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Sample records for oxide-coated composite adsorbent

  1. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid.

    Wang, Lingling; Han, Changseok; Nadagouda, Mallikarjuna N; Dionysiou, Dionysios D

    2016-08-01

    Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2·6H2O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21±1°C was about 60mgCg(-1). The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents. PMID:27135170

  2. Simple and Efficient Synthesis of Iron Oxide-Coated Silica Gel Adsorbents for Arsenic Removal: Adsorption Isotherms and Kinetic Study

    Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite (AsO2-) and arsenate (AsO4-3), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of 10 μg/L without adjusting pH and temperature, which would be highly advantageous for practical field application

  3. Reduced graphene oxide-coated hydroxyapatite composites stimulate spontaneous osteogenic differentiation of human mesenchymal stem cells

    Lee, Jong Ho; Shin, Yong Cheol; Jin, Oh Seong; Kang, Seok Hee; Hwang, Yu-Shik; Park, Jong-Chul; Hong, Suck Won; Han, Dong-Wook

    2015-07-01

    Human mesenchymal stem cells (hMSCs) have great potential as cell sources for bone tissue engineering and regeneration, but the control and induction of their specific differentiation into bone cells remain challenging. Graphene-based nanomaterials are considered attractive candidates for biomedical applications such as scaffolds in tissue engineering, substrates for SC differentiation and components of implantable devices, due to their biocompatible and bioactive properties. Despite the potential biomedical applications of graphene and its derivatives, only limited information is available regarding their osteogenic activity. This study concentrates upon the effects of reduced graphene oxide (rGO)-coated hydroxyapatite (HAp) composites on osteogenic differentiation of hMSCs. The average particle sizes of HAp and rGO were 1270 +/- 476 nm and 438 +/- 180 nm, respectively. When coated on HAp particulates, rGO synergistically enhanced spontaneous osteogenic differentiation of hMSCs, without hampering their proliferation. This result was confirmed by determining alkaline phosphatase activity and mineralization of calcium and phosphate as early and late stage markers of osteogenic differentiation. It is suggested that rGO-coated HAp composites can be effectively utilized as dental and orthopedic bone fillers since these graphene-based particulate materials have potent effects on stimulating the spontaneous differentiation of MSCs and show superior bioactivity and osteoinductive potential.Human mesenchymal stem cells (hMSCs) have great potential as cell sources for bone tissue engineering and regeneration, but the control and induction of their specific differentiation into bone cells remain challenging. Graphene-based nanomaterials are considered attractive candidates for biomedical applications such as scaffolds in tissue engineering, substrates for SC differentiation and components of implantable devices, due to their biocompatible and bioactive properties. Despite

  4. Analysis of the Composition of Titanium Oxide Coating by Laser Induced Breakdown Spectroscopy

    Estupiñán, Hugo; Peña, Dario Y.; Cabanzo, Rafael; Mejía-Ospino, Enrique

    2008-04-01

    Laser Induced Plasma Spectroscopy (LIPS or LIBS) is an alternative elemental analysis technology based on the optical emission spectra of the plasma produced by the interaction of high-power laser with gas, solid and liquid. The increasing popularity of this technique is due to the ease of the experimental set-up and to the wide fiexibility in the investigated material that does not need any pre-treatment of the sample before the analysis. In this work, Laser Induced Breakdown Spectroscopy (LIBS) is used to determine the composition of titanium oxide film produced by anodized of Ti6Al4V alloy. We have used Ti lines in the spectral region between 470-520 nm to determine temperature of the plasma generated on anodized surface of Ti6Al4V alloy for temperature determination by Boltzmann plot method. In order to measure the content of oxygen and titanium ratio on the surface the alloy, we have used the oxygen lines 777.194, 777.417 and 777.539 nm, and titanium lines 780.597 and 782.491 nm observed in an ambient of argon. We have determined the best conditions of electro-deposition, observing the intensity of the oxygen lines. Finally, we report the possibilities for the determination of the coating chemical composition using LIBS.

  5. Arsenic Removal from Water Using Various Adsorbents: Magnetic Ion Exchange Resins, Hydrous Ion Oxide Particles, Granular Ferric Hydroxide, Activated Alumina, Sulfur Modified Iron, and Iron Oxide-Coated Microsand

    Sinha, Shahnawaz

    2011-09-30

    The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four natural types (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxide particles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated mic - rosand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The results showed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determined for a given equilibrium concentration of C eq = 10 μg/L were 500 mg/L for AA and GFH, 520–1,300 mg/L for MIEX, 1,200 mg/L for HIOPs, 2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbents were 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantly reduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenic in the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbents had lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreased by approximately 60–95 % .

  6. The influences of microdischarge types and silicate on the morphologies and phase compositions of plasma electrolytic oxidation coatings on Zircaloy-2

    Highlights: ► ZrO2 coatings are grown on Zircaloy-2 by plasma electrolytic oxidation. ► Characteristic solidification structures are formed on the coatings. ► This structure has not been found on the PEO coatings of other valve metals. ► Very low thermal conductivity of zirconia helps the formation of the structure. - Abstract: Plasma electrolytic oxidation coatings were formed in alkaline silicate electrolyte on Zircaloy-2. The evolution of the types of discharges, the microstructures, phase compositions and the corrosion resistance of the coatings were studied by real time imaging, SEM, XRD, and electrochemical tests. Characteristic solidification structures were revealed in the PEO coatings, the formation of the solidification structures is related to the long lasting discharges during the PEO process and the very low thermal conductivity of zirconium oxide. Thermal effect in the coatings and silicate content in the electrolyte affect the phase compositions of the coatings.

  7. Effect of current density on the structure, composition and corrosion resistance of plasma electrolytic oxidation coatings on Mg–Li alloy

    Highlights: ► The PEO coatings exhibit tunable characteristics by controlling the current density. ► The coating formed at 5 A/dm2 exhibits the highest corrosion resistance. ► Anti-corrosion properties of PEO coatings are related to coating surface composition. - Abstract: The effect of current density on the oxidation process, morphology, composition and anti-corrosion properties of coatings are elucidated. X-ray photoelectron spectroscopy and X-ray diffraction analysis of coatings show that coatings prepared at different current densities are composed of MgO and γ-Mg2SiO4 and α-Mg2SiO4 phase. The chemical composition of PEO coatings varies from surface to the interior of the oxide coating. The PEO coatings exhibit tunable thickness, composition ratio, and porosity by controlling the current density, which ultimately affects film morphology and anti-corrosion properties. The superior corrosion resistance of coating obtained at 5 A/dm2 is attributed to the compactness of the barrier layer and the highest MgO/Mg2SiO4 ratio.

  8. Effect of current density on the structure, composition and corrosion resistance of plasma electrolytic oxidation coatings on Mg-Li alloy

    Li, Zhijun [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yuan, Yi, E-mail: yi.yuan@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Jing, Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The PEO coatings exhibit tunable characteristics by controlling the current density. Black-Right-Pointing-Pointer The coating formed at 5 A/dm{sup 2} exhibits the highest corrosion resistance. Black-Right-Pointing-Pointer Anti-corrosion properties of PEO coatings are related to coating surface composition. - Abstract: The effect of current density on the oxidation process, morphology, composition and anti-corrosion properties of coatings are elucidated. X-ray photoelectron spectroscopy and X-ray diffraction analysis of coatings show that coatings prepared at different current densities are composed of MgO and {gamma}-Mg{sub 2}SiO{sub 4} and {alpha}-Mg{sub 2}SiO{sub 4} phase. The chemical composition of PEO coatings varies from surface to the interior of the oxide coating. The PEO coatings exhibit tunable thickness, composition ratio, and porosity by controlling the current density, which ultimately affects film morphology and anti-corrosion properties. The superior corrosion resistance of coating obtained at 5 A/dm{sup 2} is attributed to the compactness of the barrier layer and the highest MgO/Mg{sub 2}SiO{sub 4} ratio.

  9. Kinetic Study of Lead Adsorption to Composite Biopolymer Adsorbent.

    Seki; Suzuki

    1999-03-15

    A kinetic study of lead adsorption to composite biopolymer adsorbents was carried out. Spherical and membranous adsorbents containing two biopolymers, humic acid and alginic acid, were used for lead adsorption in dilute acidic solutions. The shrinking core model derived by M. G. Rao and A. K. Gupta (Chem. Eng. J. 24, 181, 1982) was applied to describe the rate process of lead adsorption to spherical adsorbents (average radii of 0.12, 0.15, and 0.16 cm). Furthermore, the shrinking core model was modified and adapted for description of the rate process of lead adsorption to membranous adsorbent (average thickness of 0.0216 cm). The adsorption rate process for the both cases was well described and average apparent lead diffusion coefficients of about 6 x 10(-6) and 7 x 10(-6) cm2 s-1 were found for the spherical and membranous adsorbents, respectively. Copyright 1999 Academic Press. PMID:10049553

  10. Influence of Material Composition on Structural and Optical Properties of HfO2-TiO2 Mixed Oxide Coatings

    Michal Mazur

    2016-03-01

    Full Text Available In this paper the influence of material composition on the structural, surface and optical properties of HfO2-TiO2 mixed oxide coatings was investigated and discussed. Five sets of thin films were deposited using reactive magnetron sputtering: HfO2, TiO2 and three sets of mixed HfO2-TiO2 coatings with various titanium content. The change in the material composition had a significant influence on the structural, surface and optical properties. All of the deposited coatings, except for (Hf0.55Ti0.45Ox, were nanocrystalline with crystallites ranging from 6.7 nm to 10.8 nm in size. Scanning electron microscopy measurements revealed that surface of nanocrystalline thin films consisted of grains with different shapes and sizes. Based on optical transmission measurements, it was shown that thin films with higher titanium content were characterized by a higher cut-off wavelength, refractive index and lower optical band gap energy. The porosity and packing density were also determined.

  11. Isothermal composite adsorbent. Part I: Thermal characterisation

    Adsorption and desorption are respectively exo and endothermic phenomena leading to significant temperature changes in adsorption columns. Enhanced efficiency of a sorption process could be obtained under isothermal conditions, either for gas storage, purification or separation applications. The heat transfer within the adsorbent beds can be managed in situ, using thermal energy storage material: a phase change materials (PCM) for example. The thermal behaviour of a mixture of activated carbon and PCM during CO2 adsorption has been studied. The thermal characteristics of the involved materials have been determined and experiments carried out to highlight the positive effect of the PCM to reduce the CO2 adsorption heat effects on an activated carbon bed. Calorimetry was the technique used for all the thermal characterisations. It appears that the heat effects induced by CO2 adsorption are reduced by the presence of the PCM together with the adsorbent. The endothermic effect of fusion balances the heat effect of adsorption and significantly reduces the temperature changes

  12. REVIEW: USE of COMPOSITE ADSORBENTS in ADSORPTION REFRIGERATION

    Satishchandra V. Joshi

    2012-01-01

    Full Text Available The urbanization across the world has resulted in increased demand for refrigeration and air conditioning. The main disadvantage with the conventional method i.e. vapor compression system is environment pollution. Another problem faced during urbanization is energy crisis. The adsorption refrigeration system is one of the solutions to this problem. The advantages of this system are environment friendly, less noise, use of waste heat or solar energy. But the disadvantage with adsorption system is low coefficient of performance (COP and bulkiness. Researchers across the world are working on this issue to make adsorption system a viable alternative to the compression systems. Since the last two decades considerable work is being done on the use of composite adsorbents to improve the heat and mass transfer performance. This kind of adsorbent is usually obtained by the combination of a chemical adsorbents and physical adsorbents.

  13. A note on chemical composition and origin of ferromanganese oxide coated and uncoated pumice samples from central Indian Ocean basin

    Pattan, J.N.; Parthiban, G.; Moraes, C.; Rajalakshmi, R.; Lekshmi, S.; Athira, S.; JaiSankar, S.

    the physical properties of pumice such as density, specific gravity, porosity, void ratio and degree of saturation. Detailed studies related to chemical composition of both coated and uncoated pumice from CIOB are rare (Pattan et al, 2008). The objective..., N. G., IYER, S. D. and ILANGOVAN, D. (2011) Physical properties, morphology and petrological characteristics of pumices from the Central Indian Ocean Basin. Acta Geologica Sinica., v. 85, pp. 826-839. KAY, S. M. (2001) Tertiary to Recent...

  14. Study on the adsorption performance of composite adsorbent of CaCl2 and expanded graphite with ammonia as adsorbate

    A novel constant volume test unit was built to study the adsorption performance of a new type composite adsorbent. This test unit can measure the adsorption isosteres of the working pairs. The adsorption isosteres are the curves of the adsorption pressure variation with the adsorption temperatures at constant adsorption quantities. Compared to the former test results of isothermals and isobars, the isosteres are better for the calculation of the adsorption heat, desorption heat and the selection the adsorption working pairs. Three experimental results were obtained: the first result was that the expanded graphite powders were superior to the expandable graphite powders to facilitate the transportation of working fluid in the composite adsorbent. The second one was that the composite adsorbent treated by solution is more homogeneous than the simple mixed composite adsorbent and the treated composite adsorbent has a better mass transfer performance. The last one was that the adsorption isosteres was the same one not only in the heating process but also in the cooling process and this performance was not relevant to the homogeneity of the composite adsorbent

  15. Characterization and adsorption behavior of a novel triolein-embedded activated carbon composite adsorbent

    RU Jia; LIU Huijuan; QU Jiuhui; WANG Aimin; DAI Ruihua

    2005-01-01

    A novel triolein-embedded activated carbon composite adsorbent was developed. Experiments were carried out in areas such as the preparation method, the characterization of physicochemical properties, and the adsorption behavior of the composite adsorbent in removing dieldrin from aqueous solution. Results suggested that the novel composite adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. The adsorbent was stable in water, for no triolein leakage was detected after soaking the adsorbent for five weeks. The adsorbent had good adsorption capability to dieldrin, which was indicated by a residual dieldrin concentration of 0.204 μg·L-1. The removal efficiency of the composite adsorbent was higher than the traditional activated carbon adsorbent.

  16. Oxide coating development

    Stinton, D.P.

    1995-06-01

    Monolithic SiC heat exchangers and fiber-reinforced SiC-matrix composite heat exchangers and filters are susceptible to corrosion by alkali metals at elevated temperatures. Protective coatings are currently being developed to isolate the SiC materials from the corrodants. Unfortunately, these coatings typically crack and spall when applied to SiC substrates. The purpose of this task is to determine the feasibility of using a compliant material between the protective coating and the substrate. The low-modulus compliant layer could absorb stresses and eliminate cracking and spalling of the protective coatings.

  17. Electrochemical niobium oxide coating in molten NaNO3-KNO3

    Kinetics of anodic oxide film growth on niobium in molten NaNO3-KNO3 (50 mol %) is studied in galvanostatic and potentiostatic conditions. Basic kinetic parameters of the oxide-coating process are determined. Chemical composition of the oxide coatings is established

  18. Design and performance prediction of a new generation adsorption chiller using composite adsorbent

    Research highlights: → Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. → A new type adsorbent bed is used to accommodate the composite adsorbent. → A dynamic model of the adsorption chiller is built. → The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

  19. Effective thermal conductivity of expanded graphite-CaCl2 composite adsorbent for chemical adsorption chillers

    This paper presents experimental data on the thermal conductivity for three types of adsorbent, namely, pure CaCl2 powder, simple composite adsorbent and consolidated composite adsorbent. The thermal conductivities were measured by the 'hot wire method' at a fixed pressure and temperature under an ammonia atmosphere. Effective thermal conductivities of the expanded graphite-CaCl2 . nNH3 (n = 2, 4, 8) consolidated composite adsorbent are in the range of 7.05-9.2 W m-1 K-1, which are significant higher values than those of the powders bed of 0.3-0.4 W m-1 K-1. The obtained results show that the composite adsorbent thermal conductivity λ has a strong dependence on the bulk density, the weight fraction of expanded graphite and the ammoniated state of CaCl2

  20. Removing Cd2+ by Composite Adsorbent Nano-Fe3O4/Bacterial Cellulose

    LU Min; GUAN Xiao-hui; WEI De-zhou

    2011-01-01

    A new composite adsorbent,nano-Fe3O4/bacterial cellulose(BC),was prepared through blending method.The process of adsorbing Cd2+ including its isotherm and kinetics measured was studied.The results show that the adsorption efficiency is improved because of huge surface area and surface coordination of nano-Fe3O4 particles.Its adsorption capacity is 27.97 mg/g and the maximum of Cd2+ removal is 74%.The adsorption kinetics can be described by pseudo-second rate model and the adsorption equilibrium by Langmuir type.The superparamagnetism of nano-Fe3O4 particles can help to solve the difficult separation of single BC adsorbent and lead to the quick separation of composite adsorbent from the liquid if a magnetic field was applied.Cd2+ can be desorbed effectively by EDTA and HCl from the composite adsorbent,which can make it be reused.

  1. Graphene oxide/chitin nanofibril composite foams as column adsorbents for aqueous pollutants.

    Ma, Zhongshi; Liu, Dagang; Zhu, Yi; Li, Zehui; Li, Zhenxuan; Tian, Huafeng; Liu, Haiqing

    2016-06-25

    A novel graphene oxide/chitin nanofibrils (GO-CNF) composite foam as a column adsorbent was prepared for aqueous contaminant disposal. The structures, morphologies and properties of composite foams supported by nanofibrils were characterized. As a special case, the adsorption of methylene blue (MB) on GO-CNF was investigated regarding the static adsorption and column adsorption-desorption tests. Results from equilibrium adsorption isotherms indicated that the adsorption behavior was well-fitted to Langmuir model. The composite foams reinforced by CNF were dimensionally stable during the column adsorption process and could be reused after elution. The removal efficiency of MB was still nearly 90% after 3 cycles. Furthermore, other inorganic or organic pollutants adsorbed by composite foams were also explored. Therefore, this novel composite foam with remarkable properties such as dimensional stability, universal adsorbent for cationic pollutants, high adsorption capacity, and ease of regeneration was a desirable adsorbent in the future practical application of water pollutant treatment. PMID:27083813

  2. The preparation of composite fiber adsorbents for separation of uranium from seawater by spinning(1)

    Amidoximated composite fiber adsorbents were prepared for separation of uranium from seawater and characterized by various instrumental techniques, such as IR spectroscopy, CHN elemental analyzer and SEM. The swelling ratios and yields of the AN-TEGMA and AN-TEGMA-DVB copolymers were decreased with an increase in crosslinking agents, such as DVB and TEGMA composition. The yield of 85-92% and 82-88% of AN-TEGMA and AN-TEGMA-DVB copolymers respectively were found. The porosity was also decreased with increase in crosslinking compositions, and it was found that the AN-TEGMA-DVB porosity copolymers were smaller than the value of AN-TEGMA copolymer. We investigated that the adsorbent with the composite fiber adsorbents were well dispersed on the surface of its by SEM. The optimum contents of containing adsorbent in the copolymer was 40 weight percent. The capacity of uranyl ion through the composite fiber adsorbent containing the amidoxime group was maximized a pH level of 8. Also, it was found that the synthesized composite fiber adsorbent was good material, due to a pH level of 8.3 of seawater, for separation of uranyl ion from seawater. (author)

  3. AMMONIA AND COD REMOVAL FROM SYNTHETIC LEACHATE USING RICE HUSK COMPOSITE ADSORBENT

    Azhar Abdul Halim

    2011-06-01

    Full Text Available Ammonia and chemical oxygen demand (COD were the most two problematic parameters in the landfill leachate. In this study, a new composite adsorbent derived from rice husk ash waste is evaluated with respect to its ability to remove these contaminants from synthetic leachate. Results indicate that the new composite adsorbent is able to adsorb both ammonia and COD. It has a higher adsorption capacity for ammonia (Q = 2.2578 mg/g and an almost equal adsorption capacity for COD (Q = 2.8893 when compared with commercially activated carbon. The adsorption kinetics of this new product for ammonia and COD were primarily represented by the pseudo second-order mechanism. The overall adsorption rate of the ammonia and COD adsorption processes appears to be determined by chemisorption process. The regenerated composite adsorbent indicated higher adsorption capacities of ammonia and COD, i.e. 12.9366 mg/g and 3.1162 mg/g, respectively.

  4. In Vitro Corrosion and Cytocompatibility of a Microarc Oxidation Coating and Poly(l-lactic acid) Composite Coating on Mg-1Li-1Ca Alloy for Orthopedic Implants.

    Zeng, Rong-Chang; Cui, Lan-Yue; Jiang, Ke; Liu, Rui; Zhao, Bao-Dong; Zheng, Yu-Feng

    2016-04-20

    Manipulating the degradation rate of biomedical magnesium alloys poses a challenge. The characteristics of a microarc oxidation (MAO), prepared in phytic acid, and poly(l-lactic acid) (PLLA) composite coating, fabricated on a novel Mg-1Li-1Ca alloy, were studied through field emission scanning electron microscopy (FE-SEM), electron probe X-ray microanalysis (EPMA), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion behaviors of the samples were evaluated via hydrogen evolution, potentiodynamic polarization and electrochemical impedance spectroscopy in Hanks' solution. The results indicated that the MAO/PLLA composite coatings significantly enhanced the corrosion resistance of the Mg-1Li-1Ca alloy. MTT and ALP assays using MC3T3 osteoblasts indicated that the MAO/PLLA coatings greatly improved the cytocompatibility, and the morphology of the cells cultured on different samples exhibited good adhesion. Hemolysis tests showed that the composite coatings endowed the Mg-1Li-1Ca alloys with a low hemolysis ratio. The increased solution pH resulting from the corrosion of magnesium could be tailored by the degradation of PLLA. The degradation mechanism of the composite coatings was discussed. The MAO/PLLA composite coating may be appropriate for applications on degradable Mg-based orthopedic implants. PMID:27022831

  5. Effect of sandblasting intensity on microstructures and properties of pure titanium micro-arc oxidation coatings in an optimized composite technique

    Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; He, Kun; Yuan, Y. F.; Ma, Xiao-Ni; Li, Ying

    2014-02-01

    Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.

  6. Effect of pulse frequency on the microstructure, phase composition and corrosion performance of a phosphate-based plasma electrolytic oxidation coated AM50 magnesium alloy

    An AM50 magnesium alloy was plasma electrolytic oxidation treated using a pulsed DC power supply at three different pulse frequencies viz., 10 Hz, 100 Hz and 1000 Hz with a constant pulse ratio for 15 min in an alkaline phosphate electrolyte. The resultant coatings were characterized by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy for their phase composition and microstructural features. The 10 Hz condition yielded relatively thick and rough coatings, which was attributed to the higher energy input per individual pulse during the PEO processing. The phase composition was also found to be influenced by the processing frequency. Electrochemical impedance spectroscopy studies performed in 0.1 M NaCl solutions revealed that the coatings produced at 10 Hz condition had a better corrosion resistance, which was attributed to the higher thickness, more compact microstructural features and a relatively stable phase composition.

  7. Copper ions removal from water using functionalized carbon nanotubes–mullite composite as adsorbent

    Highlights: • CNTs–mullite composite was prepared via chemical vapor deposition (CVD) method. • The prepared composite was modified with concentrated nitric acid and chitosan. • The modified CNTs–mullite composites were used as novel adsorbents. • Copper ion removal from water by the prepared adsorbents was performed. • Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. - Abstract: Carbon nanotubes–mullite composite was synthesized by direct growth of carbon nanotubes on mullite particles via chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively. The carbon nanotubes–mullite composite was oxidized with concentrated nitric acid and functionalized with chitosan and then used as a novel adsorbent for copper ions removal from water. The results demonstrated that modification with concentrated nitric acid and chitosan improves copper ions adsorption capacity of the prepared composite, significantly. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. The carbon nanotubes growth on mullite particles to form the carbon nanotubes–mullite composite with further modification is an inherently safe approach for many promising environmental applications to avoid some concerns regarding environment, health and safety. It was found that the modified carbon nanotubes–mullite composite can be considered as an excellent adsorbent for copper ions removal from water

  8. Copper ions removal from water using functionalized carbon nanotubes–mullite composite as adsorbent

    Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj, E-mail: torajmohammadi@iust.ac.ir

    2015-08-15

    Highlights: • CNTs–mullite composite was prepared via chemical vapor deposition (CVD) method. • The prepared composite was modified with concentrated nitric acid and chitosan. • The modified CNTs–mullite composites were used as novel adsorbents. • Copper ion removal from water by the prepared adsorbents was performed. • Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. - Abstract: Carbon nanotubes–mullite composite was synthesized by direct growth of carbon nanotubes on mullite particles via chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively. The carbon nanotubes–mullite composite was oxidized with concentrated nitric acid and functionalized with chitosan and then used as a novel adsorbent for copper ions removal from water. The results demonstrated that modification with concentrated nitric acid and chitosan improves copper ions adsorption capacity of the prepared composite, significantly. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. The carbon nanotubes growth on mullite particles to form the carbon nanotubes–mullite composite with further modification is an inherently safe approach for many promising environmental applications to avoid some concerns regarding environment, health and safety. It was found that the modified carbon nanotubes–mullite composite can be considered as an excellent adsorbent for copper ions removal from water.

  9. Bioinspired Polyelectrolyte-Assembled Graphene-Oxide-Coated C18 Composite Solid-Phase Microextraction Fibers for In Vivo Monitoring of Acidic Pharmaceuticals in Fish.

    Qiu, Junlang; Chen, Guosheng; Liu, Shuqin; Zhang, Tianlang; Wu, Jiayi; Wang, Fuxin; Xu, Jianqiao; Liu, Yan; Zhu, Fang; Ouyang, Gangfeng

    2016-06-01

    A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring. PMID:27189112

  10. Sorption of U(VI) on natural sepiolite and sepiolite-agar agar composite adsorbent

    Adsorption of uranium (VI) ions onto clay minerals is one of the significant reactions affecting the transport of uranium in the environment. The use of composite adsorbents for the removal of metal ions and radionuclide from industrial wastes has attracted great interest to researchers in recent years[1]. In this study, natural sepiolite type clay and an organic compound, agar agar, were chosen as the adsorbent material. Composite adsorbent was prepared from sepiolite and agar agar. Adsorption of uranium (VI) on this composite and on natural sepiolite adsorbent was investigated. Thermodynamic investigations were carried out to get more information about the adsorption of uranium. Adsorption of U (VI) has been studied as a function of solution pH, time, temperature and initial concentration of uranium on natural sepiolite and agar agar composite. The maximum sorption yield of U (VI) on composite and on sepiolite from batch experiments is calculated approximately 89% and 76% respectively in the optimum experimental adsorption condition. The adsorption data were fitted to Freundlich and Dubinin-Radushkevich (D-R) adsorption isotherms. Using the experimental data obtained different temperatures, thermodynamic constants ΔHdegree, ΔSdegree and ΔGdegree were calculated. The results show that the adsorption process on natural sepiolite and sepiolite-agar agar composite are both egzothermic natures. [1] S. M. Hasany, M. M. Saeed, M. Ahmed, J. Radioanal. Nucl. Chem. Vol. 252 (3), 477-484 (2002)

  11. In situ toughened SiC ceramics with Al-B-C additions and oxide-coated SiC platelet/SiC composites

    Cao, J. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

    1996-12-01

    This work aimed at fabrication and characterization of high toughness SiC ceramics through the applications of in situ toughening and SiC platelet reinforcement. The processing-microstructure-property relations of hot pressed SiC with Al, B, and C additions (designated as ABC-SiC) were investigated. Through a liquid phase sintering mechanism, dense SiC was obtained by hot pressing at a temperature as low as 1,700 C with 3 wt% Al, 0.6 wt% B, and 2 wt% C additions. These sintering aids also enhanced the {beta}-to-{alpha} (3C-to-4H) phase transformation, which promoted SiC grains to grow into plate-like shapes. Under optimal processing conditions, the microstructure exhibited high-aspect-ratio plate-shaped grains with a thin (< 1 nm) Al-containing amorphous grain boundary film. The mechanical properties of the toughened SiC and the composites were evaluated in comparison with a commercial Hexoloy SiC under identical test conditions. The C-curve behavior was examined using the strength-indentation load relationship and compared with that directly measured using precracked compact tension specimens. The in situ toughened ABC-SiC exhibited much improved flaw tolerance and a significantly rising R-curve behavior. A steady-state toughness in excess of 9 MPam{sup 1/2} was recorded for the ABC-SiC in comparison to a single valued toughness below 3 MPam{sup 1/2} for the Hexoloy. Toughening in the ABC-SiC was mainly attributed to grain bridging and subsequent pullout of the plate-shaped grains. The high toughness ABC-SiC exhibited a bend strength of 650 MPa with a Weibull modulus of 19; in comparison, the commercial SiC showed a bend strength of 400 MPa with a Weibull modulus of 6. Higher fracture toughness was also achieved by the reinforcement of SiC platelets, encapsulated with alumina, yttria, or silica, in a SiC matrix.

  12. Desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent, (1)

    An investigation was carried out on the desorption of uranium from titanium-activated carbon composite adsorbent with acidic eluent by the batch process. The rate of desorption of uranium with acidic eluent depended on temperature, showing an increase as the temperature was raised. But the rate of desorption with acidic eluent was less dependent on temperature than that obtained when mixed eluent of sodium carbonate-sodium hydrogencarbonate was used. The difference of the rate of desorption of uranium in the range of concentration from 0.3 to 0.5N was not found, and the rate of desorption with sulfuric acid was slightly higher than that obtained when hydrochloric acid was used. The amount of dissolved titanium decreased as the ratio of adsorbent to eluent (RAE) was increased. At RAE of 10%, the percentage of dissolved titanium (DTI) was below 0.38% with sulfuric acid, below 0.7% with hydrochloric acid. These values were found to be higher than the ones with the carbonate eluent. The elements except uranium, which were adsorbed on the adsorbent, were eluted simultaneously with acidic eluent. The regeneration of the adsorbent after desorption, therefore, was found to be unnecessary. In a repeated test of adsorption-desorption treatment up to five times, the percentage of uranium adsorbed from natural sea water was approximately constant of 85%. From these results, the application of column process to the desorption of uranium with acidic eluent at room temperature was proposed to be feasible. (author)

  13. Studies on broad spectrum corrosion resistant oxide coatings

    Someswar Datta

    2001-12-01

    The corrosion resistant oxide coatings, developed and applied by the conventional vitreous enamelling techniques, showed superior resistance to a range of mineral acids at various strengths and temperatures, alkaline solutions, boiling water and chrome plating solutions. These coatings possess considerable abrasion and impact resistance as well as high thermal shock resistance. The properties of the coating system have been studied in detail and found to be strongly dependent on composition and processing parameters. These coatings have been characterized by X-ray diffraction analysis and SEM studies. Some of the coating materials have been found to be biocompatible.

  14. ADSORPTION OF Cr(VI FROM AQUEOUS SOLUTION USING CARBON-MICROSILICA COMPOSITE ADSORBENT

    DEYI ZHANG

    2012-03-01

    Full Text Available In this work, Microsilica, one kind of industry solid waste material, was utilized firstly to prepare a carbon-Microsilica composite adsorbent from a partial carbonization, mixture and sulfoxidation process and was proposed for the removal of Cr(VI from solutions. The surface chemistry characteristics of the prepared adsorbent were analysis by XPS and FT-IR. The characterization results indicated that an abundant of oxygen functional groups, such as hydroxyl, carboxyl and sulfonic groups, were introduced into the surface of the prepared composite adsorbent. Meanwhile, the adsorption characteristics of Cr(VI onto the adsorbent in aqueous solutions was studied as a function of solution pH, ionic strength, contact time, and temperature. The results showed that Cr(VI adsorption onto the adsorbent is strongly dependent on pH and, to a lesser extent, ionic strength. Kinetics data were found to follow the pseudo-second-order kinetic model while the adsorption data corresponded to L-shape adsorption isotherm which corresponds to the classification of Giles. Activation thermodynamic parameters, such as activation enthalpy (ΔH*, activation entropy (ΔS*, activation Gibbs free energy (ΔG* and activation energy (E, have been evaluated and the possible adsorption mechanism also was suggested.

  15. Alumina-Activated Carbon Composite as Adsorbent of Procion Red Dye from Wastewater Songket Industry

    Poedji Loekitowati Hariani; Fatma Fatma; Zulfikar Zulfikar

    2015-01-01

    Alumina-activated carbon composite has been synthesized and studied for adsorption procion red dye. Composite was prepared by precipitation method aluminium hydroxide on the surface of activated carbon followed by calcinations. The Fourier transform Infra Red (FTIR), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) and Brunaeur Emmet Teller (BET) surface are being used to characterize the adsorbent. Batch adsorption experiments were carried out for the adsorption of...

  16. Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells

    Graphical abstract: - Highlights: • Ir/Ti-oxide coated surfaces are characterized by the so-called “cracked-mud” morphology. • 40% Ir in the coating material results in a morphologically uniform coating. • ECs and SMCs showed a desirable response to the Ir/Ti-oxide coated surfaces. • Ir/Ti-oxide coated surfaces are more bio/hemocompatible than the untreated 316L stainless steel. - Abstract: Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of IrxTi1−x-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications

  17. Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells

    Habibzadeh, Sajjad [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Li, Ling [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada); Omanovic, Sasha [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Shum-Tim, Dominique [Divisions of Cardiac Surgery and Surgical Research, Department of Surgery, McGill University, Montreal, QC (Canada); Davis, Elaine C., E-mail: elaine.davis@mcgill.ca [Department of Anatomy and Cell Biology, McGill University, Montreal, QC (Canada)

    2014-05-01

    Graphical abstract: - Highlights: • Ir/Ti-oxide coated surfaces are characterized by the so-called “cracked-mud” morphology. • 40% Ir in the coating material results in a morphologically uniform coating. • ECs and SMCs showed a desirable response to the Ir/Ti-oxide coated surfaces. • Ir/Ti-oxide coated surfaces are more bio/hemocompatible than the untreated 316L stainless steel. - Abstract: Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of Ir{sub x}Ti{sub 1−x}-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir{sub 0.2}Ti{sub 0.8}-oxide and Ir{sub 0.4}Ti{sub 0.6}-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications.

  18. Moisture transport and adsorption on silica gel-calcium chloride composite adsorbents

    A measurement of moisture uptake curves in silica gel-calcium composite adsorbents is performed by using the thermal gravimetrical method in a relative vapor pressure range from 0.5 to 0.9 at different temperature levels of 25, 35 and 45 deg. C, respectively. Also, dynamic adsorption curves individually corresponding to the temperature and relative pressure conditions of (25 deg. C, 0.7) (35 deg. C, 0.7) and (35 deg. C, 0.5) have been measured. This experimental study shows that the sorption rate is highest for non-impregnated macroporous silica gel; however, the same silica gel impregnated with calcium chloride has a much greater final water loading. This confirms that composite adsorbents result in a better adsorption performance compared with non-impregnated silica gel, leading to a trade off in finalizing the content of CaCl2 in the composite. Through theoretical analysis on the experimental data, it is found that the saturated adsorption data can be well fitted by the FHH model and the dynamic adsorption data well fitted by the Crank diffusion model, simultaneously yielding the effective solid side mass diffusivities. A comparison with these obtained diffusion coefficients further supports that the mass diffusivity in the composite adsorbent also increases with an increase in temperature, as well as in humidity, but drastically decreases due to the presence of salt inside the matrix pores compared with the non-impregnated host matrix

  19. Ethanol adsorption onto carbonaceous and composite adsorbents for adsorptive cooling system

    The aim of the present paper is the experimental characterization of adsorbent materials suitable for practical applications in adsorption refrigeration systems, employing ethanol as refrigerant. Different commercial activated carbons as well as a properly synthesized porous composite, composed of LiBr inside a silica gel host matrix, have been tested. A complete thermo-physical characterization, comprising nitrogen physi-sorption, specific heat and thermo-gravimetric equilibrium curves of ethanol adsorption over the sorbents, has been carried out. The equilibrium data have been fitted by means of the Dubinin – Astakhov equation. On the basis of the experimental data, a thermodynamic evaluation of the achievable performance of each adsorbent pair has been estimated by calculating the maximum COP (Coefficient of Performance) under typical working boundary conditions for refrigeration and air conditioning applications. The innovative composite material shows the highest thermodynamic performances of 0.64–0.72 for both tested working conditions. Nevertheless, the best carbonaceous material reaches COP value comparable with the synthesized composite. The results have demonstrated the potential of the chosen adsorbents for utilization in adsorption cooling systems. - Highlights: • We studied ethanol adsorption for adsorption cooling systems. • Commercial activated carbons and composite sorbent, LiBr/SiO2, are tested by complete thermo-physical characterization. • A thermodynamic evaluation has been carried out on each working pairs to estimate the performance of a refrigeration cycle

  20. Modeling of fixed-bed column studies for the adsorption of cadmium onto novel polymer-clay composite adsorbent

    Kaolinite clay was treated with polyvinyl alcohol to produce a novel water-stable composite called polymer-clay composite adsorbent. The modified adsorbent was found to have a maximum adsorption capacity of 20,400 ± 13 mg/L (1236 mg/g) and a maximum adsorption rate constant of ∼7.45 x 10-3 ± 0.0002 L/(min mg) at 50% breakthrough. Increase in bed height increased both the breakpoint and exhaustion point of the polymer-clay composite adsorbent. The time for the movement of the Mass Transfer Zone (δ) down the column was found to increase with increasing bed height. The presence of preadsorbed electrolyte and regeneration were found to reduce this time. Increased initial Cd2+ concentration, presence of preadsorbed electrolyte, and regeneration of polymer-clay composite adsorbent reduced the volume of effluent treated. Premodification of polymer-clay composite adsorbent with Ca- and Na-electrolytes reduced the rate of adsorption of Cd2+ onto polymer-clay composite and lowered the breakthrough time of the adsorbent. Regeneration and re-adsorption studies on the polymer-clay composite adsorbent presented a decrease in the bed volume treated at both the breakpoint and exhaustion points of the regenerated bed. Experimental data were observed to show stronger fits to the Bed Depth Service Time (BDST) model than the Thomas model.

  1. Study on the adsorption isosteres of the composite adsorbent CaCl2 and expanded graphite

    A test setup was built to study the adsorption performance of the composite adsorbent used in the adsorption system. The isovolume measurement method is adopted in the test setup to measure the adsorption isosteres of the composite adsorbent and ammonia working pair. The adsorption isosteres are the curves of the adsorption pressures variation with adsorption temperatures at constant adsorption quantity, which are convenient for the calculation of the adsorption heat and selection of the adsorption working pairs. The adsorption heats were calculated according to the adsorption isosteres, three clear crest values indicate that there were three types of reaction during the reaction processes of ammoniate calcium chloride and ammonia. The kinetic model of adsorption isosteres is obtained by the Temkin model, it is useful to estimate the adsorption performance of the working pairs and useful to guide the design of adsorption system.

  2. Characterization of microarc oxidation coatings on pure titanium

    2003-01-01

    The morphology, composition, and phase structure of the oxide coatings produced on the surface of pure titaniumby alternating-current microarc discharge in aluminate solution were investigated by X-ray diffraction and scanning electronmicroscopy. The profiles of the hardness H and the elastic modulus E in the coatings were determined using a nanoindenta-tion method. The concentration distributions of Ti, Al, and O in the coating show that this coating over 30 μm thick containstwo layers: an outer layer and an inner layer. The oxide coating is mainly composed of TiO2 rutile and Al2TiO5 compounds.During oxidation, the temperature in the microarc discharge channel was very high to make the local coating molten. Fromthe surface to the interior of the coating, H and E increase gradually, and then reach maximum values of 9.78 GPa and 176GPa respectively at a distance of 7 μm from the coating/titanium interface. They are also rather high near the interface.

  3. Novel Nanosized Adsorbing Composite Cathode Materials for the Next Generational Lithium Battery

    ZHANG Yong; ZHENG Wei; ZHANG Ping; WANG Lizhen; XIA Tongchi; HU Xinguo; YU Zhenxing

    2007-01-01

    A novel carbon-sulfur nano-composite material was synthesized by heating sublimed sulfur and high surface area activated carbon (HSAAC) under certain conditions. The physical and chemical performances of the novel carbon-sulfur nano-composite were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and X-ray diffraction (XRD). The electrochemical performances of nano-composite were characterized by charge-discharge characteristic, cyclic voltammetry and electrochemical impendence spectroscopy (EIS). The experimental results indicate that the electrochemical capability of nanocomposite material was superior to that of traditional S-containing composite material. The cathode made by carbon-sulfur nano-composite material shows a good cycle ability and a high specific charge-discharge capacity. The HSAAC shows a vital role in adsorbing sublimed sulfur and the polysulfides within the cathode and is an excellent electric conductor for a sulfur cathode and prevents the shuttle behavior of the lithium-sulfur battery.

  4. Bio sorption process for uranium (VI) by using algae-yeast-silica gel composite adsorbent

    Many yeast, algae, bacteria and various aquatic flora are known to be capable of concentrating metal species from dilute aqueous solution. Many researcher have found that non-living biomaterials can be used to accumulate metal ions from environment. In recent studies, mainly two process are used in biosorption experiments. These are the use of free cells and the use of immobilized cells on a solid support. A variety of inert supports have been used to immobilize biomaterials either by adsorption or physical entrapment. This uptake is often considerable and frequently selective, and occurs via a variety of mechanisms including active transport, ion exchange or complexation, and adsorption or inorganic precipitation. Biosorbent may be used as an ion exchange material. Adsorption occurs through interaction of the metal ions with functional groups that are found in the cell wall biopolymers of either living or dead organisms. In this study, the algae-yeast-silica gel composite adsorbent was tested for its ability to recover U(VI) from diluted aqueous solutions. Macro marine algae (Jania rubens.), yeast (Saccharomyces cerevisiae) and silica gel were used to prepare composite adsorbent. The ability of the composite biosorbent to adsorb uranium (VI) from aqueous solution has been studied at different optimized conditions of pH, concentration of U(VI), temperature, contact time and matrix ion effect was also investigated. The adsorption patterns of uranium on the composite biosorbent were investigated by the Langmuir, Freundlich and Dubinin-Radushkhevic isotherms. The thermodynamic parameters such as variation of enthalpy ΔH, variation of entropy ΔS and variation of Gibbs free energy ΔG were calculated. The results suggested that the macro algae-yeast-silica gel composite sorbent is suitable as a new biosorbent material for removal of uranium ions from aqueous solutions

  5. Removal of hydrogen sulfide at ambient conditions on cadmium/GO-based composite adsorbents.

    Florent, Marc; Wallace, Rajiv; Bandosz, Teresa J

    2015-06-15

    Cadmium-based materials with various hydroxide to carbonate ratios and their composites with graphite oxide were synthesized by a fast and simple precipitation procedure and then used as H2S adsorbents at ambient conditions in the dark or upon a visible light exposure. The structural properties and chemical features of the adsorbents were analyzed before and after hydrogen sulfide adsorption. The results showed that the high ratio of hydroxide to carbonate led to an improved H2S adsorption capacity. In moist conditions cadmium hydroxide was the best adsorbent. Moreover, it showed photoactive properties. While the incorporation of a graphene-based phase slightly decreased the extent of the improvement in the H2S adsorption capacity in moist conditions caused by photoactivity, its presence in the composites enhanced the performance in dry conditions. This was linked to photoactivity of CdS that can split H2S resulting in the formation of water in the system. The graphene-based phase enhanced the electron transfer and delayed the recombination of photoinduced charges. Carbonate-based materials showed a very good adsorption capacity in dark conditions in the presence of moisture. Upon the light exposure, CdS likely photocatalyzes the reduction of carbonate ions to formates/formaldehydes. Their deposition on the surface limits the number of sites available to H2S adsorption. PMID:25792480

  6. Protective oxide coating on the surface of steel St20

    The authors investigated the stability of oxide coatings on the surface of pearlitic steel 20 at 90 degree C in an aqueous medium. The article examines the influence of the flow rate and of the presence of corrosion products of iron on the protective effect of the oxide coating. On the basis of the results of the investigations obtained with the aid of the radionuclides 59Fe, 54Mn, 137Cs the conclusion is reached that the oxide coating is not restored and does not peel off. The assumption is voiced that a layer of hydroxide forms between the metal and the oxide coating

  7. Photocatalytic Iron Oxide Coatings Produced by Thermal Spraying Process

    Navidpour, A. H.; Salehi, M.; Amirnasr, M.; Salimijazi, H. R.; Azarpour Siahkali, M.; Kalantari, Y.; Mohammadnezhad, M.

    2015-12-01

    Recently, hematite coatings with semiconductor properties have received attention for photocatalytic applications. In this study, plasma and flame spraying techniques were used for hematite deposition on 316 stainless steel plates. X-ray diffraction was used for phase composition analysis, and methylene blue was used as an organic pollutant to evaluate the photocatalytic activity of thermally sprayed coatings. The results showed that all these coatings could act under visible-light irradiation but the one deposited by flame spraying at 20 cm stand-off distance showed the highest photocatalytic activity. The results showed that wavelength of the light source and pH of the solution affected the photocatalytic activity significantly. It was also shown that thermally sprayed iron oxide coatings could have a high photo-absorption ability, which could positively affect the photocatalytic activity.

  8. Synthesis of bio-active titanium oxide coatings stimulated by electron-beam plasma

    Vasilieva Tatiana

    2014-11-01

    Full Text Available Advantages of the electron-beam plasma (EBP for production of bioactive titanium oxide coatings were experimentally studied. The coatings were synthesized in EBP of oxygen on the surface of plane titanium substrates. A number of analytical techniques were used to characterize morphology, chemical composition, and structure of the synthesized titanium oxide. The analysis showed the titanium oxide (IV in the rutile form to predominate in the coatings composition.

  9. Synthesis of bio-active titanium oxide coatings stimulated by electron-beam plasma

    Vasilieva Tatiana; Sokolov Igor; Sigarev Andrey; Tun Win Aung

    2014-01-01

    Advantages of the electron-beam plasma (EBP) for production of bioactive titanium oxide coatings were experimentally studied. The coatings were synthesized in EBP of oxygen on the surface of plane titanium substrates. A number of analytical techniques were used to characterize morphology, chemical composition, and structure of the synthesized titanium oxide. The analysis showed the titanium oxide (IV) in the rutile form to predominate in the coatings composition.

  10. Alumina-Activated Carbon Composite as Adsorbent of Procion Red Dye from Wastewater Songket Industry

    Poedji Loekitowati Hariani

    2015-03-01

    Full Text Available Alumina-activated carbon composite has been synthesized and studied for adsorption procion red dye. Composite was prepared by precipitation method aluminium hydroxide on the surface of activated carbon followed by calcinations. The Fourier transform Infra Red (FTIR, Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS and Brunaeur Emmet Teller (BET surface are being used to characterize the adsorbent. Batch adsorption experiments were carried out for the adsorption of procion red dye. Effect of the mass of composite, stirrer speed, contact times and pH of the solution on the adsorption capacity were studied. The obtained optimum conditions applied to adsorp of procion red dye from wastewater songket industry. The result showed that the adsorption optimum at mass of alumina-activated carbon composite 0.1 g, stirrer speed 150 rpm, contact times 2 hours at pH of the solution 9. The adsorption isotherm data according to Langmuir isotherm. The alumina-activated carbon composite can be removal of procion red dye from wastewater songket industry with effectiveness adsorption of 88.21 %.

  11. Biocompatibility of Ir/Ti-oxide coatings: Interaction with platelets, endothelial and smooth muscle cells

    Habibzadeh, Sajjad; Li, Ling; Omanovic, Sasha; Shum-Tim, Dominique; Davis, Elaine C.

    2014-05-01

    Applying surface coatings on a biomedical implant is a promising modification technique which can enhance the implant's biocompatibility via controlling blood constituents- or/and cell-surface interaction. In this study, the influence of composition of IrxTi1-x-oxide coatings (x = 0, 0.2, 0.4, 0.6, 0.8, 1) formed on a titanium (Ti) substrate on the responses of platelets, endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. The results showed that a significant decrease in platelet adhesion and activation was obtained on Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, rendering the surfaces more blood compatible, in comparison to the control (316L stainless steel, 316L-SS) and other coating compositions. Further, a substantial increase in the EC/SMC surface count ratio after 4 h of cell attachment to the Ir0.2Ti0.8-oxide and Ir0.4Ti0.6-oxide coatings, relative to the 316L-SS control and the other coating compositions, indicated high potential of these coatings for the enhancement of surface endothelialization. This indicates the capability of the corresponding coating compositions to promote EC proliferation on the surface, while inhibiting that of SMCs, which is important in cardiovascular stents applications.

  12. Efficient removal of Eu(III) from aqueous solutions using super-adsorbent of bentonite-polyacrylamide composites

    The bentonite has been studied extensively to preconcentrate radionuclides from aqueous solutions, however, the low sorption capacity limits it application in real work. Herein, bentonite embedded in the polyacrylamide (PAAm) gels is synthesized and used as a novel adsorbent for the removal of Eu(III) from aqueous solutions. The bentonite-PAAm composites show much higher sorption capacity for Eu(III) preconcentration than bare bentonite. The bentonite-PAAm composites can be used as super-adsorbent for the removal of Eu(III) from aqueous solution in radioactive pollution cleanup. (author)

  13. Synthesis, structural and mechanical characterization of sputtered tungsten oxide coatings

    Tungsten oxide coatings were deposited without substrate bias by DC reactive magnetron sputtering of a tungsten target using oxygen as reactive gas. By tuning the partial pressure of oxygen (p O2/p Ar) between 0 and 4, the oxygen content of the films was changed from 0 to 75 at.%. The structure of the films (investigated by X-ray diffraction) depends on their oxygen content. For low oxygen contents, the α-W and β-W3O phases were observed ( 75 at.%, a nanocrystalline (WO3) structure was reached. The hardness and Young's modulus were evaluated by depth sensing indentation. The decrease in hardness followed the four different ranges of chemical compositions accordingly, from ∼ 23 GPa for pure W down to ∼ 7 GPa for WO3 films. A similar behaviour was observed for the Young's modulus, which ranged from 450 GPa to 150 GPa. The cohesion/adhesion of the films were investigated using a scratch-test apparatus. These coatings displayed a low adhesion (critical load, L c < 15 N) to the steel substrate because the depositions were carried out intentionally without an adhesion interfacial layer

  14. Large charge-storage-capacity iridium/ruthenium oxide coatings as promising material for neural stimulating electrodes

    Ullah, Nehar, E-mail: nehar.ullah@mail.mcgill.ca; Omanovic, Sasha

    2015-06-01

    Electrochemical and topographical/structural/morphological properties of thermally prepared Ir/Ru-oxide coatings of various compositions formed on a Ti substrate were investigated. An apparent electrochemically active surface area (AEASA) and charge storage capacity (CSC) were determined. The freshly-prepared Ir{sub 0.6}Ru{sub 0.4}-oxide coating was found to offer the largest AEASA and CSC; however, after exposing all the coatings to prolonged extreme electrochemical cycling in phosphate buffered saline pH 7.4, within a 5 V potential window (“torturing”), the Ir{sub 0.8}Ru{sub 0.2}-oxide coating yielded both the largest AEASA (1540 cm{sup 2}) and CSC (27 mC cm{sup −2}). Under the same experimental condition, the Ir{sub 0.8}Ru{sub 0.2}-oxide coating was found to yield by a 56% higher CSC than the current state-of-the-art neural stimulating electrode, Ir-oxide, making it a good candidate for further optimization and possible application as a neural stimulating electrode. - Highlights: • Ir/Ru-oxide coatings were formed thermally on a Ti substrate. • Electrochemical properties of Ir/Ru-oxide coatings were investigated. • Ir{sub 0.8}–Ru{sub 0.2}-oxide yielded highest apparent electrochemically-active surface area. • Ir{sub 0.8}–Ru{sub 0.2}-oxide yielded highest charge storage capacity. • Charge storage capacity is by 56% higher than current state-of-the-art, Ir-oxide.

  15. Bacterial adhesion on amorphous and crystalline metal oxide coatings

    Almaguer-Flores, Argelia [Facultad de Odontología, División de Estudios de Posgrado e Investigación, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Silva-Bermudez, Phaedra, E-mail: suriel21@yahoo.com [Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa, Instituto Nacional de Rehabilitación, Calzada México-Xochimilco No. 289, Col. Arenal de Guadalupe, 14389 México D.F. (Mexico); Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Galicia, Rey; Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico)

    2015-12-01

    Several studies have demonstrated the influence of surface properties (surface energy, composition and topography) of biocompatible materials on the adhesion of cells/bacteria on solid substrates; however, few have provided information about the effect of the atomic arrangement or crystallinity. Using magnetron sputtering deposition, we produced amorphous and crystalline TiO{sub 2} and ZrO{sub 2} coatings with controlled micro and nanoscale morphology. The effect of the structure on the physical–chemical surface properties was carefully analyzed. Then, we studied how these parameters affect the adhesion of Escherichia coli and Staphylococcus aureus. Our findings demonstrated that the nano-topography and the surface energy were significantly influenced by the coating structure. Bacterial adhesion at micro-rough (2.6 μm) surfaces was independent of the surface composition and structure, contrary to the observation in sub-micron (0.5 μm) rough surfaces, where the crystalline oxides (TiO{sub 2} > ZrO{sub 2}) surfaces exhibited higher numbers of attached bacteria. Particularly, crystalline TiO{sub 2}, which presented a predominant acidic nature, was more attractive for the adhesion of the negatively charged bacteria. The information provided by this study, where surface modifications are introduced by means of the deposition of amorphous or crystalline oxide coatings, offers a route for the rational design of implant surfaces to control or inhibit bacterial adhesion. - Highlights: • Amorphous (a) and crystalline (c) TiO{sub 2} and ZrO{sub 2} coatings were deposited. • The atomic ordering influences the coatings surface charge and nano-topography. • The atomic ordering modifies the bacterial adhesion for the same surface chemistry. • S. aureus adhesion was lower on a-TiO{sub 2} and a-ZrO{sub 2} than on their c-oxide counterpart. • E. coli adhesion on a-TiO{sub 2} was lower than on the c-TiO{sub 2}.

  16. The Overcoat Oil Lubrication of Microarc Oxidation Coating on Al Alloy by Liquid Plasma Technique

    LUO Zhuang-zi; ZHANG Zhao-zhu; LIU Wei-ming; WANG Wen-jing; TIAN Jun

    2004-01-01

    Ceramic coatings were deposited on 2Al2 alloy with a 100 kW micro-arc oxidation equipment consisting of a potential adjustable ac power supply and alkali electrolyte. The structure of the micro-arc oxidiation coatings was examined using scanning electron microscopy and transmission electron microscopy. The tribological properties of the coatings sliding against steel under the drop and adsorption lubrication of liquid paraffin were evaluated with a Timken tester. The lower friction coefficient of 0.14 and longer wear life of 2450 m of overcoat were observed for the polished micro-arc oxidation coating of 180μm thick at a sliding speed 2. 50 m/s and load 1500 N. This is because the coating has an interlayer of suitable porosity and thickness, which helps to improve the deposition of lubricants and endure the higher load. In other words, the oil is able to adsorb in the porous holes of the overcoat and provided the lubrication of micro reservoir during friction, and the compact and relatively hard interlayer of oxidation coating is able to support heavy load and prevent the oil lubricating film from damage.

  17. An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent

    Haldorai, Yuvaraj; Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr

    2014-02-15

    We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS–MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

  18. An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: A novel reusable adsorbent

    We report a novel multi-functional magnesium oxide (MgO) immobilized chitosan (CS) composite was prepared by chemical precipitation method. The CS–MgO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and zeta potential. The composite was applied as a novel adsorbent for removal of methyl orange model dye and the effect of adsorbent dosage, pH and contact time were studied. The adsorption kinetics followed a pseudo second order reaction. The adsorbent efficiency was unaltered even after five cycles of reuse. In addition, the composite exhibited a superior antibacterial efficacy of 93% within 24 h against Escherichia coli as measured by colony forming units. Based on the data of present investigation the composite being a biocompatible, eco-friendly and low-cost adsorbent with antibacterial activity could find potential applications in variety of fields and in particular environmental applications.

  19. Electrochemical combustion of indigo at ternary oxide coated titanium anodes

    María I. León

    2014-12-01

    Full Text Available The film of iridium and tin dioxides doped with antimony (IrO2-SnO2–Sb2O5 deposited on a Ti substrate (mesh obtained by Pechini method was used for the formation of ·OH radicals by water discharge. Detection of ·OH radicals was followed by the use of the N,N-dimethyl-p-nitrosoaniline (RNO as a spin trap. The electrode surface morphology and composition was characterized by SEM-EDS. The ternary oxide coating was used for the electrochemical combustion of indigo textile dye as a model organic compound in chloride medium. Bulk electrolyses were then carried out at different volumetric flow rates under galvanostatic conditions using a filter-press flow cell. The galvanostatic tests using RNO confirmed that Ti/IrO2-SnO2-Sb2O5 favor the hydroxyl radical formation at current densities between 5 and 7 mA cm-2, while at current density of 10 mA cm-2 the oxygen evolution reaction occurs. The indigo was totally decolorized and mineralized via reactive oxygen species, such as (·OH, H2O2, O3 and active chlorine formed in-situ at the Ti/IrO2-SnO2-Sb2O5 surface at volumetric flow rates between 0.1-0.4 L min-1 and at fixed current density of 7 mA cm-2. The mineralization of indigo carried out at 0.2 L min-1 achieved values of 100 %, with current efficiencies of 80 % and energy consumption of 1.78 KWh m-3.

  20. Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-25

    Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. PMID:25265524

  1. Water-insoluble sericin/β-cyclodextrin/PVA composite electrospun nanofibers as effective adsorbents towards methylene blue.

    Zhao, Rui; Wang, Yong; Li, Xiang; Sun, Bolun; Jiang, Ziqiao; Wang, Ce

    2015-12-01

    A novel water-insoluble sericin/β-cyclodextrin/poly (vinyl alcohol) composite nanofiber adsorbent was prepared by electrospinning and followed by thermal crosslinking for removal of cationic dye methylene blue from aqueous solution. Fourier transform infrared spectroscopy and solubility experiments confirmed that sericin and β-cyclodextrin were incorporated into the nanofibers and the crosslinking reaction occurred successfully. Kinetics, isotherms and thermodynamics analysis were studied for adsorption of methylene blue. The adsorption process is better fitted with the pseudo-second-order model and Langmuir isotherm model. The maximum adsorption capacities are 187.97, 229.89, and 261.10mg/g at the temperatures 293, 313 and 333 K, respectively. Thermodynamic parameters showed that methylene blue adsorption was endothermic and spontaneous. In addition, the fiber membrane adsorbent could be easily separated from dye solution and showed high recyclable removal efficiency. All these results suggest that crosslinked sericin/β-cyclodextrin/poly(vinyl alcohol) composite nanofibers could be potential recyclable adsorbents in dye wastewater treatment. PMID:26433644

  2. A DRIFTS STUDY OF THE MORPHOLOGY AND SURFACE ADSORBATE COMPOSITION OF AN OPERATING METHANOL SYNTHESIS CATALYST

    BAILEY, S; FROMENT, GF; SNOECK, JW; WAUGH, KC

    1995-01-01

    The nature of the species adsorbed on a Cu/ZnO/Al2O3 catalyst while it was producing methanol has been elucidated in this study using DRIFTS. The species are carbonates, formate, CO, oxygen atoms (similar to 2% of a monolayer) and methoxy on the Cu and methoxy on the ZnO. The frequencies observed fo

  3. Preparation of polyacrylonitrile-potassium cobalt/titanium hexacyanoferrate (Ⅱ) spherical composite adsorbents and their adsorption properties for Cs+

    Polyacrylonitrile-potassium cobalt/titanium hexacyanoferrate (Ⅱ) spherical composite adsorbents (PAN-KCoCF and PAN-KTiCF) were prepared to remove cesium ions from aqueous solution. The effects of contact time, pH, competition ions and initial cesium concentration on cesium sorption were investigated via batch experiments. The adsorptive kinetics and isotherms were analyzed. The characterization of PAN-KCoCF and PAN-KTiCF were performed by SEM, FT-IR, XRD, etc. The results show that the cesium sorption of PAN-KCoCF and PAN-KTiCF can reach equilibrium after about 16 h. With the increase of pH, the cesium sorption of PAN-KTiCF increases fast at first and maintains at an almost constant value, while the cesium sorption of PAN-KCoCF isn't almost affected. Compared with PAN-KTiCF, the cesium sorption of PAN-KCoCF is more selective when K+, Na+, NH4+, Ca2+ or Mg2+ is added to solution. The sorption kinetics of two adsorbents for Cs+ can be described by pseudo second-order equation, and the sorption rate is mainly controlled by surface adsorption. The sorption of two adsorbents for cesium is monolayer adsorption, and the sorption data can be interpreted in terms of Langmuir isotherm. The saturated adsorption capacities of PAN-KCoCF and PAN-KTiCF are 128.370 mg/g and 278.552 mg/g, respectively. (authors)

  4. Effects of MAR-M247 substrate (modified) composition on coating oxidation coating/substrate interdiffusion. M.S. Thesis. Final Report; [protective coatings for hot section components of gas turbine engines

    Pilsner, B. H.

    1985-01-01

    The effects of gamma+gamma' Mar-M247 substrate composition on gamma+beta Ni-Cr-Al-Zr coating oxidation and coating/substrate interdiffusion were evaluated. These results were also compared to a prior study for a Ni-Cr-Al-Zr coated gamma Ni-Cr-Al substrate with equivalent Al and Cr atomic percentages. Cyclic oxidation behavior at 1130 C was investigated using change in weight curves. Concentration/distance profiles were measured for Al, Cr, Co, W, and Ta. The surface oxides were examined by X-ray diffraction and scanning electron microscopy. The results indicate that variations of Ta and C concentrations in the substrate do not affect oxidation resistance, while additions of grain boundary strengthening elements (Zr, Hf, B) increase oxidation resistance. In addition, the results indicate that oxidation phenomena in gamma+beta/gamma+gamma' Mar-M247 systems have similar characteristics to the l gamma+beta/gamma Ni-Cr-Al system.

  5. Chitosan/Graphene Oxide Composite as an Effective Adsorbent for Reactive Red Dye Removal.

    Guo, Xiaoqing; Qu, Lijun; Tian, Mingwei; Zhu, Shifeng; Zhang, Xiansheng; Tang, Xiaoning; Sun, Kaikai

    2016-07-01

    Chitosan, modified with different dosages of graphene oxide (GO) and reduced graphene oxide (rGO), was first prepared, and its adsorption capacity for reactive red (RR) dye in aqueous solutions was investigated, in this paper. The structure and morphology of the adsorbents were characterized by FT-IR, XRD, SEM, EDX, BET, and TGA. The effect of varying parameters (pH, temperature, adsorbent loading, and contact time) was also investigated. The maximum adsorption capacity based on the Langmuir model was found to be 32.16 mg/g. In addition, experimental kinetic data were analyzed by the psuedo-first order and psuedo-second order equation models. The psuedo-second order model proved to be the best model for the adsorption system, which suggested that adsorption might be controlled by the chemical rate-limiting step through sharing of electrons or by covalent forces. PMID:27329054

  6. As(V) adsorption onto nanoporous titania adsorbents (NTAs): effects of solution composition.

    Han, Dong Suk; Batchelor, Bill; Park, Sung Hyuk; Abdel-Wahab, Ahmed

    2012-08-30

    This study has focused on developing two nanoporous titania adsorbents (NTA) to enhance removal efficiency of adsorption process for As(V) by characterizing the effects of pH and phosphate concentration on their sorption capacities and behaviors. One type of adsorbent is a mesoporous titania (MT) solid phase and the other is group of a highly ordered mesoporous silica solids (SBA-15) that can incorporate different levels of reactive titania sorption sites. Microscopic analysis showed that Ti((25))-SBA-15 (Ti/SBA=0.25 g/g) had titania nanostructured mesopores that do not rupture the highly ordered hexagonal silica framework. However, MT has disordered, wormhole-like mesopores that are caused by interparticle porosity. Adsorption experiments showed that Ti((25))-SBA-15 had a greater sorption capacity for As(V) than did Ti((15))-SBA-15 or Ti((35))-SBA-15 and the amount of As(V) adsorbed generally decreased as pH increased. Higher removal of As(V) was observed with Ti((25))-SBA-15 than with MT at pH 4, but MT had higher removals at higher pH (7, 9.5), even though MT has a lower specific surface area. However, in the presence of phosphate, MT showed higher removal of As(V) at low pH rather than did Ti((25))-SBA-15. As expected, the NTAs showed very fast sorption kinetics, but they followed a bi-phasic sorption pattern. PMID:22727482

  7. Investigation of anodic oxide coatings on zirconium after heat treatment

    Highlights: • Oxide layers prepared via PEO of zirconium were subjected to heat treatment. • Surface characteristics were determined for the obtained oxide coatings. • Heat treatment led to the partial destruction of the anodic oxide layer. • Pitting corrosion resistance of zirconium was improved after the modification. - Abstract: Herein, results of heat treatment of zirconium anodised under plasma electrolytic oxidation (PEO) conditions at 500–800 °C are presented. The obtained oxide films were investigated by means of SEM, XRD and Raman spectroscopy. The corrosion resistance of the zirconium specimens was evaluated in Ringer's solution. A bilayer oxide coatings generated in the course of PEO of zirconium were not observed after the heat treatment. The resulting oxide layers contained a new sublayer located at the metal/oxide interface is suggested to originate from the thermal oxidation of zirconium. The corrosion resistance of the anodised metal was improved after the heat treatment

  8. Investigation of anodic oxide coatings on zirconium after heat treatment

    Sowa, Maciej [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Dercz, Grzegorz [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty Street 1 A, 41-500 Chorzów (Poland); Suchanek, Katarzyna [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

    2015-08-15

    Highlights: • Oxide layers prepared via PEO of zirconium were subjected to heat treatment. • Surface characteristics were determined for the obtained oxide coatings. • Heat treatment led to the partial destruction of the anodic oxide layer. • Pitting corrosion resistance of zirconium was improved after the modification. - Abstract: Herein, results of heat treatment of zirconium anodised under plasma electrolytic oxidation (PEO) conditions at 500–800 °C are presented. The obtained oxide films were investigated by means of SEM, XRD and Raman spectroscopy. The corrosion resistance of the zirconium specimens was evaluated in Ringer's solution. A bilayer oxide coatings generated in the course of PEO of zirconium were not observed after the heat treatment. The resulting oxide layers contained a new sublayer located at the metal/oxide interface is suggested to originate from the thermal oxidation of zirconium. The corrosion resistance of the anodised metal was improved after the heat treatment.

  9. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Highlights: ► Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. ► Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. ► Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  10. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  11. Mesoporous silica/polyacrylamide composite: Preparation by UV-graft photopolymerization, characterization and use as Hg(II) adsorbent

    Saad, Ali; Bakas, Idriss; Piquemal, Jean-Yves; Nowak, Sophie; Abderrabba, Manef; Chehimi, Mohamed M.

    2016-03-01

    MCM-41 ordered mesoporous silica was prepared, aminosilanized and grafted with polyacrylamide (PAAM) through in situ radical photopolymerization process. The resulting composite, denoted PAAM-NH2-MCM-41, the calcined and silanized reference MCM-41s were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N2 physisorption at 77 K. These complementary techniques brought strong supporting evidence for the silanization process followed by PAAM grafting. The surface composition was found to be PAAM-rich as judged by XPS. The composite was then employed for the uptake of Hg(II) from aqueous solutions. Adsorption was monitored versus pH, time, and temperature. The maximum adsorption capacity at 25 °C and pH 5.2 was 177 mg g-1. Kinetically, the equilibrium was reached within 60 min for a 100 mg L-1 mercury solution. The adsorption of Hg(II) on PAAM-NH2-MCM-41 composites followed second order kinetics. Thermodynamic parameters suggested that the favorable adsorption process is exothermic in nature and the adsorption is ascribed to a decrease in the degree of freedom of adsorbed ions which results in the entropy change. This work conclusively shows that mesoporous silica-polymer hybrid metal ion adsorbents (with robust silica-polymer interface) can be prepared in a simple way by in situ radical photopolymerization in the presence of aminosilanized silica acting as a support and a macro-hydrogen donor simultaneously.

  12. Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

    DENG Shu-hao; YI Dan-qing; GONG Zhu-qing; SU Yu-chang

    2005-01-01

    In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr6+ and PO43-, constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating's structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgA12O4 and MgO, and the minor phases are Al2O3 and SiO2 when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.

  13. Electron Beam Plasma Application for Synthesis of Bioactive Titanium Oxide Coatings

    Vasilieva, T. M.; Sokolov, I. V.; Balakin, K. V.

    2015-03-01

    Prospective bio-medical applications of the electron-beam plasma (EBP) were experimentally studied. The EBP-treated titanium samples were investigated from the point of view of their bio-compatibility. The titanium oxide coatings were synthesized in the EBP of oxygen on the surface of plane titanium substrates and on the inner surface of the titanium tubes. The EBB-treatment was able to signifantly improve the surface uniformity and roughness. Titanium oxide TiO2 (IV) in the rutile form predominated in the coatings composition The bioactivity of synthesized TiO2-coatings was characterized by the water contact angle measurements and by the ability to precipitate hydroxyapatite from the model solution which simulated the composition of the body fluid. The studies showed the samples with plasmachemically synthesized TiO2-coatings to be more hydrophilic than untreated titanium and to precipitate hydroxyapatite on their surface effectively.

  14. Performance of magnetic activated carbon composite as peroxymonosulfate activator and regenerable adsorbent via sulfate radical-mediated oxidation processes.

    Oh, Wen-Da; Lua, Shun-Kuang; Dong, Zhili; Lim, Teik-Thye

    2015-03-01

    Magnetic activated carbon composite (CuFe2O4/AC, MACC) was prepared by a co-precipitation-calcination method. The MACC consisted of porous micro-particle morphology with homogeneously distributed CuFe2O4 and possessed high magnetic saturation moment (8.1 emu g(-1)). The performance of MACC was evaluated as catalyst and regenerable adsorbent via peroxymonosulfate (PMS, Oxone(®)) activation for methylene blue (MB) removal. Optimum CuFe2O4/AC w/w ratio was 1:1.5 giving excellent performance and can be reused for at least 3 cycles. The presence of common inorganic ions, namely Cl(-) and NO3(-) did not exert significant influence on MB degradation but humic acid decreased the MB degradation rate. As a regenerable adsorbent, negligible difference in regeneration efficiency was observed when a higher Oxone(®) dosage was employed but a better efficiency was obtained at a lower MACC loading. The factors hindering complete MACC regeneration are MB adsorption irreversibility and AC surface modification by PMS making it less favorable for subsequent MB adsorption. With an additional mild heat treatment (150 °C) after regeneration, 82% of the active sites were successfully regenerated. A kinetic model incorporating simultaneous first-order desorption, second-order adsorption and pseudo-first order degradation processes was numerically-solved to describe the rate of regeneration. The regeneration rate increased linearly with increasing Oxone(®):MACC ratio. The MACC could potentially serve as a catalyst for PMS activation and regenerable adsorbent. PMID:25463211

  15. Hydrophilicity of titanium oxide coatings with the addition of silica

    This work investigated hydrophilicity between titanium oxide coatings with and without addition of silica. A sol of titania and silica was prepared for sol-gel coating. The sol of titanium oxide is aqueous, and the mixed sol is transparent with a pH value of 8.0. Coating was prepared by spraying mixed sol over a heated substrate. The titanium oxide sol was prepared by using an inorganic titanium salt. A silica sol was then added to titanium oxide sol obtain the mixed sol. Thickness of the coatings were between 20 and 80 nm. The sols were characterized by IR spectroscopy. AFM was used to investigate the coating surface structure and roughness. The crystalline size of coating surface for the mixed oxides was little greater than for the pure titanium oxide. The crystalline phase was investigated using X-ray diffraction. The hydrophilicity of coatings was studied with UV and sunlight exposure and by measurement of contact angle change of droplets of water. Through the investigation of change of contact angle and water droplets on the surface after UV exposure and sunlight radiation, it can be concluded that hydrophilicity of mixed coatings with low temperature heat-treatment of titanium oxide and silica are much better than a pure titanium oxide coating. This effect makes for an improved self-cleaning coating

  16. Efficient adsorption of both methyl orange and chromium from their aqueous mixtures using a quaternary ammonium salt modified chitosan magnetic composite adsorbent.

    Li, Kun; Li, Pei; Cai, Jun; Xiao, Shoujun; Yang, Hu; Li, Aimin

    2016-07-01

    A quaternary ammonium salt modified chitosan magnetic composite adsorbent (CS-CTA-MCM) was prepared by combination of Fe3O4 nanoparticles. Various techniques were used to characterize the molecular structure, surface morphology, and magnetic feature of this composite adsorbent. CS-CTA-MCM was employed for the removal of Cr(VI) and methyl orange (MO), an anionic dye, from water in respective single and binary systems. Compared with chitosan magnetic adsorbent (CS-MCM) without modification, CS-CTA-MCM shows evidently improved adsorption capacities for both pollutants ascribed to the additional quaternary ammonium salt groups. Based on the adsorption equilibrium study, MO bears more affinity to CS-CTA-MCM than Cr(VI) causing a considerable extent of preferential adsorption of dye over metal ions in their aqueous mixture. However, at weak acidic solutions, Cr(VI) adsorption is evidently improved due to more efficient Cr(VI) forms, i.e. dichromate and monovalent chromate, binding to this chitosan-based adsorbent. Thus chromium could be efficient removal together with MO at suitable pH conditions. The adsorption isotherms and kinetics indicate that adsorptions of Cr(VI) and MO by CS-CTA-MCM both follow a homogeneous monolayer chemisorption process. This magnetic adsorbent after saturated adsorption could be rapidly separated from water and easily regenerated using dilute NaOH aqueous solutions then virtually reused with little adsorption capacity loss. PMID:27060639

  17. Novel low density granular adsorbents - properties of a composite matrix from zeolitisation of vermiculite.

    Johnson, Christopher D; Worrall, Fred

    2007-06-01

    This paper reports the preparation and properties of a new low density granular absorbent material based on a zeolite/vermiculite composite. The composite prepared addresses a number of important issues relating to the use of zeolites in environmental and waste management applications. The material prepared has large particle size due to binderless adhesion of zeolite crystals within the protective lamellar matrix provided by the vermiculite granule. Additionally, the porous nature of new material ensures that it outperforms natural zeolite grains in ion-exchange tests. The material was shown to have a low bulk density (0.75 g cm(-3)) adding the benefit that the majority of grains float on water for over 15 h. The conclusion of the study is that the use of composite matrices enable the preparation of materials which show the physical properties of the host, (e.g., granular and low density), whilst maintaining the powder-like properties (e.g., high ion-exchange and small crystal size) of the active component. The resulting material can be easily handled and separated from aqueous waste streams using either flotation or exploiting its granular nature. PMID:17368511

  18. A novel modified graphene oxide/chitosan composite used as an adsorbent for Cr(VI) in aqueous solutions.

    Zhang, Li; Luo, Hanjin; Liu, Peipei; Fang, Wei; Geng, Junjie

    2016-06-01

    A novel adsorbent for removal of hexavalent chromium (Cr(VI)) from aqueous solutions has been successfully prepared by modifying graphene oxide/chitosan composite with disodium ethylenediaminetetraacetate (EDTA-2Na) (GEC). This modified composite was characterized by various technologies; including scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Batch adsorption experiments were carried out to evaluate the adsorption of Cr(VI) by GEC under different conditions. The results indicate that the adsorption of Cr(VI) on GEC was highly pH-dependent, with the highest adsorption capacity (86.17mg/g) occurring at pH 2. The kinetics of adsorption exhibited pseudo-second-order behavior. The adsorption data were well described by the Freundlich isotherm model. The adsorption capacity increased with increasing temperature. The calculated thermodynamic parameters indicate that the adsorption is a spontaneous, endothermic and feasible process. The further regeneration experiments showed the adsorption capacity of GEC for Cr(VI) decreased 5% after 7 times reuse, indicating the potential of the as-prepared material for practical application. PMID:26993532

  19. Hybrid Adsorptive and Oxidative Removal of Natural Organic Matter Using Iron Oxide-Coated Pumice Particles

    Sehnaz Sule Kaplan Bekaroglu

    2016-01-01

    Full Text Available The aim of this work was to combine adsorptive and catalytic properties of iron oxide surfaces in a hybrid process using hydrogen peroxide and iron oxide-coated pumice particles to remove natural organic matter (NOM in water. Experiments were conducted in batch, completely mixed reactors using various original and coated pumice particles. The results showed that both adsorption and catalytic oxidation mechanisms played role in the removal of NOM. The hybrid process was found to be effective in removing NOM from water having a wide range of specific UV absorbance values. Iron oxide surfaces preferentially adsorbed UV280-absorbing NOM fractions. Furthermore, the strong oxidants produced from reactions among iron oxide surfaces and hydrogen peroxide also preferentially oxidized UV280-absorbing NOM fractions. Preloading of iron oxide surfaces with NOM slightly reduced the further NOM removal performance of the hybrid process. Overall, the results suggested that the tested hybrid process may be effective for removal of NOM and control disinfection by-product formation.

  20. Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability

    Velmurugan Thavasi; Lala, Neeta L.; Seeram Ramakrishna

    2009-01-01

    We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature ...

  1. Plasma-Sprayed Refractory Oxide Coatings on Silicon-Base Ceramics

    Tewari, Surendra

    1997-01-01

    Silicon-base ceramics are promising candidate materials for high temperature structural applications such as heat exchangers, gas turbines and advanced internal combustion engines. Composites based on these materials are leading candidates for combustor materials for HSCT gas turbine engines. These materials possess a combination of excellent physical and mechanical properties at high temperatures, for example, high strength, high toughness, high thermal shock resistance, high thermal conductivity, light weight and excellent oxidation resistance. However, environmental durability can be significantly reduced in certain conditions such as when molten salts, H2 or water vapor are present. The oxidation resistance of silicon-base materials is provided by SiO2 protective layer. Molten salt reacts with SiO2 and forms a mixture of SiO2 and liquid silicate at temperatures above 800C. Oxygen diffuses more easily through the chemically altered layer, resulting in a catastrophic degradation of the substrate. SiC and Si3N4 are not stable in pure H2 and decompose to silicon and gaseous species such as CH4, SiH, SiH4, N2, and NH3. Water vapor is known to slightly increase the oxidation rate of SiC and Si3N4. Refractory oxides such as alumina, yttria-stabilized zirconia, yttria and mullite (3Al2O3.2SiO2) possess excellent environmental durability in harsh conditions mentioned above. Therefore, refractory oxide coatings on silicon-base ceramics can substantially improve the environmental durability of these materials by acting as a chemical reaction barrier. These oxide coatings can also serve as a thermal barrier. The purpose of this research program has been to develop refractory oxide chemical/thermal barrier coatings on silicon-base ceramics to provide extended temperature range and lifetime to these materials in harsh environments.

  2. Effect of fly ash addition on the removal of hydrogen sulfide from biogas and air on sewage sludge-based composite adsorbents.

    Seredych, Mykola; Strydom, Christien; Bandosz, Teresa J

    2008-01-01

    Desulfurization adsorbents were prepared from the mixtures of various compositions of New York City sewage sludge and fly ashes from SASOL, South Africa, by pyrolysis at 950 degrees C. The resulting materials were used as adsorbents of hydrogen sulfide from simulated dry digester gas mixture or moist air. The adsorbents before and after H(2)S removal were characterized using adsorption of nitrogen, elemental analysis, pH measurements, XRF, XRD, and thermal analysis. It was found that the addition of fly ash decreases the desulfurization capacity in comparison with the sewage sludge-based materials. The extent of this decrease depends on the type of ash, its content and the composition of challenging gas. Although the presence of CO(2) deactivates some adsorption sites to various degrees depending on the sample composition, the addition of ashes has a more detrimental effect when the adsorbents are used to remove hydrogen sulfide from air. This is likely the result of hydrophobicity of ashes since the H(2)S removal capacity was found to be strongly dependent on the reactivity towards water/water adsorption. On the other hand, the addition of ashes strongly decreases the porosity of materials where sulfur, as a product of hydrogen sulfide oxidation, can be stored. PMID:17935967

  3. Composite membranes modified with recognition-able nanobeads as potential adsorbers for purification of biological fluids.

    Silvestri, D; Cristallini, C; Borrelli, C; Barbani, N; Giusti, P; Ciardelli, G

    2007-01-01

    Therapeutic approaches in the clinical field require advanced properties for delivery or recognition of clinical species. The molecular imprinting method allows selective cavities to be inserted into a polymeric material built "around" a stamp molecule (template) through polymerization or phase inversion. This study focuses on the application of both methods in the realization of polymeric membranes with selective recognition and adsorption properties. Imprinted polymethacrylic acid (PMAA) particles, exhibiting specific binding sites for cholesterol molecule (template), were realized via precipitation polymerization in the shape of nanobeads and loaded in the bulk or on the surface of methylmethacrylate-acrylic acid P(MMA-co-AA) membranes obtained by the non-solvent induced phase separation (NIPS) technique. In this way, specific cavities were introduced into the membrane network to enhance and specialize uptake performances of the porous membranes taking advantage of the particle characteristics. Rebinding performances towards cholesterol in a physiological environment were tested showing very interesting results: the adsorption of cholesterol molecules from physiological solution was increased by using composite membrane-nanobead systems instead of control membranes (a quantitative increase of 14 mg of cholesterol per g of polymer matrix in respect of blank membrane was detected). The results obtained showed an improved performance of composite membranes, but also an unmodified behavior of loaded nanobeads (with respect to free ones) concerning the recognition capability in aqueous medium, which is the most difficult obstacle to overcome in molecular imprinting. The absolute rebinding capacity and the imprinting efficiency of membranes were in the range (and in some case higher) of other efficient systems, but the real improvement was that molecularly imprinted embranes showed an excellent recognition capacity in physiological medium instead of organic solvents

  4. Oxide coatings on flexible substrates for electrochromic applications

    One of the most studied classes of materials in the modern microelectronic devices are the metal oxides. There are different metal oxide films, such as electrodes, charge injecting and electrochromic coatings for displays or ''smart'' windows applications. This paper aims to describe the recent achievements for oxide coating deposition for flexible electrochromic displays. Although many deposition methods for production of such films have been developed, some of the achievements in the field of RF sputtering of transparent electrodes from indium-tin oxide on low-cost polyethyleneterephthalate substrate are presented. Attention is paid on some critical issues, such as films electro-optical parameters (sheet resistance, transparency in the visible range), adhesion, degradation due to stress and patterning ability

  5. Method of forming oxide coatings. [for solar collector heating panels

    Mcdonald, G. E. (Inventor)

    1983-01-01

    This invention is concerned with an improved plating process for covering a substrate with a black metal oxide film. The invention is particularly directed to making a heating panel for a solar collector. A compound is electrodeposited from an aqueous solution containing cobalt metal salts onto a metal substrate. This compound is converted during plating into a black, highly absorbing oxide coating which contains hydrated oxides. This is achieved by the inclusion of an oxidizing agent in the plating bath. The inclusion of an oxidizing agent in the plating bath is contrary to standard electroplating practice. The hydrated oxides are converted to oxides by treatment in a hot bath, such as boiling water. An oxidizing agent may be added to the hot liquid treating bath.

  6. Composition of Organic Compounds Adsorbed on PM10 in the Air Above Maribor.

    Miuc, Alen; Vončina, Ernest; Lečnik, Uroš

    2015-01-01

    Organic compounds in atmospheric particulate matterabove Maribor were analysed in 120 samples of PM10 sampled according to the EN 12341:2014 reference method. Organic compounds compositions were investigated together with the primary and secondary sources of air pollution. Silylation as derivatisation method was used for the GC/MS determination of volatile and semi-volatile polar organic compounds. Distribution of fatty acids, n-alkanes and iso-alkanes, phthalate esters, siloxanes, different sterols, various sugars and sugar alcohols, compounds of lignin and resin acids, dicarboxylic acids from photochemical reactions, PAHs, organic nitrogen compounds and products from secondary oxidation of monoterpenes were determined. The use of silicone grease for the purpose of lubricating the impact surface of the air sampler caused higher values of gravimetric determination. Solid particles may have been bounced from the surface of a greasy impact plate and re-entrained within the air stream and then collected on a sample filter. The carryover of siloxanes was at least from 5% up to 15% of the accumulated particles weight, depending on ambient temperature. This was the reason that the gravimetric results for determination of PM10 according to the standard EN 12341:2014 were overestimated. PMID:26680711

  7. Laccase Immobilized on a PAN/Adsorbents Composite Nanofibrous Membrane for Catechol Treatment by a Biocatalysis/Adsorption Process

    Qingqing Wang

    2014-03-01

    Full Text Available The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ± 2.23% chemical oxygen demand (COD removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO can be combined together for catechol treatment in industrial applications.

  8. Nanoscaled zero valent iron/graphene composite as an efficient adsorbent for Co(II) removal from aqueous solution.

    Xing, Min; Wang, Jianlong

    2016-07-15

    A magnetic graphene, i.e., nanoscaled zero valent iron/graphene (0FG) composite, was prepared, characterized and applied for the removal of Co(II) from aqueous solution. The magnetic graphene (0FG) was synthesized through reduction of graphene oxide (GO) and ferrous ions by potassium borohydride. The kinetics and isotherms of Co(II) adsorption onto 0FG were investigated. The mechanism for Co(II) removal was proposed based on the Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the X-ray absorption fine structure (XAFS) analysis. The results showed that pseudo second-order models and the Freundlich isotherm model fitted well with the data obtained. The adsorption capacity of 0FG was calculated from the Langmuir isotherm, which was 65.58, 101.60 and 134.27mg/g at 10, 20 and 30°C, respectively. Thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Co(2+) was stabilized by γ-FeOOH/γ-Fe2O3/Fe3O4 on the surface of graphene sheets, forming CoFe2O4-like nanocrystals. The coordination numbers and interatomic distances indicated that Co(2+) mainly occupied the octahedral site, while pseudo-tetrahedral coordination may occur by dehydroxylation of Co(O,OH)6. Magnetic graphene is a potential adsorbent for Co(2+) removal. PMID:27115333

  9. Preparation and Characterization of a Carbon/Fly Ash Composite Adsorbent%C/粉煤灰复合吸附材料的制备及表征

    张德懿; 马颖; 王毅; 冯辉霞; 雒和明; 满新伟; 郝远

    2011-01-01

    以粉煤灰和蔗糖为原料,浓硫酸为炭化剂,制备了一种新型的C/粉煤灰复合吸附材料.采用X光电子能谱、红外吸收光谱、场发射扫描电子显微镜、X射线衍射及N2气吸附实验对所制备复合材料进行了表征.结果表明,粉煤灰表面被类石墨态炭纳米颗粒所包裹,复合材料表面密集分布着大量的介孔,Brunauer-Emmett-Teller(BET)比表面积SBET =5.4 m2/g,并且在该复合材料表面含有丰富的-SO3H、-COOH和-OH等含氧官能团.考察了所制备的复合材料对典型阳离子型染料亚甲基蓝及重金属离子的吸附能力,结果表明,该复合材料具有优异的吸附性能,其对亚甲基蓝的吸附能力达到活性炭的83.7%,对典型重金属离子的吸附能力优于市售活性炭.所制备复合材料可作为活性炭的一种替代品,用于水中有机染料和重金属离子的吸附处理.%Fly ash, a kind of industrial solid waste material produced during the combustion of coal in the electricity generation, was utilized to prepare a novel carbon/fly ash composite adsorbent with core-shell structures by a partial carbonization and sulfonation process. The prepared composite adsorbent was characterized with XPS, FT-IR, SEM, XRD and gas adsorption experiments. The results showed that fly ash was coated by graphite-like carbon nanoparticles. The carbon, oxygen, silica and sulfur are the main elements on the surface of the prepared composite adsorbent. Among them, the carbon and oxygen elements are the dominant superficial elements. An abundant of mesopores existed on the surface of the composite adsorbent. The Brunauer Emmett Teller ( BET) surface area SBET is 5.4 mVg. Meanwhile, an abundant of oxygen functional groups, such as carboxyl, hydroxyl and sulfonic groups, which were very effective in capturing cationic organic dyes and heavy metal ions and acted as the main adsorption sites of the composite adsorbent, were successfully introduced on the composite

  10. EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism

    Hasannejad, H. [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shahrabi, T., E-mail: Tshahrabi34@modares.ac.ir [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Jafarian, M. [Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of); Rouhaghdam, A. Sabour [Department of Materials Science and Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2011-02-03

    Research highlights: > In this study a new procedure was used for electrodeposition of Ni-cerium oxide amorphous-nano crystalline composite coatings. The innovation of this method is that the metal and oxides are deposited simultaneously on the samples from the plating bath solution containing Ni ions and Ce ions with no powder added. - Abstract: In this study a novel procedure was used for the electrodeposition of Ni-cerium oxide nano crystalline composite coatings. The novelty of this method lies in the fact that the metal and the oxide are both deposited simultaneously on the substrate, directly from the plating bath containing Ni and Ce ions with no oxide powder addition. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to study the mechanisms of Ni-CeO{sub 2} nanocomposite coating deposition. The results indicated that the morphology of Ni-cerium oxide coatings varied based on the Ni:Ce ion ratio. When this ratio exceeds 100, sporadic distribution of cerium oxide in the Ni matrix occurred. On the other hand, when the aforementioned ratio was less than 100, it was found that Ni species were dispersed in a continuous film of cerium oxide. Furthermore, it was observed that Ni in Ni-cerium oxide composite coating was nanocrystalline, while cerium oxide was amorphous. Introduction of the cerium ions to the plating bath resulted in the reduction of the Ni grains average size.

  11. EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism

    Research highlights: → In this study a new procedure was used for electrodeposition of Ni-cerium oxide amorphous-nano crystalline composite coatings. The innovation of this method is that the metal and oxides are deposited simultaneously on the samples from the plating bath solution containing Ni ions and Ce ions with no powder added. - Abstract: In this study a novel procedure was used for the electrodeposition of Ni-cerium oxide nano crystalline composite coatings. The novelty of this method lies in the fact that the metal and the oxide are both deposited simultaneously on the substrate, directly from the plating bath containing Ni and Ce ions with no oxide powder addition. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) were used to study the mechanisms of Ni-CeO2 nanocomposite coating deposition. The results indicated that the morphology of Ni-cerium oxide coatings varied based on the Ni:Ce ion ratio. When this ratio exceeds 100, sporadic distribution of cerium oxide in the Ni matrix occurred. On the other hand, when the aforementioned ratio was less than 100, it was found that Ni species were dispersed in a continuous film of cerium oxide. Furthermore, it was observed that Ni in Ni-cerium oxide composite coating was nanocrystalline, while cerium oxide was amorphous. Introduction of the cerium ions to the plating bath resulted in the reduction of the Ni grains average size.

  12. Nanocellulose/nanobentonite composite anchored with multi-carboxyl functional groups as an adsorbent for the effective removal of Cobalt(II) from nuclear industry wastewater samples.

    Anirudhan, T S; Deepa, J R; Christa, J

    2016-04-01

    A novel adsorbent, poly(itaconic acid/methacrylic acid)-grafted-nanocellulose/nanobentonite composite [P(IA/MAA)-g-NC/NB] with multi carboxyl functional groups for the effective removal of Cobalt(II) [Co(II)] from aqueous solutions. The adsorbent was characterized using FTIR, XRD, SEM-EDS, AFM and potentiometric titrations before and after adsorption of Co(II) ions. FTIR spectra revealed that Co(II) adsorption on to the polymer may be due to the involvement of COOH groups. The surface morphological changes were observed by the SEM images. The pH was optimized as 6.0. An adsorbent dose of 2.0g/L found to be sufficient for the complete removal of Co(II) from 100mg/L at room temperature. Pseudo-first-order and pseudo-second-order models were tested to describe kinetic data and adsorption of Co(II) follows pseudo-second-order model. The equilibrium attained at 120min. Isotherm studies were conducted and data were analyzed using Langmuir, Freundlich and Sips isotherm models and best fit was Sips model. Thermodynamic study confirmed endothermic and physical nature of adsorption of the Co(II) onto the adsorbent. Desorption experiments were done with 0.1MHCl proved that without significant loss in performance adsorbent could be reused for six cycles. The practical efficacy and effectiveness of the adsorbent were tested using nuclear industrial wastewater. A double stage batch adsorption system was designed from the adsorption isotherm data of Co(II) by constructing operating lines. PMID:26844393

  13. XPS characterisation of plasma treated and zinc oxide coated PET

    At first, X-ray photoelectron spectroscopy (XPS) analyses of reference and carbon dioxide plasma treated polyethylene terephthalate (PET) were carried out. Significant chemical modifications were outlined in the treated PET surface in comparison with the reference one. The formation of new oxygenated groups was evidenced. These modifications heighten the level of interactions between the polymer substrate and the deposited coating. In a second stage, zinc oxide thin films were elaborated by r.f. magnetron sputtering from a ceramic target and with a reactive gas (mixture of argon-1% oxygen) under optimised conditions on CO2 plasma treated PET. The interfacial chemistry between the plasma treated PET and the zinc oxide was also studied by XPS. The line shape changes in the high-resolution core level spectra of carbon C1s, oxygen O1s, and zinc (Zn2p3/2, Zn3p), with the progressive deposition of zinc oxide coatings being recorded. The obtained spectra were fitted to mixed Gaussian-Lorentzian components using XPS CASA software. An interaction scheme between the zinc oxide thin layer and its polymer substrate, in the first stage of deposition, was proposed and checked by corroborating the findings of the different XPS spectra and their decompositions. It suggests the formation of Zn-O-C complexes at the interface, which are promoted by an electron transfer from zinc to oxygen in oxygenated species, mainly alcohol groups, generated by the CO2 plasma treatment of PET.

  14. Novel transparent conducting sol-gel oxide coatings

    This work focuses on the preparation of novel ternary transparent conducting oxide coatings on glass by the sol-gel method. The coatings were deposited by spin-coating from solutions of appropriate metal precursors and heat-treated at different heat-treatment procedures. An increase in electrical conductivity was achieved by a final forming gas treatment. Best electrical and optical properties have been obtained for coatings of crystalline Zn2SnO4, Zn3In2O6 and Zn5In2O8 and X-ray amorphous ZnSnO3 with resistivities in the order of 10-2-10-1 Ω cm, an average transmission in the visible of 85% and an average surface roughness of ∼ 1 nm. ZnGa2O4 and GaSbO4 coatings showed no electrical conductivity. For Zn2SnO4 coatings, a restricted crystallite growth was observed probably due to phase segregation effects. Electrical properties of coatings in the system ZnO-In2O3 were interpreted on the basis of the percolation theory

  15. Adsorption kinetics for the removal of soluble manganese by oxide- coated filter media

    Hungate, Robert W.

    1988-01-01

    This study was conducted to examine the kinetics of manganese sorption on oxide-coated filter media. Initial experimentation confirmed the findings of other investigators, the Mn2+ sorption capacity of oxide-coated media increases as solution pH increases. Further study revealed that uptake rate kinetics could be described by first order kinetics and also increased with increasing solution pH. The addition of free chlorine (HOCl) to solution greatly enhanced Mn2+ uptak...

  16. Corrosion evaluation of zirconium doped oxide coatings on aluminum formed by plasma electrolytic oxidation.

    Bajat, Jelena; Mišković-Stanković, Vesna; Vasilić, Rastko; Stojadinović, Stevan

    2014-01-01

    The plasma electrolytic oxidation (PEO) of aluminum in sodium tungstate (Na(2)WO(4) · (2)H(2)O) and Na(2)WO(4) · (2)H(2)O doped with Zr was analyzed in order to obtain oxide coatings with improved corrosion resistance. The influence of current density in PEO process and anodization time was investigated, as well as the influence of Zr, with the aim to find out how they affect the chemical content, morphology, surface roughness, and corrosion stability of oxide coatings. It was shown that the presence of Zr increases the corrosion stability of oxide coatings for all investigated PEO times. Evolution of EIS spectra during the exposure to 3% NaCl, as a strong corrosive agent, indicated the highest corrosion stability for PEO coating formed on aluminum at 70 mA/cm(2) for 2 min in a zirconium containing electrolyte. PMID:25125114

  17. Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability

    Velmurugan Thavasi

    2009-01-01

    Full Text Available We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness.

  18. Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability

    Lala, Neeta L.; Thavasi, Velmurugan; Ramakrishna, Seeram

    2009-01-01

    We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness. PMID:22389589

  19. Evaluating the performance of modified adsorbent of zero valent iron nanoparticles – Chitosan composite for arsenate removal from aqueous solutions

    K Yaghmaeian

    2016-03-01

    Full Text Available Background and Objective: Arsenic is one of the most toxic pollutants in groundwater and surface water. Arsenic could have lots of adverse impacts on human health. Therefore, access to new technologies is required to achieve the arsenic standard. Materials and Methods: The present study was conducted at laboratory scale in non-continuous batches. The adsorbent of zero-valent iron nanoparticles -Chitosan was produced through reducing ferric iron by sodium borohydride (NaBH4 in the presence of chitosan as a stabilizer. At first, the effect of various parameters such as contact time (5-120 min, pH (3-10, adsorbent dose (0.3-3.5 g/L and initial concentration of arsenate (2-10 mg/L were investigated on process efficiency. Then optimum conditions in terms of contact time, pH, adsorbent dose and initial concentration of arsenate were determined by RSM method. Freundlich and Langmuir isotherm model equilibrium constant, pseudo-first and second order kinetic constants were calculated. The residual arsenate was measured y using ICP-AES. Results: The optimum values based on RSM for pH, absorbent dose, contact time, and initial concentration of arsenate were 7.16, 3.04 g/L, 91.48 min, and 9.71 mg/L respectively. Langmuir isotherm with R2= 0.9904 for Arsenate was the best graph for the experimental data. According to Langmuir isotherm model, the maximum amount of arsenate adsorption was 135.14mg/g. . The investigation of arsenate adsorption kinetics showed that arsenate adsorption follows the pseudo-second kinetics model. Conclusion: This research showed that the adsorption process is depended on pH. With increasing pH, the ability of amine groups in chitosan are decreased to protonation, caused to decrease the efficiency of arsenate removal at high pH.

  20. Scandium oxide coated polycrystalline tungsten studied using emission microscopy and photoelectron spectroscopy

    Thermionic electron emission from 200 to 500 nm thick coatings of scandium oxide on tungsten foil have been examined in thermionic emission microscopy, spectroscopic photoelectron microcopy, synchrotron radiation and ultraviolet photoelectron spectroscopy (UPS). A clear dependence of the scandium oxide-W electron yield on the grain orientation of the polycrystalline tungsten is observed in thermionic emission and photoelectron emission. -- Highlights: ► Polycrystalline tungsten imaged with spectroscopic thermionic emission microcopy. ► Scandium oxide coated tungsten grains observed during thermionic emission. ► Direct visualization of the surface electron yield due to oxide coatings. ► Findings related to thermionic cathodes.

  1. Synthesis and electrochemical characterization of porous niobium oxide coated 316L SS for orthopedic applications

    Niobium oxide was prepared using sol-gel process and coated on 316L stainless steel (SS) substrate via dip-coating technique. The surface characterization results after a thermal treatment revealed that the coated surface was porous, uniform and well crystalline on the substrate. The corrosion resistance and bioactivity of the porous niobium oxide coated 316L SS in simulated body fluid (SBF) solution was evaluated. The in vitro test revealed a layer of carbonate-containing apatite formation over the coated porous surface. The results indicated that the porous niobium oxide coated 316L SS exhibited a high corrosion resistance and an enhanced biocompatibility in SBF solution.

  2. Quantifying the influence of humic acid adsorption on colloidal microsphere deposition onto iron-oxide-coated sand

    This article describes an approach for quantifying microsphere deposition onto iron-oxide-coated sand under the influence of adsorbed Suwannee River Humic Acid (SRHA). The experimental technique involved a triple pulse injection of model latex microspheres (microspheres) in pulses of (1) microspheres, followed by (2) SRHA, and then (3) microspheres, into a column filled with iron-coated quartz sand as a water-saturated porous medium. A random sequential adsorption model (RSA) simulated the gradual rise in the first (microsphere) breakthrough curve (BTC). Using the same model calibration parameters a dramatic increase in concentration at the start of the second particle BTC, generated after SRHA injection, could be simulated by matching microsphere concentrations to extrapolated RSA output. RSA results and microsphere/SRHA recoveries showed that 1 μg of SRHA could block 5.90 ± 0.14 x 109 microsphere deposition sites. This figure was consistent between experiments injecting different SRHA masses, despite contrasting microsphere deposition/release regimes generating the second microsphere BTC. - This paper describes a method to quantify the influence of humic acid adsorption on particulate colloid deposition in saturated porous media.

  3. Zero-valent iron and iron oxide-coated sand as a combination for removal of co-present chromate and arsenate from groundwater with humic acid

    The combination of zero-valent iron (Fe0) and iron oxide-coated sand (IOCS) was used to remove Cr(VI) and As(V) from groundwater in this study. The efficiency and the removal mechanism of Cr(VI) and As(V) by using this combination, with the influence of humic acid (HA), were investigated using batch experiments. Results showed that, compared to using Fe0 or IOCS alone, the Fe0-IOCS can perform better on the removal of both Cr(VI) and As(V). Metal extraction studies showed that As(V) was mainly removed by IOCS and iron corrosion products while Cr(VI) was mainly removed by Fe0 and its corrosion products. Competition was found between Cr(VI) and As(V) for the adsorption sites on the iron corrosion products. HA had shown insignificant effects on Cr(VI) removal but some effects on As(V) removal kinetics. As(V) was adsorbed on IOCS at the earlier stage, but adsorbed/coprecipitated with the iron corrosion products at the later stage. - Research Highlights: → Fe0-IOCS is better reactive media for removing Cr(VI) and As(V) from groundwater. → As(V) was mainly removed by the IOCS and the iron corrosion products. → Cr(VI) was mainly removed by Fe0 and its corrosion products. → As(V) adsorption was inhibited in the presence of HA, when using Fe0 alone. → IOCS can provide the adsorption sites for As(V) that complement the weakness of Fe0. - Chromate and arsenate-contaminated groundwater can be better treated by using combination of zero-valent iron and iron oxide-coated sand.

  4. Adsorption of drinking water fluoride on a micron-sized magnetic Fe3O4@Fe-Ti composite adsorbent

    Zhang, Chang; Li, Yingzhen; Wang, Ting-Jie; Jiang, Yanping; Wang, Haifeng

    2016-02-01

    A micron-sized magnetic adsorbent (MMA) for fluoride removal from drinking water was prepared by spray drying and subsequent calcination of a magnetic Fe3O4@Fe-Ti core-shell nanoparticle slurry. The MMA granules had high mechanical strength and stability against water scouring, can be easily separated from the water by a magnet, and had a high selectivity for fluoride versus common co-existing ions and high fluoride removal efficiency in a wide range of initial pH of 3-11. Abundant hydroxyl groups on the MMA surface acted as the active sites for fluoride adsorption, which resulted in a high affinity of the MMA for fluoride. The pH in the adsorption process affected the adsorption significantly. At neutral initial pH, the adsorption isotherm was well fitted with the Langmuir model, and the maximum adsorption capacity reached a high value of 41.8 mg/g. At a constant pH of 3, multilayer adsorption of fluoride occurred due to the abundant positive surface charges on the MMA, and the adsorption isotherm was well fitted with the Freundlich model. The MMA had a fast adsorption rate, and adsorption equilibrium was achieved within 2 min. The adsorption kinetics followed a quasi-second order model. The regeneration of the MMA was easy and fast, and can be completed within 2 min. After 10 recycles, the fluoride removal efficiency of the MMA still remained high. These properties showed that the MMA is a promising adsorbent for fluoride removal.

  5. A New Adsorbent Composite Material Based on Metal Fiber Technology and Its Application in Adsorption Heat Exchangers

    Ursula Wittstadt

    2015-08-01

    Full Text Available In order to achieve process intensification for adsorption chillers and heat pumps, a new composite material was developed based on sintered aluminum fibers from a melt-extraction process and a dense layer of silico-aluminophosphate (SAPO-34 on the fiber surfaces. The SAPO-34 layer was obtained through a partial support transformation (PST process. Preparation of a composite sample is described and its characteristic pore size distribution and heat conductivity are presented. Water adsorption data obtained under conditions of a large pressure jump are given. In the next step, preparation of the composite was scaled up to larger samples which were fixed on a small adsorption heat exchanger. Adsorption measurements on this heat exchanger element that confirm the achieved process intensification are presented. The specific cooling power for the adsorption step per volume of composite is found to exceed 500 kW/m3 under specified conditions.

  6. Biogas from MSW landfill: Composition and determination of chlorine content with the AOX (adsorbable organically bound halogens) technique

    An exhaustive characterization of the biogas from some waste disposal facilities has been carried out. The analysis includes the main components (methane, carbon dioxide, nitrogen and oxygen) as well as trace components such as hydrogen sulphide, ammonia and VOCs (volatile organic compounds) including siloxanes and halogenated compounds. VOCs were measured by GC/MS (Gas Chromatography/Mass Spectrometry) using two different procedures: thermal desorption of the Tenax TA and Carbotrap 349 tubes and SPME (Solid Phase Micro-Extraction). A method has been established to measure the total halogen content of the biogas with the AOX (adsorbable organically bound halogens) technique. The equipment used to analyze the samples was a Total Organic Halogen Analyzer (TOX-100). Similar results were obtained when comparing the TOX (Total Organic Halogen) values with those obtained by GC/MS. The halogen content in all the samples was under 22 mg Cl/Nm3 which is below the limit of 150 mg/Nm3 proposed in the Spanish Regulations for any use of the biogas. The low chlorine content in the biogas studied, as well as the low content of other trace compounds, makes it suitable for use as a fuel for electricity generating engines

  7. Preparation and characterization of niobium oxide coated cellulose fiber

    Hydrous niobium(V) oxide has been investigated with respect to its surface acid strength, ion exchange capacity, and use as specific sorbent for many metal ions. The Nb2O5/cellulose composite was prepared by reacting α-cellulose with NbCl5-n (OC2H5)n, in nonaqueous solvent, under nitrogen atmosphere and submitting the obtained material to hydrolysis. An increase in the crystallinity degree is observed in the composite material because the precursor reagent reacts with the amorphous phase of the cellulose fibers. Loadings between 4.5 and 16.0% of the oxide were achieved and in every case the oxide particles uniformly cover the fiber surface. Lewis and Broensted acid sites were determined by using pyridine as the basic molecular probe

  8. Stoichiometry analysis of titanium oxide coating by LIBS

    Estupiñán, H.; Peña, D. Y.; García, Y. O.; Cabanzo, R.; Mejía-Ospino, E.

    2009-05-01

    In this work, laser induced breakdown spectroscopy (LIBS) is used to determine the composition of titanium oxide film produced by anodized of Ti6Al4V alloy. We have used Ti lines in the spectral region between 470-520 nm to determine temperature of the plasma generated on anodized surface of Ti6Al4V alloy for temperature determination by Boltzmann plot method. In order to measure the content of oxygen and titanium ratio on the surface the alloy, we have used the oxygen lines 777.194, 777.417 and 777.539 nm, and titanium lines 780.597 and 782.491 nm observed in an ambient of argon. Finally, we report the possibilities for the determination of the coating chemical composition using LIBS.

  9. Measurement of thermal conductivity of the oxide coating on autoclaved monel-400

    Thermal conductivity of the oxide coating on monel-400 has been measured by a direct method. The oxide coating is applied on an electrically conducting wire having stable characteristics. The wire is placed in a constant temperature bath and a constant direct current is passed through it. The wire gets heated and loses heat to the surrounding. Temperature is measured by considering it as a resistance thermometer. A convection heat transfer coefficient, which is difficult to measure experimentally but is involved in the analytical expression for thermal conductivity, is eliminated by connecting a second uncoated wire of a noble metal having similar surface finish as that of the coated wire in series with it. The accuracy of the method is nearly six percent. However, the method is not easily applicable for very thin (thickness <= 1μ), highly porous coatings and materials having relatively large thermal conductivity. (M.G.B.)

  10. A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

    Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

    2015-03-01

    Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

  11. Corrosion properties of plasma electrolytic oxidation coatings on an aluminium alloy – The effect of the PEO process stage

    Dehnavi, Vahid, E-mail: vdehnavi@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, N6A 5B9 ON (Canada); Shoesmith, David W., E-mail: dwshoesm@uwo.ca [Surface Science Western, Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Luan, Ben Li, E-mail: Ben.Luan@nrc-cnrc.gc.ca [National Research Council Canada, 800 Collip Circle, London, N6G4X8 ON (Canada); Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Yari, Mehdi, E-mail: myari@uwo.ca [Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Liu, Xing Yang, E-mail: XingYang.Liu@nrc-cnrc.gc.ca [National Research Council Canada, 800 Collip Circle, London, N6G4X8 ON (Canada); Rohani, Sohrab, E-mail: srohani@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, N6A 5B9 ON (Canada)

    2015-07-01

    Plasma electrolytic oxidation (PEO) coatings were grown on an aluminium alloy substrate using different processing parameters which enabled samples to be coated to different stages of the PEO process. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques were employed to investigate the impedance properties of the resulting oxide coatings which will determine the corrosion performance of the coated alloy. Scanning electron microscopy was used to relate the morphology of the coatings with their corrosion performance. A direct relationship was found between the stage of the PEO process, which affects the microstructure of the coatings, and the corrosion performance. Coating thickness and phase composition did not have any measurable influence on coating corrosion performance. To some degree corrosion performance could be tailored by the processing parameters. - Highlights: • Corrosion performance of PEO coatings was found to be dependent on coating stage. • The PEO stage determined by the process parameters controlled coatings morphology. • Samples coated at the end of stage 3 demonstrated better corrosion properties. • Coating thickness and phase composition showed no influence on corrosion resistance.

  12. Corrosion properties of plasma electrolytic oxidation coatings on an aluminium alloy – The effect of the PEO process stage

    Plasma electrolytic oxidation (PEO) coatings were grown on an aluminium alloy substrate using different processing parameters which enabled samples to be coated to different stages of the PEO process. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques were employed to investigate the impedance properties of the resulting oxide coatings which will determine the corrosion performance of the coated alloy. Scanning electron microscopy was used to relate the morphology of the coatings with their corrosion performance. A direct relationship was found between the stage of the PEO process, which affects the microstructure of the coatings, and the corrosion performance. Coating thickness and phase composition did not have any measurable influence on coating corrosion performance. To some degree corrosion performance could be tailored by the processing parameters. - Highlights: • Corrosion performance of PEO coatings was found to be dependent on coating stage. • The PEO stage determined by the process parameters controlled coatings morphology. • Samples coated at the end of stage 3 demonstrated better corrosion properties. • Coating thickness and phase composition showed no influence on corrosion resistance

  13. Continuous adsorption of Pb(II) and methylene blue by engineered graphite oxide coated sand in fixed-bed column

    Gong, Ji-Lai, E-mail: jilaigong@gmail.com [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zhang, Yong-Liang; Jiang, Yan [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zeng, Guang-Ming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Cui, Zhi-Hui; Liu, Ke; Deng, Can-Hui; Niu, Qiu-Ya; Deng, Jiu-Hua [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Huan, Shuang-Yan [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2015-03-01

    Highlights: • GO-sand was prepared by coating GO on the surface of sand. • Pb(II) and MB were efficiently removed by GO-sand filter in column. • The removal of MB was enhanced with the presence of Pb(II). • GO-sand is low-cost and convenient for its application as packed bed filter. - Abstract: The mixture of several effluents, caused by the improper handling and management of effluents, generated multi-component wastewater containing both metals and dyes, leading to the complicated treatment process. In this study, a continuous adsorption of Pb(II) and methylene blue (MB) has been studied in single and binary solutions by using graphite oxide coated sand (GO-sand) as an adsorbent in a fixed-bed column. GO-sand was analyzed by X-ray photoelectron spectroscopy before and after analyte adsorption. Compared with sand filter, adsorption quantity and capacity for Pb(II) and MB by GO-sand filter were greatly increased. In Pb(II) and MB single solutions, the experimental parameters were investigated in detail including initial concentration, flow rate, bed depth and pH. Exhaustion time decreased with increasing initial concentration and flow rate, and increased with increasing bed depth and pH. In the Pb(II)-MB binary solution, exhaustion time significantly decreased for Pb(II) adsorption, but increased for MB adsorption. The reason was explained that the more favorable adsorption for MB onto the surface of GO-sand than that for Pb(II), which was derived from π–π interaction between MB and GO on sand surface in packed filter. The Yoon–Nelson model was applied at different concentration of Pb(II) and MB to predict the breakthrough curves. The experimental data were well fit with the model indicating that it was suitable for this column design.

  14. Continuous adsorption of Pb(II) and methylene blue by engineered graphite oxide coated sand in fixed-bed column

    Highlights: • GO-sand was prepared by coating GO on the surface of sand. • Pb(II) and MB were efficiently removed by GO-sand filter in column. • The removal of MB was enhanced with the presence of Pb(II). • GO-sand is low-cost and convenient for its application as packed bed filter. - Abstract: The mixture of several effluents, caused by the improper handling and management of effluents, generated multi-component wastewater containing both metals and dyes, leading to the complicated treatment process. In this study, a continuous adsorption of Pb(II) and methylene blue (MB) has been studied in single and binary solutions by using graphite oxide coated sand (GO-sand) as an adsorbent in a fixed-bed column. GO-sand was analyzed by X-ray photoelectron spectroscopy before and after analyte adsorption. Compared with sand filter, adsorption quantity and capacity for Pb(II) and MB by GO-sand filter were greatly increased. In Pb(II) and MB single solutions, the experimental parameters were investigated in detail including initial concentration, flow rate, bed depth and pH. Exhaustion time decreased with increasing initial concentration and flow rate, and increased with increasing bed depth and pH. In the Pb(II)-MB binary solution, exhaustion time significantly decreased for Pb(II) adsorption, but increased for MB adsorption. The reason was explained that the more favorable adsorption for MB onto the surface of GO-sand than that for Pb(II), which was derived from π–π interaction between MB and GO on sand surface in packed filter. The Yoon–Nelson model was applied at different concentration of Pb(II) and MB to predict the breakthrough curves. The experimental data were well fit with the model indicating that it was suitable for this column design

  15. Radium, thorium, and actinium extraction from seawater using an improved manganese-oxide-coated fiber

    Laboratory experiments were conducted to determine the efficiency with which improved manganese-oxide-coated acrylic fibers extract radium, thorium, and actinium from seawater. Tests were made using surface seawater spiked with 227Ac, 227Th and 223Ra. For sample volumes of approximately 30 liters and flow rates up to 0.5 liters per minute, radium and actinium are removed quantitatively. Approximately 80-95% of the thorium is removed under these same conditions. (Auth.)

  16. Characteristics of element composition of aerosols adsorbed on leaves by radioactivation analysis and their effects on plants

    Takamatsu, Takejiro; Koshikawa, Masami [National Inst. for Environmental Studies, Tsukuba, Ibaraki (Japan); Sase, Hiroyuki; Masuzawa, Toshiyuki; Kawashima, Munetsugu; Takada, Jitsuya; Matsushita, Rokuji

    1999-01-01

    Aerosol deposits on leaves of various trees, especially cedar in different regions of Japan were collected to characterize the elemental composition using neutron activation analysis, ICP-AES, etc. and also investigate the effects of deposit aerosols on plants and the efficacy as an indicator for air pollution. Compared with the elemental composition of the soil, Se, Cr, Au, Br, As, Sb, Ag, etc. were more abundant in aerosols on cedar leaves. Especially, Sb is thought to be mostly derived from combustion of fossil fuels (exhaust gas from cars, etc.). Since Sb was accumulated on leaves at high levels and the analytical precision for Sb by neutron radioactivation was very high, the element was thought useful as an indicator for air pollution. If the amounts of Sb on the leaves of cedar and pine trees, which are widely distributed in Japan are determined, the degrees of pollution in all regions of Japan would be determined. In cedar trees of Saitama Prefecture where the deposit amounts of aerosols were comparatively larger, 42% of stoma was covered with the deposits, resulting that the rate of cuticular transpiration was increased and the amounts of basic elements leached from the leave surface was also increased. Thus, it was suggested that these changes might be the cause of recent declining of cedars in Japanese urban regions. (M.N.)

  17. Characteristics of element composition of aerosols adsorbed on leaves by radioactivation analysis and their effects on plants

    Aerosol deposits on leaves of various trees, especially cedar in different regions of Japan were collected to characterize the elemental composition using neutron activation analysis, ICP-AES, etc. and also investigate the effects of deposit aerosols on plants and the efficacy as an indicator for air pollution. Compared with the elemental composition of the soil, Se, Cr, Au, Br, As, Sb, Ag, etc. were more abundant in aerosols on cedar leaves. Especially, Sb is thought to be mostly derived from combustion of fossil fuels (exhaust gas from cars, etc.). Since Sb was accumulated on leaves at high levels and the analytical precision for Sb by neutron radioactivation was very high, the element was thought useful as an indicator for air pollution. If the amounts of Sb on the leaves of cedar and pine trees, which are widely distributed in Japan are determined, the degrees of pollution in all regions of Japan would be determined. In cedar trees of Saitama Prefecture where the deposit amounts of aerosols were comparatively larger, 42% of stoma was covered with the deposits, resulting that the rate of cuticular transpiration was increased and the amounts of basic elements leached from the leave surface was also increased. Thus, it was suggested that these changes might be the cause of recent declining of cedars in Japanese urban regions. (M.N.)

  18. One-Step Fabrication of Microchannels Lined with a Metal Oxide Coating.

    Patil, Sandip; Ranjan, Amit; Maitra, Tanmoy; Sharma, Ashutosh

    2016-04-27

    We demonstrate a simple, single-step method for metal/metal oxide coating on interior walls of microchannels in an elastomeric material like PDMS, which is the mainstay of microfluidic devices. The fabrication process involves electrodeposition of cuprous oxide on a metallic wire or a sheet, embedding it inside a PDMS matrix along with the cross-linker, curing and then swelling the PDMS elastomer, and finally pulling out the template metal wire or the metal sheet from the PDMS matrix. Stronger attachment of the metal oxide layer to PDMS allows the transfer of the metal oxide coating originally present on the template surface (wire or sheet) to the channel wall resulting in a microchannel/microslit lined with the metal/metal oxide layer. In view of the catalytic activity associated with transition metal oxides, this simple method offers a cost-effective and versatile technique to fabricate microfluidic and lab-on-a-chip devices which can be utilized as microcatalytic reactors or chemical filters. As a proof of concept, we have successfully tested the metal oxide coated microchannels and microslits as active sites for adsorption of iodide ions. PMID:27035524

  19. Cavitation erosion resistance of microarc oxidation coating on aluminium alloy

    Cheng, Feng [School of Mechanical Engineering, Southeast University, Nanjing, 211189 (China); Jiang, Shuyun, E-mail: jiangshy@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing, 211189 (China); Liang, Jun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2013-09-01

    Two ceramic coatings are prepared on 2124 aluminum alloy by microarc oxidation (MAO) technology. To explore the cavitation erosion resistance of the MAO coating, cavitation tests were performed by using a rotating-disk test rig. The mass losses, surface morphologies, chemical compositions and the phase constituents of the samples after cavitation tests were examined by using digital balance, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results indicate that the MAO coatings can extend the incubation period of aluminum alloy, and thus enhance the cavitation erosion resistance as compared to the untreated aluminum alloy samples. After duration of 63 h cavitation test, a lot of erosion pits and the particles in various shapes can be observed on the surfaces of the aluminum alloy samples, while only a few erosion pits are observed on the MAO coatings. Moreover, the mean depths of erosion on the MAO coatings are lower in the first 30 h and are independent on erosion time. The results show that the cavitation erosion of MAO coating is governed by water mechanical impaction, resulting from the effects of brittle fracture of the MAO coating.

  20. Micro-arc oxidation coatings on Mg-Li alloys

    XU Yongjun; LI Kang; YAO Zhongping; JIANG Zhaohua; ZHANG Milin

    2009-01-01

    Micro-arc oxidation (MAO) method was used for the surface modification of an Mg-5wt.%Li alloy. Ceramic coatings were in-situ fabricated on the Mg-Li alloy. The morphology feature, phase composition, and corrosion-resistance of the formed ceramic coatings were studied by SEM, XRD, and electrochemical methods, respectively. The results showed that the coatings produced in a sodium silicate solution system were composed of MgO and Mg2SiO4. The ceramic coating became thicker and the content of Mg2SiO4 phase increased as the concentration of Na2SiO3 increased in the solution. The coating was loose at the low concentration of Na2SiO3 and was compact at the high concentration of Na2SiO3. The coated samples had a better corrosion resistance than the Mg-Li substrate in terms of the Tafel polarization curves and the cyclic voltammetry curves (CV).

  1. Peroxide induced tin oxide coating of graphene oxide at room temperature and its application for lithium ion batteries

    We describe a new, simple and low-temperature method for ultra-thin coating of graphene oxide (GO) by peroxostannate, tin oxide or a mixture of tin and tin oxide crystallites by different treatments. The technique is environmentally friendly and does not require complicated infrastructure, an autoclave or a microwave. The supported peroxostannate phase is partially converted after drying to crystalline tin oxide with average, 2.5 nm cassiterite crystals. Mild heat treatment yielded full coverage of the reduced graphene oxide by crystalline tin oxide. Extensive heat treatment in vacuum at >500  °C yielded a mixture of elemental tin and cassiterite tin oxide nanoparticles supported on reduced graphene oxide (rGO). The usefulness of the new approach was demonstrated by the preparation of two types of lithium ion anodes: tin oxide–rGO and a mixture of tin oxide and tin coated rGO composites (SnO2–Sn–rGO). The electrodes exhibited stable charge/discharge cyclability and high charging capacity due to the intimate contact between the conductive graphene and the very small tin oxide crystallites. The charging/discharging capacity of the anodes exceeded the theoretical capacity predicted based on tin lithiation. The tin oxide coated rGO exhibited higher charging capacity but somewhat lower stability upon extended charge/discharge cycling compared to SnO2–Sn–rGO. (paper)

  2. Investigation of rare earth sealing of porous micro-arc oxidation coating formed on AZ91D magnesium alloy

    M.Laleh; Farzad Kargar; A.Sabour Rouhaghdam

    2012-01-01

    Magnesium and its alloys have been used in many industries,but they are reactive and require protection against aggressive environments.In this study,oxide coatings were applied on AZ91D magnesium alloy using micro-arc oxidation (MAO) process.Then,in order to seal the pores of the MAO coatings,the samples were immersed in cerium bath for different times.The surface morphologies and compositions of the coatings were analyzed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS),respectively.The corrosion behavior of the coatings was investigated with electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests in 3.5 wt.% NaCl solution.The amount of the porosity of the coating was measured by electrochemical method.It was found that the sealing treatments by immersion in cerium bath successfully sealed the pores of the MAO coatings.The results of the corrosion tests showed that the MAO coating which was sealed in Ce bath for 10 min enhanced the corrosion resistance of the substrate significantly.Furthermore,this coating had the lowest amount of the porosity among the coatings.

  3. Synthesis of linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(Ⅱ) from aqueous solutions

    Maryam Irani; Hanafi Ismail; Zulkifli Ahmad; Maohong Fan

    2015-01-01

    The purpose of this work is to remove Pb(Ⅱ) from the aqueous solution using a type of hydrogel composite.A hydrogel composite consisting of waste linear low density polyethylene,acrylic acid,starch,and organo-montmorillonite was prepared through emulsion polymerization method.Fourier transform infrared spectroscopy (FTIR),Solid carbon nuclear magnetic resonance spectroscopy (CNMR)),silicon-29 nuclear magnetic resonance spectroscopy (Si NMR)),and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite.The hydrogel composite was then employed as an adsorbent for the removal of Pb(Ⅱ) from the aqueous solution.The Pb(Ⅱ)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)),scanning electron microscopy (SEM)),and X-ray photoelectron spectroscopy ((XPS)).From XPS results,it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(Ⅱ).Kinetic studies indicated that the adsorption of Pb(Ⅱ)followed the pseudo-second-order equation.It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm.The maximum removal capacity of the hydrogel composite for Pb(Ⅱ) ions was 430 mg/g.Thus,the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(Ⅱ) adsorbent.

  4. Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm.

    Konwar, Achyut; Kalita, Sanjeeb; Kotoky, Jibon; Chowdhury, Devasish

    2016-08-17

    We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis

  5. Thermal Conductivity of Epoxy Resin Reinforced with Magnesium Oxide Coated Multiwalled Carbon Nanotubes

    Fei-Peng Du; Hao Tang; De-Yong Huang

    2013-01-01

    Magnesium oxide coated multiwalled carbon nanotubes (MgO@MWNT) were fabricated and dispersed into epoxy matrix. The microstructures of MgO@MWNT and epoxy/MgO@MWNT nanocomposites were characterized by TEM and SEM. Electrical resistivity and thermal conductivity of epoxy nanocomposites were investigated with high resistance meter and thermal conductivity meter, respectively. MgO@MWNT has core-shell structure with MgO as shell and nanotube as core, and the thickness of MgO shell is ca. 15 nm. Mg...

  6. Preparation and properties of poly(vinylidene fluoride nanocomposites blended with graphene oxide coated silica hybrids

    Q. Fu

    2012-04-01

    Full Text Available Graphene oxide coated silica hybirds (SiO2-GO were fabricated through electrostatic assembly in this work, then blended with poly(vinylidene fluoride (PVDF by solution mixing to make PVDF nanocomposites. The interfacial interaction was investigated by scanning electron microscopy (SEM, polarized optical microscopy (POM and Fourier transform infrared spectroscopy (FTIR. The results showed that the interfacial interaction was enhanced by adding of SiO2-GO and strong hydrogen bonds were observed. The as-made nanocomposites were investigated using standard tensile test and dynamic mechanical analysis (DMA measurements, mechanical properties of PVDF with SiO2-GO hybrids showed limited improvement.

  7. Photoluminescence blue shift of indium phosphide nanowire networks with aluminum oxide coating

    Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan J.; Oye, Michael M.; Kobayashi, Nobuhiko P. [Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, CA (United States); Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); NASA Ames Research Center, Moffett Field, CA (United States); Wei, Min [Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); School of Micro-Electronics and Solid-Electronics, University of Electronic Science and Technology of China, Chengdu (China)

    2014-07-15

    This paper describes our finding that optical properties of semiconductor nanowires were modified by depositing a thin layer of metal oxide. Indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst resulting in three-dimensional nanowire networks, and optical properties were obtained from the collective nanowire networks. The networks were coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. A continuous blue shift in photoluminescence spectra was observed when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from intrinsic negative fixed charges located at the inner oxide surface. Samples were further characterized by scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, and selective area diffractometry to better understand the physical mechanisms for the blue shift. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Anticorrosion properties of tin oxide coatings for carbonaceous bipolar plates of proton exchange membrane fuel cells

    Kinumoto, Taro; Nagano, Keita; Yamamoto, Yuji; Tsumura, Tomoki; Toyoda, Masahiro

    2014-03-01

    An anticorrosive surface treatment of a carbonaceous bipolar plate used in proton exchange membrane fuel cells (PEMFCs) was demonstrated by addition of a tin oxide surface coating by liquid phase deposition (LPD), and its effectiveness toward corrosion prevention was determined. The tin oxide coating was deposited by immersion in tin fluoride and boric acid solutions, without any observable decrease in the bipolar plate electrical conductivity. Anticorrosion properties of a flat carbonaceous bipolar plate were investigated in an aqueous HClO4 electrolyte solution (10 μmol dm-3) at 80 °C. CO2 release due to corrosion was significant for the bare specimen above 1.3 V, whereas no CO2 release was noted for the tin-oxide-coated specimen, even approaching 1.5 V. Moreover, minimal changes in contact angle against a water droplet before and after treatment indicated suppressed corrosion of the surface-coated specimen. Anticorrosion properties were also confirmed for a model bipolar plate having four gas flow channels. The tin oxide layer remained on the channel surfaces (inner walls, corners and intersections) after durability tests. Based on these results, tin-oxide-based surface coatings fabricated by LPD show promise as an anticorrosion technique for carbonaceous bipolar plates for PEMFCs.

  9. Tribological properties of solid lubricating film/microarc oxidation coating on Al alloys

    LUO Zhuang-zi; ZHANG Zhao-zhu; LIU Wei-min; TIAN Jun

    2005-01-01

    A process for preparation of solid lubricating films on micro-arc oxidation(MAO) coating was introduced to provide self-lubricating and wear-resistant multilayer coatings for aluminum alloys. The friction and wear behavior of various burnished and bonded solid lubricating films on the as-deposited and polished micro-arc oxidation coatings sliding against steel and ceramic counterparts was evaluated with a Timken tester and a reciprocating friction and wear tester, respectively. The burnished and bonded solid lubricating films on the polished micro-arc oxidation coatings are superior to the as-deposited ones in terms of the wear resistant behavior, because they lead to strengthened interfacial adhesion between the soft lubricating top-film and the hard polished MAO sub-coating, which helps increase the wear resistance of the solid lubricating film on multilayer coating. Thus the multilayer coatings are potential candidates as self-lubricating and wear-resistant coatings for Al alloy parts in engineering applications.

  10. Mn oxide coated catalytic membranes for a hybrid ozonation-membrane filtration: comparison of Ti, Fe and Mn oxide coated membranes for water quality.

    Byun, S; Davies, S H; Alpatova, A L; Corneal, L M; Baumann, M J; Tarabara, V V; Masten, S J

    2011-01-01

    In this study the performance of catalytic membranes in a hybrid ozonation-ceramic membrane filtration system was investigated. The catalytic membranes were produced by coating commercial ceramic ultrafiltration membranes with manganese or iron oxide nanoparticles using a layer-by-layer self-assembly technique. A commercial membrane with a titanium oxide filtration layer was also evaluated. The performance of the coated and uncoated membranes was evaluated using water from a borderline eutrophic lake. The permeate flux and removal of the organic matter was found to depend on the type of the metal oxide present on the membrane surface. The performance of the manganese oxide coated membrane was superior to that of the other membranes tested, showing the fastest recovery in permeate flux when ozone was applied and the greatest reduction in the total organic carbon (TOC) in the permeate. The removal of trihalomethanes (THMs) and haloacetic acids (HAAs) precursors using the membrane coated 20 times with manganese oxide nanoparticles was significantly better than that for the membranes coated with 30 or 40 times with manganese oxide nanoparticles or 40 times with iron oxide nanoparticles. PMID:20822791

  11. 淀粉/凹凸棒粘土复合吸附絮凝材料的研究%Study on Starch/Attapulgite Adsorbent and Flocculent Composite

    朱忠湛; 马喜君

    2015-01-01

    采用接枝聚合法在硅烷化凹凸棒粘土(OATP)表面接枝淀粉,制备淀粉/凹凸棒粘土(ATP)复合吸附絮凝材料.采用傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)对淀粉/ATP进行了表征,并对其制备条件进行了优化.结果表明,当淀粉质量分数(相对OATP质量)为100%,聚合反应时间为3 h,引发剂质量分数为0.003%,反应温度为60℃时,制备的淀粉/ATP对镉离子的最大吸附容量可达到36.78 mg/g.与ATP、OATP相比,淀粉/ATP对镉离子的吸附容量增大了2倍以上.复合材料具有比OATP更强的捕获能力,所形成的絮凝体大而密实,比淀粉絮凝剂具有更好的沉降性能.%Graft polymerization, starch/attapulgite( ATP) adsorbent was synthesized by grafting starch onto the silane coupling reagent modified ATP( OATP).The preparing conditions of the starch/ATP were investigated, and the analysis by FT/IR and SEM were conducted to characterize the synthesized starch/ATP.Fourier transform infrared spectroscopy( FT-IR) , scanning e-lectron microscopy( SEM) of starch/ATP were characterized and optimized its preparation conditions.The results show that the prepared starch/ATP gives a maximum Cd2+ adsorption capacity of 36.78 mg·g-1 under following conditions:starch mass con-centration of 100.0%( relative to OATP mass, the same hereinafter) , reaction time of 3 h, initiator dosage of 0.003%( weight) and reaction temperature of 60℃.It was found that the Cd2+ adsorption capacity of the Starch/ATP prepared under the above con-ditions is more than 2 folds compared with those of the ATP and OATP.The captured ability of the composite material is better than OATP, forming large and dense flocs, its settlement capacity is superior to starch flocculants.

  12. Influence of ionic strength and pH on the limitation of latex microsphere deposition sites on iron-oxide coated sand by humic acid

    Yang, X. [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, N. Ireland (United Kingdom); Flynn, R., E-mail: r.flynn@qub.ac.uk [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, N. Ireland (United Kingdom); Kammer, F. von der, E-mail: frank.von.der.kammer@univie.ac.at [Department of Environmental Geosciences, University of Vienna, Althanstrasse 14, 1090 Vienna (Austria); Hofmann, T. [Department of Environmental Geosciences, University of Vienna, Althanstrasse 14, 1090 Vienna (Austria)

    2011-07-15

    This study, for the first time, investigates and quantifies the influence of slight changes in solution pH and ionic strength (IS) on colloidal microsphere deposition site coverage by Suwannee River Humic Acid (SRHA) in a column matrix packed with saturated iron-oxide coated sand. Triple pulse experimental (TPE) results show adsorbed SRHA enhances microsphere mobility more at higher pH and lower IS and covers more sites than at higher IS and lower pH. Random sequential adsorption (RSA) modelling of experimental data suggests 1 {mu}g of adsorbed SRHA occupied 9.28 {+-} 0.03 x 10{sup 9} sites at pH7.6 and IS of 1.6 mMol but covered 2.75 {+-} 0.2 x 10{sup 9} sites at pH6.3 and IS of 20 mMol. Experimental responses are suspected to arise from molecular conformation changes whereby SRHA extends more at higher pH and lower ionic strength but is more compact at lower pH and higher IS. Results suggest effects of pH and IS on regulating SRHA conformation were additive. - Highlights: > We quantified the coupled role of pH and IS and humic acid on colloid deposition. > Humic acid enhances microsphere mobility more at higher pH and lower IS. > pH and IS may control the behaviour of humic acid by regulating its conformation. > The effect of pH and IS on regulating humic acid conformation is additive. - This paper quantifies the impact of pH and ionic strength on the transient deposition behaviour of colloids in porous medium in the presence of humic acid.

  13. Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

    Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

    2014-10-15

    Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.

  14. Influence of sodium silicate concentration on structural and tribological properties of microarc oxidation coatings on 2017A aluminum alloy substrate

    Polat, Aytekin, E-mail: apolat@nigde.edu.t [Department of Mechanical Engineering, Nigde University, Nigde 51100 (Turkey); Makaraci, Murat [Department of Mechanical Engineering, Kocaeli University, Kocaeli (Turkey); Usta, Metin [Department of Materials Science and Engineering, Gebze Institute of Technology, Kocaeli (Turkey)

    2010-08-20

    In this paper, thick and hard oxide coatings resistant to wear were produced on 2017A-T6 Al alloy by the microarc oxidation (MAO) technique in an alkali electrolyte consisting of different sodium silicate concentrations (0-8 g/l). The coatings were characterized by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometry. Microhardness, scratch adhesion and pin-on-disk sliding wear tests were also performed to evaluate the tribological properties of the coatings. The influence of sodium silicate concentration on the structural and tribological properties of the MAO coatings was discussed. Results reveal that increasing sodium silicate concentration from 0 to 8 g/l in the electrolyte caused an increase in the electrolyte conductivity (from 7.71 to 18.1 mS/cm) and a decrease in positive final voltage (from 627 to 590 V) in the MAO process. In response to the increase in sodium silicate concentration, the thickness, surface roughness (R{sub a}) and critical load (L{sub c}) corresponding to adhesive failure of the coatings were increased simultaneously from 74 to 144 {mu}m, and 4.4 to 6.58 {mu}m, and 127.76 to 198.54 N, respectively. At the same time, the phase structure and composition of the coatings also varied by the participation of silicate ions in the reactions and their incorporation into the coating structure. Moreover, it was observed that the coating formed in the low sodium silicate concentration (4 g/l) had higher surface hardness (2020 HV) and improved wear resistance than the one (1800 HV) formed in the high sodium silicate concentration (8 g/l). The coatings produced in three different electrolytic solutions provided an excellent wear resistance and a load carrying capacity compared to the uncoated aluminum alloy.

  15. Long-term corrosion inhibition mechanism of microarc oxidation coated AZ31 Mg alloys for biomedical applications

    Highlights: ► The corrosion behavior is significantly affected by the long-term immersion. ► The degradation is inhibited due to the corrosion product layer. ► The corrosion resistance is enhanced by optimized MAO electrolyte concentrations. ► The corrosion inhibition mechanism is presented by a Flash animation. - Abstract: This paper addresses the long-term corrosion behavior of microarc oxidation coated Mg alloys immersed in simulated body fluid for 28 days. The coatings on AZ31 Mg alloys were produced in the electrolyte of sodium phosphate (Na3PO4) at the concentration of 20 g/L, 30 g/L and 40 g/L, respectively. Scanning electron microscope (SEM) and optical micrograph were used to observe the microstructure of the samples before and after corrosion. The composition of the MAO coating and corrosion products were determined by X-Ray Diffraction (XRD). Corrosion product identification showed that hydroxyapatite (HA) was formed on the surface of the corroded samples. The ratio of Ca/P in HA determined by the X-ray Fluorescence (XRF) technique showed that HA is an acceptable biocompatible implant material. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion rate and the electrochemical impedance. The corrosion resistance of the coated Mg alloys can be enhanced by optimizing the electrolyte concentrations for fabricating samples, and is enhanced after immersing the coated samples in simulated body fluid for more than 14 days. The enhanced corrosion resistance after long-term immersion is attributed to a corrosion product layer formed on the sample surface. The inhibition mechanism of the corrosion process is discussed and presented with an animation

  16. Influence of the Structure of the Titanium Oxide Coating Surface on Immunocompetent Tumor Cells

    Khlusov, I. A.; Sharkeev, Yu. P.; Pichugin, V. F.; Legostaeva, E. V.; Litvinova, L. S.; Shupletsova, V. V.; Sokhonevich, N. A.; Khaziakhmatova, O. G.; Khlusova, M. Yu.; Gutor, S. S.; Tolkacheva, T. V.

    2016-03-01

    Results of a study of the properties of titanium oxide based coatings deposited on titanium substrates by microarc oxidation are presented that establish a relationship between physical and mechanical properties of the coating surface and their medical and biological properties. The required surface topography is formed by sandblasting of the substrate and is controlled by values of the roughness index Ra. A linear dependence of the amplitude of negative electrostatic potential of the oxide coating on the Ra value is established. The topography of the micro-arc coating surface determines its negative surface potential that apparently reduces the viability of the leukemia T cells of the Jurkat line via electrostatic and biological mechanisms unrelated to the generation of intracellular reactive oxygen species.

  17. Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter;

    2010-01-01

    tunability through synthetic chemistry. Phenylene-based molecules such as para-hexaphenylene (p6P) are of particular interest due to their ability to self-assemble into elongated, nanoscale, crystalline aggregates or ‘nanofibers’ [1]. Such nanofibers can emit polarized light with a highly anisotropic...... technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiOx [2] and Al2O3) were applied onto p6P nanofibers....... These treatments caused a reduction of the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings (P(TFE-PDD), and PMMA) do not interfere with the luminescence spectrum from the p6P but are not effective in stopping...

  18. Evaluation of the mechanical properties of microarc oxidation coatings and 2024 aluminium alloy substrate

    Xue Wen Bin; Deng Zhi Wei; Chen Ru Yi; Li Yong Liang; Zhang Ton Ghe

    2002-01-01

    A determination of the phase constituents of ceramic coatings produced on Al-Cu-Mg alloy by microarc discharge in alkaline solution was performed using x-ray diffraction. The profiles of the hardness, H, and elastic modulus, E, across the ceramic coating were determined by means of nanoindentation. In addition, a study of the influence of microarc oxidation coatings on the tensile properties of the aluminium alloy was also carried out. The results show that the H-and E-profiles are similar, and both of them exhibit a maximum value at the same depth of coating. The distribution of the alpha-Al sub 2 O sub 3 phase content determines the H- and E-profiles of the coatings. The tensile properties of 2024 aluminium alloy show less change after the alloy has undergone microarc discharge surface treatment.

  19. Evaluation of the mechanical properties of microarc oxidation coatings and 2024 aluminium alloy substrate

    Xue Wenbin [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Wang Chao [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Deng Zhiwei [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Chen Ruyi [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China); Li Yongliang [Analytical and Testing Centre, Beijing Normal University, Beijing, 100875 (China); Zhang Tonghe [Key Laboratory for Radiation Beam Technology and Materials Modification, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing, 100875 (China)

    2002-11-11

    A determination of the phase constituents of ceramic coatings produced on Al-Cu-Mg alloy by microarc discharge in alkaline solution was performed using x-ray diffraction. The profiles of the hardness, H, and elastic modulus, E, across the ceramic coating were determined by means of nanoindentation. In addition, a study of the influence of microarc oxidation coatings on the tensile properties of the aluminium alloy was also carried out. The results show that the H-and E-profiles are similar, and both of them exhibit a maximum value at the same depth of coating. The distribution of the {alpha}-Al{sub 2}O{sub 3} phase content determines the H- and E-profiles of the coatings. The tensile properties of 2024 aluminium alloy show less change after the alloy has undergone microarc discharge surface treatment.

  20. Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content

    Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta2O5 and Ta2O5-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility

  1. Superhydrophilicity and antibacterial property of a Cu-dotted oxide coating surface

    Nie Yining

    2010-09-01

    Full Text Available Abstract Background Aluminum-made settings are widely used in healthcare, schools, public facilities and transit systems. Frequently-touched surfaces of those settings are likely to harbour bacteria and be a potential source of infection. One method to utilize the effectiveness of copper (Cu in eliminating pathogens for these surfaces would be to coat the aluminum (Al items with a Cu coating. However, such a combination of Cu and Al metals is susceptible to galvanic corrosion because of their different electrochemical potentials. Methods In this work, a new approach was proposed in which electrolytic plasma oxidation (EPO of Al was used to form an oxide surface layer followed by electroplating of Cu metal on the top of the oxide layer. The oxide was designed to function as a corrosion protective and biocompatible layer, and the Cu in the form of dots was utilized as an antibacterial material. The antibacterial property enhanced by superhydrophilicity of the Cu-dotted oxide coating was evaluated. Results A superhydrophilic surface was successfully prepared using electrolytic plasma oxidation of aluminum (Al followed by electroplating of copper (Cu in a Cu-dotted form. Both Cu plate and Cu-dotted oxide surfaces had excellent antimicrobial activities against E. coli ATCC 25922, methicillin-resistant Staphylococcus aureus (MRSA ATCC 43300 and vancomycin-resistant Enterococcus faecium (VRE ATCC 51299. However, its Cu-dotted surface morphology allowed the Cu-dotted oxide surface to be more antibacterial than the smooth Cu plate surface. The enhanced antibacterial property was attributed to the superhydrophilic behaviour of the Cu-dotted oxide surface that allowed the bacteria to have a more effective killing contact with Cu due to spreading of the bacterial suspension media. Conclusion The superhydrophilic Cu-dotted oxide coating surface provided an effective method of controlling bacterial growth and survival on contact surfaces and thus reduces the

  2. Preparation of yttrium oxide coating by MOCVD as tritium permeation barrier

    Wu, Yunyi, E-mail: wuyunyi_80@163.com; He, Di; Zhang, Hua; Li, Shuai; Liu, Xiaopeng; Wang, Shumao; Jiang, Lijun

    2015-01-15

    Highlights: • Yttrium oxide coating was deposited on 316L substrate as hydrogen permeation barrier. • O:Y ratio of the 700 °C annealed coating corresponds well to the stoichiometric Y{sub 2}O{sub 3}. • The original precursor completely decomposed within the coating annealed at 700 °C. • The 700 °C annealed coating offers efficient inhibition to deuterium permeation. • Deuterium permeation of the 700 °C annealed coating is controlled by a hybrid regime. - Abstract: Yttrium oxide coatings were deposited on 316L substrate using metal organic chemical vapor deposition (MOCVD) technique with yttrium β-diketonates organometallic Y(tmhd){sub 3} as precursor. The different microstructures were obtained by annealing coatings at 700 °C or as-deposited. The film was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The hydrogen permeation inhibition performance of films was investigated by deuterium permeation experiment. The crystalline structure of the coatings depended on the post-anneal; the crystallite size of the coating increases and the surface exhibits compact surface morphology for the coatings post-annealed at 700 °C. The coating post-annealed at 700 °C has the correct oxygen/yttrium ratio corresponding well to the stoichiometric Y2O3, while some concentrations of carbon and hydrogen impurities were found in the as-deposited coating. The impurities are present in the form of unreacted or partially reacted precursor molecules due to the incomplete decomposition of the original precursor. The deuterium permeability of the coating improved obviously after post-anneal and was around 240–410 times less than that of the 316L stainless steel, which means efficient inhibition to deuterium permeation.

  3. Preparation of yttrium oxide coating by MOCVD as tritium permeation barrier

    Highlights: • Yttrium oxide coating was deposited on 316L substrate as hydrogen permeation barrier. • O:Y ratio of the 700 °C annealed coating corresponds well to the stoichiometric Y2O3. • The original precursor completely decomposed within the coating annealed at 700 °C. • The 700 °C annealed coating offers efficient inhibition to deuterium permeation. • Deuterium permeation of the 700 °C annealed coating is controlled by a hybrid regime. - Abstract: Yttrium oxide coatings were deposited on 316L substrate using metal organic chemical vapor deposition (MOCVD) technique with yttrium β-diketonates organometallic Y(tmhd)3 as precursor. The different microstructures were obtained by annealing coatings at 700 °C or as-deposited. The film was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The hydrogen permeation inhibition performance of films was investigated by deuterium permeation experiment. The crystalline structure of the coatings depended on the post-anneal; the crystallite size of the coating increases and the surface exhibits compact surface morphology for the coatings post-annealed at 700 °C. The coating post-annealed at 700 °C has the correct oxygen/yttrium ratio corresponding well to the stoichiometric Y2O3, while some concentrations of carbon and hydrogen impurities were found in the as-deposited coating. The impurities are present in the form of unreacted or partially reacted precursor molecules due to the incomplete decomposition of the original precursor. The deuterium permeability of the coating improved obviously after post-anneal and was around 240–410 times less than that of the 316L stainless steel, which means efficient inhibition to deuterium permeation

  4. Design of A Large Oxide Coated Cathode Plasma Source for Operation in High Magnetic Fields at the New LAPD

    Leneman, David

    2001-10-01

    We use a Barium Oxide coated cathode to supply accelerated electrons as an energy source to from our plasma. Oxide coated cathodes have been used for decades in vacuum tubes and plasma research. Most of these have been small (1 cm dia.) or designed to operate in a low magnetic field where the J×B \\unboldmath forces on them are negligible. At the new LAPD we will have large diameter plasma sources at both ends of the machine which must operate in a 3.5 kG ambient magnetic field. We have designed and built one such source which is 72 cm in diameter. It will supply up to 20 kA of pulsed beam current and uses a 1 m by 1 m, 2.5 kA (dc), 150 kW heater. Solutions to various engineering issues will be discussed. These pertain to differential thermal expansion over 1 m distances, J×B \\unboldmath forces on the heater and cathode, heat containment and uniformity of the oxide coating and of plasma production. These issues are important to any experimenter who plans to build an oxide coated plasma source.

  5. Reduction of ripening time of full-scale manganese removal filters with manganese oxide-coated media

    Bruins, J.H.; Petrusevski, B.; Slokar, Y.M.; Huysman, K.; Joris, K.; Kruithof, J.C.; Kennedy, M.D.

    2015-01-01

    Effective manganese removal by conventional aeration-filtration with virgin filter media requires a long ripening time. The aim of this study was to assess the potential of manganese oxide-coated media to shorten the ripening time of filters with virgin media, under practical conditions. A full scal

  6. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  7. Influence of mechanical abrasion of carbon adsorbents on aerodynamic resistance of filters of system of ventilation of NPS

    Influence of mechanical abrasion of granules on aerodynamic resistance of different carbon adsorbents at conditions similar to work of filters AU-1500 is studied. The change of fractional composition of the probed adsorbents by abrasion is determined. The obtained experimental data allow making conclusion about practicability using mixture of adsorbent Norit with different fractional composition for renewal of adsorbers of ventilation system of NPS.

  8. Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications

    Stone, D. S.; Bischof, M.; Aouadi, S. M., E-mail: samir.aouadi@unt.edu [Department of Material Science and Engineering, University of North Texas, Denton, Texas 76207 (United States); Gao, H.; Martini, A. [School of Engineering, University of California Merced, Merced, California 95343 (United States); Chantharangsi, C.; Paksunchai, C. [Department of Physics, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand)

    2014-11-10

    Silver tantalate (AgTaO{sub 3}) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750 °C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application.

  9. Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications

    Stone, D. S.; Gao, H.; Chantharangsi, C.; Paksunchai, C.; Bischof, M.; Martini, A.; Aouadi, S. M.

    2014-11-01

    Silver tantalate (AgTaO3) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750 °C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application.

  10. Study on electrolytic plasma discharging behavior and its influence on the plasma electrolytic oxidation coatings

    Hussein, Riyad Omran

    In this study, aluminum oxide was deposited on a pure aluminum substrate to produce hard ceramic coatings using a Plasma Electrolytic Oxidation (PEO) process. The process utilized DC, unipolar pulsed DC in the frequency range (0.2 KHz -- 20 KHz) and bipolar pulsed DC current modes. The effects of process parameters (i.e., electrolyte concentration, current density and treatment time) on the plasma discharge behavior during the PEO treatment were investigated using optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285 nm -- 900 nm). The emission spectra were recorded and plasma temperature profile versus processing time was constructed using the line intensity ratios method. Scanning Electron Microscopy (SEM) with energy dispersive x-ray analysis (EDS) was used to study the coating microstructure. It was found that the plasma discharge behavior significantly influenced the microstructure and the morphology of the oxide coatings. The main effect came from the strongest discharges which were initiated at the interface between the substrate and the coating. Through manipulation of process parameters to control or reduce the strongest discharge, the density and quality of the coating layers could be modified. This work demonstrated that by adjusting the ratio of the positive to negative pulse currents as well as their timing in order to eliminate the strongest discharges, the quality of the coatings was considerably improved.

  11. Wear resistance of micro-arc oxidation coatings on biomedical NiTi alloy

    Liu, F., E-mail: ryuufuku@hotmail.co [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, J.L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yu, D.Z. [Stomatological Medicine Center, Harbin Institute of Technology, Harbin 150001 (China); Wang, F.P. [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhao, L.C. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2009-11-13

    Protective coatings were successfully formed on biomedical NiTi alloy by micro-arc oxidation (MAO) using pulsed bipolar power supply. The coating surface exhibits a typical MAO porous structure, and the coating mainly consists of O, Al, Ti and Ni, with the atomic concentration of 65.11%, 27.77%, 2.20% and 2.8%, respectively. The thickness of MAO coating is about 24.0 {mu}m when the duration time of the MAO treatment was 90 min at 400 V constant voltage treatment. XRD analysis showed that micro-arc oxidation coating is composed of {gamma}-Al{sub 2}O{sub 3} and {alpha}-Al{sub 2}O{sub 3}. The wear resistance of the coatings was investigated by ball-on-disk friction test. The microhardness of the NiTi alloy is greatly enhanced due to the formation of Al{sub 2}O{sub 3} coating after micro-arc oxidation treatment. The friction coefficient of the coated NiTi is stable at 0.85 and the wear resistance is increased by 9 times compared with uncoated NiTi. The wear mechanism transforms from abrasive-dominant for the uncoated sample to adhesive-dominant for the coated sample.

  12. Stress controlled gas-barrier oxide coatings on semi-crystalline polymers

    Thin silicon oxide (SiOx) barrier coatings formed by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate) (PET) substrates were subjected to post-deposition annealing treatments in the temperature range for orientation relaxation of the polymer. The resulting change in coating internal stress state was measured by means of thermo-mechanical analyses, and its effect on the coating cohesive properties and coating/polymer adhesion was determined from the analysis of uniaxial fragmentation tests in situ in a scanning electron microscope, assuming a Weibull-type probability of failure and a perfectly plastic stress transfer at the SiOx/PET interface. The strain to failure and intrinsic fracture toughness of the ultrathin oxide coating were found to be as high as 5.7% and 10 J/m2, respectively, and its interfacial shear strength with PET was found to be close to 100 MPa. Annealing for 10 min at 150 deg. C did not modify the oxygen permeation properties of the SiOx/PET film, which suggests that the defect population of the oxide was not affected by the thermal treatment. In contrast, the coating internal compressive stress resulting from annealing was shown to increase by 40% the apparent coating cohesive properties and adhesion to the polymer

  13. Corrosion properties of steel protected by nanometre-thick oxide coatings

    Highlights: • 40–50 nm mixed alumina–tantala coatings were grown by atomic layer deposition. • Effects of substrate surface finish and oxide mix were analysed. • Nanolaminate stacks are better resistant to breakdown. • Localised corrosion occurs at pre-existing coating defects exposing substrate sites. • Substrate brushing and H2–Ar plasma pre-treatment hinder pit initiation. - Abstract: A comprehensive study of the corrosion properties of low alloy steel protected by 40–50 nm aluminium and tantalum mixed oxide coatings grown by atomic layer deposition is reported. Electrochemical and surface analysis was performed to address the effect of substrate surface finish and whether an oxide mixture or nanolaminate was used. There was no dissolution or breakdown for nanolaminate alumina/tantala stacks in acidic NaCl solution. Localised corrosion (pitting) took place when defects exposing the substrate pre-existed in the coating. Substrate pre-treatment by brushing and H2–Ar plasma was instrumental to block or slow down pit initiation by reducing the defect dimensions

  14. Effects of oxide coating on the growth of single grain YBCO bulk superconductors

    Surface oxide coating and bottom inserting of oxide plates have been conducted to top seeded melt growth (TSMG) processed YBa2Cu3O7-y (Y123) bulk superconductors with an aim of controlling the Y123 nucleation and growth. The coating medium for surfaces was Yb2O3 solution and the bottom inserts were Yb2O3/Y2O3 powder compact. Many vertical cracks were found to develop at the compact/insert interfaces when an Yb2O3 insert was used, but the crack evolution was greatly reduced when a (Yb2O3 + Y2O3) insert was used. The formation of the vertical cracks is ascribed to the difference in thermal expansion between the YBCO compact and bottom insert. Presence of vertical cracks was found to be crucial to the trapped magnetic field and levitation forces of single grain YBCO bulk superconductors. The Y123 nucleation and growth in TSMG-processed YBCO bulk superconductors were successfully controlled by conducting surface coating and bottom plating using a (Yb2O3 + Y2O3) insert and as a result, the levitation properties were much enhanced.

  15. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  16. Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content

    Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui; Chou, Yu-Kai [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y. C. [Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

    2014-03-15

    Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility.

  17. Molecular Adsorber Coating

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  18. PENGARUH KOMPOSOSI LAPISAN PADA PERMUKAAN GLOBULA MINYAK EMULSI SEBELUM PENGERINGAN SEMPROT TERHADAP SIFAT-SIFAT MIKROKAMSUL TRIGLISERIDA KAYA ASAM LEMAK W-3 [The Effect of the Composition of Adsorbed Layer at Globule Interface of -3 Fatty Acids Enriched Triglyceride Prior to Spray Drying on its Microcapsule Properties

    Moch Adnan2

    2005-04-01

    Full Text Available Emulsification is the critical factor in microencapsulation by spray drying method. Sodium caseinate is a protein with good emulsifying properties. The properties could be improved by phospholipids addition in the emulsification. Phospholipids addition which stabilized oil globule might change the composition of adsorbed layer.This research was conducted to analyze the changes in composition at oil globule interface by analyzing emulsion systems of triglyceride enriched by -3 fatty acids at 5% (w/v stabilized by sodium caseinate (10% w/v and addition of phospholipids at 0; 0,5; 1,0; 1,5; 2,0; and 2,5% (w/v. The changes in composition of adsorbed layer could be determined from the changes in phospholipids and adsorbed protein concentrations at oil globule interface. Analyses were done to measure the possibility of casein-phospholipids complex, phospholipids and protein adsorption concentration at interface, and adsorbed protein.The increase of phospholipids concentration in the emulsions stabilized by sodium caseinate changed the composition of adsorbed layer at interface. There was phospholipids increase and adsorbed protein decrease at oil globule interface. These changes were caused by casein-phospholipids complex which that decreased surface activity and displacement protein by phospholipids that was adsorbed at oil globule interface.Changes of composition of casein-phospholipids at oil globule prior to microcapsulation process caused changes in the properties of microcapsule produced. The increasing phospholipids and decreasing casein concentrations at oil globule interface decreased the quality of the microcapsule, including decreasing in microencapsulation efficiency, in oxidative stability, and decreasing in EPA+DHA content.

  19. Magnetic composite of Fe3O4 and activated carbon as a adsorbent for separation of trace Sr(II) from radioactive wastewater

    Magnetic adsorbent of Fe3O4 and activated carbon (Fe3O4/AC) was prepared by chemical coprecipitation technique, and was characterized by SEM, TEM, BET, XRD, and VSM techniques in details. The adsorption results of Sr(II) on Fe3O4/AC revealed that Sr(II) adsorption on Fe3O4/AC surface was an spontaneous and endothermic process, and can be well described by the pseudo-second-order model. The adsorption of Sr(II) on Fe3O4/AC increased with increasing pH, and decreased with increasing ionic strength. Fe3O4/AC can be easily separated from aqueous solution with an external magnetic field after application. (author)

  20. Effect of fulvic acid on adsorptive removal of Cr(VI) and As(V) from groundwater by iron oxide-based adsorbents

    Uwamariya, V.

    2015-05-15

    Abstract Natural contamination has become a challenging problem in drinking water production due to metal contamination of groundwater throughout the world, and arsenic and chromium are well-known toxic elements. In this study, iron oxide-coated sand (IOCS) and granular ferric hydroxide (GFH) were used to study the effects of fulvic acid (FA) on the adsorptive removal of Cr(VI) and As(V) from synthetic groundwater. IOCS and GFH were characterized by SEM/EDS, and experiments were performed at different pH levels (6, 7, and 8). The surface of IOCS and GFH showed a high content of Fe and O (75 and 60 % of the atomic composition, respectively), suggesting that they can highly effectively adsorb Cr(VI) and As(V). Adsorption tests with the simultaneous presence of As(V) and FA, on the one hand, and Cr(VI) with FA, on the other hand, revealed that the role of FA on chromate and arsenate adsorption was insignificant at almost all pH values investigated with both adsorbents. A small influence as a result of FA was only observed for the removal of As(V) by IOCS at pH 6 with a decrease of 13 and 23 % when 2 and 5 mg/l were added to the synthetic water, respectively. It was also found that organic matter (OM) was leached from the IOCS during batch adsorption experiments. The use of FEEM revealed that humic-like, fulvic-like, and protein-like organic matter fractions are present on the IOCS surface. © 2015 Springer International Publishing Switzerland.

  1. Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators

    Dave, V. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India); Gupta, H.O. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Chandra, R., E-mail: ramesfic@gmail.com [Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India)

    2014-03-01

    Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO{sub 2} film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO{sub 2} films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: We report the structural, optical and electrical properties of nanostructured hydrophobic inorganic hafnium oxide coating for outdoor glass insulator using DC sputtering technique to combat contamination problem. The properties were studied as a function of DC power. The characterization of the films was done using X-ray diffraction, EDS, surface profilometer, AFM, impedance analyser and water contact angle measurement system. The DC power was varied from 30 to 60 W and found to have a great impact on the properties of hafnium oxide. All the deposited samples were polycrystalline with nanostructured hydrophobic surfaces. The intensity of crystallinity of the film was found to be dependent on sputtering power and hydrophobicity was correlated to the nanoscale roughness of the films. The optical property reveals 80% average transmission for all the samples. The refractive index was found in the range of 1.85–1.92, near to the bulk value. The band gap calculated from transmission data was >5.3 eV for all deposited samples ensuring dielectric nature of the films. Surface energy calculated by two methods was found minimum for the film deposited at 50 W sputtering power. The resistivity was also high enough (∼10{sup 4} Ω cm) to hinder the flow of leakage current through the film. The dielectric constant (ε) was found to be thickness dependent and also high enough (ε{sub max} = 23.12) to bear the large electric field of outdoor insulators.

  2. UV protective zinc oxide coating for biaxially oriented polypropylene packaging film by atomic layer deposition

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kääriäinen, Tommi, E-mail: tommi.kaariainen@colorado.edu [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Johansson, Petri, E-mail: petri.johansson@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Kotkamo, Sami, E-mail: sami.kotkamo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Seppänen, Tarja, E-mail: tarja.seppanen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Cameron, David C., E-mail: david.cameron@miktech.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2014-11-03

    Biaxially oriented polypropylene (BOPP) packaging film was coated with zinc oxide (ZnO) coatings by atomic layer deposition (ALD) in order to protect the film from UV degradation. The coatings were made at a process temperature of 100 °C using diethylzinc and water as zinc and oxygen precursors, respectively. The UV protective properties of the coatings were tested by using UV–VIS and infrared spectrometry, differential scanning calorimetry (DSC) and a mechanical strength tester, which characterised the tensile and elastic properties of the film. The results obtained with 36 and 67 nm ZnO coatings showed that the ZnO UV protective layer is able to provide a significant decrease in photodegradation of the BOPP film under UV exposure. While the uncoated BOPP film suffered a complete degradation after a 4-week UV exposure, the 67 nm ZnO coated BOPP film was able to preserve half of its original tensile strength and 1/3 of its elongation at break after a 6-week exposure period. The infrared analysis and DSC measurements further proved the UV protection of the ZnO coatings. The results show that a nanometre scale ZnO coating deposited by ALD is a promising option when a transparent UV protection layer is sought for polymer substrates. - Highlights: • Atomic layer deposited zinc oxide coatings were used as UV protection layers. • Biaxially oriented polypropylene (BOPP) film was well protected against UV light. • Formation of UV degradation products in BOPP was significantly reduced. • Mechanical properties of the UV exposed BOPP film were significantly improved.

  3. Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators

    Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO2 film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO2 films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: We report the structural, optical and electrical properties of nanostructured hydrophobic inorganic hafnium oxide coating for outdoor glass insulator using DC sputtering technique to combat contamination problem. The properties were studied as a function of DC power. The characterization of the films was done using X-ray diffraction, EDS, surface profilometer, AFM, impedance analyser and water contact angle measurement system. The DC power was varied from 30 to 60 W and found to have a great impact on the properties of hafnium oxide. All the deposited samples were polycrystalline with nanostructured hydrophobic surfaces. The intensity of crystallinity of the film was found to be dependent on sputtering power and hydrophobicity was correlated to the nanoscale roughness of the films. The optical property reveals 80% average transmission for all the samples. The refractive index was found in the range of 1.85–1.92, near to the bulk value. The band gap calculated from transmission data was >5.3 eV for all deposited samples ensuring dielectric nature of the films. Surface energy calculated by two methods was found minimum for the film deposited at 50 W sputtering power. The resistivity was also high enough (∼104 Ω cm) to hinder the flow of leakage current through the film. The dielectric constant (ε) was found to be thickness dependent and also high enough (εmax = 23.12) to bear the large electric field of outdoor insulators

  4. Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes.

    Huang, Li-Zhi; Hansen, Hans Christian B; Bjerrum, Morten Jannik

    2016-04-01

    Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30μAcm(-2) was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400μM of the nitroaromatic compound at a potential of -0.7V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant=0.28h(-1)) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant=6.9μM h(-1)). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and low over potential. PMID:26716570

  5. Measurements of Total Hemispherical Emissivity of Several Stably Oxidized Metals and Some Refractory Oxide Coatings

    Wade, William R.

    1959-01-01

    A description of the apparatus and methods used for obtaining total hemispherical emissivity is presented, and data for several stably oxidized metals are included. The metals which were tested included type 347 stainless steel, tungsten, and Haynes alloys B, C, X, and 25. No values of emissivity were obtained for tungsten or Haynes alloy B because of the nature of the oxides produced. The refractory oxide coatings tested were flame-sprayed alumina and zirconia. The results of the investigation indicate that strongly adherent, oxidized surfaces of a high stable emissivity can be produced on type 347 stainless steel for which the total hemispherical emissivity varied from 0.87 to 0.91 for temperatures from 600 F to 2,000 F. For this same temperature range, the Haynes alloys tested showed values of total hemispherical emissivity from 0.90 to 0.96 for alloy C, from 0.85 to 0.88 for alloy X, and from 0.85 to 0.89 for alloy 25. Haynes alloy B and tungsten formed nonadherent oxides at elevated temperatures and, therefore, stable emissivities were not obtained. The results obtained for the flame-sprayed ceramics (alumina and zirconia) showed considerably higher values of total emissivity than those measured for coatings applied by other methods. Emissivity values ranging from 0.69 to 0.44 for aluminum oxide and from 0.62 to 0.44 for zirconium oxide were measured for temperatures from 800 F to 2,000 F.

  6. UV protective zinc oxide coating for biaxially oriented polypropylene packaging film by atomic layer deposition

    Biaxially oriented polypropylene (BOPP) packaging film was coated with zinc oxide (ZnO) coatings by atomic layer deposition (ALD) in order to protect the film from UV degradation. The coatings were made at a process temperature of 100 °C using diethylzinc and water as zinc and oxygen precursors, respectively. The UV protective properties of the coatings were tested by using UV–VIS and infrared spectrometry, differential scanning calorimetry (DSC) and a mechanical strength tester, which characterised the tensile and elastic properties of the film. The results obtained with 36 and 67 nm ZnO coatings showed that the ZnO UV protective layer is able to provide a significant decrease in photodegradation of the BOPP film under UV exposure. While the uncoated BOPP film suffered a complete degradation after a 4-week UV exposure, the 67 nm ZnO coated BOPP film was able to preserve half of its original tensile strength and 1/3 of its elongation at break after a 6-week exposure period. The infrared analysis and DSC measurements further proved the UV protection of the ZnO coatings. The results show that a nanometre scale ZnO coating deposited by ALD is a promising option when a transparent UV protection layer is sought for polymer substrates. - Highlights: • Atomic layer deposited zinc oxide coatings were used as UV protection layers. • Biaxially oriented polypropylene (BOPP) film was well protected against UV light. • Formation of UV degradation products in BOPP was significantly reduced. • Mechanical properties of the UV exposed BOPP film were significantly improved

  7. Transporting method for adsorbing tower and the adsorbing tower

    A cylindrical plastic bag is disposed to the upper surface of an adsorbing tower so as to surround a suspending piece. One opening of the bag is sealed, and other opening is secured in a sealed state to a bag holding portion disposed to glove box at a gate for the adsorbing tower box. The adsorbing tower is transported into the glove box, and after the completion of the operation of the adsorbing tower, the adsorbing tower is taken out in a state that the bag is restricted and sealed at a portion below the adsorbing tower. The bag may be made of a vinyl plastic, the bag holding portion may be a short-cylindrical protrusion, and may have an O-ring groove at the outer surface. Even if the adsorbing tower is heavy, the adsorbing tower can be carried out easily in a state where it is sealed gas tightly. (N.H.)

  8. Ionogenic adsorbents based on local raw materials for radiation protection

    The successful management of uranium wastes and creating the conditions for effective rehabilitation activities require special adsorbents capable of holding on the surface complexes, including radioactive elements. Currently tested and have shown promising synthetic adsorbents based pitted apricot fruits and other fruit plants. This report presents data for the establishment of ionic type available adsorbents based on Tajikistan coal. As the base for the creation of this type of adsorbent were taken the coal of the 'Ziddi' deposits. As follows from our data on the chemical composition, the studied coals contain more than 20% of the ash. According to the available literature theses ashes contains various minerals compositions that can form the adsorbent's active surface. Thus, the model for this type of activated carbon can serve as a mixture of zeolite, ion exchange resins and activated carbon itself.

  9. Size selective hydrophobic adsorbent for organic molecules

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  10. Thermal and chemical stability studies of protective plasma sprayed yttrium oxide coatings on tantalum substrate against liquid uranium

    Yttrium oxide was deposited on tantalum substrates (40 mm x 8 mm x 1 mm thk) by atmospheric plasma spray technique with out any bond coat using optimized coating parameters. Resistance to thermal shock was evaluated upto 6 cycles prior to the chemical compatibility experiments. Thermal shock qualified batch of coupons were tested for compatibility against liquid uranium at 1573 K upto 200 hrs in oxide coating exhibits excellent corrosion resistance vacuum. Experimental results show that yttrium against liquid uranium at 1573 K. (author)

  11. Removal of dissolved heavy metals from pre-settled stormwater runoff by iron-oxide coated sand (IOCS)

    Møller, J.; Ledin, Anna; Mikkelsen, Peter Steen

    2002-01-01

    Sorption to iron-oxide coated sand (IOCS) is a promosing technology for removal of the dissolved heavy metal fraction in stormwater runoff. The development of a new technology is necessary since studies of stormwater runoff from traffic areas indicate that an oil separator and detention pond may...... leterature (Pb=20, Cu=40, Zn=110, and Cr=15 ppb). Column experiments were conducted to test the influence of the infiltration rate (1 or 3 m/h) and the type of iron(hydr)oxide mineral (amorphous ferrihydrite and goethite coated sand). The results show that at least 90% of lead, copper and zinc can be removed...

  12. Experimental Study of the Micro-Arc Oxide Coating Effect on Thermal Properties of an Aluminium Alloy Piston Head

    N.Yu. Dudareva

    2015-09-01

    Full Text Available The purpose of the present study is to investigate the influence of differently sized microarc oxidation coatings, applied to the bottom of pistons made with an Al-12Si-Mg-Cu-Ni alloy, on its thermal properties by simulating the operation of a real engine. This study is based on the premise that the alumina coating thickness affects the heat transfer and temperature distribution in the piston. The analysis of thermal properties of pistons and suggestions for the optimal thermal barrier coating thickness are presented.

  13. Screening the toxicity of phosphorous-removal adsorbents using a bioluminescence inhibition test.

    Duranceau, Steven J; Biscardi, Paul G; Barnhill, Danielle K

    2016-04-01

    When found in excess, phosphorus (P) has been linked to surface water eutrophication. As a result, adsorbents are now used in P remediation efforts. However, possible secondary toxicological impacts on the use of new materials for P removal from surface water have not been reported. This study evaluated the toxicity of adsorbent materials used in the removal of P from surface water including: fly ash, bottom ash, alum sludge, a proprietary mix of adsorbents, and a proprietary engineered material. Toxicity screening was conducted by performing solid-liquid extractions (SLEs) followed by the bacterial bioluminescence inhibition test with a Microtox® M500. Of the materials tested, the samples extracted at lower pH levels demonstrated higher toxicity. The material exhibiting the most toxic response was the iron and aluminum oxide coated engineered material registering a 66-67% 15-min EC50 level for pH 4 and 5 SLEs, respectively. However, for SLEs prepared at pH 7, toxic effects were not detected for this engineered material. Fly ash and bottom ash demonstrated between 82 and 84% 15-min EC50 level, respectively, for pH 4 SLE conditions. Dried alum sludge and the proprietary mix of adsorbents were classified as having little to no toxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 489-495, 2016. PMID:25348491

  14. High performance Mo adsorbent PZC

    Anon.

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  15. 钌镧氧化物涂层析氯反应动力学比较研究%Comparative Study on Kinetics of Chlorine Evolution Reaction for Ru-La-O Oxide Coatings

    龙萍; 许立坤; 崔秀芳; 金国

    2015-01-01

    通过热分解法制备了Ti/RuO2和Ti/Ru-La-O氧化物涂层,利用微分电容和极化曲线等实验方法对涂层Clˉ特性吸附、La对RuO2涂层析氯反应过程的影响及反应机理进行了研究.结果表明,在NaCl溶液中,涂层表面存在Clˉ的特性吸附,这种特性吸附对析氯反应的动力学产生了影响,导致Tafel斜率上升,反应级数下降,加入La使氧化钌涂层的过电位下降,交换电流密度增大,有利于析氯反应的进行.本文对涂层存在的两种可能反应机理进行了比较分析,认为在中性NaCl溶液中析氯反应是由2≡S·OCl*(rds→)≡S·O +Cl2过程控制的.%The Ti/RuO2 and Ti/Ru-La-O oxide coatings were prepared by thermal decomposition of the metal chlorides in the precursor solution. The specific adsorption of Clˉ on coatings, the effect of La on the chlorine evo-lution reactions (ClER) and the kinetic mechanism were investigated by using differential capacity (DC) and po-larization curves (PC). Results show that the coating surface exhibits significantly specific adsorption of Clˉ in NaCl neutral solution, which has an influence on the kinetics of the chlorine evolution process, resulting in an in-crease of the Tafel slope and a decrease of the reaction order. The addition of lanthanum reduces the overpotential of Ti/RuO2 coating and enhances the exchange current density, which improves the chlorine evolution reaction of the coatings. Both kinetic mechanisms of recombination and electrochemical desorption of adsorbed intermediate species for the coatings are comparatively studied. It is confirmed that the Chlorine evolution reaction on Ru-La-O oxide coatings in NaCl neutral solution is controlled by the process of 2≡ S· OCl* (rds→)≡ S·O +Cl2.

  16. Alloy Films Deposited by Electroplating as Precursors for Protective Oxide Coatings on Solid Oxide Fuel Cells Metallic Interconnect Materials

    Johnson, Christopher; Gemmen, R.S.; Cross, Caleb

    2006-10-01

    The successful development of stainless steel interconnects for intermediate temperature solid oxide fuel cells (SOFC) may be the materials breakthrough that makes SOFC technology truly commercial. Many of the ferritic stainless steels, however, suffer from a relatively high area specific resistance (ASR) after long exposure times at temperature and the Cr in the native oxide can evaporate and contaminate other cell components. Conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. In the present study electrochemical deposition of binary alloys followed by oxidation of the alloy to form protective and conductive oxide layers is examined. Results are presented for the deposition of Mn/Co and Fe/Ni alloys via electroplating to form a precursor for spinel oxide coating formation. Analysis of the alloy coatings is done by SEM, EDS and XRD.

  17. Removal of dissolved heavy metals from pre-settled stormwater runoff by iron-oxide coated sand (IOCS)

    Møller, J.; Ledin, Anna; Mikkelsen, Peter Steen

    2002-01-01

    Sorption to iron-oxide coated sand (IOCS) is a promosing technology for removal of the dissolved heavy metal fraction in stormwater runoff. The development of a new technology is necessary since studies of stormwater runoff from traffic areas indicate that an oil separator and detention pond may...... not guarantee that emission limit values set by the Danish EPA are satisfied. Runoff water was sampled from an urban highway, allowed to settle for 24 hours to simulate the effect of a detention pond, and finally spiked with metals to ensure concentration levels similar to high levels reported in the...... leterature (Pb=20, Cu=40, Zn=110, and Cr=15 ppb). Column experiments were conducted to test the influence of the infiltration rate (1 or 3 m/h) and the type of iron(hydr)oxide mineral (amorphous ferrihydrite and goethite coated sand). The results show that at least 90% of lead, copper and zinc can be removed...

  18. Influence of albumin and inorganic ions on electrochemical corrosion behavior of plasma electrolytic oxidation coated magnesium for surgical implants

    Wan, Peng; Lin, Xiao; Tan, LiLi; Li, Lugee; Li, WeiRong; Yang, Ke

    2013-10-01

    Magnesium and its alloys are of great interest for biodegradable metallic devices. However, the degradation behavior and mechanisms of magnesium treated with coating in physiological environment in the presence of organic compound such as albumin have not been elucidated. In this study, the plasma electrolytic oxidation coated magnesium immersed in four different simulated body fluids: NaCl, PBS and with the addition of albumin to investigate the influence of protein and inorganic ions on degradation behavior by electrochemical methods. The results of electrochemical tests showed that aggressive corrosion took place in 0.9 wt.% NaCl solution; whereas albumin can act as an inhibitor, its adsorption impeded further dissolution of the coating. The mechanism was attributed to the synergistic effect of protein adsorption and precipitation of insoluble salts.

  19. Positronium chemistry in porous adsorbents

    Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

  20. Sorptive removal of cobalt, strontium and cesium onto manganese and iron oxide-coated montmorillonite from groundwater

    Applicability of montmorillonite, manganese oxide-coated montmorillonite (MOCM) and iron oxide-coated montmorillonite (IOCM) as backfill materials in permeable reactive barrier (PRB) to remediate contaminated groundwater was investigated. Single- and bi-solute competitive sorptions of Co, Sr and Cs were conducted. The Freundlich, Langmuir and Dubinin-Radushkevich models fitted the single-solute sorption data well (R2 > 0.95). Maximum sorption capacities (qmL) of Co and Sr predicted by the Langmuir model were in the order of MOCM (0.37 mmol/g for Co and 0.28 mmol/g for Sr) > montmorillonite (0.27 mmol/g for Co and 0.19 mmol/g for Sr) ∼ IOCM (0.23 mmol/g for Co and 0.21 mmol/g for Sr), while those of Cs were in the order of montmorillonite (1.11 mmol/g) > MOCM (0.68 mmol/g) > IOCM (0.62 mmol/g). In the bi-solute sorptions, the sorbed amount of one solute decreased due to the presence of the other competing metal ion. Langmuir model parameters for single-solute (qmL and bL) and bi-solute (qmL* and bL*) sorptions were compared to analyze the effect of competition between the metal ions. The competitive Langmuir (R2 > 0.81) and P-factor (R2 > 0.82) models predicted the bi-solute competitive sorption data well but not the SRS model (0.003 2 < 0.97). (author)

  1. The origin of ferro-manganese oxide coated pumice from the Central Indian Ocean Basin

    Pattan, J.N.; Pearce, N.J.G.; Parthiban, G.; Smith, V.C.; Mudholkar, A; Rao, N.R.

    approx100 times enriched compared to chondritic abundance and exhibits a pronounced negative Eu-anomaly. Both the partially and fully coated pumice clasts have a similar composition, but this, and their, glass and mineral (orthopyroxene) chemistry differs...

  2. Substrate-adsorbate coupling in CO-adsorbed copper

    Lewis, S P; Lewis, Steven P.; Rappe, Andrew M.

    1996-01-01

    The vibrational properties of carbon monoxide adsorbed to the copper (100) surface are explored within density functional theory. Atoms of the substrate and adsorbate are treated on an equal footing in order to examine the effect of substrate--adsorbate coupling. This coupling is found to have a significant effect on the vibrational modes, particularly the in-plane frustrated translation, which mixes strongly with substrate phonons and broadens into a resonance. The predicted lifetime due to this harmonic decay mechanism is in excellent quantitative agreement with experiment.

  3. Arsenic remediation of drinking water using iron-oxide coated coal bottom ash

    MATHIEU, JOHANNA L.; GADGIL, ASHOK J.; ADDY, SUSAN E.A.; KOWOLIK, KRISTIN

    2010-06-01

    We describe laboratory and field results of a novel arsenic removal adsorbent called 'Arsenic Removal Using Bottom Ash' (ARUBA). ARUBA is prepared by coating particles of coal bottom ash, a waste material from coal fired power plants, with iron (hydr)oxide. The coating process is simple and conducted at room temperature and atmospheric pressure. Material costs for ARUBA are estimated to be low (~;;$0.08 per kg) and arsenic remediation with ARUBA has the potential to be affordable to resource-constrained communities. ARUBA is used for removing arsenic via a dispersal-and-removal process, and we envision that ARUBA would be used in community-scale water treatment centers. We show that ARUBA is able to reduce arsenic concentrations in contaminated Bangladesh groundwater to below the Bangladesh standard of 50 ppb. Using the Langmuir isotherm (R2 = 0.77) ARUBA's adsorption capacity in treating real groundwater is 2.6x10-6 mol/g (0.20 mg/g). Time-to-90percent (defined as the time interval for ARUBA to remove 90percent of the total amount of arsenic that is removed at equilibrium) is less than one hour. Reaction rates (pseudo-second-order kinetic model, R2>_ 0.99) increase from 2.4x105 to 7.2x105 g mol-1 min-1 as the groundwater arsenic concentration decreases from 560 to 170 ppb. We show that ARUBA's arsenic adsorption density (AAD), defined as the milligrams of arsenic removed at equilibrium per gram of ARUBA added, is linearly dependent on the initial arsenic concentration of the groundwater sample, for initial arsenic concentrations of up to 1600 ppb and an ARUBA dose of 4.0 g/L. This makes it easy to determine the amount of ARUBA required to treat a groundwater source when its arsenic concentration is known and less than 1600 ppb. Storing contaminated groundwater for two to three days before treatment is seen to significantly increase ARUBA's AAD. ARUBA can be separated from treated water by coagulation and clarification, which is expected to

  4. Functional metal oxide coatings by molecule-based thermal and plasma chemical vapor deposition techniques.

    Mathur, S; Ruegamer, T; Donia, N; Shen, H

    2008-05-01

    Deposition of thin films through vaccum processes plays an important role in industrial processing of decorative and functional coatings. Many metal oxides have been prepared as thin films using different techniques, however obtaining compositionally uniform phases with a control over grain size and distribution remains an enduring challenge. The difficulties are largely related to complex compositions of functional oxide materials, which makes a control over kinetics of nucleation and growth processes rather difficult to control thus resulting in non-uniform material and inhomogeneous grain size distribution. Application of tailor-made molecular precursors in low pressure or plasma-enhanced chemical vapor deposition (CVD) techniques offers a viable solution for overcoming thermodynamic impediments involved in thin film growth. In this paper molecule-based CVD of functional coatings is demonstrated for iron oxide (Fe2O3, Fe3O4), vanadium oxide (V2O5, VO2) and hafnium oxide (HfO2) phases followed by the characterization of their microstructural, compositional and functional properties which support the advantages of chemical design in simplifying deposition processes and optimizing functional behavior. PMID:18572690

  5. Silicon effects on formation of EPO oxide coatings on aluminum alloys

    Wang, L. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada); Nie, X. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada)]. E-mail: xnie@uwindsor.ca

    2006-01-03

    Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al-Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys ({approx} 17% Si) and hypoeutectic 319 alloys ({approx} 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms.

  6. Preparation of micro-arc oxidation coatings on magnesium alloy and its thermal shock resistance property

    JIANG Zhaohua; ZENG Xiaobin; YAO Zhongping

    2006-01-01

    In the NaAlO2-Na2SiO3 compound system, the ceramic coatings were prepared on magnesium alloy by micro-arc oxidation. The morphology, phase composition, and thermal shock resistance of the ceramic coatings were studied by scanning electron microscope, X-ray diffraction and thermal shock tests, respectively. The results showed that the ceramic coating contains MgO, MgAl2O4, as well as a little amount of Mg2SiO4. The thickness of the ceramic coatings induced ceramic coating is the best. The hardness of the ceramic coating is up to 10 GPa or so.

  7. MODIFICATION OF CARBONACEOUS ADSORBENTS WITH MANGANESE COMPOUNDS

    Irina Ginsari; Larisa Postolachi; Vasile Rusu; Oleg Petuhov; Tatiana Goreacioc; Tudor Lupascu; Raisa Nastas

    2015-01-01

    Four series of samples containing manganese supported carbonaceous adsorbents were prepared. Obtained results reveal the importance of surface chemistry of carbonaceous adsorbents on the manganese loading.

  8. Preparation and characterization of a novel adsorbent for removing lipophilic organic from water

    LIU; Huijuan; DAI; Ruihua; QU; Jiuhui; RU; Jia

    2005-01-01

    A novel composite adsorbent containing a kind of lipid-triolein is studied. The adsorbent is prepared by embedding triolein into cellulose acetate (CA) sphere. The preparation method, the physical-chemical properties of the adsorbent and the removal efficiency of two organochlorinated pesticides are studied. The adsorbent is stable in water and no triolein leaks into water for 465 h soaking. The adsorbent has high adsorption capacity for organochlorinated pesticides such as dieldrin and aldrin. The results suggest that triolein-containing adsorbent could serve as a good adsorbent for lipophilic organic pollutants. The adsorption rate for lipophilic pollutants is very fast and has relation with the logKow of the compounds.

  9. Green Adsorbents for Wastewaters: A Critical Review

    George Z. Kyzas

    2014-01-01

    Full Text Available One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i dyes; (ii heavy metals; (iii phenols; (iv pesticides and (v pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i agricultural sources and by-products (fruits, vegetables, foods; (ii agricultural residues and wastes; (iii low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources. These “green adsorbents” are expected to be inferior (regarding their adsorption capacity to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc., but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful topics such as: (i adsorption capacity; (ii kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes and (iii critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry with economic analysis and perspectives of the use of green adsorbents.

  10. Characterization of calcium containing plasma electrolytic oxidation coatings on AM50 magnesium alloy

    An attempt was made to produce calcium containing plasma electrolytic oxidation (PEO) coatings on AM50 magnesium alloy using an alkaline electrolyte. This study was performed in three alkaline electrolytes containing calcium hydroxide and sodium phosphate with three different mass ratios viz., 1:2.5, 1:5 and 1:7.5. All the three coatings produced were found to contain Ca and P in appreciable amounts. The concentration of P was found to be higher in the coatings obtained in the electrolytes with higher concentration of phosphate ions. Even though all the three coatings were found to be constituted with magnesium oxide and magnesium phosphate phases, X-ray diffraction analyses revealed that the phase composition was influenced by the phosphate ion concentration/conductivity of the electrolyte. Further, the PEO coating obtained in the 1:7.5 ratio electrolyte was found to contain di-calcium phosphate (monetite) and calcium peroxide phases, which were absent in the other two coatings. Potentiodynamic polarization studies performed in 0.1 M NaCl solution showed that the coatings obtained from the 1:5 ratio electrolyte possessed a superior corrosion resistance, which is attributed to the combined effect of thickness, compactness and phase/chemical composition of this coating.

  11. Evolution of a Two-Layer Oxide Coating on the Steel Surface of the Primary Coolant Circuit in the Course of Nuclear Power Plant Operation

    Alekseev, V. V.; Orlova, E. A.; Kozlov, F. A.; Varseev, E. V.

    2016-01-01

    An analysis of the laws governing mass transfer in a uniform oxide coating on the surface of a circuit is presented. As a result of calculations, the distribution of the fluxes of magnetite and of the particles of corrosion product suspensions depositing on the surface of the throughput section, as well as the distribution of the fluxes of dissolved iron, emerging from steel, along the length of the hydraulic system of the primary coolant circuit of the BREST-type plant, have been refined. The laws governing the process of mass transfer in the BREST-type primary coolant circuit with account for the oxide coating thickness variable in time have been obtained. The distribution of the thicknesses of the magnetite and spinel layers on the steel surface along the length of the BREST-type circulation loop after 365 days from the start of operation in a nominal regime is shown.

  12. Adsorption-dissolution reactions affecting the distribution and stability of CoIIEDTA in ion oxide-coated sand

    The time-variant chemical behavior of CoIIEDTA (and other metal-EDTA complexes) was investigated in suspensions of iron oxide-coated sand to identify equilibrium and kinetic reactions that control the mobility of MeII-EDTA complexes in subsurface environments. Batch experiments were conducted to evaluate the adsorption as a function of pH, concentration, and time and to quantify the rate-controlling step(s) of dissolution of the iron oxide by EDTA complexes. Ionic Co2+ exhibited typical cation-like adsorption, whereas MeIIEDTA adsorption was ligand-like, increasing with decreasing pH. Adsorption isotherms for all reactive species exhibited Langmuir behavior, with site saturation occurring at molar values of tot. The adsorption of MeIIEDTA enhanced the apparent solubility of the iron oxide phase, which destabilized the CoIIEDTA complex, liberating Co2+ and FeIIIEDTA. The dissolution rate was an order of magnitude slower at pH 6.5 than at pH 4.5 and was influenced by the re-adsorption of solubilized FeIIIEDTA. Two multireaction kinetic models were developed that each included Langmuir adsorption for Co2+ and metal-EDTA species but differed in their depiction of the dissolution mechanism (i.e., ligand-versus proton-promoted dissolution). 45 refs., 8 figs., 6 tabs

  13. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning. Final report, August 1990--March 1992

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  14. Effects of fluoride on the structure and properties of microarc oxidation coating on aluminium alloy

    Wang Zhijiang [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wu Lina [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Cai Wei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shan A [Chemical Engineering College, Inner Mongolia University of Technology, Hohhot 010051 (China); Jiang Zhaohua, E-mail: jiangzhaohua@hit.edu.c [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2010-08-27

    The composition of electrolyte plays a key role in the structure and properties of the synthesized ceramic coating by microarc oxidation (MAO) process. In the present study, F{sup -} ion, the smallest size among the negative ions, is chosen as the additive. The effects of F{sup -} ion on the structure and properties of the formed ceramic coating have been investigated in detail. Inspection of the scanning electron microscopy (SEM) and X-ray diffraction (XRD) suggests that the addition of fluoride during MAO process can decrease the porosity of the surface and enhance the density of the coating. These structure features lead to the corrosion resistances and tribological properties greatly improved. Based on the experimental results and the characteristics of MAO process, the influence mechanism of F{sup -} is proposed.

  15. Study on wear behavior of plasma electrolytic oxidation coatings on aluminum alloy

    CUI Shihai; HAN Jianmin; LI Weijing; KANG Suk-Bong; LEE Jung-Moo

    2006-01-01

    Thick and hard ceramic coatings were fabricated on A356 aluminum alloy by using plasma electrolytic oxidation(PEO) technique.The microstructure and phase composition of the PEO coatings were examined by using SEM and XRD method.It is found that the PEO coatings are mainly composed of crystalline α-Al2O3 and mullite.The dry sliding wear test of PEO coatings were carried out on a ring-on-ring wear machine.Results shows that there is hardly no wear loss of polished PEO coatings while the wear rate of uncoated aluminum alloy is 4.3×10-5 mm3·(N·m)-1 at a speed of 0.52 m·s-1 and a load of 40 N.

  16. Improved electrochemical performance of zinc oxide coated lithium manganese silicate electrode for lithium-ion batteries

    Zhu, Jiangtao, E-mail: zhujiangtao1988@163.com [Department of Applied Chemistry, School of Chemical and Engineering, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin (China); Tang, Haoqing [Department of Applied Chemistry, School of Chemical and Engineering, Tianjin University, Tianjin 300072 (China); Tang, Zhiyuan, E-mail: zytang46@163.com [Department of Applied Chemistry, School of Chemical and Engineering, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin (China); Ma, Chenxiang [Department of Applied Chemistry, School of Chemical and Engineering, Tianjin University, Tianjin 300072 (China)

    2015-06-05

    Highlights: • ZnO-coated Li{sub 2}MnSiO{sub 4}/C cathode materials have been successfully prepared via sol–gel method for the first time. • The electrochemical performance of the pure Li{sub 2}MnSiO{sub 4}/C has been significantly improved after coating 1 wt% ZnO. • The better electrochemical performance can be attributed to the improvement of electrochemical kinetics by coating ZnO. - Abstract: ZnO-coated Li{sub 2}MnSiO{sub 4}/C composites have been successfully prepared by a preliminary formation of Li{sub 2}MnSiO{sub 4}/C by facile sol–gel method and a following coating process with ZnO via a wet chemical process. Phase compositions and morphology of the products have been investigated by XRD, SEM, TEM and EDX. The physical characterizations manifest that nano-layer ZnO has been successfully coated on the Li{sub 2}MnSiO{sub 4} particle surface. Among the samples, 1 wt% ZnO coated Li{sub 2}MnSiO{sub 4}/C shows the best performance with an initial discharge capacity of 183 mAh g{sup −1} at 0.1C rate and the specific capacities of 142 and 134 mAh g{sup −1} at the high rate of 0.5C and 1C, respectively, which is much better than Li{sub 2}MnSiO{sub 4}/C without coating ZnO. The better electrochemical performance can be attributed to the significantly decrease of the charge transfer resistance and improvement of lithium ion diffusion coefficient after coating ZnO, which is beneficial for the rapid insertion/extraction of lithium ions.

  17. Improved electrochemical performance of zinc oxide coated lithium manganese silicate electrode for lithium-ion batteries

    Highlights: • ZnO-coated Li2MnSiO4/C cathode materials have been successfully prepared via sol–gel method for the first time. • The electrochemical performance of the pure Li2MnSiO4/C has been significantly improved after coating 1 wt% ZnO. • The better electrochemical performance can be attributed to the improvement of electrochemical kinetics by coating ZnO. - Abstract: ZnO-coated Li2MnSiO4/C composites have been successfully prepared by a preliminary formation of Li2MnSiO4/C by facile sol–gel method and a following coating process with ZnO via a wet chemical process. Phase compositions and morphology of the products have been investigated by XRD, SEM, TEM and EDX. The physical characterizations manifest that nano-layer ZnO has been successfully coated on the Li2MnSiO4 particle surface. Among the samples, 1 wt% ZnO coated Li2MnSiO4/C shows the best performance with an initial discharge capacity of 183 mAh g−1 at 0.1C rate and the specific capacities of 142 and 134 mAh g−1 at the high rate of 0.5C and 1C, respectively, which is much better than Li2MnSiO4/C without coating ZnO. The better electrochemical performance can be attributed to the significantly decrease of the charge transfer resistance and improvement of lithium ion diffusion coefficient after coating ZnO, which is beneficial for the rapid insertion/extraction of lithium ions

  18. Preparation of metal adsorbents from chitin/chitosan by radiation technology

    The methods of preparation of metal adsorbents basing on chitin/chitosan were developed. That include the adsorbent from chitin grafted with acrylic acid by different irradiation doses; the clinging chitosan gel beads; the coagulable solution and the chitosan composite filter. The process of metal adsorption for each adsorbent was studied as adsorption kinetic, isothermal adsorption. The results have been applied for removal of some elements as Hg, Pb, Cd, U, Cu, ect. in the wastewater. (NHA)

  19. Corrosion, ion release and Mott–Schottky probe of chromium oxide coatings in saline solution with potential for orthopaedic implant applications

    Ogwu, A. A.; Oje, A. M.; Kavanagh, J.

    2016-04-01

    We report our investigation on chromium oxide thin film coatings that show a negligible ion release during electrochemical corrosion testing in saline solution. The chemical constituents of the films prepared by reactive magnetron sputtering were identified to be predominantly Cr2O3 based on Raman spectroscopy anti-symmetric stretching vibration modes for CrIII–O and other peaks and an FTIR spectroscopy E u vibrational mode at 409 cm‑1. X-ray photoelectron spectroscopy, multiplet fitting for 2P 3/2 and 2P 1/2 states also confirmed the predominantly Cr2O3 stoichiometry in the films. The prepared chromium oxide coatings showed superior pitting corrosion resistance compared to the native chromium oxide films on bare uncoated stainless steel when tested under open circuit potential, potentiodynamic polarisation and cyclic voltammetry in saline solution. The chromium ion released into solution during the corrosion testing of stainless steel substrates coated with chromium oxide coatings was found to be negligibly small based on atomic absorption spectroscopy measurements. Our Mott–Schottky analysis investigation showed that the negligibly small ion release from the chromium oxide coated steel substrates is most likely due to a much lower defect density on the surface of the deposited coatings compared to the native oxide layer on the uncoated steel substrates. This opens up the opportunity for using chromium oxide surface coatings in hip, knee and other orthopaedic implants where possible metal ion release in vivo still poses a great challenge.

  20. Nano-SiC/SiC anti-oxidant coating on the surface of graphite

    Jafari, H.; Ehsani, N.; Khalifeh-Soltani, S. A.; Jalaly, M.

    2013-01-01

    In this research, a dual-layer coating has been used to improve high temperature oxidation resistance of graphite substrate. For first layer, silicon carbide was applied by pack cementation method. Powder pack consisted of Si, SiC and Al2O3 and heat-treated at 1650 °C in an argon atmosphere. SEM and XRD characterizations confirmed formation of SiC diffusion coating with about 500 μm including compositionally gradient of C and Si elements. Electrophoretic deposition (EPD) was used to deposit nano SiC (SiCn) particles as second layer. Thickness of second layer of SiCn in corresponded optimal situation was 50 μm. Samples with single and dual layers were investigated in oxidation test at 1600 °C. Results showed that an extreme increase was occurred in oxidation resistance after application of second layer of nano SiC. Weight loss value for single layer coating of SiC and dual layer coating of SiCn/SiC after oxidation test for 28 h at 1600 °C were 29 wt.% and 2.4 wt.%, respectively.

  1. The phase and microstructural analysis of protective oxide coatings on molybdenum

    Due to their high sensitivity to oxygen, the use of refractory metals requires an effective protection against oxidation. In the case of molybdenum this is achieved by using a silicon and boron based coating commercially marketed under the trade name SIBOR registered. In the moduction of a SIBOR registered -coating, a mixture of Si, B and C is plasma sprayed in air onto the Mo-surface to be protected and subsequently annealed in hydrogen. Previous investigations have shown that in doing so a stationary coating of Mo-borides and Mo-silicides is formed. However, the exact phase arrangement and composition has until now remained unclear. Energy dispersive X-ray spectroscopy (EDS) in the scanning electron microscope (SEM) is able to analyse the silicides in SIBOR registered, although due to the overlapping of the Mo-and B-spectral partial a clear identification of the borides was not possible. Using a combination of electron back scatter diffraction (EBSD) and wavelength dispersive X-ray spectroscopy (WDS) it is, however, shown that SIBOR registered is made up of a series of sublayers of Mo2B and MoB followed by Mo5Si3 and MoSi2, and that the other phases of the Mo-Si-B ternary system, i.e. Mo3Si and Mo5SiB2(T2), do not occur. Notably, the two borides and the Mo5Si3 exhibit a structure which is polycrystalline in the lateral direction yet normal to the surface forms of only a single layer of crystallites. In contrast, the final MoSi2-layer has a polycrystalline structure both in the lateral and in the normal directions. Furthermore, Mo5Si3 and MoSi2 both exhibit marked textures. (orig.)

  2. Enhanced capacitive performance of TiO₂ nanotubes with molybdenum oxide coating

    Guan, Dongsheng; Gao, Xianfeng; Li, Jianyang; Yuan, Chris, E-mail: cyuan@uwm.edu

    2014-05-01

    Highlights: • MoO₃ was firstly deposited on TiO₂ nanotubes for better supercapacitive behaviors. • Coated TiO₂ nanotubes showed much higher capacitance than pure TiO₂ or MoO₃ films. • Deposition cycles were optimized to gain the best capacitance of MoO₃/TiO₂ hybrids. - Abstract: Alpha-phase MoO₃ is electrochemically deposited on well-aligned TiO₂ nanotubes which are synthesized by anodic oxidation. The morphology, composition and electrochemical behaviors of MoO₃-coated and bare TiO₂ nanotubes are studied. The former deliver greatly higher capacitance than the latter and their performance can be readily optimized by varying MoO₃ deposition cycles. The large areal capacitance of 209.6 mF cm⁻² at a scan rate of 5 mV s⁻¹ is firstly achieved for TiO₂ nanotube array electrode. In addition, the coated TiO₂ nanotubes show significantly more capacitance than a dense MoO₃ film. For example, they exhibit a capacitance up to 74.9 F g⁻¹ at 5 mV s⁻¹ in 1 M KCl solution, while the dense film only shows a capacitance of 32.3 F g⁻¹ under same conditions. Such improvement is found ascribed to MoO₃ with high pseudocapacity and TiO₂ nanotubes with large surface area allowing efficient MoO₃ nanoparticle loading and rapid charge transfer. This nanostructured electrode with features of facile synthesis and excellent performance is believed as a potential candidate for supercapacitor applications.

  3. Krypton retention on solid adsorbents

    Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

  4. Study on silicon oxide coated on silver nanocrystal to enhance fluorescence intensity of rare earth complexes

    Qu, Yan-rong; Lin, Xue-mei; Wang, Ai-ling; Wang, Zhong-xia; Kang, Jie; Chu, Hai-bin, E-mail: binghai99@gmail.com; Zhao, Yong-liang, E-mail: hxzhaoyl@163.com

    2014-10-15

    Twelve kinds of rare earth complexes were synthesized using halo-benzoic acid as anion ligand and Sm{sup 3+} and Dy{sup 3+} as central ions, respectively. The complexes were characterized by elemental analysis, rare earth coordination titration and electrospray ionization mass spectra, from which the compositions of the complexes were confirmed to be RE(p-FBA){sub 3}·H{sub 2}O, RE(p-ClBA){sub 3}·2H{sub 2}O, RE(p-BrBA){sub 3}·H{sub 2}O, RE(o-FBA){sub 3}·2H{sub 2}O, RE(o-ClBA){sub 3}·H{sub 2}O, RE(o-BrBA){sub 3}·H{sub 2}O (RE=Sm{sup 3+}, Dy{sup 3+}). Besides, IR spectra and UV–visible absorption spectroscopy indicated that the carboxyl oxygen atoms of ligands coordinated to the rare earth ions. Moreover, Ag@SiO{sub 2} core–shell nanoparticles (NPs) were prepared via a modified Stöber method. The average diameters of silver cores were typically between 60 nm and 70 nm, and the thicknesses of the SiO{sub 2} shells were around 10 nm, 15 nm and 25 nm, respectively. The influence of Ag@SiO{sub 2} NPs on the luminescence properties of the rare earth complexes showed that the luminescence intensities of rare earth complexes were enhanced remarkably. As the thickness of SiO{sub 2} shell increases in the range of 10–25 nm, the effect of metal-enhanced fluorescence become obvious. The mechanism of the changes of the fluorescence intensity is also discussed. - Highlights: • Among 10–25 nm, the thicker the shell thickness, the better the fluorescence effect. • The strong the intensity of the pure complexes, the smaller the multiple enhanced. • The intensity of Sm(p-BrBA){sub 3}·H{sub 2}O is the strongest among Sm(p-XBA){sub 3}·nH{sub 2}O complexes. • The intensity of Dy(p-ClBA){sub 3}·2H{sub 2}O is the strongest among Dy(p-XBA){sub 3}·nH{sub 2}O complexes. • When halogen is in o-position, the intensity of RE(o-ClBA){sub 3}·H{sub 2}O is the strongest.

  5. Nano-Structured Magnesium Oxide Coated Iron Ore: Its Application to the Remediation of Wastewater Containing Lead.

    Nagarajah, Ranjini; Jang, Min; Pichiah, Saravanan; Cho, Jongman; Snyder, Shane A

    2015-12-01

    Magnetically separable nano-structured magnesium oxide coated iron ore (IO(MgO)) was prepared using environmentally benign chemicals, such as iron ore (IO), magnesium(II) nitrate hexahydrate [Mg(NO3)2 x 6H2O] and urea; via an easy and fast preparation method. The lO(MgO) was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and alternating gradient magnetometer (AGM) analyses. The isotherm and kinetic studies indicated that lO(MgO) has a comparably higher Langmuir constant (K(L), 1.69 L mg(-1)) and maximum sorption capacity (33.9 mg g(-1)) for lead (Pb) than other inorganic media. Based on MgO amount, the removal capacity of Pb by IO(MgO) was 2,724 mg Pb (g MgO)(-1), which was higher than that (1,980 mg g(-1)) for flowerlike magnesium oxide nanostructures reported by Cao et al. The kinetics, FE-SEM, elemental mapping and XRD results revealed that the substitution followed by precipitation was identified as the mechanism of Pb removal and plumbophyllite (Pb2Si4O10 x H2O) was the precipitated phase of Pb. A leaching test revealed that IOMgO) had negligible concentrations of leached Fe at pH 4-9. Since the base material, IO, is cheap and easily available, lO(MgO) could be produced in massive amounts and used for remediation of wastewater containing heavy metals, applying simple and fast magnetic separation. PMID:26682385

  6. Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

    Norris, M J; Pulford, I D; Haynes, H; Dorea, C C; Phoenix, V R

    2013-01-01

    Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS. PMID:23925197

  7. Growth and characterization of chromium oxide coatings prepared by pulsed-direct current reactive unbalanced magnetron sputtering

    Approximately 0.2-3.2 μm thick single phase chromium oxide (Cr2O3) coatings with different oxygen flow rates were deposited on silicon and mild steel substrates at low substrate temperature (∼60 deg. C) by pulsed-direct current (DC) reactive unbalanced magnetron sputtering. Two asymmetric bipolar-pulsed DC generators were used to co-sputter two Cr targets, in Ar + O2 plasma. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation hardness tester, optical microscopy, atomic force microscopy, micro-Raman spectroscopy, spectroscopic ellipsometry and potentiodynamic polarization techniques. The XRD data showed the presence of mixture of crystalline (rhombohedral Cr2O3) and amorphous phases for the coatings prepared with oxygen flow rate less than 10 sccm. A complete transformation to amorphous phase was observed at higher oxygen flow rates. The XRD results were supported by Raman spectroscopy data. The XPS data suggested that the chemical state of Cr was in the form of Cr3+. The chromium oxide coatings exhibited a maximum hardness of 22 GPa and an elastic modulus of 208 GPa. The coatings exhibited high thermal stability upon annealing in vacuum up to 500 deg. C and retained hardness as high as 17 GPa. Spectroscopic ellipsometry data indicated that coatings prepared at higher oxygen flow rates were dielectric in nature and those prepared at low oxygen flow rates exhibited an intermediate character, i.e., a transition between the dielectric and the metallic behavior. The corrosion behavior of Cr2O3 coating deposited on mild steel substrates was investigated using potentiodynamic polarization in 3.5% NaCl solution. The results indicated that Cr2O3 coating exhibited superior corrosion resistance as compared to the uncoated substrate

  8. Growth and characterization of chromium oxide coatings prepared by pulsed-direct current reactive unbalanced magnetron sputtering

    Barshilia, Harish C.; Rajam, K. S.

    2008-12-01

    Approximately 0.2-3.2 μm thick single phase chromium oxide (Cr 2O 3) coatings with different oxygen flow rates were deposited on silicon and mild steel substrates at low substrate temperature (˜60 °C) by pulsed-direct current (DC) reactive unbalanced magnetron sputtering. Two asymmetric bipolar-pulsed DC generators were used to co-sputter two Cr targets, in Ar + O 2 plasma. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation hardness tester, optical microscopy, atomic force microscopy, micro-Raman spectroscopy, spectroscopic ellipsometry and potentiodynamic polarization techniques. The XRD data showed the presence of mixture of crystalline (rhombohedral Cr 2O 3) and amorphous phases for the coatings prepared with oxygen flow rate less than 10 sccm. A complete transformation to amorphous phase was observed at higher oxygen flow rates. The XRD results were supported by Raman spectroscopy data. The XPS data suggested that the chemical state of Cr was in the form of Cr 3+. The chromium oxide coatings exhibited a maximum hardness of 22 GPa and an elastic modulus of 208 GPa. The coatings exhibited high thermal stability upon annealing in vacuum up to 500 °C and retained hardness as high as 17 GPa. Spectroscopic ellipsometry data indicated that coatings prepared at higher oxygen flow rates were dielectric in nature and those prepared at low oxygen flow rates exhibited an intermediate character, i.e., a transition between the dielectric and the metallic behavior. The corrosion behavior of Cr 2O 3 coating deposited on mild steel substrates was investigated using potentiodynamic polarization in 3.5% NaCl solution. The results indicated that Cr 2O 3 coating exhibited superior corrosion resistance as compared to the uncoated substrate.

  9. Growth and characterization of chromium oxide coatings prepared by pulsed-direct current reactive unbalanced magnetron sputtering

    Barshilia, Harish C. [Surface Engineering Division, National Aerospace Laboratories, Post Bag No. 1779, Kodihalli Airport Road, Bangalore 560017 (India)], E-mail: harish@css.nal.res.in; Rajam, K.S. [Surface Engineering Division, National Aerospace Laboratories, Post Bag No. 1779, Kodihalli Airport Road, Bangalore 560017 (India)

    2008-12-30

    Approximately 0.2-3.2 {mu}m thick single phase chromium oxide (Cr{sub 2}O{sub 3}) coatings with different oxygen flow rates were deposited on silicon and mild steel substrates at low substrate temperature ({approx}60 deg. C) by pulsed-direct current (DC) reactive unbalanced magnetron sputtering. Two asymmetric bipolar-pulsed DC generators were used to co-sputter two Cr targets, in Ar + O{sub 2} plasma. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation hardness tester, optical microscopy, atomic force microscopy, micro-Raman spectroscopy, spectroscopic ellipsometry and potentiodynamic polarization techniques. The XRD data showed the presence of mixture of crystalline (rhombohedral Cr{sub 2}O{sub 3}) and amorphous phases for the coatings prepared with oxygen flow rate less than 10 sccm. A complete transformation to amorphous phase was observed at higher oxygen flow rates. The XRD results were supported by Raman spectroscopy data. The XPS data suggested that the chemical state of Cr was in the form of Cr{sup 3+}. The chromium oxide coatings exhibited a maximum hardness of 22 GPa and an elastic modulus of 208 GPa. The coatings exhibited high thermal stability upon annealing in vacuum up to 500 deg. C and retained hardness as high as 17 GPa. Spectroscopic ellipsometry data indicated that coatings prepared at higher oxygen flow rates were dielectric in nature and those prepared at low oxygen flow rates exhibited an intermediate character, i.e., a transition between the dielectric and the metallic behavior. The corrosion behavior of Cr{sub 2}O{sub 3} coating deposited on mild steel substrates was investigated using potentiodynamic polarization in 3.5% NaCl solution. The results indicated that Cr{sub 2}O{sub 3} coating exhibited superior corrosion resistance as compared to the uncoated substrate.

  10. Validation of In-Situ Iron-Manganese Oxide Coated Stream Pebbles as Sensors for Arsenic Source Monitoring

    Blake, J.; Peters, S. C.; Casteel, A.

    2013-12-01

    Locating nonpoint source contaminant fluxes can be challenging due to the inherent heterogeneity of source and of the subsurface. Contaminants such as arsenic are a concern for drinking water quality and ecosystem health. Arsenic contamination can be the result of several natural and anthropogenic sources, and therefore it can be difficult to trace and identify major areas of arsenic in natural systems. Identifying a useful source indicator for arsenic is a crucial step for environmental remediation efforts. Previous studies have found iron-manganese oxide coated streambed pebbles as useful source indicators due to their high attraction for heavy metals in water. In this study, pebbles, surface water at baseflow and nearby rocks were sampled from the Pennypack Creek and its tributaries, in southwestern Pennsylvania, to test the ability of coated streambed pebbles as environmental source indicators for arsenic. Quartz pebbles, 5-7 cm in diameter, were sampled to minimize elemental contamination from rock chemistry. In addition, quartz provides an excellent substrate for iron and manganese coatings to form. These coatings were leached from pebbles using 4M nitric acid with 0.1% concentrated hydrochloric acid. Following sample processing, analyses were performed using an ICP-MS and the resulting data were spatially organized using ArcGIS software. Arsenic, iron and manganese concentrations in the leachate are normalized to pebble surface area and each location is reported as a ratio of arsenic to iron and manganese. Results suggest that iron-manganese coated stream pebbles are useful indicators of arsenic location within a watershed.

  11. Influence of oxygen ion irradiation on the corrosion aspects of Ti-5%Ta-2%Nb alloy and oxide coated titanium

    The corrosion resistance of Ti-5%Ta-2%Nb alloy and DOCTOR (double oxide coating on titanium for reconditioning) coated titanium by O5+ ion irradiation were compared and investigated for their corrosion behaviour. O5+ ion irradiations were carried out at a dose rate of 1 x 1017, 1 x 1018 and 1 x 1019 ions/m2 at 116 MeV. The surface properties and corrosion resistance were evaluated by using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), glancing-angle X-ray diffraction (GXRD) and electrochemical testing methods. The results of electrochemical investigations in 11.5 N HNO3 indicated that the open circuit potential (OCP) of DOCTOR coated titanium is nobler than Ti-5%Ta-2%Nb alloy. The potentiodynamic polarization study of Ti-5%Ta-2%Nb alloy and DOCTOR coated specimen indicated decrease in passive current density with increase in ion doses (1 x 1017 to 1 x 1019 ions/m2) indicating decrease in anodic dissolution. Nyquist arc behaviour in the electrochemical impedance study substantiated the enhancement in oxide layer stability by O5+ ion irradiation. AFM results revealed that the DOCTOR coated Ti surface was dense without gross voids, and the surface roughness decreased by O5+ ion irradiation, but increased after corrosion test. EDX and GXRD patterns of DOCTOR coated Ti sample indicated that the coating was mainly composed of rutile TiO2. Based on the above results, the O5+ ion irradiation effect on corrosion behavior of Ti-5%Ta-2%Nb alloy and DOCTOR coated titanium are discussed in this paper

  12. Influence of C3H8O3 in the electrolyte on characteristics and corrosion resistance of the microarc oxidation coatings formed on AZ91D magnesium alloy surface

    Ceramic coatings were fabricated on AZ91D Mg-alloy substrate by microarc oxidation in Na2SiO3-NaOH-Na2EDTA electrolytes with and without C3H8O3 addition. The effects of different concentrations of C3H8O3 contained in the electrolyte on coatings thickness were investigated. The surface morphologies, RMS roughness, phase compositions and corrosion resistance property of the ceramic coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrochemical corrosion test respectively. It is found that the addition of C3H8O3 into silicate electrolyte leads to increase of the unit-area adsorptive capacity of the negative ions at anode-electrolyte interface and thus improves the compactness and corrosion resistance of the MAO coating. The coating thickness decreases gradually with the increase of concentrations of C3H8O3 in the electrolyte. The oxide coating formed in base electrolyte containing 4 mL/L C3H8O3 exhibits the best surface appearance, the lowest surface RMS roughness (174 nm) and highest corrosion resistance. In addition, both ceramic coatings treated in base electrolyte with and without C3H8O3 are mainly composed of periclase MgO and forsterite Mg2SiO4 phase, but no diffraction peak of Mg phase is found in the patterns.

  13. Lotus Dust Mitigation Coating and Molecular Adsorber Coating

    O'Connor, Kenneth M.; Abraham, Nithin S.

    2015-01-01

    NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

  14. Thermodynamic and kinetic controls on cotransport of Pantoea agglomerans cells and Zn through clean and iron oxide coated sand columns

    Kapetas, Leon; Ngwenya, Bryne T; MacDonald, Alan; Elphick, Stephen C.

    2012-01-01

    Recent observations that subsurface bacteria quickly adsorb metal contaminants raise concerns that they may enhance metal transport, given the high mobility of bacteria themselves. However, metal adsorption to bacteria is also reversible, suggesting that mobility within porous medium will depend on the interplay between adsorption desorption kinetics and thermodynamic driving forces for adsorption. Till now there has been no systematic investigation of these important interactions. This st...

  15. Study of the Adsorbent-Adsorbate Interactions from Cd(II) and Pb(II) Adsorption on Activated Carbon and Activated Carbon Fiber

    The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents

  16. The effects of argon pre-annealing on the superconductive properties of plasma-sprayed Y-Ba-Cu-oxide coatings

    Plasma spraying is a deposition method with the potential of producing large quantities of high temperature superconductive coatings. The as-sprayed Y-Ba-Cu-oxide coatings are mostly the substitution tetragonal phase, YBa2-xYxCu3Oy. Oxygen-annealing of this phase below 960 degree C results in a poorly-superconducting orthorhombic phase. However, this study shows that the superconducting properties can be improved by annealing the as-sprayed coatings in an argon atmosphere at 850 degree C prior to the oxygen annealing

  17. Protein purification using magnetic adsorbent particles

    Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John;

    2006-01-01

    The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence...

  18. Black Sprayable Molecular Adsorber Coating Project

    National Aeronautics and Space Administration — This novel molecular adsorber coating would alleviate the size, weight, and complexity issues of traditional molecular adsorber puck.  A flexible tape version...

  19. Magneto-controllable capture and release of cancer cells by using a micropillar device decorated with graphite oxide-coated magnetic nanoparticles.

    Yu, Xiaolei; He, Rongxiang; Li, Shasha; Cai, Bo; Zhao, Libo; Liao, Lei; Liu, Wei; Zeng, Qian; Wang, Hao; Guo, Shi-Shang; Zhao, Xing-Zhong

    2013-11-25

    Aiming to highly efficient capture and analysis of circulating tumor cells, a micropillar device decorated with graphite oxide-coated magnetic nanoparticles is developed for magneto-controllable capture and release of cancer cells. Graphite oxide-coated, Fe3 O4 magnetic nanoparticles (MNPs) are synthesized by solution mixing and functionalized with a specific antibody, following by the immobilization of such modified MNPs on our designed micropillar device. For the proof-of-concept study, a HCT116 colorectal cancer cell line is employed to exam the capture efficiency. Under magnetic field manipulation, the high density packing of antibody-modified MNPs on the micropillars increases the local concentration of antibody, as well as the topographic interactions between cancer cells and micropillar surfaces. The flow rate and the micropillar geometry are optimized by studying their effects on capture efficiency. Then, a different number of HCT116 cells spiked in two kinds of cell suspension are investigated, yielding capture efficiency >70% in culture medium and >40% in blood sample, respectively. Moreover, the captured HCT116 cells are able to be released from the micropillars with a saturated efficiency of 92.9% upon the removal of applied magnetic field and it is found that 78% of the released cancer cells are viable, making them suitable for subsequent biological analysis. PMID:23650272

  20. 石英砂负载氧化铁吸附去除溶液中亚甲蓝的研究%Removal of methylene blue in solution by iron-oxide coated quartz sand

    宣寒; 谢发之; 王颖; 曹田; 陈艳; 陈方平

    2013-01-01

    Using quartz sand as raw material,iron oxide coated quartz sand(IOCS) has been prepared.IOCS performance and the effect of adsorption conditions on the adsorption capacity for methylene blue and the regeneration of adsorptive column are investigated.The adsorption course has been studied kinetically.The results show that the IOCS prepared by high temperature sintering method has better adsorption capacity for methylene blue.The optimal conditions for IOCS to adsorb the methylene blue in solution are as follows:pH is 13.5,mass concentration of methylene blue about 6 mg/L,temperature 293 K,and adsorptive sample flow velocity 4 BV/h.The curve of adsorptive kinetics of methylene blue in solution can be fitted with Weber-Morris curve.Langmuir and Freundlich adsorption isotherm equations can well describe the adsorption course of methylene blue in solution by IOCS.The regeneration efficacy of IOCS adsorptive column by using 0.01 mol/L of HCl is pretty good.%以石英砂为原料制得石英砂负载氧化铁(IOCS),考察了IOCS的性能、吸附条件对IOCS吸附亚甲蓝效果的影响及吸附柱的再生,并对吸附过程进行了动力学研究.结果表明,采用高温烧结法制备的IOCS吸附亚甲蓝效果较好;IOCS对溶液中亚甲蓝吸附的适宜条件:pH为13.5,亚甲蓝质量浓度约为6mg/L,温度为293 K,上样液吸附流速为4 BV/h; IOCS对溶液中亚甲蓝的吸附动力学曲线可以用Weber-Morris曲线来拟合;Langmuir吸附等温方程和Freundlich方程都能较好地描述IOCS对溶液中亚甲蓝的吸附过程;0.01 mol/L的HCl对IOCS吸附柱的再生效果较好.

  1. pyIAST: Ideal adsorbed solution theory (IAST) Python package

    Simon, Cory M.; Smit, Berend; Haranczyk, Maciej

    2016-03-01

    Ideal adsorbed solution theory (IAST) is a widely-used thermodynamic framework to readily predict mixed-gas adsorption isotherms from a set of pure-component adsorption isotherms. We present an open-source, user-friendly Python package, pyIAST, to perform IAST calculations for an arbitrary number of components. pyIAST supports several common analytical models to characterize the pure-component isotherms from experimental or simulated data. Alternatively, pyIAST can use numerical quadrature to compute the spreading pressure for IAST calculations by interpolating the pure-component isotherm data. pyIAST can also perform reverse IAST calculations, where one seeks the required gas phase composition to yield a desired adsorbed phase composition.

  2. Composites

    Zhao, Hanqing; Guo, Yuanzheng

    2014-01-01

    This thesis was a literature study concerning composites. With composites becoming increasingly popular in various areas such as aerospace industry and construction, the research about composites has a significant meaning accordingly. This thesis was aim at introducing some basic information of polymer matrix composites including raw mate-rial, processing, testing, applications and recycling to make a rough understanding of this kind of material for readers. Polymeric matrices, fillers,...

  3. Composition

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  4. Composition

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  5. Composition

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  6. Composition

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all...

  7. Enhanced encapsulation of metoprolol tartrate with carbon nanotubes as adsorbent

    Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Dharamsi, Abhay

    2011-12-01

    A highly water-soluble antihypertensive drug, metoprolol tartrate (MT), was selected as a model drug for preparation of multi-walled carbon nanotubes (MWCNTs)-impregnated ethyl cellulose (EC) microspheres. The present investigation was aimed to increase encapsulation efficiency of MT with excellent adsorbent properties of MWCNTs. The unique surface area, stiffness, strength and resilience of MWCNTs have drawn much anticipation as carrier for highly water-soluble drugs. Carbon nanotubes drug adsorbate (MWCNTs:MT)-loaded EC microspheres were further optimized by the central composite design of the experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and t 50 (time required for 50% drug release). The optimized batch was compared with drug alone EC microspheres. The results revealed high degree of improvement in encapsulation efficiency for MWCNTs:MT-loaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 15 h, while by the same time only 50-60% drug was released for MWCNTs-impregnated EC microspheres. The optimized batch was further characterized by various instrumental analyses such as scanning electron microscopy, powder X-ray diffraction and differential scanning calorimetry. The results endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres, which might have resulted in enhanced encapsulation and sustained effect of MT. Hence, MWCNTs can be utilized as novel carriers for extended drug release and enhanced encapsulation of highly water-soluble drug, MT.

  8. Dissolved Air Flotation of arsenic adsorbent particles

    Santander, M.; Valderrama, L.

    2015-01-01

    The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF) and dissolved air flotation (DAF). A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic polyacrylamide (NALCO 9808) as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with fl...

  9. A novel fiber-based adsorbent technology

    Reynolds, T.A. [Chemica Technologies, Inc., Bend, OR (United States)

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  10. Thickness effects on corrosion and wear resistance properties of micro-arc discharge oxide coatings on AZ91D magnesium alloys

    HUANG Wei-jiu; LIU Ming; LI Zhao-feng; ZENG Rong-chang

    2006-01-01

    The microarc oxidation coatings with difference thickness were synthesized on AZ91D magnesium alloy. The microstructure and phase structure of the coatings were analyzed using SEM and XRD, the tribological properties and corrosion resistance behaviour of the coatings were also investigated. The results show that the coating contains two layers, a porous outer layer and relatively dense inner layer. The microhardness of the MAO coatings is four to six times higher than that of the magnesium alloy substrate. The MAO coatings have much better wear-resistance and corrosion resistance abilities than those of magnesium alloy substrate, but possess higher friction coefficient. The results further indicate that there is an optimization thickness for corrosion and wear resistance.

  11. Filter-adsorber aging assessment

    An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission's (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period

  12. Microporous carbonaceous adsorbents for CO2 separation via selective adsorption

    Zhao, Yunfeng

    2015-01-01

    Selective adsorption of CO2 has important implications for many energy and environment-related processes, which require the separation of CO2 from other gases (e.g. N2 and CH4) with high uptakes and selectivity. The development of high-performance adsorbents is one of the most promising solutions to the success of these processes. The present review is focused on the state-of-the-art of carbon-based (carbonaceous) adsorbents, covering microporous inorganic carbons and microporous organic polymers, with emphasis on the correlation between their textural and compositional properties and their CO2 adsorption/separation performance. Special attention is given to the most recently developed materials that were not covered in previous reviews. We summarize various effective strategies (N-doping, surface functionalization, extra-framework ions, molecular design, and pore size engineering) for enhancing the CO2 adsorption capacity and selectivity of carbonaceous adsorbents. Our discussion focuses on CO2/N2 separation and CO2/CH4 separation, while including an introduction to the methods and criteria used for evaluating the performance of the adsorbents. Critical issues and challenges regarding the development of high-performance adsorbents as well as some overlooked facts and misconceptions are also discussed, with the aim of providing important insights into the design of novel carbonaceous porous materials for various selective adsorption based applications. This journal is © The Royal Society of Chemistry.

  13. Scanning tunneling microscopy theory for an adsorbate: Application to adenine adsorbed on a graphite surface

    Ou-Yang, Hui; Marcus, R. A.; Källebring, Bruno

    1994-01-01

    An expression is obtained for the current in scanning tunneling microscopy (STM) for a single adsorbate molecule. For this purpose the ``Newns–Anderson'' treatment (a ``discrete state in a continuum'' treatment) is used to obtain wave functions and other properties of the adsorbate/substrate system. The current is expressed in terms of the adsorbate–tip matrix elements, and an effective local density of states of the adsorbate/substrate system, at the adsorbate. As an example, the treatment i...

  14. Ecological applications of the irradiated adsorbents

    Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.γ) - radiation, α-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

  15. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  16. A theoretical study of adsorbate-adsorbate interactions on Ru(0001)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using density functional theory we study the effect of pre-adsorbed atoms on the dissociation of N(2) and the adsorption of N, N(2), and CO on Ru(0001). We have done calculations for pre-adsorbed Na, Cs, and S, and find that alkali atoms adsorbed close to a dissociating N(2) molecule will lower t...

  17. Extra adsorption and adsorbate superlattice formation in metal-organic frameworks

    Sung Cho, Hae; Deng, Hexiang; Miyasaka, Keiichi; Dong, Zhiyue; Cho, Minhyung; Neimark, Alexander V.; Ku Kang, Jeung; Yaghi, Omar M.; Terasaki, Osamu

    2015-11-01

    Metal-organic frameworks (MOFs) have a high internal surface area and widely tunable composition, which make them useful for applications involving adsorption, such as hydrogen, methane or carbon dioxide storage. The selectivity and uptake capacity of the adsorption process are determined by interactions involving the adsorbates and their porous host materials. But, although the interactions of adsorbate molecules with the internal MOF surface and also amongst themselves within individual pores have been extensively studied, adsorbate-adsorbate interactions across pore walls have not been explored. Here we show that local strain in the MOF, induced by pore filling, can give rise to collective and long-range adsorbate-adsorbate interactions and the formation of adsorbate superlattices that extend beyond an original MOF unit cell. Specifically, we use in situ small-angle X-ray scattering to track and map the distribution and ordering of adsorbate molecules in five members of the mesoporous MOF-74 series along entire adsorption-desorption isotherms. We find in all cases that the capillary condensation that fills the pores gives rise to the formation of ‘extra adsorption domains’—that is, domains spanning several neighbouring pores, which have a higher adsorbate density than non-domain pores. In the case of one MOF, IRMOF-74-V-hex, these domains form a superlattice structure that is difficult to reconcile with the prevailing view of pore-filling as a stochastic process. The visualization of the adsorption process provided by our data, with clear evidence for initial adsorbate aggregation in distinct domains and ordering before an even distribution is finally reached, should help to improve our understanding of this process and may thereby improve our ability to exploit it practically.

  18. Fluorescence dynamics of microsphere-adsorbed sunscreens

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  19. NOx adsorber and method of regenerating same

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  20. Nanovalved Adsorbents for CH4 Storage.

    Song, Zhuonan; Nambo, Apolo; Tate, Kirby L; Bao, Ainan; Zhu, Minqi; Jasinski, Jacek B; Zhou, Shaojun J; Meyer, Howard S; Carreon, Moises A; Li, Shiguang; Yu, Miao

    2016-05-11

    A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications. PMID:27124722

  1. Inorganic chemically active adsorbents (ICAAs)

    Ally, M.R. [Oak Ridge National Lab., TN (United States); Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  2. CuO embedded chitosan spheres as antibacterial adsorbent for dyes.

    Khan, Sher Bahadar; Ali, Fayaz; Kamal, Tahseen; Anwar, Yasir; Asiri, Abdullah M; Seo, Jongchul

    2016-07-01

    Chitosan/copper oxide (CS/CuO) composite spheres were prepared by simple mixing of CuO nanomaterials in CS solution followed by dropwise addition to NH4OH solution. The characterizations of all the prepared spheres were carried out by FESEM, EDS, XRD, XPS, and FTIR analyses while the thermal properties were analyzed by TGA. Further the ability of composite spheres was tested as an easily removable pollutant adsorbent from water containing different dyes and compared with pure CS. Composite spheres were found to be the best adsorbent when applied to remove indigo carmine (IC), congo red (CR) and methyl orange (MO) from water. Amongst the three dyes, CS/CuO composite spheres were more selective toward MO adsorption. CS/CuO composite spheres also displayed significant antibacterial activity by inhibiting Pseudomonas aeruginosa growth. Thus the fabricated composite spheres can be used as a biosorbent in the future. PMID:26993528

  3. Synthesis and performance evaluation of Al/Fe oxide coated diatomaceous earth in groundwater defluoridation: Towards fluorosis mitigation.

    Izuagie, Anthony A; Gitari, Wilson M; Gumbo, Jabulani R

    2016-08-23

    The quest to reduce fluoride in groundwater to WHO acceptable limit of 1.5 mg/L to prevent diseases such as teeth mottling and skeletal fluorosis was the motivation for this study. Al/Fe oxide-modified diatomaceous earth was prepared and its defluoridation potential evaluated by batch method. The sorbent with pHpzc 6.0 ± 0.2 is very reactive. The maximum 82.3% fluoride removal attained in 50 min using a dosage of 0.3 g/100 mL in 10 mg/L fluoride was almost attained within 5 min contact time; 81.3% being the percent fluoride removal at 5 min contact time. The sorbent has a usage advantage of not requiring solution pH adjustment before it can exhibit its fluoride removal potential. A substantial amount of fluoride (93.1%) was removed from solution when a sorbent dosage of 0.6 g/100 mL was contacted with 10 mg/L fluoride solution for 50 min at a mixing rate of 200 rpm. The optimum adsorption capacity of the adsorbent was 7.633 mg/g using a solution containing initially 100 mg/L fluoride. The equilibrium pH of the suspensions ranged between 6.77 and 8.26 for 10 and 100 mg/L fluoride solutions respectively. Contacting the sorbent at a dosage of 0.6 g/100 mL with field water containing 5.53 mg/L at 200 rpm for 50 min reduced the fluoride content to 0.928 mg/L-a value below the upper limit of WHO guideline of 1.5 mg/L fluoride in drinking water. The sorption data fitted to both Langmuir and Freundlich isotherms but better with the former. The sorption data obeyed only the pseudo-second-order kinetic, which implies that fluoride was chemisorbed. PMID:27220558

  4. Influence of frequency on the structure of zirconium oxide coatings deposited from aqueous electrolytes under microplasma oxidation

    The work describes the microplasma oxidation (MPO) of zirconium surface resulting in the formation of zirconium oxide Zr-Al-Nb-O. We have used novel power supply to deposit oxide ceramic coatings by MPO and studied the effect of current density on the phase structure of oxide ceramic coatings. The size of microcracks in the coatings was determined at different frequencies. We have also used EVO50c scanning election microscope with an attachment for elemental analysis to study the morphology and elemental composition of oxide ceramic coating. In addition, we have established the influence of the frequency on the phase composition of the coating: at the frequency of 2500 Hz, the fraction of monoclinic phase was 18%, while the fraction of tetragonal phase amounted to 72%. The oxide ceramic coating produced at 250 Hz contained 38% of monoclinic phase and 62% of tetragonal phase; in addition, it had no buildups and craters

  5. Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium.

    Hu, Baiyang; Fugetsu, Bunshi; Yu, Hongwen; Abe, Yoshiteru

    2012-05-30

    We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent. PMID:22464752

  6. Effects of Surface Coating Preparation and Sliding Modes on Titanium Oxide Coated Titanium Alloy for Aerospace Applications

    Bo Yuan Peng; Xueyuan Nie; Ying Chen

    2014-01-01

    This paper investigates the mechanical response of a coated Ti-6Al-4V alloy surface under different sliding contact stress conditions. The surface was coated with an oxide ceramic material created through the use of a recently developed technique known as plasma electrolytic oxidation (PEO). During the PEO procedure, a composition of silicate and phosphate was used as the electrolyte. In order to evaluate the coating, pin-on-disk (POD) tribology tests and cyclic inclined sliding tests were us...

  7. Characterization of adsorbed dicarbonyls of rhodium

    We have studies the adsorbed states of CO on dispersed RH in Y zeolites by solid-state 13C NMR spectroscopy. The structure of the dicarbonyl form of adsorbed rhodium has been revealed using a Carr-Purcell-Meiboom-Gill multiple pulse sequence. NMR lineshape calculations show that adsorbed Rh(CO)2 species are undergoing a 180 deg. flipping motion about the C2 axis which bisects the C-Rh-C angle. Spectra calculated with this motional model have been compared with published spectra of CO on Rh-Y zeolites. (author). 7 refs.; 3 figs

  8. States of water adsorbed on perindopril crystals

    Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

    2011-10-01

    The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

  9. New liquid waste control with tannin adsorbent

    Since 1971, the Mitsubishi Nuclear Fuel Co., Ltd. (MNF) has been fabricating PWR fuels and developing related technology and processes. In the UF6 reconversion lines of MNF, the ammonium diuranate (ADU) process has been operating and the newly developed process of liquid waste treatment was installed last year. The characteristic of this process is to use insoluble tannin adsorbent which has been developed by MNF. The tannin adsorbent is not only an effective means to adsorb heavy metals such as uranium and plutonium but is also easy to incinerate at low temperature. Control of radioactive liquid waste from nuclear facilities is generally implemented by co-precipitation. However, it produces secondary wastes such as noncombustible materials which include radionuclides and it is anticipated that the storage and disposal of those wastes will be at high cost. Those are the reasons why tannin adsorbent has an advantage, and why MNF develops it. (author)

  10. Synthesis of Micro/Mesoporous Composites and Their Application as CO2 Adsorbents%微孔/介孔复合分子筛的合成及其对CO2的吸附性能

    马燕辉; 赵会玲; 唐圣杰; 胡军; 刘洪来

    2011-01-01

    采用两步晶化法将合成的沸石前驱液(S)或沸石固体粉末(P)经不同浓度(c)的NaOH处理后,分别以表面活性剂十六烷基三甲基溴化铵(CTAB)软模板或介孔炭(aeso-C)硬模板为导向剂,自组装合成S-β-MCM41(c)、P-β-MCM41(c)、P-ZSM-MCM41(c)、P-ZSM-C系列微孔,介孔复合分子筛.考察了沸石分子筛种类、碱处理液浓度以及介孔模板剂对合成复合分子筛结构与性能的影响.X射线衍射(XRD)、透射电子显微镜(TEM)和氮气吸附-脱附表征结果表明产物具有微孔/介孔多级孔结构.该材料对CO2的吸附能力比纯微孔或介孔材料均有明显提高,其中P-ZSM-MCM41(2)的CO2吸附容量最大可达1.51 mmol·g-1,为ZSM-5沸石吸附量的两倍多.%We synthesized a series of micro/mesoporous composites of S-β-MCM41(c), P-β-MCM41(c),P-ZSM-MCM41(c), P-ZSM-C through a two-step crystallization process. During this process, the microporous zeolite precursor solution (S) or the zeolite powder (P) was first synthesized and treated with NaOH solution with different concentration (c), and then the mesopores were induced by hexadecyltrimethyl-ammoniumbromide (CTAB) as a soft template or mesoporous carbon as a hard template. The effects of the type of inorganic precursor, the base concentration, and the type of mesoporous template on the structure and property of the micro/mesoporous composites were investigated. The results of X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms showed that the products contained micropores and mesopores, simultaneously. The CO2 adsorption capacities of these micro/mesoporous composites were obviously improved compared to the pure microporous or mesoporous materials. Among them, P-ZSM-MCM41(2) had the highest CO2 adsorption capacity of 1.51 mmol·g-1, which was almost twice that of the original ZSM-5.

  11. Binder-free graphene and manganese oxide coated carbon felt anode for high-performance microbial fuel cell.

    Zhang, Changyong; Liang, Peng; Yang, Xufei; Jiang, Yong; Bian, Yanhong; Chen, Chengmeng; Zhang, Xiaoyuan; Huang, Xia

    2016-07-15

    A novel anode was developed by coating reduced graphene oxide (rGO) and manganese oxide (MnO2) composite on the carbon felt (CF) surface. With a large surface area and excellent electrical conductivity, this binder-free anode was found to effectively enhance the enrichment and growth of electrochemically active bacteria and facilitate the extracellular electron transfer from the bacteria to the anode. A microbial fuel cell (MFC) equipped with the rGO/MnO2/CF anode delivered a maximum power density of 2065mWm(-2), 154% higher than that with a bare CF anode. The internal resistance of the MFC with this novel anode was 79Ω, 66% lower than the regular one's (234Ω). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses affirmed that the rGO/MnO2 composite significantly increased the anodic reaction rates and facilitated the electron transfer from the bacteria to the anode. The findings from this study suggest that the rGO/MnO2/CF anode, fabricated via a simple dip-coating and electro-deposition process, could be a promising anode material for high-performance MFC applications. PMID:26918615

  12. Properties and selection criteria for adsorbents

    The paper gives a survey of the most important industrial adsorbents and of their suitability for different purposes. With special consideration of activated carbon, the properties and characteristic data are discussed which are used for assessing adsorbents. These, among other things, are as follows: specific surface area, pore size distribution, adsorption isotherms, hydrophobic properties, catalytic properties, chemical resistance, heat resistance, particle size and hardness. (orig.)

  13. Dissolved Air Flotation of arsenic adsorbent particles

    M. Santander

    2015-04-01

    Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic polyacrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

  14. Membrane Perturbation Induced by Interfacially Adsorbed Peptides

    Zemel, Assaf; Ben-Shaul, Avinoam; May, Sylvio

    2004-01-01

    The structural and energetic characteristics of the interaction between interfacially adsorbed (partially inserted) α-helical, amphipathic peptides and the lipid bilayer substrate are studied using a molecular level theory of lipid chain packing in membranes. The peptides are modeled as “amphipathic cylinders” characterized by a well-defined polar angle. Assuming two-dimensional nematic order of the adsorbed peptides, the membrane perturbation free energy is evaluated using a cell-like model;...

  15. Behavior of macromolecules in adsorbed layers

    2000-01-01

    A model for describing the behavior of macromolecules in adsorbed layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics. The molecular behavior of layers adsorbed on clay particle surfaces is discussed; the random distribution and its statistics of the layer thickness are given by incorporating experimental results with an ionic polyelectrolyte with the molecular weight of 1.08×106 and chain charged density of 0.254.

  16. ADSORBENTS USED IN THE CLEARANCE OF ENDOTOXIN

    YU Mei; LIU Tao; Hou Guanghui; YUAN Zhi

    2003-01-01

    A series of modified poly (methyl methacrylate, PMMA) resins were prepared and compared their adsorption abilities to endotoxin. The results showed that adsorbents, which were grafted with tertiary amine and long spacing arms, had the best adsorption capacities and good blood compatibility, It is hopeful to be used as adsorbent in hemoperfusion for clinical clearance of endotoxin. The influence of original concentration of endotoxin on adsorption and the adsorption mechanism were also investigated.

  17. Composites

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  18. Photochemistry of Nitrate Adsorbed on Mineral Dust

    Gankanda, A.; Grassian, V. H.

    2013-12-01

    Mineral dust particles in the atmosphere are often associated with adsorbed nitrate from heterogeneous reactions with nitrogen oxides including HNO3 and NO2. Although nitrate ion is a well-studied chromophore in natural waters, the photochemistry of adsorbed nitrate on mineral dust particles is yet to be fully explored. In this study, wavelength dependence of the photochemistry of adsorbed nitrate on different model components of mineral dust aerosol has been investigated using transmission FTIR spectroscopy. Al2O3, TiO2 and NaY zeolite were used as model systems to represent non-photoactive oxides, photoactive semiconductor oxides and porous materials respectively, present in mineral dust aerosol. In this study, adsorbed nitrate is irradiated with 254 nm, 310 nm and 350 nm narrow band light. In the irradiation with narrow band light, NO2 is the only detectable gas-phase product formed from nitrate adsorbed on Al2O3 and TiO2. The NO2 yield is highest at 310 nm for both Al2O3 and TiO2. Unlike Al2O3 and TiO2, in zeolite, adsorbed nitrate photolysis to nitrite is observed only at 310 nm during narrow band irradiation. Moreover gas phase products were not detected during nitrate photolysis in zeolite at all three wavelengths. The significance of these differences as related to nitrate photochemistry on different mineral dust components will be highlighted.

  19. EMISSION REDUCTION FROM A DIESEL ENGINE FUELED BY CERIUM OXIDE NANO-ADDITIVES USING SCR WITH DIFFERENT METAL OXIDES COATED CATALYTIC CONVERTER

    B. JOTHI THIRUMAL

    2015-11-01

    Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in nanoparticle form on the major physiochemical properties and the performance of diesel. The fuel is modified by dispersing the catalytic nanoparticle by ultrasonic agitation. The physiochemical properties of sole diesel fuel and modified fuel are tested with ASTM standard procedures. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Cerium oxide acts as an oxygen-donating catalyst and provides oxygen for the oxidation of CO during combustion. The active energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall which results in reduction in HC emission by 56.5%. Furthermore, a low-cost metal oxide coated SCR (selective catalyst reduction, using urea as a reducing agent, along with different types of CC (catalytic converter, has been implemented in the exhaust pipe to reduce NOx. It was observed that a reduction in NOx emission is 50–60%. The tests revealed that cerium oxide nanoparticles can be used as an additive in diesel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

  20. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications. PMID:27131811

  1. Novel Fiber-Based Adsorbent Technology; FINAL

    The overall of this Department of Energy (DOE) Phase II SBIR program was to develop a new class of highly robust fiber-based adsorbents for recovery of heavy metals from aqueous waste-streams. The fiber-based adsorbents,when commercialized,will be used for clean up metals in aqueous waste-streams emanating from DOE facilities,industry,mining,and groundwater-cleanup operations.The amount of toxic waste released by these streams is of great significance.The U.S.Environment Protection Agency (EPA) reports that in 1990 alone,4.8 billion pounds of toxic chemicals were released into the environment.Of this waste,the metals-containing waste was the second largest contributor,representing 569 million pounds. This report presents the results of the Phase II program,which successfully synthesized noval fiber-based adsorbents for the removal of Group 12 metals(i.e.mercury),Group 14 metals (lead),and Group 10 metals(platinum and palladium) from contaminated groundwater and industrial waste streams.These fiber-based adsorbents are ideally suited for the recovery of metal ions from aqueous waste streams presently not treatable due to the degrading nature of corrosive chemicals or radioactive components in the feed stream. The adsorbents developed in this program rely on chemically resistant and robust carbon fibers and fabrics as supports for metal-ion selective ligands.These adsorbents demonstrate loading capacities and selectivities for metal ions exceeding those of conventional ion-exchange resins.The adsorbents were also used to construct filter modules that demonstrate minimal fouling,minimal compaction,chemical and physical robustness,and regeneration of metal loading capacity without loss of performance

  2. POTENTIAL USE OF WOOL WASTE AS ADSORBENT FOR THE REMOVAL OF ACID DYES FROM WASTEWATER

    BUCIŞCANU Ingrid

    2016-05-01

    Full Text Available At present, great amounts of raw wool are treated as waste and raise disposal problems. In the sustainable development context , wool is regarded as a biodegradable renewable resource and due to its complex chemical composition and fiber morphology, can find different useful applications. It is the aim of this paper to investigate the potential use of raw wool waste as a non-conventional adsorbent for Acid Red 337(AcR ,currently used for leather and wool dyeing. Two wool-based adsorbents were prepared, namely scoured coarse wool (Wool-S and wool activated with alcoholic solution of sodium hydroxide (Wool-A. Adsorbent dosage, dye concentration, pH and treatment time were factors taken in consideration for the assessment of the sorbate-adsorbent interaction. The removal efficiency (R % is mainly dependent on the solution pH and on the activation treatment applied to wool: at pH 3, the removal efficiency reaches the highest values of 42% on Wool-S and 99% on Wool-A. The adsorption rate is slow and needs almost 6 h to reach equilibrium. The experimental data best fitted the Langmuir equilibrium adsorption model, which proves that the adsorbent possess surface active sites to which the dye sorbate binds in monomolecular layer. Raw wool waste is a potential cheap, biodegradable and effective adsorbent for colored wastewater treatment.

  3. Superparamagnetic iron oxide coated on the surface of cellulose nanospheres for the rapid removal of textile dye under mild condition

    Qin, Yunfeng; Qin, Zongyi; Liu, Yannan; Cheng, Miao; Qian, Pengfei; Wang, Qian; Zhu, Meifang

    2015-12-01

    Magnetic composite nanoparticles (MNPs) were prepared by anchoring iron oxide (Fe3O4) on the surface of carboxyl cellulose nanospheres through a facile chemical co-precipitation method. The as-prepared MNPs were characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction measurement, thermal gravity analysis and vibrating sample magnetometry. These MNPs were of a generally spherical shape with a narrow size distribution, and exhibited superparamagnetic behaviors with high saturation magnetization. High efficient removal of Navy blue in aqueous solution was demonstrated at room temperature in a Fenton-like system containing the MNPs and H2O2, which benefited from small particle size, large surface area, high chemical activity, and good dispersibility of the MNPs. The removal efficiency of Navy blue induced by the MNPs prepared at a weight ratio of cellulose to iron of 1:2 were 90.6% at the first minute of the degradation reaction, and 98.0% for 5 min. Furthermore, these MNPs could be efficiently recycled and reused by using an external magnetic field. The approach presented in this paper promotes the use of renewable natural resources as templates for the preparation and stabilization of various inorganic nanomaterials for the purpose of catalysis, magnetic resonance imaging, biomedical and other potential applications.

  4. Growth, microstructure and mechanical properties of microarc oxidation coatings on titanium alloy in phosphate-containing solution

    Wang Yaming; Lei Tingquan; Jiang Bailing; Guo Lixin

    2004-06-30

    Ceramic coatings were fabricated by microarc oxidation in galvanostatic regime on Ti6Al4V alloy in (NaPO{sub 3}){sub 6}-NaF-NaAlO{sub 2} solution. The growth, microstructure and phase composition of coatings were investigated using scanning electron microscope and X-ray diffraction. With increasing treatment duration, coating growth varies from rapidness to tardiness accompanied by gradually roughening in appearance. Meanwhile, phase transformation of anatase to rutile occurs. The crystalline AlPO{sub 4} is involved in the coatings via high-temperature thermolysis of hydrated aluminium polyphosphates in the nearby discharging channels. The stepped current regime enables coating structure to be controllable. The mechanical properties distribution across the coating thickness and the adhesion strength were determined by nanoindentation and shear test, respectively. A similar evolution profile of hardness and elastic modulus across the coating thickness is found: remaining high values (5.5 and 69.1 GPa) in the compact region before finally declining to low values (5.1 and 65.6 GPa) in the looser region. The adhesion strength of substrate/coating interface is about 40 MPa.

  5. Corrosion and bioactivity performance of graphene oxide coating on TiNb shape memory alloys in simulated body fluid.

    Saud, Safaa N; Hosseinian S, Raheleh; Bakhsheshi-Rad, H R; Yaghoubidoust, F; Iqbal, N; Hamzah, E; Ooi, C H Raymond

    2016-11-01

    In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of TiNb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35μm to 45μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated TiNb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37°C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications. PMID:27524069

  6. Electro-Mechanical Coupling of Indium Tin Oxide Coated Polyethylene Terephthalate ITO/PET for Flexible Solar Cells

    Saleh, Mohamed A.

    2013-05-15

    Indium tin oxide (ITO) is the most widely used transparent electrode in flexible solar cells because of its high transparency and conductivity. But still, cracking of ITO on PET substrates due to tensile loading is not fully understood and it affects the functionality of the solar cell tremendously as ITO loses its conductivity. Here, we investigate the cracking evolution in ITO/PET exposed to two categories of tests. Monotonous tensile testing is done in order to trace the crack propagation in ITO coating as well as determining a loading range to focus on during our study. Five cycles test is also conducted to check the crack closure effect on the resistance variation of ITO. Analytical model for the damage in ITO layer is implemented using the homogenization concept as in laminated composites for transverse cracking. The homogenization technique is done twice on COMSOL to determine the mechanical and electrical degradation of ITO due to applied loading. Finally, this damage evolution is used for a simulation to predict the degradation of ITO as function in the applied load and correlate this degradation with the resistance variation. Experimental results showed that during unloading, crack closure results in recovery of conductivity and decrease in the overall resistance of the cracked ITO. Also, statistics about the crack spacing showed that the cracking pattern is not perfectly periodical however it has a positively skewed distribution. The higher the applied load, the less the discrepancy in the crack spacing data. It was found that the cracking mechanism of ITO starts with transverse cracking with local delamination at the crack tip unlike the mechanism proposed in the literature of having only cracking pattern without any local delamination. This is the actual mechanism that leads to the high increase in ITO resistance. The analytical code simulates the damage evolution in the ITO layer as function in the applied strain. This will be extended further to

  7. Black Molecular Adsorber Coatings for Spaceflight Applications

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  8. Defluoridization Using a Natural Adsorbent, Strychnos Potatorum

    S.Rayappan

    2014-10-01

    Full Text Available The study assessed the suitability of low-cost natural adsorbent to effectively remediate fluoride contaminated water. The removal of fluoride from aqueous solution by using Strychnos Potatorum was studied in batch technique. Influence of pH, adsorbent dose, contact time, co ions, speed and initial concentration on the adsorption were investigated. The maximum removal of fluoride ion was obtained at pH 7. The removal of fluoride was expressed with Langmuir and Freundlich isotherm. It was found that the sufficient time for adsorption equilibrium of fluoride ion was 1 hour. The removal of fluoride ions was maximum for the adsorbent dosage of SP is 50mg/50ml. The fluoride adsorption was maximum at 60minutes. The adsorption of F- ion was maximum in the shaking speed of 120 rpm. The presence of interfering ions such as nitrate and carbonate showed positive effect while sulphate and chloride showed little negative effect and phosphate showed high negative effect for the adsorbent. The optimum initial fluoride concentration for SP adsorbent was 1mg/50ml.

  9. Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

    Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time

  10. Novel adsorbent from agricultural waste (cashew NUT shell) for methylene blue dye removal: Optimization by response surface methodology

    Ramalingam Subramaniam; Senthil Kumar Ponnusamy

    2015-01-01

    Activated carbon, prepared from an agricultural waste, cashew nut shell (CNS) was utilized as an adsorbent for the removal of methylene blue (MB) dye from aqueous solution. Batch adsorption study was carried out with variables like pH, adsorbent dose, initial dye concentration and time. The response surface methodology (RSM) was applied to design the experiments, model the process and optimize the variable. A 24 full factorial central composite design was successfully employed for experimenta...

  11. Signal enhancement in electrospray laser desorption/ionization mass spectrometry by using a black oxide-coated metal target and a relatively low laser fluence.

    Kononikhin, Alexey; Huang, Min-Zong; Popov, Igor; Kostyukevich, Yury; Kukaev, Evgeny; Boldyrev, Alexey; Spasskiy, Alexander; Leypunskiy, Ilya; Shiea, Jentaie; Nikolaev, Eugene

    2013-01-01

    The electrospray Laser desorption/ionization (ELDI) method is actively used for direct sample analysis and ambient mass spectrometry imaging. The optimizing of Laser desorption conditions is essential for this technology. In this work, we propose using a metal target with a black oxide (Fe3O4) coating to increase the signal in ELDI-MS for peptides and small proteins. The experiments were performed on an LTQ-FT mass spectrometer equipped with a home-made ELDI ion source. A cutter blade with black oxide coating was used as a target. A nitrogen laser was used with the following parameters: 337 nm, pulse duration 4ns, repetition rate 10 Hz, fluence to approximately 700 Jm(-2). More than a five times signal increase was observed for a substance P peptide when a coated and a non-coated metal target were compared. No ion signal was observed for proteins if the same fluence and the standard stainless steel target were used. With the assistance of the Fe3O4 coated metal target and a relatively low laser fluence < or =700 Jm(-2)), proteins such as insulin, ubiquitin and myoglobin were successfully ionized. It was demonstrated that the Fe3O4-coated metal target can be used efficiently to assist laser desorption and thus significantly increase the analyte signal in ELDI-MS. A relatively low laser fluence (< or = 700 Jm(-2)) was enough to desorb peptides and proteins (up to 17 kDal with the assistance of the Fe3O4-coated metal target under ambient conditions. PMID:24575623

  12. Electrochemical behavior of LiFePO4 cathode materials in the presence of anion adsorbents

    The poor rate capability is a major problem of olivine-structured lithium iron phosphate (LFP) cathode material in lithium-ion batteries due to its low electric conductivity and sluggish lithium diffusion. Other than the custom strategies to solve this problem like carbon coating and nano-size treatment, we simply mixed LFP with some anion adsorbents, which can store anions from the electrolytes swiftly. The effect of anion adsorbents on the performance of LFP composite electrode has been investigated by cyclic voltammetric tests and the corresponding apparent lithium diffusion coefficients have been measured

  13. Theoretical Insight of Physical Adsorption for a Single Component Adsorbent + Adsorbate System: II. The Henry Region

    Chakraborty, Anutosh

    2009-07-07

    The Henry coefficients of a single component adsorbent + adsorbate system are calculated from experimentally measured adsorption isotherm data, from which the heat of adsorption at zero coverage is evaluated. The first part of the papers relates to the development of thermodynamic property surfaces for a single-component adsorbent + adsorbate system1 (Chakraborty, A.; Saha, B. B.; Ng, K. C.; Koyama, S.; Srinivasan, K. Langmuir 2009, 25, 2204). A thermodynamic framework is presented to capture the relationship between the specific surface area (Ai) and the energy factor, and the surface structural and the surface energy heterogeneity distribution factors are analyzed. Using the outlined approach, the maximum possible amount of adsorbate uptake has been evaluated and compared with experimental data. It is found that the adsorbents with higher specific surface areas tend to possess lower heat of adsorption (ΔH°) at the Henry regime. In this paper, we have established the definitive relation between Ai and ΔH° for (i) carbonaceous materials, metal organic frameworks (MOFs), carbon nanotubes, zeolites + hydrogen, and (ii) activated carbons + methane systems. The proposed theoretical framework of At and AH0 provides valuable guides for researchers in developing advanced porous adsorbents for methane and hydrogen uptake. © 2009 American Chemical Society.

  14. Preparation and tribological properties of self-lubricating TiO2/graphite composite coating on Ti6Al4V alloy

    Highlights: ► A TiO2/graphite composite coating is produced on Ti alloy by one-step PEO process. ► The TiO2/graphite composite coating exhibits excellent self-lubricating behavior. ► The self-lubricating composite coating improves the wear resistance by comparison to the conventional PEO coating. - Abstract: One-step plasma electrolytic oxidation (PEO) process in a graphite-dispersed phosphate electrolyte was used to prepare a graphite-containing oxide composite coating on Ti6Al4V alloy. The composition and microstructure of the oxide coatings produced in the phosphate electrolytes with and without addition of graphite were analyzed by X-ray diffractometer (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The tribological properties of the uncoated Ti6Al4V alloy and oxide coatings were evaluated using a reciprocating ball-on-disk tribometer. Results showed that the graphite-containing oxide composite coating can be successfully produced on Ti6Al4V alloy in the graphite-dispersed phosphate electrolyte using PEO process. The graphite-containing oxide composite coating registered much lower friction coefficient and wear rate than the uncoated Ti6Al4V alloy and the oxide coating without graphite under dry sliding condition, exhibiting excellent self-lubricating property.

  15. Effect of Adsorbent Diameter on the Performance of Adsorption Refrigeration

    黄宏宇; 何兆红; 袁浩然; 小林敬幸; 赵丹丹; 窪田光宏; 郭华芳

    2014-01-01

    Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.

  16. The Dynamics and Structures of Adsorbed Surfaces

    Nielsen, M; Ellenson, W. D.; McTague, J. P.

    1978-01-01

    Reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace. ...

  17. Antiferromagnets Structure in Adsorbed O2 Monolayers

    Nielsen, Mourits; McTague, J. P.

    1977-01-01

    Neutron diffraction from monolayers of O2 adsorbed on graphite shows structural arrangements similar to the dense planes of bulk O2. At monolayer completion and above, a magnetic superlattice reflection shows well-developed antiferromagnetic order for T ⩽ 10 K. The submonolayer phase also shows...

  18. Organosilicon Ion-Exchange and Complexing Adsorbents

    M. Voronkov; N. Vlasova; Yu. Pozhidaev; L. Belousova

    2005-01-01

    @@ 1Introduction Modification of mineral synthetic or natural substrates by organosilicon G-functionally substituted monomers, copolycondensation of the latter with organic and organosilicon compounds, and hydrolytic polycondensation of these monomers are the most widely used methods of synthesis of organosilicon adsorbents.

  19. Study of plutonium adsorption by fibrous adsorbent

    Japan Atomic Energy Research Institute and Unitika Ltd. have been conducting, under a joint effort, development of an inorganic fibrous adsorbent (FAC), which is capable of adsorbing plutonium (Pu) contained in radioactive liquid waste and which is also able to contribute to reduction of the volume of α-waste by incineration. The fibrous adsorbent constitutes fibrous activated carbon of coal tar pitch derivative and has the following characteristics: (1) It has a large surface area. (2) Carbon constitutes more than 90% in the adsorbent; it is physically and chemically stable as an inorganic adsorbent; it is easy to be incinerated. (3) It is easy to be formed or molded into different shapes such as cartridges, and handling of the material is extremely easy. By using various kinds of Pu solution, we carried out tests and evaluations on the equilibrium adsorption quantity of Pu by the fibrous adsorbent, the adsorption property of the material by flow-through column test and the incineration property of the material in the cold test. The tests show that: (1) adsorption of Pu is the best with 0.8∼0.9 mg-Pu/g-FAC when the concentration of nitric acid is near 1 M; (2) as the concentration of nitric acid is increased, its adsorption capacity becomes poorer; (3) when Pu coexists with Uranium (U), the adsorption capacity becomes slightly inferior; (4) in the flow-through column test, no breakthrough of Pu was observed until the volume of Pu liquid becomes about 3 times larger than the column volume; (5) in the incineration tests in the cold test using a laboratory scale incinerator, no flying of particles or soot was observed; and (6) it is possible to get good incineration at 500 ∼ 600 degrees C. The above results show that, by using the fibrous adsorbent, it became possible to remove Pu from radioactive liquid waste by adsorption, to reduce the volume only to residual ash by incineration, and to reduce substantially the volume of α-waste

  20. Adsorbent cartridge for the exhaust of diazo process machines

    A disposable cartridge filled with a chemical composition that acts as an adsorbent for ammonia vapor is adapted to be used in connection with a diazo process printing machine having a vacuum exhausted chamber. Exhaust from the chamber is passed through the cartridge to remove the noxious ammonia vapors and then is vented into the atmosphere. The cartridge is housed in an elongated rectangular cardboard box having three end flaps formed at each of its opposed open ends. Two opposed flaps of each set are formed with central holes and a plastic screen section adhered between these flaps to retain and allow access to the center section of the box which contains the adsorbent chemical. The center end flaps have knock-outs or tear strips that allow holes to be formed in their centers. These center end flaps cover the screens during shipment and when the cartridge is ready for use the center sections of these end flaps are knocked-out to allow the machine exhaust to be vented into and out of the cartridge

  1. Geometric rearrangement of adsorbate driven by the charge transfer

    Pavlyukh, Yaroslav; Berakdar, Jamal [Institut fuer Physik, Martin-Luther-Universitaet Halle-Wittenberg, Halle (Germany); Huebner, Wolfgang [Department of Physics and Research Center OPTIMAS, Kaiserslautern University of Technology (Germany)

    2010-05-15

    Adsorption of alkali atoms induces a significant charge redistribution in the region around the adatom. Such charge displacement is associated with a large dipole moment responsible for the interaction of adatoms and a reduction of the surface work function. In addition to these well-known effects our first principles simulations for the Na{sub 9}{sup +} cluster on the Cu(001) surface demonstrate how the charge transfer (CT) from the adsorbate to the substrate can drastically change the geometric structure of the cluster. We report on a detailed study of the adsorption process using quantum chemistry. A representation of the substrate by a cluster of 54 Cu atoms allows us to treat quantum mechanically the electronic structure of both systems, the adsorbate and the surface, on equal footing. Subsequently, we analyze the charge distribution in the composite system. Convergence of the results is verified by considering a much larger substrate cluster containing 126 Cu atoms. The role of the CT is further elucidated by the geometry optimization of the bare cluster with and without an electron deficit. It is shown that the CT drives the system to a meta-stable state which thereafter relaxes to a new configuration. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    Visa, Maria, E-mail: maria.visa@unitbv.ro [Transilvania University of Brasov, Department Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The spent adsorbent annealed at 500 Degree-Sign C can be a suggestion for padding in stone blocks. Black-Right-Pointing-Pointer The cations can be adsorbent by the silanol group (Si-OH) of the layers from bentonite Black-Right-Pointing-Pointer Copper has a higher affinity for the active sites on adsorbent FAw + B than cadmium. Black-Right-Pointing-Pointer This substrate can be recommended for simultaneous removal of heavy metals and MB. Black-Right-Pointing-Pointer FAw + B is recommended for wastewater treatment resulted in the dyes finishing industry. - Abstract: Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 Degree-Sign C can be reused for padding in stone blocks.

  3. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    Highlights: ► The spent adsorbent annealed at 500 °C can be a suggestion for padding in stone blocks. ► The cations can be adsorbent by the silanol group (Si-OH) of the layers from bentonite ► Copper has a higher affinity for the active sites on adsorbent FAw + B than cadmium. ► This substrate can be recommended for simultaneous removal of heavy metals and MB. ► FAw + B is recommended for wastewater treatment resulted in the dyes finishing industry. - Abstract: Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

  4. New catalysts and adsorbents on the basis of the InSb-CdTe semiconducting system

    The acid-base, adsorption, and catalytic properties of solid solutions and binary components of the InSb-CdTe system were studied. The nature, strength, and concentration of acid centers were determined. Changes in the concentration of acid centers under the action of gases (NO2 and NH3), gamma radiation, and composition variations were estimated. The experimental dependences, thermodynamic and kinetic adsorption characteristics, the electrophysical, acid-base, and other physicochemical characteristics of the adsorbents, and adsorption characteristic-composition phase diagrams were analyzed taking into account the electronic nature of adsorbate molecules to determine the mechanism and characteristics of adsorption processes depending on the conditions of adsorption and the composition of the system

  5. Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

    Highlights: ► Prussian blue was sealed in cavities of diatomite using carbon nanotubes. ► The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. ► Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water. - Abstract: We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

  6. Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

    Hu, Baiyang [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Yu, Hongwen [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Abe, Yoshiteru [Kyoei Engineering Corporation, Niigata 959-1961 (Japan)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer Prussian blue was sealed in cavities of diatomite using carbon nanotubes. Black-Right-Pointing-Pointer The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. Black-Right-Pointing-Pointer Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water. - Abstract: We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

  7. PVDF membranes containing hybrid nanoparticles for adsorbing cationic dyes: physical insights and mechanism

    Sharma, Maya; Madras, Giridhar; Bose, Suryasarathi

    2016-07-01

    In this study, Fe (iron) and Ag (silver) based adsorbents were synthesized using solution combustion and in situ reduction techniques. The synthesized adsorbents were comprehensively characterized by different techniques including electron microscopy, BET, XRD, Zeta potential etc. Three chlorinated cationic dyes used were malachite green, methyl violet and pyronin Y. These dyes were adsorbed on various synthesized adsorbents [iron III oxide (Fe2O3)], iron III oxide decorated silver nanoparticles by combustion synthesis technique [Fe2O3–Ag(C)] and iron III oxide decorated silver nanoparticles using in situ reduction, [Fe2O3–Ag (S)]. The isotherm and the adsorption kinetics have been studied systematically. The kinetic data can be explained by the pseudo second order model and the adsorption equilibrium followed Langmuir isotherm. The equilibrium and kinetics results suggest that Fe2O3–Ag(S) nanoparticles showed the maximum adsorption among all the adsorbents. Hence, Polyvinylidene fluoride based membranes containing Fe2O3–Ag(S) nanoparticles were prepared via phase inversion (precipitation immersion using DMF/water) technique. The adsorption kinetics were studied in detail and it was observed that the composite membrane showed synergistic improvement in dye adsorption. Such membranes can be used for water purification.

  8. Lutetium Oxide Coatings by PVD

    Topping, Stephen G; Park, CH; Rangan, SK; Sarin, VK

    2007-01-01

    Due to its high density and cubic structure, Lutetium oxide (Lu2O3) has been extensively researched for scintillating applications. Present manufacturing methods, such as hot pressing and sintering, do not provide adequate resolution due to light scattering of polycrystalline materials. Vapor deposition has been investigated as an alternative manufacturing method. Lutetium oxide transparent optical coatings by magnetron sputtering offer a means of tailoring the coating for optimum scintillati...

  9. Preparation, characterization and application of a Ce-Ti oxide adsorbent for enhanced removal of arsenate from water

    Different metal doped TiO2 adsorbents were prepared through the precipitation and hydrolysis-precipitation methods. The novel Ce-Ti oxide adsorbent obtained by the hydrolysis-precipitation had much higher sorption capacity for As(V) than both the pure titanium dioxide and cerium oxide adsorbents, and the preparation conditions including the Ti/Ce molar ratio and polyvinyl alcohol (PVA) content were optimized. Environmental scanning electronic microscopy (ESEM) and X-ray diffraction (XRD) spectroscopic investigations revealed that the amorphous Ce-Ti hybrid adsorbent was composed of some nanoparticles in the size range of 100-200 nm, which aggregated to form the porous hybrid adsorbents, and the amorphous compositions and the small nanoparticles were related to the high sorption capacity for As(V). Batch sorption experiments including sorption kinetics, isotherm, effect of pH and competitive ions were investigated. The Ce-Ti adsorbent exhibited high sorption capacity for As(V) at pH below 7. Column studies showed that about 72,085 bed volumes of As(V) solution at the concentration of 50 μg L-1 and pH 6.5 were filtered when As(V) concentration in the effluent increased to 10 μg L-1, and the average sorption capacity of As(V) on the Ce-Ti adsorbent was about 9.4 mg g-1.

  10. ZM5镁合金微弧氧化膜的摩擦磨损性能研究%Study on Friction and Wear Property of Micro-arc OxidationCoating on ZM5 Magnesium Alloy

    胡慧玲; 吴向清; 谢发勤; 杜肖

    2011-01-01

    利用微弧氧化装置在硅酸盐体系中对ZM5镁合金进行了微弧氧化表面改性处理.采用XRD及SEM分析了ZM5镁合金微弧氧化陶瓷膜的形貌、组成和结构,并对微弧氧化陶瓷膜的硬度以及干式滑动摩擦磨损行为进行了研究.结果表明:微弧氧化膜由三层结构组成,主要由Mg2SiO4相和少量MgO相组成;可以显著提高镁合金基体的硬度和耐磨性,其室温滑动摩擦磨损机理为轻微犁削和粘附转移.%Micro-arc oxidation coating was deposited on ZM5 alloy sample using MAO processing in silicate system. The morphology, content and structure of micro-arc oxidation ceramic coating were investigated by XRD and SEM. The microhardness, friction and wear behavior under dry sliding were also measured. The results show that the micro-arc oxidation coating can be divided into three stratums and the constituent phases mainly are Mg2SiO4 and MgO, The micro-arc oxidation coating can evidently improve the anti-wear performance and rigidity of magnesium. The wear mechanism of the coating is light furrow and conglutinating diversion.

  11. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Yuan Lu

    2016-05-01

    Full Text Available Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ∼16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  12. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Lu, Yuan; Zhou, Tie-ge; Shao, Bin; Zuo, Xu; Feng, Min

    2016-05-01

    Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ˜16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  13. Development of XZ-1200 ripple-bed iodine adsorber

    The structure and specifications of XZ-1200 ripple-bed iodine adsorbers are described in detail. The performance of the adsorbers in use in Daya Bay NPP are presented and compared with that of the French ones

  14. Di(isothiocyanato)bis(4-methyl-4’-vinyl-2,2’-bipyridine) Ruthenium(II) Films Deposited on Titanium Oxide-Coated, Fluorine-Doped Tin Oxide for an Efficient Solar Cell

    Liu, Yi; Sugimoto, Ryuichi; Sumi, Katsuhiro

    2013-01-01

    Dye-sensitized titanium oxide electrodes were prepared by immobilizing a novel ruthenium complex, di(isothiocy- anato)bis(4-methyl-4’-vinyl-2,2’-bipyridine)ruthenium(II) [(NCS)_2(mvbpy)_2Ru(II)] or the ruthenium complex/sodium 4-vinylbenzenesulfonate onto the surface of a titanium oxide-coated, fluorine-doped tin oxide (TiO_2/FTO) electrode through a new electrochemically initiated film formation method, in which the electrolysis step and the film deposition step were individually performed. ...

  15. Roughness and contact angles of micro-arc oxidation coating on the surface of titanium%纯钛表面微弧氧化膜的粗糙度与接触角

    王磊; 陈建治; 唐建国; 贾暮云; 石玉龙; 闫风英

    2009-01-01

    目的:分析纯钛表面微弧氧化改性对表面氧化膜特性的影响.方法:通过微弧氧化技术在含一定钙磷比例的电解液中制备纯钛表面氧化膜层,进而检测纯钛表面微弧氧化膜的粗糙度和接触角.结果:微弧氧化处理后,纯钛表面生成微孔结构的氧化膜,直径1~5 μm.氧化膜层中含Ti、O、Ca、P4种元素,由锐钛矿型、金红石型二氧化钛,结晶相羟基磷灰石组成;微弧氧化试样的表面粗糙度明显高于未处理纯钛试样(P<0.05),表面接触角小于未处理纯钛试样(P<0.05).结论:经微弧氧化技术处理后,纯钛表面生成了多孔的二氧化钛膜,含羟基磷灰石.膜层表面粗糙度增大,接触角减小,有利于细胞的附着和骨组织的整合.%OBJECTIVE: To analyze the influence of surface modification of pure titanium by micro-arc oxidation on surface oxidation coating features. METHODS: The oxidation coating was prepared on titanium surface by using micro-arc oxidation in electrolyte containing calcium and phosphonium at certain ratio, and the roughness and contact angles of the new oxidation coating were detected. RESULTS: Ceramic microporous coating was formed on titanium surface with micro-arc oxidation, 1-5 urn in diameter. On the surface, the coating was made from O, Ti, Ca, and P elements. The phase components of the coating included anatase, rutile and hydroxyapatite. The surface roughness of micro-arc oxidation specimens was significantly increased (P < 0.05), and contact angles were significantly decreased following micro-arc oxidation (P < 0.05). CONCLUSION: The oxidation coating with micropores, hydroxy-apatite, increased roughness and decreased contact angles on titanium surface formed following micro-arc oxidation, which benefits cell adherence and bone tissue integration.

  16. Zeolites as alcohol adsorbents from aqueous solutions

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  17. Computer simulations of adsorbed liquid crystal films

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  18. Study on the gamma-ray irradiation behavior of mesoporous silica adsorbents functionalized with phosphine oxide and phosphonic acid ligands

    The resistance of mesoporous silica adsorbents bearing phosphine oxide (SBA-P(O)Pr2) and phosphonic acid (SBA-P(O)(OH)2) to gamma-ray irradiation (in air and 2 mol/ L HNO3 solution) was systematically evaluated. The change in the composition, structure and (U(VI)) adsorption ability of the adsorbents was examined. Both the organophosphorus ligands functionalized adsorbents exhibited remarkable durability under gamma-ray irradiation up to a total dose of 5 x 105 Gy. The mesoporous silica framework and the two classes of organophosphorus ligands were well-reserved without irradiation damage. Moreover, after irradiation, the adsorbents still maintained an effective adsorption of U(VI) in high acidic or pH range solutions. (author)

  19. Removal of hydrogen sulfide from biogas on sludge-derived adsorbents

    Weixin Yuan; Teresa J. Bandosz [City College of The City University of New York, New York, NY (United States). Department of Chemistry

    2007-12-15

    Desulfurization adsorbents were prepared from the mixtures of sewage sludge and metal sludge of various compositions and individual sludges by pyrolyses at 650, 800 and 950{sup o}C. The resulting materials were used as adsorbents of hydrogen sulfide from simulated digester gas mixture. The adsorbents before and after H{sub 2}S removal were characterized using adsorption of nitrogen, elemental analysis, pH measurements, and thermal analysis. The behavior of materials as desulfurization media does not depend strongly on the humidification pretreatment. The pyrolysis temperature and composition of the mixture play a role in the development of final properties of adsorbents. When the content of sewage sludge is high the strong synergetic effect is noticed after high temperature of pyrolysis. Such factors as development of mesoporosity and new catalytic phases formed as a result of solid-state reactions contribute to this behavior. The removal of hydrogen sulfide on the materials obtained is complex due to the competition between H{sub 2}S and CO{sub 2} for adsorption centers and deactivation of those centers by CO{sub 2}/H{sub 2}CO{sub 3}. 38 refs., 12 figs., 6 tabs.

  20. Removal of micropollutants from water by nanocomposite membrane adsorbers

    Niedergall, K.; Bach, M.; Hirth, T.; Tovar, G.E.M.; Schiestel, T.

    2014-01-01

    Nanoscaled spheric polymer adsorbers with a variety of chemical surface functionalities were synthesized by miniemulsion polymerization and inverse miniemulsion polymerization. The nanospheres were embedded in polyethersulfone (PES) matrices by a wet-phase inversion process to form nanocomposite membrane adsorbers. The resulting membrane adsorbers were characterized by scanning electron microscopy (SEM), pore size measurements, water flux measurements and various adsorption experiments. The m...

  1. Characterising electrospun nanofibre adsorbents for bioprocessing

    Dods, S. R.

    2016-01-01

    Biopharmaceutical manufacturing is one of largest sectors in the world and purification steps are expensive. Packed-bed resins are widely used, but are limited by diffusion mass transfer. Convective mass transfer media offer improved productivities using high flowrates. Electrospun nanofibres are a non-woven with an open structure and high surface area. Cellulose acetate was electrospun into reproducible adsorbents and activation methodologies were evaluated. Aldehyde activation caused degrad...

  2. Behavior of macromolecules in adsorbed layers

    牟伯中[1; 姚恒申[2; 罗平亚[3

    2000-01-01

    A model for describing the behavior ot macromoiecuies in aosoroea layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics. The molecular behavior of layers adsorbed on clay particle surfaces is discussed; the random distribution and its statistics of the layer thickness are given by incorporating experimental results with an ionic polyelectrolyte with the molecular weight of 1.08×106and chain charged density of 0.254.

  3. Indirect interactions of membrane-adsorbed cylinders

    Weikl, Thomas R.

    2003-01-01

    Biological and biomimetic membranes often contain aggregates of embedded or adsorbed macromolecules. In this article, the indirect interactions of cylindrical objects adhering to a planar membrane are considered theoretically. The adhesion of the cylinders causes a local perturbation of the equilibrium membrane shape, which leads to membrane-mediated interactions. For a planar membrane under lateral tension, the interaction is repulsive for a pair of cylinders adhering to the same side of the...

  4. Orbital tomography for highly symmetric adsorbate systems

    Stadtmüller, B.; Willenbockel, M.; Reinisch, E. M.; Ules, T.; Bocquet, F. C.; Soubatch, S.; Puschnig, P.; Koller, G.; Ramsey, M. G.; Tautz, F. S.; Kumpf, C.

    2012-10-01

    Orbital tomography is a new and very powerful tool to analyze the angular distribution of a photoemission spectroscopy experiment. It was successfully used for organic adsorbate systems to identify (and consequently deconvolute) the contributions of specific molecular orbitals to the photoemission data. The technique was so far limited to surfaces with low symmetry like fcc(110) oriented surfaces, owing to the small number of rotational domains that occur on such surfaces. In this letter we overcome this limitation and present an orbital tomography study of a 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) monolayer film adsorbed on Ag(111). Although this system exhibits twelve differently oriented molecules, the angular resolved photoemission data still allow a meaningful analysis of the different local density of states and reveal different electronic structures for symmetrically inequivalent molecules. We also discuss the precision of the orbital tomography technique in terms of counting statistics and linear regression fitting algorithm. Our results demonstrate that orbital tomography is not limited to low-symmetry surfaces, a finding which makes a broad field of complex adsorbate systems accessible to this powerful technique.

  5. Removal of adsorbent particles od copper ions by Jet flotation

    The present study shows the results obtained on the removal of copper ions from synthetic effluents by using the adsorbent particles flotation technique (APF) in a Jet flotation cell (Jameson type). In a typical experimental run, a mineral with high quartz content was used as adsorbent particles in the adsorption and flotation experiments, to determine optimal pH conditions, adsorbent particles concentration; flotation reagents dosage and air/effluent flow ratio for applying in the Jet cell to maximize the efficiency of copper ions adsorptions and the removal of particles adsorbents containing the absorbed copper ions. The results indicate the at pH>7 and at adsorbent particles concentration of 2 kg.m-3, 99% of copper ions is adsorbed and, when the air/effluent flow ratio applied in the Jet cell is 0,2, 98% of absorbent particles containing the adsorbed copper ions is removed. (Author) 39 refs.

  6. Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

    Hu, Baiyang; Fugetsu, Bunshi; Yu, Hongwen; Abe, Yoshiteru

    2012-01-01

    We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/P...

  7. Adsorption equilibria and kinetics for phenol and cresol onto polymeric adsorbents: Effects of adsorbents/adsorbates structure and interface

    Phenol and cresol (o-, m-, and p-) were selected as the adsorbates with different dipole moment (cresol > phenol, methyl being electron-drawing group) and solubility (phenol > cresol, methyl being hydrophobic group). Macropore polymers (NDA-1800 and XAD-4), hypercrosslinked polymers (NDA-100), and chemically modified adsorbents (NDA-150 and NDA-99), were comparatively used to investigate the adsorption properties including equilibria, thermodynamics and kinetics. First, all of the results about equilibria show that the adsorption data fit well to the Freundlich model. The adsorption capacity of NDA-99 and NDA-150 especially for phenol is larger in a certain extent than other three types of polymers. The hydrophobic interaction from large specific surface was mainly occurred, while the polar groups containing oxygen and amine markedly enhance the adsorption process via hydrogen interaction. Furthermore, the adsorption amount for NDA-99 and XAD-4 decrease linearly with the solubility of solutes tested. Then, the negative values of enthalpy demonstrate the predominantly exothermic and physical solid-extraction processes. Finally, the relatively more rapid adsorption process could be found onto NDA-150 than NDA-99, with the reason of the double larger pore size of the former. In conclusion, solubility of solute, together with surface area, pore size and modified groups, extremely exerts influences to the adsorption performances

  8. The persistence length of adsorbed dendronized polymers.

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-21

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role. PMID:27353115

  9. Dye sequestration using agricultural wastes as adsorbents

    Kayode Adesina Adegoke

    2015-12-01

    Full Text Available Color is a visible pollutant and the presence of even minute amounts of coloring substance makes it undesirable due to its appearance. The removal of color from dye-bearing effluents is a major problem due to the difficulty in treating such wastewaters by conventional treatment methods. The most commonly used methods for color removal are biological oxidation and chemical precipitation. However, these processes are effective and economic only in the case where the solute concentrations are relatively high. Most industries use dyes and pigments to color their products. The presence of dyes in effluents is a major concern due to its adverse effect on various forms of life. The discharge of dyes in the environment is a matter of concern for both toxicological and esthetical reasons. It is evident from a literature survey of about 283 recently published papers that low-cost adsorbents have demonstrated outstanding removal capabilities for dye removal and the optimal equilibrium time of various dyes with different charcoal adsorbents from agricultural residues is between 4 and 5 h. Maximum adsorptions of acidic dyes were obtained from the solutions with pH 8–10. The challenges and future prospects are discussed to provide a better framework for a safer and cleaner environment.

  10. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  11. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of 4He adsorbed on metallic films. In contrast to measurements of 4He adsorbed on all other insulating substrates, we have shown that 4He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, 4He adsorbed on sapphire and on Ag films and H2 adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs

  12. From MDF and PB wastes to adsorbents for the removal of pollutants

    Gomes, J. A. F. L.; Azaruja, B. A.; Mourão, P. A. M.

    2016-09-01

    The production of activated carbons in powder and monolith forms, by physical activation with CO2, with specific surface areas between 804 and 1469 m2 g-1, porous volume between 0.33 and 0.59 cm3 g-1, with basic nature (PZC ∼ 9.6-10.6) was achieved in our lab, from medium density fibreboard (MDF) and particleboard (PB), engineered wood composites wastes. These highly porous adsorbents were applied in kinetic and equilibrium adsorption studies, in batch and dynamic modes, in powder and monolith forms, of specific adsorptives, considered pollutants, namely phenol (P), p-nitrophenol (PNP) and neutral red (NR). In batch the maximum adsorbed amount was 267, 162 and 92 mg g-1, for PNP, P and NR, respectively. The application of different kinetic models (pseudo-first order, pseudo-second order and intraparticle diffusion model) leads to a better knowledge of the adsorption mechanisms of those adsorptives. The results obtained in the kinetic and equilibrium tests show that the combination of the structural features and the surface chemistry nature of the adsorbents, with the adsorptives properties, establish the kinetic performance, the type and amount adsorbed for each system. This work confirms the potential of these types of wastes in the production of activated carbons and its application in adsorption from liquid phase.

  13. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  14. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    Visa, Maria

    2012-12-01

    Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

  15. A novel magnetic 4A zeolite adsorbent synthesised from kaolinite type pyrite cinder (KTPC)

    Wang, Weiqing; Feng, Qiming; Liu, Kun; Zhang, Guofan; Liu, Jing; Huang, Yang

    2015-01-01

    As a solid waste, kaolinite type pyrite cinder (KTPC) is a special pyrite cinder, its mineral components include metakaolin and magnetite, and the chemical compositions of these minerals include SiO2, Al2O3, FeO and Fe2O3. In this study, a novel magnetic 4A zeolite adsorbent was synthesised from KTPC using the hydrothermal method, and the optimum hydrothermal synthesis conditions were investigated using X-ray diffraction (XRD) and by determining the specific surface area (SSA) and the saturated cation exchange adsorption capacity (SCEAC) to Cs+. Under the optimum hydrothermal synthesis conditions, the magnetic 4A zeolite adsorbent can be synthesised with high crystallinity, and the SSA and SCEAC to Cs+ are 24.49 m2/g and 106.63 mg/g, respectively. The further characterisations of pore size distribution, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry-derivative thermogravimetry-differential thermal analysis (TG-DTG-DTA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) were performed. The results revealed that magnetic particles are coated onto the zeolite surface and further form magnetic aggregates, and the existing magnetic particles in KTPC do not change their crystal structure and do not affect the synthesis of the 4A zeolite. In addition, the synthesised 4A zeolite adsorbent can be used as a magnetic adsorbent in wastewater treatment with high magnetic sensitivity and is thermally stable up to approximately 900 °C.

  16. Investigation of drug-porous adsorbent interactions in drug mixtures with selected porous adsorbents.

    Madieh, Shadi; Simone, Michael; Wilson, Wendy; Mehra, Dev; Augsburger, Larry

    2007-04-01

    The adsorption of drugs onto porous substrates may prove to be a convenient method by which to enhance the dissolution rate of certain poorly water-soluble drugs in body fluids. The purpose of this research is to provide a better understanding of the type of interactions occurring between drugs and certain pharmaceutically acceptable porous adsorbents that leads to enhanced drug dissolution rates. The interactions between ibuprofen (acidic drug), acetaminophen (acidic drug), dipyridamole (basic drug), and the porous adsorbents used (calcium silicate and silica gel) were investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier Transform infrared spectroscopy (FTIR). DSC and PXRD results indicated a significant loss of crystallinity of both ibuprofen and acetaminophen but not dipyridamole. In the case of ibuprofen, FTIR results indicated the ionization of the carboxylic group based on the shift in the FTIR carboxylic band. Dissolution of ibuprofen from its mixtures with porous adsorbents was found to be significantly higher compared to the neat drug, whereas dipyridamole dissolution from its mixtures with porous adsorbents was not significantly different from that of the neat drug. PMID:17221849

  17. Equilibrium molecular theory of two-dimensional adsorbate drops on surfaces of heterogeneous adsorbents

    Tovbin, Yu. K.

    2016-08-01

    A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor-fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

  18. Evaluation of pharmaceuticals removal by sewage sludge-derived adsorbents with rapid small-scale column tests

    Zhang, P.; Ding, R.; Wallace, R.; Bandosz, T.

    2015-12-01

    New composite adsorbents were developed by pyrolyzing sewage sludge and fish waste (75:25 or 90:10 dry mass ratio) at 650 oC and 950 oC. Batch adsorption experiments demonstrated that the composite adsorbents were able to adsorb a wide range of organic contaminants (volatile organic compounds, pharmaceuticals and endocrine disrupting compounds (EDCs), and nitrosamine disinfection byproducts) with high capacities. Here we further examine the performance of the adsorbents for the simultaneous removal of 8 pharmaceuticals and EDCs with rapid small-scale column tests (RSSCT). Results show that the order of breakthrough in RSSCT is in general consistent with the affinity determined via batch tests. As expected, the maximum amount of adsorption for each compound obtained from RSSCT is identical to or less than that obtained from batch tests (with only one exception), due to adsorption kinetics. However, despite the very different input concentration (1 mg/L vs. 100 mg/L) and contact time (2 min empty bed contact time vs. 16 hour equilibrium time) used in RSSCT and batch tests, the maximum amount of pharmaceuticals and EDCs adsorbed under RSSCT is still about one half of that under equilibrium batch tests, validating the approach of using batch tests with much higher input concentrations to determine adsorption capacities. Results of a pilot-scale column test in a drinking water treatment plant for pharmaceuticals removal will also be presented.

  19. Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

    Schnadt, Joachim; Xu, Wei; Vang, Ronnie Thorbjørn;

    2010-01-01

    The adsorption of 2,6-naphthalenedicarboxylic acid (NDCA) molecules on the Ag(110), Cu(110), and Ag(111) surfaces at room temperature has been studied by means of scanning tunnelling microscopy (STM). Further supporting results were obtained using X-ray photoelectron spectroscopy (XPS) and soft X......-ray absorption spectroscopy (XAS). On the Ag(110) support, which had an average terrace width of only 15 nm, the NDCA molecules form extended one-dimensional (1-D) assemblies, which are oriented perpendicular to the step edges and have lengths of several hundred nanometres. This shows that the assemblies have a......-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110) surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent...

  20. The adsorption of water isotopomers on carbon adsorbents

    Adsorption isotherms in the range 50-80 Deg C were measured by gas chromatography, and isosteric adsorption heats of isotopomers of water were calculated in the range of low fillings at two activated carbons (Norit and FAS) with close volume of micropores (0.38 and 0.37 cm3/g), but various surface chemistry (AC Norit with hydrophilic surface and AC FAS with hydrophobic one). Adsorption of H2O and D2O at AC Norit exceeds adsorption at AC FAS at all equilibrium pressures. Adsorption isotherms of H2O and D2O at every adsorbents are close, but some excess of isotherms and adsorption heats of D2O as compared with H2O ones observes. It is connected with the differences in adsorbate-adsorbent and adsorbate-adsorbate interactions as well as with the structure of molecules of adsorbates

  1. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  2. Optimizing Conditions to Cholesterol Adsorbed with Carboxymethyl Chitosan

    Mardiyah Kurniasih; Dwi Kartika; Riyanti Riyanti

    2016-01-01

    A research on optimizing conditions to cholesterol adsorbed have been performed. Optimization was performed by varying: contact time, adsorbent weight and temperature of the system's. A full factorial experimental design was used in this study. Characterization performed on the synthesized chitosan and carboxymethyl chitosan including FTIR, water content, ash content, solubility, porosity, and swelling effect. The results showed that carboxymethyl chitosan able to adsorb cholesterol under con...

  3. Separation and Recovery of Tetramethyl Ammonium Hydroxide with Zeolitic Adsorbents

    S. Nishihama; Takatori, K.; K. Yoshizuka

    2010-01-01

    Separation and recovery of tetramethyl ammonium hydroxide (TMAH) has been investigated, employing several zeolites as adsorbents. Zeolite X, prepared by using TMAH as a structure directing agent, possesses highest adsorption ability among the adsorbents investigated in the present work, which corresponds to the specific surface area and pore volume of the zeolite. The adsorption amount of TMAH with the zeolitic adsorbents increases with increase in pH value in the aqueous solution, indicating...

  4. Influence of superconductor film composition on adhesion strength of coated conductors

    Kesgin, Ibrahim; Khatri, Narayan; Liu, Yuhao; Delgado, Louis; Galstyan, Eduard; Selvamanickam, Venkat

    2015-11-20

    The effect of high temperature superconductor (HTS) film composition on the adhesion strength of rare- earth barium copper oxide coated conductors (CCs) has been studied. It has been found that the mechanical integrity of the superconductor layer is very susceptible to the defects especially those along the ab plane, probably due to the weak interfaces between the defects and the matrix. Gd and Y in the standard composition were substituted with Sm and the number of in-plane defects was drastically reduced. Consequently, a four-fold increase in adhesion or peeling strength in Sm-based CCs was achieved compared to the standard GdYBCO samples.

  5. WGS-Adsorbent Reaction Studies at Laboratory Scale

    This document reports the most significant results obtained during the experimental work performed under task WGS adsorbent experimental studies within CAPHIGAS project (National Research Plan 2008-2011, ref: ENE2009-08002). The behavior of the binary adsorbent-catalyst system which will be used in the hybrid system is described in this document. Main results reported here were used during the design and development of the hybrid system adsorbent catalyst- membrane proposed in the CAPHIGAS project. The influence of main operating parameters and the optimized volume ratio adsorbent-catalyst are also presented in this report. (Author)

  6. Theoretical Insight of Physical Adsorption for a Single-Component Adsorbent + Adsorbate System: I. Thermodynamic Property Surfaces

    Chakraborty, Anutosh

    2009-02-17

    Thermodynamic property surfaces for a single-component adsorbent + adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl 2-in-silica gel + water system for cooling applications, and (ii) activated carbon (Maxsorb III) + methane system for gas storage. © Copyright 2009 American Chemical Society.

  7. Linear transport models for adsorbing solutes

    Roth, K.; Jury, W. A.

    1993-04-01

    A unified linear theory for the transport of adsorbing solutes through soils is presented and applied to analyze movement of napropamide through undisturbed soil columns. The transport characteristics of the soil are expressed in terms of the travel time distribution of the mobile phase which is then used to incorporate local interaction processes. This approach permits the analysis of all linear transport processes, not only the small subset for which a differential description is known. From a practical point of view, it allows the direct use of measured concentrations or fluxes of conservative solutes to characterize the mobile phase without first subjecting them to any model. For complicated flow regimes, this may vastly improve the identification of models and estimation of their parameters for the local adsorption processes.

  8. Nanopatterned monolayers of an adsorbed chromophore

    Frederich, N; Nysten, B; Jonas, A M [Unite de Physique et de Chimie des hauts Polymeres, Universite Catholique de Louvain, Croix du Sud 1, B-1348 Louvain-la-Neuve (Belgium); Duwez, A-S [NanoChemistry and Molecular Systems, Department of Chemistry, University of Liege, B6a Sart-Tilman, B-4000 Liege (Belgium); Muls, B; Habib-Jiwan, J-L [Unite de Chimie des Materiaux Organiques et Inorganiques, Universite Catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve (Belgium); Hofkens, J [Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Heverlee (Belgium)

    2008-08-20

    A simple lift-off process was developed to rapidly fabricate nanopatterned photofunctional surfaces. Dye molecules of a perylene derivative (PDID) were adsorbed irreversibly on clean silicon through the holes of an electron-beam lithographied polymer mask. The subsequent removal of the mask in a proper solvent results in PDID nanosized regions of width as small as 30 nm for stripes and of diameter as small as 120 nm for dots. Numerical analyses of atomic force microscopy and laser-scanning confocal microscopy images show that the dye molecules are confined to the regions defined by the lithographic process, with the integrated fluorescence intensity being essentially proportional to the size of the nanofeatures. This demonstrates that a simple organic lift-off process compatible with clean-room technology, and not involving any chemical step, is able to produce photofunctional nanopatterned surfaces, even though the dye is not chemically bonded to the silicon surface.

  9. In vitro hydroxyapatite adsorbed salivary proteins

    In spite of the present knowledge about saliva components and their respective functions, the mechanism(s) of pellicle and dental plaque formation have hitherto remained obscure. This has prompted recent efforts on in vitro studies using hydroxyapatite (HA) as an enamel model. In the present study salivary proteins adsorbed to HA were extracted with TFA and EDTA and resolved by 2D electrophoresis over a pH range between 3 and 10, digested, and then analysed by MALDI-TOF/TOF mass spectrometry and tandem mass spectrometry. Nineteen different proteins were identified using automated MS and MS/MS data acquisition. Among them, cystatins, amylase, carbonic anhydrase, and calgranulin B, were identified

  10. Rice husk as an adsorbent: A new analytical approach to determine aflatoxins in milk.

    Scaglioni, Priscila Tessmer; Badiale-Furlong, Eliana

    2016-05-15

    Aflatoxins determinations are usually expensive and employ environmentally unfriendly procedures, thus, the search for new materials and technologies, that are both ecologically safe, inexpensive and able to fulfill its role with little pre-processing is growing. One interesting approach is employing by-products as adsorbents during the extraction step of aflatoxins especially in products such as milk and dairy that are so important in basic dietary. Thus, a method to use rice husk, an agroindustry residue that is a promising material to adsorb aflatoxins to enable further analysis steps, is proposed by applying a Plackett-Burman design followed by 2(2) central composite rotational design. Rice husks were prepared by washing the husk with a solvents sequence. The washed particles were analysed by scanning electron microscopy, characterized by an elemental analyser and analysed for the presence of pesticides and mycotoxins. The rice husks contained 41% carbon, 4.3% hydrogen and 0.2% nitrogen, without mycotoxins and pesticides. The adsorptions were conducted using 0.5 g of rice husk, with 42 mesh, and 10 mL of milk contaminated with several know levels of aflatoxins M1 and B1. The solution was filtrated trough the adsorbent layer using a pressure of 10 in. Hg. The adsorbed mycotoxins were removed with 6 mL of methanol:chloroform (80:20). This condition achieved recovery of around 100% for both mycotoxins, with the average quantity of mycotoxin adsorbed equal 0.0150 µg g(-1) of afla B1 and 0.0174 µg g(-1) of afla M1. PMID:26992538

  11. Preparation and characterization of adsorbents for treatment of water associated with oil production

    Sueyoshi, Mark

    2012-09-01

    Two sets of adsorbents were prepared from locally available raw materials, characterized and tested. The first set consists of crushed natural attapulgite and crushed attapulgite mixed with petroleum tank-bottom sludge and carbonized at 650 °C. Another set was prepared using trunk of date palm tree (Phoenix dactylifera) activated at 700 and 800°C. Both sets were characterized using BET surface area and pore distributions, FTIR, XRD, SEM and TEM. Natural attapulgite and attapulgite/sludge composite exhibited different characteristics and adsorptive capacities for oil removal from oily water. Adsorptive capacities were calculated from the breakthrough curves of a column test. An oily water solution of about 500 mg-oil/L was passed through both the attapulgite and attapulgite/sludge columns until the column effluent concentration exceeded a reference limit of 10 mg-oil/L. Uptake was calculated at this limit at 155 and 405 mg-oil/g-adsorbent, respectively. This was lower than the performance of a commercial activated carbon sample (uptake calculated at 730 mg-oil/g-adsorbent). Relatively, the date palm, carbonaceous-based adsorbent samples showed less significant differences in both bulk and surface properties. Uptake significantly improved to 1330-1425 mg-oil/g-adsorbent. Attempt was made to associate this performance with the difference in the surface areas between the two sets. However, other factors are found to be important as the second set has a range of surface area less than that of the commercial sample. As evidenced by FTIR, XRD and TEM, the activated carbonaceous materials developed porous structures which form defective graphitic sheet ensembles that serve as additional adsorption sites in the sample. © 2012 Elsevier B.V.

  12. Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

    Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

    2010-01-01

    Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced and the...... effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

  13. Thermodynamic study of fatty acids adsorption on different adsorbents

    This work has as objective the study about the adsorption behavior of fatty acids (acetic, propionic, and butyric) on activated carbon and on modified and unmodified montmorillonite clays as a function of temperature and initial concentration of the adsorbate, through adsorption isotherms and their thermodynamic parameters (ΔG, ΔH, and ΔS). The activated carbon presented a higher adsorption capacity due to its relatively large surface area, compared to others adsorbents. The polar characteristic of fatty acids decreased with the increase in the length of non-polar hydrocarbon chain, improving the affinity between the activated carbon (non-polar adsorbent) and the acids. The adsorption capacity of modified montmorillonite (polar adsorbent) was favored due to the presence of the organic cation among its layers, which make the surface more hydrophobic and organophilic when compared to the unmodified montmorillonite surface. The amount of fatty acids adsorbed in the adsorbents surface increased with the concentration, at constant temperature, and decreased with the increase of temperature, at constant concentration. The amount of fatty acids adsorbed in the three adsorbents was related to the surface area and polarity of the adsorbent, concentration and solubility of the adsorbate and temperature of the solution. The negative values of ΔG and ΔH showed that the adsorption on activated carbon and on modified and unmodified montmorillonite clays was a spontaneous and an exothermic process. The decrease in the values of ΔG, with the increase of temperature, demonstrated that the adsorption was benefited by the high temperature and the positive values of ΔS showed that the fatty acids molecules were in a more randomic condition in the adsorbed state than in solution. The experimental results obtained at the temperatures of (298, 303, 313, and 323) K showed that experimental data were well represented by the Langmuir and Freundlich isotherms models

  14. NOx Removal and Effect of Adsorbate-Adsorbate Interactions

    Khan, Tuhin Suvra

    industrial chemical processes, nano-science and nano-technology, in general any process where a solid surface interacts with any surrounding liquid or gas-phase species. Computational approaches play an increasingly important role in modern surface science, and density functional theory (DFT) in particular......-standing dream of an environmentally sustainable energy sector is to be fulfilled, heterogeneous catalysts aiding production, storage, and use of energy from sustainable sources, e.g. sunlight, wind, and biomass, are expected to be essential. New catalysts improving the efficiency of existing chemical processes...... have analyzed these challenges systematically and have developed some new methods and models to counter those challenges and obtain some general understanding of the catalytic process. I have developed an adsorbate-adsorbate interaction model to include the coverage dependency of the adsorption energy...

  15. Application of bifunctional magnetic adsorbent to adsorb metal cations and anionic dyes in aqueous solution

    Lin, Ya-Fen [Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 260, Taiwan (China); Chen, Hua-Wei [Department of Cosmetic Application and Management, St. Mary' s Medicine Nursing and Management College, I-Lan, Taiwan (China); Chien, Poh-Sun [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Chiou, Chyow-San, E-mail: cschiou@niu.edu.tw [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China); Liu, Cheng-Chung [Department of Environmental Engineering, National I-Lan University, 1, Sec. 1, Shen-Lung Road, I-Lan, 260, Taiwan (China)

    2011-01-30

    A magnetic adsorbent, amine-functionalized silica magnetite (NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4}), has been synthesized to behave as an anionic or cationic adsorbent by adjusting the pH value of the aqueous solution to make amino groups protonic or neutral. NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were used to adsorb copper ions (metal cation) and Reactive Black 5 (RB5, anionic dye) in an aqueous solution in a batch system, and the maximum adsorption were found to occur at pH 5.5 and 3.0, respectively. The adsorption equilibrium data were all fitted the Langmuir isotherm equation reasonably well, with a maximum adsorption capacity of 10.41 mg g{sup -1} for copper ions and of 217 mg g{sup -1} for RB5. A pseudo-second-order model also could best describe the adsorption kinetics, and the derived activation energy for copper ions and RB5 were 26.92 kJ mol{sup -1} and 12.06 kJ mol{sup -1}, respectively. The optimum conditions to desorb cationic and anionic adsorbates from NH{sub 2}/SiO{sub 2}/Fe{sub 3}O{sub 4} were provided by a solution with 0.1 M HNO{sub 3} for copper ions and with 0.05 M NaOH for RB5.

  16. Structural characterization and thermal analysis of 4 A and 5 A zeolite adsorbents

    Adsorption processes are widely used in the industries, both for purification and for bulk separation. The discovery and commercialization of synthetic zeolites as adsorption provide a major stimulus to the development of adsorption as a separation process. The primary requirement for development of an adsorption separation process using zeolite is the structural characterization of the material. The most important analysis include the evaluation of pore volume, pore size distribution, surface area and density. This paper describes commercial zeolitic adsorbents, its structure and the methods applied to its characterization. They work also an experimental study where different analytical techniques were used to determine the physical properties, chemical composition and crystalline structure for type 4A zeolitic adsorbents. (author)

  17. Film morphology and orientation of amino silicone adsorbed onto cellulose substrate

    A series of amino silicones with different amino values were synthesized and adsorbed onto surfaces of cotton fibers and cellulose substrates. The film morphology, hydrophobic properties and surface composition of the silicones are investigated and characterized by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), contact angle measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared (ATR-IR). The results of the experiments indicate that the amino silicone can form a hydrophobic film on both cotton fibers and cellulose substrates and reduce the surface roughness significantly. Furthermore, the roughness becomes smaller with an increase in the amino value. All these results suggest that the orientation of amino silicone molecule is with the amino functional groups of amino silicone molecule adsorbed onto the cellulose interface while the main polymer chains and the hydrophobic Si-CH3 groups extend toward the air.

  18. Effects of ambient conditions on adsorbed surfactant and polymer monolayers

    The physical properties of surfactant-coated and polyelectrolyte-coated surfaces in adhesive contact in air have been studied using the surface forces apparatus technique. Various physisorbed monolayers with different head groups and chains (or polymer segments) were prepared both by adsorption form solution (self-assembly) and by the Langmuir-Blodgett deposition technique. The results show that many monolayer properties depend on the atmospheric conditions such as the relative humidity or presence of organic vapors and that these properties can further change when two monolayer-coated surfaces are brought into contact. These properties include monolayer composition and structure, thickness and compressibility, fluidity and phase state (i.e., whether solid, gel, or liquid), and the adhesion between two monolayer-coated surfaces. In addition, we find that both out-of-plane and in-plane (lateral) phase transitions can be induced in certain adsorbed monolayers when they are subjected to a compressive stress. The results provide new insights into molecular ordering and dynamics in physisorbed monolayers and how monolayers are affected when they are exposed to vapors or when they interact with other surfaces. 18 refs., 13 figs., 4 tabs

  19. Single bank NOx adsorber for heavy duty diesel engines

    Genderen, M. van; Aken, M.G. van

    2003-01-01

    In a NOx adsorber programme the feasibility for applying this technology to heavy duty diesel engines was investigated. After modelling and simulations for realising best λ < 1 engine conditions a platform was build which was used to obtain good NOx adsorber regeneration settings in a number of stea

  20. Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite.

    Mishael, Yael Golda; Undabeytia, Tomas; Rytwo, Giora; Papahadjopoulos-Sternberg, Brigitte; Rubin, Baruch; Nir, Shlomo

    2002-05-01

    The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption of hexadecyltrimethylammonium (HDTMA) and octadecyltrimethylammonium (ODTMA) on montmorillonite was studied above and below their critical micelle concentrations (CMC). At concentrations above the CMC, the loading exceeded the clay's cation exchange capacity (CEC) and indicated higher affinity of the cation with the longer alkyl chain. An adsorption model could adequately simulate adsorption at concentrations below the CMC, and yield fair predictions for the effect of ionic strength. The model indicated that above the CMC adsorbed micelles contributed significantly to the amount of ODTMA adsorbed. Evidence for adsorption of ODTMA micelles on montmorillonite was provided by X-ray diffraction, freeze-fracture electron microscopy, and dialysis bag measurements. SFM was not adsorbed directly on the clay mineral, and adsorbed at low levels, when the organic cation was adsorbed as monomers. In contrast, a large fraction of SFM adsorbed on the clay mineral when incorporated in micelles that adsorbed on the clay. PMID:11982411

  1. A nuclear standard high-efficiency adsorber for iodine

    The structure of a nuclear standard high-efficiency adsorber, adsorbent and its performance are introduced. The performance and structure were compared with the same kind product of other firms. The results show that the leakage rate is less than 0.005%

  2. Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

    Shubo DENG; Danmeng SHUAI; Qiang YU; Jun HUANG; Gang YU

    2009-01-01

    Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics,isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS On the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

  3. Synthesis and properties of porous zeolite aluminosilicate adsorbents

    Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined

  4. Structure and properties of water film adsorbed on mica surfaces

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  5. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  6. Rod-like cyanophenyl probe molecules nanoconfined to oxide particles: Density of adsorbed surface species

    Frunza, Stefan; Frunza, Ligia; Ganea, Constantin Paul; Zgura, Irina; Brás, Ana Rita; Schönhals, Andreas

    2016-02-01

    Surface layers have already been observed by broadband dielectric spectroscopy for composite systems formed by adsorption of rod-like cyanophenyl derivates as probe molecules on the surface of oxide particles. In this work, features of the surface layer are reported; samples with different amounts of the probe molecules adsorbed onto oxide (nano) particles were prepared in order to study their interactions with the surface. Thermogravimetric analysis (TGA) was applied to analyze the amount of loaded probe molecules. The density of the surface species ns was introduced and its values were estimated from quantitative Fourier transform infrared spectroscopy (FTIR) coupled with TGA. This parameter allows discriminating the composites into several groups assuming a similar interaction of the probe molecules with the hosts of a given group. An influence factor H is further proposed as the ratio of the number of molecules in the surface layer showing a glassy dynamics and the number of molecules adsorbed tightly on the surface of the support: It was found for aerosil composites and used for calculating the maximum filling degree of partially filled silica MCM-41 composites showing only one dielectric process characteristic for glass-forming liquids and a bulk behavior for higher filling degrees.

  7. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T. [ORNL; Saito, Tomonori [ORNL; Brown, Suree [ORNL; Gill, Gary [PNNL; Kuo, Li-Jung [PNNL; Wood, Jordana [PNNL

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  8. Neutron reflectivity study of adsorbed diblock copolymers

    This paper summarizes our cumulative work on neutron reflectivity studies of polystyrene-poly(vinyl-2-pyridine) (PS-PVP) and polystyrenepolyethylene oxide (PS-PEO) adsorbed at a quartz-solvent interface. Deuterated toluene was chosen as the solvent since it is a good solvent for PS and a poor one for either of the other two blocks. In this case, the polystyrene dangles into the solvent while the other block acts as an anchor. The neutron reflectivity studies reveal that the form of the polymer density profile normal to the substrate may be varied from an extended ''brush'' to a condensed ''mushroom'' conformation by manipulating the ratio of the molecular weights of the two blocks. In addition, we present new data on the PS-PEO system in a poor solvent, deuterated cyclohexane, under conditions of shear flow in Poiseuille geometry. We find that when the PS-PEO diblock is absorbed from cyclohexane and is allowed to relax, the PS chain takes on a ''mushroom'' conformation. However, when the shear is applied, the layer shear thickens due to the PS chains extended to nearly twice their original lengths

  9. Surface characterization of Ag/Titania adsorbents

    Samokhvalov, Alexander; Nair, Sachin; Duin, Evert C.; Tatarchuk, Bruce J.

    2010-03-01

    The Ag/Titania adsorbent for selective removal of the desulfurization-refractive polycyclic aromatic sulfur heterocycles (PASHs) from liquid hydrocarbon fuels was prepared, its total and the Ag specific surface area were determined and the surface reaction sites in the sorbent that may be active in the adsorptive selective desulfurization were characterized by several spectroscopic and surface science techniques. The sorbent contains Ag, Ti, O and spurious C on its surface, as by the XPS measurements. Silver is present as an oxide, as judged by the XPS Auger parameter (AP). The complementary electron spin resonance (ESR) spectroscopy confirms that the majority of Ag is present in the diamagnetic Ag 1+ form, with the minor concentration (˜0.1% of total Ag) present as Ag 2+. The findings by XPS and ESR are confirmed by the XRD, UV-vis spectroscopy and thermodynamic considerations. The supported Ag is highly dispersed on the surface of the titania support, with the particle size of ˜30-60 Å depending on Ag content, with an Ag specific surface area of ˜7-14 m 2/g, vs. the total surface area of ˜114-58 m 2/g.

  10. Pyrolyzed feather fibers for adsorbent and high temperature applications

    Senoz, Erman

    Chicken feather fibers (CFF) are problematic and costly for the poultry industry in terms of managing maintenance and disposal. Considering their great availability, low cost, and unique protein structure, CFF can be an environmentally friendly and bio-renewable candidate to replace petroleum products. CFF's low degradation and melting temperature render them useless at high temperatures. Pyrolysis methods were developed for CFF by using two temperature steps to convert them into high temperature resistant and adsorbent fibers while retaining their original physical appearance and affine dimensions. An intermolecular crosslinking mechanism in the first step of pyrolysis at 215 ºC for 24 h provided an intact fibrous structure with no subsequent melting. The evidence obtained from the thermal, bulk, and surface analysis techniques was indication of the simultaneous side chain degradation, polypeptide backbone scission, disulfide bond cleavage, and isopeptide crosslinking. The variation in the reaction kinetics of disulfide bond cleavage and isopeptide crosslinking played an important role in the melting transition. Consequently, long-lasting heat treatments below the melting point provided sufficient crosslinks in the protein matrix to keep the fibrous structure intact. Water-insoluble and crosslinked CFF reinforced the triglyceride-fatty acid based composites by providing a 15 fold increase in storage and tensile modulus at room temperature. These thermally stable fibers can be used instead of CFF in composites which may require high temperature compounding and molding processes. The second step of pyrolysis at 400--450 ºC for 1 h resulted in microporous fibers with a micropore volume of ˜0.18 cm3/g STP and with a narrower pore size distribution than commercial activated carbons through thermal degradation. Nearly all accessible pores in the microporous pyrolyzed chicken feather fibers (PCFF) had diameters less than 1 nm and therefore, showed a potential to be

  11. A theoretical study of adsorbate-adsorbate interactions on Ru(0001)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    barrier for dissociation, whereas S will increase it. The interaction with alkali atoms is mainly of an electrostatic nature. The poisoning by S is due to two kinds of repulsive interactions: a Pauli repulsion and a reduced covalent bond strength between the adsorbate and the surface d-electrons. In order...... to investigate these different interactions in more detail, we look at three different species (N atoms, and terminally bonded N(2) and CO) and use them as probes to study their interaction with two modifier atoms (Na and S). The two modifier atoms have very different properties, which allows us to...

  12. Filter for high temperature water coated with ion adsorbent

    The surface of filters is covered with ion adsorbents comprising compound oxides consisting of 50 to 70 wt% of iron or nickel and 30 to 50 wt% of titanium. Cooling water at high temperature and high pressure flows from an entrance nozzle and reaches the filters coated with the ion adsorbents, where ionic corrosion products are adsorbed and removed. Then, in the course of passing through porous fine sintered metal tubes, granular corrosion products contained in the cooling water are filtered and removed. This enables to directly clean-up reactor coolants at high temperature and high pressure. (Y.Y.)

  13. Effect of ZrO{sub 2} particle on the performance of micro-arc oxidation coatings on Ti6Al4V

    Li, Hong; Sun, Yezi; Zhang, Jin, E-mail: zhangjin@ustb.edu.cn

    2015-07-01

    Highlights: • An anti-oxidation TiO{sub 2}/ZrO{sub 2} composite coating on Ti6Al4V alloy was prepared using micro-arc oxidation technology by adding ZrO{sub 2} particles in single phosphoric acid solution. • The composite coating displays excellent anti-oxidation characteristic at 700 °C in the air. • The concentration of ZrO{sub 2} particles not only influences the roughness and thickness of the coating, but the morphologies, phase composition, oxidation resistance and wear resistance. - Abstract: This paper investigates the effect of ZrO{sub 2} particle on the oxidation resistance and wear properties of coatings on a Ti6Al4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations micron ZrO{sub 2} particles were added in phosphate electrolyte and dispersed by magnetic stirring apparatus. The composition of coating was characterized using X-ray diffraction and energy dispersive spectrum, and the morphology was examined using SEM. The high temperature oxidation resistance of the coating sample at 700 °C was investigated. Sliding wear behaviour was tested by a wear tester. The results showed that the coating consisted of ZrTiO{sub 4}, ZrO{sub 2}, TiO{sub 2}. With ZrO{sub 2} particle addition, the ceramic coating's forming time reduced by the current dynamic curve. It was shown that the addition of ZrO{sub 2} particles (3 g/L, 6 g/L) expressed an excellent oxidation resistance at 700 °C and wear resistance.

  14. Interaction of PC-3 cells with fibronectin adsorbed on sulfonated polystyrene surfaces

    Hanna M. Kowalczyńska

    2012-01-01

    Full Text Available The ability of cancer cells to invade neighboring tissues is crucial for cell dissemination and tumor metastasis. It is generally assumed that cell adhesion to extracellular matrix proteins is an important stage of cancer progression. Hence, adhesion of cancer cells under in vitro conditions to proteins adsorbed on a substratum surface has been studied to provide a better understanding of cell-protein interaction mechanisms. A protein, adsorbed in an appropriate conformation on a substratum surface, creates a biologically active layer that regulates such cell functions as adhesion, spreading, proliferation and migration. In our study, we examined the interaction of PC-3 cells under in vitro conditions with fibronectin adsorbed on sulfonated polystyrene surfaces of a defined chemical composition and topography. We investigated cell adhesion to fibronectin and cell spreading. Using automatic, sequential microscopic image registration, we are the first to present observations of the dynamics of PC-3 cell spreading and the cell shape during this process. Our results show that cell adhesion and the shape of spreading cells strongly depend on the time interaction with fibronectin. The analysis of images of cytoskeletal protein distribution in the cell region near the cell-substratum interface revealed that induction of a signal cascade took place, which led to the reorganization of the cytoskeletal proteins and the activation of focal adhesion kinase (FAK. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 4, pp. 706–718

  15. Dynamics of CO 2 Adsorption on Amine Adsorbents. 2. Insights Into Adsorbent Design

    Bollini, Praveen

    2012-11-21

    Packed bed breakthrough experiments are reported for commercial zeolite 13X and 3-aminopropyl-functionalized SBA-15 silica materials with three different amine loadings. Mass and heat transfer dynamics for all four materials are modeled successfully. Amine adsorbents with open pores are found to exhibit faster mass diffusion rates compared to zeolite 13X. When amine loading is increased by coupling aminopropyl groups, premature breakthrough combined with a long tail is observed. Contrary to conventional physisorbants, finite heat losses to the column wall do not explain the long breakthrough tail. A rate model that accounts for heterogeneity in diffusion was found to accurately capture the breakthrough shape of the high loading material. Batch uptake measurements support the hypothesis that slow diffusion through the polymer phase is what hampers adsorption kinetics in the high amine loading adsorbent. The results emphasize the importance of designing materials that are not overloaded with amine sites, as excessive amine loadings can lead to depressed adsorption kinetics and premature column breakthrough. © 2012 American Chemical Society.

  16. Application of a new adsorbent for fluoride removal from aqueous solutions

    Srivastav, Arun Lal [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Singh, Prabhat K. [Department of Civil Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Srivastava, Varsha [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Sharma, Yogesh C., E-mail: ysharma.apc@itbhu.ac.in [Department of Applied Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2013-12-15

    Highlights: • A new adsorbent has been prepared. • The adsorbent is non-toxic and easy to synthesize. • HBO{sub 1} has displayed best capacity for the removal of fluoride. • Unlike most adsorbents, HBO{sub 1} is suitable for the removal of fluoride from water. • The process of removal has been optimized. -- Abstract: Hydrous bismuth oxides (HBOs) have been investigated as a possible adsorbent for fluoride removal from water. Apart from bismuth trioxide (Bi{sub 2}O{sub 3}) compound, three additional HBOs, named as HBO{sub 1}, HBO{sub 2}, and HBO{sub 3} were synthesized in the laboratory and examined for their relative potentials for fluoride removal from aqueous solutions. HBO{sub 1} was observed to have highest fluoride removal at 10 mg/L initial concentration in aqueous environment. Among competitive anions, sulfate and chloride affect the fluoride removal by HBO{sub 1} more adversely than bicarbonate. Characterization of HBOs using X-ray diffraction (XRD) pattern analyses indicated crystalline structures, and the broad chemical composition of materials showed successive increase of Bi(OH){sub 3} from HBO{sub 1} to HBO{sub 3}, with decrease of BiOCl in the same order. Fourier Transform Infrared (FTIR) spectroscopy analyses indicated presence of Bi-O bond and successively increasing number of peaks corresponding to OH ion from HBO{sub 1} to HBO{sub 3}. Scanning Electron Microscopic (SEM) images of HBOs show rough and porous structure of the materials. Presence of higher proportion of chloride compound in HBO{sub 1} with respect to others appears to be the factor responsible for its better performance in fluoride removal from aqueous solutions.

  17. Application of a new adsorbent for fluoride removal from aqueous solutions

    Highlights: • A new adsorbent has been prepared. • The adsorbent is non-toxic and easy to synthesize. • HBO1 has displayed best capacity for the removal of fluoride. • Unlike most adsorbents, HBO1 is suitable for the removal of fluoride from water. • The process of removal has been optimized. -- Abstract: Hydrous bismuth oxides (HBOs) have been investigated as a possible adsorbent for fluoride removal from water. Apart from bismuth trioxide (Bi2O3) compound, three additional HBOs, named as HBO1, HBO2, and HBO3 were synthesized in the laboratory and examined for their relative potentials for fluoride removal from aqueous solutions. HBO1 was observed to have highest fluoride removal at 10 mg/L initial concentration in aqueous environment. Among competitive anions, sulfate and chloride affect the fluoride removal by HBO1 more adversely than bicarbonate. Characterization of HBOs using X-ray diffraction (XRD) pattern analyses indicated crystalline structures, and the broad chemical composition of materials showed successive increase of Bi(OH)3 from HBO1 to HBO3, with decrease of BiOCl in the same order. Fourier Transform Infrared (FTIR) spectroscopy analyses indicated presence of Bi-O bond and successively increasing number of peaks corresponding to OH ion from HBO1 to HBO3. Scanning Electron Microscopic (SEM) images of HBOs show rough and porous structure of the materials. Presence of higher proportion of chloride compound in HBO1 with respect to others appears to be the factor responsible for its better performance in fluoride removal from aqueous solutions

  18. TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER

    RAISA NASTAS

    2012-03-01

    Full Text Available Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O, or metals (Fe, Cu, Ni, on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions.

  19. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  20. SUPERCRITICAL FLUID EXTRACTION OF PARTICULATE AND ADSORBENT MATERIALS

    The report is a summary of work performed by PNL on the extraction of semivolatile organic materials (SVOCs), for example, polynuclear aromatic compounds, from various adsorbents and environmental matrices, using supercritical fluids (SCFs) as extractants. The results of the work...

  1. Low Pressure Adsorbent for Recovery & Storage Vented Hydrogen Project

    National Aeronautics and Space Administration — A high performance fullerene-based adsorbent is proposed for recovery and storage hydrogen and separating helium via pressure-swing-adsorption (PSA) process....

  2. Large-scale separation of magnetic bioaffinity adsorbents

    Šafařík, Ivo; Ptáčková, Lucie; Šafaříková, Miroslava

    2001-01-01

    Roč. 23, - (2001), s. 1953-1956. ISSN 0141-5492 Institutional research plan: CEZ:AV0Z6087904 Keywords : magnetic adsorbents * magnetic separation Subject RIV: EI - Biotechnology ; Bionics Impact factor: 0.915, year: 2001

  3. Synthesis and uranium adsorption behavior of alginate-based adsorbents

    The crosslinked microspheres of alginate were synthesized by inverse suspension polymerization, and the effect of the concentration of sodium alginate solution and stirring speed on the formation of microsphere was studied. Biopolymeric adsorbents with amidocyanogen were synthesized based on alginate polymeric matrixes by chemical modification. The adsorbents were characterized by FTIR and determination of ammonio content. When the concentration of sodium alginate solution was 3%-4% and stirring speed was 250-300 r/min, the crosslinked microsphere had regular morphology and high mechanical strength. Uranium can be removed effectively from low concentration uranium solutions by the alginate-based adsorbent (SATT) modified with triethylenetetreamine, and the removal rate was more than 92%. The adsorbent was expected to use for wastewater treatment in uranium hydrometallurgy. (authors)

  4. Development of novel adsorbents for environmental cleaning by radiation

    In order to improve our amenity spaces, the demand of non-odorous atmosphere is needed. Toxic gases such as trimethylamine and ammonia have been treated as the pollutant of the atmosphere. The development of an excellent and effective adsorbent for the toxic gases has been performed here and there all over the world. However, the development of the adsorbent with the consideration for conservation of environment must be made as one of the requisites. Therefore, we proposed the use of radiation for the preparation of toxic-gas-adsorbing materials. On the other hand, in our daily life, the large amount of calcium and magnesium contained in our drinking water has hindered the removal of a trace amount of pollutant such as lead. As a result, the development of the metal-ion-adsorbing material is very indispensable indeed. (J.P.N.)

  5. Adsorption of remazol brilliant blue on an orange peel adsorbent

    M. R. Mafra

    2013-09-01

    Full Text Available A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. The time to reach equilibrium was 15 h for the concentration range of 30 mg L-1 to 250 mg L-1. The adsorption capacity decreased with increasing temperature, from 9.7 mg L-1 at 20 ºC to 5.0 mg L-1 at 60 ºC. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated.

  6. Development of solid adsorbent materials for CO₂capture

    Ogbuka, Chidi Premie

    2013-01-01

    The application of solid adsorbents for gas separation in pre-combustion carbon capture from gasification processes has gained attention in recent times. This is due to the potential of the technology to reduce the overall energy penalty associated with the capture process. However, this requires the development of solid adsorbent materials with large selectivity, large adsorption capacity, fast adsorption kinetics for CO2 coupled with good mechanical strength and thermal stability. In this ...

  7. Electronic and electrochemical doping of graphene by surface adsorbates

    Hugo Pinto; Alexander Markevich

    2014-01-01

    Many potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed...

  8. Enhancement of dissolution profile of gliclazide by solid dispersion adsorbates

    Singh, Narender; Arora, Ashish; Kaushik, Deepak

    2011-01-01

    This article investigates enhancement of the dissolution profile of gliclazide, an antidiabetic drug, using the combination of solid dispersions and melt adsorption techniques. Poloxamer and PEG 6000 were utilized as hydrophilic carriers for solid dispersions preparation and lactose selected on the basis of preliminary studies was utilized as an adsorbent for the preparation of solid dispersion adsorbates. The techniques of FTIR spectroscopy, differential scanning calorimetry (DSC), and X-ray...

  9. Residence time determination for adsorbent beds of different configurations

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  10. THE USE OF LOW COST ADSORBENTS FOR PURIFICATION WASTEWATER

    Višekruna, Antonija; Štrkalj, Anita; Marinić Pajc, Ljiljana

    2011-01-01

    Adsorption is one of the effective methods of advanced wastewater treatment, which industries employ to reduce hazardous organic and inorganic wastes in effluents. The use of low cost adsorbent has been investigated as a replacement for current costly methods of removing toxic substances from wastewater. In this article, the use of low cost adsorbents for the removal of toxic substances from wastewater has been reviewed.

  11. Development of an adsorbent for both cesium and strontium

    Described is the development of the adsorbent in the title at the process of developing the agent to adsorb each element. For cooling the reactors injured by the Fukushima Nuclear Power Plant Accident by the earthquake and tsunami on the day before (Mar. 11, 2011), fresh/ sea water is supplied in the reactor and flows out contaminated with radioactive elements in the turbine building and then in the treatment plant to remove oil and cesium for re-circulation to the reactor. Water from the plant still contains radioisotopes derived from fission, like 90Sr/90Y at 1.2 x 108 Bq/L and 137Cs/137mBa at 6.1 x 103 Bq/L, and from activation of reactor materials. Before the plant, the water contains 137Cs at the level as high as 4.1 x 107 Bq/L. Authors have examined various agents to adsorb 90Sr and 137Cs with a measure of partition coefficient Kd (L of the artificial sea water/kg) and have come to find out the adsorbent in the title: it is derived from the Cs-adsorbing crystalized silico-titanate (CST). The adsorbent is obtainable by surface treatment of CST with NaOH and has high Kds of >1 x 103 and >1 x 104 L/kg for Sr and Cs, respectively, while other ordinary adsorbents' Kds are: artificial zeolite 1-10 x 102/1-10 x 101 for Sr/Cs, respectively; natural one 0.1-10 x 101/1-10 x 102; ferrocyanide 0.1-10 x 101/1-10 x 104, and CST 1 x 101/>1 x 104. When 1 m3 of the present adsorbent is used, >99% of Cs and Sr can be removable in >3,000 m3 of contaminated water, suggesting its usefulness for dealing with water after the Accident. (T.T.)

  12. Vanadium (4) complexing in phase of adsorbent with benzimidazole groups

    Equilibrium and kinetic characteristics of V4+ sorption by POLYORGS XI-H adsorbent with benzimidazole groups (BIm) are investigated. Using ESR method it is stated that [VO2+]:[BIm]1:2 complex, where VO2+ is combined with nitrogen atoms of two imidazole groups, is formed in adsorbent phase. The highest distribution factor of 4.7x103 is attained at pH6

  13. Plant waste materials from restaurants as the adsorbents for dyes

    Pavlović Marija D.; Nikolić Ivan R.; Milutinović Milica D.; Dimitrijević-Branković Suzana I.; Šiler-Marinković Slavica S.; Antonović Dušan G.

    2015-01-01

    This paper has demonstrated the valorization of inexpensive and readily available restaurant waste containing most consumed food and beverage residues as adsorbents for methylene blue dye. Coffee, tea, lettuce and citrus waste have been utilized without any pre-treatment, thus the adsorption capacities and dye removal efficiency were determined. Coffee waste showed highest adsorbent capacity, followed by tea, lettuce and citrus waste. The dye removal was mo...

  14. Efforts to Consolidate Chalcogels with Adsorbed Iodine

    Riley, Brian J.; Pierce, David A.; Chun, Jaehun

    2013-08-28

    This document discusses ongoing work with non-oxide aerogels, called chalcogels, that are under development at the Pacific Northwest National Laboratory as sorbents for gaseous iodine. Work was conducted in fiscal year 2012 to demonstrate the feasibility of converting Sn2S3 chalcogel without iodine into a glass. This current document summarizes the work conducted in fiscal year 2013 to assess the consolidation potential of non-oxide aerogels with adsorbed iodine. The Sn2S3 and Sb13.5Sn5S20 chalcogels were selected for study. The first step in the process for these experiments was to load them with iodine (I2). The I2 uptake was ~68 mass% for Sn2S3 and ~50 mass% for Sb13.5Sn5S20 chalcogels. X-ray diffraction (XRD) of both sets of sorbents showed that metal-iodide complexes were formed during adsorption, i.e., SnI4 for Sn2S3 and SbI3 for Sb13.5Sn5S20. Additionally, metal-sulfide-iodide complexes were formed, i.e., SnSI for Sn2S3 and SbSI for Sb13.5Sn5S20. No XRD evidence for unreacted iodine was found in any of these samples. Once the chalcogels had reached maximum adsorption, the consolidation potential was assessed. Here, the sorbents were heated for consolidation in vacuum-sealed quartz vessels. The Sb13.5Sn5S20 chalcogel was heated both (1) in a glassy carbon crucible within a fused quartz tube and (2) in a single-containment fused quartz tube. The Sn2S3 chalcogel was only heated in a single-containment fused quartz tube. In both cases with the single-containment fused quartz experiments, the material consolidated nicely. However, in both cases, there were small fractions of metal iodides not incorporated into the final product as well as fused quartz particles within the melt due to the sample attacking the quartz wall during the heat treatment. The Sb13.5Sn5S20 did not appear to attack the glassy carbon crucible so, for future experiments, it would be ideal to apply a coating, such as pyrolytic graphite, to the inner walls of the fused quartz vessel to prevent

  15. One-pot synthesis of a graphene oxide coated with an imprinted sol–gel for use in electrochemical sensing of paracetamole

    A route is described for the preparation of a composite consisting of graphene oxide and a molecularly imprinted sol–gel polymer (GO/MIPs) through one-pot room temperature polymerization in aqueous solution. The material was obtained by mixing graphene oxide with the monomers (phenyltriethoxysilane and tetramethoxysilane) and the template paracetamole, followed by sol–gel copolymerization and extraction. The monomer and template concentrations and the incubation time were optimized. The composite was characterized by FTIR, TGA, XRD, Raman spectroscopy and SEM. It was then deposited as a thin film acting as a molecular recognition element on a glassy carbon electrode to obtain an electrochemical sensor for paracetamole. The electrode displayed an excellent recognition capacity toward paracetamole compared to its analogs. The peak current is linearly proportional to the concentration of paracetamole in the 0.1 μM to 80 μM range, and the detection limit is 20 nM (at an SNR of 3). Hence, this electrode possesses a wider response range and lower detection limit compared to most previously reported electrochemical sensors for paracetamole. It also exhibits excellent stability and has been successfully used to determine paracetamole in tablets and spiked human urine samples. (author)

  16. Cryogenic adsorber design in a helium refrigeration system

    Hu, Zhongjun; Zhang, Ning; Li, Zhengyu; Li, Q.

    2012-06-01

    The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorber's maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of the adsorber are designed. The mass transfer length should be taken into account in the adsorber height design. The pressure decrease is also calculated. The important factors that influence the adsorber pressure decrease are the void tower speed, the adsorbed layer height, and the active carbon particle shape and size.

  17. Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

    Shibata, Takuya; Seko, Noriaki; Amada, Haruyo; Kasai, Noboru; Saiki, Seiichi; Hoshina, Hiroyuki; Ueki, Yuji

    2016-02-01

    A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8-8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

  18. Optimizing Conditions to Cholesterol Adsorbed with Carboxymethyl Chitosan

    Mardiyah Kurniasih

    2016-05-01

    Full Text Available A research on optimizing conditions to cholesterol adsorbed have been performed. Optimization was performed by varying: contact time, adsorbent weight and temperature of the system's. A full factorial experimental design was used in this study. Characterization performed on the synthesized chitosan and carboxymethyl chitosan including FTIR, water content, ash content, solubility, porosity, and swelling effect. The results showed that carboxymethyl chitosan able to adsorb cholesterol under conditions optimal adsorbent with cholesterol ratio (1:200 with a contact time of 90 minutes at temperature of 40 °C. Meanwhile, at a temperature of 55 °C carboxymethyl chitosan capable of adsorb cholesterol under conditions optimal adsorbent with cholesterol ratio (1:300 with a contact time of 30 minutes. Chitosan and carboxymethyl chitosan synthesized has a water content of 7.4 and 10.2%, ash content of 0.14 and 2.29%, solubility in distilled water at 1.10-5and 1.98.10-3%, solubility in acetic acid 0.02 and 0.04%, porosity at 88.3% and 88.8%, and swelling at 163.13 and 182.98%.

  19. Application of Silver Impregnated Iodine Adsorbent to Nuclear Facilities

    Fukasawa, Tetsuo; Nakamura, Tomotaka; Kondo, Yoshikazu; Funabashi, Kiyomi

    Radioactive iodine is one of the most important nuclides to be prevented for release from nuclear facilities and many facilities have off-gas treatment systems to minimize the volatile nuclides dispersion to the environment. Silver impregnated inorganic adsorbents were known as inflammable and stable fixing materials for iodine and the authors started to develop 25 years ago a kind of inorganic adsorbent that has better capability compared with conventional ones. Aluminum oxide (Alumina) was selected as a carrier material and silver nitrate as an impregnated one. Pore diameters were optimized to avoid the influence of impurities such as humidity in the off-gas stream at lower temperatures. Experiments and improvements were alternately conducted for the new adsorbent. The tests were carried out in various conditions to confirm the performance of the developed adsorbent, which clarified its good ability to remove iodine. Silver nitrate impregnated alumina adsorbent (AgA) has about twice the capacity for iodine adsorption and higher iodine removal efficiency at relatively high humidity than conventional ones. The AgA chemically and stably fixes radioactive iodine and fits the storage and disposal of used adsorbent. AgA is now and will be applied to nuclear power plants, reprocessing plants, and research facilities.

  20. Gold recovery from low concentrations using nanoporous silica adsorbent

    Aledresse, Adil

    The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The

  1. Effect of heat-treatment on phase formation and crystallization of sol–gel derived Al2O3, ZrO2–Y2O3, and Ta2O5 oxide coatings

    Yang-Il Jung

    2015-06-01

    Full Text Available Various oxides of Al2O3, ZrO2–Y2O3, and Ta2O5 were coated on ferritic–martensitic steel for application as an environmental barrier layer. Sol–gel based coating was investigated to form the oxides by varying the coating parameters, such as the concentration of the precursors, the temperature of the curing, cycles of repeated runs, and additional heat-treatment. The obtained coatings revealed nano-sized granular structures. The surface morphologies were rough in alumina and zirconia, but appeared smooth in tantalum oxide. In the case of alumina and tantalum oxide, coated layers were mostly amorphous after pyrolysis at 750 °C. The crystalline phases were obtained after an additional heat-treatment at 950 °C. In the case of zirconia, a desirable oxide phase was formed when the samples were cured at 750 °C during the coating process. In addition to the heat-treatment after the coating, the repeated coatings were effective in crystallizing the coated layers and forming proper oxides.

  2. Utility of adsorbents in the purification of drinking water: a review of characterization, efficiency and safety evaluation of various adsorbents.

    Dubey, Shashi Prabha; Gopal, Krishna; Bersillon, J L

    2009-05-01

    Clean drinking water is one of the implicit requisites fora healthy human population. However the growing industrialization and extensive use of chemicals for various concerns, has increased the burden of unwanted pollutants in the drinking water of developing countries like India. The entry of potentially hazardous substances into the biota has been magnifying day by day. In the absence of a possible stoppage of these, otherwise, useful chemicals, the only way to maintain safer water bodies is to develop efficient purifying technologies. One such immensely beneficial procedure that has been in use is that of purification of water using 'adsorbents'. Indigenous minerals and natural plants products have potential for removing many pollutants viz. fluoride, arsenic, nitrate, heavy metals, pesticides as well as trihalomethanes. Adsorbents which are derived from carbon, alumina, zeolite, clay minerals, iron ores, industrial by products, and natural products viz. parts of the plants, herbs and algal biomass offer promising potential of removal. In the recent years attention has been paid to develop process involving screening/pretreatment/activation/impregnation using alkalies, acids, alum, lime, manganese dioxide, ferric chloride and other chemicals which are found to enhance their adsorbing efficiency. Chemical characterization of these adsorbents recapitulates the mechanism of the process. It is imperative to observe that capacities of the adsorbents may vary depending on the characteristics, chemical modifications and concentration of the individual adsorbent. Removal kinetics is found to be based on the experimental conditions viz. pH, concentration of the adsorbate, quantity of the adsorbent and temperature. It is suggested that isotherm model is suitable tool to assess the adsorption capacities in batch and column modes. Safety evaluation and risk assessment of the process/products may be useful to provide guidelines for its sustainable disposal. PMID:20120453

  3. Effect of phosphate additives on the microstructure, bioactivity, and degradability of microarc oxidation coatings on Mg-Zn-Ca-Mn alloy.

    Dou, Jinhe; You, Qiongya; Gu, Guochao; Chen, Chuanzhong; Zhang, Xihua

    2016-01-01

    Calcium phosphate coatings were prepared on the surface of self-designed Mg-Zn-Ca-Mn alloy using microarc oxidization technology. To characterize the microstructures, cross-section morphologies, and compositions of the coatings, the authors used scanning electron microscopy equipped with an energy-disperse spectrometer, x-ray diffraction, and Fourier transform infrared spectroscopy. Potentiodynamic polarization in the simulated body fluid (SBF) was used to evaluate the corrosion behaviors of the samples. An SBF immersion test was used to evaluate the coating bioactivity and degradability. After the immersion tests, some bonelike apatite formed on the coating surfaces indicate that bioactivity of the coatings is excellent. The coating prepared in electrolyte containing (NaPO3)6 had slower degradation rate after immersion test for 21 days. PMID:27440396

  4. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

    2016-08-01

    The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  5. Elution by Le Chatelier's principle for maximum recyclability of adsorbents: applied to polyacrylamidoxime adsorbents for extraction of uranium from seawater.

    Oyola, Yatsandra; Vukovic, Sinisa; Dai, Sheng

    2016-05-28

    Amidoxime-based polymer adsorbents have attracted interest within the last decade due to their high adsorption capacities for uranium and other rare earth metals from seawater. The ocean contains an approximated 4-5 billion tons of uranium and even though amidoxime-based adsorbents have demonstrated the highest uranium adsorption capacities to date, they are still economically impractical because of their limited recyclability. Typically, the adsorbed metals are eluted with a dilute acid solution that not only damages the amidoxime groups (metal adsorption sites), but is also not strong enough to remove the strongly bound vanadium, which decreases the adsorption capacity with each cycle. We resolved this challenge by incorporating Le Chatelier's principle to recycle adsorbents indefinitely. We used a solution with a high concentration of amidoxime-like chelating agents, such as hydroxylamine, to desorb nearly a 100% of adsorbed metals, including vanadium, without damaging the metal adsorption sites and preserving the high adsorption capacity. The method takes advantage of knowing the binding mode between the amidoxime ligand and the metal and mimics it with chelating agents that then in a Le Chatelier's manner removes metals by shifting to a new chemical equilibrium. For this reason the method is applicable to any ligand-metal adsorbent and it will make an impact on other extraction technologies. PMID:27117598

  6. Experimental study on extraction chromatography using CMPO adsorbent. 2

    In order to study the applicability of extraction chromatographic method to the TRUEX and SETFICS processes for MA separation in the program of Feasibility Study on Commercialized Fast Reactor Cycle Systems, this work investigated some basic characteristics of a novel silica-supported CMPO adsorbent and synthesis method of the porous silica-support. Resistant behavior of the CMPO adsorbent against nitric acid, temperature and γ-irradiation has been examined experimentally. Removal tests of CMPO dissolved in aqueous solution were conducted. Furthermore, synthesis procedure for preparing the silica-support was investigated. Obvious decrease in adsorption capacity of the CMPO adsorbent resulted from HNO3-treatment was not observed, indicating the adsorbent has excellent resistance to HNO3. HNO3-treatment at 80 caused a decrease in adsorption capacity by 4-12% and the capacity decreased with increasing HNO3 concentration. The capacity decrease is resulted from the decomposition and dissolution of a small amount of CMPO without the structure change of the adsorbent. On the other hand, in the cases of γ-irradiation the adsorption capacity declined markedly with the increase of absorption dose and structure change of the adsorbent was also observed. The CMPO dissolved in aqueous solution with a concentration of about 40 ppm could be effectively removed by using the column packed with a porous adsorbent such as SiO2-P. As a manufacture method of the porous SiO2 support, the details of ultrasonic vibration technique for dividing molten SiO2 were surveyed. (author)

  7. Experimental study on extraction chromatography using CMPO adsorbent

    In order to study the applicability of extraction chromatographic method to the TRUEX and SETFICS processes for MA separation in the program of Feasibility Study on Commercialized Fast Reactor Cycle Systems, this work investigated some basic characteristics of a novel silica-supported CMPO adsorbent. The leaching behavior of CMPO from the adsorbent by specified eluent solutions, adsorption capacity, dissolution method of CMPO form the support and thermal decomposition performance have been examined experimentally. The experimental results indicate that the leaching of CMPO from the adsorbent is resulted from the solubility of CMPO in an eluent solution. The dissolubility by a dilute nitric acid is relatively high and the concentration of leached CMPO is about 20-50 ppm. It was found that almost the same amount of CMPO is leached out from the adsorbent packed column during the elution operation. However, the leaching problem of CMPO would be cleared by packing an extra amount of the adsorbent to column or by using the eluent solutions saturated by CMPO. The adsorption capacity of the CMPO adsorbent for Nd(III) in 3M HNO3 solution was measured as 0.19-0.22 mmol/g, which is approximately 70-80% of the maximum adsorption amount as M(NO3)3·3 CMPO. The impregnated CMPO can be completely dissolved out from the support by an organic solvent such as acetone. From the thermal analysis results, it was recognized that CMPO in the adsorbent decomposed at 200degC and the SDB-polymer at 290degC, leaving the silica particles. (author)

  8. Effect of Electrolyte Temperature on Microstructure and Corrosion Resistance of Micro - Arc Oxidation Coatings of Magnesium Alloy%AZ31B镁合金微弧氧化电解液温度对膜组织与性能的影响

    翟彦博; 陈红兵; 马秀腾

    2013-01-01

    on the bath potential for micro-arc oxidation of AZ31B Mg alloy as well as the growth rate, microhardness, corrosion resistance and microstructure of as-obtained micro-arc oxidation coatings was investigated. It was found that elevating electrolyte temperature favored to accelerated growth of the micro-arc oxidation coatings on Mg alloy but led to enlarged discharge channel and reduced compactness of the coatings, thereby resulting in reduced microhardness and corrosion resistance of the micro-arc oxidation coatings.%电解液温度是影响镁合金微孤氧化膜形成及质量的关键因素之一,过去对此鲜有系统研究.为此,对比研究了20,40,60℃3种电解液温度对AZ31B镁合金微弧氧化膜的生长速度、槽压、显微硬度、耐蚀性和微观组织的影响.结果显示,较高的电解液温度可以提高氧化膜的生长速度,但会导致膜层中的放电通道增大,使其致密性变差,从而降低了膜层的显微硬度与耐蚀性.

  9. Effect of ZrO2 particle on the performance of micro-arc oxidation coatings on Ti6Al4V

    Li, Hong; Sun, Yezi; Zhang, Jin

    2015-07-01

    This paper investigates the effect of ZrO2 particle on the oxidation resistance and wear properties of coatings on a Ti6Al4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations micron ZrO2 particles were added in phosphate electrolyte and dispersed by magnetic stirring apparatus. The composition of coating was characterized using X-ray diffraction and energy dispersive spectrum, and the morphology was examined using SEM. The high temperature oxidation resistance of the coating sample at 700 °C was investigated. Sliding wear behaviour was tested by a wear tester. The results showed that the coating consisted of ZrTiO4, ZrO2, TiO2. With ZrO2 particle addition, the ceramic coating's forming time reduced by the current dynamic curve. It was shown that the addition of ZrO2 particles (3 g/L, 6 g/L) expressed an excellent oxidation resistance at 700 °C and wear resistance.

  10. Single-Step Assembly of Multifunctional Poly(tannic acid)-Graphene Oxide Coating To Reduce Biofouling of Forward Osmosis Membranes.

    Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Saint, Christopher P; Ginic-Markovic, Milena

    2016-07-13

    Graphene oxide (GO) nanosheets have antibacterial properties that have been exploited as a biocidal agent used on desalination membrane surfaces in recent research. Nonetheless, improved strategies for efficient and stable attachment of GO nanosheets onto the membrane surface are still required for this idea to be commercially viable. To address this challenge, we adopted a novel, single-step surface modification approach using tannic acid cross-linked with polyethylene imine as a versatile platform to immobilize GO nanosheets to the surface of polyamide thin film composite forward osmosis (FO) membranes. An experimental design based on Taguchi's statistical method was applied to optimize the FO processing conditions in terms of water and reverse solute fluxes. Modified membranes were analyzed using water contact angle, adenosine triphosphate bioluminescence, total organic carbon, Fourier transform infrared spectroscopy, ζ potential, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. These results show that membranes were modified with a nanoscale (<10 nm), smooth, hydrophilic coating that, compared to pristine membranes, improved filtration and significantly mitigated biofouling by 33% due to its extraordinary, synergistic antibacterial properties (99.9%). PMID:27294568

  11. Effect of biomass addition on the surface and adsorption characterization of carbon-based adsorbents from sewage sludge

    Changzi Wu; Min Song; Baosheng Jin; Yimin Wu; Yaji Huang

    2013-01-01

    Sewage sludge with the additive corn cob was used as prescusor to prepare sludge-based carbon adsorbents by pyrolysis method.And then,the carbonizated products were activated with potassium hydroxide.The mixing ratio of the corn cob to sewage sludge was investigated.The surface area and pore size distribution,elemental composition,surface chemistry structure and the surface physical morphology were determined and compared.The results demonstrated that the addition of corn cob into the sewage sludge sample could effectively improve the surface area (from 287 to 591 m2/g) and the microporosity (from 5% to 48%) of the carbon based adsorbent,thus enhancing the adsorption behavior.The sulfur dioxide adsorption capacity was measured according to breakthrough test.It was found that the sulfur dioxide adsorption capacity of the adsorbents was obviously enhanced after the addition of the corn cob.It is presumed that not only highly porous adsorbents,but also a high metallic content of these materials are required to achieve good performances.

  12. Novel adsorbent from agricultural waste (cashew NUT shell for methylene blue dye removal: Optimization by response surface methodology

    Ramalingam Subramaniam

    2015-09-01

    Full Text Available Activated carbon, prepared from an agricultural waste, cashew nut shell (CNS was utilized as an adsorbent for the removal of methylene blue (MB dye from aqueous solution. Batch adsorption study was carried out with variables like pH, adsorbent dose, initial dye concentration and time. The response surface methodology (RSM was applied to design the experiments, model the process and optimize the variable. A 24 full factorial central composite design was successfully employed for experimental design and analysis of the results. The parameters pH, adsorbent dose, initial dye concentration, and time considered for this investigation play an important role in the adsorption studies of methylene blue dye removal. The experimental values were in good agreement with the model predicted values. The optimum values of pH, adsorbent dose, initial dye concentration and time are found to be 10, 2.1846 g/L, 50 mg/L and 63 min for complete removal of MB dye respectively.

  13. Structural characteristics and oil-removal mechanisms of the adsorbents made from petrochemical sludge

    LIU Jian-bin; SANG Yi-ming; TAN Wen-jie; HE Xu-wen; LI Fa-sheng

    2004-01-01

    A new type of carbon-inorganic absorbent with good oil-removing performance is prepared by sintering and activating petrochemical sludge. Of the absorbents prepared by three different methods (non-activated, vapor /840 ℃/6 h, CO2/1 000 ℃/2 h), the one prepared by the second method is the best in oil-removing, which can remove 60% of oil from petrochemical wastewater with a concentration of 76.42 mg/L. X-ray Diffraction (XRD) analysis shows that the constituents of the adsorbents are basically similar to those of inorganic granulating materials, such as SiO2, Al2O3, orthoclase feldspar, iron ore, etc. Composition analysis reveals that the activated absorbent has a large specific surface area with a high carbon content in activated compositions and a good oil-removing capability.

  14. Adsorption behavior of lithium from seawater using manganese oxide adsorbent

    The deuterium-tritium (D-T) fusion reactor system is expected to provide the main source of electricity in the future. Large amounts of lithium will be required, dependent on the reactor design concept, and alternative resources should be found to provide lithium inventories for nuclear fusion plants. Seawater has recently become an attractive source of this element and the separation and recovery of lithium from seawater by co-precipitation, solvent extraction and adsorption have been investigated. Amongst these techniques, the adsorption method is suitable for recovery of lithium from seawater, because certain inorganic ion-exchange materials, especially spinel-type manganese oxides, show extremely high selectivity for the lithium ion. In this study, we prepared a lithium adsorbent (HMn2O4) by elution of spinel-type lithium di-manganese-tetra-oxide (LiMn2O4) and examined the kinetics of the adsorbent for lithium ions in seawater using a pseudo-second-order kinetic model. The intermediate, LiMn2O4, can be synthesized from LiOH·H2O and Mn3O4, from which the lithium adsorbent can subsequently be prepared via acid treatment., The adsorption kinetics become faster and the amount of lithium adsorbed on the adsorbent increases with increasing solution temperature. The thermodynamic values, ΔG0, ΔH0 and ΔS0, indicate that adsorption is an endothermic and spontaneous process. (author)

  15. [DSC and FTIR study of adsorbed lysozyme on hydrophobic surface].

    Lei, Zu-meng; Geng, Xin-peng; Dai, Li; Geng, Xin-du

    2008-09-01

    During a process of hen egg white lysozyme adsorption and folding on a moderately hydrophobic surface (PEG-600), the effects of salt((NH4)2SO4) concentrations, surface coverage and denaturant (guanidine hydrochloride, GuHCl) concentrations on thermal stability and the changes in the molecular conformation of adsorbed native and denatured lysozyme without aqueous solution were studied with a combination of differential scanning calorimetry (DSC) with FTIR spectroscopy. The results showed that temperature due to endothermic peaks was reduced and the disturbance increased at higher temperature with the increase in salt concentration and surface coverage of adsorbed protein. beta-Sheet and beta-Turn stucture increased while alpha-Helix structure decreased after the adsorption. The peaks corresponding to both C-C stretching frequency in 1400-1425 cm(-1) and amide I band frequency in 1650-1670 cm(-1) of adsorbed denatured lysozyme can be detected in FTIR spectra while that due to amide I band frequency of adsorbed native lysozyme almost can't be observed. Adsorption resulted in structural loss of adsorbed native lysozyme, whose performance was less stable. PMID:19093560

  16. Adsorption of rare earths with crown ether adsorbents

    Crown ether - phosphotungstic acid (PW) and crown ether -phosphomolybdic acid (PMo) precipitates, and also the granular entrapped crown ether - PMo (or PW) in polyacrylamide, were prepared and applied as adsorbents for rare earth metal ions. Adsorbents containing 15-crown-5, such as 15-crown-5 - PMo, were better adsorbents than the other crown ether precipitates. The adsorption capacity of 15-crown-5 - PMo for Eu3+ was determined and corresponded to about 0.166 mmol of Eu3+ per gram of the absorbent. The effects of pH and metal ion concentration on adsorption were also investigated. Crown ether - PMo (or PW) precipitates underwent hydrolysis at pH >= 1, but the granular entrapped crown ether - PMo (or PW) - polyacrylamide adsorbents were not hydrolysed at pH >= 1. The adsorption of individual rare earth ions with 15-crown-5 - PMo - polyacrylamide showed that Tb3+, Nd3+, Eu3+ and Gd3+ were readily adsorbed, but adsorption was difficult for Ce4+, Sm3+ and Dy3+. (author)

  17. Magnetic niobia as adsorbent of organic contaminants in aqueous medium: effect of temperature and pH

    This work describes novel materials based on pure iron oxide and iron oxide/niobia composite to produce a magnetic adsorbent. These materials were prepared with synthetic iron oxide and characterized by powder XRD, SEM, FTIR, TPR and Moessbauer spectroscopy. Results showed that the main iron oxides formed were goethite (α FeOOH) and maghemite (γFe2O3) with small particle size. The iron oxide and iron oxide/niobia composite showed high adsorption ability for organic compounds. The positive enthalpy indicated an endothermic adsorption process suggesting physical adsorption. (author)

  18. Studies on The Adsorption Capacity for Bilirubin of The Adsorbent Chitosan-β-Cyclodextrin

    2001-01-01

    The adsorbent crosslinked chitosan-β-cyclodextrin (β-CD) was prepared by the reaction of glutaraldehyde with chitosan and β-cyclodextrin. This type of adsorbent has high adsorption capacity for unconjugated bilirubin. The adsorption capacity was related to the β-CD content of the adsorbent; phosphate buffer concentration; temperature; pH value; ionic strength and the adsorbent beads. The results indicated that the chitosan-β-CD was a good adsorbent for unconjugated bilirubin with high capacity.

  19. Lithium cobalt oxide coated lithium zinc titanate anode material with an enhanced high rate capability and long lifespan for lithium-ion batteries

    Highlights: • Synthesis of LiCoO2 coated Li2ZnTi3O8 via a wet chemical process followed by heat treatment. • The high rate capability and cyclic stability are improved due to the LiCoO2 surface coating. • Electrochemical properties were tested in a charge/discharge voltage range of 0.05-3.0 V (vs. Li/Li+). - Abstract: LiCoO2 coated Li2ZnTi3O8 is synthesized by a preliminary formation of Li2ZnTi3O8 by facile solid state reaction and a following coating process with LiCoO2 nano layer via a wet chemical process followed by heat treatment. The structure and electrochemical property of the as-prepared samples have been characterized comprehensively. A thin LiCoO2 layer with a thickness of about 2 nm is uniformly coated on the surface of active particles, which does not affect the crystal structure and space group. After LiCoO2 surface modification, high discharge capacities of 192.1, 163.7, 108.2 mAh g−1 with capacity retention of 99.1, 92.3, 71.4% are obtained at 1.0, 2.0, 3.0 A g−1 after 100 cycles for the coated composite, respectively, which are obviously larger than those of un-coated sample. Besides, the discharge capacity and cyclic stability of Li2ZnTi3O8 after 1000 cycles have been enhanced after coating. Cyclic voltammograms and electrochemical impedance spectroscopy measurements prove that the LiCoO2 coating can dramatically decrease polarization and reduce the charge transfer resistance during repeated Li+ intercalation/de-intercalation process. The improved electrochemical properties of LiCoO2 coated Li2ZnTi3O8 are attributed to small particle sizes, large packed holes, high surface area and better electronic conductive

  20. The effect of the addition of colloidal iridium oxide into sol-gel obtained titanium and ruthenium oxide coatings on titanium on their electrochemical properties.

    Panić, Vladimir V; Dekanski, Aleksandar B; Mitrić, Miodrag; Milonjić, Slobodan K; Misković-Stanković, Vesna B; Nikolić, Branislav Z

    2010-07-21

    Electrochemical properties of sol-gel processed Ti(0.6)Ir(0.4)O(2) and Ti(0.6)Ru(0.3)Ir(0.1)O(2) coatings on titanium substrate were investigated using cyclic voltammetry, polarization measurements and electrochemical impedance spectroscopy and compared to the properties of Ti(0.6)Ru(0.4)O(2) coating. The role of iridium oxide in the improvement of the electrocatalytic, capacitive and stability properties of titanium anodes activated by a RuO(2)-TiO(2) coating is discussed. The oxide sols were prepared by forced hydrolysis of the metal chlorides. The characterization by dynamic light scattering and X-ray diffraction showed that polydisperse oxide sols were obtained with the particles tending to form agglomerates. The presence of IrO(2) causes a suppression of the X-ray diffraction peaks of TiO(2) and RuO(2) in the sol-gel prepared Ti(0.6)Ir(0.4)O(2) and Ti(0.6)Ru(0.3)Ir(0.1)O(2) coatings. The IrO(2)-containing coatings had an enhanced charge storage ability and activity for the oxygen evolution reaction (OER) in comparison to Ti(0.6)Ru(0.4)O(2) coating. The voltammogram of the Ti(0.6)Ir(0.4)O(2)/Ti electrode showed well-resolved peaks related to Ir redox transitions, which are responsible for the enhanced charge storage ability of IrO(2)-containing coatings. Redox transitions of Ir were also registered in the high-frequency domain of the ac impedance spectra of the coatings as a semicircle with characteristics insensitive to the electrolyte composition and to the electrode potential prior to OER. However, the semicircle characteristics were different for the two IrO(2)-containing coatings, as well as at potentials outside the OER in comparison to those at which the OER occurs. PMID:20544088

  1. Emanation-thermal analysis of basalt fiber adsorbents

    Complex emanation-thermal analysis is used for investigating structural changes in basalt adsorbents taking place during thermal affects on material. Adsorbent is prepared by two-stage treatment of staple basalt fibers by hydrochloric acid. Isotherms of sorption of liquid nitrogen vapors by new sorbents are measured. Areas of the open surface, porosity and pores size spectra of leached fibers are calculated. It is determined by the method of thermostimulated gassing that adsorbed water is in two energetically different states in porous basalt fiber: basic part of water vapors is desorbed at 90-110 Deg C, remained part -at 300-320 Deg C. Full regeneration of sorbent requires warming up to 550 Deg C

  2. Synthesis of silica adsorbent and its selective separation for flavone

    Yuqing ZHANG; Yahui ZHANG; Zhen QIN; Zhenrong MA

    2008-01-01

    One kind of built,in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting technology by the following steps:synthesis of precursor from the reaction between water soluble rutin (as template molecule) and the functional monomer chloropropyltriethoxysilane, co,hydrolysis of the precursor and tetraethoxysilane (TEOS), sol,gel aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high adsorption capacity for rutin, and good adsorptionselectivity towards rutin even under the interference of a flavone with a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR spectra indicate that new bond was generated during the recognition process.

  3. Decontamination of radioactive process waste water by adsorbing colloid flotation

    Adsorbing colloid flotation was tested to remove 144Ce, 60Co, 65Zn, and 89Sr from radioactive process waste water. Potassium oleate was used as the collector, and Fe(III) hydroxide, Al(III) hydroxide or Co(II) hydroxide as the coprecipitant. Under optimal conditions, removals exceeding 99% could be achieved for 65Zn with any of the tested coprecipitants, for 144Ce with Fe(III) and Co(II) hydroxides and for 60Co with only Co(II) hydroxide. For 89Sr removals of 90% could be achieved only with Fe(III) hydroxide. The adsorbing colloid flotation process was compared with both chemical precipitation and ion exchange. Advantages of adsorbing colloid flotation are discussed. (author)

  4. A Review of Adsorbents Used for Storm Water Runoff Cleaning

    Andrius Agintas

    2011-04-01

    Full Text Available Heavy metals, petroleum products, sediments and other pollutants get in the environment with insufficiently cleaned storm water runoff. Contaminated storm water runoff is one of the most significant sources for pollution in rivers, lakes and estuaries. Storm water runoff must be treated using not only simple methods but also using adsorption processes. Adsorbents can be natural organic, natural nonorganic and synthetic. Main adsorption characteristic, way of utilization and storm water runoff inflow rate, quantity and pollution need to be investigated when trying to use adsorbents in reasonably way. It is very important to treat storm water properly during the primary mechanical treatment otherwise adsorbents will act as mechanical filters.Article in Lithuanian

  5. Extracting uranium from seawater: Promising AF series adsorbents

    Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater

  6. SAPO-34 coated adsorbent heat exchanger for adsorption chillers

    In this work, adsorbent coatings on aluminum surfaces were prepared by dip-coating method starting from a water suspension of SAPO-34 zeolite and a silane-based binder. Silane-zeolite coatings morphology and surface coverage grade were evaluated by scanning electron microscopy. Adhesive and mechanical properties were evaluated by peel, pull-off, impact and micro-hardness tests, confirming the good interaction between metal substrate, binder and zeolite. Adsorption equilibrium and kinetics of water vapour adsorption on the adsorbent coating were studied in the range T = 30–150 °C and pH2O = 11 mbar using a CAHN 2000 thermo-balance. It was found that, in the investigated conditions, the organic binder doesn't affect the water adsorption capacity and adsorption kinetics of the original SAPO-34 zeolite. Subsequently, the zeolite coating was applied on a finned flat-tubes aluminum heat exchanger realizing a full-scale AdHEx with an uniform adsorbent coating 0.1 mm thick and a metal/adsorbent mass ratio = 6. The cooling capacity of the realized coated AdHEx was measured by a lab-scale adsorption chiller under realistic operating conditions for air conditioning applications. The coated AdHEx produced up to 675 W/kgads specific cooling power with a cycle time of 5 min. Adsorption stability of the coated adsorber subjected to 600 sorption cycles was successfully verified. - Highlights: • Adsorbent coatings on aluminum surfaces were prepared by dip-coating method. • Silane-zeolite coatings morphology, and mechanical properties were studied. • The zeolite coating was applied on a finned flat-tubes aluminum heat exchanger. • The coated AdHEx was tested in a lab scale adsorption chiller

  7. Electrochemical Studies of Paraquat Adsorbed onto Crystalline Apatite

    Moulay Abderrahim EL MHAMMEDI

    2007-09-01

    Full Text Available The carbon paste electrode (CPE has been used to analyze the electrochemical behavior of paraquat (PQ adsorbed onto synthesized hydroxyapatite phosphocalcique (HAP in K2SO4 (0.1M. The cyclic voltammetry results obtained corrobate with square wave voltammetry. The influence of variables such as the concentration of paraquat adsorbed onto apatite (PQ/HAP, and the potential scan rate was tested.X-ray diffraction analysis (XRD, Fourier transformed infrared spectroscopy (FTIR analysis and inductively coupled plasma-atomic emission spectrometry (ICP, AES were used for characterization of the apatite.

  8. Removal of uranium by the adsorbents produced from coffee residues

    Large amounts of coffee residues contaminate the environment and reprocessing of them as valuable products such as adsorbents will be a good solution from an environmental and economic point of view. In this study some adsorbents were produced from coffee residues and used for batch removal experiments of uranium from aqueous solutions. The adsorption kinetics was found to follow the Lagergren equation. The adsorption process was described with the Langmuir and Freundlich isotherms. Additionally, the effect of different cations on the adsorption of uranium was studied. (author)

  9. Hydrogen molecule on lithium adsorbed graphene: A DFT study

    Kaur, Gagandeep; Gupta, Shuchi; Gaganpreet, Dharamvir, Keya

    2016-05-01

    Electronic structure calculations for the adsorption of molecular hydrogen on lithium (Li) decorated and pristine graphene have been studied systematically using SIESTA code [1] within the framework of the first-principle DFT under the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA)[2], including spin polarization. The energy of adsorption of hydrogen molecule on graphene is always enhanced by the presence of co-adsorbed lithium. The most efficient adsorption configuration is when H2 is lying parallel to lithium adsorbed graphene which is in contrast to its adsorption on pristine graphene (PG) where it prefers perpendicular orientation.

  10. Photoinduced Surface Dynamics of CO Adsorbed on a Platinum Electrode

    Noguchi, Hidenori; Okada, Tsubasa; Uosaki, Kohei

    2006-01-01

    The surface dynamics of adsorbed CO molecules formed by dissociative adsorption of HCHO at a polycrystalline Pt electrode/electrolyte solution interface was studied by picosecond time-resolved sum-frequency generation (TR-SFG) spectroscopy. A SFG peak at 2050-2060 cm^[-1] was observed at the Pt electrode in HClO4 solution containing HCHO at 0-300 mV (vs Ag/AgCl), indicating the formation of adsorbed CO at an atop site of the Pt surface as a result of dissociative adsorption of HCHO. The peak ...

  11. Removal of fluoride from groundwater by adsorption onto La(III)- Al(III) loaded scoria adsorbent

    The La3+-Al3+ loaded scoria (La-Al-Scoria) was prepared as adsorbent for the fluoride removal from groundwater. The connecting time experiment indicated that the fluoride adsorption process reached equilibrium within 5 hours. The kinetics of fluoride ion adsorption onto La-Al-Scoria was followed the pseudo-second order with correlation coefficient value (R2) of 0.997. The isotherm data was well fitted to both of the Freundlich and Langmuir isotherm models, the R2 of Freundlich and Langmuir were 0.98 and 0.97, respectively. Subsequently, the adsorbent was characterized by scanning electron microscope (SEM), Energy dispersive analysis of X-ray (EDX), X-ray diffraction analysis (XRD) and X-ray Photoelectron Spectroscopy (XPS) measurements. SEM visual expressed that the dense canal surface structure of natural scoria appeared a large amount of rod-like composite after modification. The XRD and XPS instrumental studies revealed that the La3+ and Al3+ were loaded on the surface of modified scoria and the fluoride ion was adsorbed on the La-Al-Scoria. The large amount of La-Al-O composite oxide existed onto the surface of La-Al-Scoria was the immanent cause for the excellent adsorption capacity of fluoride ion.

  12. Cauliflower-like CuI nanostructures: Green synthesis and applications as catalyst and adsorbent

    Highlights: → In this study we report a green, environment-friendly, efficient, and direct one-step process for the preparation of CuI cauliflower. → The as-formed CuI cauliflower shows excellent catalytic activity for coupling reaction between benzylamine and iodobenzene. → The cauliflower-like CuI nanostructures have been successfully demonstrated as adsorbent for Cd (II) with high removal capacity. → To the best of our knowledge, it is the first report that nanostructured CuI acts as catalyst for coupling reaction and adsorbent for heavy metal ion. → It is also a good example for the organic combination of green chemistry and functional materials. - Abstract: Cauliflower-like CuI nanostructures is realized by an ampicillin-assisted clean, nontoxic, environmentally friendly synthesis strategy at room temperature. The morphology, composition, and phase structure of as-prepared powders were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results show that ampicillin plays dual roles, reducing and morphology-directing agents, in the formation of the products. A possible growth mechanism of the cauliflower-like CuI nanostructures is tentatively proposed. The preliminary investigations show that the cauliflower-like CuI structure not only exhibits high catalytic activity with respect to coupling reaction between benzylamine and iodobenzene but also possesses high removal capacity for Cd (II), which may be ascribed to the high specific surface area of the special configuration. To the best of our knowledge, it is the first report that cauliflower-like CuI nanoparticles act as catalyst for coupling reaction and adsorbent for heavy metal ion.

  13. Cauliflower-like CuI nanostructures: Green synthesis and applications as catalyst and adsorbent

    Jiang Yi [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Gao Shuyan, E-mail: shuyangao@htu.cn [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Li Zhengdao; Jia Xiaoxia; Chen Yanli [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China)

    2011-08-15

    Highlights: > In this study we report a green, environment-friendly, efficient, and direct one-step process for the preparation of CuI cauliflower. > The as-formed CuI cauliflower shows excellent catalytic activity for coupling reaction between benzylamine and iodobenzene. > The cauliflower-like CuI nanostructures have been successfully demonstrated as adsorbent for Cd (II) with high removal capacity. > To the best of our knowledge, it is the first report that nanostructured CuI acts as catalyst for coupling reaction and adsorbent for heavy metal ion. > It is also a good example for the organic combination of green chemistry and functional materials. - Abstract: Cauliflower-like CuI nanostructures is realized by an ampicillin-assisted clean, nontoxic, environmentally friendly synthesis strategy at room temperature. The morphology, composition, and phase structure of as-prepared powders were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results show that ampicillin plays dual roles, reducing and morphology-directing agents, in the formation of the products. A possible growth mechanism of the cauliflower-like CuI nanostructures is tentatively proposed. The preliminary investigations show that the cauliflower-like CuI structure not only exhibits high catalytic activity with respect to coupling reaction between benzylamine and iodobenzene but also possesses high removal capacity for Cd (II), which may be ascribed to the high specific surface area of the special configuration. To the best of our knowledge, it is the first report that cauliflower-like CuI nanoparticles act as catalyst for coupling reaction and adsorbent for heavy metal ion.

  14. Polarity of an MCM-41 adsorbent surface modified with methyl and phenyl groups based on data from gas chromatography

    Sukhareva, D. A.; Gus'kov, V. Yu.; Karpov, S. I.; Kudasheva, F. Kh.; Roessner, F.; Borodina, E. V.

    2016-02-01

    The polarity of an MCM-41 adsorbent surface and organosilylated composites based on it with grafted trimethylsilane and dimethylphenylsilane groups is studied via inverse gas chromatography at infinite dilution. The dispersion and specific components of the value proportional to the Helmholtz adsorption energy are calculated, and a comparative analysis of the surface polarity of MCM-41 and its modified analogs relative to the commercially available C-120 silica gel is performed. The electrostatic and donor-acceptor components of the specific Helmholtz adsorption energy are calculated through linear decomposition of the adsorption energy. It is established that MCM-41 is less polar than C-120. The modification of the initial adsorbent surface leads to a reduction in polarity, due mainly to the weakening of induction and orientation interactions. It is concluded that the surfaces of the modified samples retain the ability to form hydrogen bonds.

  15. Photochemistry of adsorbed nitrate on aluminum oxide particle surfaces.

    Rubasinghege, Gayan; Grassian, Vicki H

    2009-07-01

    Nitrogen oxides, including nitrogen dioxide and nitric acid, react with mineral dust particles in the atmosphere to yield adsorbed nitrate. Although nitrate ion is a well-known chromophore in natural waters, little is known about the surface photochemistry of nitrate adsorbed on mineral particles. In this study, nitrate adsorbed on aluminum oxide, a model system for mineral dust aerosol, is irradiated with broadband light (lambda > 300 nm) as a function of relative humidity (RH) in the presence of molecular oxygen. Upon irradiation, the nitrate ion readily undergoes photolysis to yield nitrogen-containing gas-phase products including NO(2), NO, and N(2)O, with NO being the major product. The relative ratio and product yields of these gas-phase products change with RH, with N(2)O production being highest at the higher relative humidities. Furthermore, an efficient dark reaction readily converts the major NO product into NO(2) during post-irradiation. Photochemical processes on mineral dust aerosol surfaces have the potential to impact the chemical balance of the atmosphere, yet little is known about these processes. In this study, the impact that adsorbed nitrate photochemistry may have on the renoxification of the atmosphere is discussed. PMID:19534452

  16. Utilization of Roselle charcoal as nitrate-nitrogen adsorbent

    Yimrattanabovorn, J.

    2006-11-01

    Full Text Available Recently, the attempts have been made by utilizing natural material as an adsorbent for wastewater treatment due to its low cost, low energy requirement and the fewer chemicals used. In this study, Roselle (Hibiscus sabdariffa L. var. altissima was prepared to use as a charcoal adsorbent in the treatment process. The nitrate-nitrogen adsorption capacities of Roselle charcoal with 2 different particle sizes, A (4.75- .30 mm and B (2.00-4.75 mm were measured and compared with an activated carbon (AC. The equilibrium data fitted well with the Freundlich Isotherm. The K values related to the capacity of adsorbent for nitratenitrogen of such charcoal studied were in the following orders: AC > B > A expressed as 0.0321, 0.0147 and 0.0071 respectively. In addition, activated carbon required less contact time to reach equilibrium than both of Roselle charcoal A and B. Although removal efficiency of activated carbon was higher than that of Roselle charcoal, Roselle charcoal is an interesting alternative adsorbent due to the lower cost of its production.

  17. Interactions of organic contaminants with mineral-adsorbed surfactants

    Zhu, L.; Chen, B.; Tao, S.; Chiou, C.T.

    2003-01-01

    Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insight to interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

  18. Interactions between adsorbed macromolecules : measurements on emulsions and liquid films

    Vliet, van T.

    1977-01-01

    The aim of this study was to gain more insight into the factors, determining the inter- and intramolecular interactions between adsorbed macromolecules. To that end several experimental and theoretical approaches were followed, using well-defined systems. It was shown that these interactions could c

  19. Pulling adsorbed self-avoiding walks from a surface

    Guttmann, Anthony J.; Jensen, I.; Whittington, S. G.

    2014-01-01

    We consider a self-avoiding walk model of polymer adsorption where the adsorbed polymer can be desorbed by the application of a force, concentrating on the case of the square lattice. Using series analysis methods we investigate the behaviour of the free energy of the system when there is an attractive potential ɛ with the surface and a force f applied at the last vertex, normal to the surface, and extract the phase boundary between the ballistic and adsorbed phases. We believe this to be exact to graphical accuracy. We give precise estimates of the location of the transition from the free phase to the ballistic phase, which we find to be at yc = exp (f/kBTc) = 1, and from the free phase to the adsorbed phase, which we estimate to be at ac = exp ( - ɛ/kBTc) = 1.775 615 ± 0.000 005. In addition we prove that the phase transition from the ballistic to the adsorbed phase is first order.

  20. Pulling adsorbed self-avoiding walks from a surface

    We consider a self-avoiding walk model of polymer adsorption where the adsorbed polymer can be desorbed by the application of a force, concentrating on the case of the square lattice. Using series analysis methods we investigate the behaviour of the free energy of the system when there is an attractive potential ϵ with the surface and a force f applied at the last vertex, normal to the surface, and extract the phase boundary between the ballistic and adsorbed phases. We believe this to be exact to graphical accuracy. We give precise estimates of the location of the transition from the free phase to the ballistic phase, which we find to be at yc = exp (f/kBTc) = 1, and from the free phase to the adsorbed phase, which we estimate to be at ac = exp ( − ϵ/kBTc) = 1.775 615 ± 0.000 005. In addition we prove that the phase transition from the ballistic to the adsorbed phase is first order. (paper)

  1. Adsorption of iodine by silver-impregnated hydrophobic adsorbent

    Hydrophobic adsorbents, which consist of porous styrene-divinylbenzene copolymer (SDB) impregnated with silver, were developed for the removal of iodine from the dissolver off-gas (DOG). The adsorption of iodine in a simulated off-gas including iodine, NOx and water vapor was examined by use of an adsorption column packed with the hydrophobic adsorbents. Silver impregnation methods using organic solutions were proposed. By use of dioxan and butylamine, which can swell the SDB easily, silver nitrate and metallic silver were uniformly distributed in the SDB particles. The breakthrough of iodine was not influenced by the presence of NOx and water vapor. For a macroporous SDB with the pore volume of 1.59 ml/g-SDB and the average pore diameter of 500A, impregnated with metallic silver at silver content of 28 wt%, a high adsorption capacity of 0.14g-I2/cm3-adsorbent was obtained, compared to that of a commercial adsorbent. AgNO3-impregnated silica gel. The impregnated silver was utilized about 91% for the iodine adsorption. (author)

  2. Alpha spectrometry sample preparation using selectively adsorbing thin films

    Several years ago, Switzerland introduced limits for natural radionuclides in food, e.g. 1 Bq/l for 226Ra or 10 Bq/l for the sum of 238U and 234U in drinking water. To make enforcement by regional (cantonal) laboratories more attractive, simplified analytical methods had to be offered, at least for drinking water. A first step has been the development of radium adsorbing sheets. A 20 mm x 20 mm MnO2 film on a polyamide substrate adsorbs more than 80% of the radium present in a 100 ml water sample within 6 h. The film is thin enough to allow for high resolution alpha spectrometry. A second step now under way is to produce thin films, which selectively adsorb uranium. Actually, an ion exchange resin with diphosphonic and sulfonic acid groups is used for this purpose. Although not yet very thin, these films make possible energy resolutions far better than with any liquid scintillation alpha spectrometry method. Adsorption efficiencies are more than 80% after 20 h exposition to a 100 ml water sample (20 mm x 20 mm sheet). A third step is to have a system that measures radionuclide concentrations in water on-line. A prototype is presented where radionuclides are adsorbed on a film in contact with the water. A Si-detector placed on the other side of the film support counts the alphas passing through

  3. Chitosan membrane adsorber for low concentration copper ion removal.

    Wang, Xiaomin; Li, Yanxiang; Li, Haigang; Yang, Chuanfang

    2016-08-01

    Thin chitosan membranes with symmetric and interconnected pore structure were prepared using silica as porogen, and their physical properties including pore structure, pore size distribution, porosity and water affinity were analyzed. The membrane showed a maximum Cu(II) adsorption capacity of 87.5mg/g in static adsorption, and the adsorption fitted pseudo-second order kinetics and Toth adsorption isotherm. The membranes were then stacked in layers as an adsorber to remove small concentration Cu(II) from water dynamically. At feed concentration of 5mg/L, the adsorber could retain Cu(II) effectively when its thickness reached over 200μm, and the performance was further improved by using more membranes layers. Within a certain limit, the adsorber showed a 'flow-independent' loading behavior, an indication of fast mass transfer inside the membrane. The adsorption process was correlated well with bed depth service time (BDST) model, Thomas model and Yoon and Nelson model, and the adsorber was also found to be regenerable and re-usable. PMID:27112875

  4. Extracting uranium from seawater: Promising AI series adsorbents

    A series of adsorbent (AI10 through AI17) were successfully developed at ORNL by radiation induced graft polymerization (RIGP) of acrylonitrile (AN) and vinylphosphonic acid (VPA) (at different mole/mole ratios) onto high surface area polyethylene fiber, with higher degree of grafting which ranges from 110 300%. The grafted nitrile groups were converted to amidoxime groups by reaction with 10 wt% hydroxylamine at 80 C for 72 hours. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 171-187 g-U/kg-ads irrespective of %DOG. The performance of the adsorbents for uranium adsorption in natural seawater was also carried out using flow-through-column at Pacific Northwest National Laboratory (PNNL). The three hours KOH conditioning was better for higher uranium uptake than one hour. The adsorbent AI11 containing AN and VPA at the mole ration of 3.52, emerged as the potential candidate for higher uranium adsorption (3.35 g-U/Kg-ads.) after 56 days of exposure in the seawater in the flow-through-column. The rate vanadium adsorption over uranium was linearly increased throughout the 56 days exposure. The total vanadium uptake was ~5 times over uranium after 56 days

  5. Agricultural By-products as Mercury Adsorbents in Gas Applications

    Increased emphasis on reduction of mercury emissions from coal fired electric power plans have resulted in environmental regulations that may in the future require application of activated carbons as mercury sorbents. The sorbents could be injected into the flue gas stream where is adsorbs the merc...

  6. HYDROGEN BONDING IN POLYMERIC ADSORBENTS BASED ADSORPTION AND SEPARATION

    XUMancai; SHIZuoqing; 等

    2000-01-01

    After a concise introduction of hydrogen bonding effects in solute-solute and solute-solvent bonding,the design of polymeric adsorbents based on hydrogen bonding ,selectivity in adsorption through hydrogen bonding,and characterization of hydrogen bonding in adsorption and separation were reviewed with 28 references.

  7. PREPARATION AND ADSORBABILITY OF DEXTRAN MICROSPHERES WITH UNIFORM DIAMETER

    Ri-sheng Yao; Wen-xia Gao; Jing Sun; Ya-hua You

    2005-01-01

    The method of preparing uniform dextran microspheres with a narrow diameter distribution was introduced and the adsorbability of these microspheres was evaluated. The microspheres were prepared in W/O microemulsion using 0.5% dextran solution as the aqueous phase and n-hexane as the oil phase. Characteristics of the prepared dextran microspheres were examined with laser light blocking technique, optical microscope and ultraviolet spectrometer. The results show that the prepared dextran microspheres have uniform morphology and narrow diameter distribution, nearly 92% of them having a diameter of 56.6 μm. In vitro evaluation of adsorbability, wet dextran microspheres have good adsorption of 98.32 mg/g of model drug methylene blue in 20.86 mg/L methylene blue solution at 25℃. The adsorption of dried dextran microspheres under the same condition is 132.15 mg/g, which is even higher. And the adsorbability of dextran microspheres has significant relationship with the concentration of methylene blue and temperature. The adsorbability is better at lower temperature and higher concentration of methylene blue.

  8. Results of testing various natural gas desulfurization adsorbents

    Israelson, Gordon

    2004-06-01

    This article presents the results of testing many commercially available and some experimental sulfur adsorbents. The desired result of our testing was to find an effective method to reduce the quantity of sulfur in natural gas to less than 100 ppb volume (0.1 ppm volume). An amount of 100 ppb sulfur is the maximum limit permitted for Siemens Westinghouse solid oxide fuel cells (SOFCs). The tested adsorbents include some that rely only on physical adsorption such as activated carbon, some that rely on chemisorption such as heated zinc oxide, and some that may use both processes. The testing was performed on an engineering scale with beds larger than those used for typical laboratory tests. All tests were done at about 3.45 barg (50 psig). The natural gas used for testing was from the local pipeline in Pittsburgh and averaged 6 ppm volume total sulfur. The primary sulfur species were dimethyl sulfide (DMS), isopropyl mercaptan, tertiary butyl mercaptan, and tetrahydrothiophene. Some tests required several months to achieve a sulfur breakthrough of the bed. It was found that DMS always came through a desulfurizer bed first, independent of adsorption process. Since the breakthrough of DMS always exceeds the 100 ppb SOFC sulfur limit before other sulfurs were detected, an index was created to rate the adsorbents in units of ppm DMS × absorbent bed volume. This index is useful for calculating the expected adsorbent bed lifetime before sulfur breakthrough when the inlet natural gas DMS content is known. The adsorbents that are included in these reports were obtained from suppliers in the United States, the Netherlands, Japan, and England. Three activated carbons from different suppliers were found to have identical performance in removing DMS. One of these activated carbons was operated at four different space velocities and again showed the same performance. When using activated carbon as the basis of comparison for other adsorbents, three high-performance adsorbents

  9. Natural material adsorbed onto a polymer to enhance immune function

    Reinaque AP

    2012-08-01

    Full Text Available Ana Paula Barcelos Reinaque,1 Eduardo Luzía França,2 Edson Fredulin Scherer,3 Mayra Aparecida Côrtes,1 Francisco José Dutra Souto,4 Adenilda Cristina Honorio-França51Post Graduate Program in Material Science, 2Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, 3Post Graduate Program in Material Science, Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, 4Faculty of Medical Sciences, Federal University of Mato Grosso, Cuiabá, 5Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, MT, BrazilBackground: In this study, we produced poly(ethylene glycol (PEG microspheres of different sizes and adsorbing a medicinal plant mixture, and verified their effect in vitro on the viability, superoxide production, and bactericidal activity of phagocytes in the blood.Methods: The medicinal plant mixture was adsorbed onto PEG microspheres and its effects were evaluated by flow cytometry and fluorescence microscopy.Results: Adsorption of the herbal mixture onto the PEG microspheres was achieved and the particles were internalized by phagocytes. PEG microspheres bearing the adsorbed herbal mixture stimulated superoxide release, and activated scavenging and microbicidal activity in phagocytes. No differences in functional activity were observed when the phagocytes were not incubated with PEG microspheres bearing the adsorbed herbal mixture.Conclusion: This system may be useful for the delivery of a variety of medicinal plants and can confer additional protection against infection. The data reported here suggest that a polymer adsorbed with a natural product is a treatment alternative for enhancing immune function.Keywords: natural product, polymer, adsorption, immune function, phagocytes

  10. Effect of adsorbent addition on floc formation and clarification.

    Younker, Jessica M; Walsh, Margaret E

    2016-07-01

    Adding adsorbent into the coagulation process is an emerging treatment solution for targeting hard-to-remove dissolved organic compounds from both drinking water and industrial wastewater. The impact of adding powdered activated carbon (PAC) or organoclay (OC) adsorbents with ferric chloride (FeCl3) coagulant was investigated in terms of potential changes to the coagulated flocs formed with respect to size, structure, and breakage and regrowth properties. The ability of dissolved air flotation (DAF) and sedimentation (SED) clarification processes to remove hybrid adsorbent-coagulant flocs was also evaluated through clarified water quality analysis of samples collected in bench-scale jar test experiments. The jar tests were conducted using both a synthetic fresh water and oily wastewater test water spiked with dissolved aromatic compounds phenol and naphthalene. Results of the study demonstrated that addition of adsorbent reduced the median coagulated floc size by up to 50% but did not affect floc strength or regrowth potential after application of high shear. Experimental results in fresh water demonstrated that sedimentation was more effective than DAF for clarification of both FeCl3-PAC and FeCl3-OC floc aggregates. However, experimental tests performed on the synthetic oily wastewater showed that coagulant-adsorbent floc aggregates were effectively removed with both DAF and sedimentation treatment, with lower residual turbidity achieved in clarified water samples than with coagulation treatment alone. Addition of OC or PAC into the coagulation process resulted in removals of over half, or nearly all of the dissolved aromatics, respectively. PMID:27064206

  11. Alkali-induced nanopatterning of Ag(110) surface mediated by molecular adsorbate

    Mercurio, Giuseppe; Willenbockel, Martin; Weiss, Christian; Temirov, Ruslan; Subach, Sergey; Tautz, Stefan [Peter Gruenberg Institut (PGI-3), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technology (Germany); Bauer, Oliver; Fiedler, Benjamin; Sokolowski, Moritz [Institute for Physical and Theoretical Chemistry, University of Bonn (Germany)

    2011-07-01

    It is known for decades that alkali metals initiate the restructuring of fcc metal surfaces resulting in a composite patterned morphology. On the other hand, co-adsorbed metal atoms and organic molecules often form extended 2D networks due to the metal-molecular coordination reaction. Here we report on a new type of structural modification of the molecule-substrate interface, which is not only restricted to self-assembly of the adsorbed metal atoms and molecules, but it also involves significant morphological reorganization of the metallic surface. In the experiments, potassium atoms are deposited on a monolayer of the long-range ordered PTCDA/Ag(110) phase. Subsequent annealing forces potassium atoms to intercalate under the molecular layer partially unbinding PTCDA from the substrate. The complex interaction between potassium, PTCDA and substrate induces a significant silver mass-transfer and leads to the appearance of 1D stripe-structures of K atoms and PTCDA molecules on a nanopatterned silver surface. Structural and electronic properties of this pattern were studied by means of NIXSW, XPS, LEED and LT-STM.

  12. Investigation on the adsorption of phosphorus by Fe-loaded ceramic adsorbent.

    Wang, Di; Chen, Nan; Yu, Yang; Hu, Weiwu; Feng, Chuanping

    2016-02-15

    This aim of this study was to remove phosphorus from aqueous solution using a Fe-loaded ceramic (Fe-LC) adsorbent prepared by mixing dolomite, montmorillonite, FeSO4·7H2O and starch. Simplex-centroid mixture design method was used to determine the optimum mixture proportions by evaluating both phosphorus adsorption efficiency and adsorbent hardness. The study found that the optimum adsorption capacity and the strength can be achieved with the composition of 3.87g dolomite, 3.00g starch, 2.13g montmorillonite and 1.00g FeSO4·7H2O (10g in total). The optimized Fe-LC was evaluated in the batch and the fixed bed experiments. The point of zero charge, pHpzc was found to be 6.0. The adsorption kinetic and isotherm data well agreed with the pseudo-second-order kinetic and the Langmuir isotherm models, respectively. The breakthrough time increased with increasing in the bed depth, whereas inverse relationship was observed with the initial phosphorus concentration in the fixed bed studies. The co-existing anions (SO4(2-), NO3(-) and Cl(-)) had negligible influence on phosphorus removal. The BDST and Thomas model explained the breakthrough behavior for phosphorus removal with a high degree of correlation. PMID:26624533

  13. Hybrid materials: Magnetite-Polyethylenimine-Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment.

    Larraza, Iñigo; López-Gónzalez, Mar; Corrales, Teresa; Marcelo, Gema

    2012-11-01

    Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40 nm, Fe(3)O(4) NPs) coated with Polyethylenimine polymer (PEI 800 g/mol or PEI 25000 g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe(3)O(4) NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1-9). A maximum amount of adsorption capacity of 8.8 mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH. PMID:22841705

  14. Adsorbent for p-phenylenediamine adsorption and removal based on graphene oxide functionalized with magnetic cyclodextrin

    Wang, Dongxue; Liu, Liangliang; Jiang, Xinyu; Yu, Jingang; Chen, Xiaohong; Chen, Xiaoqing

    2015-02-01

    Recently, graphene oxide (GO) based magnetic nanocomposites have been widely used in an adsorption-based process for the removal of organic pollutants from the water system. In this study, magnetic β-cyclodextrin-graphene oxide nanocomposites (MCG) were synthesized according to covalent binding of magnetic β-cyclodextrin nanoparticles onto the GO surface and the as-made nanocomposites were successfully applied as adsorbents for the adsorption and removal of p-phenylenediamines (PPD). The composition and morphology of prepared materials were characterized by Fourier infrared spectrometry (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Effects of pH, temperature, time and reusability on the adsorption of PPD were investigated, as well as the kinetics and isotherms parameters of the adsorbents were determined. The results indicated that the maximum adsorption capacity of MCG was 1102.58 mg/g at 45 °C and pH 8. The adsorption capacity remained at 81% after five cycles. Removal rate could reach 98% after three times of adsorption. The adsorption process with PPD was found that fitted pseudo-second-order kinetics equations and the Langmuir adsorption model. The results showed the MCG had a good adsorption ability to remove organic pollutants in wastewater.

  15. Removal of Cu (II and Zn (II from water with natural adsorbents from cassava agroindustry residues

    Daniel Schwantes

    2015-07-01

    Full Text Available Current study employs solid residues from the processing industry of the cassava (Manihot esculenta Crantz (bark, bagasse and bark + bagasse as natural adsorbents for the removal of metal ions Cu(II and Zn(II from contaminated water. The first stage comprised surface morphological characterization (SEM, determination of functional groups (IR, point of zero charge and the composition of naturally existent minerals in the biomass. Further, tests were carried out to evaluate the sorption process by kinetic, equilibrium and thermodynamic studies. The adsorbents showed a surface with favorable adsorption characteristics, with adsorption sites possibly derived from lignin, cellulose and hemicellulose. The dynamic equilibrium time for adsorption was 60 min. Results followed pseudo-second-order, Langmuir and Dubinin-Radushkevich models, suggesting a chemisorption monolayer. The thermodynamic parameters suggested that the biosorption process of Cu and Zn was endothermic, spontaneous or independent according to conditions. Results showed that the studied materials were potential biosorbents in the decontamination of water contaminated by Cu(II and Zn(II. Thus, the above practice complements the final stages of the cassava production chain of cassava, with a new disposal of solid residues from the cassava agroindustry activity.

  16. Composite Coatings with Ceramic Matrix Including Nanomaterials as Solid Lubricants for Oil-Less Automotive Applications

    Posmyk A.

    2016-06-01

    Full Text Available The paper presents the theoretical basis of manufacturing and chosen applications of composite coatings with ceramic matrix containing nanomaterials as a solid lubricant (AHC+NL. From a theoretical point of view, in order to reduce the friction coefficient of sliding contacts, two materials are required, i.e. one with a high hardness and the other with low shear strength. In case of composite coatings AHC+NL the matrix is a very hard and wear resistant anodic oxide coating (AHC whereas the solid lubricant used is the nanomaterial (NL featuring a low shear strength such as glassy carbon nanotubes (GC. Friction coefficient of cast iron GJL-350 sliding against the coating itself is much higher (0.18-0.22 than when it slides against a composite coating (0.08-0.14. It is possible to reduce the friction due to the presence of carbon nanotubes, or metal nanowires.

  17. Preparation of Urea Nitrogen Adsorbent of Complex Type and Adsorption Capacity of Urea Nitrogen onto the Adsorbent

    2006-01-01

    The urea nitroge n adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose (CDAC) and immobilized urease in gelatin membrane (IE), was prepared. The cellulose, the dialdehyde cellulose (DAC) and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10:1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37 ℃.

  18. Study of Adsorbents for the Capture of CO2 in Post-combustion. Contribution of CIEMAT to Module 4 of the CENITCO2 Project

    The main goal of CIEMAT within the CENIT-CO2 project has been the development of a process for CO2 capture from combustion flue gases by physical adsorption. In the first stage, screening studies to select promising adsorbents were carried out at laboratory scale, using simplified gas compositions. After that, pilot plant studies were performed using appropriate configurations of promising adsorbents under realistic conditions. CO2 adsorption cyclic capacity of different adsorbents has been studied. Lastly, for the adsorbent selected as most promising, its cyclic efficiency and selectivity for CO2 adsorption in the presence of other gaseous components (SO2, H2O, NO) of the combustion gas has been determined, as well as its performance along multiple sorption-desorption cycles in the presence of simulated combustion gas. None of the studied adsorbents, though being promising since they all have a capture efficiency of about 90%, seem to be susceptible of direct application to CO2 capture by physical adsorption under conditions representative of gases exiting the desulphurization tower of conventional pulverized coal combustion plants. As an alternative, the development of hybrid and regenerable solid sorbents (physical-chemical adsorption) is proposed or the application of new technologies under development such as the electrochemical promotion in capturing CO2. (Author) 33 refs.

  19. Facile preparation of magnetic separable powdered-activated-carbon/Ni adsorbent and its application in removal of perfluorooctane sulfonate (PFOS) from aqueous solution.

    Liang, Xuanqi; Gondal, Mohammed A; Chang, Xiaofeng; Yamani, Zain H; Li, Nianwu; Lu, Hongling; Ji, Guangbin

    2011-01-01

    The main aim of this study was to synthesize magnetic separable Nickel/powdered activated carbon (Ni/PAC) and its application as an adsorbent for removal of PFOS from aqueous solution. In this work, the synthesized adsorbent using simple method was characterized by using X-ray diffractionometer (XRD), surface area and pore size analyzer, vibrating sample magnetometer (VSM), and high resolution transmission electron microscope (HRTEM). The surface area, pore volume and pore size of synthesized PAC was 1521.8 m(2)g(-1), 0.96 cm(3)g(-1), 2.54 nm, respectively. Different kinetic models: the pseudo-first-order model, the pseudo-second-order model, and three adsorption isotherms--Langmuir, Freundlich and Temkin--were applied to study the sorption kinetics and isothermal behavior of PFOS onto the surface of an as-prepared adsorbent. The rate constant using the pseudo-second-order model for removal of 150 ppm PFOS was estimated as 8.82×10(-5) and 1.64×10(-4) for PAC and 40% Ni/PAC, respectively. Our results demonstrated that the composite adsorbents exhibited a clear magnetic hysteretic behavior, indicating the potential practical application in magnetic separation of adsorbents from aqueous solution phase as well. PMID:21961696

  20. Tantalum oxide coatings as candidate environmental barriers

    Moldovan, Monica; Weyant, C. M.; Johnson, D. Lynn; Faber, K. T.

    2004-01-01

    Tantalum (Ta) oxide, due to its high-temperature capabilities and thermal expansion coefficient similar to silicon nitride, is a promising candidate for environmental barriers for silicon (Si) nitride-based ceramics. This paper focuses on the development of plasma-sprayed Ta oxide as an environmental barrier coating for silicon nitride. Using a D-optimal design of experiments, plasma-spray processing variables were optimized to maximize coating density. The effect of processing variables on c...

  1. Applications of Oxide Coatings in Photovoltaic Devices

    Sonya Calnan

    2014-03-01

    Full Text Available Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ≥1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported.

  2. Nanostructured niobium oxide coatings influence osteoblast adhesion.

    Eisenbarth, E; Velten, D; Müller, M; Thull, R; Breme, J

    2006-10-01

    The interaction of osteoblasts was correlated to the roughness of nanosized surface structures of Nb(2)O(5) coatings on polished CP titanium grade 2. Nb(2)O(5) sol-gel coatings were selected as a model surface to study the interaction of osteoblasts with nanosized surface structures. The surface roughness was quantified by determination of the average surface finish (Ra number) by means of atomic force microscopy. Surface topographies with Ra = 7, 15, and 40 nm were adjusted by means of the annealing process parameters (time and temperature) within a sol-gel coating procedure. The observed osteoblast migration was fastest on smooth surfaces with Ra = 7 nm. The adhesion strength, spreading area, and collagen-I synthesis showed the best results on an intermediate roughness of Ra = 15 nm. The surface roughness of Ra = 40 nm was rather peaked and reduced the speed of cell reactions belonging to the adhesion process. PMID:16788971

  3. Evaluation of natural clay Brasgel as adsorbent in removal of lead in synthetic waste water

    The smectite clays have high adsorption capacity and cation exchange. Due to its chemical and physical characteristics, they can be effectively used as adsorbent of pollutants (such as metal ions). The initial objective of this study was to characterize the clay Brasgel through the techniques of X-Ray Diffraction (XRD), X-Ray Spectrometry by Energy Dispersive (EDX) and nitrogen adsorption (BET method), seeking its use in removing lead (Pb2+) from synthetic effluents. System was used in finite bath to assess the potential removal of lead (Pb2+), following a 22 factorial experimental design with three center point experiments, taking as input variables: pH and initial concentrations of lead (Pb2+). The clay has Brasgel clay in its composition that characterize it as a smectite clay. By having a large surface area, this clay showed great potential on the adsorption of metal ions. (author)

  4. Removal of acutely hazardous pharmaceuticals from water using multi-template imprinted polymer adsorbent.

    Venkatesh, Avinash; Chopra, Nikita; Krupadam, Reddithota J

    2014-05-01

    Molecularly imprinted polymer adsorbent has been prepared to remove a group of recalcitrant and acutely hazardous (p-type) chemicals from water and wastewaters. The polymer adsorbent exhibited twofold higher adsorption capacity than the commercially used polystyrene divinylbenzene resin (XAD) and powdered activated carbon adsorbents. Higher adsorption capacity of the polymer adsorbent was explained on the basis of high specific surface area formed during molecular imprinting process. Freundlich isotherms drawn showed that the adsorption of p-type chemicals onto polymer adsorbent was kinetically faster than the other reference adsorbents. Matrix effect on adsorption of p-type chemicals was minimal, and also polymer adsorbent was amenable to regeneration by washing with water/methanol (3:1, v/v) solution. The polymer adsorbent was unaltered in its adsorption capacity up to 10 cycles of adsorption and desorption, which will be more desirable in cost reduction of treatment compared with single-time-use activated carbon. PMID:24499987

  5. Adsorbed molecules in external fields: Effect of confining potential.

    Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

    2016-12-01

    We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials. PMID:27387127

  6. Ordered molecular layer structure of lubricating oil adsorbed films

    2001-01-01

    Low-angle X-ray diffraction has been applied to analyze the structure of stearic acid LB films and self-grown surface adsorbed films of aluminium product metalworking lubricants. The results show that LB films exhibit a good layer-like ordered structure in the normal direction of film-carrying surface, while in the tangential direction, they do not show a cyclically ordered molecular arrangement; as for the self-grown surface adsorbed films of aluminium sheet and strip metalworking lubricants, their molecules are orderly arranged to certain degree in both the tangential and the normal directions of film-carrying surface, and they have a short-range ordered structure. Moreover, the better the orientation of normal molecules is, the higher the oil film strength is, and the smaller the friction factor is.

  7. Radiolysis of alanine adsorbed in a clay mineral

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine

  8. Forces and pressures in adsorbing partially directed walks

    Janse van Rensburg, E. J.; Prellberg, T.

    2016-05-01

    Polymers in confined spaces lose conformational entropy. This induces a net repulsive entropic force on the walls of the confining space. A model for this phenomenon is a lattice walk between confining walls, and in this paper a model of an adsorbing partially directed walk is used. The walk is placed in a half square lattice {{{L}}}+2 with boundary \\partial {{{L}}}+2, and confined between two vertical parallel walls, which are vertical lines in the lattice, a distance w apart. The free energy of the walk is determined, as a function of w, for walks with endpoints in the confining walls and adsorbing in \\partial {{{L}}}+2. This gives the entropic force on the confining walls as a function of w. It is shown that there are zero force points in this model and the locations of these points are determined, in some cases exactly, and in other cases asymptotically.

  9. Determination of Cr and Cd concentration adsorbed by chicken feathers

    In this work the results of the samples analysis of chicken feathers are presented, used as adsorber of the heavy metals Cd and Cr present in water solutions with well-known concentrations of these metals. It was used the Neutron Activation Analysis technique (AAN), using the TRIGA Mark-III reactor of the Nuclear Center of Mexico. The obtained results they show the advantages of having a versatile installation for the analysis of this type of samples. By means of the analysis of the results, it was determined the feasibility of using chicken feathers like adsorber of these metals present in polluted waters, additionally, it was detected the presence of others polluting elements in the inputs to prepare the reference solutions as well as in the processes, so much of preparation of the feathers like of the metals adsorption. (Author)

  10. Adsorbed self-avoiding walks subject to a force

    We consider a self-avoiding walk model of polymer adsorption where the adsorbed polymer can be desorbed by the application of a force. In this paper the force is applied normal to the surface at the last vertex of the walk. We prove that the appropriate limiting free energy exists where there is an applied force and a surface potential term, and prove that this free energy is convex in appropriate variables. We then derive an expression for the limiting free energy in terms of the free energy without a force and the free energy with no surface interaction. Finally we show that there is a phase boundary between the adsorbed phase and the desorbed phase in the presence of a force, prove some qualitative properties of this boundary and derive bounds on the location of the boundary. (paper)

  11. Adsorbed self-avoiding walks subject to a force

    Janse van Rensburg, E. J.; Whittington, S. G.

    2013-11-01

    We consider a self-avoiding walk model of polymer adsorption where the adsorbed polymer can be desorbed by the application of a force. In this paper the force is applied normal to the surface at the last vertex of the walk. We prove that the appropriate limiting free energy exists where there is an applied force and a surface potential term, and prove that this free energy is convex in appropriate variables. We then derive an expression for the limiting free energy in terms of the free energy without a force and the free energy with no surface interaction. Finally we show that there is a phase boundary between the adsorbed phase and the desorbed phase in the presence of a force, prove some qualitative properties of this boundary and derive bounds on the location of the boundary.

  12. Plant waste materials from restaurants as the adsorbents for dyes

    Pavlović Marija D.

    2015-01-01

    Full Text Available This paper has demonstrated the valorization of inexpensive and readily available restaurant waste containing most consumed food and beverage residues as adsorbents for methylene blue dye. Coffee, tea, lettuce and citrus waste have been utilized without any pre-treatment, thus the adsorption capacities and dye removal efficiency were determined. Coffee waste showed highest adsorbent capacity, followed by tea, lettuce and citrus waste. The dye removal was more effective as dye concentration increases from 5 up to 60 mg/L. The favorable results obtained for lettuce waste have been especially encouraged, as this material has not been commonly employed for sorption purposes. Equilibrium data fitted very well in a Freundlich isotherm model, whereas pseudo-second-order kinetic model describes the process behavior. Restaurant waste performed rapid dye removal at no cost, so it can be adopted and widely used in industries for contaminated water treatment.

  13. Molecular origins of friction. The force on adsorbed layers

    Cieplak, M.; Smith, E.D.; Robbins, M.O. [Johns Hopkins Univ, Baltimore, MD (United States)

    1994-08-01

    Simulations and perturbation theory are used to study the molecular origins of an ideal model system, a layer of adsorbed molecules sliding over a substrate. These calculations reproduce several surprising features of experimental results. In most cases, the frictional force on a solid monolayer has a different form from that observed between macroscopic solids. No threshold force or static friction is needed to initiate sliding; instead, the velocity is proportional to the force. As in experiments, incommensurate solid layers actually slide more readily than fluid layers. A comparison of experiment, simulation, and analytic results shows that dissipation arises from anharmonic coupling between phonon modes and substrate-induced deformations in the adsorbate. 19 refs.

  14. Development of high temperature adsorbent in PWR primary system

    Radiation exposure reduction in PWR is one of the most important problems to be solved. We have developed a high temperature Co adsorbent (HTA), which could be directly applied under primary reactor coolant conditions. This adsorbent was Fe-Ti-O system ceramics, and was fabricated to a suitable form for using in a packed column. Through those experiments of adsorption tests, compatibility tests, leaching tests and hot loop tests, it was found that HTA had superior adsorption capability to not only Co and Ni-ion but also many other transition metal ions. And it was also found that HTA was compatible with high temperature water, as well as advantageous for its waste solidification. Based on the experimental results, dose reduction effect was evaluated by a computer code. From this evaluation, it was found that more than 50 % dose reduction could be expected, when an advanced reactor coolant clean-up (RCC) system with HTA would be realized. (author)

  15. Development of adsorber system utilizing ocean current for uranium recovery from seawater

    Based on the concept of adsorber previously proposed by some of the present authors, a submarine adsorber system utilizing the energy of ocean current was proposed. In order to make the concept of adsorber practical, the system design was made by taking into account the support of equipment in the sea, the equipment structure, the packed bed of adsorbents, the mooring method and the replacement of adsorbents. An estimation equation of adsorber cost was derived for the present type of adsorber. The optimum dimensions of adsorber were determined under the restrictions such as the size of dock in a shipbuilding factory and the stability in towing and mooring the equipment. The calculated results suggested that the adsorber cost decreased by around 30 % under the optimum condition. And the transportation system of the adsorbent was investigated. In the case where a mother ship system was adopted, the transportation cost was 5,000 yen/ton-adsorbent. It was made clear that the total recovery cost of uranium from the seawater could be reduced to 140,000 yen/kg-U from 190,000 yen/kg-U based on the above consideration. It was also considered necessary to further improve the adsorption capacity of adsorbent in order to realize a sharp reduction in the recovery cost of uranium. (author)

  16. Sulfometuron incorporation in cationic micelles adsorbed on montmorillonite

    Mishael, Y. G.; Undabeytia López, Tomás; Rytwo, Giora; Papahadjopoulos Sternberg, B.; Rubin, Baruch; Nir, Shlomo

    2002-01-01

    The aim of this study was to understand the interactions between alkylammonium cations present as monomers and micelles and a clay mineral, montmorillonite, to develop slow release formulations of anionic herbicides, such as sulfometuron (SFM) whose leaching in soils is an environmental and economic problem. In the proposed formulation the herbicide is incorporated in positively charged micelles of quaternary amine cations, which in turn adsorb on the negatively charged clay. The adsorption o...

  17. Removing 3,5-Dichlorophenol from Wastewater by Alternative Adsorbents

    Kobetičová Hana; Galbičková Blanka; Ševčíková Janka; Soldán Maroš

    2014-01-01

    The main objective of this paper is to evaluate an efficiency of 3,5 - dichlorophenol removal from wastewater by using alternative adsorbents. Chlorophenols are organic compounds consisting of a benzene ring, OH groups and also atoms of chlorine. Chlorophenols may have a huge isomere variety that means there are differences in their chemical and physical properties. Due to their toxicity it is necessary to remove them from waste water and in this paper an alternative way of such process is de...

  18. PREPARATION OF CHITOSAN COATED METAL AFFINITY CHROMATOGRAPHY ADSORBENT

    AanTianwei; XuWeijiang; 等

    1998-01-01

    A new and an inexpensive adsorbent of chitosan coated silica for immobilized metal affinity chromatography(IMAC) was studied.After a double coating,the chitosan coated on silica beads could be up to 53.4mg/g silica beads.When pH>3.8,the metal ligand Cu2+ was chelated on the coated chitosan with a bound capacity of 14.6mg/g chitosan without introducing iminodiacetic acid(IDA).

  19. Linear response theory of activated surface diffusion with interacting adsorbates

    Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

  20. Toxicity of Uranium Adsorbent Materials using the Microtox Toxicity Test

    Park, Jiyeon [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jeters, Robert T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bonheyo, George T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-01

    The Marine Sciences Laboratory at the Pacific Northwest National Laboratory evaluated the toxicity of a diverse range of natural and synthetic materials used to extract uranium from seawater. The uranium adsorbent materials are being developed as part of the U. S. Department of Energy, Office of Nuclear Energy, Fuel Resources Program. The goal of this effort was to identify whether deployment of a farm of these materials into the marine environment would have any toxic effects on marine organisms.

  1. Onion membrane: an efficient adsorbent for decoloring of wastewater

    Saber-Samandari, Samaneh; Heydaripour, Jalil

    2015-01-01

    Background Recently, researchers have tried to design synthetic materials by replicating natural materials as an adsorbent for removing various types of environmental pollutants, which have reached to the risky levels in nature for many countries in the world. In this research, the potential of onion membrane obtained from intermediate of onion shells for adsorption of methylene blue (MB) as a model cationic dye was exhibited. Methods Before and after adsorption, the membrane was characterize...

  2. Dynamic scanning probe microscopy of adsorbed molecules on graphite

    Berdunov, N.; Pollard, A J; Beton, P. H.

    2008-01-01

    We have used a combined dynamic scanning tunneling and atomic force microscope to study the organisation of weakly bound adsorbed molecules on a graphite substrate. Specifically we have acquired images of islands of the perylene derivative molecules. These weakly bound molecules may be imaged in dynamic STM, in which the probe is oscillated above the surface. We show that molecular resolution may be readily attained and that a similar mode of imaging may be realised using conventional STM arr...

  3. Equipment review: The molecular adsorbents recirculating system (MARS®)

    Boyle, Martin; Kurtovic, Jelica; Bihari, David; Riordan, Stephen; Steiner, Christian

    2004-01-01

    The molecular adsorbents recirculating system (MARS®) is a form of artificial liver support that has the potential to remove substantial quantities of albumin-bound toxins that have been postulated to contribute to the pathogenesis of liver cell damage, haemodynamic instability and multi-organ failure in patients with acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF). These toxins include fatty acids, bile acids, tryptophan, bilirubin, aromatic amino acids and nitric oxide....

  4. A Review of Adsorbents Used for Storm Water Runoff Cleaning

    Andrius Agintas; Marina Valentukevičienė

    2011-01-01

    Heavy metals, petroleum products, sediments and other pollutants get in the environment with insufficiently cleaned storm water runoff. Contaminated storm water runoff is one of the most significant sources for pollution in rivers, lakes and estuaries. Storm water runoff must be treated using not only simple methods but also using adsorption processes. Adsorbents can be natural organic, natural nonorganic and synthetic. Main adsorption characteristic, way of utilization and storm water runoff...

  5. Preparation of lignin derivatives and their application as protease adsorbents

    Xian-Su Cheng; Yin Lin; Run Fang

    2009-01-01

    Synthesis of two lignin derivatives, lignophenol and lignin-aminophenol, were presented in this article. The chemical structure and the func-tional groups of lignin derivatives were charac-terized through FT-IR analysis. The immobiliza-tion of three proteases (papain, trypsin and pepsin) on lignin and lignin derivatives was carried out using adsorption technique. The influence of contact time and pH on the enzyme adsorption by different adsorbents was inves-tigated. Furthermore, enzyme activi...

  6. Non-linear optical studies of adsorbates: Spectroscopy and dynamics

    In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs

  7. Silver diffusion over silicon surfaces with adsorbed tin atoms

    Silver diffusion over the (111), (100), and (110) surfaces of silicon with preliminarily adsorbed tin atoms is studied by Auger electron spectroscopy and low-energy electron diffraction. Diffusion is observed only on the surface of Si(111)-2√3 × 2√3-Sn. The diffusion mechanism is established. It is found that the diffusion coefficient depends on the concentration of diffusing atoms. The diffusion coefficient decreases with increasing silver concentration, while the activation energy and the preexponential factor increase

  8. Adsorption capacity of various adsorbents for decolorization of wastewater

    Romčević, Gorana

    2014-01-01

    Adsorption is applied for the removal of dyes from wastewater effluent from textile and other industries. Dyes from wastewater need to be removed before it mixes with water bodies. Among the treatment options, adsorption appears to have considerable potential for the removal of colour from wastewaters. Activated carbon is the most widely used adsorbent, but its use is limited due to its high cost. This cost problem has led to a search for the use of alternate cheap and efficient materials. ...

  9. Fate of adsorbable micropollutants through sludge drying and composting processes

    Besnault, S.; Martin Ruel, S.; Choubert, JM.; Budzinski, H.; Miege, C.; Esperanza, M.; Noyon, N.; Garnaud, S.; Coquery, M.

    2012-01-01

    The objective of the paper was to evaluate the fate of 79 adsorbed micropollutants through 9 sludge treatment processes. A specific sampling strategy was applied to follow a “batch” of sludge through the treatment (inlet and outlet sludge, intermediary mixture for some processes such as composting and condensates). Mass balances were established to calculate micropollutants removal efficiencies and the fate of the substances through these facilities was evaluated. In order to limi...

  10. Non-linear optical studies of adsorbates: Spectroscopy and dynamics

    Zhu, Xiangdong.

    1989-08-01

    In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. The qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs.

  11. Fixed-bed adsorption separation of xylene isomers over sio2/silicallite-1 core-shell adsorbents

    Khan, Easir A.

    2013-12-29

    SiO2/Silicalite-1 core-shell material has been demonstrated as potential shape selective adsorbent in gas phase separation of p-xylene from a mixture of p/o-xylene isomers. The core-shell composite comprised of large silica core and thin polycrystalline silicalite-1 shell which was synthesized via a self-assembly of silicalite-1 nanocrystals on core silica surface followed by a secondary seeded growth method. The core materials, SiO2 used in this study has mesoporosity with an average pore diameter of 60Å and hence offers no shape selectivity for xylene isomers. However, the shell, silicalite-1 contains rigid pore structures and preferentially adsorbs p-xylene from their isomers mixtures. A series of adsorption fixed bed breakthrough adsorption/desorption experiment was performed to obtain the equilibrium isotherms and adsorption isotherm parameters of xylene isomers. The equilibrium isotherms of xylene isomers follow the Langmuir\\'s model. A chromatographic adsorption model has been used to describe the fixed-bed breakthrough profiles of xylene isomers. The model has successfully predicted the responses of the binary mixtures of p/o-xylene isomers. The SiO2/silicalite-1 core-shell adsorbents have shown para-selectivity as high as 15. © Bangladesh Uni. of Engg. & Tech.

  12. Development Trends in Porous Adsorbents for Carbon Capture.

    Sreenivasulu, Bolisetty; Sreedhar, Inkollu; Suresh, Pathi; Raghavan, Kondapuram Vijaya

    2015-11-01

    Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments. PMID:26422294

  13. Two dimensional condensation of argon adsorbed on lamellar halides

    Lamellar halides such as NiCl2, FeCl2, NiBr2, MnBr2, MgBr2, CdBr2, CoI2, FeI2, MnI2, CaI2 and PbI2 were sublimed in a rapid stream of dry nitrogen. The adsorption of argon on such materials shows stepped isotherms which reveal two dimensional condensations. From sets of isotherms the Helmholtz free energy, the internal energy and the entropy of the successive layers are determined. From the entropy of the first layer the role of the potential relief of the adsorbent surface on the structure of the adsorbed layer may be determined while the Helmholtz free energy reveals how the ionic character of the adsorbent governs the attractive force of adsorption. The study of the second third and fourth layers shows that their growth follows quite a different behaviour depending on whether the Van der Waals diameter of argon is greater or smaller than the distance between adjacent anions on the crystal surface. A proposition is made to account for the difference in the critical temperatures of the first and second dense layers in terms of the vibrationnal state of their respective substrate. The occurence for the maximum critical temperature observed of corresponding to a triangular layer 3% more expanded than the (111) plane of solid argon is discussed

  14. Regeneration of thiol-functionalized mesostructured silica adsorbents of mercury

    Arencibia, Amaya; Aguado, José; Arsuaga, Jesús M.

    2010-06-01

    The regeneration of thiol-functionalized SBA-15 adsorbents of mercury is presented in this article. The influence of temperature and pH on the adsorption process was studied. The effect due to the presence of complexing agents in aqueous solution on the desorption step was also evaluated. Hg(II) maximum adsorption capacities at different temperatures ranging from 20 °C to 60 °C were obtained and it was found that temperature does not affect the adsorption process. Mercury adsorption capacity was also determined in the presence of HNO 3 and HCl up to 3 M concentration. The comparison of the results showed that whereas hydrochloric acid exhibits an appreciable capacity to regenerate the thiol-functionalized SBA-15 adsorbent, the nitric acid results inefficient. The difference was attributed to the mercury complexing ability of chloride anion. Four complexing compounds, KBr, KSCN, (NH 2) 2CS, and HBr were tested for desorbing mercury in regeneration experiments. All agents were able to remove significant amounts of adsorbed mercury, being hydrobromic acid the complexing compound that yields the best results.

  15. Distribution of metal and adsorbed guest species in zeolites

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes 129Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of 129Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, 129Xe NMR is insensitive to fine structural details at room temperature

  16. The influence of frequency on fractal dimension of adsorbed layers

    Alternating current (AC) voltammetry and electrochemical impedance spectroscopy are often the methods of choice for use in study of adsorption of organic molecules. The adsorption of organic molecules on interface may result in the formation of fractal structures, whose fractal dimension can be estimated using the method of scaling the hanging mercury drop electrode (HMDE). The aim of present study was to check whether the estimated fractal dimension, D (or for that matter the fractal ordering of the adsorbed layer) shows any correlation (dependence) with change of applied frequency, and second, to check the possibility to extend the method to broad frequency spectrum compatible with impedance spectroscopy. The investigation included two surfactants nonionic Triton-X-100 (T-X-100) and anionic sodium dodecyl sulfate (SDS) and alcohol tert-butanol. All measurements were performed on HMDE at thermodynamic equilibrium employing broad frequency spectrum. The validity of the approach was checked by measurements on pure electrolyte and by comparison with previously obtained results for fractal layers. The results of the investigations show that: (1) the method of scaling the HMDE to obtain the fractal dimension of adsorbed layer is compatible with impedance spectroscopy and the combination of these methods can be used as a powerful tool to investigate fractal aspect of adsorption of organic molecules; (2) fractal ordering of adsorbed layer and the value of fractal dimension is not influenced by the frequency of applied sinusoidal voltage perturbations

  17. Specific binding-adsorbent assay method and test means

    A description is given of an improved specific binding assay method and test means employing a nonspecific adsorbent for the substance to be determined, particularly hepatitis B surface (HBsub(s)) antigen, in its free state or additionally in the form of its immune complex. The invention is illustrated by 1) the radioimmunoadsorbent assay for HBsub(s) antigen, 2) the radioimmunoadsorbent assay for HBsub(s) antigen in the form of immune complex with antibody, 3) a study of adsorption characteristics of various anion exchange materials for HBsub(s) antigen, 4) the use of hydrophobic adsorbents in a radioimmunoadsorbent assay for HBsub(s) antigen and 5) the radioimmunoadsorbent assay for antibody to HBsub(s) antigen. The advantages of the present method for detecting HBsub(s) antigen compared to previous methods include the manufacturing advantages of eliminating the need for insolubilised anti-HBsub(s) and the advantages of a single incubation step, fewer manipulations, storability of adsorbent materials, increased sensitivity and versatility of detecting HBsub(s) antigen in the form of its immune complex if desired. (U.K.)

  18. Photoinduced surface dynamics of CO adsorbed on a platinum electrode.

    Noguchi, Hidenori; Okada, Tsubasa; Uosaki, Kohei

    2006-08-10

    The surface dynamics of adsorbed CO molecules formed by dissociative adsorption of HCHO at a polycrystalline Pt electrode/electrolyte solution interface was studied by picosecond time-resolved sum-frequency generation (TR-SFG) spectroscopy. A SFG peak at 2050-2060 cm(-1) was observed at the Pt electrode in HClO(4) solution containing HCHO at 0-300 mV (vs Ag/AgCl), indicating the formation of adsorbed CO at an atop site of the Pt surface as a result of dissociative adsorption of HCHO. The peak position varied with potential by approximately 33 cm(-1)/V, as previously found in an infrared reflection absorption spectroscopy (IRAS) study. Irradiation of an intense picosecond visible pulse (25 ps, 532 nm) caused an instant intensity decrease and broadening of the CO peak accompanied by the emergence of a new broad peak at approximately 1980 cm(-1) within the time resolution of the system. These results suggest a decrease and increase in the populations of CO adsorbed on atop and bridge sites, respectively, upon visible pump pulse irradiation. PMID:16884215

  19. Distribution of metal and adsorbed guest species in zeolites

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  20. Preparation of core-shell Fe3O4/SiO2 microspheres as adsorbents for purification of DNA

    Nearly monodisperse core-shell Fe3O4/SiO2 microspheres have been prepared via a glycol reduction method followed by a modified Stoeber process. The thickness of the silica shells can be tuned in the range 33-53 nm by varying the amount of tetraethyl silicate (TEOS) during syntheses. The magnetic composite microspheres were characterized with XRD, XPS, FTIR, TEM, ICP-OES and VSM, and further tested as adsorbents for purification of plasmid DNA from Escherichia coli DH5α cells. The magnetic purification of plasmid DNA leads to satisfying integrity, yield and purity in comparison with those isolated by the traditional phenol-chloroform extraction.

  1. Constructing a proton titration curve from ion-step measurements, applied to a membrane with adsorbed protein

    Eijkel, Jan C. T.; Bosch, Coen; Olthuis, Wouter; Bergveld, Piet

    1997-01-01

    A new measuring method is described for obtaining a proton titration curve. The curve is obtained from a microporous composite membrane, consisting of polystyrene beads in an agarose matrix, with lysozyme molecules adsorbed to the bead surface. The membrane is incorporated into a sensor system by deposition on a silicon chip with a pH-sensitive ion-sensitive field effect transistor (ISFET) located in the middle of a Ag/AgCl electrode. The actual measurement is performed by creating a stepwise...

  2. Dynamic separation of Szilard-Chalmers reaction products applied to the trioxalatochromium ion adsorbed on anionic exchange resin

    A method of dynamic elution of recoiled 51Cr+3, formed by the Szilard-Chalmers reaction during the irradiation of trioxalatochromium ion adsorbed on anionic exchange resin is presented. The influence of some factors on the separation yield of chromium-51, such as: composition, concentration and flow rate of eluent, mesh size of the resin and irradiation time are studied. The results are compardd with those obtained by the static method, in which the recoiled atom is separated from the target after irradiation. Because of the high separation yield of chromium-51, the method of dynamic separation is proposed for routine production of this elemnt, with high specific activities. (author)

  3. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  4. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  5. Electric field cancellation on quartz: a Rb adsorbate induced negative electron affinity surface

    Sedlacek, J A; Rittenhouse, S T; Weck, P F; Sadeghpour, H R; Shaffer, J P

    2015-01-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric fields resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the adsorbed Rb induces a negative electron affinity (NEA) on the quartz surface. The NEA surface allows low energy electrons to bind to the surface and cancel the electric field from the Rb adsorbates. Our results are important for integrating Rydberg atoms into hybrid quantum systems and the fundamental study of atom-surface interactions, as well as applications for electrons bound to a 2D surface.

  6. Electric Field Cancellation on Quartz by Rb Adsorbate-Induced Negative Electron Affinity

    Sedlacek, J. A.; Kim, E.; Rittenhouse, S. T.; Weck, P. F.; Sadeghpour, H. R.; Shaffer, J. P.

    2016-04-01

    We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric fields resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the adsorbed Rb induces negative electron affinity (NEA) on the quartz surface. The NEA surface allows low energy electrons to bind to the surface and cancel the electric field from the Rb adsorbates. Our results will be important for integrating Rydberg atoms into hybrid quantum systems, as fundamental probes of atom-surface interactions, and for studies of 2D electron gases bound to surfaces.

  7. Elimination of dyes from aqueous solutions using iron oxides and chitosan as adsorbents: a comparative study

    Silvina Pirillo

    2009-01-01

    Full Text Available This work investigates the adsorption of Alizarin, Eriochrome Blue Black R and Fluorescein using chitosan, goethite and magnetite as adsorbents. For Alizarin, the best adsorbent is chitosan with a Langmuir parameter of 15.8 mmol dye/g adsorbent. For Eriochrome Blue Black R only 1.94 mmol dye/g chitosan is adsorbed. Langmuir parameters for the Alizarin adsorption on both iron oxides display one or two orders of magnitude lower than for chitosan and two orders of magnitude lower in the case of Eriochrome Blue Black R. Fluorescein does not adsorb in appreciable amounts on chitosan and it presents the lower affinity on the iron oxides.

  8. Theoretical consideration on composite oxide scales and coatings

    HE Yedong; GAO Wei

    2013-01-01

    The present paper discussed some fundamental aspects on composite oxide scales and coatings for protection of alloys from high temperature oxidation,the related thermodynamic conditions,special mechanical characteristics and a sealing mechanism.It was proposed that the oxide scales and coatings with a composite structure should possess superior mechanical properties than that with a single phase oxide.It also showed that the A12O3 scales or coatings doped with Y2O3 and ZrO2 (or YSZ)-Al2O3 composite coatings possessed superior properties at high temperatures.In such composite oxide scales and coatings,the fracture resistance of the scales was increased by the toughening effect,the thermal stress was decreased owing to the increase of thermal-expansion coefficients,and Al2O3 phase could seal the alloy substrate well.In addition,the kinetic equation of thermal growth oxide on alloy covered with composite oxide coatings was derived.

  9. Recovery system for uranium from seawater with fibrous adsorbent and its preliminary cost estimation

    The cost of uranium recovered from seawater was estimated to extract the technical problems in the practical application of the fibrous amidoxime adsorbent synthesized by radiation graftpolymerization. Each cost of the adsorbent production, the dipping in seawater for uranium absorption, and the uranium elution from the adsorbent was estimated in three different mooring systems of a buoy, floating body, and chain binding system. The recovery cost was estimated to be 5-10 times of that from mining uranium. More than 80% of the total cost was occupied by the cost for marine equipment for mooring the adsorbents in seawater, which is owing to a weight of metal cage for adsorbents. Thus, the cost can be reduced to half by the reduction of the equipment weight to 1/4. The improvement of adsorbent ability is research subjects in the future also, since the cost directly depends on the adsorbent performance. (author)

  10. Amine-pillared Nanosheet Adsorbents for CO2 Capture Applications

    Jiang, Hui

    Amine-functionalized solid adsorbents have gained attention within the last decade for their application in carbon dioxide capture, due to their many advantages such as low energy cost for regeneration, tunable structure, elimination of corrosion problems, and additional advantages. However, one of the challenges facing this technology is to accomplish both high CO 2 capture capacity along with high CO2 diffusion rates concurrently. Current amine-based solid sorbents such as porous materials similar to SBA-15 have large pores diffusion entering molecules; however, the pores become clogged upon amine inclusion. To meet this challenge, our group's solution involves the creation of a new type of material which we are calling-amino-pillared nanosheet (APN) adsorbents which are generated from layered nanosheet precursors. These materials are being proposed because of their unique lamellar structure which exhibits ability to be modified by organic or inorganic pillars through consecutive swelling and pillaring steps to form large mesoporous interlayer spaces. After the expansion of the layer space through swelling and pillaring, the large pore space can be functionalized with amine groups. This selective functionalization is possible by the choice of amine group introduced. Our choice, large amine molecules, do not access the micropore within each layer; however, either physically or chemically immobilized onto the surface of the mesoporous interlayer space between each layer. The final goal of the research is to investigate the ability to prepare APN adsorbents from a model nanoporous layered materials including nanosheets precursor material MCM-22(P) and nanoporous layered silicate material AMH-3. MCM-22(P) contains 2-dimensional porous channels, 6 membered rings (MB) openings perpendicular to the layers and 10 MB channels in the plane of the layers. However, the transport limiting openings (6 MB) to the layers is smaller than CO2 gas molecules. In contrast, AMH-3 has

  11. Mixed waste: The treatment of organic radioactive waste by means of adsorbents

    Full text: The work described in this paper has been carried in the radioactive waste treatment facilities of the Nuclear Research Center Lo Aguirre, CEN LA, which are operated by Radioactive Waste Management Unit, UGDR. This last, centralizes its activities in order to manage all radioactive waste generated in the country due to the nuclear development. Features of danger and risks presented by organic radioactive liquid waste, make the need to develop a practicable alternative for its treatment and to allow the conditioning towards a suitable final disposal The raw material for this work, is an organic liquid waste arising from scintillation techniques, contaminated with Tritium. This mixed waste has to be treated and then conditioned in a solid form within a 200 I container, according with actual acceptance criteria for our temporary store for radioactive waste. The best formulation which allows to immobilize the liquid waste was determined. The first step consists in the adsorption treatment that waste is humbled. From the available adsorbents, two types were studied: adsorption granulat and diatomaceous earth. From the waste management standpoint, results with diatomaceous earth present physical characteristics better than the other Following, the second stage is the immobilization, which is achieved in a cement matrix made with puzzolanic cement (Polpaico 400) made in Chile. Later, due to cost and availability in the country, the diatomaceous earth is selected for the study, in the form of celite which is comparatively economic. The best mixture, with regard to physical feature, has the following composition: a 0.35 (w/w) water/cement ratio, which represents the needed quantity to obtain workability in the mixture, and it is the minimum amount of water to hydrating the cement; a waste/adsorbent ratio of 0.5 (v/v), in which the organic liquid is completely adsorbed and it is incorporated into the crystalline system of the solid form; and an adsorbed waste

  12. Bioavailability in rats of metal adsorbed to soils

    The toxicity of metals to humans and animals has been well documented, however little data are available on the physiological bioavailability of metals from various soil types. These studies were designed to assess the bioavailability of sodium 75selenate (NaS), 63nickel chloride (NiCl) and 109cadmium chloride (CdCl) adsorbed to sand or clay loam in rats. Each test compound was administered in seven dose groups: Group 1 - intravenously, Group 2 and 3 - oral aqueous solution by gavage, Groups 4-7 - aqueous suspension adsorbed to each soil type by gavage. Blood was collected from the jugular vein at intervals up to 48 hours post dosing and analyzed for radio-activity. Both NiCl and CdCl were poorly adsorbed from the soils. Approximately 3% of the CdCl bound to sand and 1.5% of the NiCl bound to clay loam were absorbed into the bloodstream. Approximately 0.5% and 0.1% of the CdCl bound to sand and clay, respectively were absorbed. NaS was well absorbed following oral administration with approximately 85% of the compound bound to sand and 94% bound to clay being absorbed into the blood. Bioavailability of metals from soil appears to be primarily affected by the ionic state of the metal. Anions, such as selenium, are more mobile in an acid environment and may leach more readily from soil. Cations, such as Ni and Cd may bind to soil more tightly, thus soil type becomes a factor affecting bioavailability

  13. Magnetically modified microbial cells: A new type of magnetic adsorbents

    Ivo Safarik; Mirka Safarikova

    2007-01-01

    Microbial cells, either in free or immobilized form, can be used for the preconcentration or removal of metal ions, organic and inorganic xenobiotics or biologically active compounds. Magnetic modification of these cells enables to prepare magnetic adsorbents that can be easily manipulated in difficult-to-handle samples, such as suspensions, in the presence of external magnetic field. In this review, typical examples of magnetic modifications of microbial cells are presented, as well as their possible applications for the separation of organic xenobiotics and heavy metal ions.

  14. Behavior of adsorbed Poly-A onto sodium montmorillonite

    Palomino-Aquino, Nayeli; Negrón-Mendoza, Alicia

    2015-07-01

    The adsorption of Poly-A (a polynucleotide consisting of adenine, ribose and a phosphate group), onto a clay mineral, was studied to investigate the extent of adsorption, the site of binding, and the capacity of the clay to protect Poly-A, while it is adsorbed onto the clay, from external sources of energy. The results showed that Poly-A presented a high percentage of adsorption at the edges of the clay and that the survival of the polynucleotide was superior to irradiating the polymer in the absence of the clay.

  15. Radiolysis of carboxylic acids adsorbed in clay minerals

    This research is aimed at studying the effect of ionizing radiation in an heterogeneous system formed by a carboxylic acid adsorbed in a clay mineral. The study is focussed to discriminate if the presence of a solid surface alters the formation and distribution of radiolytic products in relation to the radiolysis of the carboxylic acid without the surface (clay). The results showed that the radiolysis of the system clay-acid goes along a defined path rather than showing various pathways of decomposition as in the case of simple aqueous solutions. The main pathway was the decarboxylation of the target compound rather than condensation/dimerization reactions

  16. 3,5-Dichlorophenol Removal From Wastewater Using Alternative Adsorbents

    Kobetičová Hana

    2015-06-01

    Full Text Available The main objective of this paper is to evaluate the efficiency of 3,5-dichlorophenol removal from wastewater by using alternative low cost adsorbents. Waste from the production and processing of metals (black nickel mud, red mud and a biosorbent (Lemna minor were used for this research. Initial concentration of the contaminant was 4 mmol L−1, the contact time of sorbent and waste water was 0 - 48 hrs and the temperature during experiment was 25 ± 0.2 °C. The results show that the highest removal efficiency of 3,5 - dichlorophenol (58.18 % was reached by the red mud in 48 hours.

  17. Removing 3,5-Dichlorophenol from Wastewater by Alternative Adsorbents

    Kobetičová Hana

    2014-12-01

    Full Text Available The main objective of this paper is to evaluate an efficiency of 3,5 - dichlorophenol removal from wastewater by using alternative adsorbents. Chlorophenols are organic compounds consisting of a benzene ring, OH groups and also atoms of chlorine. Chlorophenols may have a huge isomere variety that means there are differences in their chemical and physical properties. Due to their toxicity it is necessary to remove them from waste water and in this paper an alternative way of such process is described.

  18. 3,5-Dichlorophenol Removal From Wastewater Using Alternative Adsorbents

    Kobetičová, Hana; Lipovský, Marek; Wachter, Igor; Soldán, Maroš

    2015-06-01

    The main objective of this paper is to evaluate the efficiency of 3,5-dichlorophenol removal from wastewater by using alternative low cost adsorbents. Waste from the production and processing of metals (black nickel mud, red mud) and a biosorbent (Lemna minor) were used for this research. Initial concentration of the contaminant was 4 mmol L-1, the contact time of sorbent and waste water was 0 - 48 hrs and the temperature during experiment was 25 ± 0.2 °C. The results show that the highest removal efficiency of 3,5 - dichlorophenol (58.18 %) was reached by the red mud in 48 hours.

  19. Behavior of adsorbed Poly-A onto sodium montmorillonite

    Palomino-Aquino, Nayeli [Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (Mexico); Negrón-Mendoza, Alicia, E-mail: negron@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (Mexico)

    2015-07-23

    The adsorption of Poly-A (a polynucleotide consisting of adenine, ribose and a phosphate group), onto a clay mineral, was studied to investigate the extent of adsorption, the site of binding, and the capacity of the clay to protect Poly-A, while it is adsorbed onto the clay, from external sources of energy. The results showed that Poly-A presented a high percentage of adsorption at the edges of the clay and that the survival of the polynucleotide was superior to irradiating the polymer in the absence of the clay.

  20. Detection of adsorbed water and hydroxyl on the moon

    Clark, R.N.

    2009-01-01

    Data from the Visual and Infrared Mapping Spectrometer (VIAAS) on Cassini during its flyby of the AAoon in 1999 show a broad absorption at 3 micrometers due to adsorbed water and near 2.8 micrometers attributed to hydroxyl in the sunlit surface on the AAoon. The amounts of water indicated in the spectra depend on the type of mixing and the grain sizes in the rocks and soils but could be 10 to 1000 parts per million and locally higher. Water in the polar regions may be water that has migrated to the colder environments there. Trace hydroxyl is observed in the anorthositic highlands at lower latitudes.