, Ocean University of China, 266000 Qingdao (China); Shi, Liang [College of Chemistry and Chemical Engineering, Ocean University of China, 266000 Qingdao (China); Xia, Chenghui [Debye Institute, Utrecht University, Princetonplein 1, 3584 CC Utrecht (Netherlands); Cao, Lixin, E-mail: caolixin@ouc.edu.cn [Institute of Material Science and Engineering, Ocean University of China, 266000 Qingdao (China)

    2015-10-01

    Highlights: • A new kind of three-dimensional graphene/TiO{sub 2} nanotube composites were fabricated by facile hydrothermal method. • The graphene with optimized amount has a great influence on the photocatalytic activity of TiO{sub 2}. • The special and well-structured composites nanomaterials have outstanding photocatalytic activity. - Abstract: Three dimensional nanocomposites made up of TiO{sub 2} nanotubes (TNTs) and conducting reduced graphene oxide nanosheets (RGO) were fabricated successfully via hydrothermal method. These graphene/TNTs nanocomposites (GTNCs) with unique nanostructure not only provided sufficient active sites but supplied electron-transport path, Which gave big rise to their photocatalytic activity. In addition, the graphene amount and calcination temperature were intensively optimized. A series of products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. The photocatalytic activity of as-prepared GTNCs was investigated through the degradation of methyl orange (MO) under UV-light irradiation. The results show that these GTNCs are well-structured with outstanding photocatalytic activity which is much better than that of traditional TiO{sub 2} nanotubes.

  6. Enhanced photocatalytic degradation of norfloxacin in aqueous Bi2WO6 dispersions containing nonionic surfactant under visible light irradiation

    Tang, Lin; Wang, Jiajia; Zeng, Guangming; Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi

    2016-01-01

    Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi 2 WO 6 dispersions under visible light irradiation (400–750 nm). • Cu 2+ (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi 2 WO 6 was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi 2 WO 6 dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi 2 WO 6 surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

  7. Microwave-assisted pyrolysis of biomass for liquid biofuels production

    Yin, Chungen

    2012-01-01

    Production of 2nd-generation biofuels from biomass residues and waste feedstock is gaining great concerns worldwide. Pyrolysis, a thermochemical conversion process involving rapid heating of feedstock under oxygen-absent condition to moderate temperature and rapid quenching of intermediate products......, is an attractive way for bio-oil production. Various efforts have been made to improve pyrolysis process towards higher yield and quality of liquid biofuels and better energy efficiency. Microwave-assisted pyrolysis is one of the promising attempts, mainly due to efficient heating of feedstock by ‘‘microwave...

  8. Microwave-assisted extraction of polycyclic aromatic compounds from coal.

    Kerst, M; Andersson, J T

    2001-08-01

    Microwave-assisted extraction (MAE) of polycyclic aromatic compounds (PACs) from coal is shown to give the same pattern of compounds as Soxhlet extraction. MAE requires only 10 mL solvent and 10 min extraction time whereas Soxhlet uses 200 mL and takes 24 h. Although the yields were lower, dichloromethane (DCM) was preferred to pyridine, N-methyl-2-pyrrolidone (NMP), and NMP with CS2 because the pattern of the PACs is shown to be independent of solvent and DCM is a much more convenient solvent to work with.

  9. Optimisation of applied field pulses for microwave assisted magnetic recording

    Simon John Greaves

    2017-05-01

    Full Text Available Grains in a recording medium experience field pulses from a write head during recording. In general, a short head field rise time and a square pulse shape have been viewed as optimal. This work investigates the optimum field pulse shape for microwave assisted magnetic recording on single layer and ECC media. A square pulse was found to give the best recording performance on single layer media, but an initially negative field pulse increasing at a constant rate was more suitable for ECC media.

  10. Microwave-assisted hydrothermal synthesis of lead zirconate fine powders

    Apinpus Rujiwatra

    2011-01-01

    Full Text Available A rapid synthesis of lead zirconate fine powders by microwave-assisted hydrothermal technique is reported. The influences of type of lead precursor, concentration of potassium hydroxide mineraliser, applied microwave power and irradiation time are described. The synthesised powders were characterised by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopic microanalysis and light scattering technique. The merits of the microwave application in reducing reaction time and improving particle mono-dispersion and size uniformity as well as the drawbacks, viz. low purity of the desired phase and increasing demand of mineraliser, are discussed in relation to conventional heating method.

  11. Kinetic analysis on photocatalytic degradation of gaseous acetaldehyde, ammonia and hydrogen sulfide on nanosized porous TiO2 films

    Iis Sopyan

    2007-01-01

    Full Text Available The characteristics of the UV illumination-assisted degradation of gaseous acetaldehyde, hydrogen sulfide, and ammonia on highly active nanostructured-anatase and rutile films were investigated. It was found that the anatase film showed a higher photocatalytic activity than the counterpart did, however, the magnitude of difference in the photocatalytic activity of both films decreased in the order ammonia>acetaldehyde>hydrogen sulfide. To elucidate the reasons for the observation, the adsorption characteristics and the kinetics of photocatalytic degradation of the three reactants on both films were analyzed. The adsorption analysis examined using a simple Langmuir isotherm, showed that adsorbability on both films decreased in the order ammonia>acetaldehyde>hydrogen sulfide, which can be explained in terms of the decreasing electron-donor capacity. Acetaldehyde and ammonia adsorbed more strongly and with higher coverage on anatase film (1.2 and 5.6 molecules/nm2, respectively than on rutile (0.6 and 4.7 molecules/nm2, respectively. Conversely, hydrogen sulfide molecules adsorbed more strongly on rutile film (0.7 molecules/nm2 than on anatase (0.4 molecules/nm2. Exposure to UV light illumination brought about the photocatalytic oxidation of the three gases in contact with both TiO2 films, and the decrease in concentration were measured, and their kinetics are analyzed in terms of the Langmuir–Hinshelwood kinetic model. From the kinetic analysis, it was found that the anatase film showed the photocatalytic activities that were factors of ~8 and ~5 higher than the rutile film for the degradation of gaseous ammonia and acetaldehyde, respectively. However, the activity was only a factor of ~1.5 higher for the photodegradation of hydrogen sulfide. These observations are systematically explained by the charge separation efficiency and the adsorption characteristics of each catalyst as well as by the physical and electrochemical properties of each

  12. Enhanced visible light photocatalytic activity of copper-doped titanium oxide–zinc oxide heterojunction for methyl orange degradation

    Dorraj, Masoumeh, E-mail: masidor20@gmail.com [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Alizadeh, Mahdi [UM Power Energy Dedicated Advanced Centre (UMPEDAC), Level 4 Wisma R& D, University of Malaya, Jalan Pantai Baharu, 59990 Kuala Lumpur (Malaysia); Sairi, Nor Asrina, E-mail: asrina@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Basirun, Wan Jefrey [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Goh, Boon Tong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Woi, Pei Meng; Alias, Yatimah [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-08-31

    Highlights: • The novel Cu-TiO{sub 2}/ZnO heterojunction nanocomposite was synthesized for the first time via a two-step process. • The Cu-TiO{sub 2}/ZnO heterostructured nanocomposite exhibited an enhanced visible-light-driven photocatalytic activity for MO degradation. • The heterostructured nanocomposite could be recycled during the degradation of MO in a three-cycle experiment with good stability. - Abstract: A novel Cu-doped TiO{sub 2} coupled with ZnO nanoparticles (Cu-TiO{sub 2}/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO{sub 2}/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra and Brunauer–Emmett–Teller adsorption isotherm techniques. The Cu-TiO{sub 2}/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO{sub 2} and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO{sub 2}/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron−hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  13. Preparation of re-usable photocatalytic filter for degradation of Malachite Green dye under UV and vis-irradiation

    Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

    2007-01-01

    Sn 4+ doped and undoped nano-TiO 2 particles easily dispersed in water were synthesized without using organic solvent by hydrothermal process. Nanostructure-TiO 2 based thin films were prepared on flyswatter substrate, made with stainless steel, by dip-coating technique. The structure, surface and optical properties of the particles and thin films were characterized by element analysis and XRD, BET, SEM and UV/vis/NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that the coated flyswatter has a very high photocatalytic performance for the photodegradation of Malachite Green irradiated with UV and vis-lights. The results also proved that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces are hydrophilic, and the doping of transition metal ion efficiently improved the degradation performance of TiO 2 -coated flyswatter. The photocatalytic performances determined at both irradiation conditions were very good and were almost similar to each other for Sn 4+ doped TiO 2 -coated flyswatter and it can be repeatedly used with increasing photocatalytic activity compared to undoped TiO 2 -coated flyswatter

  14. Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination

    Saravanan, R.; Karthikeyan, S.; Gupta, V.K.; Sekaran, G.; Narayanan, V.; Stephen, A.

    2013-01-01

    The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Highlights: ► Visible light active photocatalyst ► Degradation of methylene blue and methyl orange ► Preparation of composite materials is a simple, fast and cost effective method. ► Nano composite materials ► Degradation of textile waste water

  15. SrTiO3 Nanocube-Doped Polyaniline Nanocomposites with Enhanced Photocatalytic Degradation of Methylene Blue under Visible Light

    Syed Shahabuddin

    2016-02-01

    Full Text Available The present study highlights the facile synthesis of polyaniline (PANI-based nanocomposites doped with SrTiO3 nanocubes synthesized via the in situ oxidative polymerization technique using ammonium persulfate (APS as an oxidant in acidic medium for the photocatalytic degradation of methylene blue dye. Field emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM, thermogravimetric analysis (TGA, X-ray diffraction (XRD, UV–Vis spectroscopy, Brunauer–Emmett–Teller analysis (BET and Fourier transform infrared spectroscopy (FTIR measurements were used to characterize the prepared nanocomposite photocatalysts. The photocatalytic efficiencies of the photocatalysts were examined by degrading methylene blue (MB under visible light irradiation. The results showed that the degradation efficiency of the composite photocatalysts that were doped with SrTiO3 nanocubes was higher than that of the undoped polyaniline. In this study, the effects of the weight ratio of polyaniline to SrTiO3 on the photocatalytic activities were investigated. The results revealed that the nanocomposite P-Sr500 was found to be an optimum photocatalyst, with a 97% degradation efficiency after 90 min of irradiation under solar light.

  16. Low irradiance photocatalytic degradation of toluene in air by screen-printed titanium dioxide layers

    Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Sangiorgi, Alex; Schiavi, Luca

    2013-01-01

    Screen-printed titania photocatalytic layers made from Degussa P25 were studied in order to assess the potential of this deposition technology for the production of catalytic surfaces for airborne pollutant degradation. The deposited catalytic TiO 2 layers were characterized by a low density (about 25% of the titania bulk crystal) typical of very porous films. The study was carried out using toluene at low concentration (12 ppb) as model pollutant and with a low UV-A irradiance level on the sample surface (200 μW cm −2 ). The catalyst layers were deposited on alumina and quartz substrates demonstrating a good catalytic depollution activity. The relationship between the layer thickness and the catalytic activity was studied in the 1 to 6.8 μm range indicating an optimal 3–4 μm film thickness. Thicker layers do not show significant increases in the catalytic activity. The optical transmittance was studied using quartz substrate samples, showing a severely reduced photon flux for layers deeper than 5 μm. The effect of post-printing thermal treatment was studied in the 500–900 °C range, demonstrating good catalytic activity for processing temperatures ≤ 700 °C. These results indicate that the screen-printing process can be a promising technology for the realization of high efficiency photocatalytic materials for air depollution applications at low UV-A irradiance. - Highlights: • Screen-printed TiO 2 has a good catalytic activity in toluene air depollution. • The overall density of screen-printed TiO 2 layer is ∼ 25% of the bulk crystal density. • The catalytic activity is demonstrated at low UV-A irradiance (200 µW cm –2 ). • The catalytic activity is dependent on the layer thickness until ∼ 4 µm thickness. • The catalytic layer has good activity up to 700 °C post-printing thermal treatment

  17. Comparative study of photocatalytic oxidation on the degradation of formaldehyde and fuzzy mathematics evaluation of filters

    Yu, Huili; Zhang, Jieting

    2012-04-01

    In this study, formaldehyde, one of the major volatile organic compounds, is chosen as the target pollutant. The polytetrafluoroethylene (PTFE) filter, a low cost and commonly used material in industry, is employed as the substrate for nano TiO2 photocatalyst coating at room temperature, which has been scarcely used compared to ceramics or glass beads. Furthermore, a specific experimental set-up that is similar to actual air purification system is developed for the testing. The degradation mechanisms of photolysis reaction, adsorption and photocatalytic oxidation reaction on volatile organic compounds are present respectively. The influences of three aspects mentioned above are compared by a serial of experimental data. The high efficiency of volatile organic compounds on the degradation of formaldehyde is assured. Furthermore, the purification characteristics of three kinds of activated carbon filters and PTFE filter with nano TiO2 are evaluated with the method of fuzzy mathematics. In the end, the result shows that the filter with nano TiO2 has the optimal comprehensive performances.

  18. Enhanced photocatalytic degradation of methylene blue on carbon nanotube-TiO{sub 2}-Pd composites

    Kim, Eun Hye; Choi, Hyun Chul [Dept. of Chemistry, Chonnam National University, Gwangju (Korea, Republic of)

    2016-11-15

    Semiconductor-based photocatalysis is recognized as a promising technique for addressing energy and environmental issues. Among various semiconductors, the use of titanium dioxide (TiO-2) as a photocatalyst in solar energy conversion and pollutant degradation has been widely investigated because of its high efficiency, photostability, and low toxicity. However, its practical application is restricted by the intrinsic wide band gap of TiO-2 and the rapid recombination of photogenerated electron–hole pairs. Therefore, several remedial methods have been proposed, such as the doping of TiO{sub 2} with metallic or non-metallic elements, increasing its surface area, sensitization with dyes, and the generation of defect structures. We have successfully prepared CNT–TiO{sub 2}–Pd composites with a simple two-step sol–gel method. We characterized the composites with TEM and XRD, and demonstrated that anatase TiO{sub 2} and metallic Pd nanoparticles were deposited onto the surfaces of the CNTs. The average particle size of these nanoparticles was approximately 3.4 nm. The prepared catalyst was found to exhibit a higher activity in MB photodegradation than the reference systems. The synergy of the combination of CNTs and Pd nanoparticles with TiO{sub 2} provides superior MB degradation. More comprehensive studies of the mechanism for this synergy between the metal nanoparticles and TiO{sub 2} that enhances the photocatalytic activity of CNT–TiO{sub 2} are underway in our laboratory.

  19. Synthesis of nano-TiO2/diatomite composite and its photocatalytic degradation of gaseous formaldehyde

    Zhang, Guangxin; Sun, Zhiming; Duan, Yongwei; Ma, Ruixin; Zheng, Shuilin

    2017-08-01

    The TiO2/diatomite composite was synthesized through a mild hydrolysis of titanyl sulfate. The prepared composite was characterized by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffused reflectance spectroscopy. The results demonstrate that the anatase TiO2 nanopartilces anchored on the surface of diatomite with Ti-O-Si bonds between diatomite and TiO2. The photodegradation of gaseous formaldehyde under UV irradiation by the TiO2/diatomite composite was studied under various operating conditions, including relative humidity, illumination intensity and catalyst amount, which have significant influence on the degradation process. The TiO2/diatomite composite exhibited better photocatalytic activity than pure TiO2, which could be attributed to the favorable nanoparticles dispersibility and strong formaldehyde adsorption capacity. In addition, the composite exhibited outstanding reusability over five cycles. The TiO2/diatomite composite shows great promising application foreground in formaldehyde degradation.

  20. Microwave-assisted extraction of pectin from cocoa peel

    Sarah, M.; Hanum, F.; Rizky, M.; Hisham, M. F.

    2018-02-01

    Pectin is a polymer of d-galacturonate acids linked by β-1,4 glycosidic bond. This study isolates pectin from cocoa peel (Theobroma cacao) using citric acid as solvent by microwave-assisted extraction method. Cocoa peels (moisture content of 10%) with citric acid solution (pH of 1.5) irradiated by microwave energy at various microwave power (180, 300, 450 and 600 W) for 10, 15, 20, 25 and 30 minutes respectively. Pectin obtained from this study was collected and filtrated by adding 96% ethanol to precipitate the pectin. The best results obtained from extraction process using microwave power of 180 Watt for 30 minutes. This combination of power and time yielded 42.3% pectin with moisture content, ash content, weight equivalent, methoxyl content and galacturonate levels were 8.08%, 5%, 833.33 mg, 6.51% and 58,08%, respectively. The result finding suggested that microwave-assisted extraction method has a great potency on the commercial pectin production.

  1. Photocatalytic degradation properties of α-Fe2O3 nanoparticles for dibutyl phthalate in aqueous solution system

    Liu, Yue; Sun, Nan; Hu, Jianshe; Li, Song; Qin, Gaowu

    2018-04-01

    The phthalate ester compounds in industrial wastewater, as kinds of environmental toxic organic pollutants, may interfere with the body's endocrine system, resulting in great harm to humans. In this work, the photocatalytic degradation properties of dibutyl phthalate (DBP) were investigated using α-Fe2O3 nanoparticles and H2O2 in aqueous solution system. The optimal parameters and mechanism of degradation were discussed by changing the morphology and usage amount of catalysts, the dosage of H2O2, pH value and the initial concentration of DBP. Hollow α-Fe2O3 nanoparticles showed the highest degradation efficiency when 30 mg of catalyst and 50 µl of H2O2 were used in the DBP solution with the initial concentration of 13 mg l-1 at pH = 6.5. When the reaction time was 90 min, DBP was degraded 93% for the above optimal parameters. The photocatalytic degradation mechanism of DBP was studied by the gas chromatography-mass spectrometry technique. The result showed that the main degradation intermediates of DBP were ortho-phthalate monobutyl ester, methyl benzoic acid, benzoic acid, benzaldehyde, and heptyl aldehyde when the reaction time was 2 h. DBP and its intermediates were almost completely degraded to CO2 and H2O in 12 h in the α-Fe2O3/ H2O2/UV system.

  2. An AgI@g-C3N4 hybrid core@shell structure: Stable and enhanced photocatalytic degradation

    Liu, Li; Qi, Yuehong; Yang, Jinyi; Cui, Wenquan; Li, Xingang; Zhang, Zisheng

    2015-12-01

    A novel visible-light-active material AgI@g-C3N4 was prepared by ultrasonication/chemisorption method. The core@shell structure AgI@g-C3N4 catalyst showed high efficiency for the degradation of MB under visible light irradiation (λ > 420 nm). Nearly 96.5% of MB was degraded after 120 min of irradiation in the presence of the AgI@g-C3N4 photocatalyst. Superior stability was also observed in the cyclic runs indicating that the as prepared hybrid composite is highly desirable for the remediation of organic contaminated wastewaters. The improved photocatalytic performance is due to synergistic effects at the interface of AgI and g-C3N4 which can effectively accelerate the charge separation and reinforce the photostability of hybrid composite. The possible mechanism for the photocatalytic activity of AgI@g-C3N4 was tentatively proposed.

  3. Photocatalytic degradation mechanisms of self-assembled rose-flower-like CeO2 hierarchical nanostructures

    Sabari Arul, N.; Mangalaraj, D.; Whan Kim, Tae

    2013-01-01

    Hierarchical rose-flower-like CeO 2 nanostructures were formed by using solvothermal and thermal annealing processes. The CeCO 3 OH thin film was transformed into CeO 2 roses due to thermal annealing. CeO 2 nanostructured roses exhibited excellent photocatalytic activity with a degradation rate of 65% for the azo dye acid orange 7 (AO7) under ultraviolet illumination. The fitting of the absorbance maximum versus time showed that the degradation of AO7 obeyed pseudo-first-order reaction kinetics. The enhancement of the photocatalytic activity for the CeO 2 roses was attributed to the high adsorptivity resulting from the surface active sites and special 4f electron configuration.

  4. Kinetic study of photocatalytic degradation of carbamazepine, clofibric acid, iomeprol and iopromide assisted by different TiO2 materials--determination of intermediates and reaction pathways.

    Doll, Tusnelda E; Frimmel, Fritz H

    2004-02-01

    The light-induced degradation of clofibric acid, carbamazepine, iomeprol and iopromide under simulated solar irradiation has been investigated in aqueous solutions suspended with different TiO2 materials (P25 and Hombikat UV100). Kinetic studies showed that P25 had a better photocatalytic activity for clofibric acid and carbamazepine than Hombikat UV100. For photocatalytic degradation of iomeprol Hombikat UV100 was more suitable than P25. The results can be explained by the higher adsorption capacity of Hombikat UV100 for iomeprol. The study also focuses on the identification and quantification of possible degradation products. The degradation process was monitored by determination of sum parameters and inorganic ions. In case of clofibric acid various aromatic and aliphatic degradation products have been identified and quantified. A possible multi-step degradation scheme for clofibric acid is proposed. This study proves the high potential of the photocatalytic oxidation process to transform and mineralize environmentally relevant pharmaceuticals and contrast media in water.

  5. Kinetics of Photocatalytic Degradation of Diuron in Aqueous Colloidal Solutions of Q-TiO2 Particles

    Macounová, Kateřina; Krýsová, Hana; Ludvík, Jiří; Jirkovský, Jaromír

    2003-01-01

    Roč. 156, - (2003), s. 273-282 ISSN 1010-6030 R&D Projects: GA ČR GA203/99/0763; GA ČR GA203/00/D071; GA ČR GA203/02/0983; GA AV ČR IAA4040804 Institutional research plan: CEZ:AV0Z4040901 Keywords : photocatalytic degradation * phenylurea herbicide diuron * Q-TiO2 Subject RIV: CG - Electrochemistry Impact factor: 1.693, year: 2003

  6. Photocatalytic degradation of p-phenylenediamine with TiO{sub 2}-coated magnetic PMMA microspheres in an aqueous solution

    Chen, Y.-H. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Chung-Hsiao E. Road, Taipei 106, Taiwan (China)], E-mail: yhchen1@ntu.edu.tw; Liu, Y.-Y.; Lin, R.-H.; Yen, F.-S. [Department of Chemical and Material Engineering, National Kaohsiung University of Applied Sciences, 415 Chien Kung Road, Kaohsiung 807, Taiwan (China)

    2009-04-30

    This study investigates the photocatalytic degradation of p-phenylenediamine (PPD) with titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO{sub 2}/mPMMA) microspheres. The TiO{sub 2}/mPMMA microspheres are employed as novel photocatalysts with the advantages of high photocatalytic activity, magnetic separability, and good durability. The scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM) images of the TiO{sub 2}/mPMMA microspheres are used to characterize the morphology, element content, and distribution patterns of magnetite and TiO{sub 2} nanoparticles. The BET-specific surface area and saturation magnetization of the TiO{sub 2}/mPMMA microspheres are observed as 2.21 m{sup 2}/g and 4.81 emu/g, respectively. The photocatalytic degradation of PPD are performed under various experimental conditions to examine the effects of initial PPD concentration, TiO{sub 2}/mPMMA microsphere dosage, and illumination condition on the eliminations of PPD and chemical oxygen demand (COD) concentrations. Good repeatability of photocatalytic performance with the use of the TiO{sub 2}/mPMMA microspheres has been demonstrated in the multi-run experiments. The photocatalytic kinetics for the reductions of PPD and COD associated with the initial PPD concentration, UV radiation intensity, and TiO{sub 2}/mPMMA microsphere dosage are proposed. The relationships between the reduction percentages of COD and PPD are clearly presented.

  7. Pyrrole-regulated precipitation of titania nanorods on polymer fabrics for photocatalytic degradation of trace toluene in air

    Gu, Yi-Jie; Wen, Wei; Xu, Yang; Wu, Jin-Ming

    2018-03-01

    When compared with nanoparticulate counterparts, TiO2 thin films with vertically aligned one-dimensional (1D) nanostructures exhibit enhanced photocatalytic activity because of the highly accessible surface area. The perpendicular of the 1D nanostructure reduces the charge migration path and hence the carrier recombination rate, which also contributes to the photocatalytic activity. Furthermore, TiO2 thin films on flexible substrates are more suitable to degrade pollutants in either water or air because of its easy recovery and free-bending shape. In this study, flexible polyethylene fabrics were firstly coated with a sol-gel nanoparticulate TiO2 seed layer. Quasi-aligned TiO2 nanorods were then precipitated homogeneously under an atmospheric pressure and a low temperature not exceeding 80 °C, using a peroxy-titanium complex precursor with the additive of pyrrole. It is found that the density of TiO2 nanorods increased with the increasing amount of pyrrole monomers. The resultant TiO2 film on polyethylene fabrics exhibited a much reduced band gap of ca. 2.86 eV, which can be attributed to the surface oxygen deficiencies. When utilized to assist photocatalytic degradation of trace toluene in air under the UV light illumination, the TiO2 film exhibited a gradually increased photocatalytic activity upon the increasing cycles for up to six, because of the gradual removal of trace organics on the TiO2 surface. The highest photocatalytic efficiency is recorded to be 5 times that of TiO2 nanotube arrays, which are regarded as an excellent photocatalyst for air cleaning.

  8. Characteristics of supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia)

    2010-02-15

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO{sub 2} as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO{sub 2}:ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m{sup 2}/g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  9. Characteristics of supported nano-TiO2/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi; Mohamed, Abdul Rahman

    2010-01-01

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO 2 /ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO 2 as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO 2 :ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m 2 /g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  10. Solid-phase photocatalytic degradation of polystyrene plastic with goethite modified by boron under UV-vis light irradiation

    Liu Guanglong; Zhu Duanwei; Zhou Wenbing; Liao Shuijiao; Cui Jingzhen; Wu Kang; Hamilton, David

    2010-01-01

    A novel photodegradable polyethylene-boron-goethite (PE-B-goethite) composite film was prepared by embedding the boron-doped goethite into the commercial polyethylene. The goethite catalyst was modified by boron in order to improve its photocatalytic efficiency under the ultraviolet and visible light irradiation. Solid-phase photocatalytic degradation of the PE-B-goethite composite film was carried out in an ambient air at room temperature under ultraviolet and visible light irradiation. The properties of composite films were compared with those of the pure PE films and the PE-goethite composite films through performing weight loss monitoring, scanning electron microscope (SEM) analysis, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The photo-induced degradation of PE-B-goethite composite films was higher than that of the pure PE films and the PE-goethite composite films under the UV-irradiation, while there has been little change under the visible light irradiation. The weight loss of the PE-B-goethite (0.4 wt.%) composite film reached 12.6% under the UV-irradiation for 300 h. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  11. An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

    Patole, Shashikant P.; Simõ es, Filipa; Yapici, Tahir; Warsama, Bashir H.; Anjum, Dalaver H.; Da Costa, Pedro M. F. J.

    2015-01-01

    A method for the complete digestion of carbon nanostructures has been demonstrated. Photographs (on the left side) show zirconium crucibles containing SWCNTs with flux of Na2CO3 and K2CO3, before and after microwave fusion; (on the right side) the appearance of the final solutions containing dissolved samples, from microwave-assisted fusion and microwave-assisted acid digestion. These solutions were used for determining the trace elemental impurities by ICP‒OES.

  12. Microwave assisted acid and alkali pretreatment of Miscanthus biomass for biorefineries

    Zongyuan Zhu

    2015-10-01

    Full Text Available Miscanthus is a major bioenergy crop in Europe and a potential feedstock for second generation biofuels. Thermochemical pretreatment is a significant step in the process of converting lignocellulosic biomass into fermentable sugars. In this work, microwave energy was applied to facilitate NaOH and H2SO4 pretreatments of Miscanthus. This was carried out at 180 ℃ in a monomode microwave cavity at 300 W. Our results show that H2SO4 pretreatment contributes to the breakdown of hemicelluloses and cellulose, leading to a high glucose yield. The maximum sugar yield from available carbohydrates during pretreatment is 75.3% (0.2 M H2SO4 20 Min, and glucose yield is 46.7% under these conditions. NaOH and water pretreatments tend to break down only hemicellulose in preference to cellulose, contributing to high xylose yield. Compared to conventional heating NaOH/H2SO4 pretreatment, 12 times higher sugar yield was obtained by using microwave assisted pretreatment within half the time. NaOH pretreatments lead to a significantly enhanced digestibility of the residue, because the effective removal of lignin and hemicellulose makes cellulose fibres more accessible to cellulases. Morphological study of biomass shows that the tightly packed fibres in the Miscanthus were dismantled and exposed under NaOH condition. We studied sugar degradation under microwave assisted H2SO4 conditions. The results shows that 6-8% biomass was converted into levulinic acid (LA during pretreatment, showing the possibility of using microwave technology to produce LA from biomass. The outcome of this work shows great potential for using microwave in the thermo-chemical pretreatment for biomass and also selective production of LA from biomass.

  13. The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode

    Hossein Ali Rangkooy

    2017-01-01

    Full Text Available The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ZnO-SnO2 nanocomposite on activated carbon was determined by the surface area and scanning electron micrograph technique proposed by Brunauer, Emmett, and Teller. The laboratory findings showed that the highest efficiency was 40% for photocatalytic degradation of toluene. The results also indicated that ZnO-SnO2 nano-oxides immobilization on activated carbon had a synergic effect on photocatalytic degradation of toluene. Use of a hybrid photocatalytic system (ZnO/SnO2 nano coupled oxide and application of absorbent (activated carbon may be efficient and effective technique for refinement of toluene from air flow.

  14. Photocatalytic activity of the binary composite CeO{sub 2}/SiO{sub 2} for degradation of dye

    Phanichphant, Sukon [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Nakaruk, Auppatham [Department of Industrial Engineering, Faculty of Engineering, Naresuan University, Phitsanulok 65000 (Thailand); Centre of Excellence for Innovation and Technology for Water Treatment, Naresuan University, Phitsanulok 65000 (Thailand); Channei, Duangdao, E-mail: duangdaoc@nu.ac.th [Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Research Center for Academic Excellence in Petroleum, Petrochemicals and Advanced Materials, Naresuan University, Phitsanulok 65000 (Thailand)

    2016-11-30

    Highlights: • The enhanced photocatalytic activity of the CeO{sub 2}/SiO{sub 2} composite can be explained by the presence of the SiO{sub 2} adsorbent, which effectively increased the surface area of the CeO{sub 2}. • The increased surface area of CeO{sub 2} should be helpful to facilitate more effective adsorption sites, which enhances the photocatalytic degradation of organic pollutant significantly. • SiO{sub 2} modification is effective in separating the photogenerated electrons and holes, which is of great importance for photocatalytic activity. • SiO{sub 2} acted as a carrier for CeO{sub 2} attachment and avoided the agglomeration of CeO{sub 2} particles. - Abstract: In this study, CeO{sub 2} photocatalyst was modified by composite with SiO{sub 2} to increase efficiency and improve photocatalytic activity. The as-prepared SiO{sub 2} particles have been incorporated into the precursor mixture of CeO{sub 2} by homogeneous precipitation and subsequent calcination process. The phase compositions of CeO{sub 2} before and after compositing with SiO{sub 2} were identified by X-ray diffraction (XRD). The morphology and particle size of CeO{sub 2}/SiO{sub 2} composite was analyzed by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The results showed SiO{sub 2} spheres with the particle size approximately 100–120 nm, and a uniform layer of CeO{sub 2} nanoparticles with a diameter of about 5–7 nm that were fully composite to the surfaces of SiO{sub 2}. The X-ray photoelectron spectroscopy (XPS) technique was carried out in order to characterize the change in valence state and composite characteristic by shifted peaks of binding energies. The photocatalytic activity was studied through the degradation of Rhodamine B in aqueous solution under visible light exposure. The highest photocatalytic efficiency of CeO{sub 2}/SiO{sub 2} composite was also obtained. To explain the high photocatalytic

  15. Enhanced visible light photocatalytic activity of copper-doped titanium oxide-zinc oxide heterojunction for methyl orange degradation

    Dorraj, Masoumeh; Alizadeh, Mahdi; Sairi, Nor Asrina; Basirun, Wan Jefrey; Goh, Boon Tong; Woi, Pei Meng; Alias, Yatimah

    2017-08-01

    A novel Cu-doped TiO2 coupled with ZnO nanoparticles (Cu-TiO2/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO2/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra and Brunauer-Emmett-Teller adsorption isotherm techniques. The Cu-TiO2/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO2 and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO2/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron-hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  16. Facile Synthesis of Uniform Zinc-blende ZnS Nanospheres with Excellent Photocatalytic Activity toward Methylene Blue Degradation

    PENG Si-Yan; YANG Liu-Sai; LV Ying-Ying; YU Le-Shu; HUANG Hai-Jin; WU Li-Dan

    2017-01-01

    Uniform and well-dispersed ZnS nanospheres have been successfully synthesized via a facile chemical route.The crystal structure,morphology,surface area and photocatalytic properties of the sample were characterized by powder X-ray diffraction (XRD),scanning electron microscopy (SEM),Brunauer-Emmett-Teller (BET) and ultraviolet-visible (UV-vis) spectrum.The results of characterizations indicate that the products are identified as mesoporous zinc-blende ZnS nanospheres with an average diameter of 200 nm,which are comprised of nanoparticles with the crystallite size of about 3.2 nm calculated by XRD.Very importantly,photocatalytic degradation of methylene blue (MB)shows that the as-prepared ZnS nanospheres exhibit excellent photocatalytic activity with nearly 100% of MB decomposed after UV-light irradiation for 25 min.The excellent photocatalytic activity of ZnS nanospheres can be ascribed to the large specific surface area and hierarchical mesoporous structure.

  17. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO{sub 4} photocatalyst

    Chala, Sinaporn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Khatcharin [Program of Physics, Faculty of Science, Ubon Ratchathani Rajabhat University, Ubon Ratchathani 34000 (Thailand); Phanichphant, Sukon [Materials Science Research Centre, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Inceesungvorn, Burapat [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Natda, E-mail: natda_we@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-06-01

    Highlights: • Fe-loaded BiVO{sub 4} particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO{sub 4} samples showed higher photocatalytic activity than pure BiVO{sub 4}. • The Fe{sup 3+} ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO{sub 4} and nominal 0.5–5.0 mol% Fe-loaded BiVO{sub 4} samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO{sub 4} shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO{sub 4}. Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO{sub 4} sample exhibited remarkably higher activity than pure BiVO{sub 4}.

  18. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO4 photocatalyst

    Chala, Sinaporn; Wetchakun, Khatcharin; Phanichphant, Sukon; Inceesungvorn, Burapat; Wetchakun, Natda

    2014-01-01

    Highlights: • Fe-loaded BiVO 4 particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO 4 samples showed higher photocatalytic activity than pure BiVO 4 . • The Fe 3+ ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO 4 and nominal 0.5–5.0 mol% Fe-loaded BiVO 4 samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO 4 shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO 4 . Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO 4 sample exhibited remarkably higher activity than pure BiVO 4

  19. Hydrothermal synthesis of fluorinated anatase TiO_2/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A

    Luo, Lijun; Yang, Ye; Zhang, Ali; Wang, Min; Liu, Yongjun; Bian, Longchun; Jiang, Fengzhi; Pan, Xuejun

    2015-01-01

    Graphical abstract: - Highlights: • F–TiO_2–RGO nanocomposites were synthesized via hydrothermal method. • Presence of F ion prevents phase transformation from anatase to rutile. • The adsorbed F"− and RGO improve the photocatalytic activity of TiO_2 synergistically. • The F–TiO_2–RGO nanocomposites were applied to degrade bisphenol A. - Abstract: The surface fluorinated TiO_2/reduced graphene oxide nanocomposites (denoted as F–TiO_2–RGO) were synthesized via hydrothermal method. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The results showed that pure anatase TiO_2 particles were anchored on the surface of reduced graphene oxide. And the HF added during the preparation process can not only prevent phase transformation from anatase to rutile, but also the F"− ion adsorbed on the surface of TiO_2–RGO surface can enhance photocatalytic activity of F–TiO_2–RGO. The photocatalytic activities of F–TiO_2–RGO nanocomposites were evaluated by decomposing bisphenol A under UV light illumination. Under optimal degradation condition, the degradation rate constant of BPA over F–TiO_2–10RGO (0.01501 min"−"1) was 3.41 times than that over P25 (0.00440 min"−"1). The result indicated that the enhanced photocatalytic activity of F–TiO_2–10RGO was ascribed to the adsorbed F ion and RGO in F–TiO_2–RGO composite, which can reduce the recombination rate of the photo-generated electrons and holes synergistically.

  20. Solar photocatalytic activity of TiO2 modified with WO3 on the degradation of an organophosphorus pesticide

    Ramos-Delgado, N.A.; Gracia-Pinilla, M.A.; Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L.; Hernández-Ramírez, A.

    2013-01-01

    Highlights: • TiO 2 and WO 3 /TiO 2 (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO 2 . • The mineralization rate was improved when WO 3 content on TiO 2 was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO 3 /TiO 2 photocatalysts synthesized by the sol–gel method with two different percentages of WO 3 (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO 2 was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA BET ), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO 3 was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO 3 /TiO 2 and 1.35 ± 0.3 nm for 5% WO 3 /TiO 2 ) and uniformly dispersed on the surface of TiO 2 . The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO 3 /TiO 2 , respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO 3 /TiO 2 photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO 3 /TiO 2 and bare TiO 2 photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO 3 /TiO 2 catalyst activity on repeated uses; after several successive cycles its photocatalytic activity was retained showing long-term stability

  1. BCT phase formation in synthesis via microwave assisted hydrothermal method

    Barra, B.C.; Souza, A.E.; Teixeira, S.R.; Santos, G.T.A.; Lanzi, C.A.C.

    2012-01-01

    In previous work, samples of barium and calcium titanate (Ba1-xCaxTiO3 (BCT x = 0- 1) were prepared using the microwave assisted hydrothermal method in conditions of relatively short time and temperature. To the sample with 75wt% of Ca no BCT phase was formed but the photoluminescent emission was improved. In the present study, these titanates were synthesized by the same method with other concentrations of Ca, Ba1-xCaxTiO3 (x = 0, 0.20, 0.40, 0. 60, 0.80 and 1) to evaluate the limit of BCT phase formation. Results of X-ray diffraction showed that the phase BCT is formed between zero and 50wt%-Ca, in Ba substitution. Above this concentration, was observed only the formation of carbonates, and to x = 1 there was carbonate formation together with CaTiO3. These results were confirmed by micro Raman spectroscopy. (author)

  2. Microwave assisted pyrolysis of halogenated plastics recovered from waste computers.

    Rosi, Luca; Bartoli, Mattia; Frediani, Marco

    2018-03-01

    Microwave Assisted Pyrolysis (MAP) of the plastic fraction of Waste from Electric and Electronic Equipment (WEEE) from end-life computers was run with different absorbers and set-ups in a multimode batch reactor. A large amount of various different liquid fractions (up to 76.6wt%) were formed together with a remarkable reduction of the solid residue (up to 14.2wt%). The liquid fractions were characterized using the following different techniques: FT-IR ATR, 1 H NMR and a quantitative GC-MS analysis. The liquid fractions showed low density and viscosity, together with a high concentration of useful chemicals such as styrene (up to 117.7mg/mL), xylenes (up to 25.6mg/mL for p-xylene) whereas halogenated compounds were absent or present in a very low amounts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Microwave assistance of labeling hippuric acid by I-131

    Sherlock Huang, Lin-Chiang; Wu, Kou-Hung; Ko, Pi-Wen; Hsieh, Cheng-Ying; Pao, Kuan-Chuan; Chou, Shih-Ching; Shieh, Fa-Kuen; Sureshbabu, Radhakrishnan; Hsu, Ming-Hua

    2014-01-01

    This work presents a novel approach for labeling hippuric acid with I-131 using microwaves. It utilizes copper(II) acetate as a catalyst of the labeling. The process involves the use of this catalytic copper(II) acetate at low dilutions that were nevertheless sufficient to produce labeled hippuric acid with high radiochemical purity in a short time. Therefore, the novel technique overcomes the limitations of previously reported conventional methods that involve heating. - Highlights: • We report the microwave assisted radiochemical labeling of hippuric acid by I-131. • Cu(OAc) 2 can be used as catalyst to get labeled product in lower dilution condition. • Advantages of our method are lesser time scale and high radiochemical purity.

  4. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Shao-Peng, Zhu; Shao-Chun, Tang; Xiang-Kang, Meng

    2009-01-01

    Silver nanoparticles with an average size of about 20 nm are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method. The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability. (cross-disciplinary physics and related areas of science and technology)

  5. Immobilized TiO2 for Phenol Degradation in a Pilot-Scale Photocatalytic Reactor

    Sylwia Mozia

    2012-01-01

    Full Text Available Phenol degradation was carried out in a photocatalytic pilot plant reactor equipped with a UV/vis mercury lamp. The total volume of treated water was equal to 1.35 m3. TiO2 P25 was used as a photocatalyst and it was immobilized on two different supports: (i a steel mesh and (ii a fiberglass cloth. Moreover, the performance of commercially available Photospheres-40 was examined. In addition, an experiment in the absence of a photocatalyst was conducted. The commercially available Photospheres-40 were found to be inadequate for the presented application due to their fragility, which in connection with vigorous mixing and pumping led to their mechanical destruction and loss of floating abilities. The highest effectiveness of phenol decomposition and mineralization was observed in the presence of TiO2 supported on the fiberglass cloth. After 15 h of the process, phenol and total organic carbon concentrations decreased by ca. 80% and 50%, respectively.

  6. Enhanced photocatalytic degradation of pollutants in petroleum refinery wastewater under mild conditions

    Saien, J.; Nejati, H.

    2007-01-01

    A circulating photocatalytic reactor was used for removing aliphatic and aromatic organic pollutants in refinery wastewater. The TiO 2 added wastewater samples, while saturating with air, were irradiated with an immersed mercury UV lamp (400 W, 200-550 nm). Optimal catalyst concentration, fluid pH and temperature were obtained at amounts of near 100 mg L -1 , 3 and 318 K, respectively. A maximum reduction in chemical oxygen demand of more than 90% was achieved after about 4 h irradiation and hence, 73% after about only 90 min; significant pollutant removal was also achievable in the other conditions. The identification of the organic pollutants, provided by means of a GC/MS and a GC analysis systems, equipped with headspace injection technique, showed that the major compounds were different fractions of petroleum aliphatic hydrocarbons (up to C 10 ) and the well-known aromatic compounds such as benzene, toluene and ethylbenzene. The results showed a high efficiency degradation of all of these pollutants

  7. Enhanced photocatalytic degradation of pollutants in petroleum refinery wastewater under mild conditions

    Saien, J. [Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan 65174 (Iran, Islamic Republic of)], E-mail: saien@basu.ac.ir; Nejati, H. [Department of Applied Chemistry, University of Bu-Ali Sina, Hamadan 65174 (Iran, Islamic Republic of)

    2007-09-05

    A circulating photocatalytic reactor was used for removing aliphatic and aromatic organic pollutants in refinery wastewater. The TiO{sub 2} added wastewater samples, while saturating with air, were irradiated with an immersed mercury UV lamp (400 W, 200-550 nm). Optimal catalyst concentration, fluid pH and temperature were obtained at amounts of near 100 mg L{sup -1}, 3 and 318 K, respectively. A maximum reduction in chemical oxygen demand of more than 90% was achieved after about 4 h irradiation and hence, 73% after about only 90 min; significant pollutant removal was also achievable in the other conditions. The identification of the organic pollutants, provided by means of a GC/MS and a GC analysis systems, equipped with headspace injection technique, showed that the major compounds were different fractions of petroleum aliphatic hydrocarbons (up to C{sub 10}) and the well-known aromatic compounds such as benzene, toluene and ethylbenzene. The results showed a high efficiency degradation of all of these pollutants.

  8. Efficient tetracycline adsorption and photocatalytic degradation of rhodamine B by uranyl coordination polymer

    Ren, Ya-Nan; Xu, Wei; Zhou, Lin-Xia; Zheng, Yue-Qing

    2017-07-01

    Two mixed uranyl-cadmium malonate coordination polymers [(UO2)2Cd(H-bipy)2(mal)4(H2O)2]·4H2O 1 and [(UO2)Cd(bipy)(mal)2]·H2O 2 (H2mal = malonic acid, bipy =4,4‧-bipyridine) have been synthesized in room temperature. Compound 1 represents a one-dimensional (1D) chain assembly of Cd(II) ions, uranyl centers and malonate ligands. Compound 2 exhibits a two-dimensional (2D) 2D +2D → 3D polycatenated framework based on inclined interlocked 2D 44 sql grids. The two compounds have been characterized by elemental analysis, IR and UV-vis spectroscopy, thermal analysis, powder X-ray diffraction and photoluminescence spectroscopy. And the ferroelectric property of 2 also has been studied. Moreover, compound 2 exhibits good photocatalytic activity for dye degradation under UV light and is excellent adsorbent for removing tetracycline antibiotics in the aqueous solution.

  9. Synthesis and photocatalytic activity of anatase TiO2 nanoparticles for degradation of methyl orange

    Singh, Manmeet; Duklan, Neha; Singh, Pritpal; Sharma, Jeewan

    2018-05-01

    In present study, TiO2 nanoparticles, in anatase form, were successfully synthesized using TiCl4 as precursor. These nanoparticles were synthesized by sol-gel method at room temperature (298 K). As prepared samples were characterized for phase structure, optical absorption and surface properties using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV-Visible spectroscopy. The synthesized TiO2 nanoparticles sample was compared with one of the most efficient commercial photocatalyst Degussa TiO2 also known as P(25). The effect of phase composition of anatase TiO2 nanoparticles, as compared to P(25), on photocatalytic decomposition of organic dye, methyl orange (MO) was studies under UV light illumination. An enhanced degradation of hazardous dye was observed in the presence of anatase TiO2 nanoparticles as compared to P(25) due to slow recombination rate. Other possible reasons for this enhancement have also been discussed.

  10. Photocatalytic degradation of bisphenol A in the presence of Ce–ZnO: Evolution of kinetics, toxicity and photodegradation mechanism

    Bechambi, Olfa [Université de Tunis El Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie des Matériaux et Catalyse, 2092, Tunis (Tunisia); Jlaiel, Lobna [Laboratoire de Bioprocédés Environnementaux, Centre de Biotechnologie de Sfax, B.P. 1177, 3018 Sfax (Tunisia); Najjar, Wahiba, E-mail: najjarwahiba2014@gmail.com [Université de Tunis El Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie des Matériaux et Catalyse, 2092, Tunis (Tunisia); Sayadi, Sami [Laboratoire de Bioprocédés Environnementaux, Centre de Biotechnologie de Sfax, B.P. 1177, 3018 Sfax (Tunisia)

    2016-04-15

    Ce–ZnO (2 mol %) and undoped ZnO catalysts have been synthesized through hydrothermal method and characterized by X-ray diffraction (XRD), Nitrogen physisorption at 77 K; Fourier transformed infrared spectroscopy (FTIR), UV–Visible spectroscopy, Photoluminescence spectra (PL), and Raman spectroscopy. Ce-doping reduces the average crystallite size, increases the BET surface area, shifts the absorption edge, reduces the electron–hole recombination and consequently improves photodegradation efficiency of Bisphenol A (BPA) in the presence of UV irradiation and hydrogen peroxide. The photocatalytic optimum conditions were established by studying the influence of various operational parameters including catalyst concentration, initial BPA concentration, H{sub 2}O{sub 2} concentration and initial pH. Under optimum conditions, Ce–ZnO (2%) achieved 100% BPA degradation and 61% BPA mineralization after 24 h of UV irradiation. BPA degradation reaction followed pseudo first-order kinetics according to the Langmuir–Hinshelwood model. Based on the identified intermediate products, the possible mechanism for BPA photodegradation is proposed. Toxicity under the optimum condition was also evaluated. - Graphical abstract: Proposed photocatalytic degradation pathway of BPA in the presence of Ce– ZnO (2%)/UV/H{sub 2}O{sub 2} system. - Highlights: • Influence of different parameters on the degradation and mineralization of BPA. • Identification of possible degradation products. • Toxicity tests conducted with Vibrio fischeri. • Simple and direct photodegradation mechanism of BPA is proposed.

  11. Degradation of amoxicillin, ampicillin and cloxacillin antibiotics in aqueous solution by the UV/ZnO photocatalytic process

    Elmolla, Emad S.; Chaudhuri, Malay

    2010-01-01

    The study examined the effect of operating conditions (zinc oxide concentration, pH and irradiation time) of the UV/ZnO photocatalytic process on degradation of amoxicillin, ampicillin and cloxacillin in aqueous solution. pH has a great effect on amoxicillin, ampicillin and cloxacillin degradation. The optimum operating conditions for complete degradation of antibiotics in an aqueous solution containing 104, 105 and 103 mg/L amoxicillin, ampicillin and cloxacillin, respectively were: zinc oxide 0.5 g/L, irradiation time 180 min and pH 11. Under optimum operating conditions, complete degradation of amoxicillin, ampicillin and cloxacillin occurred and COD and DOC removal were 23.9 and 9.7%, respectively. The photocatalytic reactions under optimum conditions approximately followed a pseudo-first order kinetics with rate constant (k) 0.018, 0.015 and 0.029 min -1 for amoxicillin, ampicillin and cloxacillin, respectively. UV/ZnO photocatalysis can be used for amoxicillin, ampicillin and cloxacillin degradation in aqueous solution.

  12. Focused-microwave-assisted sample preparation (M8)

    Nobrega, J.A.; Santos, D.M.; Trevizan, L.C.; Costa, L.M.; Nogueira, A.R.A.

    2002-01-01

    Full text: Focused-microwave-assisted sample preparation is a suitable strategy when dealing with high masses of organic samples. However, the final acid concentration of the digestate can difficult routine analytical measurements using spectroscopic techniques. Acids could be evaporated, but this step could be slow even when using microwave-assisted heating and requires a scrubber system for acid vapor collection and neutralization. We are investigating two procedures to decrease the acid concentration of digestates. The first one is based on acid vapor phase digestion of samples contained in PTFE devices' inserted into the microwave flask. The acid solution is heated by absorption of microwave radiation, then the acid vapor partially condenses in the upper part of the reaction flask and it is partially collected in each sample container. Calcium, Fe, Mg, Mn, and Zn were quantitatively recovered in samples of animal and vegetable tissues. Better recoveries were attained when adding a small volume of sodium hypochlorite to the sample. This effect is probably related to the generation of chlorine in the sample container after collecting condensed acid. The second procedure developed is based on the gradual addition of liquid samples to a previously heated acid digestion mixture. This procedure was successfully applied for digestion of milk, fruit juices, and red wine. The main advantage is the possibility of digesting up to four-fold more sample using up to ten-fold lower amounts of concentrated acids. Results obtained using both digestion procedures and measurements by ICP-OES with axial view will be presented. (author)

  13. Photocatalytic Degradation of Oil using Polyvinylidene Fluoride/Titanium Dioxide Composite Membrane for Oily Wastewater Treatment

    Rusli Ummi Nadiah

    2016-01-01

    Full Text Available Production of industrial wastewater is increasing as the oil and gas industry grows rapidly over the years. The constituents in the industrial wastewater such as organic and inorganic matters, dispersed and lubricant oil and metals which have high toxicity become the major concern to the environment and ecosystem. There are many technologies are being used for oil removal from industrial wastewater. However, there are still needs to find an effective technology to treat oily wastewater before in can be discharge safely to the environment. Membrane technology is an attractive separation technology to treat oily wastewater. The aim of this study is to fabricate polyvinylidene/titanium dioxide (PVDF/TiO2 composite membrane with further treatment using hot pressed method to enhance the adhesion between TiO2 with the membrane surfaces. In this study the structural and physical properties of fabricated membrane were conducted using X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR respectively. The photocatalytic degradation of oil was measured using UV-Vis Spectroscopy. The FTIR results confirmed that, hot pressed PVDF/TiO2 membrane TiO2 was successfully deposited onto PVDF membranes surface and XRD results shows that the XRD pattern of PVDF//TiO2 found that the crystalline structure was remained unchanged after hot pressed. Clear water was obtained after synthetic oily wastewater was exposed to visible light for at least 6 hours. In conclusion, PVDF/TiO2 composite membrane can be a potential candidate to degrade oil in oily wastewater and suggested to possess an excellent performance if perform simultaneously with membrane separation process.

  14. Kinetics of microwave assisted extraction of pectin from Balinese orange peel using Pseudo-homogeneous model

    Megawati, Wulansarie, Ria; Faiz, Merisa Bestari; Adi, Susatyo; Sammadikun, Waliyuddin

    2018-03-01

    The objective of this work was to study the homogeneous kinetics of pectin extraction of Balinese orange peel conducted using Microwave Assisted Extraction (MAE). The experimental data showed that the power increases (180 to 600 W), so that the extraction yield of pectin also increases (12.2 to 30.6 % w/w). Moreover, the extraction time is longer (10, 15, and 20 min) the yield of pectin increases (8.8, 20.2, and 40.5). At time after of 20 min (25 and 30 min), the yield starts to decrease (36.6 and 22.9). This phenomena shows pectin degradation. Therefore, pectin extraction is a series reaction, i.e. extraction and degradation. The calculation result showed that pseudo series homogeneous model can quantitatively describe the extraction kinetics. The kinetic constants can be expressed by Arrhenius equation with the frequency factors of 1.58 × 105 and 2.29 × 105 1/min, while the activation energies are 64,350 and 56,571 J/mole for extraction and degradation, respectively.

  15. Sol-gel synthesis of anatase nanopowders for efficient photocatalytic degradation of herbicide Clomazone in aqueous media

    Golubović Aleksandar

    2017-01-01

    Full Text Available TiO2 nanopowders were produced by sol-gel technique using TiCl4 as a starting material. For the preparation of crystalline anatase with developed surface area, this aqueous solution has been mixed with 0.05 M or 0.07 M (NH42SO4 solution in a temperature-controlled bath. The pH values of the suspension were 7, 8 or 9. According to the x-ray diffraction (XRD analysis the anatase crystallite sizes were about 12 nm, which coincided with the average particle size revealed by scanning electron microscopy (SEM. The Raman scattering measurements have shown the presence of a small amount of highly disordered brookite phase in addition to dominant anatase phase with similar nanostructure in all synthesized powders. BET measurements revealed that all synthesized catalysts were fully mesoporous, except the sample synthesized with 0.07 M (NH42SO4 at pH=9, which had small amount of micropores. The photocatalytic degradation of herbicide Clomazone was carried out for both the pure active substance and as the commercial product (GAMIT 4-EC under UV irradiation. The best photocatalytic efficiency was obtained for the catalyst with the largest specific surface area, confirming this parameter as crucial for enhanced photocatalytic degradation of the pure active substance and commercial product of herbicide Clomazone. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45018

  16. Photocatalytic Degradation of Chlorobenzene by TiO2 in High-Temperature and High-Pressure Water

    N. Kometani

    2008-01-01

    Full Text Available A fluidized-bed-type flow reactor available for the photocatalytic treatment of the suspension of model soil under high-temperature, high-pressure conditions was designed. An aqueous suspension containing hydrogen peroxide (H2O2 as an oxidizer and inorganic oxides as a model soil, titania (TiO2, silica (SiO2, or kaoline (Al2Si2O5(OH4 was continuously fed into the reactor with the temperature and the pressure controlled to be T=20–400∘C and P = 30 MPa, respectively. The degradation of chlorobenzene (CB in water was chosen as a model oxidation reaction. It appeared that most of the model soils are not so harmful to the SCWO treatment of CB in solutions. When the TiO2 suspension containing H2O2 was irradiated with near-UV light, the promotion of the degradation caused by photocatalytic actions of TiO2 was observed at all temperatures. Persistence of the photocatalytic activity in the oxidation reaction in high-temperature, high-pressure water would open up a possibility of the development of the hybrid process based on the combination of SCWO process and TiO2 photocatalysis for the treatment of environmental pollutants in soil and water, which are difficult to handle by conventional SCWO process or catalytic SCWO process alone.

  17. Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

    Silva, M.; Calvete, M.J.F.; Gonçalves, N.P.F.; Burrows, H.D.; Sarakha, M.; Fernandes, A.; Ribeiro, M.F.; Azenha, M.E.; Pereira, M.M.

    2012-01-01

    Highlights: ► Complete immobilization of zinc(II) phthalocyanines accomplished in Al-MCM-41. ► Efficient photodegradation of model pesticides achieved using 365 nm irradiation. ► Sodium azide experiments showed the involvement of singlet oxygen ( 1 O 2 ). - Abstract: In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV–vis spectroscopy (DRS-UV–vis), luminescence, thermogravimetric analysis (TG/DSC), N 2 adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320–460 nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc-Al-MCM-41 and ZnTTMAEOPcI-Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI-Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC–MS product characterization and mechanistic studies indicate that singlet oxygen ( 1 O 2 ), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

  18. Characterization and Computation of Yb/TiO2 and Its Photocatalytic Degradation with Benzohydroxamic Acid

    Xianping Luo

    2017-11-01

    Full Text Available Yb-doped TiO2 (Yb/TiO2 compositions were synthesized by sol-gel method, and the prepared materials were characterized by X-ray Diffraction (XRD, X-ray photoelectron spectroscopy (XPS, UV-visible diffuse-reflectance spectrum (UV-Vis DRS, transmission electron microscope (TEM and high resolution transmission electron microscope (HRTEM, energy dispersive spectrometer (EDS, and N2 adsorption. A beneficiation reagent of benzohydroxamic acid (BHA was used to test the photocatalytic activity of Yb/TiO2. The characterizations indicate that the doping of Yb could inhibit the crystal growth of TiO2, enhance the specific surface area, increase the binding energy of Ti2p, and also slightly expand the adsorption ranges to visible light. Furthermore, the computation of band structure also indicates that Yb-doped TiO2 could make the forbidden band narrower than pure anatase TiO2, which presents a red shift in the absorption spectrum. As a result of the photodegradation experiment on BHA, Yb/TiO2 (0.50% in mass sintered at 450 °C displayed the highest catalytic activity for BHA when compared with pure TiO2 or other doped Yb/TiO2 compositions, and more than 89.2% of the total organic carbon was removed after 120 min. Almost all anions, including Cl−, HCO3−, NO3−, and SO42−, inhibited the degradation of BHA by Yb/TiO2, and their inhibition effects followed the order of HCO3− > NO3− > SO42− > Cl−. Cations of Na+, K+, Ca2+, and Mg2+ displayed a slight suppressing effect due to the impact of Cl− coexisting in the solution. In addition, Yb/TiO2 maintained a high photocatalytic ability with respect to BHA after four runs. It is hypothesized that ·OH is one of the main species involved in the photodegradation of BHA, and the mutual transformation of Yb3+ and Yb2+ could promote the separation of electron-hole pairs.

  19. A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

    Srujana, Dhegam; Sailu, Chinta

    2018-04-01

    The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

  20. Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films

    Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

  1. The effect of natural iron oxide and oxalic acid on the photocatalytic degradation of isoproturon: a kinetics and analytical study.

    Boucheloukh, H; Remache, W; Parrino, F; Sehili, T; Mechakra, H

    2017-05-17

    The photocatalytic degradation of isoproturon, a persistent toxic herbicide, was investigated in the presence of natural iron oxide and oxalic acid and under UV irradiation. The influence of the relevant parameters such as the pH and the iron oxide and oxalic acid concentrations has been studied. The presence of natural iron oxide and oxalic acid in the system effectively allow the degradation of isoproturon, whereas the presence of t-butyl alcohol adversely affects the phototransformation of the target pollutant, thus indicating that an OH radical initiated the degradation mechanism. The degradation mechanism of isoproturon was investigated by means of GC-MS analysis. Oxidation of both the terminal N-(CH 3 ) 2 and isopropyl groups is the initial process leading to N-monodemethylated (NHCH 3 ), N-formyl (N(CH 3 )CHO), and CHCH 3 OH as the main intermediates. The substitution of the isopropyl group by an OH group is also observed as a side process.

  2. Hierarchical La0.7Ce0.3FeO3/halloysite nanocomposite for photocatalytic degradation of antibiotics

    Li, Xiazhang; Zhu, Wei; Yan, Xiangyu; Lu, Xiaowang; Yao, Chao; Ni, Chaoying

    2016-08-01

    The hierarchical La0.7Ce0.3FeO3/halloysite nanotubes (HNTs) composites have been successfully prepared via sol-gel method. XRD and TEM characterizations indicated that the sheet-like La0.7Ce0.3FeO3 coupled with the co-precipitated CeO2 were evenly deposited onto the surface of halloysite. The photocatalytic degradation of chlortetracycline under visible light irradiation using La0.7Ce0.3FeO3/HNTs as catalyst was evaluated by high-performance liquid chromatography, which exhibited remarkable photocatalytic activity with the removal rate up to 99 % in 90 min, due to the formation of "solid solution/co-precipitation" heterostructure as well as the excellent adsorptive capability of halloysite for antibiotics.

  3. Hierarchical La0.7Ce0.3FeO3/halloysite nanocomposite for photocatalytic degradation of antibiotics

    Li, Xiazhang; Yao, Chao; Zhu, Wei; Yan, Xiangyu; Lu, Xiaowang; Ni, Chaoying

    2016-01-01

    The hierarchical La 0.7 Ce 0.3 FeO 3 /halloysite nanotubes (HNTs) composites have been successfully prepared via sol-gel method. XRD and TEM characterizations indicated that the sheet-like La 0.7 Ce 0.3 FeO 3 coupled with the co-precipitated CeO 2 were evenly deposited onto the surface of halloysite. The photocatalytic degradation of chlortetracycline under visible light irradiation using La 0.7 Ce 0.3 FeO 3 /HNTs as catalyst was evaluated by high-performance liquid chromatography, which exhibited remarkable photocatalytic activity with the removal rate up to 99 % in 90 min, due to the formation of ''solid solution/co-precipitation'' heterostructure as well as the excellent adsorptive capability of halloysite for antibiotics. (orig.)

  4. Photocatalytic degradation of Lissamine Green B dye by using nanostructured sol–gel TiO{sub 2} films

    Ćurković, Lidija, E-mail: lcurkov@fsb.hr [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb (Croatia); Ljubas, Davor [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb (Croatia); Šegota, Suzana [Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia); Bačić, Ivana [Forensic Science Centre Ivan Vučetić, Ministry of the Interior, Ilica 335, Zagreb (Croatia)

    2014-08-01

    Highlights: • Nanostructured photocatalytic TiO{sub 2} films were prepared by sol–gel methods. • The addition of PEG to the TiO{sub 2} film changes the surface morphology and roughness parameters. • The addition of PEG to the initial sols increases photocatalytic properties of TiO{sub 2}. • LGB water solution could be decolourised within 2 h. • The influence of photolysis and adsorption on the LGB removal from the solution is negligible. - Abstract: Nanostructured sol–gel TiO{sub 2} films were prepared on a glass substrate by means of the dip-coating technique with titanium tetraisopropoxide as a precursor. TiO{sub 2} sols were synthesized with and without the addition of polyethylene glycol (PEG) as a structure-directing agent. The synthesized sol–gel TiO{sub 2} were characterized by XRD, AFM, FTIR and Micro-Raman spectroscopy. The photocatalytic activity of the films was evaluated by the photocatalytic degradation of Lissamine Green B (LGB) dye (dissolved in water) as a model pollutant with the predominant irradiation wavelength of 365 nm (UV-A). It was found that the addition of PEG to the initial sol affects the surface morphology and the photocatalytic properties of prepared sol–gel TiO{sub 2} films. AFM analysis confirmed the presence of nanostructured sol–gel titania films on the glass substrate. Roughness parameters (R{sub a}, R{sub q}, and Z{sub max}) of the sol–gel TiO{sub 2} film with the addition of PEG are higher than the parameters of the sol–gel TiO{sub 2} film without the addition of PEG. The TiO{sub 2} film prepared with the addition of PEG has a higher surface density (a larger active surface area) and better photocatalytic activity in the degradation of the LGB dye solution than the TiO{sub 2} film prepared without the addition of PEG.

  5. Photocatalytic performance of Sn-doped TiO2 nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights

    Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

    2008-01-01

    Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO 2 based thin films, contain at different solid ratio of TiO 2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

  6. Preparation of Ag–AgBr/TiO2–graphene and its visible light photocatalytic activity enhancement for the degradation of polyacrylamide

    Rong, Xinshan; Qiu, Fengxian; Zhang, Chen; Fu, Liang; Wang, Yuanyuan; Yang, Dongya

    2015-01-01

    Highlights: • Ag–AgBr/TiO 2 –graphene (AATG) composite photocatalyst was prepared. • AATG was applied to photocatalytic degradation of polyacrylamide (PAM). • Degradation condition such as mass ratio of TiO 2 /graphene, dose, pH and time, was investigated. • The AATG composite photocatalyst can be separated from system effectively and easily. • The prepared AATG exhibits significant photocatalytic activity after five successive recycles. - Abstract: In current work, TiO 2 was modified by Ag/AgBr semiconductor and graphene to enhance its photocatalytic activity for the degradation of polyacrylamide (PAM). Ag–AgBr/TiO 2 –graphene (AATG) composite photocatalysts were prepared by the deposition–precipitation method combining a subsequent calcination process. The structure, surface morphology and chemical composition of AATG composite photocatalysts were investigated by XRD, XPS, DRS, PL, SEM, EDS, TEM, and HRTEM methods. XRD and XPS results show that Ag 0 is generated from Ag + under visible light irradiation. Degradation of PAM was chosen to evaluate photocatalytic activity using AATG composite as photocatalysts. The conditions such as mass ratio of TiO 2 /graphene, catalyst dose, pH and contact time, were investigated for the degradation of PAM. Possible pathway and mechanism were proposed for photocatalytic degradation of PAM over AATG composite photocatalyst under visible light irradiation. The prepared AATG composite photocatalyst can be separated from system effectively and easily; and exhibits significant photocatalytic activity after five successive recycles, which confirmed that the components of the AATG are not photo decomposed and the structure is stable during the photocatalytic process

  7. Enhanced Visible Light Photocatalytic Degradation of Organic Pollutants over Flower-Like Bi2O2CO3 Dotted with Ag@AgBr

    Shuanglong Lin

    2016-10-01

    Full Text Available A facile and feasible oil-in-water self-assembly approach was developed to synthesize flower-like Ag@AgBr/Bi2O2CO3 micro-composites. The photocatalytic activities of the samples were evaluated through methylene blue degradation under visible light irradiation. Compared to Bi2O2CO3, flower-like Ag@AgBr/Bi2O2CO3 micro-composites show enhanced photocatalytic activities. In addition, results indicate that both the physicochemical properties and associated photocatalytic activities of Ag@AgBr/Bi2O2CO3 composites are shown to be dependent on the loading quantity of Ag@AgBr. The highest photocatalytic performance was achieved at 7 wt % Ag@AgBr, degrading 95.18% methylene blue (MB after 20 min of irradiation, which is over 1.52 and 3.56 times more efficient than that of pure Ag@AgBr and pure Bi2O2CO3, respectively. Bisphenol A (BPA was also degraded to further demonstrate the degradation ability of Ag@AgBr/Bi2O2CO3. A photocatalytic mechanism for the degradation of organic compounds over Ag@AgBr/Bi2O2CO3 was proposed. Results from this study illustrate an entirely new approach to fabricate semiconductor composites containing Ag@AgX/bismuth (X = a halogen.

  8. Synthesis of Cu/TiO{sub 2}/organo-attapulgite fiber nanocomposite and its photocatalytic activity for degradation of acetone in air

    Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn; Wang, He; Guo, Sheng; Wang, Junting; Liu, Jin

    2016-01-30

    Graphical abstract: - Highlights: • A novel Cu/TiO{sub 2}/organo-attapulgite fiber nanocomposite was synthesized successfully. • Micro-mesopore nanocomposite structure was in favor of the degradation of acetone. • CTAB modification improved the adsorption capability of the catalyst. • The photocatalytic degradation mechanism of the acetone by the catalyst was studied. - Abstract: The Cu/TiO{sub 2}/organo-attapulgite fiber (CTOA) nanocomposite was synthesized by a facile method and was used for photocatalytic degradation of acetone in air under UV light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectrum (UV–vis DRS), inductively coupled plasma (ICP) spectrometry and N{sub 2} adsorption–desorption measurement. The results showed that the structure of organo-attapulgite (OAT) had no obvious change as compared to unmodified attapulgite (AT) and the attapulgite fibers in the OAT were well-dispersed. Both micropores and mesopores exist in the CTOA catalyst. The CTOA catalysts prepared at the Cu/TiO{sub 2} molar ratio of 0.003 shows an excellent photocatalytic activity for the degradation of acetone in air. The synergistic effect of Cu species and cetyltrimethylammonium bromide modification can be responsible for the enhanced photocatalytic activity of the CTOA catalyst. The mechanism of the photocatalytic degradation of acetone by the CTOA catalyst was discussed.

  9. A facile synthesis of ZnWO{sub 4} nanoparticles by microwave assisted technique and its application in photocatalysis

    Garadkar, K.M., E-mail: kmg_chem@unishivaji.ac.in [Nanomaterials Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur 416 004, MS (India); Ghule, L.A. [Nanomaterials Research Laboratory, Department of Chemistry, Shivaji University, Kolhapur 416 004, MS (India); Sapnar, K.B.; Dhole, S.D. [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune 411 007, MS (India)

    2013-03-15

    Highlights: ► Nanocrystalline ZnWO{sub 4} particles were successfully prepared by a microwave method. ► Spherical morphology with a 10 nm size. ► The band is 3.4 eV. ► The photodegradation of RhB was 95% within 25 min. - Abstract: A simple microwave assisted technique has been successfully developed to synthesize ZnWO{sub 4} nanoparticles. The X-ray diffraction results indicated that the synthesized nanoparticles exhibited only wolframite structure. Structural, morphological and optical properties of ZnWO{sub 4} nanoparticles have been analyzed by XRD, SEM, TEM EDAX, UV–vis and FT-IR spectral measurements. The transmission electron microscopy (TEM) image revealed that particle size of ZnWO{sub 4} nanoparticles was found to be 10 nm, the band-gap of ZnWO{sub 4} nanoparticles was found to be 3.4 eV. The photocatalytic activities for aqueous Rhodamine B and Methylene Blue samples were investigated and observed that ZnWO{sub 4} nanoparticles exhibited highly enhanced photocatalytic activity towards RhB than MB.

  10. One-step microwave-assisted colloidal synthesis of hybrid silver oxide/silver nanoparticles: characterization and catalytic study

    Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    This study reports the characterization and catalytic activities of silver-oxide/silver nanoparticles (Ag2O/Ag NPs) synthesized by microwave-assisted colloidal method in the presence of anionic sodium dodecyl sulfate (SDS) surfactant. To promote different contents of silver in silver oxide, the volume ratio (VR) of ethylene glycol (EG) was varied (VR: 10% to 14%) in relation to the total volume of distilled water solvent. The plasmonic resonance of Ag2O/Ag NPs could be detected around a wavelength of 350 nm, and it is suggested that Ag2O/Ag NPs were successfully formed in the colloid solution following exposure to microwaves. Additionally, the growth rate for each crystal phase within Ag2O and Ag was influenced by an increase of EG as revealed by x-ray diffraction patterns. The morphology, average diameter, and uniformity of Ag2O/Ag NPs were studied simultaneously by transmission electron microscopy. Infrared absorption measurement of Ag2O/Ag NPs confirmed the existence of SDS surfactant as a protective agent. Based on the characterization data, Ag2O/Ag NPs synthesized using this technique exhibited good properties, with high-yield production of NPs. The photocatalytic experiments demonstrate the key role of the crystal phase of Ag2O/Ag NPs in photocatalytic efficiency.

  11. Synergetic effect of Ag_2O as co-catalyst for enhanced photocatalytic degradation of phenol on N-TiO_2

    Chu, Haipeng; Liu, Xinjuan; Liu, Junying; Li, Jinliang; Wu, Tianyang; Li, Haokun; Lei, Wenyan; Xu, Yan; Pan, Likun

    2016-01-01

    Graphical abstract: Ag_2O/N-TiO_2 composites were synthesized via a co-precipitation method for visible light photocatalytic degradation of organic pollutions with excellent photocatalytic activity. - Highlights: • Ag_2O/N-TiO_2 composites were synthesized via a facile precipitation method. • Ag_2O/N-TiO_2 composites exhibited enhanced photocatalytic activity. • Ag_2O acts as co-catalyst to separate the photo-generated electron-hole pairs. - Abstract: A facile precipitation method was developed to synthesize the Ag_2O/N-TiO_2 composites. Their morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) and phenol under visible light irradiation were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence spectroscopy and UV–vis absorption spectroscopy, respectively. The results show that the Ag_2O/N-TiO_2 composites exhibit excellent photocatalytic performance. The maximum degradation rates of MB and phenol are about 8.9 and 2.9 times that of pure N-TiO_2, respectively. The excellent photocatalytic performance is mainly ascribed to the synergetic effects of Ag_2O and N-TiO_2 including the increased light absorption and the reduced electron-hole pair recombination in N-TiO_2 with the presence of Ag_2O.

  12. Production of xylooligosaccharide from wheat bran by microwave assisted enzymatic hydrolysis.

    Wang, Tseng-Hsing; Lu, Shin

    2013-06-01

    The effective production of xylooligosaccharides (XOS) from wheat bran was investigated. Wheat bran contains rich hemicellulose which can be hydrolyzed by enzyme; the XOS were obtained by microwave assisted enzymatic hydrolysis. To improve the productivity of XOS, repeated microwave assisted enzymatic hydrolysis and activated carbon adsorption method was chosen to eliminate macromolecules in the XOS. On the basis of experimental data, an industrial XOS production process consisting of pretreatment, repeated microwave assisted enzymatic treatment and purification was designed. Using the designed process, 3.2g dry of purified XOS was produced from 50 g dry wheat bran powder. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Attapulgite-CeO2/MoS2 ternary nanocomposite for photocatalytic oxidative desulfurization

    Li, Xiazhang; Zhang, Zuosong; Yao, Chao; Lu, Xiaowang; Zhao, Xiaobing; Ni, Chaoying

    2016-02-01

    Novel attapulgite(ATP)-CeO2/MoS2 ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV-vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO2/MoS2 composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO2 to MoS2 on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO2 particles and MoS2 nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO2/MoS2 is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

  14. CaSnO 3 obtained by modified Pechini method applied in the photocatalytic degradation of an azo dye

    G. L. Lucena

    Full Text Available Abstract Pure forms of alkaline-earth stannates with perovskite structure (ASnO3, A= Ca2+, Sr2+, Ba2+ have been used as photocatalysts. In this work, CaSnO3 perovskite sample was synthesized by a modified Pechini method at 800 ºC and characterized by X-ray diffraction (XRD, UV-visible spectroscopy, infrared spectroscopy and Raman spectroscopy. The photocatalytic degradation of remazol golden yellow (RNL dye under UV radiation was evaluated. The XRD pattern showed that the synthesis method favored the orthorhombic CaSnO3 crystallization. According to the Raman spectrum, a material with high short-range order was obtained despite of the relatively low synthesis temperature, compared to the solid-state reaction one. The highest photocatalytic activity was attained at pH 3, which presented 51% discoloration and improved activity of 35% compared to discoloration solely due to adsorption (absence of radiation. The point of zero charge (PZC and the photocatalytic results indicated that a direct mechanism prevailed at pH 3, whereas an indirect mechanism prevailed at pH 6.

  15. Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

    SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

    2007-01-01

    Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

  16. The Promoting Role of Different Carbon Allotropes Cocatalysts for Semiconductors in Photocatalytic Energy Generation and Pollutants Degradation

    Weiwei Han

    2017-10-01

    Full Text Available Semiconductor based photocatalytic process is of great potential for solving the fossil fuels depletion and environmental pollution. Loading cocatalysts for the modification of semiconductors could increase the separation efficiency of the photogenerated hole-electron pairs, enhance the light absorption ability of semiconductors, and thus obtain new composite photocatalysts with high activities. Kinds of carbon allotropes, such as activated carbon, carbon nanotubes, graphene, and carbon quantum dots have been used as effective cocatalysts to enhance the photocatalytic activities of semiconductors, making them widely used for photocatalytic energy generation, and pollutants degradation. This review focuses on the loading of different carbon allotropes as cocatalysts in photocatalysis, and summarizes the recent progress of carbon materials based photocatalysts, including their synthesis methods, the typical applications, and the activity enhancement mechanism. Moreover, the cocatalytic effect among these carbon cocatalysts is also compared for different applications. We believe that our work can provide enriched information to harvest the excellent special properties of carbon materials as a platform to develop more efficient photocatalysts for solar energy utilization.

  17. Photocatalytic degradation of C. I. Reactive Red 24 solution with K₆SiW₁₁O₃₉Sn(II.).

    Guo, Guixiang; Zhu, Xiuhua; Shi, Fuyou; Wang, Anning; Wang, Wei; Mu, Jun; Wan, Quanli; Zhang, Rong

    2013-12-01

    Environmental friendly materials, K6SiW11O39Sn (SiWSn), was synthesized. SiWSn photocatalytic decomposition of C. I. Reactive Red 24 (RR24) with the UV-lamp (253.7 nm, 20 W), Xenon lamp filtered less than 390 nm light (500 W) and sun light was investigated. The results showed that RR24 solution could be effectively decolorized with the SiWSn photocatalyst. The photocatalytic degradation efficiency of RR24 with SiWSn was affected by the initial concentration of RR2 solution, the amount of SiWSn and the photolysis time. It is demonstrated that the process of photodegradation of RR24 with SiWSn is a pesudo first-order reaction, which can be described by Langmuir-Hinshelwood equation. Hydroxyl radicals and holes are both the main oxidants in the photocatalytic reaction of RR24 with SiWSn. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  18. Photocatalytic degradation of Reactive Black 5 and Malachite Green with ZnO and lanthanum doped nanoparticles

    Kaneva, N; Bojinova, A; Papazova, K

    2016-01-01

    Here we report the preparation of ZnO particles with different concentrations of La 3 + doping (0, 0.5 and 1 wt%) via sol-gel method. The nanoparticles are synthesized directly from Zn(CH 3 COO) 2 .2H 2 O in the presence of 1-propanol and triethylamine at 80°C. The conditions are optimized to obtain particles of uniform size, easy to isolate and purify. The nanoparticles are characterized by SEM, XRD and UV-Vis analysis. The photocatalytic properties of pure and La-doped ZnO are studied in the photobleaching of Malachite Green (MG) and Reactive Black 5 (RB5) dyes in aqueous solutions upon UV illumination. It is observed that the rate constant increases with the La loading up to 1 wt%. The doping helps to achieve complete mineralization of MG within a short irradiation time. 1 wt% La-doped ZnO nanoparticles show highest photocatalytic activity. The La 3+ doped ZnO particles degrade faster RB5 than MG. The reason is weaker N=N bond in comparison with the C-C bond between the central carbon atom and N,N-dimethylaminobenzyl in MG. The as-prepared ZnO particles can find practical application in photocatalytic purification of textile wastewaters. (paper)

  19. Modulation of defect-mediated energy transfer from ZnO nanoparticles for the photocatalytic degradation of bilirubin

    Tanujjal Bora

    2013-11-01

    Full Text Available In recent years, nanotechnology has gained significant interest for applications in the medical field. In this regard, a utilization of the ZnO nanoparticles for the efficient degradation of bilirubin (BR through photocatalysis was explored. BR is a water insoluble byproduct of the heme catabolism that can cause jaundice when its excretion is impaired. The photocatalytic degradation of BR activated by ZnO nanoparticles through a non-radiative energy transfer pathway can be influenced by the surface defect-states (mainly the oxygen vacancies of the catalyst nanoparticles. These were modulated by applying a simple annealing in an oxygen-rich atmosphere. The mechanism of the energy transfer process between the ZnO nanoparticles and the BR molecules adsorbed at the surface was studied by using steady-state and picosecond-resolved fluorescence spectroscopy. A correlation of photocatalytic degradation and time-correlated single photon counting studies revealed that the defect-engineered ZnO nanoparticles that were obtained through post-annealing treatments led to an efficient decomposition of BR molecules that was enabled by Förster resonance energy transfer.

  20. Immobilized/P25/DSAT and Immobilized/Kronos/DSAT on Photocatalytic Degradation of Reactive Red 4 Under Fluorescent Light

    Azami M. S.

    2016-01-01

    Full Text Available In this work, photocatalytic degradation of Reactive Red 4 (RR4 using immobilized P25 and kronos were performed under fluorescent light sources. The photocatalysis activity for both catalysts was investigated under fluorescent lamp source which consist UV and Visible light. The effect of various parameters such as initial concentration, initial pH and strenght of immobilized plate were studied. The result showed that 90% of RR4 dye was degrade in 1 hr using immobilized/kronos/DSAT at 100 mg L-1 of RR4 dye while 81% degradation was achieved by immobilized/P25/DSAT at the same condition. The lowest pH showed the higher photocatalytic activity. Hence, the effect of dye concentration and pH on the photocatalysis study can be related with the behavior of environmental pollution. The low strength showed by immobilized/P25/DSAT where it remain 37 % as compared with strength of immobilized/kronos/DSAT (52 wt.%. For the future work, the polymer binder like Polyvinyl alcohol (PVA, Polyethylene glycol (PEG, and others polymers can be apply in immobilized study to overcome the strength problem.

  1. Synthesis and characterization of CdS/CuAl2O4 core-shell: application to photocatalytic eosin degradation

    Bellal, B.; Trari, M.; Afalfiz, A.

    2015-08-01

    The advantages of the hetero-junction CdS/CuAl2O4 for the photocatalytic eosin degradation are reported. Composite semiconductors are elaborated by co-precipitation of CdS on the spinel CuAl2O4 giving a core-shell structure with a uniform dispersion and intimate contact of the spinel nanoparticles inside the hexagonal CdS. The Mott-Schottky plots ( C -2- V) of both materials show linear behaviors from which flat band potentials are determined. The photoactivity increases with increasing the mass of the sensitizer CdS and the best performance is achieved on CdS/CuAl2O4 (85 %/15 %). The pH has a strong influence on the degradation and the photoactivity peaks at pH 7.78. The dark adsorption eosin is weak (~4 %), hence the change in the eosin concentration is attributed to the photocatalytic process. The degradation follows a zero-order kinetic with a rate constant of 5.2 × 10-8 mol L-1 mn-1 while that of the photolysis is seven times lower (0.75 × 10-8 mol L-1 mn-1).

  2. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Hu, Longxing, E-mail: hulxhhhb@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Deng, Guihua [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Lu, Wencong [College of Sciences, Shanghai University, Shanghai 200444 (China); Pang, Siwei; Hu, Xing [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2017-07-15

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB{sub aq}-visible light system was O{sub 2}{sup −}·; nevertheless, h{sup +} and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs

  3. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-01-01

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB aq -visible light system was O 2 − ·; nevertheless, h + and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the

  4. Application of Ni-Oxide@TiO₂ Core-Shell Structures to Photocatalytic Mixed Dye Degradation, CO Oxidation, and Supercapacitors.

    Lee, Seungwon; Lee, Jisuk; Nam, Kyusuk; Shin, Weon Gyu; Sohn, Youngku

    2016-12-20

    Performing diverse application tests on synthesized metal oxides is critical for identifying suitable application areas based on the material performances. In the present study, Ni-oxide@TiO₂ core-shell materials were synthesized and applied to photocatalytic mixed dye (methyl orange + rhodamine + methylene blue) degradation under ultraviolet (UV) and visible lights, CO oxidation, and supercapacitors. Their physicochemical properties were examined by field-emission scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and UV-visible absorption spectroscopy. It was shown that their performances were highly dependent on the morphology, thermal treatment procedure, and TiO₂ overlayer coating.

  5. Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

    Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

    2018-06-01

    We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

  6. Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

    Li, Xiaojuan; Jin, Bo; Huang, Jingwen; Zhang, Qingchun; Peng, Rufang; Chu, Shijin

    2018-06-01

    In this study, novel ternary Fe2O3/ZnO/ZnFe2O4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.

  7. Carbamazepine degradation using a N-doped TiO_2 coated photocatalytic membrane reactor: Influence of physical parameters

    Horovitz, Inna; Avisar, Dror; Baker, Mark A.; Grilli, Rossana; Lozzi, Luca; Di Camillo, Daniela; Mamane, Hadas

    2016-01-01

    Highlights: • UV–vis N-doped TiO_2 was deposited by sol-gel onto Al_2O_3 microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al_2O_3 membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO_2 vs. non-doped TiO_2 membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al_2O_3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO_2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO_2 films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO_2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO_2-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

  8. Carbamazepine degradation using a N-doped TiO{sub 2} coated photocatalytic membrane reactor: Influence of physical parameters

    Horovitz, Inna [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Avisar, Dror [The Hydro-Chemistry Laboratory, Faculty of Geography and the Environment, Tel Aviv University, Tel Aviv 69978 (Israel); Baker, Mark A.; Grilli, Rossana [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Lozzi, Luca; Di Camillo, Daniela [Department of Physical and Chemical Sciences, University of L' Aquila, Via Vetoio, I-67100 L' Aquila (Italy); Mamane, Hadas, E-mail: hadasmg@post.tau.ac.il [School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

    2016-06-05

    Highlights: • UV–vis N-doped TiO{sub 2} was deposited by sol-gel onto Al{sub 2}O{sub 3} microfiltration membranes. • Coating decreased permeability by 50 and 12% for 200- and 800-nm Al{sub 2}O{sub 3} membranes. • Flow through membrane results in higher reaction rates compared to flow on top. • Higher vis photocatalytic activity for N-doped TiO{sub 2} vs. non-doped TiO{sub 2} membranes. • Mass transfer is a critical parameter for the design of immobilized PMR. - Abstract: Commercial α-Al{sub 2}O{sub 3} photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO{sub 2} photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO{sub 2} films are in the form of anatase with 78–84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3–0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO{sub 2}-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO{sub 2}-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration.

  9. Microwave-Assisted Drying for the Conservation of Honeybee Pollen

    Angelo Canale

    2016-05-01

    Full Text Available Bee pollen is becoming an important product thanks to its nutritional properties, including a high content of bioactive compounds such as essential amino acids, antioxidants, and vitamins. Fresh bee pollen has a high water content (15%–30% wt %, thus it is a good substrate for microorganisms. Traditional conservation methods include drying in a hot air chamber and/or freezing. These techniques may significantly affect the pollen organoleptic properties and its content of bioactive compounds. Here, a new conservation method, microwave drying, is introduced and investigated. The method implies irradiating the fresh pollen with microwaves under vacuum, in order to reduce the water content without reaching temperatures capable of thermally deteriorating important bioactive compounds. The method was evaluated by taking into account the nutritional properties after the treatment. The analyzed parameters were phenols, flavonoids, with special reference to rutin content, and amino acids. Results showed that microwave drying offers important advantages for the conservation of bee pollen. Irrespective of microwave power and treatment time, phenol and flavonoid content did not vary over untreated fresh pollen. Similarly, rutin content was unaffected by the microwave drying, suggesting that the microwave-assisted drying could be a powerful technology to preserve bioprotective compounds in fresh pollen.

  10. Microwave-Assisted Extraction for Microalgae: From Biofuels to Biorefinery

    Rahul Vijay Kapoore

    2018-02-01

    Full Text Available The commercial reality of bioactive compounds and oil production from microalgal species is constrained by the high cost of production. Downstream processing, which includes harvesting and extraction, can account for 70–80% of the total cost of production. Consequently, from an economic perspective extraction technologies need to be improved. Microalgal cells are difficult to disrupt due to polymers within their cell wall such as algaenan and sporopollenin. Consequently, solvents and disruption devices are required to obtain products of interest from within the cells. Conventional techniques used for cell disruption and extraction are expensive and are often hindered by low efficiencies. Microwave-assisted extraction offers a possibility for extraction of biochemical components including lipids, pigments, carbohydrates, vitamins and proteins, individually and as part of a biorefinery. Microwave technology has advanced since its use in the 1970s. It can cut down working times and result in higher yields and purity of products. In this review, the ability and challenges in using microwave technology are discussed for the extraction of bioactive products individually and as part of a biorefinery approach.

  11. Microwave-assisted hydrothermal synthesis of biocompatible silver sulfide nanoworms

    Xing, Ruimin; Liu, Shanhu; Tian, Shufang

    2011-10-01

    In this study, silver sulfide nanoworms were prepared via a rapid microwave-assisted hydrothermal method by reacting silver nitrate and thioacetamide in the aqueous solution of the Bovine Serum Albumin (BSA) protein. The morphology, composition, and crystallinity of the nanoworms were characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The results show that the nanoworms were assembled by multiple adjacent Ag2S nanoparticles and stabilized by a layer of BSA attached to their surface. The nanoworms have the sizes of about 50 nm in diameter and hundreds of nanometers in length. The analyses of high-resolution TEM and their correlative Fast Fourier Transform (FFT) indicate that the adjacent Ag2S nanoparticles grow by misoriented attachment at the connective interfaces to form the nanoworm structure. In vitro assays on the human cervical cancer cell line HeLa show that the nanoworms exhibit good biocompatibility due to the presence of BSA coating. This combination of features makes the nanoworms attractive and promising building blocks for advanced materials and devices.

  12. Spin torque oscillator for microwave assisted magnetization reversal

    Taniguchi, Tomohiro; Kubota, Hitoshi

    2018-05-01

    A theoretical study is given for the self-oscillation excited in a spin torque oscillator (STO) consisting of an in-plane magnetized free layer and a perpendicularly magnetized pinned layer in the presence of a perpendicular magnetic field. This type of STO is a potential candidate for a microwave source of microwave assisted magnetization reversal (MAMR). It is, however, found that the self-oscillation applicable to MAMR disappears when the perpendicular field is larger than a critical value, which is much smaller than a demagnetization field. This result provides a condition that the reversal field of a magnetic recording bit by MAMR in nanopillar structure should be smaller than the critical value. The analytical formulas of currents determining the critical field are obtained, which indicate that a material with a small damping is not preferable to acheive a wide range of the self-oscillation applicable to MAMR, although such a material is preferable from the viewpoint of the reduction of the power consumption.

  13. Microwave-assisted extraction of lipid from fish waste

    Rahimi, M. A.; Omar, R.; Ethaib, S.; Siti Mazlina, M. K.; Awang Biak, D. R.; Nor Aisyah, R.

    2017-06-01

    Processing fish waste for extraction of value added products such as protein, lipid, gelatin, amino acids, collagen and oil has become one of the most intriguing researches due to its valuable properties. In this study the extraction of lipid from sardine fish waste was carried out using microwave-assisted extraction (MAE) and compared with Soxhlets and Hara and Radin methods. A mixture of two organic solvents isopropanol/hexane and distilled water were used for MAE and Hara and Radin methods. Meanwhile, Soxhlet method utilized only hexane as solvent. The results show that the higher yield of lipid 80.5 mg/g was achieved using distilled water in MAE method at 10 min extraction time. Soxhlet extraction method only produced 46.6 mg/g of lipid after 4 hours of extraction time. Lowest yield of lipid was found at 15.8 mg/g using Hara and Radin method. Based on aforementioned results, it can be concluded MAE method is superior compared to the Soxhlet and Hara and Radin methods which make it an attractive route to extract lipid from fish waste.

  14. Simplified polymer characterization after microwave assisted sample preparation (T9)

    Lafer, M.; Kettisch, P.; Gfrerrer, M.

    2002-01-01

    Full text: Beside the determination of fillers and heavy metals in polymers after decomposition more often stabilizers, fire inhibitors and antistatic additive agents are measured alter using fast microwave accelerated solvent extraction. Determination of heavy metal traces for example in food packaging materials needs high sample weight to detect small amounts of impurities. High sample weight is also needed for plastic waste providing the homogeneity for representative analysis. Due to the high concentration of' organic carbon and the fact that the materials swim on the acid surface, closed vessel digestion had limits concerning sample weight. A new vessel insert in combination with extremely fast reaction control allows now to double or triple usual sample weights. High performance vessels can also be used to decompose polymers filled with TiO 2 , talcum, fibers or similar within short one or two step procedures gaining solutions without precipitates. Additional filtration or sample treatment is not necessary. For the determination of organic components more and more classical, but time consuming methods are replaced by microwave assisted solvent extraction. Instead of hours or even half days using Soxhlet extraction samples can be extracted within minutes using vessels and rotors similar to those used for decomposition. The dual use of one basic microwave instrument for both, analysis of inorganic as well as organic parameters will help to increase efficiency by reduced costs. (author)

  15. Microwave-Assisted Hydrothermal Synthesis of Cellulose/Hydroxyapatite Nanocomposites

    Lian-Hua Fu

    2016-09-01

    Full Text Available In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH2PO4·2H2O, or organic phosphorus sources (adenosine 5′-triphosphate disodium salt (ATP, creatine phosphate disodium salt tetrahydrate (CP, or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH2PO4·2H2O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

  16. Fast microwave assisted pyrolysis of biomass using microwave absorbent.

    Borges, Fernanda Cabral; Du, Zhenyi; Xie, Qinglong; Trierweiler, Jorge Otávio; Cheng, Yanling; Wan, Yiqin; Liu, Yuhuan; Zhu, Rongbi; Lin, Xiangyang; Chen, Paul; Ruan, Roger

    2014-03-01

    A novel concept of fast microwave assisted pyrolysis (fMAP) in the presence of microwave absorbents was presented and examined. Wood sawdust and corn stover were pyrolyzed by means of microwave heating and silicon carbide (SiC) as microwave absorbent. The bio-oil was characterized, and the effects of temperature, feedstock loading, particle sizes, and vacuum degree were analyzed. For wood sawdust, a temperature of 480°C, 50 grit SiC, with 2g/min of biomass feeding, were the optimal conditions, with a maximum bio-oil yield of 65 wt.%. For corn stover, temperatures ranging from 490°C to 560°C, biomass particle sizes from 0.9mm to 1.9mm, and vacuum degree lower than 100mmHg obtained a maximum bio-oil yield of 64 wt.%. This study shows that the use of microwave absorbents for fMAP is feasible and a promising technology to improve the practical values and commercial application outlook of microwave based pyrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Microwave-assisted synthesis of high-loading, highly dispersed Pt ...

    Keywords. Direct methanol fuel cell; carbon aerogel; Pt; microwave-assisted polyol process; electrocatalyst; ... obtained from the carbonization of the dried organic aero- gel in a ... 12 hours. The dried residue (0·01 g) was mixed with ethanol.

  18. An easy two-step microwave assisted synthesis of SnO2/CNT hybrids

    Motshekga, SC

    2011-11-01

    Full Text Available Tin oxide (SnO2) - decorated carbon nanotube (CNT) heterostructures were synthesized by microwave assisted wet impregnation method. CNTs of three different aspect ratios were compared. The hybrid samples were characterized by powder X...

  19. Microwave-assisted silica-promoted solvent-free synthesis of ...

    method using microwave irradiation with an excellent yield. The newly ... Table 1. Silica promoted microwave-assisted solvent-free synthesis of quinazolinone ... Time (min). Yield (%)a ..... thanks SC/ST cell of Bangalore University for research.

  20. Photocatalytic degradation of an azo-dye on TiO2/activated carbon composite material.

    Andriantsiferana, C; Mohamed, E F; Delmas, H

    2014-01-01

    A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites.

  1. Enhanced photocatalytic performance of CeO2-TiO2 nanocomposite for degradation of crystal violet dye and industrial waste effluent

    Zahoor, Mehvish; Arshad, Amara; Khan, Yaqoob; Iqbal, Mazhar; Bajwa, Sadia Zafar; Soomro, Razium Ali; Ahmad, Ishaq; Butt, Faheem K.; Iqbal, M. Zubair; Wu, Aiguo; Khan, Waheed S.

    2018-03-01

    This study presents the synthesis of CeO2-TiO2 nanocomposite and its potential application for the visible light-driven photocatalytic degradation of model crystal violet dye as well as real industrial waste water. The ceria-titania (CeO2-TiO2) nanocomposite material was synthesised using facile hydrothermal route without the assistance of any template molecule. As-prepared composite was characterised by SEM, TEM, HRTEM, XRD, XPS for surface features, morphological and crystalline characters. The formed nanostructures were determined to possess crystal-like geometrical shape and average size less than 100 nm. The as-synthesised nanocomposite was further investigated for their heterogeneous photocatalytic potential against the oxidative degradation of CV dye taken as model pollutant. The photo-catalytic performance of the as-synthesised material was evaluated both under ultra-violet as well as visible light. Best photocatalytic performance was achieved under visible light with complete degradation (100%) exhibited within 60 min of irradiation time. The kinetics of the photocatalytic process were also considered and the reaction rate constant for CeO2-TiO2 nanocomposite was determined to be 0.0125 and 0.0662 min-1 for ultra-violet and visible region, respectively. In addition, the as-synthesised nanocomposite demonstrated promising results when considered for the photo-catalytic degradation of coloured industrial waste water collected from local textile industry situated in Faisalabad region of Pakistan. Enhanced photo-catalytic performance of CeO2-TiO2 nanocomposite was proposed owing to heterostructure formation leading to reduced electron-hole recombination.

  2. Photocatalytic degradation of NOx gases using TiO2-containing paint: a real scale study.

    Maggos, Th; Bartzis, J G; Liakou, M; Gobin, C

    2007-07-31

    An indoor car park was appropriately equipped in order to test the de-polluting efficiency of a TiO(2)-containing paint in an indoor polluted environment, under real scale configuration. Depollution tests were performed in an artificially closed area of the parking, which was polluted by a car exhaust during the testing period. The ceiling surface of the car park was covered with white acrylic TiO(2)-containing paint (PP), which was developed in the frame of the EU project 'PICADA' (Photocatalytic Innovative Coverings Application for Depollution Assessment). The closed area was fed with car exhaust gases. As soon as the system reached steady state, the UV lamps were turned on for 5h. The difference between the final and the initial steady state concentration indicates the removal of the pollutants due to both the photocatalytic paint and car emission reduction. Results showed a significant photocatalytic oxidation of NO(x) gases. The photocatalytic removal of NO and NO(2) was calculated to 19% and 20%, respectively, while the photocatalytic rate (microgm(-2)s(-1)) ranged between 0.05 and 0.13 for NO and between 0.09 and 0.16 for NO(2).

  3. Adsorption and photocatalytic degradation of pharmaceuticals by BiOCl{sub x}I{sub y} nanospheres in aqueous solution

    Wang, Xiaoning; Bi, Wenlong; Zhai, Pingping [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China); Wang, Xiaobing [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF)-ENSCCF, BP 10448, F-63000 Clermont-Ferrand (France); Li, Hongjing, E-mail: lihongjing@fudan.edu.cn [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China); Mailhot, Gilles [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF)-ENSCCF, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Dong, Wenbo, E-mail: wbdong@fudan.edu.cn [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China)

    2016-01-01

    Graphical abstract: - Highlights: • BiOCl{sub x}I{sub y} nanospheres were synthesised by precipitation method in EG-H{sub 2}O. • BiOCl{sub x}I{sub y} catalyst possessed high surface area and small particle size. • BiOCl{sub 0.75}I{sub 0.25} showed the best photocatalytic ability of p-HPA and ACTP. • Degradation of p-HPA and ACTP primarily proceeded by O{sub 2}·{sup −}. - Abstract: BiOCl{sub x}I{sub y} nanospheres have been synthesised via precipitation method in ethylene glycol (EG)-water (H{sub 2}O) mixed solvent at 80 °C and ambient pressure. Results of BiOCl{sub x}I{sub y} characterisation showed that these composite materials well combined BiOCl with BiOI crystals, which displayed flower-like hierarchical nanospheres consisted of numerous nanosheets and possessed smaller particle size, higher surface area than those in previous papers. The great surface area resulted in its high adsorption abilities of hydroxyphenylacetic acid (p-HPA) in the dark, the adsorption process could be suitably described by a pseudo-second-order kinetics model and the adsorption isotherms could be well fitted with Freundlich and Langmuir equations. The photocatalytic degradation of p-HPA and acetaminophen (ACTP) were investigated under simulated solar and visible irradiation using BiOCl{sub x}I{sub y} catalyst for the first time. The combination of BiOCl and BiOI to a certain extent has largely improved the remove efficiency, and BiOCl{sub 0.75}I{sub 0.25} was the optimal catalyst with almost 100% removal of p-HPA and 80% removal of ACTP under solar light for 3 h. Experimental results demonstrated that the photocatalytic degradation of p-HPA and ACTP followed pseudo-first-order kinetics and O{sub 2}·{sup −} and dissolved oxygen play predominant roles in photocatalytic process efficiency. This research will supply an environment-friendly photocatalyst for pharmaceutical wastewater treatment under sunlight.

  4. Efficient photocatalytic degradation of perfluorooctanoic acid by a wide band gap p-block metal oxyhydroxide InOOH

    Xu, Jingjing; Wu, Miaomiao; Yang, Jingwen; Wang, Zhengmei; Chen, Mindong; Teng, Fei

    2017-09-01

    In this work, we prepared a new wide band gap semiconductor, p-block metal oxyhydroxide InOOH, which exhibits efficient activity for perfluorooctanoic acid (PFOA) degradation under mild conditions and UV light irradiation. The apparent rate constant for PFOA degradation by InOOH is 27.6 times higher than that for P25 titania. Results show that ionized PFOA (C7F15COO-) can be adsorbed much more efficiently on the surface of InOOH than P25. Then, the adsorbed C7F15COO- can be decomposed directly by photo-generated holes to form C7F15COOrad radicals. This process is the key step for the photocalytic degradation of PFOA. Major degradation intermediates, fluoride ions and perfluorinated carboxylic acids (PFCAs) with shorter chain lengths were detected during PFOA degradation. A possible pathway for photocatalytic degradation of PFOA is proposed based on the experimental results. Therefore, this studies indicates a potential new material and method for the efficient treatment of PFCA pollutants under mild conditions.

  5. Utilization of visible to NIR light energy by Yb"+"3, Er"+"3 and Tm"+"3 doped BiVO_4 for the photocatalytic degradation of methylene blue

    Regmi, Chhabilal; Kshetri, Yuwaraj K.; Ray, Schindra Kumar; Pandey, Ramesh Prasad; Lee, Soo Wohn

    2017-01-01

    Highlights: • Lanthanide doped BiVO_4 as highly efficient upconversion and photocatalytic material. • Well defined beads like morphology for better photocatalytic activity. • Effective utilization of NIR and visible light for efficient photocatalytic degradation of methylene blue. • Nontoxic to human cells, potential for application in biological fields. - Abstract: Lanthanide-doped BiVO_4 semiconductors with efficient photocatalytic activities over a broad range of the solar light spectrum have been synthesized by the microwave hydrothermal method using ethylenediaminetetraacetic acid (EDTA). The structural, morphological, and optical properties of the as-synthesized samples were evaluated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS). The toxicity of the samples was measured using Mus musculus skin melanoma cells (B16-F10 (ATCC"® CRL-6475™)) and were found to be nontoxic for human cells. The photocatalytic efficiency of the prepared samples was evaluated by methylene blue (MB) degradation. The best photocatalytic activity was shown by BiVO_4 with 6:3:3 mol percentage of Yb"+"3:Er"+"3:Tm"+"3 in all solar light spectrum. The synthesized samples possess low band gap energy and a hollow structure suitable for the better photocatalytic activity. The observed NIR photoactivity supports that the upconversion mechanism is involved in the overall photocatalytic process. Therefore, this approach provides a better alternative upconversion material for integral solar light absorption.

  6. Photocatalytic degradation of aqueous ammonia by using TiO{sub 2}−ZnO/LECA hybrid photocatalyst

    Mohammadi, Zahra; Sharifnia, Shahram, E-mail: sharif@razi.ac.ir; Shavisi, Yaser

    2016-12-01

    A novel hybrid structure of TiO{sub 2}−ZnO photocatalyst which immobilized on light expanded clay aggregate (LECA) support was applied for efficient removal of ammonia from synthetic wastewater. This photocatalyst was successfully prepared by a simple method and characterized by FESEM, FTIR, UV–vis, and PL techniques. LECA granules were used as support due to their low weight and high porosity surface. Compared with the pure TiO{sub 2} and ZnO, the hybrid photocatalyst had a significant effect on its properties such as photoluminescence and UV visible absorption. The coupled Ti:Zn photocatalyst with molar ratio of 1:2 exhibited the lowest photoluminescence emission intensity and maximum photocatalytic degradation of ammonia in aqueous solution. For evaluating performance of the hybrid photocatalyst, the effect of various parameters such as initial feed concentration, pH of solution, and photocatalyst dosage on the ammonia photodegradation rate were systematically investigated. The optimal pH, catalyst loading, and initial concentration of ammonia were obtained to be ≈ 11, 25 g/L, and 400 mg/L, respectively. Also, in the optimal conditions, 95.2% ammonia removal was achieved during 3 h of UV irradiation. The discussions were based on the mobility and lifetime of the charge carriers generated in the TiO{sub 2}−ZnO composite. - Highlights: • A hybrid structure of TiO{sub 2}−ZnO/LECA was applied for photocatalytic removal of ammonia. • Hybrid photocatalyst had a significant effect on photoluminescence and UV–vis absorption. • Coupled Ti:Zn photocatalyst (molar ratio = 1:2) exhibited max. photocatalytic degradation. • Optimal conditions: pH ≈ 11, catalyst loading = 25 g/L, and initial concentration = 400 mg/L. • In optimal conditions 95.2% ammonia removal was achieved during 3 h of UV irradiation.

  7. Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

    Silva, M. [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal, F-63177 Aubiere cedex (France); Calvete, M.J.F.; Goncalves, N.P.F.; Burrows, H.D. [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Sarakha, M. [Laboratoire de Photochimie Moleculaire et Macromoleculaire, UMR CNRS 6505, Universite Blaise Pascal, F-63177 Aubiere cedex (France); Fernandes, A.; Ribeiro, M.F. [Instituto para a Biotecnologia e Bioengenharia, Centro para a Engenharia Biologica e Quimica, Instituto Superior Tecnico - Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Azenha, M.E., E-mail: meazenha@ci.uc.pt [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal); Pereira, M.M., E-mail: mmpereira@qui.uc.pt [Departamento de Quimica, Universidade de Coimbra, Rua Larga, 3004-535 Coimbra (Portugal)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Complete immobilization of zinc(II) phthalocyanines accomplished in Al-MCM-41. Black-Right-Pointing-Pointer Efficient photodegradation of model pesticides achieved using 365 nm irradiation. Black-Right-Pointing-Pointer Sodium azide experiments showed the involvement of singlet oxygen ({sup 1}O{sub 2}). - Abstract: In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV-vis spectroscopy (DRS-UV-vis), luminescence, thermogravimetric analysis (TG/DSC), N{sub 2} adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320-460 nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc-Al-MCM-41 and ZnTTMAEOPcI-Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI-Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC-MS product characterization and mechanistic studies indicate that singlet oxygen ({sup 1}O{sub 2}), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

  8. Facile synthesis of ZnO/CuInS{sub 2} nanorod arrays for photocatalytic pollutants degradation

    Yang, Yawei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Zhang, Xinyu [Frontier Institute of Science and Technology Jointly with College of Science, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Xing, Yonglei; Yin, Xingtian [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Du, Yaping, E-mail: ypdu2013@mail.xjtu.edu.cn [Frontier Institute of Science and Technology Jointly with College of Science, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China)

    2016-11-05

    Highlights: • Vertically-aligned ZnO nanorod arrays were synthesized by the hydrothermal process. • Monodisperse CuInS{sub 2} QDs were synthesized by the one-pot colloidal chemistry method. • ZnO/CuInS{sub 2} nanorod arrays films were fabricated by the EPD process. • The homogeneous CuInS{sub 2} loading was optimized by EPD duration. • The photoelectrochemical and photocatalytic activities of the ZnO/CuInS{sub 2} nanorod arrays films were discussed. - Abstract: Vertically-aligned ZnO nanorod arrays on a fluorine-doped tin oxide glass substrate were homogeneously coated with visible light active CuInS{sub 2} quantum dots by using a controllable electrophoretic deposition strategy. Compared with the pure ZnO nanorod arrays, the formation of high-quality ZnO/CuInS{sub 2} heterojunction with well-matched band energy alignment expanded the light absorption from ultraviolet to visible region and facilitated efficient charge separation and transportation, thus yielding remarkable enhanced photoelectrochemical performance and photocatalytic activities for methyl orange and 4-chlorophenol degradation. The ZnO/CuInS{sub 2} film with the deposition duration of 80 min showed the highest degradation rate and photocurrent density (0.95 mA/cm{sup 2}), which was almost 6.33 times higher than that of the pure ZnO nanorod arrays film. The CuInS{sub 2} QDs sensitized ZnO nanorod arrays film was proved to be a superior structure for photoelectrochemical and photocatalytic applications due to the optimized CuInS{sub 2} loading and well-maintained one-dimensional nanostructure.

  9. Design of binary SnO_2-CuO nanocomposite for efficient photocatalytic degradation of malachite green dye

    Kumar, Aniket; Rout, Lipeeka; Achary, L. Satish Kumar; Mohanty, Anurag; Marpally, Jyoshna; Chand, Pradyumna Kumar; Dash, Priyabrat

    2016-01-01

    Semiconductor mediated photocatalysis has got enormous consideration as it has shown immense potential in addressing the overall energy and environmental issues. To overcome the earlier drawbacks concerning quick charge recombination and limited visible-light absorption of semiconductor photocatalysts, numerous methods have been produced in the past couple of decades and the most broadly utilized one is to develop the photocatalytic heterojunctions. In our work, a series of SnO_2-CuO nanocomposites of different compositions were synthesized by a combustion method and have been investigated in detail by various characterization techniques, such as wide angle X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanocomposites were almost same for all the compositions. FE-SEM images showed that the shape of SnO_2-CuO was spherical in nature and the 1: 1 Sn/Cu sample had a well-proportioned morphology. The malachite green dye was used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer for different composition ratio of metal (Sn: Cu) such as 1:1, 1:2, 2:1, 1:0.5 and 0.5:1. The 1:1 ratio nanocomposite showed excellent photocatalytic degradation of 96 % compared to pure SnO_2 and CuO. The mechanism of degradation and charge separation ability of the nanocomposite are also explored using photocurrent measurement study.

  10. Enhanced Photocatalytic Degradation of Methyl Orange Dye under the Daylight Irradiation over CN-TiO₂ Modified with OMS-2.

    Hassan, Mohamed Elfatih; Chen, Jing; Liu, Guanglong; Zhu, Duanwei; Cai, Jianbo

    2014-12-12

    In this study, CN-TiO₂ was modified with cryptomelane octahedral molecular sieves (OMS-2) by the sol-gel method based on the self-assembly technique to enhance its photocatalytic activity under the daylight irradiation. The synthesized samples were characterized by X-ray diffraction (XRD), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and porosimeter analysis. The results showed that the addition of OMS-2 in the sol lead to higher Brunauer-Emmett-Teller (BET) surface area, pore volume, porosity of particle after heat treatment and the specific surface area, porosity, crystallite size and pore size distribution could be controlled by adjusting the calcination temperature. Compared to the CN-TiO₂-400 sample, CN-TiO₂/OMS-2-400 exhibited greater red shift in absorption edge of samples in visible region due to the OMS-2 coated. The enhancement of photocatalytic activity of CN-TiO₂/OMS-2 composite photocatalyst was subsequently evaluated for the degradation of the methyl orange dye under the daylight irradiation in water. The results showed that the methyl orange dye degradation rate reach to 37.8% for the CN-TiO₂/OMS-2-400 sample under the daylight irradiation for 5 h, which was higher than that of reference sample. The enhancement in daylight photocatalytic activities of the CN-TiO₂/OMS samples could be attributed to the synergistic effects of OMS-2 coated, larger surface area and red shift in adsorption edge of the prepared sample.

  11. AgBr/diatomite for the efficient visible-light-driven photocatalytic degradation of Rhodamine B

    Fang, Jing; Zhao, Huamei; Liu, Qinglei; Zhang, Wang; Gu, Jiajun; Su, Yishi; Abbas, Waseem; Su, Huilan; You, Zhengwei; Zhang, Di

    2018-03-01

    The treatment of organic pollution via photocatalysis has been investigated for a few decades. However, earth-abundant, cheap, stable, and efficient substrates are still to be developed. Here, we prepare an efficient visible-light-driven photocatalyst via the deposition of Ag nanoparticles (light intensity. For comparison, AgBr/SiO2 ( κ = 0.04 min-1) and commercial AgBr nanoparticles ( κ = 0.05 min-1) were measured as well. The experimental results reveal that diatomite acted more than a substrate benefiting the dispersion of AgBr nanoparticles, as well as a cooperator to help harvest visible light and adsorb dye molecules, leading to the efficient visible-light-driven photocatalytic performance of AgBr/diatomite. Considering the low cost (10 per ton) and large-scale availability of diatomite, our study provides the possibility to prepare other types of diatomite-based efficient photocatalytic composites with low-cost but excellent photocatalytic performance.

  12. Microwave-assisted synthesis of triple-helical, collagen-mimetic lipopeptides

    Banerjee, Jayati; Hanson, Andrea J; Muhonen, Wallace W; Shabb, John B; Mallik, Sanku

    2018-01-01

    Collagen-mimetic peptides and lipopeptides are widely used as substrates for matrix degrading enzymes, as new biomaterials for tissue engineering, as drug delivery systems and so on. However, the preparation and subsequent purification of these peptides and their fatty-acid conjugates are really challenging. Herein, we report a rapid microwave-assisted, solid-phase synthetic protocol to prepare the fatty-acid conjugated, triple-helical peptides containing the cleavage site for the enzyme matrix metalloproteinase-9 (MMP-9). We employed a PEG-based resin as the solid support and the amino acids were protected with Fmoc- and tert-butyl groups. The amino acids were coupled at 50 °C (25 W of microwave power) for 5 min. The deprotection reactions were carried out at 75 °C (35 W of microwave power) for 3 min. Using this protocol, a peptide containing 23 amino acids was synthesized and then conjugated to stearic acid in 14 h. PMID:20057380

  13. Optimisation of microwave-assisted processing in production of pineapple jam

    Ismail, Nur Aisyah Mohd; Abdullah, Norazlin; Muhammad, Norhayati

    2017-10-01

    Pineapples are available all year round since they are unseasonal fruits. Due to the continuous harvesting of the fruit, the retailers and farmers had to find a solution such as the processing of pineapple into jam, to treat the unsuccessfully sold pineapples. The direct heating of pineapple puree during the production of pineapple jam can cause over degradation of quality of the fresh pineapple. Thus, this study aims to optimise the microwave-assisted processing conditions for producing pineapple jam which could reduce water activity and meets minimum requirement for pH and total soluble solids contents of fruit jam. The power and time of the microwave processing were chosen as the factors, while the water activity, pH and total soluble solids (TSS) content of the pineapple jam were determined as responses to be optimised. The microwave treatment on the pineapple jam was able to give significant effect on the water activity and TSS content of the pineapple jam. The optimum power and time for the microwave processing of pineapple jam is 800 Watt and 8 minutes, respectively. The use of domestic microwave oven for the pineapple jam production results in acceptable pineapple jam same as conventional fruit jam sold in the marketplace.

  14. Efficient photocatalytic degradation of ibuprofen in aqueous solution using novel visible-light responsive graphene quantum dot/AgVO{sub 3} nanoribbons

    Lei, Zhen-dong [Department of Physics, Tsinghua University, Beijing 100084 (China); Wang, Jia-jun [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China); Wang, Liang, E-mail: wangl@shu.edu.cn [Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444 (China); Yang, Xiong-yu; Xu, Gang [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China); Tang, Liang, E-mail: tang1liang@shu.edu.cn [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China)

    2016-07-15

    Highlights: • A novel heterojunction photocatalyst, GQD/AgVO{sub 3} was prepared. • The morphology of GQD/AgVO{sub 3} was well characterized. • Ibuprofen was easily decomposed using GQD/AgVO{sub 3} under visible-light irradiation. • The degradation pathway of ibuprofen was also suggested. - Abstract: Single crystalline, non-toxicity, and long-term stability graphene quantum dots (GQDs) were modified onto the AgVO{sub 3} nanoribbons by a facile hydrothermal and sintering technique which constructs a unique heterojunction photocatalyst. Characterization results indicate that GQDs are well dispersed on the surface of AgVO{sub 3} nanoribbons and GQD/AgVO{sub 3} heterojunctions are formed, which can greatly promote the separation efficiency of photogenerated electron-hole pairs under visible light irradiation. By taking advantage of this feature, the GQD/AgVO{sub 3} heterojunctions exhibit considerable improvement on the photocatalytic activities for the degradation of ibuprofen (IBP) under visible light irradiation as compared to pure AgVO{sub 3}. The photocatalytic activity of GQD/AgVO{sub 3} heterojunctions is relevant with GQD ratio and the optimal activity is obtained at 3 wt% with the highest separation efficiency of photogenerated electron-hole pairs. Integrating the physicochemical and photocatalytic properties, the factors controlling the photocatalytic activity of GQD/AgVO{sub 3} heterojunctions are discussed in detail. Moreover, potential photocatalytic degradation mechanisms of IBP via GQD/AgVO{sub 3} heterojunctions under visible light are proposed.

  15. Activity of nanosized titania synthesized from thermal decomposition of titanium (IV n-butoxide for the photocatalytic degradation of diuron

    Jitlada Klongdee, Wansiri Petchkroh, Kosin Phuempoonsathaporn, Piyasan Praserthdam, Alisa S. Vangnai and Varong Pavarajarn

    2005-01-01

    Full Text Available Nanoparticles of anatase titania were synthesized by the thermal decomposition of titanium (IV n-butoxide in 1,4-butanediol. The powder obtained was characterized by various characterization techniques, such as XRD, BET, SEM and TEM, to confirm that it was a collection of single crystal anatase with particle size smaller than 15 nm. The synthesized titania was employed as catalyst for the photodegradation of diuron, a herbicide belonging to the phenylurea family, which has been considered as a biologically active pollutant in soil and water. Although diuron is chemically stable, degradation of diuron by photocatalyzed oxidation was found possible. The conversions achieved by titania prepared were in the range of 70–80% within 6 h of reaction, using standard UV lamps, while over 99% conversion was achieved under solar irradiation. The photocatalytic activity was compared with that of the Japanese Reference Catalyst (JRC-TIO-1 titania from the Catalysis Society of Japan. The synthesized titania exhibited higher rate and efficiency in diuron degradation than reference catalyst. The results from the investigations by controlling various reaction parameters, such as oxygen dissolved in the solution, diuron concentration, as well as light source, suggested that the enhanced photocatalytic activity was the result from higher crystallinity of the synthesized titania.

  16. Sulfur-Doped Carbon Nitride Polymers for Photocatalytic Degradation of Organic Pollutant and Reduction of Cr(VI).

    Zheng, Yun; Yu, Zihao; Lin, Feng; Guo, Fangsong; Alamry, Khalid A; Taib, Layla A; Asiri, Abdullah M; Wang, Xinchen

    2017-04-01

    As a promising conjugated polymer, binary carbon nitride has attracted extensive attention as a metal-free and visible-light-responsive photocatalyst in the area of photon-involving purification of water and air. Herein, we report sulfur-doped polymeric carbon nitride microrods that are synthesized through thermal polymerization based on trithiocyanuric acid and melamine (TM) supramolecular aggregates. By tuning the polymerization temperature, a series of sulfur-doped carbon nitride microrods are prepared. The degradation of Rhodamine B (RhB) and the reduction of hexavalent chromium Cr(VI) are selected as probe reactions to evaluate the photocatalytic activities. Results show that increasing pyrolysis temperature leads to a large specific surface area, strong visible-light absorption, and accelerated electron-hole separation. Compared to bulk carbon nitride, the highly porous sulfur-doped carbon nitride microrods fabricated at 650 °C exhibit remarkably higher photocatalytic activity for degradation of RhB and reduction of Cr(VI). This work highlights the importance of self-assembly approach and temperature-control strategy in the synthesis of photoactive materials for environmental remediation.

  17. Enhanced Photocatalytic Degradation and Mineralization of Furfural Using UVC/TiO2/GAC Composite in Aqueous Solution

    Bahram Ghasemi

    2016-01-01

    Full Text Available Titanium dioxide nanoparticles were immobilized on granular activated carbon (GAC as a porous and low-density support for photocatalytic degradation of furfural. The TiO2/GAC composite was synthetized using the simple sol-gel method and fully characterized. The effects of the operational parameters of furfural concentration (200–700 mg/L, initial pH (2–12, TiO2/GAC composite dosage (1–3.5 g/L, and irradiation time (20–120 min were studied. The synthetized TiO2/GAC composite exhibited a total pore volume of 0.13 cm3/g and specific surface area of 35.91 m2/g. Removal efficiency of up to 95% was observed at initial pH of 10, TiO2/GAC dosage of 2.5 g/L, irradiation time of 80 min, and initial furfural concentration of 500 mg/L. The photocatalyst could be reused at least four consecutive times with a mere 2% decrease in furfural removal efficiency. Mineralization efficiency of 94% was obtained within 80 min. Pseudo-first-order kinetics best fit the photocatalytic degradation of furfural under experimental conditions.

  18. Synthesis of nano-TiO{sub 2}/diatomite composite and its photocatalytic degradation of gaseous formaldehyde

    Zhang, Guangxin; Sun, Zhiming, E-mail: zhimingsun@cumtb.edu.cn; Duan, Yongwei; Ma, Ruixin; Zheng, Shuilin, E-mail: shuilinzheng8@gmail.com

    2017-08-01

    Highlights: • TiO{sub 2}/diatomite composite was synthesized by hydrolysis deposition method. • The composite displayed higher photocatalytic performance for formaldehyde. • The dispersion effect of diatomite was a key factor for high photoactivity. • The composite is a promising photocatalyst for the indoor air purification. - Abstract: The TiO{sub 2}/diatomite composite was synthesized through a mild hydrolysis of titanyl sulfate. The prepared composite was characterized by X-ray diffraction, N{sub 2} adsorption–desorption, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffused reflectance spectroscopy. The results demonstrate that the anatase TiO{sub 2} nanopartilces anchored on the surface of diatomite with Ti–O–Si bonds between diatomite and TiO{sub 2}. The photodegradation of gaseous formaldehyde under UV irradiation by the TiO{sub 2}/diatomite composite was studied under various operating conditions, including relative humidity, illumination intensity and catalyst amount, which have significant influence on the degradation process. The TiO{sub 2}/diatomite composite exhibited better photocatalytic activity than pure TiO{sub 2}, which could be attributed to the favorable nanoparticles dispersibility and strong formaldehyde adsorption capacity. In addition, the composite exhibited outstanding reusability over five cycles. The TiO{sub 2}/diatomite composite shows great promising application foreground in formaldehyde degradation.

  19. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    Li Jinhuan; Yang Xia; Yu Xiaodan; Xu, Leilei; Kang Wanli; Yan Wenhua; Gao Hongfeng; Liu Zhonghe; Guo Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+ /TiO 2 , where RE = Eu 3+ , Pr 3+ , Gd 3+ , Nd 3+ , and Y 3+ ) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+ , Pr 3+ )/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+ /TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  20. Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles

    Whang, Thou-Jen; Hsieh, Mu-Tao; Chen, Huang-Han

    2012-01-01

    The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO 3 relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).

  1. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye pollutants in water using natural chromite—response surface optimization

    Shaban, Mohamed; Abukhadra, Mostafa R.; Ibrahim, Suzan S.; Shahien, Mohamed. G.

    2017-12-01

    Refined natural Fe-chromite was characterized by XRD, FT-IR, reflected polarized microscope, XRF and UV spectrophotometer. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye by Fe-chromite was investigated using 1 mL H2O2. The degradation of dye was studied as a function of illumination time, chromite mass, initial dye concentration, and pH. Fe-chromite acts as binary oxide system from chromium oxide and ferrous oxide. Thus, it exhibits photocatalytic properties under UV illumination and photo-Fenton oxidation after addition of H2O2. The degradation in the presence of H2O2 reached the equilibrium stage after 8 h (59.4%) but in the absence of H2O2 continued to 12 h (54.6%). Photocatalytic degradation results fitted well with zero, first order and second order kinetic model but it represented by second order rather than by the other models. While the photo-Fenton oxidation show medium fitting with the second order kinetic model only. The values of kinetic rate constants for the photo-Fenton oxidation were greater than those for the photocatalytic degradation. Thus, degradation of Congo red dye using chromite as catalyst is more efficient by photo-Fenton oxidation. Based on the response surface analysis, the predicted optimal conditions for maximum removal of Congo red dye by photocatalytic degradation (100%) were 12 mg/l, 0.14 g, 3, and 11 h for dye concentration, chromite mass, pH, and illumination time, respectively. Moreover, the optimum condition for photo-Fenton oxidation of dye (100%) is 13.5 mg/l, 0.10 g, 4, and 10 h, respectively.

  2. Photocatalytic degradation of p,p'-DDT under UV and visible light using interstitial N-doped TiO₂.

    Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat

    2015-01-01

    1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p'-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p'-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol-gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p'-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p'-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p'-DDT effectively under both UV and visible lights. The rate constant of the p,p'-DDT degradation under UV light was only 0.0121 min(-1), whereas the rate constant of the p,p'-DDT degradation under visible light was 0.1282 min(-1). Under visible light, the 100% degradation of p,p'-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p'-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg(-1), and the apparent reaction rate constant (k) was 1.3941 mg L(-1)-min. Major intermediates detected during the p,p'-DDT degradation were p,p'-DDE, o,p'-DDE, p,p'-DDD and p,p'-DDD. Results from this work can be applied further for the breakdown of p,p'-DDT molecule in the real contaminated water using this technology.

  3. HETEROGENEOUS PHOTOCATALYTIC DEGRADATION OF PHENOL IN AQUEOUS SUSPENSION OF PERIWINKLE SHELL ASH CATALYST IN THE PRESENCE OF UV FROM SUNLIGHT

    OSARUMWENSE, J. O.

    2015-12-01

    Full Text Available The batch photocatalytic degradation of phenol in aqueous solution wasinvestigated using periwinkle shell ash (PSA as photocatalyst. Chemical characterisation of the PSA revealed that the major oxides present were calcium oxide (CaO, silica (SiO2 and aluminium oxide (Al2O3 which accounted for 41.3, 33.2 and 9.2% of the weight of PSA characterised. The major elements in PSA were iron (19.2% and zinc (16.5%. FTIR results revealed absorption peaks of 3626.59 cm−1, 1797.58 cm−1, 1561.43 cm−1 and 1374.34 cm−1 in the infrared spectrum of PSA corresponding to O–H, C= O, C= C and C–H bonds respectively. Increasing the initial phenol concentration resulted in a decrease in the degradation efficiency of PSA. Lower catalyst loadings favoured the degradation process. Maximum degradation efficiency was obtained when the initial phenol concentration and catalyst loading were set as 50 g/L and 5 g/L respectively. The kinetics of the degradation process was well described by the pseudo first order equation while the diffusion mechanism was well represented by the intra particle diffusion model (R2>0.90. The adsorption equilibrium data fitted well to the Langmuir isotherm equation with an R2 value of 0.997.

  4. Photocatalytic degradation of crystal violet by thiourea-doped TiO2 ...

    In this study, optimisation of the photocatalytic behaviour of crystal violet (CV) by thiourea (Tu)-codoped TiO2 thin film in fixed bed photoreactor was investigated by central composite designs (CCDs). The effective variables were pH, the concentration of CV dye, flow rate and reaction time. The results of the CCD model ...

  5. Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

    Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

    2018-04-01

    Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.

  6. Enhanced photocatalytic degradation and adsorption of methylene blue via TiO{sub 2} nanocrystals supported on graphene-like bamboo charcoal

    Wu, Fangjun; Liu, Wei, E-mail: wlscau@163.com; Qiu, Jielong; Li, Jinzhen; Zhou, Wuyi; Fang, Yueping; Zhang, Shuting, E-mail: zhangshuting@gmail.com; Li, Xin, E-mail: Xinliscau@yahoo.com

    2015-12-15

    Graphical abstract: - Abstract: In this study, a novel efficient photocatalytic nanomaterial, TiO{sub 2} nanocrystals supported on graphene-like bamboo charcoal, has been successfully synthesized via a facile multi-step process. The structural and optical properties of the as-prepared samples were characterized by different techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis absorption spectroscopy, photoluminescence spectra (PL), Raman spectra and nitrogen adsorption–desorption isotherms. The photocatalytic activities under sunlight were evaluated by the degradation of methylene blue (MB). The results indicated that the ternary hybrid photocatalysts exhibited much higher photocatalytic activities toward the degradation of MB than the pure TiO{sub 2} under UV light irradiation. Moreover, the optimum weight content of graphene-like bamboo charcoal in composite photocatalysts was 6 wt% for achieving the maximum photocatalytic degradation rate. The apparent rate constant of the best sample (0.0509 min{sup −1}) was about 3 times greater than that of the commercial P25 (0.0170 min{sup −1}). The adsorption and degradation kinetics of MB can be described by the pseudo-first-order model and apparent first-order kinetics model, respectively. The highly enhanced photocatalytic performance was attributed to the synergetic effect of graphene-like carbon and bamboo charcoal, which lead to the promoted charge separation and reduction reaction of oxygen, and enhanced adsorption capacities of MB, respectively. The composite photocatalysts displayed a high photochemical stability under repeated irradiation. This work may provide new insights and understanding on the graphene-like bamboo charcoal as an excellent support for photocatalyst nanoparticles to enhance their visible-light photocatalytic activity.

  7. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-07-01

    A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV-vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhBaq-visible light system was O2-rad ; nevertheless, h+ and rad OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the reusability of 1.5-CdS/MIL composite was also studied.

  8. TiO2 structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

    Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

    2017-05-01

    Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

  9. Preparation of flower-like TiO{sub 2} sphere/reduced graphene oxide composites for photocatalytic degradation of organic pollutants

    Kim, Tae-Woong [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Mira [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Hak Yong [Department of BIN Convergence technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of)

    2016-07-15

    In this study, novel flower-like TiO{sub 2} sphere (FTS)/reduced graphene oxide (rGO) composites (FTS-G) were synthesized via a hydrothermal method. The photocatalytic performance of the FTS-G composites was evaluated through the photodegradation of rhodamine B (Rh B) and trichloroethylene (TCE) under simulated solar light irradiation. The rGO to FTS ratio in the composites significantly affected photocatalytic activity. The photocatalytic activities of FTS-Gs in the degradation of Rh B and TCE were superior to that of pure FTS. Of all the FTS-G composites tested, FTS-G with 1 wt% rGO (FTS-G-1) had the greatest photocatalytic activity, while FTS-G composites with rGO contents over 1 wt% had lower photocatalytic activities. Additionally, it is expected that the synthesis of FTS with a high specific surface area and well-developed pore structure and simultaneous conversion of GO to graphene-like rGO without the use of strong reducing agents could be a promising strategy to prepare other carbon-based flower-like TiO{sub 2} sphere composite photocatalysts. - Graphical abstract: Schematic illustration of high photocatalytic activity for FTS-G composites. Display Omitted.

  10. Rapid and efficient visible light photocatalytic dye degradation using AFe2O4 (A = Ba, Ca and Sr) complex oxides

    Vijayaraghavan, T.; Suriyaraj, S.P.; Selvakumar, R.; Venkateswaran, R.; Ashok, Anuradha

    2016-01-01

    Highlights: • Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca and Sr) were synthesized by sol–gel method. • Visible light photocatalytic activity of these ferrites were studied using congo red dye degradation. • BaFe 2 O 4 exhibited the best photocatalytic activity under visible light (xenon lamp) irradiation; CaFe 2 O 4 was the best photocatalyst under natural sun light irradiation. - Abstract: Photocatalytic activity of spinel type complex oxides has been investigated in this study. Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca, Sr) were synthesized by sol–gel method. Structural characterizations reveal that the synthesized ferrites have orthorhombic crystal structures with different space groups and cell dimensions when they have different alkaline earth metals in their A site. All the synthesized ferrites exhibited their bandgap in the range 2.14–2.19 eV. Their photocatalytic activities were studied using congo red dye under sunlight and xenon lamp radiation. The substitution of Ba, Ca and Sr at A site of these ferrites had varying impact on dye degradation process. Under xenon lamp irradiation, BaFe 2 O 4 exhibited the highest percentage of dye degradation (92% after 75 min). However, CaFe 2 O 4 showed the fastest degradation of the dye (70% within 15 min). In the absence of irradiation, SrFe 2 O 4 showed the highest dye adsorption (44% after 75 min).

  11. Electrophoretic deposition of CdS coatings and their photocatalytic activities in the degradation of tetracycline antibiotic

    Vázquez, A., E-mail: alejandro.lqi@gmail.com [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico); Hernández-Uresti, D.B., E-mail: ing.dianahdz@gmail.com [Universidad Autónoma de Nuevo León, CICFIM–Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico); Obregón, S. [Universidad Autónoma de Nuevo León, CICFIM–Facultad de Ciencias Físico Matemáticas, Av. Universidad S/N, San Nicolás de los Garza, 66455 Nuevo León (Mexico)

    2016-11-15

    Highlights: • CdS photocatalyst was prepared by electrophoretic deposition. • The CdS coating was used in the photodegradation of antibiotics. • O{sub 2}{sup −} and ·OH radicals were responsible for the degradation of tetracycline. - Abstract: The photocatalytic activities of CdS coatings formed by electrophoretic deposition (EPD) were evaluated through the photodegradation of an antibiotic, tetracycline. First, CdS nanoparticles were synthesized under microwave irradiation of aqueous solutions containing the cadmium and sulfur precursors at stoichiometric amounts and by using trisodium citrate as stabilizer. Microwave irradiation was carried out in a conventional microwave oven at 2.45 GHz and 1650 W of nominal power, for 60 s. The CdS nanoparticles were characterized by UV–vis spectrophotometry, photoluminescence and X-ray diffraction. Electrophoretic deposition parameters were 300 mV, 600 mV and 900 mV of applied voltage between aluminum plates separated by 1 cm. The fractal dimensions of the surfaces were evaluated by atomic force microscopy and correlated to the morphological and topographic characteristics of the coatings. The photocatalytic activity of the CdS coatings was investigated by means the photodegradation of the tetracycline antibiotic under simulated sunlight irradiation. According to the results, the photoactivity of the coatings directly depends on the concentration of the precursors and the applied voltage during the deposition. The material obtained at 600 mV showed the best photocatalytic behavior, probably due to its physical properties, such as optimum load and suitable aggregate size.

  12. Photocatalytic Degradation of Bisphenol A from Aqueous Solutions using TiO2 Nanoparticles and UV Illumination

    Ramzan ali Dianati

    2014-12-01

    Full Text Available Background and Purpose: Bisphenol A (BPA is used to make certain plastics and epoxy resins. It is a non-biodegradable compound, and poses health risks to both humans and animals. The purpose of this study was to evaluate decomposition efficiency of BPA from aqueous solutions using UV irradiation. Materials and Methods: In this study, the photodegradation of BPA in water were carried out in a reactor equipped 6 W UV lamp. In order to obtain the optimum operational conditions, parameters such as BPA concentration (1-50 mg/l, TiO2 dosage (0.025-2 g/l, and pH (3-11 were evaluated. BPA concentration was measured by high-performance liquid chromatography. Results: The highest degradation was 90% and achieved in 60 min. BPA degradation efficiency can be effectively improved by increasing pH, decreasing the initial concentration and increasing TiO2 dosage. The optimal dose of TiO2 was measured at 0.5 g/l. The degradation decreases with increasing TiO2 dosage. Conclusion: Photocatalytic degradation by using TiO2 and low power UV lamp is applicable.

  13. Photolytic and photocatalytic degradation of quinclorac in ultrapure and paddy field water: identification of transformation products and pathways.

    Pareja, Lucía; Pérez-Parada, Andrés; Agüera, Ana; Cesio, Verónica; Heinzen, Horacio; Fernández-Alba, Amadeo R

    2012-05-01

    Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO(2) photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700 W m(-2), respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40 min of TiO(2) photocatalysis in ultrapure water, whereas 130 min were necessary to degrade 98% of the initial concentration in paddy field water. Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Surface modification of titanium hydride with epoxy resin via microwave-assisted ball milling

    Ning, Rong; Chen, Ding; Zhang, Qianxia; Bian, Zhibing; Dai, Haixiong; Zhang, Chi

    2014-01-01

    Highlights: • TiH 2 was modified with epoxy resin by microwave-assisted ball milling. • The epoxy ring was opened under the coupling effect of microwave and ball milling. • Microwave-assisted ball milling improved the compatibility of TiH 2 with epoxy. - Abstract: Surface modification of titanium hydride with epoxy resin was carried out via microwave-assisted ball milling and the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermo-gravimetry (TG) and Fourier transform infrared spectroscopy (FT-IR). A sedimentation test was performed to investigate the compatibility of the modified nano titanium hydride with the epoxy resin. The results show that the epoxy resin molecules were grafted on the surface of nano titanium hydride particles during the microwave-assisted ball milling process, which led to the improvement of compatibility between the nanoparticles and epoxy resin. According to the FT-IR, the grafting site was likely to be located around the epoxy group due to the fact that the epoxy ring was opened. However, compared with microwave-assisted ball milling, the conventional ball milling could not realize the surface modification, indicating that the coupling effect of mechanical force and microwave played a key role during the process

  15. TiO₂ (rutile) embedded inulin--A versatile bio-nanocomposite for photocatalytic degradation of methylene blue.

    Jayanthi Kalaivani, G; Suja, S K

    2016-06-05

    Inulin, a water soluble carbohydrate polymer, was extracted from Allium sativum L. by hot water diffusion method. A novel bio-nanocomposite was prepared by embedding TiO2 (rutile) onto the inulin matrix. The extracted inulin and the prepared bio-nanocomposite were characterized using UV-vis, FT-IR, XRD, SEM, TEM and TGA techniques. The photocatalytic activity of the bio-nanocomposite for the degradation of methylene blue was studied under UV illumination in batch mode experiment and was found to be twice as high as that of pristine TiO2. The kapp for inulin-TiO2 (0.0449 min(-1)) was higher than that for TiO2 (0.0325 min(-1)) which may be due to the synergistic action of inulin and TiO2. The stabilization of photo excited electron suppressed the electron-hole pair recombination thereby inducing the electrons and the holes to participate in the photo reduction and oxidation processes, respectively and enhancing the photocatalytic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Anatase vs. rutile efficiency on the photocatalytic degradation of clofibric acid under near UV to visible irradiation.

    Silva, Cláudia Gomes; Faria, Joaquim Luís

    2009-05-01

    Titanium dioxide (TiO(2)) powder, a semiconductor material typically used as a photocatalyst, is prepared following an acid-catalyzed sol-gel method starting from titanium isopropoxide. The xerogel calcination temperature is used to control surface and morphological properties of the material. Materials are extensively characterized by spectroscopic, micrographic and calorimetric techniques. The different TiO(2) catalysts are used in the visible-light-driven photocatalytic degradation of clofibric acid, a lipid regulator drug. The photoefficiency of TiO(2) catalysts, quantified in terms of kinetic rate constant, total organic carbon removal and initial quantum yield, increases with calcination temperature up to 673 K. A further increase in the calcination temperature leads to a decline in the photoefficiency of the catalysts, which is associated with the phase transformation from anatase to rutile concomitant with an increase in crystallite dimensions. The photochemical and photocatalytic oxidation of clofibric acid follows a pseudo-first order kinetic rate law. 4-Chlorophenol, isobutyric acid, hydroquinone, benzoquinone and 4-chlorocatechol are detected as main intermediates.

  17. Protonated graphitic carbon nitride coated metal-organic frameworks with enhanced visible-light photocatalytic activity for contaminants degradation

    Huang, Jie; Zhang, Xibiao; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Wen, Congcong

    2018-05-01

    Most of the reported composites of g-C3N4/metal-organic frameworks (MOFs) were obtained via exfoliation of g-C3N4 and wrapping the nanosheets on MOFs with weak interaction. In this work, chemical protonation of g-C3N4 and dip-coating was adopted as a feasible pathway to achieve the real combination of g-C3N4 derivatives with a familiar MOF material MIL-100(Fe). Structural, chemical and photophysical properties of the novel hybrid photocatalysts were characterized and compared to those of the parent materials. It was verified that the protonated g-C3N4 species of appropriate content were uniformly coated along the frameworks of MIL-100(Fe) with strong interaction. The optimal materials maintained the intact framework structure, surface property and porosity of MIL-100(Fe), as well as the inherent structural units and physicochemical properties of C3N4. In comparison to the parent materials, the protonated g-C3N4 coated MIL-100(Fe) materials exhibited enhanced photocatalytic activity in degradation of rhodamine B or methylene blue dye, as well as in oxidative denitrogenation for pyridine by molecular oxygen under visible light. Introduction of protonated g-C3N4 on MOFs improved the adsorption ability for contaminant molecules. Furthermore, coating effect provided a platform for rapid photoexcited electrons transfer and superior separation of photogenerated electron-hole pairs. Photocatalytic conversion of the three contaminants followed different mechanisms.

  18. Synergistic operation of photocatalytic degradation and Fenton process by magnetic Fe3O4 loaded TiO2

    Sun, Qiong; Hong, Yong; Liu, Qiuhong; Dong, Lifeng

    2018-02-01

    The magnetic Fe3O4 loaded anatase TiO2 photocatalysts with different mass ratios were successfully synthesized by a one-step convenient calcining method. The morphology and structure analysis revealed that Fe3O4 was formed in TiO2 with very fine-grained particles. After a small amount of Fe3O4 loaded onto TiO2, the photocatalytic property enhanced obviously for the degradation of organic dye. Furthermore, the photo-Fenton-like catalysis of the iron-containing samples could also be induced after the addition of hydrogen peroxide. The apparent kinetic constant of the reaction that catalyzed by Fe-TiO2 was about 5.3 and 8.3 times of that catalyzed by TiO2 or Fe3O4 only, respectively, proving an effective synergistic contribution of the photocatalysis and Fenton reaction in the composite. Compared with Fe3O4 or free Fe3+ ions, only 13% of iron in TiO2 dissolved into acidic solution (25% for Fe3O4 and 100% for Fe3+) after the reaction, which confirmed the iron had been well immobilized onto TiO2. In addition, the extremely stable photocatalytic activity in cycling experiments proved the immobilized iron had been tightly attached onto TiO2, indicating the great potential of the catalyst for practical applications.

  19. Synergetic effect of Ag{sub 2}O as co-catalyst for enhanced photocatalytic degradation of phenol on N-TiO{sub 2}

    Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Junying [Research Center for Combustion and Environment Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Jinliang [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, Shanghai 200062 (China); Wu, Tianyang; Li, Haokun; Lei, Wenyan; Xu, Yan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, School of Physics and Materials Science, East China Normal University, Shanghai 200062 (China)

    2016-09-15

    Graphical abstract: Ag{sub 2}O/N-TiO{sub 2} composites were synthesized via a co-precipitation method for visible light photocatalytic degradation of organic pollutions with excellent photocatalytic activity. - Highlights: • Ag{sub 2}O/N-TiO{sub 2} composites were synthesized via a facile precipitation method. • Ag{sub 2}O/N-TiO{sub 2} composites exhibited enhanced photocatalytic activity. • Ag{sub 2}O acts as co-catalyst to separate the photo-generated electron-hole pairs. - Abstract: A facile precipitation method was developed to synthesize the Ag{sub 2}O/N-TiO{sub 2} composites. Their morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) and phenol under visible light irradiation were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence spectroscopy and UV–vis absorption spectroscopy, respectively. The results show that the Ag{sub 2}O/N-TiO{sub 2} composites exhibit excellent photocatalytic performance. The maximum degradation rates of MB and phenol are about 8.9 and 2.9 times that of pure N-TiO{sub 2}, respectively. The excellent photocatalytic performance is mainly ascribed to the synergetic effects of Ag{sub 2}O and N-TiO{sub 2} including the increased light absorption and the reduced electron-hole pair recombination in N-TiO{sub 2} with the presence of Ag{sub 2}O.

  20. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    Xie, Hong; Ye, Xiaoliang; Duan, Kaiyue; Xue, Muyin; Du, Yongling; Ye, Weichun; Wang, Chunming

    2015-01-01

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (k app ) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes

  1. CuAu–ZnO–graphene nanocomposite: A novel graphene-based bimetallic alloy-semiconductor catalyst with its enhanced photocatalytic degradation performance

    Xie, Hong [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Ye, Xiaoliang [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Duan, Kaiyue; Xue, Muyin; Du, Yongling; Ye, Weichun [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang, Chunming, E-mail: wangcm@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2015-07-05

    Graphical abstract: In this work, we have successfully synthesized a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite, and which behaved an enhanced photocatalytic activity. - Highlights: • A bimetallic alloy-based catalyst: CuAu–ZnO–Gr is synthesized. • CuAu–ZnO–Gr behaves an enhanced photocatalytic activity. • The detailed explanation of photocatalytic mechanism of CuAu–ZnO–Gr. - Abstract: The bimetallic alloy CuAu nanoparticles (NPs) can produce more photogenerated electrons when compared with single metal Au NPs. Moreover, graphene (Gr) sheets can help the charge separation and slow down the recombination of the electron hole pairs of ZnO. Hence, a novel graphene-based bimetallic alloy-semiconductor catalyst: CuAu–ZnO–Gr nanocomposite is synthesized. Due to the synergistic effect among CuAu NPs, ZnO nanopyramids, and Gr sheets, CuAu–ZnO–Gr behaves an enhanced photocatalytic activity for the photocatalytic degradation of synthetic colorants methyl orange (MO), methylene blue (MB), indigotin (IN), sunset yellow (SY), and tartrazine (TT) under the simulated sunlight irradiation. Furthermore, the apparent rate constants (k{sub app}) of MO, MB, IN, SY, and TT degradation are estimated respectively. In addition, the as-prepared CuAu–ZnO–Gr nanocomposite is characterized by X-ray diffraction, UV–vis spectrum, transmission electron microscopy, energy dispersive X-ray analysis (EDX), and EDX mapping. As a result of the facile synthesis route and the enhanced photocatalytic activity, this new material CuAu–ZnO–Gr can be a promising photocatalyst for the degradation of dyes.

  2. Composite nanofibers/water photosplitting and photocatalytic degradation of dairy effluent

    Kanjwal, Muzafar A.; Leung, Wallace W.F.; Chronakis, Ioannis S.

    2018-01-01

    Photocatalytic removal of Dairy effluent (DE) was studied by using TiO2-GeO2 and TiO2-CdO nanofibers (NFs), produced by electrospinning method. These NFs were characterized by SEM, TEM and XRD studies. The TiO2-GeO2 and TiO2-CdO NFs were smooth and continuous, with an average diameter of about 27...

  3. NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

    Janus Magdalena

    2015-09-01

    Full Text Available In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC.

  4. Using Ag/Ag2O/SnO2 Nanocomposites to Remove Malachite Green by a Photocatalytic Process

    Taufik, A.; Paramarta, V.; Prakoso, S. P.; Saleh, R.

    2017-03-01

    Silver/silver oxide/tin oxide nanocomposites of various weight ratios were synthesized using a microwave-assisted method. The Ag/Ag2O:SnO2 nanoparticle weight ratios used were 25:75, 50:50, and 75:25. All samples were characterized using X-ray diffraction, UV-Vis spectroscopy, Differential Scanning Calorimetry and Thermogravimetric Analysis (TGA). The Ag/Ag2O/SnO2 nanocomposites contained cubic structures provided by the Ag and Ag2O and tetragonal structures provided by the SnO2. The silver resulted in surface plasmon resonance (SPR) at a wavelength of about 435 nm. The silver oxide material was transformed into pure Ag at a temperature of about 370 °C The photocatalytic activity was tested on the degradation of malachite green (MG) from an aqueous solution. The results showed that Ag/Ag2O/SnO2 at a ratio of 50:50 exhibited the best photocatalytic performance for degrading MG under visible-light irradiation. The degradation of MG using Ag/Ag2O/SnO2 nanocomposites followed pseudo first-order kinetic reactions, and electron holes were found to be the main species acting on the degradation process.

  5. Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

    Zhang, L.; Ma, C. H.; Wang, J.; Li, S. G.; Li, Y.

    2014-12-01

    In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

  6. Solar CPC Pilot Plant Photocatalytic Degradation of Indigo Carmine Dye in Waters and Wastewaters Using Supported-TiO2: Influence of Photodegradation Parameters

    Enrico Mendes Saggioro

    2015-01-01

    Full Text Available The photocatalytic degradation of indigo carmine (IC dye in the presence of titanium dioxide under different conditions was reported. Several factors which interfere with the photodegradation efficiency as catalyst concentration, pH, initial concentration of dye, presence of inorganic anions, temperature, and the addition of hydrogen peroxide were studied under artificial irradiation with a 125 W mercury vapor lamp. Additionally, the catalyst supported on glass spheres was used for the photocatalytic degradation of the dye present in several types of waters in a CPC solar pilot plant. The photocatalytic products, carboxylic acids, and SO42- and NH4+ were followed during IC mineralization. Formate, acetate, and oxalate were detected in real MWWTP secondary effluent. The mineralization efficiency was of 42 and 21% using in suspension and supported TiO2, respectively. In order to evaluate biological effects, Eisenia andrei earthworms were used as a model organism. No significant difference (P>0.05 of weight was observed in the earthworm submitted to different concentrations of IC and its photoproducts. The photocatalytic degradation of IC on TiO2 supported on glass spheres suffered strong influence of the water matrix; nevertheless the method has the enormous advantage that it eliminates the need for the final catalyst removal step, reducing therefore the cost of treatment.

  7. Synthesize of Graphene-Tin Oxide Nanocomposite and Its Photocatalytic Properties for the Degradation of Organic Pollutants Under Visible Light.

    Shanmugam, M; Jayavel, R

    2015-09-01

    Graphene-tinoxide nanocomposite has been synthesised by coating SnO2 nanoparticles on graphene sheets by the redox reaction between graphene oxide (GO) and tin chloride. Graphene oxide was reduced to graphene and Sn2+ was oxidized to SnO2 during the redox reaction, resulting in the uniform distribution of SnO2 nanoparticles on graphene sheets. The synthesised material was characterized by XRD, SEM, AFM, FT-IR, UV-vis, TGA and Raman spectroscopic studies. SEM and AFM studies reveal the formation of wrinkled paper like structure of graphene sheets with uniform coating of SnO2 nanoparticles on either side. The strong photocatalytic degradation of Methylene orange (MO) dye was analysed using G-SnO2 nanocomposite under the visible light irradiation.

  8. Efficient Photocatalytic Degradation of Rhodamine B Dye by Aligned Arrays of Self-Assembled Hydrogen Titanate Nanotubes

    Sriparna Chatterjee

    2014-01-01

    Full Text Available We show that an aligned array of hydrothermally grown, multiwalled hydrogen titanate (H2Ti3O7 nanotubes—anchored to both faces of a metallic Ti foil—acts as an efficient photocatalyst. We studied the degradation of rhodamine B dye in the presence of the nanostructured photocatalyst under UV irradiation, by monitoring the optical absorption of the dye. Rhodamine B was chosen as a representative—and particularly harmful—industrial pollutant dye. The inner and outer diameters of the H2Ti3O7 nanotubes were 5 nm and 10 nm, respectively. The nanotube array catalyst is recyclable and structurally stable. Most importantly, it shows comparable or higher photodecomposition rate constant than those of both H2Ti3O7 nanotube powder and P-25 (Degussa. The enhanced photocatalytic performance may be ascribed to the nanotube array having a superhydrophilic surface with a high accessible surface area.

  9. Central composite rotatable design for investigation of microwave-assisted extraction of ginger (Zingiber officinale)

    Fadzilah, R. Hanum; Sobhana, B. Arianto; Mahfud, M.

    2015-12-01

    Microwave-assisted extraction technique was employed to extract essential oil from ginger. The optimal condition for microwave assisted extraction of ginger were determined by resposnse surface methodology. A central composite rotatable design was applied to evaluate the effects of three independent variables. The variables is were microwave power 400 - 800W as X1, feed solvent ratio of 0.33 -0.467 as X2 and feed size 1 cm, 0.25 cm and less than 0.2 cm as X3. The correlation analysis of mathematical modelling indicated that quadratic polynomial could be employed to optimize microwave assisted extraction of ginger. The optimal conditions to obtain highest yield of essential oil were : microwave power 597,163 W : feed solvent ratio and size of feed less than 0.2 cm.

  10. Constructing MnO{sub 2}/single crystalline ZnO nanorod hybrids with enhanced photocatalytic and antibacterial activity

    Yu, Weiwei [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Liu, Tiangui, E-mail: tianguiliu@gmail.com [College of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Cao, Shiyi; Wang, Chen [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Chen, Chuansheng, E-mail: 1666423158@qq.com [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China)

    2016-07-15

    In order to improve the photocatalytic and antibacterial activity of ZnO nanorods, ZnO nanorods decorated with MnO{sub 2} nanoparticles (MnO{sub 2}/ZnO nanorod hybrids) were prepared by using microwave assisted coprecipitation method under the influence of hydrogen peroxide, and the structure, photocatalytic activity and antibacterial property of the products were studied. Experimental results indicated that MnO{sub 2} nanoparticles are decorated on the surface of single crystalline ZnO nanorods. Moreover, the resultant MnO{sub 2}/ZnO nanorod hybrids have been proven to possess good photocatalytic and antibacterial activity, which their degradated efficiency for Rhodamin B (RhB) is twice as the pure ZnO nanorods. Enhancement for photocatalytic and antibacterial activity is mainly attributed to the low band gap energy and excellent electrochemical properties of MnO{sub 2} nanoparticles. - Graphical abstract: The MnO{sub 2}/single crystalline ZnO nanorods hybrids, which MnO{sub 2} nanoparticles are loaded on the surface of ZnO nanorods, were prepared by the step-by-step precipitation method under the assistance of ammonia and hydrogen peroxide. Display Omitted - Highlights: • MnO{sub 2}/ZnO nanorod hybrids were prepared by the step-by-step assembly method. • Single crystalline ZnO nanorods can be decorated by MnO{sub 2} nanoparticles. • MnO{sub 2}/ZnO nanorod hybrids possess good photocatalytic and antibacterial activity. • MnO{sub 2} can improve the photocatalytic activity of ZnO nanorods under visible light.

  11. In situ Sn2+-incorporation synthesis of titanate nanotubes for photocatalytic dye degradation under visible light illumination

    Tsai, Chien-Cheng; Chen, Liang-Che; Yeh, Te-Fu; Teng, Hsisheng

    2013-01-01

    Highlights: ► Sn 2+ ions sensitize titanate nanotubes for photocatalysis under visible-light illumination. ► The Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanates. ► The presence of Sn 2+ lifts the valence band of titanate nanotubes by approximately 0.9 eV. ► The doped Sn 2+ sites are active in donating photo-induced charges to dye degradation. - Abstract: Sn 2+ -incorporated titanate nanotubes, prepared by washing a layered sodium titanate with a SnCl 2 solution for tube formation, exhibit noticeable photocatalytic activity under visible light irradiation. This in situ synthesis results in a Sn/Ti ratio of approximately 0.6. Because of the introduction of Sn 2+ ions, the Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanate nanotubes. Optical absorption analysis shows that Sn doping reduces the bandgap of titanate nanotubes from 3.5 to 2.6 eV. Oxidation of the Sn 2+ -incorporated titanate nanotubes leads to oxidation of Sn 2+ to Sn 4+ , hence, widening the bandgap. Under visible light irradiation, Sn 2+ -incorporated titanate nanotubes effectively degrade methylene blue in an aqueous solution, whereas the bare titanate nanotubes exhibit substantially lower photocatalytic activity. Photoluminescence analysis demonstrates that the induced charges from excitation of the Sn 2+ ions tend to be relaxed through chemical interactions, rather than irradiative recombination.

  12. Hydrothermal synthesis of coral-like Au/ZnO catalyst and photocatalytic degradation of Orange II dye

    Chen, P.K.; Lee, G.J.; Davies, S.H.; Masten, S.J.; Amutha, R.; Wu, J.J.

    2013-01-01

    Highlights: ► Coral-like Au/ZnO was successfully prepared using green synthetic method. ► Gold nanoparticles were deposited on the ZnO structure using NaBH 4 and β-D-glucose. ► Coral-like Au/ZnO exhibited superior photocatalytic activity to degrade Orange II. - Abstract: A porous coral-like zinc oxide (c-ZnO) photocatalyst was synthesized by the hydrothermal method. The coral-like structure was obtained by precipitating Zn 4 (CO 3 )(OH) 6 ·H 2 O (ZnCH), which forms nanosheets that aggregate together to form microspheres with the coral-like structure. X-ray diffraction (XRD) studies indicate that after heating at 550 °C the ZnCH microspheres can be converted to ZnO microspheres with a morphology similar to that of ZnCH microspheres. Thermogravimetric analysis (TGA) shows this conversion takes place at approximately 260 °C. A simple electrostatic self-assembly method has been employed to uniformly disperse Au nanoparticles (1 wt.%) on the ZnO surface. In this procedure β-D-glucose was used to stabilize the Au nanoparticles. Scanning electron microscope images indicate that the diameter of coral-like ZnO microspheres (c-ZnO) is about 8 μm. X-ray diffraction reveals that the ZnO is highly crystalline with a wurtzite structure and the Au metallic particles have an average size of about 13 nm. X-ray photoelectron spectroscopic (XPS) studies have confirmed the presence of ZnO and also showed that the Au is present in the metallic state. The photocatalytic degradation of Orange II dye, with either ultraviolet or visible light, is faster on Au/c-ZnO than on c-ZnO

  13. Sn-doped ZnO nanopetal networks for efficient photocatalytic degradation of dye and gas sensing applications

    Bhatia, Sonik, E-mail: sonikbhatia@gmail.com [Department of Physics, Kanya Maha Vidyalaya, Vidyalaya Marg, Jalandhar, 144004 (India); Verma, Neha [Department of Physics, Kanya Maha Vidyalaya, Vidyalaya Marg, Jalandhar, 144004 (India); Bedi, R.K. [Satyam Institute of Engineering and Technology, Amritsar, 143107, Punjab (India)

    2017-06-15

    sensitivity and photocatalytic activity. The sensing performance showed 5% volume of ethanol and acetone and gases could be detected with sensitivity of 86.80% and 84.40% respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory. Sn–ZnO was used as photocatalyst for degradation of DR-31 dye. Optimum concentration of prepared nanoparticles (2.0 at. wt%) exhibits complete degradation of dye only in 60 min under UV irradiation.

  14. Photocatalytic degradation of malathion using Zn2+-doped TiO2 nanoparticles: statistical analysis and optimization of operating parameters

    Nasseri, Simin; Omidvar Borna, Mohammad; Esrafili, Ali; Rezaei Kalantary, Roshanak; Kakavandi, Babak; Sillanpää, Mika; Asadi, Anvar

    2018-02-01

    A Zn2+-doped TiO2 is successfully synthesized by a facile photodeposition method and used in the catalytic photo-degradation of organophosphorus pesticide, malathion. The obtained photocatalysts are characterized in detail by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD results confirm the formation of the anatase and rutile phases for the Zn2+-doped TiO2 nanoparticles, with crystallite sizes of 12.9 nm. Zn2+-doped TiO2 that was synthesized by 3.0%wt Zn doping at 200 °C exhibited the best photocatalytic activity. 60 sets of experiments were conducted using response surface methodology (RSM) by adjusting five operating parameters, i.e. initial malathion concentration, catalyst dose, pH, reaction time at five levels and presence or absence of UV light. The analysis revealed that all considered parameters are significant in the degradation process in their linear terms. The optimum values of the variables were found to be 177.59 mg/L, 0.99 g/L, 10.99 and 81.04 min for initial malathion concentration, catalyst dose, pH and reaction time, respectively, under UV irradiation (UV ON). Under the optimized conditions, the experimental values of degradation and mineralization were 98 and 74%, respectively. Moreover, the effects of competing anions and H2O2 on photocatalyst process were also investigated.

  15. Optimization of degradation of Reactive Black 5 (RB5) and electricity generation in solar photocatalytic fuel cell system.

    Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusoff, NikAthirah; Lee, Sin-Li; Yusuf, Sara Yasina

    2017-10-01

    The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their V oc , J sc and P max . The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Biphasic TiO2 nanoparticles decorated graphene nanosheets for visible light driven photocatalytic degradation of organic dyes

    Alamelu, K.; Raja, V.; Shiamala, L.; Jaffar Ali, B. M.

    2018-02-01

    We present characterization of biphasic TiO2 nanoparticles and its graphene nanocomposite synthesized by cost effective, hydrothermal method. The structural properties and morphology of the samples were characterized by series of spectroscopic and microscopic techniques. Introducing high surface area graphene could suppress the electron hole pair recombination rate in the nanocomposite. Further, the nanocomposite shows red-shift of the absorption edge and contract of the band gap from 2.98 eV to 2.85 eV. We have characterized its photocatalytic activity under natural sunlight and UV filtered sunlight irradiation. Data reveal graphene-TiO2 composite exhibit about 15 and 3.5 folds increase in degradability of Congo red and Methylene Blue dyes, respectively, comparison to pristine TiO2. This underscores the marginal effect of UV component of sunlight on the degradation ability of composite, implying its increased efficiency in harnessing visible region of solar spectrum. We have thus developed a visible light active graphene composite catalyst that can degrade both cationic and anionic dyes and making it potentially useful in environmental remediation and water splitting applications, under direct sunlight.

  17. Photocatalytic behaviour of CdS/ZnS nanocomposite for dye degradation in presence of visible light

    Patil, B. N. [Department of Physics, Shri Datta Meghe Polytechnic, Nagpur, M.S. (India); Acharya, S. A., E-mail: saha275@yahoo.com [Department of Physics, Rastrasant Tukdoji Maharaj Nagpur University, Nagpur-440033 (India)

    2016-05-06

    In the present work ZnS-CdS composite was prepared by hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD) to confirm formation of nano particles, Scanning electron microscopy (SEM) images exhibit nanoscale dimensions of as synthesized individual phases. UV/VIS spectra were recorded for evaluation of photophysical properties. The composite was explored as photocatalysts to study dye degradation using methylene blue in aqueous slurry under irradiation of 663 nm wavelength and congo red under irradiation of 493 nm wavelength. Under the same conditions the photocatalytic activity of the individual phases ZnS and CdS were also examined. The ZnS-CdS composite is found in enhancing the rate of photo degradation of toxic dyes as compare to ZnS and CdS individually in presence of visible light. This ZnS based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst in visible light.

  18. MoS{sub 2}–GO nanocomposites synthesized via a hydrothermal hydrogel method for solar light photocatalytic degradation of methylene blue

    Ding, Yong; Zhou, Yifeng, E-mail: yifengzhou@126.com; Nie, Wangyan; Chen, Pengpeng, E-mail: chenpp@ahu.edu.cn

    2015-12-01

    Graphical abstract: - Highlights: • The molybdenum disulfide–graphene oxide (MoS{sub 2}–GO) nanocomposite was synthesized via a one-step hydrothermal hydrogel method. • MoS{sub 2} and GO were composited fairly well in the obtained nanocomposites. • The electrons–hole pair recombination rate of MoS{sub 2} was greatly reduced via compositing with graphene. • The MoS{sub 2}–GO nanocomposite exhibited excellent photocatalytic performance for the degradation of methylene blue under solar light irradiation. - Abstract: In this work, molybdenum disulfide–graphene oxide (MoS{sub 2}–GO) composite hydrogel was prepared via a one-step hydrothermal method. The morphology and structure of the as-prepared hydrogels with different proportions of MoS{sub 2} and GO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, electrochemical impedance spectra and UV–vis absorption spectroscopy. The photocatalytic performance of MoS{sub 2}–GO nanocomposites was studied toward the degradation of methylene blue (MB). Results showed that the MoS{sub 2}–GO nanocomposites exhibited improved photocatalytic activities in the degradation of MB with a maximum degradation rate of 99% under solar lights irradiation within 60 min. The synthesized MoS{sub 2}–GO composite hydrogel possesses great potential toward the development of newly synthesizable catalysts in the field of organic degradation in water.

  19. Popcorn balls-like ZnFe{sub 2}O{sub 4}-ZrO{sub 2} microsphere for photocatalytic degradation of 2,4-dinitrophenol

    Chen, Xi [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Liu, Yutang [Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Xia, Xinnian, E-mail: xnxia@hnu.edu.cn [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Wang, Longlu [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2017-06-15

    Highlights: • Popcorn balls-like microsphere photocatalyst. • High photocatalytic activity toward 2,4-DNP degradation. • Degradation kinetics, mechanism, active species were analyzed. • Excellent stable recycling performance. - Abstract: In this paper, novel popcorn balls-like ZnFe{sub 2}O{sub 4}-ZrO{sub 2} composite microspheres were successfully fabricated by a simple hydrothermal method. The morphology, structure and optical property of the microspheres were characterized. The microspheres were used as the photocatalysts to degrade 2,4-dinitrophenol, and exhibited superior photocatalytic performance. Under simulated solar visible light irradiation, the degradation rate of ZnFe{sub 2}O{sub 4}-ZrO{sub 2} photocatalyst (mass ratio of ZnFe{sub 2}O{sub 4}/ZrO{sub 2} = 2:1) was almost 7.4 and 2.4 times higher than those of pure ZnFe{sub 2}O{sub 4} and ZrO{sub 2}. The enhancement could attribute to stronger light absorption, lower carrier recombination and multi-porous structure of the microspheres. Moreover, the popcorn balls-like photocatalysts can be easily separated, because of the magnetism of the samples. After five times runs, the photocatalyst still showed 90% of its photocatalytic degradation efficiency. This work demonstrated a good prospect for removing organic pollutants in water.

  20. Ag3PO4/ZnO: An efficient visible-light-sensitized composite with its application in photocatalytic degradation of Rhodamine B

    Liu, Wei; Wang, Mingliang; Xu, Chunxiang; Chen, Shifu; Fu, Xianliang

    2013-01-01

    Graphical abstract: The free OH radicals generated in the VB of ZnO play the primary role in the visible-light photocatalytic degradation of RhB in Ag 3 PO 4 /ZnO system. The accumulated electrons in the CB of Ag 3 PO 4 can be transferred to O 2 adsorbed on the surface of the composite semiconductors and H 2 O 2 yields. H 2 O 2 reacts with electrons in succession to produce active ·OH to some extent. Display Omitted Highlights: ► Efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites were successfully prepared. ► Effect of Ag 3 PO 4 content on the catalytic activity of Ag 3 PO 4 /ZnO is studied in detail. ► Rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of Ag 3 PO 4 . ► The active species in RhB degradation are examined by adding a series of scavengers. ► Visible light degradation mechanism of RhB over Ag 3 PO 4 /ZnO is systematically studied. -- Abstract: The efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites with various weight percents of Ag 3 PO 4 were prepared by a facile ball milling method. The photocatalysts were characterized by XRD, DRS, SEM, EDS, XPS, and BET specific area. The ·OH radicals produced during the photocatalytic reaction was detected by the TA–PL technique. The photocatalytic property of Ag 3 PO 4 /ZnO was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. Significantly, the results revealed that the photocatalytic activity of the composites was much higher than that of pure Ag 3 PO 4 and ZnO. The rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of single-phase Ag 3 PO 4 . The optimal percentage of Ag 3 PO 4 in the composite is 3.0 wt.%. It is proposed that the ·OH radicals produced in the valence band of ZnO play the leading role in the photocatalytic degradation of Rhodamine B by Ag 3 PO 4 /ZnO systems under visible light irradiation.

  1. Fabrication of TiO2/MoS2@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    Zhang, Weiping; Xiao, Xinyan; Zheng, Lili; Wan, Caixia

    2015-01-01

    Graphical abstract: A novel approach was developed for fabrication of TiO 2 /MoS 2 @zeolite photocatalyst using bulk MoS 2 as a photosensitizer and zeolite as carrier. The as-prepared TiO 2 /MoS 2 @zeolite composite exhibited excellent photocatalytic performance for degradation of methyl orange under visible-light irradiation. - Highlights: • Ultrasound-exfoliation and hydrothermal reforming technique were employed for generating nano-MoS 2 from micro-MoS 2 . • The embedded sensitizer composite mode of (TiO 2 /MoS 2 /TiO 2 ) was used in the fabrication of TiO 2 /MoS 2 @zeolite composite photocatalyst. • The photocatalytic mechanism of TiO 2 /MoS 2 @zeolite photocatalyst was presented. - Abstract: TiO 2 /MoS 2 @zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl 4 as Ti source, MoS 2 as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM–EDS, TEM, XPS, UV–vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO 2 /MoS 2 @zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir–Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (k app ) (2.304 h −1 ) is higher than that of Degussa P25 (0.768 h −1 ); (3) the heterostructure consisted of zeolite, MoS 2 and TiO 2 nanostructure could provide synergistic effect for degradation

  2. Fabrication of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    Zhang, Weiping; Xiao, Xinyan, E-mail: cexyxiao@scut.edu.cn; Zheng, Lili; Wan, Caixia

    2015-12-15

    Graphical abstract: A novel approach was developed for fabrication of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst using bulk MoS{sub 2} as a photosensitizer and zeolite as carrier. The as-prepared TiO{sub 2}/MoS{sub 2}@zeolite composite exhibited excellent photocatalytic performance for degradation of methyl orange under visible-light irradiation. - Highlights: • Ultrasound-exfoliation and hydrothermal reforming technique were employed for generating nano-MoS{sub 2} from micro-MoS{sub 2}. • The embedded sensitizer composite mode of (TiO{sub 2}/MoS{sub 2}/TiO{sub 2}) was used in the fabrication of TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalyst. • The photocatalytic mechanism of TiO{sub 2}/MoS{sub 2}@zeolite photocatalyst was presented. - Abstract: TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl{sub 4} as Ti source, MoS{sub 2} as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM–EDS, TEM, XPS, UV–vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO{sub 2}/MoS{sub 2}@zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir–Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (k{sub app}) (2.304 h{sup −1}) is higher than that of Degussa P25 (0.768 h{sup −1}); (3) the heterostructure

  3. Synthesis of benzamides by microwave assisted ring opening of less reactive dimethylaminobenzylidene oxazolone

    Saurabh C. Khadse

    2017-02-01

    Full Text Available This paper presents the synthesis of some benzamide compounds (B1–B10 by microwave-assisted ring opening of 4-(4-dimethylaminobenzylidene-2-phenyl-5-oxazolone (AZ4. By conventional synthesis involving heating, it was found difficult to obtain ring-opened products, probably due to poor tendency of the carbonyl carbon (C5 of AZ4 to undergo nucleophilic attack by mono/or disubstituted anilines. Microwave assisted reactions were easy to perform, have reduced the reaction time and produced good yields.

  4. Microwave-assisted one-step synthesis of acetate-capped NaYF4

    Reddy, Kumbam Lingeshwar; Prabhakar, Neeraj; Arppe, Riikka

    2017-01-01

    Acetate-capped hydrophilic cubic phase NaYF4:Yb/Er upconversion nanophosphors were effectively synthesized in a single step employing a facile microwave-assisted synthesis route by applying relatively low temperatures in a short span of time compared to the conventional synthetic methods. The nan......Acetate-capped hydrophilic cubic phase NaYF4:Yb/Er upconversion nanophosphors were effectively synthesized in a single step employing a facile microwave-assisted synthesis route by applying relatively low temperatures in a short span of time compared to the conventional synthetic methods...

  5. Fabrication of Z-scheme Ag3PO4/MoS2 composites with enhanced photocatalytic activity and stability for organic pollutant degradation

    Zhu, Chaosheng; Zhang, Lu; Jiang, Bo; Zheng, Jingtang; Hu, Ping; Li, Sujuan; Wu, Mingbo; Wu, Wenting

    2016-01-01

    Highlights: • Ag 3 PO 4 /MoS 2 composite photocatalysts were prepared by precipitation method. • The composites showed enhanced visible-light photocatalytic activity. • The photocorrosion of Ag 3 PO 4 was inhibited due to the introduction of MoS 2 . • Z-scheme mechanism was proposed to explain the enhanced photoactivity. - Abstract: In this study, highly efficient visible-light-driven Ag 3 PO 4 /MoS 2 composite photocatalysts with different weight ratios of MoS 2 were prepared via the ethanol-water mixed solvents precipitation method and characterized by ICP, XRD, HRTEM, FE-SEM, BET, XPS, UV–vis DRS and PL analysis. Under visible-light irradiation, Ag 3 PO 4 /MoS 2 composites exhibit excellent photocatalytic activity towards the degradation of organic pollutants in aqueous solution. The optimal composite with 0.648 wt% MoS 2 content exhibits the highest photocatalytic activity, which can degrade almost all MB under visible-light irradiation within 60 min. Recycling experiments confirmed that the Ag 3 PO 4 /MoS 2 catalysts had superior cycle performance and stability. The photocatalytic activity enhancement of Ag 3 PO 4 /MoS 2 photocatalysts can be mainly ascribed to the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of Ag 3 PO 4 , Ag and MoS 2 , in which Ag particles act as the charge separation center. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag 3 PO 4 by transferring the photogenerated electrons of Ag 3 PO 4 to MoS 2 . The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts could be obtained from the active species trapping experiments and the photoluminescence technique.

  6. Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO2/SiO2 photocatalyst using a fluidized bed reactor.

    Zhang, Maolin; An, Taicheng; Fu, Jiamo; Sheng, Guoying; Wang, Xinming; Hu, Xiaohong; Ding, Xuejun

    2006-06-01

    An adsorptive silica-supported titania photocatalyst TiO(2)/SiO(2) was prepared by using nanosized titania (anatase) immobilized on silica gel by the sol-gel technique with the titanium tetra isopropoxide as the main raw material and acetic acid as the acid catalyst. Meanwhile the structure and properties of the TiO(2)/SiO(2) photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, and BET. Gas-solid heterogeneous photocatalytic decomposition of four carbonyl compounds mixture at low concentration levels over ultraviolet irradiated TiO(2)/SiO(2) photocatalyst were carried out with high degradation efficiencies in a coaxial triple-cylinder-type fluidized bed photocatalytic reactor, which provided efficient continuous contact of ultraviolet photons, silica-supported titania photocatalyst, and gaseous reactants. Experimental results showed that the photocatalyst had a high adsorption performance and a good photocatalytic activity for four carbonyl compounds mixture. Some factors influencing the photocatalytic decomposition of the mixed carbonyl compounds, i.e. the gas flowrate, relative humidity, concentration of oxygen, and illumination time, were discussed in detail. It is found that the photocatalytic reaction rate of four carbonyl compounds decreased in this order: propionaldehyde, acetone, acetaldehyde and formaldehyde.

  7. Synthesis of BiVO4-GO-PVDF nanocomposite: An excellent, newly designed material for high photocatalytic activity towards organic dye degradation by tuning band gap energies

    Biswas, Md Rokon Ud Dowla; Oh, Won-Chun

    2018-06-01

    BiVO4-GO-PVDF (PVDF = Polyvinylidene Difluoride) photocatalyst is successfully synthesized by ultrasonication method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. Morphology of BiVO4-GO-PVDF looks like a human embryo embedded inside an amniotic sac. Photocatalytic performance of BiVO4-GO-PVDF for decolorization of methylene blue is investigated. BiVO4-GO-PVDF system reveals enhanced photocatalytic activity degradation of methylene blue (MB), Rhodamine B (RhB) & Safranin-O (SO) in water under visible light irradiation as compared to the pure BiVO4 catalyst, BiVO4 & PTFE decorated on the graphene sheet. The experimental result reveals that the covering of graphene sheets in this composite catalyst enhances photocatalytic performance under visible light. This enhanced activity is mainly attributed to effective quenching of the photogenerated electron-hole pairs confirmed by photoluminescence spectra. Trapping experiments of radicals and holes were conducted to detect reactive species generated in the photocatalytic system, experimental results revealed that direct hole oxidation reaction is obviously dominant during photocatalytic reactions on the BiVO4-GO-PVDF system.

  8. Facile synthesis of bird's nest-like TiO2 microstructure with exposed (001) facets for photocatalytic degradation of methylene blue

    Zhang, Guozhong; Zhang, Shuqu; Wang, Longlu; Liu, Ran; Zeng, Yunxiong; Xia, Xinnian; Liu, Yutang; Luo, Shenglian

    2017-01-01

    The scrupulous design of hierarchical structure and highly active crystal facets exposure is essential for the creation of photocatalytic system. However, it is still a big challenge for scrupulous design of TiO2 architectures. In this paper, bird's nest-like anatase TiO2 microstructure with exposed highly active (001) surface has been successfully synthesized by a facile one-step solvothermal method. Methylene blue (MB) is chosen as a model pollutant to evaluate photocatalytic activity of as-obtained TiO2 samples. The results show that the photocatalytic activity of the bird's nest-like sample is more excellent than P25 in the degradation of MB due to high specific surface area and highly active (001) crystal facets exposure when tested under simulated solar light. Besides, it can be readily separated from the photocatalytic system by sedimentation after photocatalytic reaction, which is a significant advantage against conventional powder photocatalyst. The bird's nest-like microspheres with novel structure may have potential application in photocatalysis and other fields.

  9. Photocatalytic Degradation of Methylene Blue Using TiO2 Impregnated Diatomite

    Zuo, Ranfang; Du, Gaoxiang; Zhang, Weiwei; Liu, Lianhua; Liu, Yanming; Mei, Lefu; Li, Zhaohui

    2014-01-01

    Nano-TiO2 showed a good catalytic activity, but it is easy to agglomerate, resulting in the reduction or even complete loss of photocatalytic activity. The dispersion of TiO2 particles on porous materials was a potential solution to this problem. Diatomite has high specific surface and absorbability because of its particular shell structure. Thus, TiO2/diatomite composite, prepared by loading TiO2 on the surface of diatomite, was a good photocatalyst, through absorbing organic compounds with ...

  10. Enhanced photocatalytic degradation of norfloxacin in aqueous Bi{sub 2}WO{sub 6} dispersions containing nonionic surfactant under visible light irradiation

    Tang, Lin, E-mail: tanglin@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Wang, Jiajia [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

    2016-04-05

    Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi{sub 2}WO{sub 6} dispersions under visible light irradiation (400–750 nm). • Cu{sup 2+} (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi{sub 2}WO{sub 6} was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi{sub 2}WO{sub 6} dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi{sub 2}WO{sub 6} surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

  11. Microwave-assisted synthesis and properties of a series of poly(2-alkyl-2-oxazoline)s

    Hoogenboom, R.; Fijten, M.W.M.; Thijs, H.M.L.; Lankvelt, van B.M.; Schubert, U.S.

    2005-01-01

    Microwave-assisted organic synthesis is a quickly expanding field of research. The fast non-contact (super)heating of the reaction mixtures has already resulted in many examples of increased reaction rates and improved yields. However, the number of investigations focusing on microwave-assisted

  12. Electrospun NiO, ZnO and composite NiO–ZnO nanofibers/photocatalytic degradation of dairy effluent

    Kanjwal, Muzafar Ahmad; Chronakis, Ioannis S.; Barakat, Nasser A.M.

    2015-01-01

    Among the food wastes, the dairy effluent (DE) is considered to be the most polluting one because of the large volume of wastewater generated and its high organic load. Photocatalytic degradation of DE and organic dye methylene blue (MB) was studied using Zinc oxide nanofibers (ZnO NFs), Nickel....... The significant enhancement of degradation in the composite ZnO–NiO NFs is attributed to the photoactivity of material under visible light irradiation. The composite ZnO–NiO NFs eliminated 40% of DE and 65% of MB dye, after 1h and maximum degradation of 80% DE after 3h and 100% MB dye after 90min. Overall...

  13. Investigation on Parameters Affecting the Effectiveness of Photocatalytic Functional Coatings to Degrade NO: TiO2 Amount on Surface, Illumination, and Substrate Roughness

    J. Hot

    2017-01-01

    Full Text Available This paper deals with the degradation of NO by photocatalytic oxidation using TiO2-based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored to evaluate their influence on photocatalysis efficiency: TiO2 dry matter content applied to the surface, nature of the substrate, and illumination conditions (UV and visible light. This article points out the different behaviors between three kinds of substrates which are common building materials: normalized mortar, denser mortar, and commercial wood. The illumination conditions are of great importance in the photocatalytic process with experiments under UV light showing the best results. However, a significant decrease in NO concentration under visible light is also observed provided that the TiO2 dry matter content on the surface is high enough. The nature of the substrate plays an important role in the photocatalytic activity with rougher substrates being more efficient to degrade NO. However, limiting the roughness of the substrate seems to be of utmost interest to obtain the highest exposed surface area and thus the optimal photocatalytic efficiency. A higher roughness promotes the surface contact between TiO2 and NO but does not necessarily increase the photochemical oxidation.

  14. Hydrothermal synthesis of B-doped Bi2MoO6 and its high photocatalytic performance for the degradation of Rhodamine B

    Wang, Min; Han, Jin; Guo, Pengyao; Sun, Mingzhi; Zhang, Yu; Tong, Zhu; You, Meiyan; Lv, Chunmei

    2018-02-01

    B-doped Bi2MoO6 photocatalysts have been synthesized by a hydrothermal method using HBO3 as the doping source and the effect of B doping content on Bi2MoO6 structure and performance was studied. The samples were characterized with XPS, XRD, SEM, BET, UV-Vis DRS, and PL. The photocatalytic activity was evaluated by photocatalytic degradation of Rhodamine B (RhB) under visible light (λ ≥ 420 nm). The results show that all samples are orthorhombic structure. Doping Bi2MoO6 with B increases the amount of Bi5+ and oxygen vacancies, which led to stronger absorption in visible light region and lower band gap energy of the B-doped Bi2MoO6 but had little impact on morphology. B doping significantly improves the photocatalytic activity of Bi2MoO6 and the highest photocatalytic degradation rate is 89% when the initial molar ratio of B to Bi is 0.01.

  15. High photocatalytic degradation activity of the polyvinyl chloride (PVC)-vitamin C (VC)-TiO{sub 2} nano-composite film

    Yang Changjun; Gong Chuqing; Peng Tianyou [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Deng Kejian [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan 430074 (China); Zan Ling, E-mail: irlab@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2010-06-15

    A novel photodegradable polyvinyl chloride (PVC)-vitamin C (VC)-TiO{sub 2} nano-composite film was prepared by embedding VC modified nano-TiO{sub 2} photocatalyst into the commercial PVC plastic. The solid-phase photocatalytic degradation behavior of PVC-VC-TiO{sub 2} nano-composite film under UV light irradiation was investigated and compared with those of the PVC-TiO{sub 2} film and the pure PVC film, with the aid of UV-Vis spectroscopy, scanning electron microscopy (SEM), weight loss monitoring, and X-ray diffraction spectra (XRD). The results show that PVC-VC-TiO{sub 2} nano-composite film has a high photocatalytic activity; the photocatalytic degradation rate of it is two times higher than that of PVC-TiO{sub 2} film and fifteen times higher than that of pure PVC film. The optimal mass ratio of VC to TiO{sub 2} is found to be 0.5. The mechanism of enhancing photocatalytic activity is attributed to the formation of a Ti{sup IV}-VC charge-transfer complex with five-member chelate ring structure and a rapid photogenerated charge separation is thus achieved.

  16. High photocatalytic degradation activity of the polyvinyl chloride (PVC)-vitamin C (VC)-TiO2 nano-composite film

    Yang Changjun; Gong Chuqing; Peng Tianyou; Deng Kejian; Zan Ling

    2010-01-01

    A novel photodegradable polyvinyl chloride (PVC)-vitamin C (VC)-TiO 2 nano-composite film was prepared by embedding VC modified nano-TiO 2 photocatalyst into the commercial PVC plastic. The solid-phase photocatalytic degradation behavior of PVC-VC-TiO 2 nano-composite film under UV light irradiation was investigated and compared with those of the PVC-TiO 2 film and the pure PVC film, with the aid of UV-Vis spectroscopy, scanning electron microscopy (SEM), weight loss monitoring, and X-ray diffraction spectra (XRD). The results show that PVC-VC-TiO 2 nano-composite film has a high photocatalytic activity; the photocatalytic degradation rate of it is two times higher than that of PVC-TiO 2 film and fifteen times higher than that of pure PVC film. The optimal mass ratio of VC to TiO 2 is found to be 0.5. The mechanism of enhancing photocatalytic activity is attributed to the formation of a Ti IV -VC charge-transfer complex with five-member chelate ring structure and a rapid photogenerated charge separation is thus achieved.

  17. A bamboo-inspired hierarchical nanoarchitecture of Ag/CuO/TiO_2 nanotube array for highly photocatalytic degradation of 2,4-dinitrophenol

    Zhang, Xuhong; Wang, Longlu; Liu, Chengbin; Ding, Yangbin; Zhang, Shuqu; Zeng, Yunxiong; Liu, Yutang; Luo, Shenglian

    2016-01-01

    Highlights: • Bamboo-like architecture of ternary photocatalyst. • High simulated solar light photocatalytic activity. • Integration of p-n heterojunction and Schottky junction. • Excellent stable recycling performance. - Abstract: The optimized geometrical configuration of muitiple active materials into hierarchical nanoarchitecture is essential for the creation of photocatalytic degradation system that can mimic natural photosynthesis. A bamboo-like architecture, CuO nanosheets and Ag nanoparticles co-decorated TiO_2 nanotube arrays (Ag/CuO/TiO_2), was fabricated by using simple solution-immersion and electrodeposition process. Under simulated solar light irradiation, the 2,4-dinitrophenol (2,4-DNP) photocatalytic degradation rate over Ag/CuO/TiO_2 was about 2.0, 1.5 and 1.2 times that over TiO_2 nanotubes, CuO/TiO_2 and Ag/TiO_2, respectively. The enhanced photocatalytic activity of ternary Ag/CuO/TiO_2 photocatalyst was ascribed to improved light absorption, reduced carrier recombination and more exposed active sites. Moreover, the excellent stability and reliability of the Ag/CuO/TiO_2 photocatalyst demonstrated a promising application for organic pollutant removal from water.

  18. A bamboo-inspired hierarchical nanoarchitecture of Ag/CuO/TiO{sub 2} nanotube array for highly photocatalytic degradation of 2,4-dinitrophenol

    Zhang, Xuhong; Wang, Longlu [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Ding, Yangbin; Zhang, Shuqu; Zeng, Yunxiong [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Liu, Yutang, E-mail: liuyutang@126.com [Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Luo, Shenglian [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2016-08-05

    Highlights: • Bamboo-like architecture of ternary photocatalyst. • High simulated solar light photocatalytic activity. • Integration of p-n heterojunction and Schottky junction. • Excellent stable recycling performance. - Abstract: The optimized geometrical configuration of muitiple active materials into hierarchical nanoarchitecture is essential for the creation of photocatalytic degradation system that can mimic natural photosynthesis. A bamboo-like architecture, CuO nanosheets and Ag nanoparticles co-decorated TiO{sub 2} nanotube arrays (Ag/CuO/TiO{sub 2}), was fabricated by using simple solution-immersion and electrodeposition process. Under simulated solar light irradiation, the 2,4-dinitrophenol (2,4-DNP) photocatalytic degradation rate over Ag/CuO/TiO{sub 2} was about 2.0, 1.5 and 1.2 times that over TiO{sub 2} nanotubes, CuO/TiO{sub 2} and Ag/TiO{sub 2}, respectively. The enhanced photocatalytic activity of ternary Ag/CuO/TiO{sub 2} photocatalyst was ascribed to improved light absorption, reduced carrier recombination and more exposed active sites. Moreover, the excellent stability and reliability of the Ag/CuO/TiO{sub 2} photocatalyst demonstrated a promising application for organic pollutant removal from water.

  19. Fe-N co-doped SiO2@TiO2 yolk-shell hollow nanospheres with enhanced visible light photocatalytic degradation

    Wan, Hengcheng; Yao, Weitang; Zhu, Wenkun; Tang, Yi; Ge, Huilin; Shi, Xiaozhong; Duan, Tao

    2018-06-01

    SiO2@TiO2 yolk@shell hollow nanospheres (STNSs) is considered as an outstanding photocatalyst due to its tunable structure and composition. Based on this point, we present an unprecedentedly excellent photocatalytic property of STNSs toward tannic acid via a Fe-N co-doped strategy. Their morphologies, compositions, structure and properties are characterized. The Fe-N co-doped STNSs formed good hollow yolk@shell structure. The results show that the energy gap of the composites can be downgraded to 2.82 eV (pure TiO2 = 3.2 eV). Photocatalytic degradation of tannic acid (TA, 30 mg L-1) under visible light (380 nm TiO2 nanospheres, non-doped STNSs and N-doped STNSs, the Fe-N co-doped STNSs exhibits the highest activity, which can degrade 99.5% TA into CO2 and H2O in 80 min. The probable degradation mechanism of the composites is simultaneously proposed, the band gap of STNSs becomes narrow by co-doping Fe-N, so that the TiO2 shell can stimulate electrons under visible light exposure, generate the ions of radOH and radO2- with a strong oxidizing property. Therefore this approach works is much desired for radioactive organic wastewater photocatalytic degradation.

  20. Photocatalytic degradation of nicotine in an aqueous solution using unconventional supported catalysts and commercial ZnO/TiO{sub 2} under ultraviolet radiation

    Franco, Marcela Andrea Espina de, E-mail: marcela.eq@gmail.com; Silva, William Leonardo da; Bagnara, Mônica; Lansarin, Marla Azário; Zimnoch dos Santos, João Henrique

    2014-10-01

    Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet irradiation. The experiments were carried out using commercial (ZnO, TiO{sub 2}) and non-conventional catalysts, which were prepared from industrial and laboratory waste. Two experimental designs (CCD) were performed for both commercial catalysts, and initial nicotine concentration, catalyst concentration and initial solution pH effects were studied. Then, the synthesized catalysts were tested under the optimal conditions which were found through CCDs. Using commercial catalysts, about 98% of the alkaloid was degraded by ZnO, and 88% by TiO{sub 2}, in 1 h. Among the non-conventional catalysts, the highest photocatalytic degradation (44%) was achieved using the catalyst prepared from a petrochemical industry residue. - Highlights: • The photocatalytic degradation of nicotine was studied under UV irradiation. • Commercial catalysts ZnO and TiO{sub 2} were tested using two central composite designs. • Initial nicotine concentration, catalyst concentration and pH were evaluated. • Catalysts were prepared using chemical wastes and tested at the best conditions.

  1. Fabrication of Ag{sub 2}O/TiO{sub 2} with enhanced photocatalytic performances for dye pollutants degradation by a pH-induced method

    Ren, Hai-Tao, E-mail: renhaitaomail@163.com; Yang, Qing

    2017-02-28

    Highlights: • Ag{sub 2}O/TiO{sub 2} was synthesized by a pH-induced chemical precipitation method. • Ag{sub 2}O/TiO{sub 2} showed good activities in the photocatalytic degradation of methyl orange. • Hydroxyl radicals played the predominant role in methyl orange photodegradation. - Abstract: Ag{sub 2}O/TiO{sub 2} composites synthesized in this study were applied into the photocatalytic degradation of methyl orange (MO) under UV and visible light irradiation. X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscope analysis demonstrated that Ag{sub 2}O nanoparticles were well distributed on the surface of TiO{sub 2} and the heterostructure of Ag{sub 2}O/TiO{sub 2} was formed. Compared with the pure TiO{sub 2} and Ag{sub 2}O, the 3% and 50% Ag{sub 2}O/TiO{sub 2} composite displayed much higher photocatalytic activities in MO degradation under UV and visible light irradiation, respectively. The degradation rate constant of 50% composite was 0.01508 min{sup −1} under visible light, which was almost 20.1 and 1.2 times more than that of the pure TiO{sub 2} and Ag{sub 2}O, respectively. Moreover, the formation of Ag(0) on the surface of Ag{sub 2}O under illumination contributed to the high stability of Ag{sub 2}O/TiO{sub 2} photocatalysts. It was also found that hydroxyl radicals during the photocatalytic process played the predominant role in MO degradation. The enhanced photochemical activities were attributed to the formation of the heterostructure between Ag{sub 2}O and TiO{sub 2}, the strong visible light absorption and the high separation efficiency of photogenerated electron–hole pairs resulted from the highly dispersed Ag{sub 2}O particles.

  2. Styrene–tin (IV) phosphate nanocomposite for photocatalytic degradation of organic dye in presence of visible light

    Rathore, Bhim Singh [School of Chemistry, Shoolini University, Solan 173 212, Himachal Pradesh (India); Department of Chemistry, Government P.G. College, Solan 173 212, Himachal Pradesh (India); Pathania, Deepak, E-mail: dpathania74@gmail.com [School of Chemistry, Shoolini University, Solan 173 212, Himachal Pradesh (India)

    2014-09-01

    Highlights: • Styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger was chemically prepared by simple sol–gel method at pH 0–1. • ST/TPNC exhibited higher ion exchange capacity as compared to its inorganic component. • ST/TPNC retained about 35.5% of the initial value of ion exchange capacity after heating up to 400 °C. • ST/TPNC was used as efficient photocatalyst for the degradation of MB dye from aqueous system in the presence of solar light. • The pH titrations studies confirmed the monofunctional strong cationic nature of ST/TPNC. - Abstract: Styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger was used as efficient photocatalyst for the degradation of methylene blue dye from aqueous system in the presence of solar light. ST/TPNC exhibited a high efficiency in heterogeneous photocatalytic process for the removal of MB from the water system. The degradation efficiency after 2 h illumination was 80%. The degradation of MB follows the pseudo-first-order kinetics with rate constant 0.00702 min{sup −1}. The nanocomposite ion exchanger was explored for its ion exchange capacity, pH titration, elution behavior, elution concentration and distribution coefficient (K{sub d}). ST/TPNC exhibited a higher ion exchange capacity (1.83 meg/g) compared to its inorganic counterpart (0.55 meg/g). ST/TPNC was characterized using some techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and thermogravimetric analysis (TGA)

  3. Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants.

    Agócs, Tamás Zoltán; Puskás, István; Varga, Erzsébet; Molnár, Mónika; Fenyvesi, Éva

    2016-01-01

    Advanced oxidation processes (AOPs) are considered highly competitive water treatment technologies for the removal of organic pollutants. Among AOP techniques, photocatalysis has recently been the most widely studied. Our aims were to investigate how the dispersion of nanosized titanium dioxide (nanoTiO 2 ) applied in photodegradation-based procedures can be stabilized with cyclodextrins in order to obtain a new, more efficient photocatalyst for the purification of waters polluted by xenobiotics applying UV irradiation. During our work, on the one hand, we studied the behavior and stability of nanoTiO 2 in cyclodextrin solutions. On the other hand, we used various monomer and polymer cyclodextrin derivatives, and assessed the options for nanoTiO 2 stabilization in the presence of various salts and tap water on the basis of turbidity tests. The physical stability of nanoTiO 2 dispersions is diminished in the presence of the salts found in tap water (and occurring also in surface waters and ground water) and they are precipitated immediately. This colloidal instability can be improved by cyclodextrin derivatives. Based on the results of our studies we have selected carboxymethyl β-cyclodextrin polymer (CMBCD-P) for stabilization of nanoTiO 2 dispersions. The photocatalytic degradation of methylene blue and ibuprofen as model organic pollutants in various media (distilled water, NaCl solution and tap water) has been studied using nanoTiO 2 as catalyst stabilized by CMBCD-P. CMBCD-P itself showed a catalytic effect on the UV degradation of methylene blue. In addition to enhancing the colloid stability of nanoTiO 2 CMBCD-P showed also synergistic effects in catalyzing the photodecomposition process of the dye. On the other hand, ibuprofen as a model pharmaceutical, a pollutant of emerging concern (EP), was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure of the

  4. Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

    Hazarika, Deepshikha; Karak, Niranjan, E-mail: karakniranjan@gmail.com

    2016-07-15

    Highlights: • Nitrogen containing carbon dot and carbon dot/TiO{sub 2} nanohybrid (CD@TiO{sub 2}) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO{sub 2} is found to be the best as compared to the bare TiO{sub 2}, CD and nanohybrid of TiO{sub 2} in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO{sub 2} under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO{sub 2} under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO{sub 2}) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO{sub 2} and nanohybrid of TiO{sub 2} in presence of CD (CD/TiO{sub 2}) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO{sub 2}, CD@TiO{sub 2} and CD/TiO{sub 2} were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO{sub 2} nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO{sub 2} were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO{sub 2} exhibited the most promising photocatalytic degradation of organic

  5. Single-step uncalcined N-TiO{sub 2} synthesis, characterizations and its applications on alachlor photocatalytic degradations

    Suwannaruang, Totsaporn, E-mail: totsaporn.eng.kku@gmail.com [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Wantala, Kitirote, E-mail: kitirote@kku.ac.th [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Research Center for Environmental and Hazardous Substance Management (EHSM), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand)

    2016-09-01

    Graphical abstract: - Highlights: • N-TiO{sub 2} can be synthesized on one crystal in one particle. • Surface area has been relating to performance of photocatalysts. • Energy band-gap of N-TiO{sub 2} show lower than 3.0 eV. - Abstract: The aims of this research were to synthesize nitrogen doped TiO{sub 2} (N-TiO{sub 2}) photocatalysts produced by hydrothermal technique and to test the degradation performance of alachlor by photocatalytic process under UV irradiations in the effect of aging temperature and time in the preparation process. The characterizations of synthesized TiO{sub 2} such as specific surface area, particle size, phase structure and elements were analyzed by using the Brunauer–Emmett–Teller (BET) technique, Transmission Electron Microscopy (TEM), X-ray Diffractometer (XRD) and Energy Dispersive X-ray spectrometer (EDX), respectively. The Central Composite Design (CCD) was used to design the experiment to determine the optimal condition, main effects and their interactions by using specific surface area, percent alachlor removal and observed first-order rate constant as responses. The kinetic reactions of alachlor degradation were explained by using Langmuir-Hinshelwood expression to confirm the reaction took place on the surface of photocatalyst. The results showed that the effect of aging temperatures was significant on surface area, whereas aging time was insignificant. Additionally, the square term of aging temperature and interaction term were shown significant on the specific surface area as well. The highest specific surface area from response surface at aging temperature between 150–175 °C and aging time between 6–13 h was found in a range of 100–106 m{sup 2}/g. The average particle size of TiO{sub 2} was similar to crystallite size. Therefore, it can be concluded that one particle has only one crystal. The element analysis has shown 10% of nitrogen in TiO{sub 2} structure that the energy band-gap about 2.95 eV was found

  6. Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

    Hazarika, Deepshikha; Karak, Niranjan

    2016-01-01

    Highlights: • Nitrogen containing carbon dot and carbon dot/TiO 2 nanohybrid (CD@TiO 2 ) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO 2 is found to be the best as compared to the bare TiO 2 , CD and nanohybrid of TiO 2 in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO 2 under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO 2 under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO 2 ) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO 2 and nanohybrid of TiO 2 in presence of CD (CD/TiO 2 ) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO 2 , CD@TiO 2 and CD/TiO 2 were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO 2 nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO 2 were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO 2 exhibited the most promising photocatalytic degradation of organic pollutants like benzene and phenol as well as an anthrogenic pesticide under sunlight.

  7. Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

    Tamás Zoltán Agócs

    2016-12-01

    Full Text Available Advanced oxidation processes (AOPs are considered highly competitive water treatment technologies for the removal of organic pollutants. Among AOP techniques, photocatalysis has recently been the most widely studied. Our aims were to investigate how the dispersion of nanosized titanium dioxide (nanoTiO2 applied in photodegradation-based procedures can be stabilized with cyclodextrins in order to obtain a new, more efficient photocatalyst for the purification of waters polluted by xenobiotics applying UV irradiation. During our work, on the one hand, we studied the behavior and stability of nanoTiO2 in cyclodextrin solutions. On the other hand, we used various monomer and polymer cyclodextrin derivatives, and assessed the options for nanoTiO2 stabilization in the presence of various salts and tap water on the basis of turbidity tests. The physical stability of nanoTiO2 dispersions is diminished in the presence of the salts found in tap water (and occurring also in surface waters and ground water and they are precipitated immediately. This colloidal instability can be improved by cyclodextrin derivatives. Based on the results of our studies we have selected carboxymethyl β-cyclodextrin polymer (CMBCD-P for stabilization of nanoTiO2 dispersions. The photocatalytic degradation of methylene blue and ibuprofen as model organic pollutants in various media (distilled water, NaCl solution and tap water has been studied using nanoTiO2 as catalyst stabilized by CMBCD-P. CMBCD-P itself showed a catalytic effect on the UV degradation of methylene blue. In addition to enhancing the colloid stability of nanoTiO2 CMBCD-P showed also synergistic effects in catalyzing the photodecomposition process of the dye. On the other hand, ibuprofen as a model pharmaceutical, a pollutant of emerging concern (EP, was protected by CMBCD-P against the photocatalytic degradation showing that inclusion complex formation can result in opposite effects depending on the structure

  8. A comparative approach of methylparaben photocatalytic degradation assisted by UV-C, UV-A and Vis radiations.

    Doná, Giovanna; Dagostin, João Luiz Andreoti; Takashina, Thiago Atsushi; de Castilhos, Fernanda; Igarashi-Mafra, Luciana

    2018-05-01

    Due to the widespread use of methylparaben (MEP) and its high chemical stability, it can be found in wastewater treatment plants and can act as an endocrine disrupting compound. In this study, the photocatalytic degradation and mineralization of MEP solutions were evaluated under UV-A, UV-C and Vis radiations in the presence of the photocatalyst TiO 2 . In this sense, the effects of the catalyst load, pH and MEP initial concentration were studied. Remarkably higher reaction rates and total photodegradation were achieved in systems assisted by UV-C radiation. The complete degradation was achieved after 60 min of reaction using the MEP concentration of 30 mg L -1 at pH 9 and 500 mg L -1 TiO 2 . The experimental data apparently followed a Langmuir-Hinshelwood kinetic model, which could predict 88-98% of the reaction behavior. For the best photodegradation condition, the model predicted an apparent reaction rate constant (k app ) equal to 0.0505 min -1 and an initial reaction rate of 1.5641 mg (L min) -1 . Mineralization analyses showed high removal for MEP and derived compounds from the initial solution when using UV-C after 90 min of reaction. The lower toxicity was also confirmed by in vivo tests using MEP solutions previously treated by photocatalysis.

  9. Photocatalytic degradation with immobilised TiO(2) of three selected neonicotinoid insecticides: imidacloprid, thiamethoxam and clothianidin.

    Zabar, Romina; Komel, Tilen; Fabjan, Jure; Kralj, Mojca Bavcon; Trebše, Polonca

    2012-09-01

    This research focused on photocatalytic degradation of imidacloprid, thiamethoxam and clothianidin employing a tailor-made photoreactor with six polychromatic fluorescent UVA (broad maximum at 355 nm) lamps and immobilised titanium dioxide (TiO(2)) on glass slides. The disappearance was followed by high pressure liquid chromatography (HPLC-DAD) analyses, wherein the efficiency of mineralization was monitored by measurements of total organic carbon (TOC). Within 2h of photocatalysis, all three neonicotinoids were degraded following first order kinetics with rate constants k=0.035 ± 0.001 min(-1) for imidacloprid, k=0.019 ± 0.001 min(-1) for thiamethoxam and k=0.021 ± 0.000 min(-1) for clothianidin. However, the rate of mineralization was low, i.e. 19.1 ± 0.2% for imidacloprid, 14.4 ± 2.9% for thiamethoxam and 14.1 ± 0.4% for clothianidin. This indicates that several transformation products were formed instead. Some of them were observed within HPLC-DAD analyses and structures were proposed according to the liquid chromatography-electro spray ionization tandem mass spectrometry analyses (LC-ESI-MS/MS). The formation of clothianidin, as thiamethoxam transformation product, was reported for the first time. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Mathematical Modeling of Microwave-Assisted Convective Heating and Drying of Grapes

    This research studied the processing performance and product quality of Thompson seedless grapes dried using microwave-assisted convective hot air drying as well as the effect of blanching and dipping pretreatments. Two pretreatment methods were compared, dipping into 2% ethyl oleate (V/V) and 5% p...

  11. Field emission characteristics of SnO2/CNT composite prepared by microwave assisted wet impregnation

    Kesavan Pillai, Sreejarani

    2012-01-01

    Full Text Available SnO2/CNT composites were prepared by microwave assisted wet impregnation at 60 °C. The process was optimized by varying the microwave power and reaction time. Raman analysis showed the typical features of the rutile phase of as-synthesized SnO2...

  12. DEXTROSE-TEMPLATED MICROWAVE-ASSISTED COMBUSTION SYNTHESIS OF SPONGY METAL OXIDES

    Microwave-assisted combustion synthesis of porous nanocrystalline titania and carbon coated titania is reported using dextrose as template and the product was compared with the one obtained using conventional heating furnace. Out of three compositions viz., 1:1, 1:3, and 1:5 (met...

  13. Microwave-Assisted Synthesis of Mesoporous Nano-Hydroxyapatite Using Surfactant Templates

    Mesoporous nano-hydroxyapatite (n-HAP) was expeditiously synthesized using the pseudo sol-gel microwave-assisted protocol (30 min) in the presence of two novel templates, namely sodium lauryl ether sulfate (SLES) and linear alkylbenzenesulfonate (LABS). The cooperative self-assem...

  14. Pd(OAc)2/DPPF-catalysed microwave-assisted cyanides-free ...

    Pd(OAc)2/DPPF-catalysed microwave-assisted cyanides-free synthesis of aryl nitriles. DINESH N. SAWANT and BHALCHANDRA M. BHANAGE*. Department of Chemistry, Institute of Chemical Technology, N. Parekh Marg, Matunga,. Mumbai 400019 India. e-mail bm.bhanage@ictmumbai.edu.in. INDEX ...

  15. Efficient microwave-assisted synthesis of 5-hydroxymethylfurfural from concentrated aqueous fructose

    Søndergaard Hansen, Thomas; Woodley, John; Riisager, Anders

    2009-01-01

    Studies on the HCl-catalysed microwave-assisted dehydration of highly concentrated aqueous fructose (27 wt %) to 5-hydroxymethylfurfural (HMF) revealed a significant increase in the fructose conversion rate over the conventional heated systems. Water, being the most benign solvent and therefore...

  16. Microwave-assisted solid-phase Ugi four-component condensations

    Nielsen, John

    1999-01-01

    An 18-member library was constructed from 2 isocyanides, 3 aldehydes and 3 carboxylic acids via microwave-assisted solid-phase Ugi reactions on TentaGel S RAM. Products of high purity were obtained in moderate to excellent yields after reaction times of 5 minutes or less (irradiation at 60W). (C...

  17. Microwave-assisted shingled magnetic recording simulations on an exchange-coupled composite medium

    Tanaka, T., E-mail: t-tanaka@ed.kyushu-u.ac.jp [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan); Kashiwagi, S. [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan); Kanai, Y. [Department of Information and Electronics Engineering, Niigata Institute of Technology, Fujihashi 1719, Kashiwazaki, Niigata 945-1195 (Japan); Matsuyama, K. [Department of Electronics, Graduate School of Information Science and Electrical Engineering, Kyushu University, Motoota 744, Nishi-ku, Fukuoka 819-0395 (Japan)

    2016-10-15

    The potential of microwave-assisted magnetic recording combined with the shingled recording scheme has been studied by simulating read/write processes on exchange-coupled composite media focusing on recording characteristics in the cross-track direction. Microwave fields enhance writability, especially at the track edge, resulting in lower noise and higher signal-to-noise ratio (SNR), which enables higher track density in the shingled recording scheme. Read/write simulations of microwave-assisted shingled recording achieve 1.4 Mtracks/in. while retaining high SNR. Further increases in SNR and track density will require either a narrower reader or track edge noise reduction. - Highlights: • Signal recording of shingled magnetic recording using an asymmetric single pole type head combined with a microwave assistance was numerically demonstrated. • Writability is improved by microwave fields with a moderate frequency at the track edge of the shielded side, resulting in higher signal-to-noise ratio. • 1.41 Mtpi of track density is feasible for the recording scheme of shingled magnetic recording with microwave assistance.

  18. Microwave-assisted cationic ring-opening polymerization of a soy-based 2-oxazoline monomer

    Hoogenboom, R.; Wiesbrock, F.D.; Schubert, U.S.

    2005-01-01

    The microwave-assisted cationic ring-opening polymn. of a soy based 2-oxazoline monomer (SoyOx) is described. The microwave irradn. provides more efficient heating when compared to conventional heating and, in addn., the SoyOx was prepd. starting from a sustainable resource (soy beans). The

  19. Rapid and convenient semi-automated microwave-assisted solid-phase synthesis of arylopeptoids

    Rasmussen, Jakob Ewald; Boccia, Marcello Massimo; Nielsen, John

    2014-01-01

    A facile and expedient route to the synthesis of arylopeptoid oligomers (N-alkylated aminomethyl benz-amides) using semi-automated microwave-assisted solid-phase synthesis is presented. The synthesis was optimized for the incorporation of side chains derived from sterically hindered or unreactive...

  20. Scale-up of microwave assisted flow synthesis by transient processing through monomode cavities in series

    Patil, N.G.; Benaskar, F.; Rebrov, E.; Meuldijk, J.; Hulshof, L.A.; Hessel, V.; Schouten, J.C.

    2014-01-01

    A new scale-up concept for microwave assisted flow processing is presented where modular scale-up is achieved by implementing microwave cavities in series. The scale-up concept is demonstrated for case studies of a packed-bed reactor and a wall-coated tubular reactor. With known kinetics and

  1. Microwave assisted air drying of osmotically treated pineapple with variable power programmes

    Botha, GE

    2012-01-01

    Full Text Available Variable power programmes for microwave assisted air drying of pineapple were studied. The pineapple pieces were pre-treated by osmotic dehydration in a 55º Brix sucrose solution at 40ºC for 90 minutes. Variable power output programmes were designed...

  2. Microwave-assisted maleation of tung oil for bio-based products

    In this work, a simple, “green” and convenient chemical modification of tung oil for maleinized tung oil (TOMA) was developed via microwave-assisted one-step maleation. This modifying process did not involve any solvent, catalyst, or initiator, but demonstrated the most efficiency of functionalizing...

  3. Efficient and 'green' microwave-assisted synthesis of haloalkylphosphonates via the Michaelis-Arbuzov reaction

    Jansa, Petr; Holý, Antonín; Dračínský, Martin; Baszczyňski, Ondřej; Česnek, Michal; Janeba, Zlatko

    2011-01-01

    Roč. 13, č. 4 (2011), s. 882-888 ISSN 1463-9262 R&D Projects: GA AV ČR KJB400550903; GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : microwave-assisted synthesis * haloalkylphosphonates * Michaelis-Arbuzov reaction Subject RIV: CC - Organic Chemistry Impact factor: 6.320, year: 2011

  4. Influence of solvent type on microwave-assisted liquefaction of bamboo

    Jiulong Xie; Chung Hse; Todd F. Shupe; Tingxing Hu

    2016-01-01

    Microwave-assisted liquefaction of bamboo in glycerol, polyethylene glycerol (PEG), methanol, ethanol, and water were comparatively investigated by evaluating the temperature-dependence for conversion and liquefied residue characteristics. The conversion for the liquefaction in methanol, ethanol, and water increased with an increase in reaction temperature, while that...

  5. Microwave-assisted shingled magnetic recording simulations on an exchange-coupled composite medium

    Tanaka, T.; Kashiwagi, S.; Kanai, Y.; Matsuyama, K.

    2016-01-01

    The potential of microwave-assisted magnetic recording combined with the shingled recording scheme has been studied by simulating read/write processes on exchange-coupled composite media focusing on recording characteristics in the cross-track direction. Microwave fields enhance writability, especially at the track edge, resulting in lower noise and higher signal-to-noise ratio (SNR), which enables higher track density in the shingled recording scheme. Read/write simulations of microwave-assisted shingled recording achieve 1.4 Mtracks/in. while retaining high SNR. Further increases in SNR and track density will require either a narrower reader or track edge noise reduction. - Highlights: • Signal recording of shingled magnetic recording using an asymmetric single pole type head combined with a microwave assistance was numerically demonstrated. • Writability is improved by microwave fields with a moderate frequency at the track edge of the shielded side, resulting in higher signal-to-noise ratio. • 1.41 Mtpi of track density is feasible for the recording scheme of shingled magnetic recording with microwave assistance.

  6. A detailed study on Sn4+ doped ZnO for enhanced photocatalytic degradation

    Beura, Rosalin; Pachaiappan, R.; Thangadurai, P.

    2018-03-01

    The samples of Sn4+ doped (1, 5, 10, 15, 20 & 30%) ZnO nanostructures were synthesized by a low temperature hydrothermal method. Structural analysis by XRD and Raman spectroscopy showed the hexagonal wurtzite phase of ZnO and the formation of a secondary phase Zn2SnO4 beyond 10% doping of Sn4+. Microstructural analysis by TEM also confirmed the wurtzite ZnO with rod as well as particle like structure. Presence of various functional groups (sbnd OH, sbnd CH, Znsbnd O) were confirmed by FTIR. Optical properties were studied by UV-vis absorption, photoluminescence emission spectroscopies and lifetime measurement. Band gap of the undoped and Sn4+ doped ZnO were analyzed by Tauc plot and it was observed that the band gap of the materials had slightly decreased from 3.2 to 3.16 eV and again increased to 3.23 eV with respect to the increase in the doping concentration from 1 to 30%. A significant change was also noticed in the photoluminescence emission properties of ZnO i.e. increase in the intensity of NBE emission and decrease in DLE, on subject to Sn4+ doping. Average PL lifetime had increased from 29.45 ns for ZnO to 30.62 ns upon 1% Sn ion doping in ZnO. Electrical properties studied by solid state impedance spectroscopy showed that the conductivity had increased by one order of magnitude (from 7.48×10-8 to 2.21×10-7 S/cm) on Sn4+ doping. Photocatalytic experiments were performed on methyl orange (MO) as a model industrial dye under UV light irradiation for different irradiation times. The optimum Sn4+ content in order to achieve highest photocatalytic activity was found to be 1% Sn 4+ doping. The enhancement was achieved due to a decrease in the band gap favoring the generation of electron-hole pairs and the enhanced PL life time that delays the recombination of these charge carrier formation. The third reason was that the increased electrical conductivity that indicated the faster charge transfer in this material to enhance the photocatalytic activity. The Sn

  7. Preparation of Diatomite Supported Nano Zinc Oxide Composite Photocatalytic Material and Study on its Formaldehyde Degradation

    Xiao, Liguang; Pang, Bo

    2017-09-01

    This experiment used zinc nitrate as precursor, ethanol as solvent and polyethylene glycol as dispersant, diatomite as carrier, diatomite loaded nano Zinc Oxide was prepared by sol-gel method, in addition, the formaldehyde degradation was studied by two kinds of experimental methods: preparation and loading, preparation and post loading, The samples were characterized by SEM, XRD, BET and IR. Experimental results showed that: Diatomite based nano Zinc Oxide had a continuous adsorption and degradation of formaldehyde, formaldehyde gas with initial concentration was 0.7mg/m3, after 36h degradation, the concentration reached 0.238mg/m3, the degradation rate reached to 66%.

  8. Sol-Gel-Assisted Microwave-Derived Synthesis of Anatase Ag/TiO2/GO Nanohybrids toward Efficient Visible Light Phenol Degradation

    E. H. Alsharaeh

    2017-05-01

    Full Text Available Abstract: A simple microwave-assisted (MWI wet chemical route to synthesize pure anatase phase titanium dioxide (TiO2 nanoparticles (NPs is reported here using titanium tetrachloride (TiCl4 as starting material. The as-prepared TiO2 NPs were characterized by electron microscopy, X-ray diffraction, UV/visible absorption spectroscopy, and infrared and Raman spectroscopic techniques. Further modification of the anatase TiO2 NPs was carried out by incorporating plasmonic silver (Ag NPs and graphene oxide (GO in order to enhance the visible light absorption. The photocatalytic activities of the anatase TiO2, Ag/TiO2, and Ag/TiO2/GO nanocomposites were evaluated under both ultraviolet (UV and visible light irradiation using phenol as a model contaminant. The presence of Ag NPs was found to play a significant role to define the photocatalytic activity of the Ag/TiO2/GO nanocomposite. It was found that the Ag performed like a sink under UV excitation and stored photo-generated electrons from TiO2, whereas, under visible light excitation, the Ag acted as a photosensitizer enhancing the photocatalytic activity of the nanocomposite. The detailed mechanism was studied based on photocatalytic activities of Ag/TiO2/GO nanocomposites. Therefore, the as-prepared Ag/TiO2/GO nanocomposite was used as photocatalytic materials under both UV and visible light irradiation toward degradation of organic molecules.

  9. Ti O{sub 2}-Based Solar Photocatalytic Degradation of Selected pesticides in aqueous solutions

    Bernecker, A.; Baune, M.; Malato, S.; Thiemann, W.

    1999-07-01

    The photocatalytic oxidation of the pesticides pirimicarb and imidacloprid, using Ti O{sub 2} suspensions under solar radiation, has been studied at pilot-plant scale at the Plataforma Solar de Almeria. The effect of the added Ti O{sub 2}-concentration (ranging from 0 to 1000 mg.dm''-3) and the pH value of the solution (pH values 3, 7 and 10) on the decomposition rates of pirimicarb and imidacloprid oxidation was examined. Addition of Ti O{sub 2} leads to an increase in the reaction rates of both investigated pollutants. A pH dependence is also obvious, but not similar for both pesticides. (Author) 10 refs.

  10. Photocatalytic Degradation of Methyl Orange over Metalloporphyrins Supported on TiO2 Degussa P25

    Xing-Jiao Huang

    2012-01-01

    Full Text Available The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu adsorbed on TiO2 (Degussa P25 surface has been investigated by carrying out the photodegradation of methyl orange (MO under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, diffuse reflectance UV (DRS-UV-vis and infrared spectra. Copper porphyrin-sensitized TiO2 photocatalyst (CuP-TiO2 showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO2 catalyst due to the increase of induced interactions.

  11. Graphene/TiO{sub 2}/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    Hu, Xin-Yan; Zhou, Kefu [College of the Environment and Ecology, Xiamen University, Xiamen (China); Chen, Bor-Yann, E-mail: boryannchen@yahoo.com.tw [Department of Chemical and Materials Engineering, National I-Lan University, Ilan, Taiwan (China); Chang, Chang-Tang, E-mail: ctchang73222@gmail.com [Department of Environmental Engineering, National I-Lan University, Ilan, Taiwan (China)

    2016-01-30

    Graphical abstract: The mechanism of OTC degradation can be described as follows. At first, the OTC molecule was adsorbed onto the surface of GTZ material. The conduction band electron (e{sup −}) and valence band holes (h{sup +}) are generated when aqueous GTZ suspension is irradiated with visible light. The generation of (e{sup −}/h+) pair leading to the formation of reactive oxygen species. The ·OH radical and ·O{sub 2}{sup −} can oxidize OTC molecular, resulting in the degradation and mineralization of the organics. - Highlights: • Determine optimal composites of graphene, TiO{sub 2}, and zeolite for maximal photodegradation efficiency via triangular mixture design. • Unravel most promising composites for high stability and absorptive capabilities for photocatalytic degradation. • Disclose time-series profiles of toxicity of advanced oxidation processes (AOPs) treatment of wastewater. • Propose plausible routes of mechanism of photocatalytical degradation of OTC. - Abstract: This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO{sub 2} loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO{sub 2}), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV–vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min

  12. Graphene/TiO_2/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    Hu, Xin-Yan; Zhou, Kefu; Chen, Bor-Yann; Chang, Chang-Tang

    2016-01-01

    Graphical abstract: The mechanism of OTC degradation can be described as follows. At first, the OTC molecule was adsorbed onto the surface of GTZ material. The conduction band electron (e"−) and valence band holes (h"+) are generated when aqueous GTZ suspension is irradiated with visible light. The generation of (e"−/h+) pair leading to the formation of reactive oxygen species. The ·OH radical and ·O_2"− can oxidize OTC molecular, resulting in the degradation and mineralization of the organics. - Highlights: • Determine optimal composites of graphene, TiO_2, and zeolite for maximal photodegradation efficiency via triangular mixture design. • Unravel most promising composites for high stability and absorptive capabilities for photocatalytic degradation. • Disclose time-series profiles of toxicity of advanced oxidation processes (AOPs) treatment of wastewater. • Propose plausible routes of mechanism of photocatalytical degradation of OTC. - Abstract: This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO_2 loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO_2), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV–vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min photocatalytic treatment, OTC solution treated

  13. Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

    Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

    2013-01-01

    Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

  14. Photocatalytic degradation of 4-amino-6-chlorobenzene-1,3-disulfonamide stable hydrolysis product of hydrochlorothiazide: Detection of intermediates and their toxicity.

    Armaković, Sanja J; Armaković, Stevan; Četojević-Simin, Dragana D; Šibul, Filip; Abramović, Biljana F

    2018-02-01

    In this work we have investigated in details the process of degradation of the 4-amino-6-chlorobenzene-1,3-disulfonamide (ABSA), stable hydrolysis product of frequently used pharmaceutical hydrochlorothiazide (HCTZ), as one of the most ubiquitous contaminants in the sewage water. The study encompassed investigation of degradation by hydrolysis, photolysis, and photocatalysis employing commercially available TiO 2 Degussa P25 catalyst. The process of direct photolysis and photocatalytic degradation were investigated under different type of lights. Detailed insights into the reactive properties of HCTZ and ABSA have been obtained by density functional theory calculations and molecular dynamics simulations. Specifically, preference of HCTZ towards hydrolysis was confirmed experimentally and explained using computational study. Results obtained in this study indicate very limited efficiency of hydrolytic and photolytic degradation in the case of ABSA, while photocatalytic degradation demonstrated great potential. Namely, after 240 min of photocatalytic degradation, 65% of ABSA was mineralizated in water/TiO 2 suspension under SSI, while the nitrogen was predominantly present as NH 4 + . Reaction intermediates were studied and a number of them were detected using LC-ESI-MS/MS. This study also involves toxicity assessment of HCTZ, ABSA, and their mixtures formed during the degradation processes towards mammalian cell lines (rat hepatoma, H-4-II-E, human colon adenocarcinoma, HT-29, and human fetal lung, MRC-5). Toxicity assessments showed that intermediates formed during the process of photocatalysis exerted only mild cell growth effects in selected cell lines, while direct photolysis did not affect cell growth. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Photocatalytic degradation of Acephate, Omethoate, and Methyl parathion by Fe_3O_4@SiO_2@mTiO_2 nanomicrospheres

    Zheng, Lingling; Pi, Fuwei; Wang, Yifan; Xu, Hui; Zhang, Yinzhi; Sun, Xiulan

    2016-01-01

    Highlights: • An efficient photocatalyst Fe_3O_4@SiO_2@mTiO_2 with high magnetic response and large specific surface area was synthesized. • Photocatalytic efficiency of Fe_3O_4@SiO_2@mTiO_2 on Acephate, Omethoate, and Methyl Parathion was higher than TiO_2 P-25. • Possible photocatalytic degradation mechanisms for the Acephate, Omethoate, and Methyl Parathion were proposed. - Abstract: A novel magnetic mesoporous nanomicrospheres Fe_3O_4@SiO_2@mTiO_2 were synthetized and characterized by a series of techniques including FE-TEM, EDS, FE-SEM, PXRD, XPS, BET, TGA as well as VSM, and subsequently tested as a photocatalyst for the degradation of Acephate, Omethoate, and Methyl parathion under UV irradiation. The well-designed nanomicrospheres exhibit a pure and highly crystalline anatase TiO_2 layer, large specific surface area, and high-magnetic-response. Photocatalytic degradation of the three organophosphorus pesticides (OPPs) and the formation intermediates were identified using HPLC, TOC-V_c_p_n, IC, pH meter and GC–MS. Acephate, Omethoate, and Methyl parathion disappeared after 45 min, 45 min, and 80 min UV illumination, respectively. At the end of the treatment, the total organic carbon (TOC) of the OPPs was reduced 80–85%. The main mineralization products were SO_4"2"−, NO_3"− and PO_4"3"− and Omethoate additionally formed NO_2"−. Based on the results, we proposed the photocatalytic degradation pathways for Acephate, Omethoate, and Methyl parathion.

  16. Synthesis, characterization and photocatalytic activity of ZnO flower and pseudo-sphere: Nonylphenol ethoxylate degradation under UV and solar irradiation

    Ashar, Ambreen [Department of Chemistry, University of Agriculture, Faisalabad 38040 (Pakistan); Iqbal, Munawar, E-mail: bosalvee@yahoo.com [Department of Chemistry, Qurtuba University of Science and Information Technology, Peshawar 25100, KPK (Pakistan); Bhatti, Ijaz Ahmad; Ahmad, Muhammad Zubair; Qureshi, Khizar [Department of Chemistry, University of Agriculture, Faisalabad 38040 (Pakistan); Nisar, Jan [National Centre of Excellence in Physical Chemistry, University of Peshawar, Peshawar 25120 (Pakistan); Bukhari, Iftikhar Hussain [Department of Chemistry, Government College University, Faisalabad (Pakistan)

    2016-09-05

    ZnO particles (flower and pseudo sphere) were synthesized via precipitation route and characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Fourier transform infra-red (FTIR) spectroscopy, Atomic force microscopy (AFM), Particle size analyzer and UV–visible techniques. The photocatalytic activities (PCA) of ZnO flower (uncalcined) and pseudo-sphere (calcined) were evaluated by degrading nonylphenol ethoxylate-9 (NP9EO) under UV and solar irradiation. The process variables i.e., catalyst dose, calcination temperature, H{sub 2}O{sub 2} concentration, pH and UV/solar light exposure were investigated and under optimum conditions of process variables, paper, textile and leather industries effluents were also treated. Calcination at high temperature affected the morphology of ZnO particles. Both ZnO flower and pseudo-sphere degraded NP9EO and pollutants in industrial wastewater efficiently under both UV and solar irradiation. Maximum NP9EO degradation was achieved at 2.5 g/L catalyst dose, high calcination temperature, 4% H{sub 2}O{sub 2} concentration, 6 pH, 110 UV exposure and 12 h solar light exposure. Results reveal that ZnO is efficient photo-catalyst and could be used under solar irradiation for photocatalytic application by tuning the band gap. - Highlights: • ZnO flower and pseudo-spheres were synthesized via precipitation route. • The photocatalytic activities by degrading surfactant. • ZnO particles showed considerable photocatalytic activity under UV and solar irradiation. • By tuning the band gap of ZnO absorption capacity can be enhanced.

  17. Rapid and efficient visible light photocatalytic dye degradation using AFe{sub 2}O{sub 4} (A = Ba, Ca and Sr) complex oxides

    Vijayaraghavan, T. [PSG Institute of Advanced Studies, Coimbatore 641004 (India); Suriyaraj, S.P.; Selvakumar, R. [Nanobiotechnology Laboratory, PSG Institute of Advanced Studies, Coimbatore 641004 (India); Venkateswaran, R. [PSG Institute of Advanced Studies, Coimbatore 641004 (India); Ashok, Anuradha, E-mail: anu@psgias.ac.in [PSG Institute of Advanced Studies, Coimbatore 641004 (India)

    2016-08-15

    Highlights: • Alkaline earth ferrites AFe{sub 2}O{sub 4} (A = Ba, Ca and Sr) were synthesized by sol–gel method. • Visible light photocatalytic activity of these ferrites were studied using congo red dye degradation. • BaFe{sub 2}O{sub 4} exhibited the best photocatalytic activity under visible light (xenon lamp) irradiation; CaFe{sub 2}O{sub 4} was the best photocatalyst under natural sun light irradiation. - Abstract: Photocatalytic activity of spinel type complex oxides has been investigated in this study. Alkaline earth ferrites AFe{sub 2}O{sub 4} (A = Ba, Ca, Sr) were synthesized by sol–gel method. Structural characterizations reveal that the synthesized ferrites have orthorhombic crystal structures with different space groups and cell dimensions when they have different alkaline earth metals in their A site. All the synthesized ferrites exhibited their bandgap in the range 2.14–2.19 eV. Their photocatalytic activities were studied using congo red dye under sunlight and xenon lamp radiation. The substitution of Ba, Ca and Sr at A site of these ferrites had varying impact on dye degradation process. Under xenon lamp irradiation, BaFe{sub 2}O{sub 4} exhibited the highest percentage of dye degradation (92% after 75 min). However, CaFe{sub 2}O{sub 4} showed the fastest degradation of the dye (70% within 15 min). In the absence of irradiation, SrFe{sub 2}O{sub 4} showed the highest dye adsorption (44% after 75 min).

  18. The photocatalytic degradation of methylene blue by green semiconductor films that is induced by irradiation by a light-emitting diode and visible light.

    Yang, Chih-Chi; Doong, Ruey-An; Chen, Ku-Fan; Chen, Giin-Shan; Tsai, Yung-Pin

    2018-01-01

    This study develops a low-energy rotating photocatalytic contactor (LE-RPC) that has Cu-doped TiO 2 films coated on stainless-steel rotating disks, to experimentally evaluate the efficiency of the degradation and decolorization of methylene blue (MB) under irradiation from different light sources (visible 430 nm, light-emitting diode [LED] 460 nm, and LED 525 nm). The production of hydroxyl radicals is also examined. The experimental results show that the photocatalytic activity of TiO 2 that is doped with Cu 2+ is induced by illumination with visible light and an LED. More than 90% of methylene blue at a 10 mg/L concentration is degraded after illumination by visible light (430 nm) for 4 hr at 20 rpm. This study also demonstrates that the quantity of hydroxyl radicals produced is directly proportional to the light energy intensity. The greater the light energy intensity, the greater is the number of hydroxyl radicals produced. The CuO-doped anatase TiO 2 powder was successfully synthesized in this study by a sol-gel method. The catalytic abilities of the stainless-steel film were enhanced in the visible light regions. This study has successfully modified the nano-photocatalytic materials to drop band gap and has also successfully fixed the nano-photocatalytic materials on a substratum to effectively treat dye wastewater in the range of visible light. The results can be useful to the development of a low-energy rotating photocatalytic contactor for decontamination purposes.

  19. Ag loaded WO_3 nanoplates for efficient photocatalytic degradation of sulfanilamide and their bactericidal effect under visible light irradiation

    Zhu, Wenyu; Liu, Jincheng; Yu, Shuyan; Zhou, Yan; Yan, Xiaoli

    2016-01-01

    Highlights: • WO_3/Ag heterogeneous composites were fabricated with simply photo-reduction method. • Property changes due to Ag loading were systematically studied. • WO_3/Ag composites efficiently degraded sulfanilamide under visible light irradiation. • WO_3/Ag composites exhibited bactericidal effectS under visible light irradiation. - Abstract: Sulfonamides (SAs) are extensively used antibiotics and their residues in the water bodies propose potential threat to the public. In this study, degradation efficiency of sulfanilamide (SAM), which is the precursor of SAs, using WO_3 nanoplates and their Ag heterogeneous as photocatalysts was investigated. WO_3 nanoplates with uniform size were synthesized by a facile one step hydrothermal method. Different amount of Ag nanoparticles (Ag NPs) were loaded onto WO_3 nanoplates using a photo-reduction method to generate WO_3/Ag composites. The physio-chemical properties of synthesized nanomaterials were systematically characterized. Photodegradation of SAM by WO_3 and WO_3/Ag composites was conducted under visible light irradiation. The results show that WO_3/Ag composites performed much better than pure WO_3 where the highest removal rate was 96.2% in 5 h. Ag as excellent antibacterial agent also endows certain antibacterial efficiency to WO_3, and 100% removal efficiency against Escherichia Coli and Bacillus subtilis could be achieved in 2 h under visible light irradiation for all three WO_3/Ag composites synthesized. The improved performance in terms of SAM degradation and antibacterial activity of WO_3/Ag can be attributed to the improved electron-hole pair separation rate where Ag NPs act as effective electron trapper during the photocatalytic process.

  20. Highly-efficient photocatalytic degradation of methylene blue by PoPD-modified TiO 2 nanocomposites due to photosensitization-synergetic effect of TiO2 with PoPD.

    Yang, Chuanxi; Dong, Wenping; Cui, Guanwei; Zhao, Yingqiang; Shi, Xifeng; Xia, Xinyuan; Tang, Bo; Wang, Weiliang

    2017-06-21

    Poly-o-phenylenediamine modified TiO 2 nanocomposites were successfully synthesized via an 'in situ' oxidative polymerization method. The modified nanocomposites were characterized by BET, XRD, TEM, FT-IR, TGA, XPS, EA and UV-Vis DRS. The photocatalytic degradation of methylene blue was chosen as a model reaction to evaluate the photocatalytic activities of TiO 2 and PoPD/TiO 2 . The results indicated that PoPD/TiO 2 nanocomposites exhibited good photocatalytic activity and stability. The photocatalytic activity of PoPD/TiO 2 increased as the initial pH increased because of electrostatic adsorption between the photocatalyst and MB as well as the generation of ·OH, whereas it exhibited an earlier increasing and later decreasing trend as the concentration of the photocatalyst increased owing to the absorption of visible light. The photocatalytic stability of the PoPD/TiO 2 nanocomposite was dependent on the stability of its structure. Based on radical trapping experiments and ESR measurements, the origin of oxidizing ability of PoPD/TiO 2 nanocomposites on photocatalytic degradation of MB was proposed, which taking into account of ·OH and ·O 2 - were the first and second important ROS, respectively. The possible photocatalytic mechanism and photocatalytic activity enhanced mechanism has been proposed, taking into account the photosensitization effect and synergetic effect of TiO 2 with PoPD.

  1. Bioinspired Synthesis of Photocatalytic Nanocomposite Membranes Based on Synergy of Au-TiO2 and Polydopamine for Degradation of Tetracycline under Visible Light.

    Wang, Chen; Wu, Yilin; Lu, Jian; Zhao, Juan; Cui, Jiuyun; Wu, Xiuling; Yan, Yongsheng; Huo, Pengwei

    2017-07-19

    A bioinspired photocatalytic nanocomposite membrane was successfully prepared via polydopamine (pDA)-coated poly(vinylidene fluoride) (PVDF) membrane, as a secondary platform for vacuum-filtrated Au-TiO 2 nanocomposites, with enhanced photocatalytic activity. The degradation efficiency of Au-TiO 2 /pDA/PVDF membranes reached 92% when exposed to visible light for 120 min, and the degradation efficiency of Au-TiO 2 /pDA/PVDF membranes increased by 26% compared to that of Au-TiO 2 powder and increased by 51% compared to that of TiO 2 /pDA/PVDF nanocomposite membranes. The degradation efficiency remained about 90% after five cycle experiments, and the Au-TiO 2 /pDA/PVDF nanocomposite membranes showed good stability, regeneration performance, and easy recycling. The pDA coating not only served as a bioadhesion interface to improve the bonding force between the catalyst and the membrane substrate but also acted as a photosensitizer to broaden the wavelength response range of TiO 2 , and the structure of Au-TiO 2 /pDA/PVDF also improves the transfer rate of photogenerated electrons; the surface plasmon resonance effect of Au also played a positive role in improving the activity of the catalyst. Therefore, we believe that this study opens up a new strategy in preparing the bioinspired photocatalytic nanocomposite membrane for potential wastewater purification, catalysis, and as a membrane separation field.

  2. Graphene/TiO2/ZSM-5 composites synthesized by mixture design were used for photocatalytic degradation of oxytetracycline under visible light: Mechanism and biotoxicity

    Hu, Xin-Yan; Zhou, Kefu; Chen, Bor-Yann; Chang, Chang-Tang

    2016-01-01

    This first-attempt study revealed mixture design of experiments to obtain the most promising composites of TiO2 loaded on zeolite and graphene for maximal photocatalytic degradation of oxytetracycline (OTC). The optimal weight ratio of graphene, titanium dioxide (TiO2), and zeolite was 1:8:1 determined via experimental design of simplex lattice mixture. The composite material was characterized by XRD, UV-vis, TEM and EDS analysis. The findings showed the composite material had a higher stability and a stronger absorption of the visible light. In addition, it was uniformly dispersed with promising adsorption characteristics. OTC was used as model toxicant to evaluate the photodegradation efficiency of the GTZ (1:8:1). At optimal operating conditions (i.e., pH 7 and 25 °C), complete degradation (ca. 100%) was achieved in 180 min. The biotoxicity of the degraded intermediates of OTC on cell growth of Escherichia coli DH5α were also assayed. After 180 min photocatalytic treatment, OTC solution treated by GTZ (1:8:1) showed insignificant biotoxicity to receptor DH5α cells. Furthermore, EDTA (hole scavengers) and t-BuOH (radical scavengers) were used to detect the main active oxidative species in the system. The results showed that the holes are the main oxidation species in the photocatalytic process.

  3. Enhancement of photocatalytic degradation of polyethylene plastic with CuPc modified TiO2 photocatalyst under solar light irradiation

    Zhao Xu; Li Zongwei; Chen Yi; Shi Liyi; Zhu Yongfa

    2008-01-01

    Solid-phase photocatalytic degradation of polyethylene (PE) plastic, one of the most common commercial plastic, over copper phthalocyanine (CuPc) modified TiO 2 (TiO 2 /CuPc) photocatalyst was investigated in the ambient air under solar light irradiation. Higher PE weight loss rate, greater texture change; more amount of generated CO 2 , which is the main product of the photocatalytic degradation of the composite PEC plastic can be achieved in the system of PE-(TiO 2 /CuPc) in comparison with PE-TiO 2 system. The CuPc promoted charge separation of TiO 2 and enhanced the photocatalytic degradation of PE based on the analysis of surface photovoltage spectroscopy (SPS). During the photodegradation of PE plastic, the reactive oxygen species generated on TiO 2 or TiO 2 /CuPc particle surfaces play important roles. The present study demonstrates that the combination of polymer plastic with TiO 2 /CuPc composite photocatalyst in the form of thin film is a practical and useful way to photodegrade plastic contaminants under solar light irradiation

  4. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  5. Preparation of TiO₂/Carbon Nanotubes/Reduced Graphene Oxide Composites with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B.

    Huang, Yanzhen; Chen, Dongping; Hu, Xinling; Qian, Yingjiang; Li, Dongxu

    2018-06-13

    In this report, ternary titanium dioxide (TiO₂)/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composites were fabricated by a facile and environmentally friendly one-pot solvethermal method for the removal of Rhodamine B (RhB). Its structures were represented by X-ray powder diffraction (XRD), Raman spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic performance was tested by the degradation efficiency of RhB under UV-vis light irradiation. The experimental results indicated that photocatalytic activity improved as the ratio of CNTs:TiO₂ ranged from 0.5% to 3% but reduced when the content increased to 5% and 10%, and the TiO₂/CNTs/rGO-3% composites showed superior photocatalytic activity compared with the binary ones (i.e., TiO₂/CNTs, TiO₂/rGO) and pristine TiO₂. The rate constant k of the pseudo first-order reaction was about 1.5 times that of TiO₂. The improved photocatalytic activity can be attributed to the addition of rGO and CNTs, which reduced the recombination of photo-induced electron-hole pairs, and the fact that CNTs and rGO, with a high specific surface area and high adsorption ability to efficiently adsorb O₂, H₂O and organics, can increase the hydroxyl content of the photocatalyst surface.

  6. Sol-gel synthesis of TiO2 nanoparticles and photocatalytic degradation of methyl orange in aqueous TiO2 suspensions

    Yang Huaming; Zhang Ke; Shi Rongrong; Li Xianwei; Dong Xiaodan; Yu Yongmei

    2006-01-01

    Anatase TiO 2 nanoparticles of about 16 nm in crystal size have been successfully synthesized via a sol-gel method. Thermal treatment of the precursor at 500-600 deg. C results in the formation of different TiO 2 phase compositions. The samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Effects of the pH value of the solution, H 2 O 2 addition, TiO 2 phase composition and recycled TiO 2 on the photocatalytic degradation of methyl orange (MeO) in TiO 2 suspensions under ultraviolet (UV) illumination were primarily investigated. The results indicate that a low pH value, proper amount of H 2 O 2 and pure anatase TiO 2 will facilitate the photocatalytic oxidation of the MeO solution. The photodegradation degree decreases with increasing the pH value of the solution and varies with different amounts of H 2 O 2 . Pure anatase TiO 2 shows better photocatalytic activity for MeO decolorization than biphase TiO 2 . The photocatalytic mechanism of the as-synthesized TiO 2 nanoparticles was discussed

  7. Arrays of Au-TiO{sub 2} Janus-like nanoparticles fabricated by block copolymer templates and their photocatalytic activity in the degradation of methylene blue

    Fu Xiaoning; Liu Jun; Yang Hui; Sun Jiuchuan [Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, School of Chemistry and Chemical Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Li Xue, E-mail: lixue0312@yahoo.com [Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, School of Chemistry and Chemical Engineering, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Zhang Xiaokai [College of Physics and Electronics, Shandong Normal University, 88 Wenhuadong Road, Jinan 250014 (China); Jia Yuxi, E-mail: jia_yuxi@sdu.edu.cn [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

    2011-10-17

    Highlights: {center_dot} Fabrication of an array of Au-titania Janus nanoparticles on silicon substrate. {center_dot} PS-b-PEO block copolymer is used as templates. {center_dot} Au-TiO{sub 2} Janus-like nanoparticles exhibit higher photocatalytic activity. - Abstract: A simple approach towards the fabrication of an array of Au-titania Janus-like nanoparticles is presented. Monolayer organic-inorganic hybrid films are produced by spin coating the mixture of polystyrene-block-poly (ethylene oxide) (PS-b-PEO)/HAuCl{sub 4} solution and titania sol-gel precursor solution. HAuCl{sub 4} and titania are incorporated in the PEO domains. After removing the organic matrix by deep UV irradiation, arrays of Au-TiO{sub 2} Janus-like nanoparticles on the substrate surface are obtained. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements are employed to characterize the Janus-like nanoparticles. The photocatalytic degradation of methylene blue (MB) chosen as the test reaction to examine the photocatalytic activity of the Au-TiO{sub 2} Janus-like nanoparticles is shown to be more effective as compared to that of TiO{sub 2} nanoparticles or Au-TiO{sub 2} composite nanoparticles. The increased photocatalytic activity of Au-TiO{sub 2} Janus-like nanoparticles is attributed to the Au-TiO{sub 2} heterointerfaces.

  8. Enhanced solid-phase photocatalytic degradation of polyethylene by TiO{sub 2}–MWCNTs nanocomposites

    An, Yang [School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Xinjiang 832003 (China); Hou, Juan [College of Sciences, Shihezi University, Xinjiang 832003 (China); Liu, Zhiyong [School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Xinjiang 832003 (China); Peng, Banghua, E-mail: banghuapeng@hotmail.com [School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Xinjiang 832003 (China)

    2014-11-14

    In this work, a novel acid vapor method was introduced to prepare the water soluble multi-walled carbon nanotubes (MWCNTs) and the titanium dioxide (TiO{sub 2})–MWCNTs nanocomposites photocatalyst were successfully synthesized by sol–gel solvothermal method. Products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), which revealed that the anatase TiO{sub 2} particles were uniform deposited on MWCNTs surface. UV–vis diffuse reflectance spectroscopy (UV–vis) showed that composite photocatalyst had an obviously absorption band which covered the whole range of UV–vis region and exhibited a significant enhancement of optical absorption property. Based on above properties, we used the TiO{sub 2}–MWCNTs composites as photocatalysts to degrade the polyethylene (PE) plastic. Solid-phase PE film photocatalytic degradation experiments were investigated through monitoring TiO{sub 2}–MWCNTs–PE composite film's weight loss under mercury lamp irradiation. Results showed that the degradation efficiency could be tuned by changing the concentration of MWCNTs in photocatalyst. The photo-induced degradation of composite film was significantly higher than that of the pure PE film and the Degussa P25-PE film under the same UV irradiation. The weight loss of TiO{sub 2}–MWCNTs (20 wt%)–PE sample reached 35% under 180 h UV-light irradiation. Our work could be extended to synthesize other MWCNTs based composite with the purpose of enhancing TiO{sub 2}'s activity and inspiring for the practical environmental pollution, especially for degradation of plastics. - Highlights: • A novel acid vapor method was used to functionalize the MWCNTs. • Anatase nano-particles of TiO{sub 2} were uniform deposited on MWCNTs surface. • The composite photo-catalyst’s visible-light absorption capability was improved. • Polyethylene film's photodegradation efficiency was obviously enhanced

  9. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation

    Jallouli, Nabil; Elghniji, Kais; Trabelsi, Hassen; Ksibi, Mohamed

    2014-01-01

    In the present study, photocatalytic degradation of acetaminophen ((N-(4-hydroxyphe-nyl)acetamide)), an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegradation of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10−4 M paracetamol was degraded under UV irradiation. Changes in pH values affected the adsorption and the photodegradation of paracetam...

  10. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2

    Triantis, T.M.; Fotiou, T.; Kaloudis, T.; Kontos, A.G.; Falaras, P.; Dionysiou, D.D.; Pelaez, M.; Hiskia, A.

    2012-01-01

    Highlights: ► N-TiO 2 exhibited effective degradation of MC-LR under UV-A, solar and visible light. ► Complete photocatalytic mineralization of MC-LR was achieved under UV-A and solar light. ► The organic nitrogen is mainly released as ammonium and nitrate ions. - Abstract: In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO 2 (N-TiO 2 ) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO 2 , Kronos and reference TiO 2 nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO 2 followed by N-TiO 2 with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO 2 nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO 2 for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO 2 displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO 2 − , NO 3 − and NH 4 + ) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.

  11. Hydrothermal synthesis of fluorinated anatase TiO{sub 2}/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A

    Luo, Lijun [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China); Key Laboratory of Resource Clean Conversion in Ethnic Regions, Education Department of Yunnan, School of Chemistry and Biotechnology, Yunnan MinZu University, Kunming, 650500 (China); Yang, Ye [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China); Zhang, Ali [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Wang, Min; Liu, Yongjun; Bian, Longchun [Advanced Analysis and Measurement Center, Yunnan University, Kunming, 650091 (China); Jiang, Fengzhi, E-mail: fengzhij@ynu.edu.cn [Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091 (China); Pan, Xuejun [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650093 (China)

    2015-10-30

    Graphical abstract: - Highlights: • F–TiO{sub 2}–RGO nanocomposites were synthesized via hydrothermal method. • Presence of F ion prevents phase transformation from anatase to rutile. • The adsorbed F{sup −} and RGO improve the photocatalytic activity of TiO{sub 2} synergistically. • The F–TiO{sub 2}–RGO nanocomposites were applied to degrade bisphenol A. - Abstract: The surface fluorinated TiO{sub 2}/reduced graphene oxide nanocomposites (denoted as F–TiO{sub 2}–RGO) were synthesized via hydrothermal method. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The results showed that pure anatase TiO{sub 2} particles were anchored on the surface of reduced graphene oxide. And the HF added during the preparation process can not only prevent phase transformation from anatase to rutile, but also the F{sup −} ion adsorbed on the surface of TiO{sub 2}–RGO surface can enhance photocatalytic activity of F–TiO{sub 2}–RGO. The photocatalytic activities of F–TiO{sub 2}–RGO nanocomposites were evaluated by decomposing bisphenol A under UV light illumination. Under optimal degradation condition, the degradation rate constant of BPA over F–TiO{sub 2}–10RGO (0.01501 min{sup −1}) was 3.41 times than that over P25 (0.00440 min{sup −1}). The result indicated that the enhanced photocatalytic activity of F–TiO{sub 2}–10RGO was ascribed to the adsorbed F ion and RGO in F–TiO{sub 2}–RGO composite, which can reduce the recombination rate of the photo-generated electrons and holes synergistically.

  12. Solar photocatalytic activity of TiO{sub 2} modified with WO{sub 3} on the degradation of an organophosphorus pesticide

    Ramos-Delgado, N.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Gracia-Pinilla, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas, Av. Universidad, Cd. Universitaria, San Nicolás de los Garza, N.L. (Mexico); Universidad Autónoma de Nuevo León, Centro de Investigación e Innovación en Desarrollo de Ingeniería y Tecnología, PIIT Km 6, Carretera al Aeropuerto, Apodaca, N.L. (Mexico); Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Hernández-Ramírez, A., E-mail: aracely.hernandezrm@uanl.edu.mx [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico)

    2013-12-15

    Highlights: • TiO{sub 2} and WO{sub 3}/TiO{sub 2} (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO{sub 2}. • The mineralization rate was improved when WO{sub 3} content on TiO{sub 2} was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO{sub 3}/TiO{sub 2} photocatalysts synthesized by the sol–gel method with two different percentages of WO{sub 3} (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO{sub 2} was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA{sub BET}), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO{sub 3} was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO{sub 3}/TiO{sub 2} and 1.35 ± 0.3 nm for 5% WO{sub 3}/TiO{sub 2}) and uniformly dispersed on the surface of TiO{sub 2}. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO{sub 3}/TiO{sub 2}, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO{sub 3}/TiO{sub 2} photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO{sub 3}/TiO{sub 2} and bare TiO{sub 2} photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO{sub 3}/TiO{sub 2} catalyst activity on

  13. Facile Synthesis of Nickel Chromite Nanostructures by Hydrothermal Route for Photocatalytic Degradation of Acid Black 1 under Visible Light

    F. Beshkar

    2015-01-01

    Full Text Available NiCr2O4 normal spinel nanostructures were prepared via hydrothermal treatment at 180 °C for 12 h in the presence of cetyltrimethylammonium bromide (CTAB, sodium dodecyl sulphate (SDS and poly vinylpyrrolidone-25000 (PVP-25000 as capping agents and subsequent calcination process at 500 °C for 3 h . In this method, [Ni(en2(H2O2](NO32 and [Cr(en3]Cl3.3H2O used as precursors and not utilized any alkaline or precipitating agent. Detailed characterization of  the as-prepared nanostructures were carried out by Fourier transform infrared (FTIR, X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, UV-Vis diffuse reflectance spectroscopy (DRS. XRD revealed the formation of pure nickel chromite spinel phase and SEM showed the formation of uniform sphere-like nanoparticles. Furthermore, the photocatalytic degradation of acid black 1 as diazo dye used in textile and dyeing water pollutants was Investigated.

  14. Photocatalytic degradation of some organic dyes under solar light irradiation using TiO2 and ZnO nanoparticles

    Mojtaba Amini

    2016-01-01

    Full Text Available Nanoparticles of the ZnO and TiO2 were synthesized and the physicochemical properties of the compounds were characterized by IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD patterns of the ZnO and TiO2 nanoparticles could be indexed to hexagonal and rutile phase, respectively. Aggregated nanoparticles of ZnO and TiO2 with spherical-like shapes were observed with particle diameter in the range of 80-100 nm. These nanoparticles were used for photocatalytic degradation of various dyes, Rhodamine B (RhB, Methylene blue (MB and Acridine orange (AO under solar light irradiation at room temperature. Effect of the amount of catalyst on the rate of photodegradation was investigated. In general, because ZnO is unstable, due to incongruous dissolution to yield Zn(OH2 on the ZnO particle surfaces and thus leading to catalyst inactivation,the catalytic activity of the system for photodegradation of dyes decreased dramatically when TiO2 was replaced by ZnO.

  15. Sunlight assisted photocatalytic degradation of Indigo Carmine using eco-friendly synthesized CdSnO3

    Ashok V. Borhade

    2016-03-01

    Full Text Available In the present study I have developed an eco-friendly mechanochemical solid state method with green chemistry approach for the synthesis of CdSnO3. The photocatalyst was characterized to carry out physicochemical characterization by various analytical techniques like, Fourier Transform Infrared (FT-IR, Ultraviolet diffused reflectance Spectroscopy (UV-DRS, X-ray Diffraction (XRD, Scanning Electron Microscopy (SEM, Tunnelling Electron Microscopy (TEM and Brunauer–Emmett– Teller (BET surface area. The synthesized CdSnO3 particles had an average size of 105 nm with band gap 3.17 eV. The surface area by BET isotherm method highlight for the synthesized photocatalyst (SBET is 54.45 m2/g, with pore volume (Vp is 0.021 cc/g, and pore diameter (Dp is 24.85 Aº. Photocatalytic activity of CdSnO3 was demonstrated by degradation of Indigo carmine dye under influence of sunlight in aqueous solution

  16. Preparation of nano-TiO2/diatomite-based porous ceramics and their photocatalytic kinetics for formaldehyde degradation

    Gao, Ru-qin; Sun, Qian; Fang, Zhi; Li, Guo-ting; Jia, Meng-zhe; Hou, Xin-mei

    2018-01-01

    Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650°C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm-1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated under UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were κ = 0.576 mg·m-3·min-1 and K = 0.048 m3/mg.

  17. Photocatalytic degradation kinetics and mechanism of environmental pharmaceuticals in aqueous suspension of TiO{sub 2}: A case of {beta}-blockers

    Yang Hai [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Kehua Street, Tianhe District, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); An Taicheng, E-mail: antc99@gig.ac.cn [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Kehua Street, Tianhe District, Guangzhou 510640 (China); Li Guiying [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Kehua Street, Tianhe District, Guangzhou 510640 (China); Song Weihua; Cooper, William J. [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175 (United States); Luo Haiying [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Kehua Street, Tianhe District, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Guangzhou Product Quality Supervision and Testing Institute, National Centre for Quality Supervision and Testing of Processed Food (Guangzhou), Guangzhou 510110 (China); Guo Xindong [Guangzhou Product Quality Supervision and Testing Institute, National Centre for Quality Supervision and Testing of Processed Food (Guangzhou), Guangzhou 510110 (China)

    2010-07-15

    This study investigated the photocatalytic degradation of three {beta}-blockers in TiO{sub 2} suspensions. The disappearance of the compounds followed pseudo-first-order kinetics according to the Langmuir-Hinshelwood model and the rate constants were 0.075, 0.072 and 0.182 min{sup -1} for atenolol, metoprolol and propranolol, respectively. After 240 min irradiation, the reaction intermediates were completely mineralized to CO{sub 2} and the nitrogen was predominantly as NH{sub 4}{sup +}. The influence of initial pH and {beta}-blocker concentration on the kinetics was also studied. From adsorption studies it appears that the photocatalytic degradation occurred mainly on the surface of TiO{sub 2}. Further studies indicated that surface reaction with {center_dot}OH radical was principally responsible for the degradation of these three {beta}-blockers. The major degradation intermediates were identified by HPLC/MS analysis. Cleavage of the side chain and the addition of the hydroxyl group to the parent compounds were found to be the two main degradation pathways for all three {beta}-blockers.

  18. Attapulgite-CeO{sub 2}/MoS{sub 2} ternary nanocomposite for photocatalytic oxidative desulfurization

    Li, Xiazhang, E-mail: lixiazhang509@163.com [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States); Zhang, Zuosong [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Yao, Chao [Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164 (China); Lu, Xiaowang [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Zhao, Xiaobing [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory for Environment Functional Materials, Suzhou University of Science and Technology, Suzhou 215009 (China); Ni, Chaoying [W.M.Keck Center for Advanced Microscopy and Microanalysis, University of Delaware, Newark, DE 19716 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were fabricated. • ATP possessed outstanding adsorption property and enhanced the stability of the network structure. • CeO{sub 2}/MoS{sub 2} couples facilitated the separation of photo-induced electrons and holes. • Mass ratio of CeO{sub 2}/MoS{sub 2} influenced the photocatalytic oxidation desulfurization. - Abstract: Novel attapulgite(ATP)-CeO{sub 2}/MoS{sub 2} ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV–vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO{sub 2}/MoS{sub 2} composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO{sub 2} to MoS{sub 2} on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO{sub 2} particles and MoS{sub 2} nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO{sub 2}/MoS{sub 2} is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.

  19. One-pot engineering TiO2/graphene interface for enhanced adsorption and photocatalytic degradation of multiple organics.

    Song, Jianhua; Ling, Yun; Xie, Yu; Liu, Lianjun; Zhu, Huihua

    2018-06-13

    It is challenging to design a multifunctional structure or composite for simultaneously adsorb and photocatalytic degrade organic pollutants in water. Towards this goal, this work innovatively engineered interfacial sites between TiO2 particles and reduced graphene oxide (RGO) sheets by employing in situ one-pot one-step solvothermal method. The interface was associated with the content of RGO, solvothermal time and solvent ratio of n-pentanol to n-hexane. It was found that when at a moderate amount of RGO (25%), TiO2 nanoparticles were well dispersed on the surface of RGO or wrapped by RGO, thus leading to a fully contact and strong interaction to form Ti - O - C interfacial structure. But when at a low content of RGO (6%), TiO2 aggregates were mixture of nanosheets, nanoparticles and nanorods. 25%RGO/TiO2 also had 175% higher surface area (146m2/g), 95% larger volume (0.339 cm3/g) and smaller band gap than 6%RGO/TiO2. More importantly, 25%RGO/TiO2 demonstrated higher adsorption efficiency (25%) and 4 times faster degradation rate than TiO2 (0%). It also exhibited good capability to eliminate multiple organics and stable long-term cycle performance (up to 93% retention after 30 cycles). Its superiority was attributed to the large surface area and unique interface between TiO2 and RGO, which not only provided more active sites to capture pollutants but also enhanced charge transfer (3 µA/cm2, 5 times higher than TiO2). This work offered a promising way to purify water through engineering new materials structure and integrating adsorption and photodegradation technologies. © 2018 IOP Publishing Ltd.

  20. Mn2O3 decorated graphene nanosheet: An advanced material for the photocatalytic degradation of organic dyes

    Chandra, Sourov; Das, Pradip; Bag, Sourav; Bhar, Radhaballabh; Pramanik, Panchanan

    2012-01-01

    Graphical abstract: A facile and economical route has been developed for the synthesis of graphene–Mn 2 O 3 nanocomposite in which Mn 2 O 3 nanoparticles are uniformly distributed throughout the surface of the graphene nanosheet with their average sizes ranging from 8 to 10 nm. It shows a brilliant catalytic activity during the photodegradation of several organic dyes as compare to both of the bare manganese oxide and graphene too. Highlights: ► One step sonochemical synthesis of graphene–Mn 2 O 3 nanocomposite. ► Growth of such nanoparticles over graphene is accelerated by the simultaneous reduction with KMnO 4 . ► The composite can effectively use as heterogeneous catalyst during the photodegradation of organic dyes. ► It exhibits ∼84%, ∼80% and ∼60% degradation of MB, eosin and RB respectively within a few minutes. - Abstract: A one step sonochemical route has been developed to prepare graphene–Mn 2 O 3 nanocomposite with uniform distribution of Mn 2 O 3 nanoparticles throughout the surface of graphene nanosheet. Growth of such nanoparticles over this two dimensional carbon network is simply accelerated by the simultaneous reduction of potassium permanganate along with graphene oxide, in which metal ions are first anchored through binding with oxy-functional groups of graphene oxide and finally reduced by hydrazine. The final product ensure a new platform for the photodegradation of organic dyes, as it can store electrons and circulate them towards dye molecules through the formation of hydroxyl radical under the exposure of UV-light. Almost 80% photocatalytic degradation of eosin, methylene blue and rhodamine B have been observed within few minutes, which has not been obtained by using bare manganese oxide itself.

  1. TUNGSTOPHOSPHORIC ACID HETEROGENIZED ONTO NH4ZSM5 AS AN EFFICIENT AND RECYCLABLE CATALYST FOR THE PHOTOCATALYTIC DEGRADATION OF DYES

    Candelaria Leal Marchena

    2015-05-01

    Full Text Available Materials based on tungstophosphoric acid (TPA immobilized on NH4ZSM5 zeolite were prepared by wet impregnation of the zeolite matrix with TPA aqueous solutions. Their concentration was varied in order to obtain TPA contents of 5%, 10%, 20%, and 30% w/w in the solid. The materials were characterized by N2 adsorption-desorption isotherms, XRD, FT-IR, 31P MAS-NMR, TGA-DSC, DRS-UV-Vis, and the acidic behavior was studied by potentiometric titration with n-butylamine. The BET surface area (SBET decreased when the TPA content was raised as a result of zeolite pore blocking. The X-ray diffraction patterns of the solids modified with TPA only presented the characteristic peaks of NH4ZSM5 zeolites, and an additional set of peaks assigned to the presence of (NH43PW12O40. According to the Fourier transform infrared and 31P magic angle spinning-nuclear magnetic resonance spectra, the main species present in the samples was the [PW12O40]3- anion, which was partially transformed into the [P2W21O71]6- anion during the synthesis and drying steps. The thermal stability of the NH4ZSM5TPA materials was similar to that of their parent zeolites. Moreover, the samples with the highest TPA content exhibited band gap energy values similar to those reported for TiO2. The immobilization of TPA on NH4ZSM5 zeolite allowed the obtention of catalysts with high photocatalytic activity in the degradation of methyl orange dye (MO in water, at 25 ºC. These can be reused at least three times without any significant decrease in degree of degradation.

  2. Hydrothermal synthesis of Bismuth(III) coordination polymer and its transformation to nano α-Bi{sub 2}O{sub 3} for photocatalytic degradation

    Huang, Ya-Jing; Zheng, Yue-Qing, E-mail: zhengnbu@163.com; Zhu, Hong-Lin; Wang, Jin-Jian

    2016-07-15

    A new Bi(III) coordination polymer Bi{sub 2}(Hpdc){sub 2}(pdc){sub 2}·2H{sub 2}O (H{sub 2}pdc=pyridine-2,6-dicarboxylic acid) was synthesized by hydrothermal method. Solid state thermal decomposition of this complex under 500 °C for 1 h led to the foliated Bi{sub 2}O{sub 3} nanoparticles, which were then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Comparative study on their photocatalytic activity toward the degradation of rhodamine B (RhB), methylene blue (MB) and methyl orange (MO) in polluted water was explored, and the mechanism of these photocatalytic degradation was discussed. These results provided some interesting insights into their photocatalytic applications. - Graphical abstract: We regard Bi{sub 2}(Hpdc){sub 2}(pdc){sub 2}·2H{sub 2}O with 1D chain structures as the precursor, then calcinate the complex to prepare nano-powder α-Bi{sub 2}O{sub 3}. The photochemical experiment indicates that Bi{sub 2}(Hpdc){sub 2}(pdc){sub 2}·2H{sub 2}O can be used as an efficient photocatalyst for the degradation of RhB and MB. Interestingly, nano α-Bi{sub 2}O{sub 3} shows higher activity than the commercial Bi{sub 2}O{sub 3} for the degradation of RhB, MB or MO. Display Omitted - Highlights: • A novel dinuclear Bi(III) coordination polymer is hydrothermally synthesized. • Calcinating the precursor Bi-CP will result in the nano Bi{sub 2}O{sub 3} with foliated morphology. • Nano Bi{sub 2}O{sub 3} shows higher activity than the commercial Bi{sub 2}O{sub 3} for the degradation of dyes.

  3. Enhancing ethylbenzene vapors degradation in a hybrid system based on photocatalytic oxidation UV/TiO2–In and a biofiltration process

    Hinojosa-Reyes, M.; Rodríguez-González, V.; Arriaga, S.

    2012-01-01

    Highlights: ► The best photocatalytic system for EB degradation was based on TiO 2 –In 1%/365 nm. ► A maximum EC of 290 g m −3 h −1 for the hybrid system was obtained. ► The hybrid process enhanced 40% the overall EC of ethylbenzene. ► An overall mineralization of 67% for EB degradation was reached in the hybrid system. - Abstract: The use of hybrid processes for the continuous degradation of ethylbenzene (EB) vapors has been evaluated. The hybrid system consists of an UV/TiO 2 –In photooxidation coupled with a biofiltration process. Both the photocatalytic system using P25-Degussa or indium-doped TiO 2 catalysts and the photolytic process were performed at UV-wavelengths of 254 nm and 365 nm. The experiments were carried out in an annular plug flow photoreactor packed with granular perlite previously impregnated with the catalysts, and in a glass biofilter packed with perlite and inoculated with a microbial consortium. Both reactors were operated at an inlet loading rate of 127 g m −3 h −1 . The greatest degradation rate of EB (0.414 ng m −2 min −1 ) was obtained with the TiO 2 –In 1%/365 nm photocatalytic system. The elimination capacity (EC) obtained in the control biofilter had values ∼60 g m −3 h −1 . Consequently, the coupled system was operated for 15 days, and a maximal EC of 275 g m −3 h −1 . Thus, the results indicate that the use of hybrid processes enhanced the EB vapor degradation and that this could be a promising technology for the abatement of recalcitrant volatile organic compounds.

  4. Enhancing ethylbenzene vapors degradation in a hybrid system based on photocatalytic oxidation UV/TiO{sub 2}-In and a biofiltration process

    Hinojosa-Reyes, M. [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Ciencias Ambientales, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico); Rodriguez-Gonzalez, V. [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Materiales Avanzados, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico); Arriaga, S., E-mail: sonia@ipicyt.edu.mx [Instituto Potosino de Investigacion Cientifica y Tecnologica A.C., Division de Ciencias Ambientales, Camino a la Presa San Jose 2055, Lomas 4a seccion, CP. 78216, San Luis Potosi, S.L.P. (Mexico)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer The best photocatalytic system for EB degradation was based on TiO{sub 2}-In 1%/365 nm. Black-Right-Pointing-Pointer A maximum EC of 290 g m{sup -3} h{sup -1} for the hybrid system was obtained. Black-Right-Pointing-Pointer The hybrid process enhanced 40% the overall EC of ethylbenzene. Black-Right-Pointing-Pointer An overall mineralization of 67% for EB degradation was reached in the hybrid system. - Abstract: The use of hybrid processes for the continuous degradation of ethylbenzene (EB) vapors has been evaluated. The hybrid system consists of an UV/TiO{sub 2}-In photooxidation coupled with a biofiltration process. Both the photocatalytic system using P25-Degussa or indium-doped TiO{sub 2} catalysts and the photolytic process were performed at UV-wavelengths of 254 nm and 365 nm. The experiments were carried out in an annular plug flow photoreactor packed with granular perlite previously impregnated with the catalysts, and in a glass biofilter packed with perlite and inoculated with a microbial consortium. Both reactors were operated at an inlet loading rate of 127 g m{sup -3} h{sup -1}. The greatest degradation rate of EB (0.414 ng m{sup -2} min{sup -1}) was obtained with the TiO{sub 2}-In 1%/365 nm photocatalytic system. The elimination capacity (EC) obtained in the control biofilter had values {approx}60 g m{sup -3} h{sup -1}. Consequently, the coupled system was operated for 15 days, and a maximal EC of 275 g m{sup -3} h{sup -1}. Thus, the results indicate that the use of hybrid processes enhanced the EB vapor degradation and that this could be a promising technology for the abatement of recalcitrant volatile organic compounds.

  5. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  6. Hydrothermal synthesis of CdS nanoparticle/functionalized graphene sheet nanocomposites for visible-light photocatalytic degradation of methyl orange

    Yan, Shancheng; Wang, Bojun; Shi, Yi; Yang, Fan; Hu, Dong; Xu, Xin; Wu, Jiansheng

    2013-01-01

    CdS nanoparticle/functionalized graphene sheet (CdS NP/FGS) nanocomposites were successfully prepared in a one-step hydrothermal synthesis route. The samples were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy. In addition, the photocatalytic performance of CdS NP/FGS composites and pure CdS in the degradation of methyl orange (MO) was examined using visible light. Results show that the addition of FGS can enhance the photocatalytic performance of CdS NP/FGS composites with a maximum degradation efficiency of 98.1% under visible light irradiation as compared with pure CdS (60.1%). This finding can be attributed to three reasons. First is the strong redox ability of CdS in the nanocomposite with smaller crystal size. Second is the increase in specific surface area for more adsorbed MO. Third is the reduction in electron–hole pair recombination with the introduction of FGS. Based on their high photocatalytic activity, the CdS NP/FGS composites can be expected to be a practical visible light photocatalyst.

  7. Physicochemcial characteristic of CdS-anchored porous WS2 hybrid in the photocatalytic degradation of crystal violet under UV and visible light irradiation

    Vattikuti, S. V. Prabhakar; Ngo, Ich-Long; Byon, Chan

    2016-11-01

    In this work, we report the synthesis of CdS-incorporated porous WS2 by a simple hydrothermal method. The structural, morphological, and optical properties of the samples were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), high resolution X-ray photoelectron spectroscopy (XPS) and UV-visible spectrometry. The photocatalytic activities were established for degradation of crystal violet (CV) under UV and visible light irradiation. The CdS-incorporated porous WS2 hybrid demonstrated high photocatalytic activity for degradation of CV pollutant compared to pure CdS nanoparticles and porous WS2 sheets. This result implies that the CdS-incorporated porous WS2 promoted more electron-hole pair transformation under UV and visible light irradiation. This significant enhancement of photocatalytic efficiency of CdS-incorporated porous WS2 photocatalyst under visible light can be ascribed to the presence of CdS nanospheres on the meshed-like WS2 sheets which potentially improves absorption in the visible range enabled by surface plasmon resonance effect of CdS nanospheres. The photostability and reusability of the CdS-porous WS2 were examined through recycling experiments.

  8. SILAR BiOI-Sensitized TiO2 Films for Visible-Light Photocatalytic Degradation of Rhodamine B and 4-Chlorophenol.

    Odling, Gylen; Robertson, Neil

    2017-04-05

    BiOI nanoplates were deposited upon a film of TiO 2 nanoparticles derived from a commercial source using a simple room temperature sequential ionic layer adsorption and reaction (SILAR) method. X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopies have been used to confirm the crystal phase, chemical states of key elements and morphology of the BiOI nanoplate-TiO 2 composites. Using both valence band X-ray photoelectron spectroscopy and UV/Vis diffuse reflectance measurements the band structure of the composites is determined to be that of a type II heterojunction. Through initial screening of the photocatalytic activity of the SILAR-modified films it was determined that five SILAR cycles are optimal in the photocatalytic degradation of rhodamine B. The visible-light sensitisation effect of BiOI was then proven by examination of the photocatalytic degradation of the colourless organic pollutant 4-chlorophenol, showing a large enhancement over an equivalent TiO 2 film. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. (0 0 1) Facet-exposed anatase-phase TiO{sub 2} nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    Zhou, Xun [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Shi, Tiejun, E-mail: stjhfut@163.com [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Wu, Jing [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Zhou, Haiou [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); School of Materials and Chemical Engineering of Anhui University of Architecture, Hefei 230901 (China)

    2013-12-15

    Reduced graphene oxide (RGO) and TiO{sub 2} nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO{sub 2} powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by C-Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO{sub 2} powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  10. Hydrothermal synthesis of CdS nanoparticle/functionalized graphene sheet nanocomposites for visible-light photocatalytic degradation of methyl orange

    Yan, Shancheng, E-mail: yansc@njupt.edu.cn [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wang, Bojun [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Shi, Yi [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yang, Fan; Hu, Dong; Xu, Xin; Wu, Jiansheng [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China)

    2013-11-15

    CdS nanoparticle/functionalized graphene sheet (CdS NP/FGS) nanocomposites were successfully prepared in a one-step hydrothermal synthesis route. The samples were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy. In addition, the photocatalytic performance of CdS NP/FGS composites and pure CdS in the degradation of methyl orange (MO) was examined using visible light. Results show that the addition of FGS can enhance the photocatalytic performance of CdS NP/FGS composites with a maximum degradation efficiency of 98.1% under visible light irradiation as compared with pure CdS (60.1%). This finding can be attributed to three reasons. First is the strong redox ability of CdS in the nanocomposite with smaller crystal size. Second is the increase in specific surface area for more adsorbed MO. Third is the reduction in electron–hole pair recombination with the introduction of FGS. Based on their high photocatalytic activity, the CdS NP/FGS composites can be expected to be a practical visible light photocatalyst.

  11. Microwave-assisted Facile and Ultrafast Growth of ZnO Nanostructures and Proposition of Alternative Microwave-assisted Methods to Address Growth Stoppage

    Rana, Abu Ul Hassan Sarwar; Kang, Mingi; Kim, Hyun-Seok

    2016-04-01

    The time constraint in the growth of ZnO nanostructures when using a hydrothermal method is of paramount importance in contemporary research, where a long fabrication time rots the very essence of the research on ZnO nanostructures. In this study, we present the facile and ultrafast growth of ZnO nanostructures in a domestic microwave oven within a pressurized environment in just a few minutes. This method is preferred for the conventional solution-based method because of the ultrafast supersaturation of zinc salts and the fabrication of high-quality nanostructures. The study of the effect of seed layer density, growth time, and the solution’s molar concentration on the morphology, alignment, density, and aspect ratio of ZnO nanorods (ZNRs) is explored. It is found in a microwave-assisted direct growth method that ~5 mins is the optimum time beyond which homogeneous nucleation supersedes heterogeneous nucleation, which results in the growth stoppage of ZNRs. To deal with this issue, we propound different methods such as microwave-assisted solution-replacement, preheating, and PEI-based growth methods, where growth stoppage is addressed and ZNRs with a high aspect ratio can be grown. Furthermore, high-quality ZnO nanoflowers and ZnO nanowalls are fabricated via ammonium hydroxide treatment in a very short time.

  12. Comparison of Microwave-Assisted and Hydrodistillation Methods for Extraction of Essential Oil from Achillea millefolium

    S. Mollasalehi

    2013-08-01

    Full Text Available Microwave-assisted hydrodistillation (MAHD method has been compared with hydrodistillation (HD conventional technique for extraction of essential oil from Achillea millefolium. Microwave-assisted hydrodistillation were examined at three levels of microwave powers (300, 500, and 700 W. Obtained results show that MAHD offers important advantages over HD in terms of energy savings and extraction time (20 min against 2.5 h. Also, the essential oils were analyzed by GC-MS. The amount of oxygenated compounds and monoterpene, such as 1,8 -Cineole, Lavandulyl acetate,Caryophylla-dien, Aromadendrene were increased in the microwave method. All these results suggest that MAHD represents an excellent alternative method for extraction of essential oils from plant materials.

  13. Microwave assisted synthesis of luminescent carbonaceous nanoparticles from silk fibroin for bioimaging.

    Gao, Hongzhi; Teng, Choon Peng; Huang, Donghong; Xu, Wanqing; Zheng, Chaohui; Chen, Yisong; Liu, Minghuan; Yang, Da-Peng; Lin, Ming; Li, Zibiao; Ye, Enyi

    2017-11-01

    Bombyx mori silk as a natural protein based biopolymer with high nitrogen content, is abundant and sustainable because of its mass product all over the world per year. In this study, we developed a facile and fast microwave-assisted synthesis of luminescent carbonaceous nanoparticles using Bombyx mori silk fibroin and silk solution as the precursors. As a result, the obtained carbonaceous nanoparticles exhibit a photoluminescence quantum yield of ~20%, high stability, low cytotoxicity, high biocompatibility. Most importantly, we successfully demonstrated bioimaging using these luminescent carbonaceous nanoparticles with excitation dependent luminescence. In addition, the microwave-assisted hydrothermal method can be extended to convert other biomass into functional nanomaterials. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Microwave-assisted extraction of metal elements from glass fibrous filters for aerosol sampling

    Li Dong-Mei; Zhang Li-Xing; Wang Xu-Hui; Liu Long-Bo

    2003-01-01

    Atmospheric aerosols are generally collected on filters according to the International Monitoring System (IMS) designed in the Comprehensive Nuclear-Test-Ban Treaty (CTBT). More information could be revealed when the filter sample is pretreated rather than measured directly by γ-ray spectrometer. Microwave-assisted extraction (MAE) is a suitable method that gives higher recoveries of elements from glass fibrous filters under different conditions. The results indicate that the MAE is a highly efficient and robust method for the treatment of glass fibrous filter samples. The recoveries of potential fission products from glass fibrous filter samples by microwave-assisted extraction meet the efficiency of the extraction by both aqua regia and 2% HCl. (author)

  15. Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method

    Cao, Wenqian [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Chen, Zhi, E-mail: zchen0@gmail.com [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Gao, Tong; Zhou, Dantong; Leng, Xiaonan; Niu, Feng [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Zhu, Yuxiang [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, Tianjin (China); Qin, Laishun, E-mail: qinlaishun@yeah.net [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Wang, Jiangying; Huang, Yuexiang [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China)

    2016-06-01

    This paper describes on the fast synthesis of bismuth ferrite by the simple microwave-assisted hydrothermal method. The phase transformation and the preferred growth facets during the synthetic process have been investigated by X-ray diffraction. Bismuth ferrite can be quickly prepared by microwave hydrothermal method by simply controlling the reaction time, which is further confirmed by Fourier Transform infrared spectroscopy and magnetic measurement. - Graphical abstract: Single-phase BiFeO{sub 3} could be realized at a shortest reaction time of 65 min. The reaction time has strong influences on the phase transformation and the preferred growth facets. - Highlights: • Rapid synthesis (65 min) of BiFeO{sub 3} by microwave-assisted hydrothermal method. • Reaction time has influence on the purity and preferred growth facets. • FTIR and magnetic measurement further confirm the pure phase.

  16. Optimization of microwave-assisted extraction of polysaccharide from Psidium guajava L. fruits.

    Amutha Gnana Arasi, Michael Antony Samy; Gopal Rao, Manchineela; Bagyalakshmi, Janardanan

    2016-10-01

    This study deals with the optimization of microwave assisted extraction of polysaccharide from Psidium guajava L. fruit using Response surface methodology. To evaluate the effect of three independent variables, Water to plant material ratio, microwave power used for extraction and Irradiation time, central composite design has been employed. The yield is considered as dependent variable. The design model estimated the optimum yield of 6.81677% at 200W microwave power level, 3:1 water to plant material ratio and 20min of irradiation time. Three factors three levels Central composite design coupled with RSM was used to model the extraction process. ANOVA was performed to find the significance of the model. The polysaccharide extracted using microwave assisted extraction process was analyzed using FTIR Spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Microwave-assisted extraction of green coffee oil and quantification of diterpenes by HPLC.

    Tsukui, A; Santos Júnior, H M; Oigman, S S; de Souza, R O M A; Bizzo, H R; Rezende, C M

    2014-12-01

    The microwave-assisted extraction (MAE) of 13 different green coffee beans (Coffea arabica L.) was compared to Soxhlet extraction for oil obtention. The full factorial design applied to the microwave-assisted extraction (MAE), related to time and temperature parameters, allowed to develop a powerful fast and smooth methodology (10 min at 45°C) compared to a 4h Soxhlet extraction. The quantification of cafestol and kahweol diterpenes present in the coffee oil was monitored by HPLC/UV and showed satisfactory linearity (R(2)=0.9979), precision (CV 3.7%), recovery (yield calculated on the diterpenes content for sample AT1 (Arabica green coffee) showed a six times higher value compared to the traditional Soxhlet method. Copyright © 2014 Elsevier Ltd. All rights reserved.