WorldWideScience

Sample records for 22f adsorption step

  1. Adsorption-induced step formation

    DEFF Research Database (Denmark)

    Thostrup, P.; Christoffersen, Ebbe; Lorensen, Henrik Qvist;

    2001-01-01

    Through an interplay between density functional calculations, Monte Carlo simulations and scanning tunneling microscopy experiments, we show that an intermediate coverage of CO on the Pt(110) surface gives rise to a new rough equilibrium structure with more than 50% step atoms. CO is shown to bind...... so strongly to low-coordinated Pt atoms that it can break Pt-Pt bonds and spontaneously form steps on the surface. It is argued that adsorption-induced step formation may be a general effect, in particular at high gas pressures and temperatures....

  2. Adsorption and diffusion of Si adatom near single-layer steps on Si surface

    Institute of Scientific and Technical Information of China (English)

    Zhu Xiao-Yan; Huang Yan

    2005-01-01

    By use of the empirical tight-binding (ETB) method, the adsorption and diffusion behaviours of single silicon adatom on the reconstructed Si(100) surface with single-layer steps are simulated. The adsorption energies around the SA step, nonrebonded SB step, rebonded SB step, and rough SB step with a kink structure are specially mapped out in this paper, from which the favourable binding sites and several possible diffusion paths are achieved. Because of the rebonded and kink structures, the SB step is more suitable for the attachment of Si adatom than the SA step or defective surface.

  3. One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Larsen, Niels Bent

    2013-01-01

    The non-specific adsorption of dissolved analytes strongly reduces the sensitivity and reliability in polymer microanalytical systems. Here, a one-step aqueous phase procedure modifies polymer material surfaces to strongly reduce their non-specific adsorption of a broad range of organic analytes ...... systems, including polystyrene (PS), cyclic olefin copolymer (COC), liquid crystalline polymer (LCP), and polyimide (PI)....

  4. Ethylene adsorption on regularly stepped copper surface: C 2H 4 on Cu(210)

    Science.gov (United States)

    Yamazaki, Daichi; Okada, Michio; Franco, Francisco C., Jr.; Kasai, Toshio

    2011-05-01

    Ethylene adsorption on regularly stepped Cu(210) surface was investigated with infrared reflection-adsorption spectroscopy and temperature programmed desorption. At 90 K, π-bonded ethylene was adsorbed on Cu(210) molecularly and all species were desorbed below 160 K. There were three types of π-bonded ethylene on the surface. Recent experimental studies have suggested that ethylene is dehydrogenated on Cu(410) due to the regular step [Kravchuk et al ., J. Phys. Chem. C, 113 (2009) 20881]. However, neither the formation of di-σ-bonded ethylene nor dehydrogenation occurred on Cu(210).

  5. One-step polymer surface modification for minimizing drug, protein, and DNA adsorption in microanalytical systems.

    Science.gov (United States)

    Larsen, Esben Kjær Unmack; Larsen, Niels B

    2013-02-21

    The non-specific adsorption of dissolved analytes strongly reduces the sensitivity and reliability in polymer microanalytical systems. Here, a one-step aqueous phase procedure modifies polymer material surfaces to strongly reduce their non-specific adsorption of a broad range of organic analytes including hydrophobic and hydrophilic drugs (0.23 8) in their pharmaceutically relevant concentration range ≤100 nM. The low adsorption is mediated by photochemical conjugation, where polyethylene glycol (PEG) polymers in aqueous solution are covalently bound to the surface by UV illumination of dissolved benzophenone and a functionalized PEG. The method can coat the interior of polymer systems made from a range of materials commonly used in microanalytical systems, including polystyrene (PS), cyclic olefin copolymer (COC), liquid crystalline polymer (LCP), and polyimide (PI). PMID:23254780

  6. Adsorption and Diffusion of O Atoms on Ag(210) Stepped Surface

    Institute of Scientific and Technical Information of China (English)

    DIAO Zhao-yu; ZHANG Xue-na; WANG Ze-xin; ZHANG Jing

    2007-01-01

    The O-Ag(210) surface adsorption system was studied via the five-parameter Morse potential theory. Meanwhile, the 2O-Ag(210) system was investigated via the extended London-Eyring-Polanyi-Sato(LEPS) potential theory to learn the interaction between the adsorption states. Calculated results demonstrate that there are two stable onsurface adsorption sites(B and H) for O atoms on Ag(210) stepped surface. And the perpendicular vibrations are 30.3 and 42. 9 meV, which are close to that observed in high resolution electron energy loss spectroscopy(HREELS). Also, there exists an octahedral subsurface adsorption state with a high vibrational frequency, and the interaction between the on-surface and subsurface O species is slight. The mode at 54. 6 meV, which is close to that observed in HREELS(54-56 meV), is because of the vibration of the O atom on B site under the influence of that on H site.

  7. Some problems in adsorption and calorimetric studies of the steps of catalytic processes

    Institute of Scientific and Technical Information of China (English)

    Victor E. Ostrovskii

    2004-01-01

    Principal side factors as well as technical and procedural peculiarities capable of distorting the results of measurements of adsorbed and desorbed amounts, of falsifying the nature of the processes proceeding in the systems under study, and of promoting artifacts in calorimetric and other studies of gas chemisorption on powders are considered. Modified techniques and procedures allowing the elimination of sources of side phenomena and artifacts and freeing traditional glass static adsorption apparatuses and experimental procedures from undesirable factors and peculiarities are proposed.Some available chemisorption and calorimetric data representing artifacts and also some data that are not artifacts but,due to imperfections of chemisorption techniques, show up as artifacts are presented and discussed. Several applications of the improved techniques and procedures to calorimetric and adsorption studies of the steps of catalytic processes proceeding on the basis of natural gas and of products of its processing are presented and discussed.

  8. nanoparticles via a facile one-step solvothermal process for adsorption of bovine serum albumin

    Science.gov (United States)

    Shen, Mao; Yu, Yujing; Fan, Guodong; Chen, Guang; Jin, Ying min; Tang, Wenyuan; Jia, Wenping

    2014-06-01

    Preparation of magnetic nanoparticles coated with chitosan (CS-coated Fe3O4 NPs) in one step by the solvothermal method in the presence of different amounts of added chitosan is reported here. The magnetic property of the obtained magnetic composite nanoparticles was confirmed by X-ray diffraction (XRD) and magnetic measurements (VSM). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allowed the identification of spherical nanoparticles with about 150 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy (FTIR) demonstrated that CS-coated Fe3O4 NPs were obtained. Chitosan content in the obtained nanocomposites was estimated by thermogravimetric analysis (TGA). The adsorption properties of the CS-coated Fe3O4 NPs for bovine serum albumin (BSA) were investigated under different concentrations of BSA. Compared with naked Fe3O4 nanoparticles, the CS-coated Fe3O4 NPs showed a higher BSA adsorption capacity (96.5 mg/g) and a fast adsorption rate (45 min) in aqueous solutions. This work demonstrates that the prepared magnetic nanoparticles have promising applications in enzyme and protein immobilization.

  9. Oxygen Atom Adsorption and Diffusion on Pd Low-index Surfaces and (311) Stepped Surface

    Institute of Scientific and Technical Information of China (English)

    WANG, Ze-Xin(王泽新); JIA, Xiang-Feng(贾祥凤); TIAN, Feng-Hui(田凤惠); CHEN, Shou-Gang(陈守刚)

    2004-01-01

    The 5-parameter Morse potential (5-MP for short) of the interaction system between an oxygen atom and palladium surface clusters was constructed. The adsorption and diffusion of an oxygen atom on low index surfaces Pd (100), Pd (111), Pd (110) and Pd (311) stepped surface were investigated in detail with 5-MP. It is found that fcc and hcp sites on the (111) surface and (111) microfacets are equivalent. The calculation results show that O atom adsorbs in the three-fold hollow site, and the long-bridge site is a stable site both in regular Pd (110) surface and in the (1×2) missing-row reconstruction structure. Moreover, in the study of O-Pd (311) surface system, We conclude that there are two stable adsorption states (four-fold site: H4, three-fold site: Hh) on O-Pd (311) surface and the three-fold site (Hf) is the metastable adsorption. At low coverage oxygen atom favors the four-fold hollow site (H4).

  10. Thermodynamic properties of hydrogen-water adsorption at terraces and steps of Pt(111) vicinal surface electrodes

    Science.gov (United States)

    Gómez-Marín, Ana M.; Feliu, Juan M.

    2016-04-01

    In this work, the effect of temperature on the adsorption states of Pt(111) vicinal surface electrodes in perchloric acid is studied through a thermodynamic analysis. The method allows calculating thermodynamic properties of the interface. In this framework, the concept of the generalized isotherm and the statistical thermodynamics description are applied to calculate formal entropies, enthalpies and Gibbs energies, ΔGbari0, of the adsorption processes at two-dimensional terraces and one-dimensional steps. These values are compared with data from literature. Additionally, the effect of the step density on ΔGbari0 and on the lateral interactions between adsorbed species, ωij, at terraces and steps is also determined. Calculated ΔGbari0, entropies and enthalpies are almost temperature-independent, especially at steps, but they depend on the step orientation. In contrast, ΔGbari0 and ωij at terraces depend on the step density, following a linear tendency for terrace lengths larger than 5 atoms. However, while ΔGbari0 increases with the step density, ωij decreases. Results were explained by considering the modification in the energetic surface balance by hydrogen, Hads, and water, H2Oads, co-adsorption on the electrode, which in turn determines the whole adsorption processes on terraces and steps.

  11. Elementary Steps of Syngas Reactions on Mo2C(001): Adsorption Thermochemistry and Bond Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Medford, Andrew

    2012-02-16

    Density functional theory (DFT) and ab initio thermodynamics are applied in order to investigate the most stable surface and subsurface terminations of Mo{sub 2}C(001) as a function of chemical potential and in the presence of syngas. The Mo-terminated (001) surface is then used as a model surface to evaluate the thermochemistry and energetic barriers for key elementary steps in syngas reactions. Adsorption energy scaling relations and Broensted-Evans-Polanyi relationships are established and used to place Mo{sub 2}C into the context of transition metal surfaces. The results indicate that the surface termination is a complex function of reaction conditions and kinetics. It is predicted that the surface will be covered by either C{sub 2}H{sub 2} or O depending on conditions. Comparisons to transition metals indicate that the Mo-terminated Mo{sub 2}C(001) surface exhibits carbon reactivity similar to transition metals such as Ru and Ir, but is significantly more reactive towards oxygen.

  12. Repulsive interactions induced by specific adsorption: Anomalous step diffusivity and inadequacy of nearest-neighbor Ising model. (part I experimental)

    Science.gov (United States)

    Al-Shakran, Mohammad; Kibler, Ludwig A.; Jacob, Timo; Ibach, Harald; Beltramo, Guillermo L.; Giesen, Margret

    2016-09-01

    This is Part I of two closely related papers, where we show that the specific adsorption of anions leads to a failure of the nearest-neighbor Ising model to describe island perimeter curvatures on Au(100) electrodes in dilute KBr, HCl and H2SO4 electrolytes and the therewith derived step diffusivity vs. step orientation. This result has major consequences for theoretical studies aiming at the understanding of growth, diffusion and degradation phenomena. Part I focuses on the experimental data. As shown theoretically in detail in Part II (doi:10.1016/j.susc.2016.03.022), a set of nearest-neighbor and next-nearest-neighbor interaction energies (ɛNN, ɛNNN) can uniquely be derived from the diffusivity of steps along and . We find strong repulsive next-nearest neighbor (NNN) interaction in KBr and HCl, whereas NNN interaction is negligibly for H2SO4. The NNN repulsive interaction energy ɛNNN therefore correlates positively with the Gibbs adsorption energy of the anions. We find furthermore that ɛNNN increases with increasing Br- and Cl- coverage. The results for ɛNN and ɛNNN are quantitatively consistent with the coverage dependence of the step line tension. We thereby establish a sound experimental base for theoretical studies on the energetics of steps in the presence of specific adsorption.

  13. Determination of the mass transfer limiting step of dye adsorption onto commercial adsorbent by using mathematical models.

    Science.gov (United States)

    Marin, Pricila; Borba, Carlos Eduardo; Módenes, Aparecido Nivaldo; Espinoza-Quiñones, Fernando R; de Oliveira, Silvia Priscila Dias; Kroumov, Alexander Dimitrov

    2014-01-01

    Reactive blue 5G dye removal in a fixed-bed column packed with Dowex Optipore SD-2 adsorbent was modelled. Three mathematical models were tested in order to determine the limiting step of the mass transfer of the dye adsorption process onto the adsorbent. The mass transfer resistance was considered to be a criterion for the determination of the difference between models. The models contained information about the external, internal, or surface adsorption limiting step. In the model development procedure, two hypotheses were applied to describe the internal mass transfer resistance. First, the mass transfer coefficient constant was considered. Second, the mass transfer coefficient was considered as a function of the dye concentration in the adsorbent. The experimental breakthrough curves were obtained for different particle diameters of the adsorbent, flow rates, and feed dye concentrations in order to evaluate the predictive power of the models. The values of the mass transfer parameters of the mathematical models were estimated by using the downhill simplex optimization method. The results showed that the model that considered internal resistance with a variable mass transfer coefficient was more flexible than the other ones and this model described the dynamics of the adsorption process of the dye in the fixed-bed column better. Hence, this model can be used for optimization and column design purposes for the investigated systems and similar ones.

  14. Elementary Steps and Site Requirements for NOx Adsorption and Oxidation on Metal and Oxide Surfaces

    OpenAIRE

    Weiss, Brian M.

    2010-01-01

    NO oxidation catalysts are used in conjunction with NOx adsorbents to remove toxic nitrogen oxides from combustion effluents that lack CO and residual hydrocarbons as reductants. Efficient NOx trapping strategies require detailed knowledge of the reaction mechanism and the structural requirements for NO oxidation and for NOx adsorption, which are investigated here by kinetic, isotopic, and spectroscopic methods. NO oxidation rates on Pt, PdO, RhO2, and Co3O4 catalysts increase linearly with O...

  15. Molecular N-2 chemisorption-specific adsorption on step defect sites on Pt surfaces

    OpenAIRE

    Tripa, C. Emil; Zubkov, T.S.; Yates, John T.; Mavrikakis, Manos; Nørskov, Jens Kehlet

    1999-01-01

    Infrared reflection-absorption spectroscopy and density functional theory, within the generalized gradient approximation, were used to investigate both experimentally and theoretically N-2 chemisorption on stepped and smooth Pt surfaces. N-2 chemisorption was observed to occur only on the edge atoms of step defect sites in atop configuration by both methods. The calculated vibrational frequency of N-2 chemisorbed on Pt(112) step sites (2244 cm(-1)) is in good agreement with the frequency obse...

  16. A DFT study of water adsorption on rutile TiO2 (110) surface: The effects of surface steps.

    Science.gov (United States)

    Zheng, Ting; Wu, Chunya; Chen, Mingjun; Zhang, Yu; Cummings, Peter T

    2016-07-28

    The associative and dissociative adsorption of water molecules at low-coverage situations on rutile TiO2 (110) surface with step defects was investigated by the density functional theory calculations. Structural optimization of the hydroxylated/hydrated configurations at step edges along the 11̄1 crystal directions and the dynamic process of water dissociation were discussed to get a better description of the water/TiO2 interface. Our results indicate that steps on the TiO2 (110) surface could be an active site for water dissociation. The results of geometry optimization suggest that the stability of hydroxylated configuration is largely dependent on the locations of the H species and the recombination of water molecules from hydroxyls is observed in the fully hydroxylated condition. However, these hydroxyls can be stabilized by the associatively absorbed water nearby by forming competitive intermolecular hydrogen bonds. The dynamics of water dissociation and hydrogen diffusion were studied by the first principles molecular dynamics simulation and our results suggest that the hydrogen released by water dissociation can be transferred among the adsorbates, such as the unsaturated oxygen atoms-H2O-hydroxyl (TiO-H2O-OH) complex at step edges, or gradually diffuses to the bulk water system in the form of hydronium (H3O(+)) at higher water coverage. PMID:27475381

  17. A DFT study of water adsorption on rutile TiO2 (110) surface: The effects of surface steps

    Science.gov (United States)

    Zheng, Ting; Wu, Chunya; Chen, Mingjun; Zhang, Yu; Cummings, Peter T.

    2016-07-01

    The associative and dissociative adsorption of water molecules at low-coverage situations on rutile TiO2 (110) surface with step defects was investigated by the density functional theory calculations. Structural optimization of the hydroxylated/hydrated configurations at step edges along the crystal directions and the dynamic process of water dissociation were discussed to get a better description of the water/TiO2 interface. Our results indicate that steps on the TiO2 (110) surface could be an active site for water dissociation. The results of geometry optimization suggest that the stability of hydroxylated configuration is largely dependent on the locations of the H species and the recombination of water molecules from hydroxyls is observed in the fully hydroxylated condition. However, these hydroxyls can be stabilized by the associatively absorbed water nearby by forming competitive intermolecular hydrogen bonds. The dynamics of water dissociation and hydrogen diffusion were studied by the first principles molecular dynamics simulation and our results suggest that the hydrogen released by water dissociation can be transferred among the adsorbates, such as the unsaturated oxygen atoms-H2O-hydroxyl (TiO-H2O-OH) complex at step edges, or gradually diffuses to the bulk water system in the form of hydronium (H3O+) at higher water coverage.

  18. Boron nitride ultrathin fibrous nanonets: one-step synthesis and applications for ultrafast adsorption for water treatment and selective filtration of nanoparticles.

    Science.gov (United States)

    Lian, Gang; Zhang, Xiao; Si, Haibin; Wang, Jun; Cui, Deliang; Wang, Qilong

    2013-12-26

    Novel boron nitride (BN) ultrathin fibrous networks are firstly synthesized via an one-step solvothermal process. The average diameter of BN nanofibers is only ~8 nm. This nanonets exhibit excellent performance for water treatment. The maximum adsorption capacity for methyl blue is 327.8 mg g(-1). Especially, they present the property of ultrafast adsorption for dye removal. Only ~1 min is enough to almost achieve the adsorption equilibrium. In addition, the BN fibrous nanonets could be applied for the size-selective separation of nanoparticles via a filtration process.

  19. Two-step adsorption on jungle-gym-type porous coordination polymers: dependence on hydrogen-bonding capability of adsorbates, ligand-substituent effect, and temperature.

    Science.gov (United States)

    Uemura, Kazuhiro; Yamasaki, Yukari; Onishi, Fumiaki; Kita, Hidetoshi; Ebihara, Masahiro

    2010-11-01

    A preliminary study of isopropanol (IPA) adsorption/desorption isotherms on a jungle-gym-type porous coordination polymer, [Zn(2)(bdc)(2)(dabco)](n) (1, H(2)bdc = 1,4-benzenedicarboxylic acid, dabco =1,4-diazabicyclo[2.2.2]octane), showed unambiguous two-step profiles via a highly shrunk intermediate framework. The results of adsorption measurements on 1, using probing gas molecules of alcohol (MeOH and EtOH) for the size effect and Me(2)CO for the influence of hydrogen bonding, show that alcohol adsorption isotherms are gradual two-step profiles, whereas the Me(2)CO isotherm is a typical type-I isotherm, indicating that a two-step adsorption/desorption is involved with hydrogen bonds. To further clarify these characteristic adsorption/desorption behaviors, selecting nitroterephthalate (bdc-NO(2)), bromoterephthalate (bdc-Br), and 2,5-dichloroterephthalate (bdc-Cl(2)) as substituted dicarboxylate ligands, isomorphous jungle-gym-type porous coordination polymers, {[Zn(2)(bdc-NO(2))(2)(dabco)]·solvents}(n) (2 ⊃ solvents), {[Zn(2)(bdc-Br)(2)(dabco)]·solvents}(n) (3 ⊃ solvents), and {[Zn(2)(bdc-Cl(2))(2)(dabco)]·solvents}(n) (4 ⊃ solvents), were synthesized and characterized by single-crystal X-ray analyses. Thermal gravimetry, X-ray powder diffraction, and N(2) adsorption at 77 K measurements reveal that [Zn(2)(bdc-NO(2))(2)(dabco)](n) (2), [Zn(2)(bdc-Br)(2)(dabco)](n) (3), and [Zn(2)(bdc-Cl(2))(2)(dabco)](n) (4) maintain their frameworks without guest molecules with Brunauer-Emmett-Teller (BET) surface areas of 1568 (2), 1292 (3), and 1216 (4) m(2) g(-1). As found in results of MeOH, EtOH, IPA, and Me(2)CO adsorption/desorption on 2-4, only MeOH adsorption on 2 shows an obvious two-step profile. Considering the substituent effects and adsorbate sizes, the hydrogen bonds, which are triggers for two-step adsorption, are formed between adsorbates and carboxylate groups at the corners in the pores, inducing wide pores to become narrow pores. Interestingly, such

  20. Pyridine on flat Pt(111) and stepped Pt(355)—An in situ HRXPS investigation of adsorption and thermal evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wöckel, Claudia; Eilert, Andrè; Welke, Martin; Schöppke, Matthias; Denecke, Reinhard, E-mail: denecke@uni-leipzig.de [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany); Steinrück, Hans-Peter [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen (Germany)

    2016-01-07

    We investigated the adsorption and reaction of pyridine on flat Pt(111) and stepped Pt(355) surfaces via high-resolution in situ x-ray photoelectron spectroscopy. The surfaces were exposed to pyridine at temperatures between 112 and 300 K while simultaneously recording XP spectra. Subsequently, the crystals were annealed and the temperature dependencies of the N 1s and C 1s core levels were studied again in a continuous and quantitative way. Various surface species were found, namely, physisorbed, flat-lying and end-on pyridine, α-pyridyl species on the terraces and on the steps and several unidentified high temperature species. We were able to show an influence of the steps of Pt(355) by pre-adsorbing silver next to the step, which selectively suppresses the step adsorption.

  1. 75 FR 340 - Approval for Expansion of Subzone 22F, Abbott Molecular, Inc. (Pharmaceutical and Molecular...

    Science.gov (United States)

    2010-01-05

    ...- 17-09); Whereas, notice inviting public comment has been given in the Federal Register (74 FR 8052... Foreign-Trade Zones Board Approval for Expansion of Subzone 22F, Abbott Molecular, Inc. (Pharmaceutical and Molecular Diagnostic Products), Chicago, IL, Area Pursuant to its authority under the...

  2. Effects of extra-cellular polymeric substances on organic pollutants biodegradation kinetics for A-step of adsorption-biodegradation process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The features of organic pollutants degradation mainly characterized by bio-flocculation for step-A of adsorption-biodegredation(AB) process were studied. By investigating the relationship of extracellular polymeric substances(EPS) with bioflocculation and introducing kinetic model of organic pollutant degradation into EPS, the kinetic model of organic pollutant degradation for step-A bioflocculation was deducted. And through the experiments,the kinetic constants were calculated as follows: k1 =0. 005 3; kc1 =1710.7 and vmax1=10 min-1.

  3. A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

    Science.gov (United States)

    Li, Wenting; Shang, Chunli; Li, Xue

    2015-12-01

    Anatase TiO2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption analysis, UV-vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO2 NSs possess high surface area up to 378 m2 g-1. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

  4. Preferential adsorption of C60 molecules to step edges of the Si(110)-16 × 2 single domain surface

    International Nuclear Information System (INIS)

    The Si(110) surface has a quite unique one-dimensional (1-D) stable structure with 16 × 2 reconstruction. Since the perfectly straight rows extend over micrometers, the 16 × 2 structure can be a superior template for 1-D nanostructures. However, controlled nanostructures using the Si(110)-16 × 2 template has not been fabricated yet. In this study, we have investigated the adsorption of C60 molecules on the Si(110)-16 × 2 surface at various surface temperatures, and found that the C60 preferable adsorption sites are substantially changed, depending on the surface temperature. The obtained results indicate that the organic 1-D nanostructure can be fabricated on the Si(110)-16 × 2 surface by controlling the surface temperature.

  5. The synthesis and characterization of monodispersed chitosan-coated Fe3O4 nanoparticles via a facile one-step solvothermal process for adsorption of bovine serum albumin.

    Science.gov (United States)

    Shen, Mao; Yu, Yujing; Fan, Guodong; Chen, Guang; Jin, Ying Min; Tang, Wenyuan; Jia, Wenping

    2014-01-01

    Preparation of magnetic nanoparticles coated with chitosan (CS-coated Fe3O4 NPs) in one step by the solvothermal method in the presence of different amounts of added chitosan is reported here. The magnetic property of the obtained magnetic composite nanoparticles was confirmed by X-ray diffraction (XRD) and magnetic measurements (VSM). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allowed the identification of spherical nanoparticles with about 150 nm in average diameter. Characterization of the products by Fourier transform infrared spectroscopy (FTIR) demonstrated that CS-coated Fe3O4 NPs were obtained. Chitosan content in the obtained nanocomposites was estimated by thermogravimetric analysis (TGA). The adsorption properties of the CS-coated Fe3O4 NPs for bovine serum albumin (BSA) were investigated under different concentrations of BSA. Compared with naked Fe3O4 nanoparticles, the CS-coated Fe3O4 NPs showed a higher BSA adsorption capacity (96.5 mg/g) and a fast adsorption rate (45 min) in aqueous solutions. This work demonstrates that the prepared magnetic nanoparticles have promising applications in enzyme and protein immobilization. PMID:24994954

  6. Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: Characterizing two-step adsorption and partition processes through experimental and modeling approaches

    International Nuclear Information System (INIS)

    Highlights: • The sorption of cationic gemini surfactant at the soil/water interface was studied. • A two-step adsorption and partition model was developed. • The developed model could better simulate the sorption of ionic surfactant on soil. • Binary gemini surfactant mixtures substantially enhanced the soil retention for PHE. • The sorption of cationic gemini was inhibited by the increasing nonionic surfactant. - Abstract: The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C12E10) was investigated. The maximum apparent sorption coefficient Kd* reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C12E10 surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C12E10 (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C12E10 dose; and a higher initial 12-2-12 gemini dose showed a higher “desorption” rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308 K

  7. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    Science.gov (United States)

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  8. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    Science.gov (United States)

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  9. Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: Characterizing two-step adsorption and partition processes through experimental and modeling approaches

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shan [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Huang, Gordon, E-mail: gordon.huang@uregina.ca [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); An, Chunjiang [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Wei, Jia [Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124 (China); Yao, Yao [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada)

    2015-04-09

    Highlights: • The sorption of cationic gemini surfactant at the soil/water interface was studied. • A two-step adsorption and partition model was developed. • The developed model could better simulate the sorption of ionic surfactant on soil. • Binary gemini surfactant mixtures substantially enhanced the soil retention for PHE. • The sorption of cationic gemini was inhibited by the increasing nonionic surfactant. - Abstract: The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C{sub 12}E{sub 10}) was investigated. The maximum apparent sorption coefficient K{sub d}{sup *} reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C{sub 12}E{sub 10} surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C{sub 12}E{sub 10} (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C{sub 12}E{sub 10} dose; and a higher initial 12-2-12 gemini dose showed a higher “desorption” rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308 K.

  10. Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: characterizing two-step adsorption and partition processes through experimental and modeling approaches.

    Science.gov (United States)

    Zhao, Shan; Huang, Gordon; An, Chunjiang; Wei, Jia; Yao, Yao

    2015-04-01

    The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C12E10) was investigated. The maximum apparent sorption coefficient Kd(*) reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C12E10 surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C12E10 (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C12E10 dose; and a higher initial 12-2-12 gemini dose showed a higher "desorption" rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308K. PMID:25576782

  11. Kinetic modelling of enzyme inactivation Kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F.

    NARCIS (Netherlands)

    Schokker, E.P.

    1997-01-01

    The kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F was studied. It was established, by making use of kinetic modelling, that heat inactivation in the temperature range 35 - 70 °C was most likely caused by intermolecular autoproteolysis, where unfolded

  12. Structure sensitivity in adsorption

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Nielsen, Ole Holm; Nørskov, Jens Kehlet

    1997-01-01

    The structure sensitivity of CO adsorption on different flat, stepped, kinked and reconstructed Pt surfaces is studied using large-scale density-functional calculations. We find an extremely strong structure sensitivity in the adsorption energy with variations up to 1 eV (or 100%) from one...

  13. A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

    KAUST Repository

    Wang, Yu

    2015-01-01

    © The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m2 g-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g-1).

  14. Invasive Streptococcus pneumoniae in Canada, 2011-2014: Characterization of new candidate 15-valent pneumococcal conjugate vaccine serotypes 22F and 33F.

    Science.gov (United States)

    Golden, Alyssa R; Adam, Heather J; Zhanel, George G

    2016-05-17

    Emerging non-PCV-13 Streptococcus pneumoniae serotypes 22F and 33F are included in a new 15-valent pneumococcal conjugate vaccine currently undergoing clinical trials in the United States. This study assessed the antimicrobial resistance and genetic relatedness of these two emerging pneumococcal serotypes. Of the 5075 invasive pneumococcal isolates collected in Canada from 2011 to 2014, 9.8% (497/5075) were serotype 22F and 3.2% (160/5075) were serotype 33F. Despite being among the top 4 most common serotypes collected each study year, serotype 22F demonstrated ≥98% susceptibility to all antimicrobials tested except clarithromycin and few were multi-drug resistant (MDR) (0.8%, 4/497). Serotype 22F isolates were highly clonal (ST433), with two isolates showing high relatedness to MDR international clone Sweden(15A)-25 (ST63). Conversely, serotype 33F showed greater antimicrobial resistance, greater genetic diversity and a higher proportion of MDR isolates (8.8%, 14/160). The prevalence of serotype 33F increased significantly during 2011-2014 (p=0.005). PMID:27085174

  15. The synthesis and characterization of monodispersed chitosan-coated Fe3O4 nanoparticles via a facile one-step solvothermal process for adsorption of bovine serum albumin

    OpenAIRE

    Shen, Mao; Yu, Yujing; Fan, Guodong; Chen, Guang; Jin, Ying min; Tang, Wenyuan; Jia, Wenping

    2014-01-01

    Preparation of magnetic nanoparticles coated with chitosan (CS-coated Fe3O4 NPs) in one step by the solvothermal method in the presence of different amounts of added chitosan is reported here. The magnetic property of the obtained magnetic composite nanoparticles was confirmed by X-ray diffraction (XRD) and magnetic measurements (VSM). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) allowed the identification of spherical nanoparticles with about 150 nm in averag...

  16. Population structure and drug resistance patterns of emerging non-PCV-13 Streptococcus pneumoniae serotypes 22F, 15A, and 8 isolated from adults in Ontario, Canada.

    Science.gov (United States)

    Duvvuri, Venkata R; Deng, Xianding; Teatero, Sarah; Memari, Nader; Athey, Taryn; Fittipaldi, Nahuel; Gubbay, Jonathan B

    2016-08-01

    The introduction of pneumococcal conjugate vaccines has led to the emergence of non-vaccine serotypes, which contributed to invasive pneumococcal disease in Canada and worldwide. A significant increase in the prevalence of non-13-valent pneumococcal conjugate vaccine (PCV-13)-included serotypes 22F, 15A, and 8 was observed from 2009 to 2013 in Ontario (all p valuesStreptococcus pneumoniae population structures and dynamics, and its utility in molecular surveillance. PMID:27071529

  17. Two-step Resin Adsorption for Purification of Stevia Glycosides from Stevia Rebaudiana Aqueous Extract%两步树脂法从甜叶菊水提液中纯化甜菊糖苷

    Institute of Scientific and Technical Information of China (English)

    唐乐乐; 叶发银; 杨瑞金; 华霄; 赵伟; 张文斌

    2012-01-01

    采用两步树脂法从甜叶菊水提液中提取纯化甜菊糖苷。第一步主要是脱色,通过比较大孔树脂D293、D296、JN-1、JN-2、D890和D201处理甜叶菊水提液的脱色率、甜菊糖苷保留率和解吸性能,发现JN-1的效果最好。在优化条件下,甜叶菊水提液经JN-1处理,甜菊糖苷纯度由原来的42.65%提高到67.33%,收率达到84.87%;第二步的主要目的是提高产品纯度,通过比较大孔树脂AB-8、JNF-1、X-5、NKA-II和D101对甜菊糖苷的吸附-解吸性能和得到的纯化液的甜菊糖苷纯度,发现JNF-1的效果最好。在优化的条件下,JN-1处理后的甜菊糖苷溶液进一步采用JNF-1吸附,溶液的甜菊糖苷纯度提高至92.92%,收率91.08%。%A new method for purification of steviol glycosides from Stevia Rebaudiana crude extracts by macro- porous adsorption resin (MAR) was systematically investigated. The purification procedure consisted of two steps. In the first step, the main purpose was decolorization, and several types of macroporous resins including D293, D296, JN-1, JN-2, D890 and D201 were used in order to choose the best resin. JN-1 resin was selected according to their decolorization ratio, the retention of steviol glycosides ratio and desorption ratio. In order to increase the purity, a sec- ond step of refining was added by screening various types of macroporous resins (AB-8, JNF-1, X-5, NKA-II and D101). The results demonstrated that JNF-1 resin was the most suitable resin. The purity of steviol glycosides after the first step JN-1 was from 42.65% to 67.33% with a recovery of 84.87%. The purity of steviol glycosides in- creased to 92.92% with a recovery of 91.08% after the second step JNF-1.

  18. Next Step for STEP

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Claire [CTSI; Bremner, Brenda [CTSI

    2013-08-09

    The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.

  19. Thermodynamics of binary gas adsorption in nanopores.

    Science.gov (United States)

    Dutta, Sujeet; Lefort, Ronan; Morineau, Denis; Mhanna, Ramona; Merdrignac-Conanec, Odile; Saint-Jalmes, Arnaud; Leclercq, Théo

    2016-09-21

    MCM-41 nanoporous silicas show a very high selectivity for monoalcohols over aprotic molecules during adsorption of a binary mixture in the gas phase. We present here an original use of gravimetric vapour sorption isotherms to characterize the role played by the alcohol hydrogen-bonding network in the adsorption process. Beyond simple selectivity, vapour sorption isotherms measured for various compositions help to completely unravel at the molecular level the step by step adsorption mechanism of the binary system in the nanoporous solid, from the first monolayers to the complete liquid condensation. PMID:27532892

  20. ADSORPTION AND RELEASING PROPERTIES OF BEAD CELLULOSE

    Institute of Scientific and Technical Information of China (English)

    A. Morales; E. Bordallo; V. Leon; J. Rieumont

    2004-01-01

    The adsorption of some dyes on samples of bead cellulose obtained in the Unit of Research-Production "Cuba 9"was studied. Methylene blue, alizarin red and congo red fitted the adsorption isotherm of Langmuir. Adsorption kinetics at pH = 6 was linear with the square root of time indicating the diffusion is the controlling step. At pH = 12 a non-Fickian trend was observed and adsorption was higher for the first two dyes. Experiments carried out to release the methylene blue occluded in the cellulose beads gave a kinetic behavior of zero order. The study of cytochrome C adsorption was included to test a proteinic material. Crosslinking of bead cellulose was performed with epichlorohydrin decreasing its adsorption capacity in acidic or alkaline solution.

  1. Adsorption Rate Models for Multicomponent Adsorption Systems

    Institute of Scientific and Technical Information of China (English)

    姚春才

    2004-01-01

    Three adsorption rate models are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models I and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model I is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption processes while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.

  2. Adsorption and wetting.

    NARCIS (Netherlands)

    Schlangen, L.J.M.

    1995-01-01

    Adsorption and wetting are related phenomena. In order to improve knowledge of both and their relations, experiments, thermodynamics and a theoretical interpretation have been connected, starring n-alkanes.Starting from the Gibbs adsorption equation thermodynamic relations between vapour adsorption

  3. Host receptors for bacteriophage adsorption.

    Science.gov (United States)

    Bertozzi Silva, Juliano; Storms, Zachary; Sauvageau, Dominic

    2016-02-01

    The adsorption of bacteriophages (phages) onto host cells is, in all but a few rare cases, a sine qua non condition for the onset of the infection process. Understanding the mechanisms involved and the factors affecting it is, thus, crucial for the investigation of host-phage interactions. This review provides a survey of the phage host receptors involved in recognition and adsorption and their interactions during attachment. Comprehension of the whole infection process, starting with the adsorption step, can enable and accelerate our understanding of phage ecology and the development of phage-based technologies. To assist in this effort, we have established an open-access resource--the Phage Receptor Database (PhReD)--to serve as a repository for information on known and newly identified phage receptors. PMID:26755501

  4. Role of steps in N-2 activation on Ru(0001)

    DEFF Research Database (Denmark)

    Dahl, Søren; Logadottir, Ashildur; Egeberg, Rasmus;

    1999-01-01

    Using adsorption experiments and density functional calculations we show that N-2 dissociation on the Ru(0001) surface is totally dominated by steps. The measured adsorption rate at the steps is at least 9 orders of magnitude higher than on the terraces at 500 K, and the corresponding calculated ...

  5. Adsorption and wetting.

    OpenAIRE

    Schlangen, L.J.M.

    1995-01-01

    Adsorption and wetting are related phenomena. In order to improve knowledge of both and their relations, experiments, thermodynamics and a theoretical interpretation have been connected, starring n-alkanes.Starting from the Gibbs adsorption equation thermodynamic relations between vapour adsorption and wetting are derived. The surface pressure of a film, formed by vapour adsorption on a solid surface, is calculated by integrating the vapour adsorption isotherm. The surface pressure at the sat...

  6. Effects of purge step on enrichment of low concentration oxygen-bearing coal mine methane based on proportion pressure swing adsorption%反吹过程对等比例变压吸附法分离富集低浓度含氧煤层气的影响

    Institute of Scientific and Technical Information of China (English)

    李永玲; 刘应书; 杨雄; 孟宇; 张传钊

    2012-01-01

    The safety of the adsorption process for low concentration (less than 30% ) coal mine methane was analyzed and studied based on the theory of coward explosion triangle, and then a new safe method for enriching low concentration coal mine methane, called the proportion pressure swing adsorption (PPSA) , was put forward. Furthermore , the effects of purge steps on the enrichment process for low concentration coal mine methane based on proportional pressure swing adsorption were investigated experimentally. The results show that purge steps are helpful to decreasing the oxygen and methane concentration in the exhaust gas, and the oxygen and methane concentration decrease with the increase of the purge time. But the purge steps also decrease the methane concentration in the product. So purge steps can be used in the PPSA process to make the oxygen concentration of the exhaust gas in the safe range and ensure the safety of the enrichment for low concentration coal mine. But the purge time should be appropriately controlled to prevent the methane concentration in the desorption gas from reducing too much.%在Coward爆炸三角形的基础上分析研究了低浓度煤层气(甲烷浓度低于30%)吸附富集过程的安全性,提出了一种安全分离富集低浓度煤层气的方法——等比例变压吸附(PPSA)法,并且通过实验研究了用PPSA法时增加反吹过程对低浓度煤层气吸附富集效果和安全性的影响.结果表明:循环步骤中设置反吹过程有利于降低排放气中甲烷和氧气的体积分数.反吹时间越长,排放气中甲烷和氧气体积分数越低,但会使解吸气即产品气中甲烷浓度降低.为了确保低浓度煤层气吸附富集过程的安全性,可以适当地对吸附塔进行反吹,降低排放气中氧气浓度,使之处于安全范围内.但是反吹时间不宜过长,以免使解吸气中甲烷浓度降低过多,使产品气品质不满足后续设备的使用要求.

  7. Stepped nozzle

    Science.gov (United States)

    Sutton, George P.

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  8. Interfacial adsorption of insulin - Conformational changes and reversibility of adsorption

    NARCIS (Netherlands)

    Mollmann, SH; Jorgensen, L; Bukrinsky, JT; Elofsson, U; Norde, W; Frokjaer, S

    2006-01-01

    The adsorption of human insulin to Teflon particles was studied with respect to conformational changes and the reversibility of adsorption was examined by total internal reflection fluorescence (TIRF). Adsorption isotherms for the adsorption of human insulin indicated high affinity adsorption, even

  9. Interfacial adsorption of insulin. Conformational changes and reversibility of adsorption

    NARCIS (Netherlands)

    Mollmann, S.H.; Bukrinsky, J.T.; Elofsson, U.; Norde, W.; Frokjaer, S.

    2006-01-01

    The adsorption of human insulin to Teflon particles was studied with respect to conformational changes and the reversibility of adsorption was examined by total internal reflection fluorescence (TIRF). Adsorption isotherms for the adsorption of human insulin indicated high affinity adsorption, even

  10. Kinetics of salicylic acid adsorption on activated carbon.

    Science.gov (United States)

    Polakovic, Milan; Gorner, Tatiana; Villiéras, Frédéric; de Donato, Philippe; Bersillon, Jean Luc

    2005-03-29

    The adsorption and desorption of salicylic acid from water solutions was investigated in HPLC microcolumns packed with activated carbon. The adsorption isotherm was obtained by the step-up frontal analysis method in a concentration range of 0-400 mg/L and was well fitted with the Langmuir equation. The investigation of rate aspects of salicylic acid adsorption was based on adsorption/desorption column experiments where different inlet concentrations of salicylic acid were applied in the adsorption phase and desorption was conducted with pure water. The concentration profiles of individual adsorption/desorption cycles data were fitted using several single-parameter models of the fixed-bed adsorption to assess the influence of different phenomena on the column behavior. It was found that the effects of axial dispersion and extraparticle mass transfer were negligible. A rate-determining factor of fixed-bed column dynamics was the kinetics of pore surface adsorption. A bimodal kinetic model reflecting the heterogeneous character of adsorbent pores was verified by a simultaneous fit of the column outlet concentration in four adsorption/desorption cycles. The fitted parameters were the fraction of mesopores and the adsorption rate constants in micropores and mesopores, respectively. It was shown that the former rate constant was an intrinsic one whereas the latter one was an apparent value due to the effects of pore blocking and diffusional hindrances in the micropores. PMID:15779975

  11. Adsorption dynamics of methyl violet onto granulated mesoporous carbon: Facile synthesis and adsorption kinetics.

    Science.gov (United States)

    Kim, Yohan; Bae, Jiyeol; Park, Hosik; Suh, Jeong-Kwon; You, Young-Woo; Choi, Heechul

    2016-09-15

    A new and facile one-step synthesis method for preparing granulated mesoporous carbon (GMC) with three-dimensional spherical mesoporous symmetry is prepared to remove large molecular weight organic compounds in aqueous phase. GMC is synthesized in a single step using as-synthesized mesoporous carbon particles and organic binders through a simple and economical synthesis approach involving a simultaneous calcination and carbonization process. Characterization results obtained from SEM, XRD, as well as surface and porosity analysis indicate that the synthesized GMC has similar physical properties to those of the powdered mesoporous carbon and maintains the Brunauer-Emmett-Teller (BET) surface area and pore volume because the new synthesis method prevents the collapse of the pores during the granulation process. Batch adsorption experiments revealed GMC showed a substantial adsorption capacity (202.8 mg/g) for the removal of methyl violet as a target large molecular contaminant in aqueous phase. The mechanisms and dynamics modeling of GMC adsorption were also fully examined, which revealed that surface diffusion was rate limiting step on adsorption process of GMC. Adsorption kinetics of GMC enables 3 times faster than that of granular activated carbon in terms of surface diffusion coefficient. This is the first study, to the best of our knowledge, to synthesize GMC as an adsorbent for water purification by using facile granulation method and to investigate the adsorption kinetics and characteristics of GMC. This study introduces a new and simple method for the synthesis of GMC and reveals its adsorption characteristics for large molecular compounds in a water treatment. PMID:27262123

  12. Application of stepping motor

    International Nuclear Information System (INIS)

    This book is divided into three parts, which is about practical using of stepping motor. The first part has six chapters. The contents of the first part are about stepping motor, classification of stepping motor, basic theory og stepping motor, characteristic and basic words, types and characteristic of stepping motor in hybrid type and basic control of stepping motor. The second part deals with application of stepping motor with hardware of stepping motor control, stepping motor control by microcomputer and software of stepping motor control. The last part mentions choice of stepping motor system, examples of stepping motor, measurement of stepping motor and practical cases of application of stepping motor.

  13. A Simple Adsorption Experiment

    Science.gov (United States)

    Guirado, Gonzalo; Ayllon, Jose A.

    2011-01-01

    The study of adsorption phenomenon is one of the most relevant and traditional physical chemistry experiments performed by chemistry undergraduate students in laboratory courses. In this article, we describe an easy, inexpensive, and straightforward way to experimentally determine adsorption isotherms using pieces of filter paper as the adsorbent…

  14. Phonon scattering in graphene over substrate steps

    Energy Technology Data Exchange (ETDEWEB)

    Sevinçli, H., E-mail: haldunsevincli@iyte.edu.tr [Department of Materials Science and Engineering, Izmir Institute of Technology, Gülbahçe Kampüsü, 35430 Urla, Izmir (Turkey); Department of Micro- and Nano-technology (DTU Nanotech), Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Brandbyge, M., E-mail: mads.brandbyge@nanotech.dtu.dk [Department of Micro- and Nano-technology (DTU Nanotech), Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Center for Nanostructured Graphene(CNG), Department of Micro- and Nano-technology, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark)

    2014-10-13

    We calculate the effect on phonon transport of substrate-induced bends in graphene. We consider bending induced by an abrupt kink in the substrate, and provide results for different step-heights and substrate interaction strengths. We find that individual substrate steps reduce thermal conductance in the range between 5% and 47%. We also consider the transmission across linear kinks formed by adsorption of atomic hydrogen at the bends and find that individual kinks suppress thermal conduction substantially, especially at high temperatures. Our analysis show that substrate irregularities can be detrimental for thermal conduction even for small step heights.

  15. Sticky steps inhibit step motions near equilibrium

    Science.gov (United States)

    Akutsu, Noriko

    2012-12-01

    Using a Monte Carlo method on a lattice model of a vicinal surface with a point-contact-type step-step attraction, we show that, at low temperature and near equilibrium, there is an inhibition of the motion of macrosteps. This inhibition leads to a pinning of steps without defects, adsorbates, or impurities (self-pinning of steps). We show that this inhibition of the macrostep motion is caused by faceted steps, which are macrosteps that have a smooth side surface. The faceted steps result from discontinuities in the anisotropic surface tension (the surface free energy per area). The discontinuities are brought into the surface tension by the point-contact-type step-step attraction. The point-contact-type step-step attraction also originates “step droplets,” which are locally merged steps, at higher temperatures. We derive an analytic equation of the surface stiffness tensor for the vicinal surface around the (001) surface. Using the surface stiffness tensor, we show that step droplets roughen the vicinal surface. Contrary to what we expected, the step droplets slow down the step velocity due to the diminishment of kinks in the merged steps (smoothing of the merged steps).

  16. Adsorption of tellurium ions by nickel oxide

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, W.J.; Bateman, J.M.

    1976-05-01

    This study was undertaken to investigate the mechanism of the adsorption process, and to provide chemistry data useful for the design of a Failed Fuel Detection and Location system for pressurized water power reactors. Such systems frequently operate by monitoring the level of a selected fission product in the coolant from each rod channel by means of its nuclear radiation. $sup 132$Te is a suitable nuclide for such monitoring and its adsorption on walls of a chamber offers a particularly simple and convenient preconcentration step. The method was to observe the depletion of tellurite ion from a solution of known initial concentration through adsorption by a NiO suspension. The activity of the samples and hence the tellurium concentration were measured with a Ge(Li) spectrometer, which permitted the 230 keV peak of $sup 132$Te to be isolated from the spectrum of the $sup 132$I daughter. The study shows that adsorption process proceeds by a dehydration reaction between -OH groups on the hydroxylated surface and similar groups on the adsorbing species. The equilibrium adsorption ratio is controlled by the solution pH by its effect on the relative distribution of the neutral, monobasic and dibasic tellurite species via the two acid ionization constants.

  17. Competitive Protein Adsorption - Multilayer Adsorption and Surface Induced Protein Aggregation

    DEFF Research Database (Denmark)

    Holmberg, Maria; Hou, Xiaolin

    2009-01-01

    In this study, competitive adsorption of albumin and IgG (immunoglobulin G) from human serum solutions and protein mixtures onto polymer surfaces is studied by means of radioactive labeling. By using two different radiolabels (125I and 131I), albumin and IgG adsorption to polymer surfaces...... is monitored simultaneously and the influence from the presence of other human serum proteins on albumin and IgG adsorption, as well as their mutual influence during adsorption processes, is investigated. Exploring protein adsorption by combining analysis of competitive adsorption from complex solutions...... of high concentration with investigation of single protein adsorption and interdependent adsorption between two specific proteins enables us to map protein adsorption sequences during competitive protein adsorption. Our study shows that proteins can adsorb in a multilayer fashion onto the polymer surfaces...

  18. The Adsorption Effect of Quaternized Chitosan Derivatives on Bile Acid

    Institute of Scientific and Technical Information of China (English)

    Shu Xian MENG; Ya Qing FENG; Wen Jin LI; Cai Xia YIN; Jin Ping DENG

    2006-01-01

    Three quaternized chitosan derivatives were synthesized and their adsorption performance of bile acid from aqueous solution was studied. The adsorption capacities and rates of bile acid onto quaternized chitosan derivatives were evaluated. The kinetic experimental data properly correlated with the second-order kinetic model, which indicated that the chemical sorption is the rate-limiting step. The results showed that the quaternized chitosan derivatives are favorable adsorbents for bile acid.

  19. Adsorption and regenerative oxidation of trichlorophenol with synthetic zeolite: Ozone dosage and its influence on adsorption performance.

    Science.gov (United States)

    Zhang, Yongjun; Prigent, Bastien; Geißen, Sven-Uwe

    2016-07-01

    Regeneration of loaded adsorbents is a key step for the sustainability of an adsorption process. In this study, ozone was applied to regenerate a synthetic zeolite for the adsorption of trichlorophenol (TCP) as an organic model pollutant. Three initial concentrations of TCP in water phase were used in adsorption tests. After the equilibrium, zeolite loaded different amounts of TCP was dried and then regenerated with ozone gas. It was found that the adsorption capacity of zeolite was increased through three regeneration cycles. However, the adsorption kinetics was compromised after the regeneration with slightly declined 2nd order reaction constants. The ozone demand for the regeneration was highly dependent on the TCP mass loaded onto the zeolite. It was estimated that the mass ratio of ozone to TCP was 1.2 ± 0.3 g O3/g TCP. PMID:27043379

  20. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  1. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  2. Liquid-liquid extraction and adsorption on solid surfaces applied to used lubricant oils recovery

    OpenAIRE

    J. L. Assunção Filho; L. G. M. Moura; A.C.S. RAMOS

    2010-01-01

    In this work, the recovery of base oils from waste lubricants following the steps of solvent extraction, adsorption on solids and solvent removal by evaporation was evaluated. In the step of solvent extraction, the most efficient was 1-butanol, followed by tert-butanol, 2-propanol and ethanol; for the step of adsorption, activated carbon was the most effective solid for PAH removal, confirming the similarity of these compounds with petroleum aromatic fractions. Thus, the optimum solvent-adsor...

  3. Adsorption behaviour of bulgur.

    Science.gov (United States)

    Erbaş, Mustafa; Aykın, Elif; Arslan, Sultan; Durak, Atike N

    2016-03-15

    The aim of this research was to determine the adsorption behaviour of bulgur. Three different particle sizes (2dry matter and 4.96-16.57, respectively. Constant k was between 0.85 and 0.93, and GAB equation was determined to fit very well for bulgur adsorption, because of %E values lower than 10%. Bulgur must be stored below 70% relative humidity and with less than 10 g water per 100 g of dry mater. PMID:26575716

  4. Cu and Cd Adsorption on Carbon Aerogel and Xerogel

    Directory of Open Access Journals (Sweden)

    Cotet L. C.

    2013-04-01

    Full Text Available Carbon aerogel (CA and xerogel (CX were proposed as new carbon adsorbent materials for Cu and Cd ions from contaminated water (synthetic water samples. These materials were prepared by a sol-gel process that involves a polycondensation of resorcinol and formaldehyde in Na2CO3 catalysis, followed by a drying step, either in supercritical conditions of CO2 to aerogel obtaining or in normal conditions to xerogel obtaining, and a pyrolytic step. Nitrogen adsorption, AFM, SEM, TEM and XRD were used for morpho-structural adsorbent investigation. Cu and Cd ions adsorption experiments were carried out in batch conditions under magnetic stirring. Adsorbent quantity and grain size influence over the adsorption efficiency were considered. Adsorption results expressed as adsorption capacities showed that prepared CA is a better adsorbent than CX. Adsorption capacities up to 14.2 mg g-1 and 8.5 mg g-1 were obtained for Cd2+ and Cu2+ adsorption on CA, respectively.

  5. Adsorption of Pyrene onto the Agricultural By-Product: Corncob.

    Science.gov (United States)

    Li, Xiaojun; Tong, Dongli; Allinson, Graeme; Jia, Chunyun; Gong, Zongqing; Liu, Wan

    2016-01-01

    The adsorption behavior of pyrene on corncob was studied to provide a theoretical basis for the possible use of this material as an immobilized carrier for improving the bioremediation of PAH-contaminated soil. The results were as follows. Kinetic experiments showed that the adsorption processes obeyed a pseudo-second-order model. The intraparticle diffusion of Weber-Morris model fitting showed that the film and intraparticle diffusions were the key rate-limiting processes, and the adsorption process mainly consisted of three steps: boundary layer diffusion and two intra-particle diffusions. Experimental adsorption data for pyrene were successfully described by the adsorption-partition equilibrium model. The maximum adsorption capacity at 25°C was 214.8 μg g(-1). The adsorption contribution decreased significantly when the Ce/Sw (the equilibrium concentration/solubility in water) was higher than 1. Adsorption decreased with increased temperature. Based on the above results, the corncob particles could be helpful in the bioremediation of pyrene-contaminated soil.

  6. Dynamics and thermodynamics of toxic metals adsorption onto soil-extracted humic acid.

    Science.gov (United States)

    Shaker, Medhat A; albishri, Hassan M

    2014-09-01

    Humic acids, HA represent a large portion of natural organic matter in soils, sediments and waters. They are environmentally important materials due to their extensive ubiquity and strong complexation ability, which can influence heavy metal removal and transportation in waters. The thermodynamics and kinetics of the adsorption of Cd(II) and Cr(VI) onto solid soil-derived HA have been investigated at optimum conditions of pH (5.5±0.1), metal concentration (10-100mmolL(-1)) and different temperatures (293-323K). The suitability of adsorption models such as Freundlich and Langmuir to equilibrium data was investigated. The adsorption was well described by Langmuir isotherm model in multi-detectable steps. Adsorption sites, i (i=A, B, C) with different capacities, νi are characterized. The stoichiometric site capacity is independent of temperature and equilibrium constant, Ki. Adsorption sites A and B are selectively occupied by Cr(VI) cations while sites A and C are selectively occupied by Cd(II) cations. The thermodynamic parameters of adsorption systems are correlated for each adsorption step. The adsorption is endothermic, spontaneous and favorable. Different kinetic models are applied and the adsorption of these heavy metals onto HA follows pseudo-second-order kinetics and equilibrium is achieved within 24h. The adsorption reaction is controlled by diffusion processes and the type of the adsorption is physical. PMID:24997970

  7. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    Science.gov (United States)

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  8. Dissociative adsorption of methane on surface oxide structures of Pd-Pt alloys

    OpenAIRE

    Dianat, Arezoo; Seriani, Nicola; Ciacchi, Lucio Colombi; Pompe, Wolfgang; Cuniberti, Gianaurelio; Bobeth, Manfred

    2010-01-01

    The dissociative adsorption of methane on variously oxidized Pd, Pt and Pd-Pt surfaces is investigated using density-functional theory, as a step towards understanding the combustion of methane on these materials. For Pd-Pt alloys, models of surface oxide structures are built on the basis of known oxides on Pd and Pt. The methane adsorption energy presents large variations depending on the oxide structure and composition. Adsorption is endothermic on the bare Pd(111) metal surface as well as ...

  9. Regenerative adsorption distillation system

    KAUST Repository

    Ng, Kim Choon

    2013-12-26

    There is provided a regenerative adsorption distillation system comprising a train of distillation effects in fluid communication with each other. The train of distillation effects comprises at least one intermediate effect between the first and last distillation effects of the train, each effect comprising a vessel and a condensing tube for flow of a fluid therein. The system further comprises a pair of adsorption-desorption beds in vapour communication with the last effect and at least one intermediate effect, wherein the beds contain an adsorbent that adsorbs vapour from the last effect and transmits desorbed vapour into at least one of the intermediate effect.

  10. Neon and CO2 adsorption on open carbon nanohorns.

    Science.gov (United States)

    Krungleviciute, Vaiva; Ziegler, Carl A; Banjara, Shree R; Yudasaka, Masako; Iijima, S; Migone, Aldo D

    2013-07-30

    We present the results of a thermodynamics and kinetics study of the adsorption of neon and carbon dioxide on aggregates of chemically opened carbon nanohorns. Both the equilibrium adsorption characteristics, as well as the dependence of the kinetic behavior on sorbent loading, are different for these two adsorbates. For neon the adsorption isotherms display two steps before reaching the saturated vapor pressure, corresponding to adsorption on strong and on weak binding sites; the isosteric heat of adsorption is a decreasing function of sorbent loading (this quantity varies by about a factor of 2 on the range of loadings studied), and the speed of the adsorption kinetics increases with increasing loading. By contrast, for carbon dioxide there are no substeps in the adsorption isotherms; the isosteric heat is a nonmonotonic function of loading, the value of the isosteric heat never differs from the bulk heat of sublimation by more than 15%, and the kinetic behavior is opposite to that of neon, with equilibration times increasing for higher sorbent loadings. We explain the difference in the equilibrium properties observed for neon and carbon dioxide in terms of differences in the relative strengths of adsorbate-adsorbate to adsorbate-sorbent interaction for these species.

  11. Albumin adsorption on oxide thin films studied by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva-Bermudez, P., E-mail: suriel21@yahoo.com [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico); Unidad de Posgrado, Facultad de Odontologia, Universidad Nacional Autonoma de Mexico, CU, 04510, Mexico D.F. (Mexico); Rodil, S.E.; Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito Exterior s/n, C.U., 04510, Mexico D.F. (Mexico)

    2011-12-15

    Thin films of tantalum, niobium, zirconium and titanium oxides were deposited by reactive magnetron sputtering and their wettability and surface energy, optical properties, roughness, chemical composition and microstructure were characterized using contact angle measurements, spectroscopic ellipsometry, profilometry, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The purpose of the work was to correlate the surface properties of the films to the Bovine Serum Albumin (BSA) adsorption, as a first step into the development of an initial in vitro test of the films biocompatibility, based on standardized protein adsorption essays. The films were immersed into BSA solutions with different protein concentrations and protein adsorption was monitored in situ by dynamic ellipsometry; the adsorption-rate was dependent on the solution concentration and the immersion time. The overall BSA adsorption was studied in situ using spectroscopic ellipsometry and it was found to be influenced by the wettability of the films; larger BSA adsorption occurred on the more hydrophobic surface, the ZrO{sub 2} film. On the Ta{sub 2}O{sub 5}, Nb{sub 2}O{sub 5} and TiO{sub 2} films, hydrophilic surfaces, the overall BSA adsorption increased with the surface roughness or the polar component of the surface energy.

  12. Kinetics and isotherms of Neutral Red adsorption on peanut husk

    Institute of Scientific and Technical Information of China (English)

    HAN Runping; HAN Pan; CAI Zhaohui; ZHAO Zhenhui; TANG Mingsheng

    2008-01-01

    Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carded out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Toth isotherm models. The results indicated that the Toth and Langmuir models provided the best correlation of the experimental data. The adsorption capacity of peanut husk for the removal of NR was determined with the Langmuir and found to be 37.5 mg/g at 295 K. The adsorption kinetic data were modeled using the pseudo-first order, pseudo-second order, and intra-particle diffusion kinetic equations. It was seen that the pseudo-first order and pseudo-second order kinetic equations could describe the adsorption kinetics. The intraparticle diffusion model was also used to express the adsorption process at the two-step stage. It was implied that peanut husk may be suitable as adsorbent material for adsorption of NR from aqueous solutions.

  13. Internship guide : Work placements step by step

    NARCIS (Netherlands)

    Haag, Esther

    2013-01-01

    Internship Guide: Work Placements Step by Step has been written from the practical perspective of a placement coordinator. This book addresses the following questions : what problems do students encounter when they start thinking about the jobs their degree programme prepares them for? How do you fi

  14. The way to collisions, step by step

    CERN Multimedia

    2009-01-01

    While the LHC sectors cool down and reach the cryogenic operating temperature, spirits are warming up as we all eagerly await the first collisions. No reason to hurry, though. Making particles collide involves the complex manoeuvring of thousands of delicate components. The experts will make it happen using a step-by-step approach.

  15. Fluor-ferro-leakeite, NaNa2(FC2+2Fe3+2Li)Si8O22F2, a new alkali amphibole from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.

    Science.gov (United States)

    Hawthorne, F.C.; Oberti, R.; Ungaretti, L.; Ottolini, L.; Grice, Joel D.; Czamanske, G.K.

    1996-01-01

    Fluor-ferro-leakeite is a new amphibole species from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.; it occurs in association with quartz, alkali feldspar, acmite, ilmenite, and zircon. It forms as anhedral bluish black crystals elongated along c and up to 1 mm long. It is brittle, H = 6, Dmeas = 3.37 g/cm3, Dcalc = 3.34 g/cm3. In plane-polarized light, it is strongly pleochroic, X = very dark indigo blue, Y = gray blue, Z = yellow green; X ??? c = 10?? (in ??obtuse), Y = b, Z ??? a = 4?? (in ?? obtuse), with absorption X > Y > Z. Fluor-ferro-leakeite is biaxial positive, ?? = 1.675(2), ??= 1.683(2), ?? = 1.694(1); 2V = 87(2)??; dispersion is not visible because of the strong absorption. Fluor-ferro-leakeite is monoclinic, space group C2/m, a = 9.792(1), b = 17.938(1), c = 5.3133(4) A??, ??= 103.87(7)??, V = 906.0(1) A??3, Z = 2. The ten strongest X-ray diffraction lines in the powder pattern are [d(I,hkl)]: 2.710(100,151), 2.536(92,202), 3.404(57,131), 4.481(54,040), 8.426(45,110), 2.985(38,241), 2.585(38,061), 3.122(29,310), 2.165(26,261), and 1.586(25,403). Analysis by a combination of electron microprobe, ion microprobe, and crystal-structure refinement (Hawthorne et al. 1993) gives SiO2 51.12, Al2O3 1.13, TiO2 0.68, Fe2O3 16.73, FeO 8.87, MgO 2.02, MnO 4.51, ZnO 0.57, CaO 0.15, Na2O 9.22, K2O 1.19, Li2O 0.99, F 2.87, H2Ocalc 0.60, sum 99.44 wt%. The formula unit, calculated on the basis of 23 O atoms, is (K0.23Na0.76)(Na1.97Ca0.03)(Mg 0.46Fe2+1.4Mn2+0.59Zn0.07Fe3+1.93-Ti 0.08Al0.02Li0.61])(Si7.81Al 0.19)O22(F1.39OH0.61). A previous crystal-structure refinement (Hawthorne et al. 1993) shows Li to be completely ordered at the M3 site. Fluor-ferro-leakeite, ideally NaNa2(Fe2+2Fe3+2Li)Si8O22F2, is related to leakeite, NaNa2(Mg2Fe3+3Li)Si 8O22(OH)2, by the substitutions Fe2+ ??? Mg and F ??? OH.

  16. Carbonaceous materials for adsorptive refrigerators

    Science.gov (United States)

    Buczek, B.; Wolak, E.

    2012-06-01

    Carbon monoliths prepared from hard coal precursors were obtained. The porous structure of the monoliths was evaluated on the basis of nitrogen adsorption — desorption equilibrium data. The investigated monoliths have a well-developed microporous structure with significant specific surface area (S BET ). Equilibrium studies of methanol vapour adsorption were used to characterize the methanol adsorptive capacity that was determined using a volumetric method. The heat of wetting by methanol was determined in order to estimate the energetic effects of the adsorption process. The results of the investigations show that all monoliths exhibit high adsorption capacity and high heat of wetting with methanol.

  17. ADSORPTION OF 1,2,4-ACID BY WEAKLY BASIC RESIN:ISOTHERMS,THERMODYNAMICS AND KINETICS

    Institute of Scientific and Technical Information of China (English)

    Fu-qiang Liu; Jin-long Chen; Chao Long; Ai-min Li; Guan-dao Gao; Quan-xing Zhang

    2004-01-01

    The adsorption properties, including the adsorption isotherms, thermodynamics and kinetics, of 1-arnino-2-naphthol-4-sulfonic acid (1,2,4-acid) onto weakly basic resin ND900 are investigated. Both the Langmuir and Freundlich equations can give a good fit to the adsorption isotherms, which indicates an endothermic and a favorable adsorption in our study range. A high yield in elimination of about 45.21%-97.28% is obtained for the tested adsorption systems. The capacity and affinity of the adsorption increase with temperature, due to the phenomena of "solvent-motivated" effects. The value of △H is 51.59 kJ/mol, which indicates a chemical adsorption and then expects the poor desorption property of ND900. The negative value of AG indicates the spontaneous nature of the adsorption process, and the positive value of △S shows the increased randomness at the solid/solution interface during the adsorption process. The value of the adsorption rate constant lower than 0.013 min-1 is indicative of a slow adsorption rate. The intra-particle diffusion must be one of the rate limiting steps.

  18. Microsoft Office professional 2010 step by step

    CERN Document Server

    Cox, Joyce; Frye, Curtis

    2011-01-01

    Teach yourself exactly what you need to know about using Office Professional 2010-one step at a time! With STEP BY STEP, you build and practice new skills hands-on, at your own pace. Covering Microsoft Word, PowerPoint, Outlook, Excel, Access, Publisher, and OneNote, this book will help you learn the core features and capabilities needed to: Create attractive documents, publications, and spreadsheetsManage your e-mail, calendar, meetings, and communicationsPut your business data to workDevelop and deliver great presentationsOrganize your ideas and notes in one placeConnect, share, and accom

  19. Spectroscopic evidence for the adsorption of propene on gold nanoparticles Spectroscopic evidence for the adsorption of propene on gold nanoparticles

    NARCIS (Netherlands)

    Nijhuis, T.A.; Sacaliuc, E.; Beale, A.M.; van der Eerden, A.M.J.; Schouten, J.C.; Weckhuysen, B.M.

    2008-01-01

    The adsorption of propene on supported gold nanoparticles has been experimentally identified as a reaction step in the hydro-epoxidation of propene. This new finding was made possible by applying a detailed analysis of in situ measured XANES spectra. For this purpose, gold-on-silica catalysts were i

  20. Double-Stranded Water on Stepped Platinum Surfaces

    Science.gov (United States)

    Kolb, Manuel J.; Farber, Rachael G.; Derouin, Jonathan; Badan, Cansin; Calle-Vallejo, Federico; Juurlink, Ludo B. F.; Killelea, Daniel R.; Koper, Marc T. M.

    2016-04-01

    The interaction of platinum with water plays a key role in (electro)catalysis. Herein, we describe a combined theoretical and experimental study that resolves the preferred adsorption structure of water wetting the Pt(111)-step type with adjacent (111) terraces. Double stranded lines wet the step edge forming water tetragons with dissimilar hydrogen bonds within and between the lines. Our results qualitatively explain experimental observations of water desorption and impact our thinking of solvation at the Pt electrochemical interface.

  1. Alkali treated Foumanat tea waste as an efficient adsorbent for methylene blue adsorption from aqueous solution

    Directory of Open Access Journals (Sweden)

    Azadeh Ebrahimian Pirbazari

    2014-08-01

    Full Text Available The adsorption of methylene blue (MB from aqueous solution by alkali treated Foumanat tea waste (ATFTW from agriculture biomass was investigated. The adsorbent was characterized by Scanning Electron Microscopy (SEM, Fourier Transform-Infrared Spectroscopy (FT-IR and nitrogen physisorption. FTIR results showed complexation and ion exchange appear to be the principle mechanism for MB adsorption. The adsorption isotherm data were fitted to Langmuir, Sips, Redlich-Peterson and Freundlich equations, and the Langmuir adsorption capacity, Qmax was found to be 461 mgg−1. It was found that the adsorption of MB increases by increasing temperature from 303 to 323 K and the process is endothermic in nature. The removal of MB by ATFTW followed pseudo-second order reaction kinetics based on Lagergren equations. Mechanism studies indicated that the adsorption of MB on the ATFTW was mainly governed by external mass transport where particle diffusion was the rate limiting step.

  2. 耐热聚乙烯管材专用树脂QHM22F的性能及加工应用%Properties, processing and application of special polyethylene resin QHM22F of raised temperature resistance for pipes

    Institute of Scientific and Technical Information of China (English)

    王群涛; 郭锐; 王日辉; 高凌雁; 许平; 石晶

    2014-01-01

    研究了工业化生产的耐热聚乙烯(PE-RT)管材专用树脂QHM22F的常规物性、加工稳定性、加工性能等,并在不同管材生产线上进行了加工应用试验。结果表明:QHM22F的简支梁缺口冲击强度在70kJ/m2以上;200℃氧化诱导期大于120min;耐压等级达到PE-RTⅡ型;QHM22F的加工性能良好,可满足高速牵引(36.1m/min)的加工需要;采用QHM22F生产的管材内外表面光滑、壁厚均匀,性能满足用户要求。%The authors studied basic physical properties, processing stability, processability, etc. of commercial special polyethylene resin of raised temperature resistance (PE-RT) for pipes, grade QHM22F. The processing application experiments of the resin were carried out on different pipe extrusion equipments. The results indicate that the Charpy notched impact strength of QHM22F is above 70 kJ/m2 and the oxidation induction time at 200 ℃ of QHM22F is over 120 min. Grade certification of QHM22F is PE-RT type Ⅱ. QHM22F has excellent processability which can meet the requirements of high pulling speed (36.1 m/min). The pipe made of QHM22F with uniform thickness and smooth inner and outer surface can satisfy the users' requirements.

  3. A REVIEW OF HEAVY METAL ADSORPTION BY MARINE ALGAE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Accumulation of heavy metals by algae had been studied extensively for biomonitoring or bioremediation purposes. Having the advantages of low cost raw material, big adsorbing capacity, no secondary pollution, etc., algae may be used to treat industrial water containing heavy metals. The adsorption processes were carried out in two steps: rapid physical adsorption first, and then slow chemical adsorption. pH is the major factor influencing the adsorption. The Freundlich equation fitted very well the adsorption isotherms. The uptake decreased with increasing ionic strength. The principal mechanism of metallic cation sequestration involves the formation of complexes between a metal ion and functional groups on the surface or inside the porous structure of the biological material. The carboxyl groups of alginate play a major role in the complexation. Different species of algae and the algae of the same species may have different adsorption capacity. Their selection affinity for heavy metals was the major criterion for the screening of a biologic adsorbent to be used in water treatment. The surface complex formation model (SCFM) can solve the equilibrium and kinetic problems in the biosorption.

  4. Adsorption of dyes onto activated carbon prepared from olive stones

    Institute of Scientific and Technical Information of China (English)

    Souad NAJAR-SOUISSI; Abdelmottaleb OUEDERNI; Abdelhamid RATEL

    2005-01-01

    Activated carbon was produced from olive stones(OSAC) by a physical process in two steps. The adsorption character of this activated carbon was tested on three colour dyes molecules in aqueous solution: Methylene blue(MB), Rhodamine B(RB) and Congo Red(CR). The adsorption equilibrium was studied through isotherms construction at 30℃, which were well described by Langmuir model.The adsorption capacity on the OSAC was estimated to be 303 mg/g, 217 mg/g and 167 mg/g respectively for MB, RB and CR. This activated carbon has a similar adsorption properties to that of commercial ones and show the same adsorption performances. The adsorption kinetics of the MB molecule in aqueous solution at different initial concentrations by OSAC was also studied. Kinetic experiments were well fitted by a simple intra-particle diffusion model. The measured kinetics constant was influenced by the initial concentration and we found the following correlation: Kid = 1.55 C00.51 .

  5. Adsorption de composés organiques volatils et régénération de charbons actifs - Developpement d'outils de simulation

    OpenAIRE

    Ramalingam, Shivaji Ganesan

    2012-01-01

    Organic vapors emitted from solvents used in chemical / food / pharmaceutical processes, or from hydrocarbon fuel storage stations at oil terminals, can be efficiently captured by adsorption onto activated carbon beds. The overall objective of the research program is the experimental and simulation studies of the adsorption and regeneration steps in the case of VOC removal which accounts into industrial emissions by Temperature Swing Adsorption (TSA) and Vacuum Temperature Swing Adsorption (V...

  6. Copper adsorption in tropical oxisols

    Directory of Open Access Journals (Sweden)

    Silveira Maria Lucia Azevedo

    2003-01-01

    Full Text Available Cu adsorption, at concentrations between 0 to 800 mg L-1, was evaluated in surface and subsurface samples of three Brazilian soils: a heavy clayey-textured Rhodic Hapludalf (RH, a heavy clayey-textured Anionic ''Rhodic'' Acrudox (RA and a medium-textured Anionic ''Xanthic'' Acrudox (XA. After adsorption, two consecutive extractions were performed to the samples which received 100 mg L-1 copper. Surface samples adsorbed higher amounts of Cu than the subsurface, and exhibited lower Cu removed after the extractions, reinforcing the influence of the organic matter in the reactions. Cu adsorption was significant in the subsurface horizons of the Oxisols, despite the positive balance of charge, demonstrating the existence of mechanisms for specific adsorption, mainly related to the predominance of iron and aluminum oxides in the mineral fractions. In these samples, Cu was easily removed from the adsorption sites. RH demonstrated a higher capacity for the Cu adsorption in both horizons.

  7. Computational Abstraction Steps

    DEFF Research Database (Denmark)

    Thomsen, Lone Leth; Thomsen, Bent; Nørmark, Kurt

    2010-01-01

    In this paper we discuss computational abstraction steps as a way to create class abstractions from concrete objects, and from examples. Computational abstraction steps are regarded as symmetric counterparts to computational concretisation steps, which are well-known in terms of function calls...... or capturing concrete values, objects, or actions. As the next step, some of these are lifted to a higher level by computational means. In the object-oriented paradigm the target of such steps is classes. We hypothesise that the proposed approach primarily will be beneficial to novice programmers or during...

  8. Step by Step Microsoft Office Visio 2003

    CERN Document Server

    Lemke, Judy

    2004-01-01

    Experience learning made easy-and quickly teach yourself how to use Visio 2003, the Microsoft Office business and technical diagramming program. With STEP BY STEP, you can take just the lessons you need, or work from cover to cover. Either way, you drive the instruction-building and practicing the skills you need, just when you need them! Produce computer network diagrams, organization charts, floor plans, and moreUse templates to create new diagrams and drawings quicklyAdd text, color, and 1-D and 2-D shapesInsert graphics and pictures, such as company logosConnect shapes to create a basic f

  9. Adsorption design for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Cooney, D.O.

    1998-12-31

    Understand the premier method for removing organic contaminants from water. Straight forward explanations and illustrations allow this overview to fill a dual purpose: study manual and design guide. The book discusses basic properties of activated carbons; explains the kinetics of adsorption processes; describes the design of both fixed-bed and batch process adsorption systems; contains useful knowledge that can be extended to other applications of adsorption, including drinking water treatment; and includes many illustrated examples and practice exercises.

  10. Adsorption of polyhydroxyl based surfactants

    OpenAIRE

    Matsson, Maria

    2005-01-01

    Adsorption on solid surfaces from solution is a fundamental property of a surfactant. It might even be the most important aspect of surfactant behavior, since it influences many applications, such as cleaning, detergency, dispersion, separation, flotation, and lubrication. Consequently, fundamental investigations of surfactant adsorption are relevant to many areas. The main aim of this thesis has been to elucidate the adsorption properties, primarily on the solid/water interface, of a particu...

  11. Optimization of adsorptive immobilization of alcohol dehydrogenases.

    Science.gov (United States)

    Trivedi, Archana; Heinemann, Matthias; Spiess, Antje C; Daussmann, Thomas; Büchs, Jochen

    2005-04-01

    In this work, a systematic examination of various parameters of adsorptive immobilization of alcohol dehydrogenases (ADHs) on solid support is performed and the impact of these parameters on immobilization efficiency is studied. Depending on the source of the enzymes, these parameters differently influence the immobilization efficiency, expressed in terms of residual activity and protein loading. Residual activity of 79% was achieved with ADH from bakers' yeast (YADH) after optimizing the immobilization parameters. A step-wise drying process has been found to be more effective than one-step drying. A hypothesis of deactivation through bubble nucleation during drying of the enzyme/glass bead suspension at low drying pressure (300% residual activity was found after drying. Hyperactivation of the enzyme is probably caused by structural changes in the enzyme molecule during the drying process. ADH from Thermoanaerobacter species (ADH T) is found to be stable under drying conditions (>15 kPa) in contrast to LBADH and YADH.

  12. Modeling two-rate adsorption kinetics: Two-site, two-species, bilayer and rearrangement adsorption processes.

    Science.gov (United States)

    Tripathi, Sumit; Tabor, Rico F

    2016-08-15

    The adsorption kinetics of many systems show apparent two-rate processes, where there appears to be resolved fast and slow adsorption steps. Such non-standard adsorption processes cannot be accounted for by conventional modeling methods, motivating new approaches. In this work, we present four different models that can account for two-rate adsorption and are based upon physically realistic processes - two adsorbing species, two surface sites having different energies, bilayer formation and molecular rearrangement modes. Each model is tested using a range of conditions, and the characteristic behavior is explored and compared. In these models, the effects of mass transport and bulk concentration are also accounted for, making them applicable in systems which are transport-limited or attachment-limited, or intermediate between the two. The applicability of these models is demonstrated by fitting exemplar experimental data for each of the four models, selecting the model on the basis of the known physical behavior of the adsorption kinetics. These models can be applied in a wide range of systems, from stagnant adsorption in large volume water treatment to highly dynamic flow conditions relevant to printing, coating and processing applications. PMID:27209397

  13. Extremely high negative electron affinity of diamond via magnesium adsorption

    OpenAIRE

    O'Donnell, Kane M.; Edmonds, Mark T.; Tadich, Anton; Thomsen, Lars; Stacey, Alastair; Schenk, Alex; Pakes, Chris I.; Ley, Lothar

    2015-01-01

    We report large negative electron affinity (NEA) on diamond (100) using magnesium adsorption on a previously oxygen-terminated surface. The measured NEA is up to $(-2.01\\pm0.05)$ eV, the largest reported negative electron affinity to date. Despite the expected close relationship between the surface chemistry of Mg and Li species on oxygen-terminated diamond, we observe differences in the adsorption properties between the two. Most importantly, a high-temperature annealing step is not required...

  14. Adsorption and collective paramagnetism

    CERN Document Server

    Selwood, Pierce W

    1962-01-01

    Adsorption and Collective Paramagnetism describes a novel method for studying chemisorption. The method is based on the change in the number of unpaired electrons in the adsorbent as chemisorption occurs. The method is applicable to almost all adsorbates, but it is restricted to ferromagnetic adsorbents such as nickel, which may be obtained in the form of very small particles, that is to say, to ferromagnetic adsorbents with a high specific surface. While almost all the data used illustratively have been published elsewhere this is the first complete review of the subject. The book is addresse

  15. Diabetes PSA (:60) Step By Step

    Centers for Disease Control (CDC) Podcasts

    2009-10-24

    First steps to preventing diabetes. For Hispanic and Latino American audiences.  Created: 10/24/2009 by National Diabetes Education Program (NDEP), a joint program of the Centers for Disease Control and Prevention and the National Institutes of Health.   Date Released: 10/24/2009.

  16. Diabetes PSA (:30) Step By Step

    Centers for Disease Control (CDC) Podcasts

    2009-10-24

    First steps to preventing diabetes. For Hispanic and Latino American audiences.  Created: 10/24/2009 by National Diabetes Education Program (NDEP), a joint program of the Centers for Disease Control and Prevention and the National Institutes of Health.   Date Released: 10/24/2009.

  17. Cyclic steps on ice

    Science.gov (United States)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  18. Removal of furan and phenolic compounds from simulated biomass hydrolysates by batch adsorption and continuous fixed-bed column adsorption methods.

    Science.gov (United States)

    Lee, Sang Cheol; Park, Sunkyu

    2016-09-01

    It has been proposed to remove all potential inhibitors and sulfuric acid in biomass hydrolysates generated from dilute-acid pretreatment of biomass, based on three steps of sugar purification process. This study focused on its first step in which furan and phenolic compounds were selectively removed from the simulated hydrolysates using activated charcoal. Batch adsorption experiments demonstrated that the affinity of activated charcoal for each component was highest in the order of vanillic acid, 4-hydroxybenzoic acid, furfural, acetic acid, sulfuric acid, and xylose. The affinity of activated charcoal for furan and phenolic compounds proved to be significantly higher than that of the other three components. Four separation strategies were conducted with a combination of batch adsorption and continuous fixed-bed column adsorption methods. It was observed that xylose loss was negligible with near complete removal of furan and phenolic compounds, when at least one fixed-bed column adsorption was implemented in the strategy. PMID:27289057

  19. Impact of biochar produced from post-harvest residue on the adsorption behavior of diesel oil on loess soil.

    Science.gov (United States)

    Jiang, Yu Feng; Sun, Hang; Yves, Uwamungu J; Li, Hong; Hu, Xue Fei

    2016-02-01

    The primary objective of this study was to investigate the effect of biochar, produced from wheat residue at different temperatures, on the adsorption of diesel oil by loess soil. Kinetic and equilibrium data were processed to understand the adsorption mechanism of diesel by biochar-affected loess soil; dynamic and thermodynamic adsorption experiments were conducted to characterize this adsorption. The surface features and chemical structure of biochar, modified at varying pyrolytic temperatures, were investigated using surface scanning electron microscopy and Fourier transform infrared analysis. The kinetic data showed that the adsorption of diesel oil onto loess soil could be described by a pseudo-second-order kinetic model, with the rate-controlling step being intraparticle diffusion. However, in the presence of biochar, boundary layer control and intraparticle diffusion were both involved in the adsorption. Besides, the adsorption equilibrium data were well described by the Freundlich isothermal model. The saturated adsorption capacity weakened as temperature increased, suggesting a spontaneous exothermic process. Thermodynamic parameter analysis showed that adsorption was mainly a physical process and was enhanced by chemical adsorption. The adsorption capacity of loess soil for diesel oil was weakened with increasing pH. The biochar produced by pyrolytic wheat residue increased the adsorption behavior of petroleum pollutants in loess soil.

  20. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jing [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); College of Environmental Science and Engineering, Yangzhou University, 196 West Huayang Road, Yangzhou 225127 (China); Lv, Lu, E-mail: esellu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Lan, Pei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); College of Environmental Science and Engineering, Yangzhou University, 196 West Huayang Road, Yangzhou 225127 (China); Zhang, Shujuan [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Pan, Bingcai, E-mail: bcpan@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Zhang, Weiming [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer The presence of EfOM significantly reduced the adsorption capacities and rates of PFCs. Black-Right-Pointing-Pointer Low-molecular-weight EfOM compounds (<1 kDa) compete for adsorption sites of PFSs directly. Black-Right-Pointing-Pointer Large-molecular-weight EfOM compounds (>30 kDa) affect the adsorption through pore blockage or restriction effect. Black-Right-Pointing-Pointer Changes in surface properties of PAC caused by preloaded EfOM could affect PFCs adsorption. - Abstract: Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (<1 kDa) were found to be the major contributors to the significant reduction in PFC adsorption capacity, while large-molecular-weight compounds (>30 kDa) had much less effect on PFC adsorption capacity.

  1. Microsoft Office Word 2007 step by step

    CERN Document Server

    Cox, Joyce

    2007-01-01

    Experience learning made easy-and quickly teach yourself how to create impressive documents with Word 2007. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them!Apply styles and themes to your document for a polished lookAdd graphics and text effects-and see a live previewOrganize information with new SmartArt diagrams and chartsInsert references, footnotes, indexes, a table of contentsSend documents for review and manage revisionsTurn your ideas into blogs, Web pages, and moreYour all-in-one learning experience includes:Files for building sk

  2. Golgi-Cox Staining Step by Step

    OpenAIRE

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field.

  3. Golgi-Cox staining step by step

    OpenAIRE

    Sami eZaqout; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field.

  4. Liquid-Phase Adsorption Fundamentals.

    Science.gov (United States)

    Cooney, David O.

    1987-01-01

    Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

  5. Adsorption of PTCDA on NaCl(100) and KCl(100)

    Science.gov (United States)

    Aldahhak, H.; Schmidt, W. G.; Rauls, E.

    2013-11-01

    The adsorption of PTCDA on KCl and NaCl(100) surfaces has been investigated by means of first principles calculations. Besides a variety of adsorbate structures for single molecules and a monolayer of flat lying molecules on plain terraces, the influence of monoatomic steps and the different defect site at step edges has been studied in detail.

  6. Expanded-bed adsorption utilizing ion-exchange resin to purify extracellular beta-galactosidase.

    Science.gov (United States)

    Pereira, J A; Vieira E Rosa, P De T; Pastore, G M; Santana, C C

    1998-01-01

    The application of expanded-bed ion-exchange resins allows the elimination of intermediary particulate separation steps like filtration or centrifugation prior to adsorption steps in enzyme-purification processes from crude fermentation broths. This work is concerned with the experimental evaluation data of a process related to the adsorption of an extracellular p-galactosidase from the fungi Scopulariopsis. The protein recovery in the ion-exchange resin Accell Plus QMA was accomplished using a continuous-monitoring method. The direct adsorption step was followed by a elution step with concentrated NaCl solutions aiming to improve the enzyme-specific activity. Experimental data for fixed and expanded bed were compared.

  7. Adsorption of reactive brilliant red K-2BP on activated carbon developed from sewage sludge

    Institute of Scientific and Technical Information of China (English)

    Jiankun XIE; Qinyan YUE; Hui YU; Wenwen YUE; Renbo LI; Shengxiao ZHANG; Xiaona WANG

    2008-01-01

    Activated carbon was prepared from the sewage sludge of municipal wastewater treatment plant by chemical activation (activation reagent is ZnCl2) and was used for the adsorption of dye (reactive brilliant red K-2BP). The impact of adsorbent amount, adsorption time and pH value on adsorption effect, the adsorption kinetics, and the adsorption thermodynamics were dis-cussed according to batch adsorption tests. The results indicated that the activated carbon developed from sewage sludge (ACSS), which was mesoporous, possessed opened porous structures. The iodine number of the ACSS was heavy metals in the leachate didn't exceed the contents limit. The adsorption kinetics of reactive brilliant red K-2BP on the ACSS was accorded with the two-step kinetics rate equation and pseudo-second-order kinetics equation. Compared to the Freundlich isotherm equation, the Langmuir isotherm equation showed better applicability for the adsorption. The adsorption which was favorable was an endothermic (enthalpy △H > 0) and spontaneous (flee energy △G 0).

  8. [Removal of Sulfate Ions from Aqueous Solution by Adsorption with Hydrotalcite- like Composite].

    Science.gov (United States)

    Gu, Yi-bing; Ma, Yong-wen; Wan, Jin-quan; Wang, Yan; Guan, Ze-yu

    2016-03-15

    Hydrotalcite-like composite synthesized by co-precipitation method was used as an adsorbent to remove the sulfate ions in aqueous solution. XRD, FT-IR , SEM and EDS elemental analysis were used to clarify the structure and composition of the hydrotalcite- like composite. The influences of time, initial pH value and coexisting ions on adsorption performance were investigated. The result showed the material was the composite of zinc aluminum nitrate hydrotalcite-like compounds and zinc aluminum phenylalanine hydrotalcite-like compounds. Hydrotalcite-like composite had a good performance in adsorption of sulfate ions, and the maximum adsorption capacity was 52.75 mg · g⁻¹. The data fitted pseudo-second order kinetic model best, which indicated that chemical adsorption was the rate-limiting step. Freundlich isotherm was more suitable to describe the adsorption process, and this meant the adsorption of sulfate ions by hydrotalcite-like composite was multilayered adsorption. Thermodynamic parameters showed that the adsorption process was endothermic and spontaneous at room temperature. Hydrotalcite-like composite adsorbed sulfate ions mainly through ion exchange, electrostatic force and physical adsorption. The experimental results showed that the hydrotalcite-like composite had potential for sulfate ion removal in the aqueous solution.

  9. Characteristic Evaluation of Graphene Oxide for Bisphenol A Adsorption in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Thatchaphong Phatthanakittiphong

    2016-07-01

    Full Text Available This paper investigates the characteristics of graphene oxide (GO for Bisphenol A (BPA adsorption in water. Batch experiments on the influence of significant parameters were performed. While an improvement of the adsorption capacity of BPA was obtained by the increment of contact time and the initial BPA concentration, the increment of pH above 8, GO dosage, and temperature showed the reverse results. The thermodynamic study suggested that BPA adsorption on GO was an exothermic and spontaneous process. The kinetics was explained by the pseudo-second-order model which covers all steps of adsorption. The fit of the results with the Langmuir isotherm indicated the monolayer adsorption. At 298 K, the adsorption reached equilibrium within 30 min with the maximum adsorption capacity of 49.26 mg/g. The low BPA adsorption capacity of GO can be interpreted by the occurrence of oxygen-containing functional groups (OCFGs that are able to form hydrogen bonds with the surrounding OCFGs and water molecules. This effect inhibited the role of π–π interactions that are mainly responsible for the adsorption of BPA.

  10. Facile synthesis of boehmite/PVA composite membrane with enhanced adsorption performance towards Cr(VI).

    Science.gov (United States)

    Luo, Lei; Cai, Weiquan; Zhou, Jiabin; Li, Yuanzhi

    2016-11-15

    A novel boehmite/PVA composite membrane (BPCM) with remarkably enhanced adsorption performance towards Cr(VI) was successfully synthesized from Al(NO3)3·9H2O using HAc as the peptizing agent via a facile sol-gel method. The physicochemical properties of the BPCM, the boehmite powder (BP) without PVA and a commercial boehmite powder (CBP) were comparatively characterized by XRD, TGA-DSC, FT-IR and XPS. Batch adsorption experiments showed that the adsorption performance of the BPCM is much better than those of BP and CBP. Its adsorption process was well described by the pseudo-second-order kinetic model, and its equilibrium data fit the Langmuir isotherm well with a maximum adsorption capacity of 36.41mgg(-1). Its interference adsorption experiment in presence of coexisting anions showed that SO4(2-) and HPO4(2-) have greater effect than those of the Cl(-), F(-), C2O4(2-) and HCO3(-). A three step action mechanism including adsorption of Cr(VI) anions, complexation between Cr(VI) anions and the functional groups on the surface of BPCM, and the reduction of Cr(VI) to Cr(III) was proposed to illustrate the adsorption process. This efficient film could be easily separated after adsorption, exhibiting great potential for the removal of Cr(VI) from aqueous solution, and other fields of environmental remediation. PMID:27450337

  11. Experimental study on dynamic gas adsorption

    Institute of Scientific and Technical Information of China (English)

    Qin Yueping; Wang Yaru; Yang Xiaobin; Liu Wei; Luo Wei

    2012-01-01

    In order to predict the actual adsorption amount as gas adsorption reaches the equilibrium,this research designed a dynamic gas adsorption experiment under constant temperature and pressure,and also studied the isopiestic adsorption characteristics of coal samples with same quality but different sizes.Through the experiment,the study found the adsorption-time changing relationships under different pressures of four different size samples.After regression analysis,we obtained the functional relationship between adsorption and time.According to this,the research resulted in the actual adsorption amount when gas adsorption reaches the equilibrium.In addition,the current study obtained the relationship between adsorption and pressure as well as the effect of the coal size to the adsorption rate.These results have great theoretical and practical significance for the prediction of gas amount in coal seam and gas adsorption process.

  12. Adsorption of Atenolol on Kaolinite

    Directory of Open Access Journals (Sweden)

    Yingmo Hu

    2015-01-01

    Full Text Available In this study the adsorption of atenolol (AT, a β-blocker, on kaolinite, a clay mineral of low surface charge, was investigated under varying initial AT concentration, equilibrium time, solution pH, ionic strength, and temperature conditions. The results showed that the amounts of AT uptake by kaolinite were close to its cation exchange capacity value and the AT adsorption was almost instantaneous, suggesting a surface adsorption. The adsorption was exothermic and the free energy of adsorption was small negative, indicating physical adsorption. The increase in ionic strength of the solution drastically reduced AT uptake on kaolinite. A significant reduction in AT uptake was found at solution pH below 5 or above 10. The FTIR results showed band shifting and disappearance for NH bending vibration and benzene ring skeletal vibration at 3360 and 1515 cm−1 and band splitting at 1412 and 1240 cm−1 attributed to C–N valence vibration coupled with NH bending vibrations and alkyl aryl ether linkage, suggesting the participation of NH, –O–, and benzene ring for AT adsorption on kaolinite.

  13. Adsorption Desalination: A Novel Method

    KAUST Repository

    Ng, Kim Choon

    2010-11-15

    The search for potable water for quenching global thirst remains a pressing concern throughout many regions of the world. The demand for new and sustainable sources and the associated technologies for producing fresh water are intrinsically linked to the solving of potable water availability and hitherto, innovative and energy efficient desalination methods seems to be the practical solutions. Quenching global thirst by adsorption desalination is a practical and inexpensive method of desalinating the saline and brackish water to produce fresh water for agriculture irrigation, industrial, and building applications. This chapter provides a general overview of the adsorption fundamentals in terms of adsorption isotherms, kinetics, and heat of adsorption. It is then being more focused on the principles of thermally driven adsorption desalination methods. The recent developments of adsorption desalination plants and the effect of operating conditions on the system performance in terms of specific daily water production and performance ratio are presented. Design of a large commercial adsorption desalination plant is also discussed herein.

  14. The corrosive influence of chloride ions preference adsorption on α-Al2O3 (0 0 0 1) surface

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The preference adsorption and interaction of Cl− at increasing monolayer coverage on Al2O3 in solution environment are modeling by DFT with COSMO. • A redefinition critical one plane monolayer of Cl− is 3/7, and the adsorption energy decrease in three steps, each adsorption energy step only relate to the adsorption site and the morphology. • The weaker interaction between Cl− and Al2O3 surface but stronger interactions between three Cl− make the electrons uniformly occupy on the energy levels of three ions. - Abstract: Conductor-like screening model (COSMO), Periodic DFT calculations have been performed on a Al2O3 surface to model the influence of preference adsorption and interaction of chloride ions at increasing monolayer coverage on undefective passive film on Aluminum in solution environment. The results evidence that the critical monolayer of Cl− is 3/7, which is redefined. With increasing Cl− adsorption, both the first and second Cl− move from Al(1) atop and bridge10 sites to O(5) sites, suggesting that the weaker interaction between Cl− and Al2O3 surface but stronger interactions between three ions make the electrons uniformly occupy on the energy levels of them. More calculations shows that the preference adsorption sites of Cl− are independent of the surface area of oxide, and the adsorption energy decrease in three steps, each adsorption energy step only relate to the adsorption site and the morphology. On undefective oxide film, low coverage Cl− adsorption would restrain surface breakdown to happen which is consistent with the experiment results

  15. Carbide induced reconstruction of monatomic steps on Ni(111) - A density functional study

    DEFF Research Database (Denmark)

    Andersson, Martin; Abild-Pedersen, Frank

    2007-01-01

    sites at the step-edge. It is furthermore possible to extend the carbide with the clock reconstructed geometry onto the upper terrace with a net energy gain compared to adsorption of carbon on unreconstructed close-packed steps or terrace sites on Ni(111). Our findings explain the fact that carbide...

  16. Carbon nanomaterials for gas adsorption

    CERN Document Server

    Terranova, Maria Letizia

    2012-01-01

    Research in adsorption of gases by carbon nanomaterials has experienced considerable growth in recent years, with increasing interest for practical applications. Many research groups are now producing or using such materials for gas adsorption, storage, purification, and sensing. This book provides a selected overview of some of the most interesting scientific results regarding the outstanding properties of carbon nanomaterials for gas adsorption and of interest both for basic research and technological applications. Topics receiving special attention in this book include storage of H, purific

  17. Implementasi Sistem Step By Step Switching Menggunakan Komponen Terintegrasi

    OpenAIRE

    Suherman

    2009-01-01

    Sentral yang menggunakan sistem step by step switching telah lama ditinggalkan. Teknologi telah beralih ke sistem switching digital common control, bahkan berbasis packet switching khususnya penggunaan IP based Network. Namun demikian, teknologi switching step by step yang dahulu berbasis sistem mekanis masih dapat diperbaharui dengan memanfaatkan komponen terintegrasi (integrates cicuit, IC). Sistem switching step by step dengan komponen terintegrasi ini dapat dimanfaatkan untuk membentuk...

  18. Kinetically controlled growth of gallium on stepped Si (553) surface

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mukesh; Pasha, Syed Khalid; Govind,, E-mail: govind@nplindia.org

    2013-10-15

    Kinetically controlled growth of gallium (Ga) metal has been reported on high index stepped Si (553) surface and its thermal stability with various novel superstructural phases has been analyzed. Auger electron spectroscopy studies revealed that the adsorption of Ga at room temperature (RT) follows Frank–van der Merwe (FM) growth mode while for higher substrate temperature, Ga adsorption remains within the submonolayer range. Thermal desorption and low energy electron diffraction studies investigated the formation of thermally stable Ga-islands and the various Ga induced superstructural phase on Si (553). During room temperature adsorption, (1 1 1)7 × 7 facet of Si (553) reconstructed into (1 1 1)6 × 6 facet while during desorption process, stable (1 1 1)6 × 6 and (1 1 1)√3 × √3-R30° surface reconstructions has been observed.

  19. Kinetically controlled growth of gallium on stepped Si (553) surface

    Science.gov (United States)

    Kumar, Mukesh; Pasha, Syed Khalid; Govind

    2013-10-01

    Kinetically controlled growth of gallium (Ga) metal has been reported on high index stepped Si (553) surface and its thermal stability with various novel superstructural phases has been analyzed. Auger electron spectroscopy studies revealed that the adsorption of Ga at room temperature (RT) follows Frank-van der Merwe (FM) growth mode while for higher substrate temperature, Ga adsorption remains within the submonolayer range. Thermal desorption and low energy electron diffraction studies investigated the formation of thermally stable Ga-islands and the various Ga induced superstructural phase on Si (553). During room temperature adsorption, (1 1 1)7 × 7 facet of Si (553) reconstructed into (1 1 1)6 × 6 facet while during desorption process, stable (1 1 1)6 × 6 and (1 1 1)√3 × √3-R30° surface reconstructions has been observed.

  20. Equilibrium models and kinetic for the adsorption of methylene blue on Co-hectorites

    International Nuclear Information System (INIS)

    The adsorption of methylene blue (MB) onto the surface of cobalt doping hectorite (Co-hectorite) was systematically studied. The physical properties of Co-hectorites were investigated, where characterizations were carried out by X-ray diffraction (XRD) and Electron Diffraction Spectrum (EDS) techniques, and morphology was examined by nitrogen adsorption. The sample with a Co content 5% (m/m) had a higher specific surface area than other Co-hectorites. The pore diameters were distributed between 2.5 and 5.0 nm. The adsorption results revealed that Co-hectorite surfaces possessed effective interactions with MB and bases, and greatest adsorption capacity achieved with Co content 5%, where the best-fit isotherm model was the Langmuir adsorption model. Kinetic studies were fitted to the pseudo-second-order kinetic model. The intraparticle diffusion was not the rate-limiting step for the whole reaction.

  1. Selective adsorption of L- and D-amino acids on calcite: Implications for biochemical homochirality

    Science.gov (United States)

    Hazen, R. M.; Filley, T. R.; Goodfriend, G. A.

    2001-01-01

    The emergence of biochemical homochirality was a key step in the origin of life, yet prebiotic mechanisms for chiral separation are not well constrained. Here we demonstrate a geochemically plausible scenario for chiral separation of amino acids by adsorption on mineral surfaces. Crystals of the common rock-forming mineral calcite (CaCO(3)), when immersed in a racemic aspartic acid solution, display significant adsorption and chiral selectivity of d- and l-enantiomers on pairs of mirror-related crystal-growth surfaces. This selective adsorption is greater on crystals with terraced surface textures, which indicates that d- and l-aspartic acid concentrate along step-like linear growth features. Thus, selective adsorption of linear arrays of d- and l-amino acids on calcite, with subsequent condensation polymerization, represents a plausible geochemical mechanism for the production of homochiral polypeptides on the prebiotic Earth.

  2. Study of Hydrogen Adsorption on Pt/WO3-ZrO2 through Pt Sites

    Institute of Scientific and Technical Information of China (English)

    Sugeng Triwahyono; Aishah Abdul Jalil; Hideshi Hattori

    2007-01-01

    The rate determining step and the energy barrier involved in hydrogen adsorption on Pt/WO3ZrO2 were studied based on the assumption that the hydrogen adsorption occurs only through Pt sites.The rate of hydrogen adsorption on Pt/WO3-ZrO2 Was measured in the adsorption temperature range of 323-573 K and an initial hydrogen pressure of 50 Torr.The rates of hydrogen uptake were very high for the initial few minutes and the adsorption continued for more than 5 h below 523 K.The hydrogen uptake far exceeded the H/Pt ratio of unity for all adsorption temperatures,indicating that the adsorption of hydrogen involved the dissociative adsorption of hydrogen on Pt sites to form hydrogen atoms.the spillover of hydrogen atoms onto the surface of the WO3-ZrO2 catalyst.the diffusion of spiltover hydrogen atom over the surface of the WO3-ZrO2 catalyst,and the formation of protonic acid site originated from hydrogen atom by releasing an electron in which the electron may react with a second hydrogen atom to form a hydride near the Lewis acid site.The rate determining step was the spillover with the activation energy of 12.3 kJ/mol.The rate of hydrogen adsorption cannot be expressed by the rate equation based on the assumption that the rate determining step is the surface diffusion.The activity of Pt/WO3-ZrO2 Was examined on n-heptane isomerization in which the increase of hydrogen partial pressure provided positive-effect on the conversion of n-heptane and negative-effect on the selectivity towards iso-heptane.

  3. Partial oxidation of Step-Bound Water Leads to Anomalous pH Effects on Metal Electrode Step-Edges

    CERN Document Server

    Schwarz, Kathleen; Yan, Yushan; Sundararaman, Ravishankar

    2016-01-01

    The design of better heterogeneous catalysts for applications such as fuel cells and electrolyzers requires a mechanistic understanding of electrocatalytic reactions and the dependence of their activity on operating conditions such as pH. A satisfactory explanation for the unexpected pH dependence of electrochemical properties of platinum surfaces has so far remained elusive, with previous explanations resorting to complex co-adsorption of multiple species and resulting in limited predictive power. This knowledge gap suggests that the fundamental properties of these catalysts are not yet understood, limiting systematic improvement. Here, we analyze the change in charge and free energies upon adsorption using density-functional theory (DFT) to establish that water adsorbs on platinum step edges across a wide voltage range, including the double-layer region, with a loss of approximately 0.2 electrons upon adsorption. We show how the change in net surface charge due to this water explains the anomalous pH variat...

  4. Cryogenic Adsorption of Low-concentration Hydrogen on 5A Molecular Sieve Bed

    Institute of Scientific and Technical Information of China (English)

    LIU; Zhen-xing; YANG; Hong-guang; XIA; Ti-rui; ZHAN; Qin; YANG; Li-ling

    2013-01-01

    The separation of low-concentration hydrogen isotopes from helium is a processing step that is required for ceramic lithium breeding blanket processing.In this study,the adsorption of low-concentration hydrogen from helium carrier was measured using 5A molecular sieve fixed bed in the cryogenic condition.The adsorption performances of hydrogen on 5A molecular sieve were discussed.The effect of the different

  5. What Governs Protein Adsorption and Immobilization at a Charged Solid Surface?

    OpenAIRE

    Kubiak-Ossowska, Karina; Mulheran, Paul A.

    2010-01-01

    The adsorption of hen egg white lysozyme at a model charged surface is studied using fully atomistic molecular dynamics simulations. The simulations are performed over a 90 ns time scale which is sufficient to observe rotational and translational steps in the adsorption process. Electrostatics is found to play a key role in guiding the protein to the favorable binding orientation with the N,C-terminal face against the substrate. However, full immobilization appears to only occur through the s...

  6. Potential Theory of Multicomponent Adsorption

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1998-01-01

    We developed a theory of multicomponent adsorption on the basis of the potential concept originally suggested by Polanyi. The mixture is considered as a heterogeneous substance segregated in the external field emitted by the adsorbent. The same standard equation of state, with no additional fitting...... parameters, is used for the segregated and for the bulk phases. With this approach, few parameters are needed to correlate pure component adsorption isotherms. These parameters may be used to predict adsorption equilibria of multicomponent mixtures without additional adjustment. A connection between...... the potential theory and the spreading pressure concept is established, and problems of the theory consistency are studied. Numerical algorithms are suggested for evaluation of the segregated state of the mixture in the potential field of adsorption forces. Comparison with experimental data shows good agreement...

  7. Prediction of Pure Component Adsorption Equilibria Using an Adsorption Isotherm Equation Based on Vacancy Solution Theory

    DEFF Research Database (Denmark)

    Marcussen, Lis; Aasberg-Petersen, K.; Krøll, Annette Elisabeth

    2000-01-01

    An adsorption isotherm equation for nonideal pure component adsorption based on vacancy solution theory and the Non-Random-Two-Liquid (NRTL) equation is found to be useful for predicting pure component adsorption equilibria at a variety of conditions. The isotherm equation is evaluated successfully...... adsorption systems, spreading pressure and isosteric heat of adsorption are also calculated....

  8. Molecular adsorption on graphene

    Science.gov (United States)

    Kong, Lingmei; Enders, Axel; Rahman, Talat S.; Dowben, Peter A.

    2014-11-01

    Current studies addressing the engineering of charge carrier concentration and the electronic band gap in epitaxial graphene using molecular adsorbates are reviewed. The focus here is on interactions between the graphene surface and the adsorbed molecules, including small gas molecules (H2O, H2, O2, CO, NO2, NO, and NH3), aromatic, and non-aromatic molecules (F4-TCNQ, PTCDA, TPA, Na-NH2, An-CH3, An-Br, Poly (ethylene imine) (PEI), and diazonium salts), and various biomolecules such as peptides, DNA fragments, and other derivatives. This is followed by a discussion on graphene-based gas sensor concepts. In reviewing the studies of the effects of molecular adsorption on graphene, it is evident that the strong manipulation of graphene’s electronic structure, including p- and n-doping, is not only possible with molecular adsorbates, but that this approach appears to be superior compared to these exploiting edge effects, local defects, or strain. However, graphene-based gas sensors, albeit feasible because huge adsorbate-induced variations in the relative conductivity are possible, generally suffer from the lack of chemical selectivity.

  9. Protein Adsorption in Three Dimensions

    OpenAIRE

    Vogler, Erwin A.

    2011-01-01

    Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the...

  10. Amphiphile Adsorption on Rigid Polyelectrolytes

    OpenAIRE

    Kuhn, Paulo S.; Levin, Yan; Barbosa, Marcia C.; Ravazzolo, Ana Paula

    2007-01-01

    A theory is presented which quantitatively accounts for the cooperative adsorption of cationic surfactants to anionic polyelectrolytes. For high salt concentration we find that the critical adsorption concentration (CAC) is a bilinear function of the polyion monomer and salt concentrations, with the coefficients dependent only on the type of surfactant used. The results presented in the paper might be useful for designing more efficient gene delivery systems.

  11. Scaling properties of adsorption energies for hydrogen-containing molecules on transition-metal surfaces

    DEFF Research Database (Denmark)

    Abild-Pedersen, Frank; Greeley, Jeffrey Philip; Studt, Felix;

    2007-01-01

    Density functional theory calculations are presented for CHx, x=0,1,2,3, NHx, x=0,1,2, OHx, x=0,1, and SHx, x=0,1 adsorption on a range of close-packed and stepped transition-metal surfaces. We find that the adsorption energy of any of the molecules considered scales approximately with the adsorp...... adsorption energy of the central, C, N, O, or S atom, the scaling constant depending only on x. A model is proposed to understand this behavior. The scaling model is developed into a general framework for estimating the reaction energies for hydrogenation and dehydrogenation reactions....

  12. ADSORPTION OF POLYCHLORINATED BIPHENYLS BY SOILS

    OpenAIRE

    Mihaela Preda; Radu Lăcătuşu; Dumitru Marian Motelică; Nicoleta Vrînceanu; Veronica Tănase

    2010-01-01

    The behavior of polychlorinated biphenyls (PCBs) in soil is determined by several factors including adsorption, mobility and degradation. Adsorption, directly or indirectly, influences the other factors. Adsorption process is generally evaluated by using adsorption isotherms representing the relationship between the quantity of substance adsorbed per unit weight and concentration of the substance in solution at equilibrium. They allow determination of the adsorption constant, which is directl...

  13. Adsorption refrigeration technology theory and application

    CERN Document Server

    Wang, Ruzhu; Wu, Jingyi

    2014-01-01

    Gives readers a detailed understanding of adsorption refrigeration technology, with a focus on practical applications and environmental concerns Systematically covering the technology of adsorption refrigeration, this book provides readers with a technical understanding of the topic as well as detailed information on the state-of-the-art from leading researchers in the field. Introducing readers to background on the development of adsorption refrigeration, the authors also cover the development of adsorbents, various thermodynamic theories, the design of adsorption systems and adsorption refri

  14. Modeling of Experimental Adsorption Isotherm Data

    OpenAIRE

    Xunjun Chen

    2015-01-01

    Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained...

  15. Effect of Humic Acid on As Redox Transformation and Kinetic Adsorption onto Iron Oxide Based Adsorbent (IBA

    Directory of Open Access Journals (Sweden)

    Hoda Fakour

    2014-10-01

    Full Text Available Due to the importance of adsorption kinetics and redox transformation of arsenic (As during the adsorption process, the present study elucidated natural organic matter (NOM effects on As adsorption-desorption kinetics and speciation transformation. The experimental procedures were conducted by examining interactions of arsenate and arsenite with different concentrations of humic acid (HA as a model representative of NOM, in the presence of iron oxide based adsorbent (IBA, as a model solid surface in three environmentally relevant conditions, including the simultaneous adsorption of both As and HA onto IBA, HA adsorption onto As-presorbed IBA, and As adsorption onto HA-presorbed IBA. Experimental adsorption-desorption data were all fitted by original and modified Lagergren pseudo-first and -second order adsorption kinetic models, respectively. Weber’s intraparticle diffusion was also used to gain insight into the mechanisms and rate controlling steps, which the results suggested that intraparticle diffusion of As species onto IBA is the main rate-controlling step. Different concentrations of HA mediated the redox transformation of As species, with a higher oxidation ability than reduction. The overall results indicated the significant effect of organic matter on the adsorption kinetics and redox transformation of As species, and consequently, the fate, transport and mobility of As in different environmentally relevant conditions.

  16. Single-step synthesis of magnetic chitosan composites and application for chromate (Cr(VI)) removal

    Institute of Scientific and Technical Information of China (English)

    杨卫春; 唐琼芝; 董舒宇; 柴立元; 王海鹰

    2016-01-01

    Magnetic chitosan composites (Fe3O4@chitosan) were synthesized in one single-step, characterized and applied in Cr(VI) removal from water. With the increase of loading proportion of chitosan, Cr(VI) adsorption capacity of Fe3O4@chitosan composites increased from 10.771 to 21.040 mg/g. The optimum adsorption capacities of Cr(VI) on Fe3O4@chitosan-3 were found in a pH range of 3.0−5.0. Kinetic study results show that the adsorption process follows pseudo-second-order model, indicating that the rate-limiting step in the adsorption of Cr(VI) involves chemisorptions. Moreover, FT-IR spectra analysis confirms that the amine and hydroxyl groups of chitosan are predominantly responsible for binding. Results from this work demonstrate that the prepared Fe3O4@chitosan composites possess great potential in Cr(VI) removal from contaminated water.

  17. Adsorption of lanthanum to goethite in the presence of gluconate

    Energy Technology Data Exchange (ETDEWEB)

    Hull, Laurence C.; Sarah Pepper; Sue Clark

    2005-05-01

    Adsorption of Lanthanum to Goethite in the Presence of Gluconic Acid L. C. HULL,1 S. E. PEPPER2 AND S. B. CLARK2 1Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (hulllc@inel.gov) 2Washington State University, Pullman, WA (spepper@wsu.edu), (s_clark@wsu.edu) Lanthanide and trivalent-actinide elements in radioactive waste can pose risks to humans and ecological systems for many years. Organic complexing agents, from natural organic matter or the degradation of waste package components, can alter the mobility of these elements. We studied the effect of gluconic acid, as an analogue for cellulose degradation products, on the adsorption of lanthanum, representing lanthanide and trivalent-actinide elments, to goethite, representing natural iron minearals and degradation products of waste packages. Batch pH adsorption edge experiments were conducted with lanthanum alone, and with lanthanum and gluconate at a 1:1 mole ratio. Lanthanum concentrations studied were 0.1, 1, and 10 mM, covering a range from 10% to 1000% of the calculated available adsorption sites on goethite. In the absence of gluconate, lanthanum was primarily present in solution as free lanthanum ion. With gluconate present, free lanthanum concentration in solution decreased with increasing pH as step-wise deprotonation of the gluconate molecule increased the fraction lanthanum complexed with gluconate. Adsorption to the goethite surface was represented with the diffuse double-layer model. The number of adsorption sites and the intrinsic binding constants for the surface complexes were estimated from the pH adsorption edge data using the computer code FITEQL 4.0. Two surface reactions were used to fit the adsorption data in the absence of gluconate. A strong binding site with no proton release and a much higher concentration of weak binding sites with release of two protons per lanthanum adsorbed. The adsorption of lanthanum was not measurably affected by the presence of gluconate

  18. Adsorption of carbon dioxide on amine-modified TiO2 nanotubes

    Institute of Scientific and Technical Information of China (English)

    Fujiao Song; Yunxia Zhao; Qin Zhong

    2013-01-01

    TiO2 nanotubes (TiNT) were prepared by a hydrothermal treatment and modified by three kinds of amines,namely ethylenediamine,polyetherimide and tetraethylenepentamine (TEPA),to study their CO2 adsorption properties from gas streams.The resultant samples were characterized by X-ray diffraction,transmission electron microscopy,and infrared spectroscopy,as well as low temperature N2adsorption.CO2 capture was investigated in a dynamic packed column at 30℃.TEPA-modified TiO2 nanotubes showed the highest adsorption capacity of 167.64 mg/g because it had the highest amino-group content among the three amines.CO2 fixation on TiNT impregnated by TEPA was investigated at 30,50,and 70℃C,and the adsorption capacity increased slightly with temperature.Following the adsorption step,the sorbents were regenerated by temperature programmed desorption,and the TiNT-TEPA sample,as CO2 sorbent,was found to be readily regenerated and energy-efficient.The cycle test also revealed that the TiNT-TEPA adsorbent is fairly stable,with only a 5% drop in the adsorption capacity after 10 adsorption/desorption cycles.In addition,the CO2 adsorption behavior was investigated with the deactivation model,and which showed an excellent prediction for the TiNT-TEPA breakthrough curves.

  19. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon.

    Science.gov (United States)

    Yu, Jing; Lv, Lu; Lan, Pei; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming

    2012-07-30

    Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (30kDa) had much less effect on PFC adsorption capacity. PMID:22609392

  20. Thermodynamic Profile of Some Heavy Metal Ions Adsorption Onto Biomaterial Surfaces

    Directory of Open Access Journals (Sweden)

    Medhat A. Shaker

    2007-01-01

    Full Text Available The adsorption of Co2+, Zn2+, Pb2+ and Hg2+ onto dried non-living biomass (NB of different Pseudomonas strains has been investigated in detail. Maximum adsorption of these cations is achieved at optimum pH values from 3.5 to 4.5 to avoid hydrolysis, polymerization and precipitation of metal cations in the treatment solutions. The experimental data obtained at different temperatures were fitted to the Langmuir model at different temperatures from 283 to 323 K. Metal ions adsorption occurs in multi detectable steps (i=A, B, C. Binding of Pb(II to NB occurs in one detectable step labeled A, where two detectable binding steps were observed for the other cations; A and B for Zn(II, A and C for Co(II, B and C for Hg(II, respectively. Site capacities, υi are found to be temperature-independent in the whole investigated temperature range. The thermodynamic parameters (∆Hi, ∆Si and ∆Gi for the adsorption processes were calculated for each binding step i and the results suggest that the nature of adsorption is endothermic and the process is spontaneous and favorable. Thermodynamic data pairs (∆Hi , ∆Si for metal binding are linearly correlated for all sites in the investigated biosorption systems.

  1. The adsorption and mass-transfer process of cationic red X-GRL dye on natural zeolite.

    Science.gov (United States)

    Tian, Jingjing; Guan, Junfang; Gao, Huimin; Wen, Yafei; Ren, Zijie

    2016-01-01

    The adsorption behavior of natural zeolite was studied in order to determine the adsorption capacity and mass-transfer process of cationic red X-GRL (C(18)H(21)BrN(6)) onto the adsorbent. The adsorption tests to determine both the uptake capacity and the mass-transfer process at equilibrium were performed under batch conditions, which showed rapid uptake in general for the initial 5 min, corresponding to 92% total removal. The equilibrium adsorption capacity value (q(e,cal)) in pseudo-second-order kinetics was 13.51 mg/g at 293 K and the whole adsorption process was governed by physical adsorption with an endothermic, endothermic spontaneous nature. Adsorption tests indicated that the zeolite has great potential as an alternative low-cost material in the treatment of X-GRL drainage. However, the mass-transfer process to determine the rate-controlling steps showed that both film diffusion and pore diffusion were important in controlling the adsorption rate. The adsorption process was governed by film diffusion while pore diffusion was poor because the X-GRL molecules could not penetrate into the zeolite easily. The X-GRL molecules were only adsorbed on the external surface of the zeolite. Hence, to improve the adsorption capacity of natural zeolite further, modification to expand its micropores is necessary.

  2. Learning SQL in Steps

    Directory of Open Access Journals (Sweden)

    Philip Garner

    2015-08-01

    Full Text Available Learning SQL is a common problem for many Computer Science (CS students, the steps involved are quite different to those mastered when learning procedural or object-oriented programming languages. The introduction of commercial products that include shortcuts into the learning environment can initially appear to benefit the student, however, transferring these skills to a textual environment can be difficult for many students. Computer Science students are required to build textual SQL queries because the demands of complex queries can quickly out grow the capabilities of graphical query builders available in many software packages. SQL in Steps (SiS is a graphical user interface centred around the textual translation of a query; this combination of a GUI and a clear representation of its textual meaning has the potential to improve the way in which users gain an understanding of SQL. SiS allows for an incremental and evolutionary development of queries by enabling students to build queries step by step until their goal is reached. A planned evaluation of SiS hopes to quantify the extent to which the introduction of such a user interface into the learning environment can improve the students' understanding of the language.

  3. Step-Change

    NARCIS (Netherlands)

    Babah Daouda, Falylath; Ingenbleek, P.T.M.; Trijp, van H.C.M.

    2016-01-01

    With upcoming middle classes in Africa, micro-entrepreneurs witness new opportunities that can potentially lift them out of poverty. Exploiting these opportunities requires entrepreneurs to make a ‘step-change’ away from the bottom of the pyramid to middle-class markets. This process hosts potent

  4. A Major Step Forward

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Optimism arises from the new timetable of denuclearization of the Korean Peninsula Chinese officials like to use mountain climbing to describe the six-party talks aimed at resolving the North Korean nuclear puzzle.In this sense,any step toward the peak-"the verifiable denuclearization of the Korean Peninsula in a peaceful manner"-

  5. A biological oil adsorption filter

    Energy Technology Data Exchange (ETDEWEB)

    Pasila, A. [University of Helsinki (Finland). Dept. of Agricultural Engineering and Household Technology

    2005-12-01

    A new oil adsorption method called adsorption filtration (AF) has been developed. It is a technology where by oil residues can be cleaned from water by running it through a simple filter made from freeze treated, dried, milled and then fragmented plant material. By choosing suitable plants and fragmentation sizes it is possible to produce filters, which pass water but adsorb oil. The aim of this study was to investigate the possibilities of manufacturing oil adsorbing filter materials from reed canary grass (Phalaris arundinacea), flax (Linum usitatissimum L.) or hemp fibre (Cannabis sativa L.). The oil (80 ml) was mixed with de-ionised water (200 ml) and this mixture was filtered through 10 or 20 g adsorption filters. Fine spring harvested hemp fibre (diameter less than 1 mm) and reed canary grass fragments adsorb 2-4 g of oil per gram of adsorption material compared to 1-3 g of water. Adsorption filtration is thus a novel way of gathering spilled oil in shallow coastal waters before the oil reaches the shore. (author)

  6. Steps and cycles

    OpenAIRE

    Chadwick, Andy

    2015-01-01

    Andy Chadwick* explains how interaction between continuous trend with natural climate cycles produces the observed stepped pattern of global warming Climate-change ‘sceptics’ have made great mileage out of the current hiatus in observed global warming. Atmospheric temperatures have not really increased since the turn of the 21st Century, a fact frequently cited as incompatible with, or even disproving, global warming. These same commentators draw a discreet veil over the fact that temper...

  7. Thermodynamical and structural insights of orange II adsorption by MgRAlNO3 layered double hydroxides

    International Nuclear Information System (INIS)

    [Mg1-x Alx(OH)2][(NO3)x, nH2O] Layered Double Hydroxide (LDH) sorbents with variable Mg/Al molar (R=(1-x)/x) ratios were investigated for adsorption of azo dye, orange II (OII) at various pH and temperature conditions. Mg2AlNO3 displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg2AlNO3 at 40 oC. Adsorption isotherms have been fitted using the Langmuir model and free energy of adsorption (ΔGo), enthalpy (ΔHo) and entropy (ΔSo) were calculated. The experimental values for ΔGo in temperature range between 10 and 40 oC were found to be negative indicating that a spontaneous process occurred. Positive calculated enthalpy values, characteristic of an endothermic process were found. Characterization of solids (PXRD, FTIR, UV-vis, TGA/DTA, adsorption isotherm BET analysis, SEM and Zetametry) before and after adsorption showed that adsorption proceeds in two steps. First, adsorption occurs at the LDH surface, followed by intercalation via anion exchange. -- Graphical Abstract: Structural and thermodynamical insight of adsorption/Intercalation of OII in MgRAl LDH Display Omitted Highlights: → The nitrate containing hydrotalcite-like compounds (MgRAlNO3 LDH) were prepared by the coprecipitation method. → Adsorption of anionic orange dye(OII) is studied on LDHs at different temperatures. → The adsorption process is well described by the Langmuir isotherm model. → Mg2AlNO3 displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg2AlNO3 at 40 oC. → Adsorption process does not occur on the surface of the LDH only but an intercalation process is also occurring concomitantly according to the thermodynamical values.

  8. Monomer Adsorption-Desorption Processes

    Institute of Scientific and Technical Information of China (English)

    KE Jian-Hong; LIN Zhen-Quan; CHEN Xiao-Shuang

    2009-01-01

    We propose an adsorption-desorption model for a deposit growth system, in which the adsorption and desorption of particles coexist. By means of the generalized rate equation we investigate the cluster (island) size distribution in the dynamic equilibrium state. The results show that the evolution behaviour of the system depends crucially on the details of the rate kernels. The cluster size distribution can take the ecale-frse power-law form in some cases, while it grows exponentially with size in other cases.

  9. Theoretical insight of adsorption cooling

    KAUST Repository

    Chakraborty, Anutosh

    2011-06-03

    This letter proposes and presents a thermodynamic formulation to calculate the energetic performances of an adsorption cooler as a function of pore widths and volumes of solid adsorbents. The simulated results in terms of the coefficient of performance are validated with experimental data. It is found from the present analysis that the performance of an adsorption cooling device is influenced mainly by the physical characteristics of solid adsorbents, and the characteristics energy between the adsorbent-adsorbate systems. The present study confirms that there exists a special type of silicagel having optimal physical characteristics that allows us to obtain the best performance.

  10. Tick Removal: A Step-by-Step Guide (For Parents)

    Science.gov (United States)

    ... Story" 5 Things to Know About Zika & Pregnancy Tick Removal: A Step-by-Step Guide KidsHealth > For Parents > Tick Removal: A Step-by-Step Guide Print A ... isn't a freckle at all. It's a tick. What should you do? First, don't panic. ...

  11. Adsorption of Organics from Domestic Water Supplies.

    Science.gov (United States)

    McGuire, Michael J.; Suffet, Irwin H.

    1978-01-01

    This article discusses the current state of the art of organics removal by adsorption. Various theoretical explanations of the adsorption process are given, along with practical results from laboratory, pilot-scale, and full-scale applications. (CS)

  12. ADSORPTION MALACHITE GREEN ON NATURAL ZEOLITE

    Directory of Open Access Journals (Sweden)

    Eko Ariyanto

    2012-02-01

    Full Text Available A natural zeolite was employed as adsorbent for reducing of malachite green from aqueous solution. A batch system was applied to study the adsorption of malachite green in single system on natural zeolite. The adsorption studies indicate that malachite green in single component system follows the second-order kinetics and the adsorption is diffusion process with two stages for malachite green. Malachite green adsorption isotherm follows the Langmuir model.

  13. Adsorption theory for polydisperse polymers.

    NARCIS (Netherlands)

    Roefs, S.P.F.M.; Scheutjens, J.M.H.M.; Leermakers, F.A.M.

    1994-01-01

    Most polymers are polydisperse. We extend the self-consistent field polymer adsorption theory due to Scheutjens and Fleer to account for an arbitrary polymer molecular weight distribution with a cutoff chain length Nmax. In this paper, the treatment is restricted to homopolymers. For this case a ver

  14. Adsorption of Levofloxacin to Goethite

    NARCIS (Netherlands)

    Qin, Xiaopeng; Liu, Fei; Zhao, Long; Hou, Hong; Wang, Guangcai; Li, Fasheng; Weng, Liping

    2016-01-01

    Batch experiments were conducted to investigate the adsorption of a widely used fluoroquinolone antibiotic levofloxacin (LEV) to goethite and effects of nitrate, sulfate, small organic acids, and humic acid (HA). The concentrations of LEV and small organic acids in single systems or mixtures were

  15. Scaling Laws of Polyelectrolyte Adsorption

    OpenAIRE

    Borukhov, I.; Andelman, D.; Orland, H.

    1997-01-01

    Adsorption of charged polymers (polyelectrolytes) from a semi-dilute solution to a charged surface is investigated theoretically. We obtain simple scaling laws for (i) the amount of polymer adsorbed to the surface, Gamma, and (ii) the width of the adsorbed layer D, as function of the fractional charge per monomer p and the salt concentration c_b. For strongly charged polyelectrolytes (p

  16. Effect of aniline on cadmium adsorption by sulfanilic acid-grafted magnetic graphene oxide sheets.

    Science.gov (United States)

    Hu, Xin-jiang; Liu, Yun-guo; Zeng, Guang-ming; Wang, Hui; Hu, Xi; Chen, An-wei; Wang, Ya-qin; Guo, Yi-Mming; Li, Ting-ting; Zhou, Lu; Liu, Shao-heng; Zeng, Xiao-xia

    2014-07-15

    Cd(II) has posed severe health risks worldwide. To remove this contaminant from aqueous solution, the sulfanilic acid-grafted magnetic graphene oxide sheets (MGOs/SA) were prepared and characterized. The mutual effects of Cd(II) and aniline adsorption on MGOs/SA were studied. The effects of operating parameters such as pH, ionic strength, contact time and temperature on the Cd(II) enrichment, as well as the adsorption kinetics and isotherm were also investigated. The results demonstrated that MGOs/SA could effectively remove Cd(II) and aniline from the aqueous solution and the two adsorption processes were strongly dependent on solution pH. The Cd(II) adsorption was reduced by the presence of aniline at pH5.4. The presence of Cd(II) diminished the adsorption capacity for aniline at pH7.8. The decontamination of Cd(II) by MGOs/SA was influenced by ionic strength. Besides, the adsorption process could be well described by pseudo-second-order kinetic model. The intraparticle diffusion study revealed that the intraparticle diffusion was not the only rate-limiting step for the adsorption process. Moreover, the experimental data of isotherm followed the Freundlich isotherm model.

  17. Site-Specific Scaling Relations for Hydrocarbon Adsorption on Hexagonal Transition Metal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Montemore, Matthew M.; Medlin, James W.

    2013-10-03

    Screening a large number of surfaces for their catalytic performance remains a challenge, leading to the need for simple models to predict adsorption properties. To facilitate rapid prediction of hydrocarbon adsorption energies, scaling relations that allow for calculation of the adsorption energy of any intermediate attached to any symmetric site on any hexagonal metal surface through a carbon atom were developed. For input, these relations require only simple electronic properties of the surface and of the gas-phase reactant molecules. Determining adsorption energies consists of up to four steps: (i) calculating the adsorption energy of methyl in the top site using density functional theory or by simple relations based on the electronic structure of the surface; (ii) using modified versions of classical scaling relations to scale between methyl in the top site and C₁ species with more metal-surface bonds (i.e., C, CH, CH₂) in sites that complete adsorbate tetravalency; (iii) using gas-phase bond energies to predict adsorption energies of longer hydrocarbons (i.e., CR, CR₂, CR₃); and (iv) expressing energetic changes upon translation of hydrocarbons to various sites in terms of the number of agostic interactions and the change in the number of carbon-metal bonds. Combining all of these relations allows accurate scaling over a wide range of adsorbates and surfaces, resulting in efficient screening of catalytic surfaces and a clear elucidation of adsorption trends. The relations are used to explain trends in methane reforming, hydrocarbon chain growth, and propane dehydrogenation.

  18. Adsorption of zinc ions from water using zeolite/iron oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Fungaro, D.A.; Graciano, J.E.A. [Institute for Energy and Nuclear Research, Sao Paulo (Brazil)

    2007-07-01

    The adsorption characteristics of zeolites synthesized from fly ash were combined in a composite with the magnetic properties of iron oxides to produce adsorbents which were magnetic materials. Such zeolite/iron oxide magnetic composites were prepared with weight ratios of 3:1, 2:1 and 1:1. The experimental data for the equilibrium adsorption isotherms of Zn{sup 2+} ions onto the composites were modelled using the Freundlich and Langmuir equations. The presence of iron oxide had no significant effect on the adsorption capacities of the magnetic composites. The experimental data were also employed to determine the kinetic characteristics of the adsorption process. The adsorption of Zn{sup 2+} ions was found to follow pseudo-second-order type kinetics. Although intra-particle diffusion occurred in the adsorption processes, it could not be accepted as the primary rate-determining step. The evaluated thermodynamic parameters indicated that the adsorption of Zn{sup 2+} ions onto zeolite/iron composites was spontaneous and endothermic.

  19. Adsorption kinetics and equilibrium study of nitrogen species onto radiata pine (Pinus radiata) sawdust.

    Science.gov (United States)

    Harmayani, Kadek D; Faisal Anwar, A H M

    2016-01-01

    Nitrogen species (NH3-N, NO3-N, and NO2-N) are found as one of the major dissolved constituents in wastewater or stormwater runoff. In this research, laboratory experiments were conducted to remove these pollutants from the water environment using radiata pine (Pinus radiata) sawdust. A series of batch tests was conducted by varying initial concentration, dosage, particle size, pH, and contact time to check the removal performance. Test results confirmed the effectiveness of radiata pine sawdust for removing these contaminants from the aqueous phase (100% removal of NO3-N, and NO2-N; 55% removal of NH3-N). The adsorbent dosage and initial concentration showed a significantly greater effect on the removal process over pH or particle sizes. The optimum dosage for contaminant removal on a laboratory scale was found to be 12 g. Next, the adsorption kinetics were studied using intraparticle diffusion, liquid-film diffusion, and a pseudo-first order and pseudo-second order model. The adsorption of all species followed a pseudo-second order model but NO2-N adsorption followed both models. In addition, the kinetics of NO2-N adsorption showed two-step adsorption following intraparticle diffusion and liquid-film diffusion. The isotherm study showed that NO3-N and NO2-N adsorption fitted slightly better with the Freundlich model but that NH3-N adsorption followed both Freundlich and Langmuir models. PMID:27438245

  20. Effect of aniline on cadmium adsorption by sulfanilic acid-grafted magnetic graphene oxide sheets.

    Science.gov (United States)

    Hu, Xin-jiang; Liu, Yun-guo; Zeng, Guang-ming; Wang, Hui; Hu, Xi; Chen, An-wei; Wang, Ya-qin; Guo, Yi-Mming; Li, Ting-ting; Zhou, Lu; Liu, Shao-heng; Zeng, Xiao-xia

    2014-07-15

    Cd(II) has posed severe health risks worldwide. To remove this contaminant from aqueous solution, the sulfanilic acid-grafted magnetic graphene oxide sheets (MGOs/SA) were prepared and characterized. The mutual effects of Cd(II) and aniline adsorption on MGOs/SA were studied. The effects of operating parameters such as pH, ionic strength, contact time and temperature on the Cd(II) enrichment, as well as the adsorption kinetics and isotherm were also investigated. The results demonstrated that MGOs/SA could effectively remove Cd(II) and aniline from the aqueous solution and the two adsorption processes were strongly dependent on solution pH. The Cd(II) adsorption was reduced by the presence of aniline at pH5.4. The presence of Cd(II) diminished the adsorption capacity for aniline at pHadsorption at pH>7.8. The decontamination of Cd(II) by MGOs/SA was influenced by ionic strength. Besides, the adsorption process could be well described by pseudo-second-order kinetic model. The intraparticle diffusion study revealed that the intraparticle diffusion was not the only rate-limiting step for the adsorption process. Moreover, the experimental data of isotherm followed the Freundlich isotherm model. PMID:24863786

  1. Adsorption of Hg{sup 2+} from aqueous solution onto polyacrylamide/attapulgite

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yijiang, E-mail: cyjzhao@yahoo.com [Chemistry Department of Huaiyin Teachers College, Key Laboratory for Chemistry of Low-Dimensional Materials of Jiangsu Province, No. 111 Changjiang West Road, Huaian 223300, Jiangsu Province (China); Chen Yan [Chemistry Department of Huaiyin Teachers College, Key Laboratory for Chemistry of Low-Dimensional Materials of Jiangsu Province, No. 111 Changjiang West Road, Huaian 223300, Jiangsu Province (China); State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009, Jiangsu Province (China); Li Meisheng; Zhou Shouyong; Xue Ailian [Chemistry Department of Huaiyin Teachers College, Key Laboratory for Chemistry of Low-Dimensional Materials of Jiangsu Province, No. 111 Changjiang West Road, Huaian 223300, Jiangsu Province (China); Xing Weihong [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing 210009, Jiangsu Province (China)

    2009-11-15

    Polyacrylamide/attapulgite (PAM/ATP) was prepared by the solution polymerization of acrylamide (AM) onto {gamma}-methacryloxypropyl trimethoxy silane (KH-570)-modified attapulgite (ATP). PAM/ATP was characterized using Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of contact time, adsorbent dosage, and pH of the initial solution on the adsorption capacities for Hg{sup 2+} were investigated. The adsorption process was rapid; 88% of adsorption occurred within 5 min and equilibrium was achieved at around 40 min. The equilibrium data fitted the Langmuir sorption isotherms well, and the maximum adsorption capacity of Hg{sup 2+} onto PAM/ATP was found to be 192.5 mg g{sup -1}. The adsorption kinetics of PAM/ATP fitted a pseudo-second-order kinetic model. Our results suggest that chemisorption processes could be the rate-limiting steps in the process of Hg{sup 2+} adsorption. Hg{sup 2+} adsorbed onto PAM/ATP could be effectively desorbed in hot acetic acid solution, and the adsorption capacity of the regenerated adsorbents could still be maintained at 95% by the sixth cycle.

  2. Linux in easy steps

    CERN Document Server

    McGrath, Mike

    2011-01-01

    Linux is becoming more and more popular, but the installation can often be daunting for new users. Linux in Easy Steps to the rescue! Following this book's simple instructions, readers quickly install Linux, learn to explore the desktop, and launch great applications. This fully illustrated primer teaches important know-how, like how to climb the Linux directory tree, navigate with the File Browser, and much more. Its easy-to-understand tutorials guide readers through the OpenOffice business suite and media applications, letting them enjoy the Web, music, video, and graphics. Later chapters sh

  3. A Significant Step Forward

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Australia officially ratified the Kyoto Protocol on December 3,the first act of its new government under Prime Minister Kevin Rudd.Rudd signed the instrument of ratification the very day he was sworn in by Australia’s Governor General Michael Jeffery. This is a significant step in Australia’s efforts to fight climate change domestically and with the international community,Rudd said in a statement.The Australian Government will do everything in its power to help Australia meet its Kyoto obligations,he added.

  4. Step Motor Control System

    Institute of Scientific and Technical Information of China (English)

    ZhangShuochengt; WangDan; QiaoWeimin; JingLan

    2003-01-01

    All kinds of step motors and servomotors are widely used in CSR control system, such as many vacuum valves control that set on the HIRFL-CSR; all kinds of electric switches and knobs of ECR Ion Source; equipment of CSR Beam Diagnostics and a lot of large equipment like Inside Gun Toroid and Collector Toroid of HIRFL. A typical control system include up to 32 16-I/O Control boards, and each 16-I/O Control board can control 4 motors at the same time (including 8 Limit Switches).

  5. Pressure swing adsorption modeling of acetone and toluene on activated carbon

    Institute of Scientific and Technical Information of China (English)

    唐琳; 李立清; 邢俊东; 刘峥; 姚小龙

    2013-01-01

    A five steps pressure swing adsorption process was designed for acetone and toluene mixtures separation and recovery. Dynamic distributions of gas phase content and temperature were investigated. Based on the theory of Soret and Dufour, a non-isothermal mathematical model was developed to simulate the PSA process. Effects of heat and mass transfer coefficients were studied. The coupled Soret and Dufour effects were also evaluated. It is found that the heat transfer coefficient has little effect on mass transfer in adsorption stage. However, it has some impacts in desorption stage. The maximum value of C/C0 increases by about 25% as heat transfer coefficient decreases. The temperature variation is less than 0.05 K with the change of mass transfer coefficient, so that the effect of mass transfer coefficient on heat transfer can be ignored. It is also concluded that the Soret and Dufour coupled effects are not obvious in pressure swing adsorption compared with fixed-bed adsorption.

  6. Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

    Science.gov (United States)

    Fu, Qingling; Deng, Yali; Li, Huishu; Liu, Jie; Hu, Hongqing; Chen, Shouwen; Sa, Tongmin

    2009-02-01

    The persistence of Bacillus thuringiensis ( Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L -1. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy ( ΔGmθr) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ( ΔHmθr) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  7. Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

    International Nuclear Information System (INIS)

    The persistence of Bacillus thuringiensis (Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L-1. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy (ΔrGmθ) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy (ΔrHmθ) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  8. ADSORPTION CHARACTERIZATION OF CO(II IONS ONTO CHEMICALLY TREATED QUERCUS COCCIFERA SHELL: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDIES

    Directory of Open Access Journals (Sweden)

    M. Hamdi Karaoglu

    2011-04-01

    Full Text Available Quercus coccifera shell (QCS, a relatively abundant and inexpensive material, is currently being investigated as an adsorbent to remove cobalt(II from water. Before the adsorption experiments, QCS was subjected to chemical treatment to provide maximum surface area. Then, the kinetics and adsorption mechanism of Co(II ions on QCS were studied using different parameters such as adsorbent dosage, initial concentration, temperature, contact time, and solution pH. The loaded metals could be desorbed effectively with dilute hydrochloric acid, nitric acid, and 0.1 M EDTA. The Langmuir and Freundlich models were used to describe the uptake of cobalt on QCS. The equilibrium adsorption data were better fitted to Langmuir adsorption isotherm model. The maximum adsorption capacity (qm of QCS for Co(II was 33 mg g-1. Various kinetic models were used to describe the adsorption process. The adsorption followed pseudo second-order kinetic model. The intraparticle diffusion was found to be the rate-limiting step in the adsorption process. The diffusion coefficients were calculated and found to be in the range of 3.11×10−6 to 168.78×10−6 cm2s-1. The negative DH* value indicated exothermic nature of the adsorption.

  9. Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    Fu Qingling; Deng Yali; Li Huishu; Liu Jie [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Hu Hongqing, E-mail: hqhu@mail.hzau.edu.cn [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Chen Shouwen [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Sa Tongmin [Department of Agricultural Chemistry, College of Agriculture, Chungbuk National University, Cheongju, 361-763 (Korea, Republic of)

    2009-02-01

    The persistence of Bacillus thuringiensis (Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L{sup -1}. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy ({Delta}{sub r}G{sub m}{sup {theta}}) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ({Delta}{sub r}H{sub m}{sup {theta}}) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  10. Liquid-liquid extraction and adsorption on solid surfaces applied to used lubricant oils recovery

    Directory of Open Access Journals (Sweden)

    J. L. Assunção Filho

    2010-12-01

    Full Text Available In this work, the recovery of base oils from waste lubricants following the steps of solvent extraction, adsorption on solids and solvent removal by evaporation was evaluated. In the step of solvent extraction, the most efficient was 1-butanol, followed by tert-butanol, 2-propanol and ethanol; for the step of adsorption, activated carbon was the most effective solid for PAH removal, confirming the similarity of these compounds with petroleum aromatic fractions. Thus, the optimum solvent-adsorbent pair for the recovery of used lubricant oils through the proposed methodology was 1-butanol/activated carbon. At the end of the process, it was possible to establish a set of steps that permit the recovery of lubricant base oils with lower content of contaminants.

  11. SPAR-H Step-by-Step Guidance

    Energy Technology Data Exchange (ETDEWEB)

    W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

    2011-05-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  12. Adsorption behavior of bisphenol-A and diethyl phthalate onto bubble surface in nonfoaming adsorptive bubble separation

    OpenAIRE

    Maruyama, Hideo; Seki, Hideshi; Matsukawa, Yasuhiro; Suzuki, Akira; INOUE, Norio

    2008-01-01

    To clarify adsorption equilibrium relationship at liquid-atmosphere interface, adsorption behavior of bisphenol-A (BPA) and diethyl phthalate (DEP) onto bubble surface was studied by using nonfoaming adsorptive bubble separation (NFBS) technique. The adsorption isotherm of BPA and DEP were obtained experimentally. The experimental results showed that adsorption equilibrium of BPA and DEP on bubble surface followed Langmuir's adsorption isotherm. Two adsorption parameters, the adsorption equil...

  13. Heats of adsorption for charcoal nitrogen systems

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, M.; Akkimaradi, B.S.; Rastogi, S.C. [ISRO Satellite Centre, Bangalore (India). Thermal Systems Group; Rao, R.R. [Government College for Boys, Kolar, Karnataka (India); Srinivasan, K. [Indian Institute of Science, Bangalore (India). Dept. of Mechanical Engineering

    1999-07-01

    This paper develops an empirical equation for correlation of the loading dependence of the heat of adsorption for two samples of activated charcoal-nitrogen systems. Details are given of the use of isotherm data, the evaluation of the heat of adsorption using the Clausius-Clapeyron equation, the plotting of primary adsorption data, and the plotting of the heat of adsorption as a function of the loading of the two samples. The need to consider the heat of adsorption property when designing a system in which a gaseous medium is adsorbed by a solid sorbent is discussed. (UK)

  14. Adsorption from solutions of non-electrolytes

    CERN Document Server

    Kipling, J J

    1965-01-01

    Adsorption from Solutions of Non-Electrolytes provides a general discussion of the subject, which has so far been given little or no attention in current textbooks of physical chemistry. A general view of the subject is particularly needed at a time when we wish to see how far it will be possible to use theories of solutions to explain the phenomena of adsorption. The book opens with an introductory chapter on the types of interface, aspects of adsorption from solution, types of adsorption, and classification of systems. This is followed by separate chapters on experimental methods, adsorption

  15. Step & flash imprint lithography

    Directory of Open Access Journals (Sweden)

    Douglas J. Resnick

    2005-02-01

    Full Text Available The escalating cost of next generation lithography (NGL is driven in part by the need for complex sources and optics. The cost for a single NGL tool could soon exceed $50 million, a prohibitive amount for many companies. As a result, several research groups are looking at alternative, low-cost methods for printing sub-100 nm features. Many of these methods are limited in their ability to do precise overlay. In 1999, Willson and Sreenivasan developed step and flash imprint lithography (S-FIL™. The use of a quartz template opens up the potential for optical alignment of the wafer and template. This paper reviews several key aspects of the S-FIL process, including template, tool, ultraviolet (UV-curable monomer, and pattern transfer. Two applications are also presented: contact holes and surface acoustic wave (SAW filters.

  16. Equation of state and adsorption dynamics of soft microgel particles at an air-water interface

    NARCIS (Netherlands)

    Deshmukh, O.S.; Maestro, A.; Duits, M.H.G.; Ende, van den D.T.M.; Cohen Stuart, M.A.; Mugele, F.

    2014-01-01

    Understanding the adsorption dynamics of soft microgel particles is a key step in designing such particles for potential applications as stimuli-responsive Pickering stabilizers for foams or emulsions. In this study we experimentally determine an equation of state (EOS) for poly (N-isopropylacrylami

  17. Adsorption of Phosphate on Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    HUGUO-SONG; ZHUZU-XIANG; 等

    1992-01-01

    The study about the adsorption of phosphate on four variable charge soils and some minerals revealed that two stage adsorption appeared in the adsorption isothems of phosphate on 4 soils and there was a maximum adsorption on Al-oxide-typed surfaces between pH 3.5 to pH 5.5 as suspension pH changed from 2 to 9,but the adsorption amount of phosphate decreased continually as pH rose on Fe-oxide typed surfaces.The adsorption amount of phosphate and the maximum phosphate adsorption pH decreased in the order of yellow-red soil> lateritic red soil> red soil> paddy soil,which was coincided with the content order of amorphous Al oxide.The removement of organic matter and Fe oxide made the maximum phosphate adsorption pH rise from 4.0 to 5.0 and 4.5,respectively.The desorption curves with pH of four soils showed that phosphate desorbed least at pH 5.Generally the desorption was contrary to the adsorption with pH changing.There was a good accordance between adsorption or desorption and the concentration of Al in the suspension.The possible mechanisms of phosphate adsorption are discussed.

  18. Phosphate adsorption on lanthanum loaded biochar.

    Science.gov (United States)

    Wang, Zhanghong; Shen, Dekui; Shen, Fei; Li, Tianyu

    2016-05-01

    To attain a low-cost and high-efficient phosphate adsorbent, lanthanum (La) loaded biochar (La-BC) prepared by a chemical precipitation method was developed. La-BC and its pristine biochar (CK-BC) were comparatively characterized using zeta potential, BET surface area, scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The adsorption ability and the mechanisms during adsorption process for the La-BC samples were also investigated. La loaded on the surface of biochar can be termed as La-composites (such as LaOOH, LaONO3 and La(OH)3), leading to the decrease of negative charge and surface area of biochar. La-BC exhibited the high adsorption capacity to phosphate compared to CK-BC. Adsorption isotherm and adsorption kinetic studies showed that the Langmuir isotherm and second order model could well describe the adsorption process of La-BC, indicating that the adsorption was dominated by a homogeneous and chemical process. The calculated maximum adsorption capacity was as high as 46.37 mg g(-1) (computed in P). Thermodynamic analysis revealed that the adsorption was spontaneous and endothermic. SEM, XRD, XPS and FT-IR analysis suggested that the multi-adsorption mechanisms including precipitation, ligand exchange and complexation interactions can be evidenced during the phosphate adsorption process by La-composites in La-BC. PMID:26871732

  19. Adsorption of amitraz on the clay

    Directory of Open Access Journals (Sweden)

    Jale Gülen

    2013-01-01

    Full Text Available Amitraz (AZ that is used as acaridies was tried to extract with a clay. The experimental data were modelled as using Langmuir and Freundlich isotherms. The adsorption data fit well with Langmuir isotherm that indicated the AZ adsorption is homogeneous and monolayer. The monolayer adsorption capacity was found to be 35.02 mg/g at 20 ºC temperature. Effect of the phases contact time, the initial solution pH and the initial pesticide concentration were investigated from the point of adsorption equilibrium and yield. The adsorption kinetics were investigated by applying pseudo first order, pseudo second order and intra particle diffusion laws. Adsorption of AZ was found to be best fitted by the pseudo second order model. The intra particle diffusion also plays an important role in adsorption phenomenon.

  20. Adsorption modeling for macroscopic contaminant dispersal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Axley, J.W.

    1990-05-01

    Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.

  1. Fibrinogen adsorption on blocked surface of albumin

    DEFF Research Database (Denmark)

    Holmberg, Maria; Hou, Xiaolin

    2011-01-01

    We have investigated the adsorption of albumin and fibrinogen onto PET (polyethylene terephthalate) and glass surfaces and how pre-adsorption of albumin onto these surfaces can affect the adsorption of later added fibrinogen. For materials and devices being exposed to blood, adsorption...... of fibrinogen is often a non-wanted event, since fibrinogen is part of the clotting cascade and unspecific adsorption of fibrinogen can have an influence on the activation of platelets. Albumin is often used as blocking agent for avoiding unspecific protein adsorption onto surfaces in devices designed to handle...... energies, the adsorption of both albumin and fibrinogen has been monitored simultaneously on the same sample. Information about topography and coverage of adsorbed protein layers has been obtained using AFM (Atomic Force Microscopy) analysis in liquid. Our studies show that albumin adsorbs in a multilayer...

  2. Competitive adsorption-desorption reactions of two hazardous heavy metals in contaminated soils.

    Science.gov (United States)

    Davari, Masoud; Rahnemaie, Rasoul; Homaee, Mehdi

    2015-09-01

    Investigating the interactions of heavy metals is imperative for sustaining environment and human health. Among those, Cd is toxic for organisms at any concentration. While Ni acts as a micronutrient at very low concentration but is hazardous toxic above certain threshold value. In this study, the chemical adsorption and desorption reactions of Ni and Cd in contaminated soils were investigated in both single and binary ion systems. Both Ni and Cd experimental data demonstrated Langmuir type adsorption. In the competitive systems, an antagonistic effect was observed, implying that both ions compete for same type of adsorption sites. Adverse effect of Cd on Ni adsorption was slightly stronger than that of opposite system, consistent with adsorption isotherms in single ion systems. Variation in ionic strength indicated that Ca, a much weaker adsorbate, could also compete with Cd and Ni for adsorption on soil particles. Desorption data indicated that Cd and Ni are adsorbed very tightly such that after four successive desorption steps, less than 0.5 % of initially adsorbed ions released into the soil solution. This implies that Ca, at concentration in equilibrium with calcite mineral, cannot adequately compete with and replace adsorbed Ni and Cd ions. This adsorption behavior was led to considerable hysteresis between adsorption and desorption in both single and binary ion systems. In the binary ion systems, desorption of Cd and Ni was increased by increase in both equilibrium concentration of adsorbed ion and concentration of competitor ion. The overall results obtained in this research indicate that Cd and Ni are strongly adsorbed in calcareous soil and Ca, the major dissolved ion, insignificantly influences metal ions adsorption. Consequently, the contaminated soils by Ni and Cd can simultaneously be remediated by environmentally oriented technologies such as phytoremediation. PMID:25921756

  3. Branched pore kinetic model analysis of geosmin adsorption on super-powdered activated carbon.

    Science.gov (United States)

    Matsui, Yoshihiko; Ando, Naoya; Sasaki, Hiroshi; Matsushita, Taku; Ohno, Koichi

    2009-07-01

    Super-powdered activated carbon (S-PAC) is activated carbon of much finer particle size than powdered activated carbon (PAC). Geosmin is a naturally occurring taste and odor compound that impairs aesthetic quality in drinking water. Experiments on geosmin adsorption on S-PAC and PAC were conducted, and the results using adsorption kinetic models were analyzed. PAC pulverization, which produced the S-PAC, did not change geosmin adsorption capacity, and geosmin adsorption capacities did not differ between S-PAC and PAC. Geosmin adsorption kinetics, however, were much higher on S-PAC than on PAC. A solution to the branched pore kinetic model (BPKM) was developed, and experimental adsorption kinetic data were analyzed by BPKM and by a homogeneous surface diffusion model (HSDM). The HSDM describing the adsorption behavior of geosmin required different surface diffusivity values for S-PAC and PAC, which indicated a decrease in surface diffusivity apparently associated with activated carbon particle size. The BPKM, consisting of macropore diffusion followed by mass transfer from macropore to micropore, successfully described the batch adsorption kinetics on S-PAC and PAC with the same set of model parameter values, including surface diffusivity. The BPKM simulation clearly showed geosmin removal was improved as activated carbon particle size decreased. The simulation also implied that the rate-determining step in overall mass transfer shifted from intraparticle radial diffusion in macropores to local mass transfer from macropore to micropore. Sensitivity analysis showed that adsorptive removal of geosmin improved with decrease in activated carbon particle size down to 1microm, but further particle size reduction produced little improvement.

  4. Ethylene dissociation on flat and stepped Ni(111): A combined STM and DFT study

    DEFF Research Database (Denmark)

    Vang, R.T.; Honkala, Johanna Karoliina; Dahl, S.;

    2006-01-01

    The dissociative adsorption of ethylene (C(2)H(4)) on Ni(111) was studied by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The STM studies reveal that ethylene decomposes exclusively at the step edges at room temperature. However, the step edge sites...... are poisoned by the reaction products and thus only a small brim of decomposed ethylene is formed. At 500 K decomposition on the (111) facets leads to a continuous growth of carbidic islands, which nucleate along the step edges. DFT calculations were performed for several intermediate steps...... and DFT results. (c) 2005 Elsevier B.V. All rights reserved....

  5. Direct NO decomposition over stepped transition-metal surfaces

    DEFF Research Database (Denmark)

    Falsig, Hanne; Bligaard, Thomas; Christensen, Claus H.;

    2007-01-01

    We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition-metal surfaces by combining a database of adsorption energies on stepped metal surfaces with known Bronsted-Evans-Polanyi (BEP) relations for the activation barriers of dissociation of...... diatomic molecules over stepped transition- and noble-metal surfaces. The potential energy diagram directly points to why Pd and Pt are the best direct NO decomposition catalysts among the 3d, 4d, and 5d metals. We analyze the NO decomposition reaction in terms of a Sabatier-Gibbs-type analysis, and we...... demonstrate that this type of analysis yields results that to within a surprisingly small margin of error are directly proportional to the measured direct NO decomposition over Ru, Rh, Pt, Pd, Ag, and An. We suggest that Pd, which is a better catalyst than Pt under the employed reaction conditions, is a...

  6. Adsorption and activation of methane and methanol on Pt(100) surface: a density functional study; Adsorption et activation du methane et du methanol sur la surface (100) du platine: une etude par la fonctionnelle de la densite

    Energy Technology Data Exchange (ETDEWEB)

    Moussounda, P.S

    2006-11-15

    The activation of methane (CH{sub 4}) and methanol (CH{sub 3}OH) on Pt(100) surface has been investigated using density functional theory calculations based on plane-wave basis and pseudo-potential. We optimised CH{sub 4}/Pt(100) system. The calculated adsorption energies over the top, bridge and hollow sites are small, weakly dependent on the molecular orientation. The nature of the CH{sub 4}-Pt interaction was examined through the electronic structure changes. The adsorption of methyl (CH{sub 3}) and hydrogen (H) and the co-adsorption of CH{sub 3}+H were also calculated. From these results, we examined the dissociation of CH{sub 4} to CH{sub 3}+H, and the activation energies found are in good agreement with the experimental and theoretical values. The activation of CH{sub 3}OH/Pt(100) has been studied. All the sites have almost the same adsorption energy. The adsorption of oxygen (O) and the co-adsorption of CH{sub 4} and O were also examined. In addition, the formation of CH{sub 3}OH assuming a one-step mechanism step via the co-adsorption of CH{sub 4}+O has been studied and the barrier height was found to be high. (authors)

  7. Inhibition of step movements near equilibrium for sticky steps

    CERN Document Server

    Akutsu, Noriko

    2012-01-01

    Using a Monte Carlo method on a restricted solid-on-solid model with a point-contact type step-step attraction (p-RSOS model), we show that, at low temperature and near equilibrium, there is an inhibition of giant step movements and a self-pinning of steps. The origin of the inhibition of the step movements is the `step faceting', which is caused by a singularity in the anisotropic surface free energy (surface tension). We show that the singularity in the surface free energy results from the sticky steps by using a statistical-mechanical calculation. Further, from the calculation of a surface stiffness tensor, we show that `step droplets', which are locally merged steps and are caused by a singularity in the surface free energy, roughen the vicinal surface. Near equilibrium, however, the step droplets slow down the step velocity due to the diminishment of kinks in the steps. We present an equation for the transport coefficient, which reproduces the Monte Carlo results.

  8. Simulating Succinate-Promoted Dissolution at Calcite {104} Steps

    Science.gov (United States)

    Mkhonto, D.; Sahai, N.

    2008-12-01

    Organic molecules of a wide range of molecular weights from small organic acids, amino-acids, acidic peptides and acidic proteins to humic and fulvic acids play a key role in modulating nucleation, crystal growth and dissolution of calcium carbonate polymorphs. In general, these acidic molecules inhibit calcite growth and, promote dissolution preferentially along specific crystallographic directions, in the process, regulating crystal shape and size, and even whether a metastable polymorph (e.g., vaterite or aragonite) is nucleated first. For example, chiral faces of calcite are selected by chiral amino-acids and the unusual {hk0} faces are expressed in the presence of amino-acids [Orme et al., 2001], and unusual heptagonal dissolution etch-pit are seen in the presence of succinate compared to the normal rhombohedral pits in water alone [Teng et al., 2006]. Thus, the presence of unusual crystal morphologies may indicate organic-mediated growth, thus serving as a biosignature. We have conducted the Molecular Dynamics (MD) simulations using the Consistent Valence Force Field (CVFF) as implemented in the FORCITE© module of the Materials Studio © software package (Accelrys, Inc. TM) to model the adsorption of succinate, a dicarboxylic acid, and charge- balancing Na+ ions on dry and hydrated steps in different directions on the {104} cleavage face of calcite [Mkhonto and Sahai, in prep.]. At the site of succinate adsorption, we find elongation of the interatomic distances (Ca-OCO3,i) between surface Ca2+ cation and the oxygen of the underlying inorganic CO32- anion the first surface layer of calcite, compared to the corresponding distances in the presence of water alone, suggesting greater ease of surface Ca2+ detachment. This result is consistent with the empirically observed increase in overall dissolution rate with succinate [Teng et al., 2006]. Furthermore, succinate adsorption lowers the step energies, which explains the appearance of steps in the unsusual [42

  9. STEPS: JPL's Astrometric Exoplanet Survey

    Science.gov (United States)

    Shaklan, Stuart; Pravdo, Steve

    2008-01-01

    Presentation topics include: STEPS ground-based astrometry at Hale Telescope; the instrument; why astronomy and why M-dwarfs; motion of center of light about center of mass in photocentric orbit; photocentric motion vs. fractional mass; high-resolution imaging of STEPS targets; GU 802 p one possible orbit plotted with data, Keplerian frame; GJ 802 results; STEPS future; and a bibliography of STEPS papers.

  10. SPAR-H Step-by-Step Guidance

    Energy Technology Data Exchange (ETDEWEB)

    April M. Whaley; Dana L. Kelly; Ronald L. Boring; William J. Galyean

    2012-06-01

    Step-by-step guidance was developed recently at Idaho National Laboratory for the US Nuclear Regulatory Commission on the use of the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method for quantifying Human Failure Events (HFEs). This work was done to address SPAR-H user needs, specifically requests for additional guidance on the proper application of various aspects of the methodology. This paper overviews the steps of the SPAR-H analysis process and highlights some of the most important insights gained during the development of the step-by-step directions. This supplemental guidance for analysts is applicable when plant-specific information is available, and goes beyond the general guidance provided in existing SPAR-H documentation. The steps highlighted in this paper are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff.

  11. Adsorption in air treatment; Adsorption en traitement de l'air

    Energy Technology Data Exchange (ETDEWEB)

    Le Cloirec, P. [Ecole des Mines de Nantes, Dept. Systemes Energetiques et Environnement, 44 - Nantes (France)

    2003-01-01

    The aim of this article is to present the concepts and technologies of adsorption in air treatment. The following points are more particularly developed: 1 - approach of mechanisms: gas-solid transfer, equilibrium equations, multi-composed adsorption, adsorption influencing parameters, adsorption-desorption capacities and energies, specific case of hydrogen sulfide, the case of ketones; 2 - adsorbents implemented; 3 - adsorption and dynamical adsorber: flow and pressure drop in a porous medium, breakthrough curves, adsorption capacities, modeling of breakthrough curves; 4 - implementation of adsorber: models, dimensioning and practical operating data, process safety; 5 - regeneration of activated charcoals: reactivation, in-situ thermal regeneration. (J.S.)

  12. Adsorption of Carbon Dioxide on Activated Carbon

    Institute of Scientific and Technical Information of China (English)

    Bo Guo; Liping Chang; Kechang Xie

    2006-01-01

    The adsorption of CO2 on a raw activated carbon A and three modified activated carbon samples B, C, and D at temperatures ranging from 303 to 333 K and the thermodynamics of adsorption have been investigated using a vacuum adsorption apparatus in order to obtain more information about the effect of CO2 on removal of organic sulfur-containing compounds in industrial gases. The active ingredients impregnated in the carbon samples show significant influence on the adsorption for CO2 and its volumes adsorbed on modified carbon samples B, C, and D are all larger than that on the raw carbon sample A. On the other hand, the physical parameters such as surface area, pore volume, and micropore volume of carbon samples show no influence on the adsorbed amount of CO2. The Dubinin-Radushkevich (D-R) equation was the best model for fitting the adsorption data on carbon samples A and B, while the Freundlich equation was the best fit for the adsorption on carbon samples C and D. The isosteric heats of adsorption on carbon samples A, B, C, and D derived from the adsorption isotherms using the Clapeyron equation decreased slightly increasing surface loading. The heat of adsorption lay between 10.5 and 28.4 kJ/mol, with the carbon sample D having the highest value at all surface coverages that were studied. The observed entropy change associated with the adsorption for the carbon samples A, B, and C (above the surface coverage of 7 ml/g) was lower than the theoretical value for mobile adsorption. However, it was higher than the theoretical value for mobile adsorption but lower than the theoretical value for localized adsorption for carbon sample D.

  13. Single PTCDA molecules on planar and stepped KCl and NaCl(100) surfaces

    Science.gov (United States)

    Aldahhak, H.; Schmidt, W. G.; Rauls, E.

    2015-11-01

    First principles calculations have been employed to investigate the adsorption of single PTCDA molecules on KCl(100) and NaCl(100) surfaces. The lateral and rotational diffusion barriers as well as the electronic and the geometric aspects of single PTCDA molecules adsorbed on planar terraces as well as at defective steps have been studied in detail.

  14. BEP-relations for N2 dissociation over stepped transition metal and alloy surfaces

    DEFF Research Database (Denmark)

    Fronczek-Munter, Ture Rønved; Bligaard, Thomas; Christensen, Claus H.;

    2008-01-01

    We present density functional theory (DFT) calculations for N(2) dissociation on stepped face-centred cubic (211) surface slabs. By using the same crystal structure, the same adsorption site for atomic nitrogen, and the same transition-state bond length of N(2) over a range of pure metal surfaces...

  15. Isolation of α-arbutin from Xanthomonas CGMCC 1243 fermentation broth by macroporous resin adsorption chromatography.

    Science.gov (United States)

    Liu, Chunqiao; Zhang, Peng; Liu, Luo; Xu, Tao; Tan, Tianwei; Wang, Fang; Deng, Li

    2013-04-15

    α-Arbutin is a glycosylated hydroquinone which has inhibitory function against tyrosinase. In this work, a one-step isolation of α-arbutin from Xanthomonas CGMCC 1243 fermentation broth by macroporous resin adsorption chromatography was investigated. The research results indicated that S-8 resin offered the best adsorption and desorption capacities for α-arbutin than others and its equilibrium adsorption data were well-fitted to the Freundlich isotherm. In order to optimize the operating parameters for separating α-arbutin, dynamic adsorption and desorption tests on S-8 column chromatography were carried out. Under optimized conditions (adsorption volume of 7 bed volume (BV), mobile phase of 25% (v/v) ethanol solution and elution volume of 3 BV), the purity and recovery of α-arbutin were 97.3% (w/w) and 90.9% (w/w), respectively. The product was identified as α-arbutin by (13)C NMR and (1)H NMR analysis. Moreover, we scaled up S-8 column from laboratory test (10 cm × 2 cm ID) to large scale (500 cm × 100 cm ID) without diminishing α-arbutin yield. In conclusion, the results in this work provide a one-step and cost-effective method for large-scale production of α-arbutin.

  16. Graphene oxide and adsorption of chloroform: A density functional study

    Science.gov (United States)

    Kuisma, Elena; Hansson, C. Fredrik; Lindberg, Th. Benjamin; Gillberg, Christoffer A.; Idh, Sebastian; Schröder, Elsebeth

    2016-05-01

    Chlorinated hydrocarbon compounds are of environmental concerns, since they are toxic to humans and other mammals, and are widespread, and exposure is hard to avoid. Understanding and improving methods to reduce the amount of the substances are important. We present an atomic-scale calculational study of the adsorption of chlorine-based substance chloroform (CHCl3) on graphene oxide, as a step in estimating the capacity of graphene oxide for filtering out such substances, e.g., from drinking water. The calculations are based on density functional theory, and the recently developed consistent-exchange functional for the van der Waals density-functional method is employed. We obtain values of the chloroform adsorption energy varying from roughly 0.2 to 0.4 eV per molecule. This is comparable to previously found results for chloroform adsorbed directly on clean graphene, using similar calculations. In a wet environment, like filters for drinking water, the graphene will not stay clean and will likely oxidize, and thus adsorption onto graphene oxide, rather than clean graphene, is a more relevant process to study.

  17. Step-step interactions on GaAs (110) nanopatterns

    Energy Technology Data Exchange (ETDEWEB)

    Galiana, B.; Benedicto, M.; Tejedor, P. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2013-01-14

    The step-step interactions on vicinal GaAs (110) surface patterns have been extracted from the quantitative analysis of the terrace width distribution (TWD). We have specifically studied the interactions in near-equilibrium faceting and kinetics-driven step bunching and meandering formed by spontaneous self-organization or through the modification of GaAs growth kinetics by atomic hydrogen. We show that the experimental TWDs determined from atomic force microscopy measurements can be accurately described by a weighed sum of a generalized Wigner distribution and several Gaussians. The results of our calculations indicate that straight facets are formed during high temperature homoepitaxy due to attractive interactions between [110] steps. At low temperatures, steady state attractive interactions in [110] step bunches are preceded by a transition regime dominated by entropic and energetic repulsions between meandering [11n]-type steps (n {>=} 2), whose population density exceeds that of the [110] bunched steps. In addition, it has been found that atomic H reduces the attractive interactions between [110] bunched steps and enhances entropic and dipole-induced energetic repulsions between H-terminated [11n] steps through the inhibition of As-As bond formation at step edges. Our analysis has evidenced a correlation between the value of the adjustable parameter that accounts in our model for the specific weight of the secondary peaks in the TWD ({beta}) and the extent of transverse meandering on the vicinal surface.

  18. TREATMENT OF LANDFILL LEACHATE BY COUPLING COAGULATION-FLOCCULATION OR OZONATION TO GRANULAR ACTIVATED CARBON ADSORPTION.

    Science.gov (United States)

    Oloibiri, Violet; Ufomba, Innocent; Chys, Michael; Audenaert, Wim; Demeestere, Kristof; Van Hulle, Stijn W H

    2015-01-01

    A major concern for landfilling facilities is the treatment of their leachate. To optimize organic matter removal from this leachate, the combination of two or more techniques is preferred in order to meet stringent effluent standards. In our study, coagulation-flocculation and ozonation are compared as pre- treatment steps for stabilized landfill leachate prior to granular activated carbon (GAC) adsorption. The efficiency of the pre treatment techniques is evaluated using COD and UVA254 measurements. For coagulation- flocculation, different chemicals are compared and optimal dosages are determined. After this, iron (III) chloride is selected for subsequent adsorption studies due to its high percentage of COD and UVA254 removal and good sludge settle-ability. Our finding show that ozonation as a single treatment is effective in reducing COD in landfill leachate by 66% compared to coagulation flocculation (33%). Meanwhile, coagulation performs better in UVA254 reduction than ozonation. Subsequent GAC adsorption of ozonated effluent, coagulated effluent and untreated leachate resulted in 77%, 53% and 8% total COD removal respectively (after 6 bed volumes). The effect of the pre-treatment techniques on GAC adsorption properties is evaluated experimentally and mathematically using Thomas and Yoon-Nelson models. Mathematical modelling of the experimental GAC adsorption data shows that ozonation increases the adsorption capacity and break through time with a factor of 2.5 compared to coagulation-flocculation.

  19. Treatment of dilute methylene blue-containing wastewater by coupling sawdust adsorption and electrochemical regeneration.

    Science.gov (United States)

    Bouaziz, I; Chiron, C; Abdelhedi, R; Savall, A; Groenen Serrano, K

    2014-01-01

    In the present work, the coupling of adsorption and electrochemical oxidation on a boron-doped diamond (BDD) electrode to treat solutions containing dyes is studied. This coupling may be convenient for the treatment of diluted pollutant that is limited by the low rate of electrooxidation due to mass-transfer limitation. A pre-concentration step by adsorption could minimize the design of the electrochemical reactor. The adsorbent chosen was mixed with softwood sawdust, and methylene blue was chosen as the model dye molecule. Isotherms of adsorption and kinetics were investigated as well as the effects of current density and regeneration time. The BDD electrochemical oxidation of methylene blue adsorbed onto sawdust led simultaneously to its degradation and sawdust regeneration for the next adsorption. It was observed that multiple adsorption and electrochemical regeneration cycles led to an enhancement of adsorption capacity of the sawdust. This study demonstrated that adsorption–electrochemical degradation coupling offers a promising approach for the efficient elimination of organic dyes from wastewater.

  20. Adsorption of indium(III) ions from aqueous solution using chitosan-coated bentonite beads

    Energy Technology Data Exchange (ETDEWEB)

    Calagui, Mary Jane C. [College of Engineering, Cagayan State University, Cagayan Valley 3500 (Philippines); School of Graduate Studies, Mapua Institute of Technology, Manila 1800 (Philippines); Senoro, Delia B. [School of Graduate Studies, Mapua Institute of Technology, Manila 1800 (Philippines); Kan, Chi-Chuan [Institute of Hot Spring Industrial, Chia Nan University of Pharmacy and Science, Tainan 71710, Taiwan (China); Salvacion, Jonathan W.L. [School of Graduate Studies, Mapua Institute of Technology, Manila 1800 (Philippines); Futalan, Cybelle Morales [Operations Department, Frontier Oil Corporation, Makati City 1229 (Philippines); Wan, Meng-Wei, E-mail: peterwan@mail.chna.edu.tw [Department of Environmental Engineering and Science, Chia Nan University of Pharmacy and Science, Tainan 71710, Taiwan (China)

    2014-07-30

    Highlights: • A more acidic pH causes a decrease in adsorption capacity. • The kinetic data follow the pseudo-second order equation. • Equilibrium data correlated well with Langmuir isotherm. • Removal of indium is a spontaneous and endothermic process. - Abstract: Batch adsorption study was utilized in evaluating the potential suitability of chitosan-coated bentonite (CCB) as an adsorbent in the removal of indium ions from aqueous solution. The percentage (%) removal and adsorption capacity of indium(III) were examined as a function of solution pH, initial concentration, adsorbent dosage and temperature. The experimental data were fitted with several isotherm models, where the equilibrium data was best described by Langmuir isotherm. The mean energy (E) value was found in the range of 1–8 kJ/mol, indicating that the governing type of adsorption of indium(III) onto CCB is essentially physical. Thermodynamic parameters, including Gibbs free energy, enthalpy, and entropy indicated that the indium(III) ions adsorption onto CCB was feasible, spontaneous and endothermic in the temperature range of 278–318 K. The kinetics was evaluated utilizing the pseudo-first order and pseudo-second order model. The adsorption kinetics of indium(III) best fits the pseudo-second order (R{sup 2} > 0.99), which implies that chemical sorption as the rate-limiting step.

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

    Science.gov (United States)

    Sarkar, Santanu; Bhattacharjee, Chiranjib; Curcio, Stefano

    2015-11-01

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

  2. Dye Removal From Textile Waste Water Through The Adsorption By Pumice Used In Stone Washing

    Directory of Open Access Journals (Sweden)

    Körlü Aysegül Ekmekçi

    2015-09-01

    Full Text Available Because the waste production is inevitable in almost all industries, the elimination of these wastes is a requirement in terms of environmental regulations and welfare of all the creatures in the future. In this study, the use of the waste pumice stones of a denim washing mill is intended to eliminate the pollutant by a waste material and obtain economic benefits by converting it to the adsorbent. The pollutants in the effluents obtained from three different localisations of waste water treatment system of the same factory were removed through the adsorption. The experimental studies were carried out in three different steps; characterisation of adsorbent before and after adsorption; adsorption isotherm studies and biological oxygen demand (BOD, chemical oxygen demand (COD measurements. Characterisation studies showed that the waste pumice has almost the same structural properties with unused one except the existence of some organic residues coming from washing process. The results of adsorption studies conducted at the adsorbent concentrations changing from 5 to 35 g/l revealed that the decolourisation was initial dye-concentration dependent. According to the BOD and COD measurements, the supernatants obtained at the end of adsorption could be assumed as somewhat polluted and this result indicates that the organic impurities other than indigo were also removed through the adsorption.

  3. Adsorption Behavior of Ferromagnetic Carbon Nanotubes for Methyl Orange from Aqueous Solution.

    Science.gov (United States)

    Wang, Liping; Zhang, Mingyu; Zhao, Chenxi; Yang, Shan

    2016-03-01

    The ferromagnetic carbon nanotubes which can be easily separated from aqueous solution were prepared and characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Batch experiments were carried out to investigate the adsorption behavior of ferromagnetic carbon nanotubes for removing methyl orange (MO). The results showed that these ferromagnetic carbon nanotubes were richer in surface function groups than the carbon nanotubes did, furthermore, both γ-Fe2O3 and Fe with ferromagnetism were found on the surface of carbon nanotubes. The results also demonstrated that ferromagnetic carbon nanotubes possessed stronger adsorption ability for MO than carbon nanotubes did. The adsorption isotherms followed Langmuir isotherm equation and the adsorption kinetics could be well described with the pseudo second-order kinetic model. The adsorption process involved an intraparticle diffusion, while it was not the only rate-controlling step. The values of AG were negative and the value of ΔH is -12.37 kJ/mol, proving that the adsorption of MO onto ferromagnetic carbon nanotubes was a spontaneous and exothermic process. PMID:27455713

  4. Facile synthesis of highly active hydrated yttrium oxide towards arsenate adsorption.

    Science.gov (United States)

    Yu, Yang; Yu, Ling; Sun, Min; Paul Chen, J

    2016-07-15

    A novel hydrated yttrium oxide adsorbent with high capacity towards the arsenate (As(V)) adsorption was fabricated by a one-step hydrothermal process. Structure analysis identified the hydrated yttrium oxide to be Y2O(OH)4·1.5H2O, which displayed as irregular rods in the range of tens to hundreds of nanometers. The adsorbent exhibited favorable As(V) adsorption efficiency in a wide pH range from 4.0 to 7.0, with the maximum adsorption capacity of 480.2mg-As/g obtained at pH 5.0. Both the kinetics and isotherm studies demonstrated that the adsorption of the As(V) was a monolayer chemical adsorption process, in which the ion exchange between the hydroxyl groups on the hydrated yttrium oxide and arsenate anions played a key role in the uptake of the As(V). During the adsorption, the As(V) anions were replaced the hydroxyl groups and bound to the hydrated yttrium oxide via the linkage of AsOY. The presence of fluoride and phosphate greatly hindered the As(V) uptake on the hydrated yttrium oxide, whereas the bicarbonate, sulfate and humic acid showed insignificant impacts on the removal. PMID:27135142

  5. Adsorption and Desorption of Methiopyrsulfuron in Soils

    Institute of Scientific and Technical Information of China (English)

    WU Chun-Xian; WANG Jin-Jun; ZHANG Su-Zhi; ZHANG Zhong-Ming

    2011-01-01

    Methiopyrsulfuron is a new low-rate sulfonylurea herbicide for weed control in wheat; however, there is a lack of published information on its behavior in soils. In this study, methiopyrsulfuron adsorption and desorption were measured in seven soils sampled from Heilongjiang, Shandong, Jiangxi, Sichuan, Anhui, and Chongqing provinces of China using a batch equilibrium method. The Freundlich equation was used to described its adsorption and desorption. Adsorption isotherms were nonlinear with the values of Kf-ads, the Freundlich empirical constant indicative of the adsorption capacity,ranging from 0.75 to 2.46, suggesting that little of this herbicide was adsorbed by any of the seven soils. Soil pH and organic matter content (OM) were the main factors influencing adsorption; adsorption was negatively correlated with pH and positively correlated with OM. Methiopyrsulfuron desorption was hysteretic on the soils with high OM content and low pH.

  6. Gibbs adsorption and the compressibility equation

    International Nuclear Information System (INIS)

    A new approach for deriving the equation of state is developed. It is shown that the integral in the compressibility equation is identical to the isotherm for Gibbs adsorption in radial coordinates. The Henry, Langmuir, and Frumkin adsorption isotherms are converted into equations of state. It is shown that using Henry's law gives an expression for the second virial coefficient that is identical to the result from statistical mechanics. Using the Langmuir isotherm leads to a new analytic expression for the hard-sphere equation of state which can be explicit in either pressure or density. The Frumkin isotherm results in a new equation of state for the square-well potential fluid. Conversely, new adsorption isotherms can be derived from equations of state using the compressibility equation. It is shown that the van der Waals equation gives an adsorption isotherm equation that describes both polymolecular adsorption and the unusual adsorption behavior observed for supercritical fluids. copyright 1995 American Institute of Physics

  7. Effect of piezoelectric material on hydrogen adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuan [Department of Materials Science and Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931 (United States); Civil and Environmental Engineering School, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing, 100083 (China); Hwang, Jiann-Yang; Shi, Shangzhao; Sun, Xiang; Zhang, Zheng [Department of Materials Science and Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931 (United States)

    2010-09-15

    In hydrogen storage applications, the primary issue for physisorption of hydrogen onto solid-state materials is the weak interaction force between hydrogen molecules and the adsorbents. It is found that enhanced adsorption can be obtained under an external electric field, because it appears the electric field increases the hydrogen adsorption energy. Experiments were carried out to determine hydrogen adsorption on activated carbon using the piezoelectric material PMN-PT as the charge supplier under hydrogen pressure. Results indicate that more than 20% hydrogen adsorption enhancement was obtained. Parameters related to hydrogen adsorption enhancement include the amount of the charge and temperature. Higher voltage and lower temperature promote the increase of adsorption capacity but room temperature results are very encouraging. (author)

  8. Adsorption of goethite onto quartz and kaolinite

    Science.gov (United States)

    Goldberg, M.C.; Weiner, Eugene R.; Boymel, P.M.

    1984-01-01

    The adsorption of colloidal goethite onto quartz and kaolinite substrates has been studied as a function of pH and NaCl concentration. Goethite adsorption was measured quantitatively by Fourier-transform infrared spectroscopy. The results indicate that adsorption onto both substrates is due primarily to coulombic forces; however, the pH dependence of adsorption is very different for the two substrates. This is explained by the fact that the surface charge on quartz is entirely pH-dependent, while kaolinite has surface faces which carry a permanent negative charge. Adsorption of goethite on to kaolinite increases markedly with increasing NaCl concentration, while adsorption onto quartz is relatively independent of NaCl concentration. This can be explained by the influence of NaCl concentration upon the development of surface charge on the substrates. A method is described for separating surface-bound goethite from free goethite.

  9. Adsorption of octylamine on titanium dioxide

    International Nuclear Information System (INIS)

    Processes of adsorption and desorption of a model active substance (octylamine) on the surface of unmodified titanium dioxide (E 171) have been performed. The effects of concentration of octylamine and time of the process on the character of adsorption have been studied and the efficiency of the adsorption/desorption has been determined. The samples obtained have been studied by X-ray diffraction. The nitrogen adsorption/desorption isotherms, particle size distribution and absorption capacities of water, dibutyl phthalate and paraffin oil have been determined. The efficiency of octylamine adsorption on the surface of the titanium dioxide has been found positively correlated with the concentration of octylamine in the initial solution. The desorption of octylamine has decreased with increasing concentration of this compound adsorbed. For octylamine in low concentrations the physical adsorption has been found to dominate, which is desirable when using TiO2 in the production of pharmaceuticals.

  10. A theoretical and experimental investigation on the adsorption of pentacene on the Cu(322) surface

    Science.gov (United States)

    Matos, Jeronimo; Sauvage-Simkin, Michele; Coati, Alessandro; Garreau, Yves; Vlad, Alina; Muller, Kathrin; Bendounan, Azzedine; Kara, Abdelkader

    In this study, complementary techniques including density functional theory (DFT), grazing incidence x-ray diffraction (GIXD), and scanning tunneling microscopy (STM) are used to study the surface distortions induced by the adsorption of pentacene on the stepped Cu(322) surface. GIXD measurements are performed for the clean Cu(322) surface and at various coverages of pentacene, up to one monolayer. For the one monolayer case, reciprocal space maps from GIXD measurement suggest the reconstruction of the steps to double the step width and height, with two pentacene molecules present at each terrace. Complementary DFT calculations are carried out, with and without the self-consistent inclusion of vdW interactions, using the optB88-vdW and PBE functionals. Our investigation illustrates a prototype method for conducting future benchmarking studies to assess the accuracy of the current self-consistent vdW functionals when applied to organic molecule adsorption.

  11. Solar heat utilization for adsorption cooling device

    OpenAIRE

    Malcho Milan; Patsch Marek; Pilát Peter

    2012-01-01

    This article deals with possibility of solar system connection with adsorption cooling system. Waste heat from solar collectors in summer is possible to utilize in adsorption cooling systems, which desorption temperatures have to be lower than temperature of heat transport medium operation temperature. For verification of work of this system was constructed on the Department of power engineering on University of Zilina solar adsorption cooling device.

  12. Solar heat utilization for adsorption cooling device

    Directory of Open Access Journals (Sweden)

    Malcho Milan

    2012-04-01

    Full Text Available This article deals with possibility of solar system connection with adsorption cooling system. Waste heat from solar collectors in summer is possible to utilize in adsorption cooling systems, which desorption temperatures have to be lower than temperature of heat transport medium operation temperature. For verification of work of this system was constructed on the Department of power engineering on University of Zilina solar adsorption cooling device.

  13. Bentazone adsorption and desorption on agricultural soils

    OpenAIRE

    Boivin, A.; Cherrier, R.; Schiavon, M

    2005-01-01

    Herbicide fate and transport in soils greatly depend upon adsorption-desorption processes. Batch adsorption and desorption experiments were performed with the herbicide bentazone using 13 contrasted agricultural soil samples. Bentazone was found to be weakly sorbed by the different soils, showing average Freundlich adsorption coefficients (Kf) value of 1.4 ± 2.3 mg1 - nf Lnf kg-1. Soil organic matter content did not have a significant effect on bentazone sorption (r2 = 0.12), whereas natural ...

  14. High Pressure Multicomponent Adsorption in Porous Media

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1999-01-01

    We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent film...... close to a dew point. This equation (asymptotic adsorption equation, AAE) is a first order approximation with regard to the distance from a phase envelope....

  15. Adsorption of L-Phenylalanine on Cu(001)

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; ZHAO Xue-Ying; ZHAO Ru-Guang; yang wei-Sheng

    2001-01-01

    Adsorption of Phenylalanine on a Cu(001) Surface was studied by means of scanning tunnelling microscopy in ultrahihg vacuum and has been found to result in only one superstructure,i.e.,(2×4)Moreover, it induces steps faceting to directions and faceted steps bunching to form{3 1 1 7}facets. In view of the small size of the c(2×4)unit cell,the phenyl ring of the molecule is suggested to be orientated nearly perpendicular rather than parallel to the surface. Amodel has thus been proposed for the c(2×4)superstructure,where the ωstacking interactions between neinhbouring phenyl rngs ,in addition to hydrogen bond formation,are expected to play an important role in the stabilization of the Superstructure

  16. Arsenate adsorption and desorption kinetics on a Fe(III)-modified montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Luengo, Carina; Puccia, Virginia [INQUISUR, Departamento de Quimica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Avena, Marcelo, E-mail: mavena@uns.edu.ar [INQUISUR, Departamento de Quimica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Consejo de Investigaciones Cientificas y Tecnicas de Argentina (CONICET) (Argentina)

    2011-02-28

    Graphical abstract: Arsenate adsorption is much higher in Fe-exchanged montmorillonite (Fe-M) than in Na-exchanged montmorillonite (Na-M). The adsorption takes place in a two-step mechanism. Research highlights: {yields} Adsorption-desorption kinetics of arsenate on a Fe(III)-modified montmorillonite is reported. {yields} Fe(III) species are the responsible for arsenate adsorption. {yields} The adsorption takes place in a two-step mechanism. {yields} Adsorption and desorption studies reflect the presence of externally and internally adsorbed arsenate. {yields} Fe(III) species in Fe-M are more efficient in binding arsenate than in ferrihydrite or goethite. - Abstract: The adsorption-desorption kinetics of arsenate on a Fe(III)-modified montmorillonite (Fe-M) was studied at different arsenate concentrations, pH and stirring rates. The synthesized solid was a porous sample with Fe(III) present as a mix of monomeric and polymeric Fe(III) species in the interlayer and on the external surface. Adsorption took place in a two-step mechanism, with an initial fast binding of arsenate to Fe(III) species at the external surface (half-lives of 1 min or shorter) followed by a slower binding to less accessible Fe(III) species in pores and the interlayer (half-lives of around 1 h). Desorption kinetics also reflected the presence of externally and internally adsorbed arsenate. At pH 6 the maximum adsorbed arsenate was 52 {mu}mol/g, a value that is low as compared to adsorption on ferrihydrite (700 {mu}mol/g) and goethite (192-220 {mu}mol/g). However, since the Fe(III) content of Fe-M is much lower than that of ferrihydrite and goethite, Fe(III) species in Fe-M are more efficient in binding arsenate than in ferrihydrite or goethite (one As atom is attached every 8.95 iron atoms). This high binding efficiency indicates that Fe(III) species are well spread on montmorillonite, forming small oligomeric species or surface clusters containing just a few iron atoms.

  17. Adsorption of radioactive iodide by natural zeolites

    International Nuclear Information System (INIS)

    Two natural zeolites from Iranian deposits (clinoptilolite and natrolite) were characterized and their ability for adsorption of iodide from nuclear wastewaters was evaluated. The adsorption behavior was studied on natural and modified zeolites by γ-spectrometry using 131I as radiotracer. Adsorption isotherms and distribution coefficient (Kd) were measured. The results showed that clinoptilolite is a more promising zeolite for removal of iodide compared to natrolite. Furthermore, the adsorption was higher in silver, lead and thallium forms, whereas the lowest desorption was observed in lead modified zeolite. (author)

  18. Adsorption from Experimental Isotherms of Supercritical Gases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A mathematical method was proposed for the determination of absolute adsorption from experimental isotherms. The method is based on the numerical equality of the absolute and the excess adsorption when either the gas phase density or the amount adsorbed is not quite considerable. The initial part of the experimental isotherms, which represents the absolute adsorption, became linear with some mathematical manipulations. The linear isotherms were reliably formulated. As consequence, either the volume or the density of the supercritical adsorbate could be determined by a non-empirical way. This method was illustrated by the adsorption data of supercritical hydrogen and methane on a superactivated carbon in large ranges of temperature and pressure.

  19. ADSORPTION OF POLYCHLORINATED BIPHENYLS BY SOILS

    Directory of Open Access Journals (Sweden)

    Mihaela Preda

    2010-01-01

    Full Text Available The behavior of polychlorinated biphenyls (PCBs in soil is determined by several factors including adsorption, mobility and degradation. Adsorption, directly or indirectly, influences the other factors. Adsorption process is generally evaluated by using adsorption isotherms representing the relationship between the quantity of substance adsorbed per unit weight and concentration of the substance in solution at equilibrium. They allow determination of the adsorption constant, which is directly proportional to the adsorption of PCBs in soil. PCBs are very insoluble in water, so they tend to accumulate in the lipids. This is the reason why polychlorinated biphenyls are more strongly adsorbed in soils with higher organic matter content. To obtain the adsorption isotherm were used standard solutions of PCB 101with initial concentrations: 0.05, 0.1, 0.5, 1 and 2 g/ml. The adsorption constants were in order: 3072 ml/g for chernozem, 2943 mg/l for chromic luvisol, 998 mg/l for aluviosol and 1443 mg/l for anthrosol. The values of adsorption constants depend on the organic matter and clay content.

  20. Life cycle analysis of solvent reduction in pharmaceutical synthesis using continuous adsorption for palladium removal.

    Science.gov (United States)

    Slater, C Stewart; Savelski, Mariano J; Ruiz-Felix, Marie Nydia

    2013-01-01

    The life cycle emissions associated with the reduction of wastes from an adsorption process to remove palladium complexes in drug manufacture have been evaluated. The study assessed a green improvement to a process step in an active pharmaceutical ingredient synthesis where palladium catalyst is removed from a reaction mixture. The greener process uses a continuous adsorption system, composed of a more efficient adsorbent, consuming less organic solvent and rinse water, which results in less waste disposal. The newer process is also more energy and cost efficient from an operational perspective. There is a 94% reduction in the carbon footprint of the new process when compared to the current operation. PMID:23947697

  1. Adsorption of Polyanion onto Large Alpha Alumina Beads with Variably Charged Surface

    Directory of Open Access Journals (Sweden)

    Tien Duc Pham

    2014-01-01

    Full Text Available Adsorption of strong polyelectrolyte, poly(styrenesulfonate, PSS, of different molecular weights onto large α-Al2O3 beads was systematically investigated as functions of pH and NaCl concentrations. The ultraviolet (UV absorption spectra of PSS at different pH and salt concentrations confirmed that the structure of PSS is independent of pH. With the change of molecular weight from 70 kg/mol (PSS 70 to 1000 kg/mol (PSS 1000, adsorption amount of PSS increases and proton coadsorption on the surface of α-Al2O3 decreases at given pH and salt concentration. It suggests that higher molecular weight of PSS was less flat conformation than lower one. The adsorption density of PSS 70 and PSS 1000 decreases with decreasing salt concentrations, indicating that both electrostatic and nonelectrostatic interactions are involved. Experimental results of both PSS 70 and PSS 1000 adsorption isotherms onto α-Al2O3 at different pH and salt concentrations can be represented well by two-step adsorption model. The effects of molecular weight and salt concentration are explained by structure of adsorbed PSS onto α-Al2O3. The influence of added SDS on the isotherms is evaluated from the sequential adsorption. The SDS uptake onto α-Al2O3 in the presence of hemimicelles can prevent the adsorption of PSS at low concentration so that adsorption of PSS reduces with preadsorbed SDS.

  2. Adsorption analysis equilibria and kinetics

    CERN Document Server

    Do, Duong D

    1998-01-01

    This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such

  3. Annular purpura and step aerobics.

    Science.gov (United States)

    Allan, S J; Humphreys, F; Buxton, P K

    1994-09-01

    Step aerobic classes are at present one of the most popular forms of exercise undertaken by young adults. To date no dermatological abnormalities have been described in people regularly performing step aerobics. We describe a case in which a healthy young woman developed an extensive pigmented purpuric eruption 4 weeks after commencing regular step aerobic classes. The eruption resolved completely 8 weeks after regular exercise was ceased. PMID:7955503

  4. HTSC-Josephson step contacts

    International Nuclear Information System (INIS)

    In this work the properties of josephson step contacts are investigated. After a short introduction into Josephson step contacts the structure, properties and the Josphson contacts of YBa2Cu3O7-x high-Tc superconductors is presented. The fabrication of HTSC step contacts and the microstructure is discussed. The electric properties of these contacts are measured together with the Josephson emission and the magnetic field dependence. The temperature dependence of the stationary transport properties is given. (WL)

  5. Surfactant adsorption to soil components and soils.

    Science.gov (United States)

    Ishiguro, Munehide; Koopal, Luuk K

    2016-05-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on water/air interfaces, the latter gives an impression of surfactant adsorption to a hydrophobic surface and illustrates the importance of the CMC for the adsorption process. Then attention is paid to the most important types of soil particles: humic and fulvic acids, silica, metal oxides and layered aluminosilicates. Information is provided on their structure, surface properties and primary (proton) charge characteristics, which are all important for surfactant binding. Subsequently, the adsorption of different types of surfactants on these individual soil components is discussed in detail, based on mainly experimental results and considering the specific (chemical) and electrostatic interactions, with hydrophobic attraction as an important component of the specific interactions. Adsorption models that can describe the features semi-quantitatively are briefly discussed. In the last part of the paper some trends of surfactant adsorption on soils are briefly discussed together with some complications that may occur and finally the consequences of surfactant adsorption for soil colloidal stability and permeability are considered. When we seek to understand the fate of surfactants in soil and aqueous environments, the hydrophobicity and charge density of the soil or soil particles, must be considered together with the structure, hydrophobicity and charge of the surfactants, because these factors affect the adsorption. The pH and ionic strength are important parameters with respect to the charge density of the particles. As surfactant adsorption influences soil structure and permeability, insight in surfactant adsorption to soil particles is useful for good soil management. PMID

  6. Preface, Soil Science: A step-by-step analysis

    Science.gov (United States)

    This book provides step-by-step procedures for soil professionals, without a lot of background theory. Chapters are targeted toward agricultural and environmental consultants, producers, students, teachers, government, and industry. Applied soil scientists gave input through a survey, which guided t...

  7. HTML5 in easy steps

    CERN Document Server

    McGrath, Mike

    2011-01-01

    Without doubt HTML5 is the future of the web and HTML5 in easy steps demonstrates all you can achieve NOW in the latest browsers - all described in easy to follow steps. HTML5 in easy steps instructs you how to employ the latest development for web page design with HyperText Markup Language (HTML5). Modern web browsers have united to support exciting new features of the HTML5 standard that allows easy creation of stunning web pages and engaging interactive applications. HTML5 in easy steps contains examples and screenshots that illustrate each feature of HTML5, describing how to incorporate me

  8. Simulation studies of the dissociation of H 2 on stepped surfaces

    Science.gov (United States)

    Kaukonen, H.-P.; Nieminen, R. M.

    1991-05-01

    We have simulated the dissociation reaction of H 2 on stepped ideal honeycomb, square and hexagonal surfaces with a simple kinetic model based on the idea proposed by Poelsema and Comsa [Scattering of Thermal Energy Atoms from Disordered Surfaces, Springer Tracts in Modern Physics 115 (Springer, Berlin, 1989)] that dissociation on a stepped Pt(111) surface occurs exclusively on step sites. The observed sticking coefficient sH 2 of H 2 consists of two competing channels: (1) physisorbed molecules incident on terrace sites diffusing to the step, and (2) direct dissociation of molecules incident on or near a step site. The results support this picture qualitatively and indicate that the behaviour of the system can be separated depending on surface temperature into three domains in each of which a different mechanism dominates. (1) T T2: direct adsorption near a step site. Of the three surfaces structures studied the honeycomb structure corresponds most closely to the observed H 2 dissociation.

  9. Investigation on Adsorption State of Surface Adsorbate on Silicon Wafer

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    An adsorption kinetics model for adsorbate on the specularly polished silicon wafer was suggested. The mathematical model of preferential adsorption and the mechanism controlling the adsorption state of adsorbate were discussed.

  10. Adsorption of Nile Blue A from Wastewater Using Magnetic Multi-Walled Carbon Nanotubes: Kinetics and Equilibrium Studies

    Directory of Open Access Journals (Sweden)

    Mehrnaz Ghoochian

    2016-04-01

    Full Text Available Background: Synthetic dyes are serious pollutants and wide ranges of methods have been employed for their removal from aquatic systems. We studied the adsorption of "Nile blue A" (NBA, an anionic dye, from aqueous solution by oxidized multi-walled carbon nanotubes (MWCNTs. Methods: Scanning electron microscope and Fourier transform infrared spectroscopy were used to characterize function groups produced at MWCNTs surface. Kinetics and adsorption isotherms of NBA, the effect of temperature, pH, contact time and initial dosage of nanotubes on the adsorption capacity were also assessed. The experimental data were analyzed by Langmuir and Freundlich models. Results: Most of the dye was removed in the first 5 min and best adsorption percentage was at pH 7.0. The equilibrium reached at 45 min. The experimental data were analyzed by Langmuir and Freundlich models and the results fitted well with the Freundlich model. The adsorption kinetic data were analyzed using first-order and the pseudo-second order model and the adsorption kinetic data of NBA dye onto MWCNTs fitted the pseudo-second order model. The maximum adsorption capacity was obtained as 169.49 mg g-1. Conclusion: Freundlich model suggested that the adsorption process followed heterogeneous distribution onto MWCNTs and pseudo-second model of adsorption implied that chemical processes controlled the rate-controlling step. Oxidized MWCNTs could be used as an effective adsorbent for the removal of "Nile Blue A" dye. Oxidization of MWCNTs by nitric acid, improves the efficiency of NBA removal due to increases in functional groups and total number of adsorption sites.

  11. Adsorption of ferrous ions onto montmorillonites

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Dawei, E-mail: qdw109@163.com [Qilu University of Technology, Jinan, 250353, Shandong (China); Niu, Xia [Qilu University of Technology, Jinan, 250353, Shandong (China); Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao [Shandong SiBang pharmaceutical co., LTD, Jinan, Shandong, 250200 (China)

    2015-04-01

    Highlights: • Adsorption study of ferrous ions on montmorillonites. • Using ascorbic acid as antioxidants in adsorption process. • Fe (II)-MMT had good affinity for phosphate. - Abstract: The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe{sup 2+}/Fe{sub total} ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG{sup 0} and ΔH{sup 0} were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

  12. Adsorption of Chlortetracycline from Water by Rectories

    Institute of Scientific and Technical Information of China (English)

    吕国诚; 吴丽梅; 王晓龙; 廖立兵; 王小雨

    2012-01-01

    The removal of antibiotics from water by clay minerals has become the focus of research due to their strong adsorptive ability. In this study, adsorption of chlortetracycline (CTC) onto rectories was conducted and the effects of time, concentration, temperature and pH were investigated. Experimental results showed that adsorption equilibrium was reached in 8 h. Based on the Langmuir model, the maximum adsorption capacity of CTC on rectories was 177.7 mg·g 1 at room temperature. By the study on adsorption dynamics, it is found that the kinetic date fit the pseudo-second-order model well. The adsorption of CTC by rectories is endothermic and the free energy is in the range of 10 to 30 kJ·mol 1 . The pH value of solution has significant effects on adsorption and the optimal pH is at acidity (pH 2-6). At concentration of 2500 mg·L 1 , the intercalated CTC produces an interlayer space with a height of 1.38 nm, which is 1.12 nm in raw rectories, suggesting that the adsorption occurs between layers of rectories.

  13. Kinetics of polymer adsorption, desorption and exchange.

    NARCIS (Netherlands)

    Dijt, J.C.

    1993-01-01

    The aim of the study in this thesis was to gain more insight in the kinetics of polymer adsorption. To this end some well-characterised polymers have been systematically investigated.In the process of polymer adsorption one may distinguish three kinetic contributions: transport to the surface, attac

  14. Adsorption of arsenic and boron by soil

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, M.

    1986-01-01

    The author reports a study of the soil adsorption of As (trivalent) and B leached from coal ash. It has been found that the amount of adsorption is greatly affected by the pH of the solution. Maximum adsorption of As occurred from solutions with pH of about 8, while pH 8-9 resulted in maximum B adsorption. Furthermore, the As adsorption is related to the quantity of iron oxides and hydrated iron oxides in the soil, while the adsorption of B is related to the quantity of hydrated aluminium oxides and allophanes. Within the range of concentrations studied, the adsorption isotherm for As obeyed the Langmuir equation, and the B isotherm, that of Freundlich. At low concentrations, both elements conform to the Henry adsorption isotherm. The author also reports that the impact on ground water of elements such as As and B leached from coal ash can be conveniently predicted or evaluated by means of a diffusive flow model. 30 references, 14 figures, 3 tables.

  15. Adsorption Kinetic of 8-Hydroxyquinoline on Malachite

    OpenAIRE

    Oprea, Gabriela; Angela MICHNEA; Mihali, Cristina

    2007-01-01

    Influence of temperature and collector concentration on its adsorption rate on mineral surface was studied as regarding to the 8-hydroxyquinoline/malachite system. Theoretical equations as well as experimental data may be useful to estimate the adsorption rate and kinetics connected to the conditioning stage in mineral flotation in order to optimise the selectivity and the recovery of the desired mineral.

  16. Molecular Simulation of Adsorption in Microporous Materials

    OpenAIRE

    Yiannourakou M.; Ungerer P.; Leblanc B.; Rozanska X.; Saxe P.; Vidal-Gilbert S.; Gouth F.; Montel F.

    2013-01-01

    The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications of Monte-Carlo simulation techniques, applied to the adsorption of fluids in microporous solids such as zeolites and model carbons (pores < 2 nm). Adsorption was computed in the Grand Canonical ensemble ...

  17. Study on copper adsorption on olivine

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The copper adsorption on olivine supplied by A/S Olivine production plant at Aheim in western Norway has been studied. The factors which affect the uptake of copper have been evaluated. The results reveal that the equilibrium pH in aqueous solution has the greatest influence on the copper adsorption thanks to the competitive adsorption between proton and copper ions, and the adsorption of copper to olivine increases rapidly with the pH increasing from 4 to 6. The initial copper concentration and olivine dose also possess significant effect on copper adsorption. The adsorption efficieny of copper increases with the increase of olivine dose or the decrease of initial copper concentration at the same pH. The ionic strength effect on the adsorption has also been investigated, but it owns little effect on the adsorption process of copper due to the formation of inner sphere surface complexation of copper on olivine. The experimental data show that olivine has a high acid buffer capacity and is an effective adsorbent for copper.

  18. Adsorption Properties of the Cu(115) Surface

    DEFF Research Database (Denmark)

    Godowski, P. J.; Groso, A.; Hoffmann, S. V.;

    2010-01-01

    in context of substrate geometry and compared with the ones of other copper planes. There are no indications of dissociative adsorption of CO, only residual carbon and oxygen were found after adsorbate desorption around 220 K. CO molecules show a strong tendency to "on top" adsorption in sites far from...

  19. Surfactant adsorption to soil components and soils

    NARCIS (Netherlands)

    Ishiguro, Munehide; Koopal, Luuk K.

    2016-01-01

    Soils are complex and widely varying mixtures of organic matter and inorganic materials; adsorption of surfactants to soils is therefore related to the soil composition. We first discuss the properties of surfactants, including the critical micelle concentration (CMC) and surfactant adsorption on

  20. Development of facile property calculation model for adsorption chillers based on equilibrium adsorption cycle

    Science.gov (United States)

    Yano, Masato; Hirose, Kenji; Yoshikawa, Minoru; Thermal management technology Team

    Facile property calculation model for adsorption chillers was developed based on equilibrium adsorption cycles. Adsorption chillers are one of promising systems that can use heat energy efficiently because adsorption chillers can generate cooling energy using relatively low temperature heat energy. Properties of adsorption chillers are determined by heat source temperatures, adsorption/desorption properties of adsorbent, and kinetics such as heat transfer rate and adsorption/desorption rate etc. In our model, dependence of adsorption chiller properties on heat source temperatures was represented using approximated equilibrium adsorption cycles instead of solving conventional time-dependent differential equations for temperature changes. In addition to equilibrium cycle calculations, we calculated time constants for temperature changes as functions of heat source temperatures, which represent differences between equilibrium cycles and real cycles that stemmed from kinetic adsorption processes. We found that the present approximated equilibrium model could calculate properties of adsorption chillers (driving energies, cooling energies, and COP etc.) under various driving conditions quickly and accurately within average errors of 6% compared to experimental data.

  1. CO2 adsorption on single-walled dahlia-like carbon nanohorns

    Science.gov (United States)

    Bohorquez, Jaime; Krungleviciute, Vaiva; Migone, Aldo; Yudasaka, Masako; Iijima, Sumio

    2010-03-01

    The adsorption of CO2 on spherical aggregates of as-produced (i.e., closed) dahlia-like single-walled carbon nanohorns was investigated. We conducted volumetric adsorption measurements at five temperatures between 147 and 180 K. The shape of the isotherms for CO2 is very different from those measured with neon and CF4. For CO2 there is a single, smeared step in the adsorption data between the lowest coverages and saturation. By contrast, Ne and CF4 show two distinct substeps on the same substrate. The isosteric heat was also obtained and its dependence on coverage also showed an usual behavior: it increased with increasing coverage. The isosteric heat decreases with coverage both for Ne and CF4. The stronger intermolecular interactions present for CO2 probably are responsible for this adsorbate's unusual behavior. Comparisons with the behavior reported in the literature for CO2 on SWNTs, which shows similar unusual characteristics, will also be made.

  2. Adsorption and release of micronutrients by humin extracted from peat samples

    Energy Technology Data Exchange (ETDEWEB)

    Goveia, Danielle; Melo, Camila de A.; Oliveira, Lilian K. de; Rocha, Julio Cesar [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Quimica; Fraceto, Leonardo F.; Rosa, Andre Henrique, E-mail: ahrosa@sorocaba.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil). Departamento de Engenharia Ambiental; Dias Filho, Newton Luiz [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Ilha Solteira, SP (Brazil). Departamento de Fisica e Quimica

    2013-05-15

    The objective of this work was to investigate the adsorption of micronutrients in humin and to verify the ability to release these elements in water. The first step was to determine the adsorption capacity of humin for several essential plant micronutrients and check the kinetic parameters. The order of adsorption was Zn < Ni < Co < Mn < Mo < Cu < Fe, whereas Zn showed maximum values of ca. 2.5 mg g-1 and Fe values of ca. 0.5 mg g-1 for systems containing 1 g of humin. Iron presented higher percentages of release (ca. 100%) and Co the lowest percentages (0.14%). The findings suggested that the use of humin enriched with micronutrients can be a promising alternative for the fertilization of agricultural soils, with the additional benefit of incorporating organic matter present in the form of humic substances into the soil and improving the agricultural productivity. (author)

  3. The Adsorption Properties of Bacillus atrophaeus Spore on Functionalized Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    P. Cortes

    2010-01-01

    Full Text Available An equilibrium study of Bacillus atrophaeus (B.a spores on functionalized Single-Wall Carbon Nanotubes (SWCNTs has been performed in order to characterize the adsorption properties of the spores/nanotubes complex. The carbon nanotubes here investigated were subjected to a two-step purification and functionalization treatment in order to introduce chemical groups on their basal planes. The inclusion of carboxyl functional groups on the nanotubes was corroborated by Raman and infrared spectroscopy. These carboxyl groups appear to enhance the nanotube-B.a. interaction by reacting with the proteinaceous pili appendages present on the spore surface. The adsorption data demonstrate that bacillus spores diffuse faster on functionalized carbon nanotubes than on as-received and purified nanomaterials. Transmission Electron Microscopy also shows that the chemically treated nanotubes resulted in a swollen nano-network which seems to further enhance the bacillus adsorption due to a more extensive spore-nanotube contact area.

  4. Adsorption kinetics of methyl violet onto perlite.

    Science.gov (United States)

    Doğan, Mehmet; Alkan, Mahir

    2003-01-01

    This study examines adsorption kinetics and activation parameters of methyl violet on perlite. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of methyl violet adsorption from solution has been investigated. Results of the kinetic studies show that the adsorption reaction is first order with respect to dye solution concentration with activation energy of 13.2 kJ mol(-1). This low activation energy value indicates that the adsorption reaction is diffusion controlled. The activation parameters using Arrhenius and Eyring equations have been calculated. Adsorption increases with increase of variables such as contact time, initial dye concentration, temperature and pH.

  5. Physical modeling of stepped spillways

    Science.gov (United States)

    Stepped spillways applied to embankment dams are becoming popular for addressing the rehabilitation of aging watershed dams, especially those situated in the urban landscape. Stepped spillways are typically placed over the existing embankment, which provides for minimal disturbance to the original ...

  6. Adsorption and Step Elution of Urokinase Using, Affinity Chromatography -Comparison of Data with Rate Model Simulation

    Institute of Scientific and Technical Information of China (English)

    MohammadRezaAboudzadehRovais; JiawenZhu; BinWu

    2004-01-01

    A non-equilibrium chromatographic rate model was employed to simulate the affinity chromatography of urokinase. The chromatography process was developed to a yield of high purity product of urokinase from crude materials. The affinity gel used in the process was prepared by an epichlorohydrin-activation method using epichlorohydrin activated Sepharose 4B as a matrix and p-aminobenzamidine as a ligand. The chromatographic process were numerically simulated and analyzed with the aid of VERSE-LC computer simulator. Considering the basic principles, rate model with the back mixing in column inlet was utilized in simulating and studying the effect of the column inlet pattern on other parameters. Comparison of the simulation results with the experimental data showed that the rate model can be used to describe the affinity chromatography of urokinase in a fixed bed column with satisfactory accuracy.

  7. A three-step model for protein-gold nanoparticle adsorption

    Science.gov (United States)

    Gold nanoparticles (AuNPs) are an attractive delivery vector in biomedicine because of their low toxicity and unique electronic and chemical properties. AuNP bioconjugates can be used in many applications, including nanomaterials, biosensing, and drug delivery. While the phenomenon of spontaneous pr...

  8. Kinetics of Adsorption of Cationic Surfactants at Silica-Water Interface.

    Science.gov (United States)

    Biswas; Chattoraj

    1998-09-01

    The kinetics of adsorption of cationic surfactants (CTAB, MTAB and DTAB) at silica surface has been studied at various values of bulk surfactant concentration (Ct2), pH, ionic strength, and temperature and in presence of different electrolytes and urea. The adsorption process has been found to follow a two-step first-order kinetic rate equation with two different rate constants k1 and k2. From the variation of k1 and k2 with temperature, values of energies of activation Ea1 and Ea2 for both the kinetic steps have been evaluated. The corresponding values of enthalpies of activation (DeltaH1# and DeltaH2#), entropies of activation (DeltaS1# and DeltaS2#) have been evaluated using Eyring's equation for absolute reaction rate. It has been found that for both the kinetic steps, DeltaH1# 1# and DeltaH2# 2#, which means that activation reaction is largely entropy controlled. Again, for both kinetic steps, DeltaH# varies linearly with TavDeltaS#, and DeltaG1# and DeltaG2# vary between 70 and 88 kJ/mole of surfactant, respectively. Thus there is a entropy-enthalpy compensation effect in the adsorption process. Copyright 1998 Academic Press. PMID:9710495

  9. Separation of toxic rhodamine B from aqueous solution using an efficient low-cost material, Azolla pinnata, by adsorption method.

    Science.gov (United States)

    Kooh, Muhammad Raziq Rahimi; Lim, Linda B L; Lim, Lee Hoon; Dahri, Muhammad Khairud

    2016-02-01

    This study investigated the potential of untreated Azolla pinnata (AP) to remove toxic rhodamine B (RB) dye. The effects of adsorbent dosage, pH, ionic strength, contact time, and concentration were studied. Experiments involving the effects of pH and ionic strength indicated that hydrophobic-hydrophobic interactions might be the dominant force of attraction for the RB-AP adsorption system. The kinetics modelling of the kinetics experiment showed that pseudo-second-order best represented the adsorption process. The Weber-Morris intraparticle diffusion model showed that intraparticle diffusion is not the rate-limiting step, while the Boyd model suggested that film diffusion might be rate-limiting. The adsorption isotherm model, Langmuir, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 72.2 and 199.7 mg g(-1) at 25 and 65 °C, respectively. Thermodynamics study indicates spontaneity, endothermic and physisorption-dominant adsorption process. The adsorbents were regenerated to satisfactory level with distilled water, HNO3 and NaOH. Pre-treatment of adsorbent with oxalic acid, citric acid, NaOH, HCl and phosphoric acid was investigated but the adsorption capacity was less than the untreated AP. PMID:26797814

  10. Separation of toxic rhodamine B from aqueous solution using an efficient low-cost material, Azolla pinnata, by adsorption method.

    Science.gov (United States)

    Kooh, Muhammad Raziq Rahimi; Lim, Linda B L; Lim, Lee Hoon; Dahri, Muhammad Khairud

    2016-02-01

    This study investigated the potential of untreated Azolla pinnata (AP) to remove toxic rhodamine B (RB) dye. The effects of adsorbent dosage, pH, ionic strength, contact time, and concentration were studied. Experiments involving the effects of pH and ionic strength indicated that hydrophobic-hydrophobic interactions might be the dominant force of attraction for the RB-AP adsorption system. The kinetics modelling of the kinetics experiment showed that pseudo-second-order best represented the adsorption process. The Weber-Morris intraparticle diffusion model showed that intraparticle diffusion is not the rate-limiting step, while the Boyd model suggested that film diffusion might be rate-limiting. The adsorption isotherm model, Langmuir, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 72.2 and 199.7 mg g(-1) at 25 and 65 °C, respectively. Thermodynamics study indicates spontaneity, endothermic and physisorption-dominant adsorption process. The adsorbents were regenerated to satisfactory level with distilled water, HNO3 and NaOH. Pre-treatment of adsorbent with oxalic acid, citric acid, NaOH, HCl and phosphoric acid was investigated but the adsorption capacity was less than the untreated AP.

  11. A new porous magnetic chitosan modified by melamine for fast and efficient adsorption of Cu(II) ions.

    Science.gov (United States)

    Wu, Zhan-Chao; Wang, Zhao-Zhan; Liu, Jie; Yin, Jin-Hua; Kuang, Shao-Ping

    2015-11-01

    A new porous magnetic chitosan modified by melamine (MA-CS/Fe3O4) was synthesized. The compositions and surface topographies were characterized by infrared (IR) spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric (TG) analysis and scanning electron microscope (SEM), respectively. The results of adsorption kinetics showed the adsorption behavior could be better described by the pseudo-second-order equation (R>0.999). The adsorption isotherm was well fitted by the Langmuir equation (R>0.999), and the values of separation factors were in the range of 0-1.0. The maximum adsorption capacity for Cu(II) was 2.58mmolg(-1) at the optimal experimental conditions, which were pH=5.5, t=25min, C0=5.0mmolL(-1). The rate-controlling step was supposed to be chemical adsorption rather than mass transport. The adsorbent still exhibited high adsorption capacity after five regeneration cycles. The adsorption mechanism was due to coordination between Cu(II) and N atoms.

  12. Adsorption of Cu(II), Co(II), and Ni(II) ions by modified magnetic chitosan chelating resin

    International Nuclear Information System (INIS)

    Cross-linked magnetic chitosan-isatin Schiff's base resin (CSIS) was prepared for adsorption of metal ions. CSIS obtained was investigated by means of FTIR, 1H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSIS resin toward Cu2+, Co2+ and Ni2+ ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 103.16, 53.51, and 40.15 mg/g for Cu2+, Co2+ and Ni2+ ions, respectively. Cross-linked magnetic CSIS displayed higher adsorption capacity for Cu2+ in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSIS were regenerated with an efficiency of greater than 88% using 0.01-0.1 M ethylendiamine tetraacetic acid (EDTA).

  13. Adsorption of Cu(II), Co(II), and Ni(II) ions by modified magnetic chitosan chelating resin.

    Science.gov (United States)

    Monier, M; Ayad, D M; Wei, Y; Sarhan, A A

    2010-05-15

    Cross-linked magnetic chitosan-isatin Schiff's base resin (CSIS) was prepared for adsorption of metal ions. CSIS obtained was investigated by means of FTIR, (1)H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSIS resin toward Cu(2+), Co(2+) and Ni(2+) ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 103.16, 53.51, and 40.15mg/g for Cu(2+), Co(2+) and Ni(2+) ions, respectively. Cross-linked magnetic CSIS displayed higher adsorption capacity for Cu(2+) in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSIS were regenerated with an efficiency of greater than 88% using 0.01-0.1M ethylendiamine tetraacetic acid (EDTA). PMID:20122793

  14. ADSORPTION OF PROTEIN ON NANOPARTICLES

    Institute of Scientific and Technical Information of China (English)

    WU Qi

    1994-01-01

    The adsorption of protein on nanoparticles was studied by using dynamic light scattering to measure the hydrodynamic size of both pure protein and nanoparticles adsorbed with different amounts of protein. The thickness of the adsorbed protein layer increases as protein concentration, but decreases as the initial size of nanoparticles. After properly scaling the thickness with the initial diameter, we are able to fit all experimental data with a single master curve. Our experimental results suggest that the adsorbed proteins form a monolayeron the nanoparticle surface and the adsorbed protein molecules are attached to the particle surface at many points through a possible hydrogen-bonding. Our results also indicate that as protein concentration increases, the overall shape of the adsorbed protein molecule continuously changes from a flat layer on the particle surface to a stretched coil extended into water. During the change, the hydrodynamic volume of the adsorbed protein increases linearly with protein concentration.

  15. Adsorption on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    DING Yi; YANG Xiao-bao; NI Jun

    2006-01-01

    Adsorption on single walled carbon nanotubes (SWCNTs) is a subject of growing experimental and theoretical interest.The possible adsorbed patterns of atoms and molecules on the single-walled carbon nanotubes vary with the diameters and chirality of the tubes due to the confinement.The curvature of the carbon nanotube surface enlarges the distance of the adsorbate atoms and thus enhances the stability of high coverage structures of adsorbate.There exist two novel high-coverage stable structures of potassium adsorbed on SWCNTs,which are not stable on graphite.The electronic properties of SWCNTs can be modified by adsorbate atoms and metal-semiconductor and semiconductor-semi-conductor transitions can be achieved by the doping of alkali atoms.

  16. Adsorption of organic matter contained in industrial phosphoric acid onto bentonite: Batch contact time and kinetic study

    International Nuclear Information System (INIS)

    The soluble organic matter present in industrial phosphoric acid can strongly affect the uranium recovery during its solvent extraction by forming stable foams and emulsions. The removal of these organics is an important step both for the production of decontaminated fertilizers and the successful recovery of uranium. The equilibrium isotherms of organic matter adsorption onto bentonite show that the data correlated well with freundlich's model and that the adsorption is physical in nature. the maximum monomolecular capacity (Qo) according to the Langmuir model is 153 mg/g for an initial organic matter concentration of 251.5 mg/1, at 30 oC. The operating parameters (agitation speed, solid/liquid ratio, temperature, particle size and initial organic matter concentration) influenced the rate of adsorption. The adsorption isotherm of uranium onto bentonite exhibits and anomalous shape similar to the Z-type isotherm reported by Giles et al

  17. Peat and coconut fiber as biofilters for chromium adsorption from contaminated wastewaters.

    Science.gov (United States)

    Henryk, Kołoczek; Jarosław, Chwastowski; Witold, Żukowski

    2016-01-01

    Batch adsorption experiments were performed for the removal of chromium (III) and chromium (VI) ions from aqueous solutions using Canadian peat and coconut fiber. The Langmuir model was used to describe the adsorption isotherm. The maximum adsorption for peat reached 18.75 mg/g for Cr(III) and 8.02 mg/g for Cr(VI), whereas the value for fiber was slightly higher and reached 19.21 mg/g for Cr(III) and 9.54 mg/g for Cr(VI). Both chromium forms could be easily eluted from the materials. The adsorption of chromium forms to organic matter could be explained in terms of formation of donor-acceptor chemical covalent bound with hydroxyl groups as ligands and chromium as the central atom in the formed complex. The chromate-reducing activities were monitored with the use of electron paramagnetic resonance spectroscopy. The results showed that both adsorption and reduction occurred simultaneously and the maximum adsorption capacity of hexavalent chromium being equal to 95% for fiber and 92% for peat was obtained at pH 1.5. The reduction of Cr(VI) in wastewaters began immediately and disappeared after 20 h. Both materials contained yeast and fungi species which can be responsible for reduction of chromium compounds, due to their enzymatic activity (Chwastowski and Koloczek (Acta Biochim Pol 60: 829-834, 2013)). The reduction of Cr(VI) is a two-phase process, the first phase being rapid and based on chemical reaction and the second phase having biological features. After the recovery step, both types of organic materials can be used again for chromium adsorption without any loss in the metal uptake. Both of the materials could be used as biofilters in the wastewater treatment plants.

  18. Two-step electroweak baryogenesis

    Science.gov (United States)

    Inoue, Satoru; Ovanesyan, Grigory; Ramsey-Musolf, Michael J.

    2016-01-01

    We analyze electroweak baryogenesis during a two-step electroweak symmetry-breaking transition, wherein the baryon asymmetry is generated during the first step and preserved during the second. Focusing on the dynamics of C P violation required for asymmetry generation, we discuss general considerations for successful two-step baryogenesis. Using a concrete model realization, we illustrate in detail the viability of this scenario and the implications for present and future electric dipole moment (EDM) searches. We find that C P violation associated with a partially excluded sector may yield the observed baryon asymmetry while evading present and future EDM constraints.

  19. Two-Step Electroweak Baryogenesis

    CERN Document Server

    Inoue, Satoru; Ramsey-Musolf, Michael J

    2016-01-01

    We analyze electroweak baryogenesis during a two-step electroweak symmetry breaking transition, wherein the baryon asymmetry is generated during the first step and preserved during the second. Focusing on the dynamics of CP-violation required for asymmetry generation, we discuss general considerations for successful two-step baryogenesis. Using a concrete model realization, we illustrate in detail the viability of this scenario and the implications for present and future electric dipole moment (EDM) searches. We find that CP-violation associated with a partially excluded sector may yield the observed baryon asymmetry while evading present and future EDM constraints.

  20. Modeling the adsorption of mixed gases based on pure gas adsorption properties

    Science.gov (United States)

    Tzabar, N.; Holland, H. J.; Vermeer, C. H.; ter Brake, H. J. M.

    2015-12-01

    Sorption-based Joule-Thomson (JT) cryocoolers usually operate with pure gases. A sorption-based compressor has many benefits; however, it is limited by the pressure ratios it can provide. Using a mixed-refrigerant (MR) instead of a pure refrigerant in JT cryocoolers allows working at much lower pressure ratios. Therefore, it is attractive using MRs in sorption- based cryocoolers in order to reduce one of its main limitations. The adsorption of mixed gases is usually investigated under steady-state conditions, mainly for storage and separation processes. However, the process in a sorption compressor goes through various temperatures, pressures and adsorption concentrations; therefore, it differs from the common mixed gases adsorption applications. In order to simulate the sorption process in a compressor a numerical analysis for mixed gases is developed, based on pure gas adsorption characteristics. The pure gas adsorption properties have been measured for four gases (nitrogen, methane, ethane, and propane) with Norit-RB2 activated carbon. A single adsorption model is desired to describe the adsorption of all four gases. This model is further developed to a mixed-gas adsorption model. In future work more adsorbents will be tested using these four gases and the adsorption model will be verified against experimental results of mixed-gas adsorption measurements.

  1. Removal and recovery of hazardous triphenylmethane dye, Methyl Violet through adsorption over granulated waste materials

    International Nuclear Information System (INIS)

    Bottom Ash a power plant waste material and De-Oiled Soya, an agricultural waste product have been successfully used for the removal and recovery of a hazardous triphenylmethane dye-Methyl Violet, from wastewaters. The characterization of each adsorbent has been carried out by I.R. and D.T.A. curves. Batch adsorption studies have been made by measuring effects of pH, sieve size, amount of adsorbent, contact time, temperature, concentration of the adsorbate solution, etc. Kinetic studies have been used to determine the nature of rate controlling step of the processes and confirm the applicability of the first order rate expression in the ongoing adsorption process. Various thermodynamic parameters have also been calculated by applying the linear forms of Langmuir and Freundlich adsorption isotherms. The linear nature of adsorption isotherms obtained shows the dependence of the processes on the Freundlich and Langmuir isotherm models. Furthermore, to ascertain the adsorption processes to be particle diffusion or film diffusion mechanism, Boyd and Reichenberg's expressions have been applied. For both the adsorbents, column operations have been carried out for the bulk removal of the dye. The adsorbed dye has been recovered by eluting hydrochloric acid of pH 3 through exhausted columns

  2. The surface modification of stainless steel and the correlation between the surface properties and protein adsorption.

    Science.gov (United States)

    Kang, Chan-Koo; Lee, Yoon-Sik

    2007-07-01

    Protein adsorption on a biomaterial surface is of great importance as it usually induces unfavorable biological cascades, with the result that much surface modification research has had to be performed in an effort to prevent this. In this study, we developed surface modification methods for stainless steel, which is a representative metal for biomedical device. The stainless steels were first smoothened to different extents by electropolishing, in order to obtain a rough or smooth surface. On these two kinds of substrates, we introduced epoxide groups to the metal surface by silanization with 3-glycidoxypropyltrimethoxysilane (GPTS). Then, various polymers such as poly(ethylene glycol) (PEG), poly(tetrahydrofuran glycol) (PTG), poly(propylene glycol) (PPG) and poly(dimethylsiloxane) (PDMS) were grafted on the silanized stainless steels. Each surface modification step was confirmed by various analytical methods. Contact angle measurement revealed that the surface hydrophilicity was controllable by polymer grafting. Root-mean-square (RMS) data of atomic force microscopy showed that surface roughness was dramatically changed by electropolishing. Based on these results, the correlation between surface properties and protein adsorption was investigated. In the protein adsorption study, we observed that all of the polymer-grafted stainless steels exhibited lower protein adsorption, when compared with bare stainless steel. Moreover, a hydrophilic and smooth surface was found to be the best of choice for decreasing the protein adsorption. PMID:17277988

  3. Effect of temperature and kinetic modelling of lignosulfonate adsorption onto powdered eggshell in batch systems

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Zulfikar

    2013-06-01

    Full Text Available The sorption of lignosulfonate onto powdered eggshell under the influence of temperature has been studied. The rate of adsorption onto eggshell was investigated under a variety of adsorbent dosages. The kinetic data from these investigations were correlated to a number of adsorption models in an attempt to elucidate the mechanism of the adsorption processes. Thermodynamic parameter data indicated that the lignosulfonate sorption process was non-spontaneous and endothermic under the experimental conditions, with the Gibbs free energy (Go in the range of 1.83-1.07 kJ mol-1, enthalpy (Ho andentropy (So of 5.66 kJ mol-1 and 12.82 J mol-1, respectively and the activation energy of 18.17 kJ mol-1. The adsorption mechanism was found to follow a pseudo-second-order model, with the kinetic constants in the range of 0.689–1.430 g mg-1 min-1. Both the intra-particle diffusion and Boyd kinetic models indicated that boundary layer/film diffusion was the main rate determining step in lignosulfonate adsorption process.

  4. Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

    Science.gov (United States)

    Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

    2015-12-01

    In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

  5. Adsorption of Iminodiacetic Acid Resin for Lutetium

    Institute of Scientific and Technical Information of China (English)

    熊春华; 姚彩萍; 王惠君

    2004-01-01

    The adsorption behavior and mechanism of a novel chelate resin,iminodiacetic acid resin(IDAAR) for Lu(Ⅲ) were investigated.The statically saturated adsorption capacity is 210.8 mg·g-1 at 298 K in HAc-NaAc medium.The Lu(Ⅲ) adsorbed on IDAAR can be eluted by 0.5 mol·L-1 HCl and the elution percentage reaches 96.5%.The resin can be regenerated and reused without obvious decrease in adsorption capacity.The apparent adsorption rate constant is k298=2.0×10-5 s-1.The adsorption behavior of IDAAR for Lu(Ⅲ) obeys the Freundlich isotherm.The thermodynamic adsorption parameters,enthalpy change ΔH,free energy change ΔG and entropy change ΔS of IDAAR for Lu(Ⅲ) are 13.1 kJ·mol-1,-1.37 kJ·mol-1 and 48.4 J·mol-1·K-1,respectively.The apparent activation energy is Ea=31.3 kJ·mol-1.The molar coordination ratio of the functional group of IDAAR to Lu(Ⅲ) is about 3∶1.The adsorption mechanism of IDAAR for Lu(Ⅲ) was examined by chemical method and IR spectrometry.

  6. Adsorption of gases on heterogeneous surfaces

    CERN Document Server

    Rudzinski, W

    1991-01-01

    All real solid surfaces are heterogeneous to a greater or lesser extent and this book provides a broad yet detailed survey of the present state of gas adsorption. Coverage is comprehensive and extends from basic principles to computer simulation of adsorption. Underlying concepts are clarified and the strengths and weaknesses of the various methods described are discussed.Key Features* Adsorption isotherm equations for various types of heterogeneous solid surfaces* Methods of determining the nature of surface heterogeneity and porosity from experimental data* Studies of pha

  7. Adsorption of lead over graphite oxide.

    Science.gov (United States)

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

    2014-01-24

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb(2+) was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water.

  8. Adsorption of Cadmium By Silica Chitosan

    OpenAIRE

    Moftah Ali; Ani Mulyasuryani; Akhmad Sabarudin

    2013-01-01

    The adsorption process depends on initial concentration of Cd2+ and ratio of  chitosan in adsorbent. The present study deals with the competitive adsorption of Cd2+ ion onto silica graft with chitosan. Batch adsorption experiments were performed at five different initial Cd2+ concentrations (5, 10, 15, 20 and 25 ppm), on five different proportion from silica to chitosan (100%, 95%, 85%, 75% and 65%) as adsorbent at pH 5. In the recovery process, the high recovery at 0.5 mg and observed the re...

  9. Adsorption affinity of anions on metal oxyhydroxides

    Science.gov (United States)

    Pechenyuk, S. I.; Semushina, Yu. P.; Kuz'mich, L. F.

    2013-03-01

    The dependences of anion (phosphate, carbonate, sulfate, chromate, oxalate, tartrate, and citrate) adsorption affinity anions from geometric characteristics, acid-base properties, and complex forming ability are generalized. It is shown that adsorption depends on the nature of both the anions and the ionic medium and adsorbent. It is established that anions are generally grouped into the following series of adsorption affinity reduction: PO{4/3-}, CO{3/2-} > C2O{4/2-}, C(OH)(CH2)2(COO){3/3-}, (CHOH)2(COO){2/2-} > CrO{4/2-} ≫ SO{4/2-}.

  10. Adsorption-Induced Deformation of Mesoporous Solids

    CERN Document Server

    Gor, Gennady Yu

    2010-01-01

    The Derjaguin - Broekhoff - de Boer theory of capillary condensation is employed to describe deformation of mesoporous solids in the course of adsorption-desorption hysteretic cycles. We suggest a thermodynamic model, which relates the mechanical stress induced by adsorbed phase with the adsorption isotherm. Analytical expressions are derived for the dependence of the solvation pressure on the vapor pressure. The proposed method provides a semi-quantitative description of non-monotonic hysteretic deformation during capillary condensation without invoking any adjustable parameters. The method is showcased drawing on the examples of literature experimental data on adsorption deformation of porous glass and SBA-15 silica.

  11. Oxidized dahlia-like carbon nanohorns: adsorption of argon, methane and nitrogen

    Science.gov (United States)

    Krungleviciute, Vaiva; Migone, Aldo; Yudasaka, Masako; Iijima, Sumio

    2010-03-01

    Different types of nanohorns, and nanohorn aggregates, can be produced depending on the parameters used during their production. We used a sample consisting mainly of dahlia-like nanohorn aggregates. In the dahlia-like aggregates the individual nanohorns are aligned radially, forming a sphere, with their individual ends protruding from the outer surface of the spherule. Our sample was oxidized by flowing pure oxygen. This treatment opened entry ports into the spaces at the interior of the individual nanohorns. We measured volumetric adsorption isotherms at 77.3 K with argon, methane, and nitrogen. For argon and methane two distinct substeps are present in the adsorption data; the steps for each of these two gases are comparable in size. For nitrogen there is a clear step present at lower adsorbent loadings, and a more gradual growth in the amount adsorbed as saturation is approached.

  12. Application of ultrasonic backscattering for level measurement and process monitoring of expanded-bed adsorption columns.

    Science.gov (United States)

    Thelen, T V; Mairal, A P; Thorsen, C S; Ramirez, W F

    1997-01-01

    Expanded-bed adsorption is a newly commercialized technique for the purification of proteins from cellular debris in downstream processing. An expanded bed presents the possibility of protein recovery in a single step, eliminating the often costly clarification processing steps such as ultrafiltration, centrifugation, and precipitation. A major obstacle to the successful commercialization of this technology is the inability to accurately monitor and control the bed height in these systems. Fluctuations in the feedstock viscosity are common during normal operation and tend to make the operation and control of expanded beds for biological applications complex and difficult. We develop a level measurement technique based upon ultrasonics. It is shown that this technique has great promise for bed-height measurement in expanded-bed adsorption systems. Furthermore, the bed-height measurement can be used in feedback control strategies for bed-height regulation. The proposed ultrasonic sensor is also capable of monitoring for plugging and bubbling in the column. PMID:9336988

  13. Albumin (BSA) Adsorption over Graphene in Aqueous Environment: Influence of Orientation, Adsorption Protocol, and Solvent Treatment.

    Science.gov (United States)

    Vilhena, J G; Rubio-Pereda, Pamela; Vellosillo, Perceval; Serena, P A; Pérez, Rubén

    2016-02-23

    We report 150 ns explicit solvent MD simulations of the adsorption on graphene of albumin (BSA) in two orientations and using two different adsorption protocols, i.e., free and forced adsorption. Our results show that free adsorption occurs with little structural rearrangements. Even taking adsorption to an extreme, by forcing it with a 5 nN downward force applied during the initial 20 ns, we show that along a particular orientation BSA is able to preserve the structural properties of the majority of its binding sites. Furthermore, in all the cases considered in this work, the ibuprofen binding site has shown a strong resilience to structural changes. Finally, we compare these results with implicit solvent simulations and find that the latter predicts an extreme protein unfolding upon adsorption. The origin of this discrepancy is attributed to a poor description of the water entropic forces at interfaces in the implicit solvent methods.

  14. Creating single-atom Pt-ceria catalysts by surface step decoration

    Science.gov (United States)

    Dvořák, Filip; Farnesi Camellone, Matteo; Tovt, Andrii; Tran, Nguyen-Dung; Negreiros, Fabio R.; Vorokhta, Mykhailo; Skála, Tomáš; Matolínová, Iva; Mysliveček, Josef; Matolín, Vladimír; Fabris, Stefano

    2016-02-01

    Single-atom catalysts maximize the utilization of supported precious metals by exposing every single metal atom to reactants. To avoid sintering and deactivation at realistic reaction conditions, single metal atoms are stabilized by specific adsorption sites on catalyst substrates. Here we show by combining photoelectron spectroscopy, scanning tunnelling microscopy and density functional theory calculations that Pt single atoms on ceria are stabilized by the most ubiquitous defects on solid surfaces--monoatomic step edges. Pt segregation at steps leads to stable dispersions of single Pt2+ ions in planar PtO4 moieties incorporating excess O atoms and contributing to oxygen storage capacity of ceria. We experimentally control the step density on our samples, to maximize the coverage of monodispersed Pt2+ and demonstrate that step engineering and step decoration represent effective strategies for understanding and design of new single-atom catalysts.

  15. Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.

    Science.gov (United States)

    Altmann, Johannes; Zietzschmann, Frederik; Geiling, Eva-Linde; Ruhl, Aki Sebastian; Sperlich, Alexander; Jekel, Martin

    2015-04-01

    The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing. PMID:25582393

  16. Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.

    Science.gov (United States)

    Altmann, Johannes; Zietzschmann, Frederik; Geiling, Eva-Linde; Ruhl, Aki Sebastian; Sperlich, Alexander; Jekel, Martin

    2015-04-01

    The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing.

  17. Understanding the Optimal Adsorption Energies for Catalyst Screening in Heterogeneous Catalysis

    OpenAIRE

    Yang, Bo; Burch, Robbie; Hardacre, Christopher; Headdock, Gareth; Hu, P

    2014-01-01

    The fundamental understanding of the activity in heterogeneous catalysis has long been the major subject in chemistry. This paper shows the development of a two-step model to understand this activity. Using the theory of chemical potential kinetics with Bronsted-Evans-Polanyi relations, the general adsorption energy window is determined from volcano curves, using which the best catalysts can be searched. Significant insights into the reasons for catalytic activity are obtained.

  18. Kinetic studies of zinc ions removal from aqueous solution by adsorption on natural zeolite

    OpenAIRE

    Zendelska, Afrodita; Golomeova, Mirjana; Blažev, Krsto; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar

    2014-01-01

    The kinetics of zinc adsorption onto natural zeolite (clinoptilolite) were studied with respect to initial metal ion concentration, adsorbent mass and initial pH value. In order to select the main rate-determining step in the overall uptake mechanism, a series of experiments were performed under batch conditions from single ion solutions. Data obtained from the kinetic experiments are interpreted in terms of Pseudo-second order kinetic model, Weber and Morris model and mod...

  19. Adsorption of fucoidan and chitosan sulfate on chitosan modified PET films monitored by QCM-D

    OpenAIRE

    Indest, Tea; Laine, Janne; Johansson, Leena Sisko; Stana-Kleinschek, Karin; Strnad, Simona; Dworczak, Renate; Ribitsch, Volker

    2012-01-01

    The adsorption behavior of fucoidan as well as chitosan derivatives (chitosan sulfate) on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance technique. These systems were chosen for this study due to their promising biocompatible properties. Moreover, fucoidan and chitosan sulfate have promising anticoagulant properties and represent an alternative to heparin treatment of vascular grafts. As a first step, PET foils were activated by alkalin...

  20. Preimages for Step-Reduced SHA-2

    DEFF Research Database (Denmark)

    Aoki, Kazumaro; Guo, Jian; Matusiewicz, Krystian;

    2009-01-01

    In this paper, we present preimage attacks on up to 43-step SHA-256 (around 67% of the total 64 steps) and 46-step SHA-512 (around 57.5% of the total 80 steps), which significantly increases the number of attacked steps compared to the best previously published preimage attack working for 24 step...

  1. Adsorption dynamics of gases and vapors on the nanoporous metal organic framework material Ni2(4,4'-bipyridine)3(NO3)4: guest modification of host sorption behavior.

    Science.gov (United States)

    Fletcher, A J; Cussen, E J; Prior, T J; Rosseinsky, M J; Kepert, C J; Thomas, K M

    2001-10-17

    This study combines measurements of the thermodynamics and kinetics of guest sorption with powder X-ray diffraction measurements of the nanoporous metal organic framework adsorbent (host) at different adsorptive (guest) loadings. The adsorption characteristics of nitrogen, argon, carbon dioxide, nitrous oxide and ethanol and methanol vapors on Ni2(4,4'-bipyridine)3(NO3)4 were studied over a range of temperatures as a function of pressure. Isotherm steps were observed for both carbon dioxide and nitrous oxide adsorption at approximately 10-20% of the total pore volume and at approximately 70% of total pore volume for methanol adsorption. The adsorption kinetics obey a linear driving force (LDF) mass transfer model for adsorption at low surface coverage. At high surface coverage, both methanol and ethanol adsorption follow a combined barrier resistance/diffusion model. The rates of adsorption in the region of both the carbon dioxide and methanol isotherm steps were significantly slower than those observed either before or after the step. X-ray diffraction studies at various methanol loadings showed that the host structure disordered initially but underwent a structural change in the region of the isotherm step. These isotherm steps are ascribed to discrete structural changes in the host adsorbent that are induced by adsorption on different sites. Isotherm steps were not observed for ethanol adsorption, which followed a Langmuir isotherm. Previous X-ray crystallography studies have shown that all the sites are equivalent for ethanol adsorption on Ni2(4,4'-bipyridine)3(NO3)4, with the host structure undergoing a scissoring motion and the space group remaining unchanged during adsorption. The activation energies and preexponential factors for methanol and ethanol adsorption were calculated for each pressure increment at which the linear driving force model was obeyed. There was a good correlation between activation energy and ln(preexponential factor), indicating a

  2. Molecular Simulation of Hydrogen Adsorption Density in Single-Walled Carbon Nanotubes and Multilayer Adsorption Mechanism

    Institute of Scientific and Technical Information of China (English)

    Lianquan GUO; Changxiang MA; Shuai WANG; He MA; Xin LI

    2005-01-01

    The adsorption of hydrogen onto single-walled carbon nanotubes (SWCNTs) was studied by molecular dynamics (MD)sim.lation. It was found that the hydrogen molecules distribute regularly inside and outside of the tube. Density distribution was computed for H2 molecule. Theoretical analysis of the result showed the multilayer adsorption mechanism of SWCNTs. The storage of H2 in SWCNTs is computed, which provides essential theoretical reference for further study of hydrogen adsorption in SWCNTs.

  3. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

    2013-10-15

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

  4. Analysis of Modified Starch Adsorption Kinetics on Cellulose Fibers via the Modified Langmuir Adsorption Theory

    OpenAIRE

    Zakrajšek, N.; Knez, S.; Ravnjak, D.; Golob, J.

    2009-01-01

    The kinetics of starch adsorption on cellulose fibers is one of the most important criteria regarding the efficient application of papermaking additives due to the continuous nature of paper production and the concomitant need to determine optimum residence times. This study presents an analysis of the kinetics of modified starch adsorption onto cellulose fibers via the application of the modified Langmuir adsorption theory (i.e. the collision theory). A model based on this theory was used to...

  5. Adsorption equilibrium and dynamics of lactase/CM-Sephadex system

    OpenAIRE

    Harsa, Hayriye Şebnem; Göksungur, Yekta; Güvenç, Ulgar

    1995-01-01

    Partitioning behaviour and adsorption isotherms of lactase/CM-Sephadex system at equilibrium were investigated together with the adsorption kinetics in this study. Maximum adsorption was obtained at the pH values between 5.5–6.0. Adsorption isotherm was a close fit to the Langmuir model.

  6. Transoral Robotic Surgery: Step-by-Step Radical Tonsillectomy

    Directory of Open Access Journals (Sweden)

    Jose Granell

    2014-01-01

    Full Text Available Introduction. Transoral robotic surgery (TORS radical tonsillectomy is an emerging minimally invasive surgical procedure for the treatment of cancer of the tonsil. The detailed surgical technique and claims for its reproducibility have been previously published. Case Presentation. We present a patient with a T2N2bM0 epidermoid carcinoma of the tonsil to illustrate step by step the surgical procedure for TORS radical tonsillectomy. Neck dissection and TORS were staged. No surgical reconstruction of the defect was required. No tracheostomy was necessary. The patient could eat without any feeding tube and was on full oral diet on the fifth postoperative day. Discussion. The transoral approach offers the benefits of minimally invasive surgery to patients with cancer of the tonsil. The excellent exposure and high precision provided by robotic instrumentation allow the surgeon to closely follow and accomplish the surgical steps, which is the best warranty for safety and effectiveness.

  7. Adsorption of nisin and pediocin on nanoclays.

    Science.gov (United States)

    Meira, Stela Maris Meister; Jardim, Arthur Izé; Brandelli, Adriano

    2015-12-01

    Three different nanoclays (bentonite, octadecylamine-modified montmorillonite and halloysite) were studied as potential carriers for the antimicrobial peptides nisin and pediocin. Adsorption occurred from peptide solutions in contact with nanoclays at room temperature. Higher adsorption of nisin and pediocin was obtained on bentonite. The antimicrobial activity of the resultant bacteriocin-nanoclay systems was analyzed using skimmed milk agar as food simulant and the largest inhibition zones were observed against Gram-positive bacteria for halloysite samples. Bacteriocins were intercalated into the interlayer space of montmorillonites as deduced from the increase of the basal spacing measured by X-ray diffraction (XRD) assay. Infrared spectroscopy suggested non-electrostatic interactions, such as hydrogen bonding between siloxane groups from clays and peptide molecules. Transmission electron microscopy did not show any alteration in morphologies after adsorption of antimicrobial peptides on bentonite and halloysite. These results indicate that nanoclays, especially halloysite, are suitable nanocarriers for nisin and pediocin adsorption.

  8. Fluorocarbon Adsorption in Hierarchical Porous Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-09

    The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

  9. Adsorption Isotherms and Surface Reaction Kinetics

    Science.gov (United States)

    Lobo, L. S.; Bernardo, C. A.

    1974-01-01

    Explains an error that occurs in calculating the conditions for a maximum value of a rate expression for a bimolecular reaction. The rate expression is derived using the Langmuir adsorption isotherm to relate gas pressures and corresponding surface coverages. (GS)

  10. PREPARATION OF ACTIVATED CARBON FIBER AND THEIR XENON ADSORPTION PROPERTIES (Ⅱ)-XENON ADSORPTION PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The adsorption of xenon from air has an interest in the monitoring of nuclear explosion oraccident, or in the treatment of nuclear waste gas. In this paper, the pore structure of several series ofactivated carbon fibers has been characterized. The adsorption properties of xenon on theseactivated carbon fibers under different temperatures have been studied in details. The results showthat the xenon adsorption amount on activated carbon fibers do not increase with specific surfacearea of adsorbents, but are closely related to their pore size distribution. Pores whose radius equal toor narrow than 0.4nm would be more advantageous to the adsorption of xenon.

  11. Adsorption performances and refrigeration application of adsorption working pair of CaCl2-NH3

    Institute of Scientific and Technical Information of China (English)

    WANG; Liwei; WANG; Ruzhu; WU; Jingyi; WANG; Kai

    2004-01-01

    The adsorption performance of CaCl2-NH3 is studied under the condition of different expansion spaces for adsorbent, andthe relationships between adsorption performance of CaCl2-NH3 and the phenomena of swelling and agglomeration during adsorption are researched. It is found that the performance stability is related to the ratio of expansion space to the volume of adsorbent ras, and the performance attenuation is serious in the case of large ras. Severe adsorption hysteresis exists in the process of adsorption and desorption at the same evaporating and condensing temperatures, which is related to the stability constant of chemical reaction. This phenomenon cannot be explained by the theory of physical adsorption. Moderate agglomeration will be beneficial to the formation of ammoniate complex; the magnitude of expansion space will affect adsorption performance. Analysis shows that the activated energy needed in the process of adsorption for the sample with ras of 2:1 is less than that for the sample with ras of 3:1.The refrigeration performance of CaCl2-NH3 is predicted from experiments. The cooling capacity of one adsorption cycle is about 945.4 kJ/kg for the adsorbent with an ras of 2:1 at the evaporating temperature of 0℃.

  12. Partial return yoke for MICE step IV and final step

    International Nuclear Information System (INIS)

    This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

  13. Linear, Step by Step Managerial Performance, versus Exponential Performance

    Directory of Open Access Journals (Sweden)

    George MOLDOVEANU

    2011-04-01

    Full Text Available The paper proposes the transition from the potential management concept, which its authors approached by determining its dimension (Roşca, Moldoveanu, 2009b, to the linear, step by step performance concept, as an objective result of management process. In this way, we “answer” the theorists and practitioners, who support exponential management performance. The authors, as detractors of the exponential performance, are influenced by the current crisis (Roşca, Moldoveanu, 2009a, by the lack of organizational excellence in many companies, particularly in Romanian ones and also reaching “the finality” in the evolved companies, developed into an uncontrollable speed.

  14. Partial Return Yoke for MICE Step IV and Final Step

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Holger [Brookhaven; Plate, Stephen [Brookhaven; Berg, J.Scott [Brookhaven; Tarrant, Jason [Rutherford; Bross, Alan [Fermilab

    2015-06-01

    This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

  15. Partial return yoke for MICE step IV and final step

    Energy Technology Data Exchange (ETDEWEB)

    Witte, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Plate, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tarrant, J. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL); Bross, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-05-03

    This paper reports on the progress of the design and construction of a retro-fitted return yoke for the international Muon Ionization Cooling Experiment (MICE). MICE is a proof-of-principle experiment aiming to demonstrate ionization cooling experimentally. In earlier studies we outlined how a partial return yoke can be used to mitigate stray magnetic field in the experimental hall; we report on the progress of the construction of the partial return yoke for MICE Step IV. We also discuss an extension of the Partial Return Yoke for the final step of MICE; we show simulation results of the expected performance.

  16. Writing a Simulation Scenario: A Step-By-Step Guide.

    Science.gov (United States)

    Bambini, Deborah

    2016-02-01

    Simulation is becoming a widely used method of helping nurses learn and maintain competency in the clinical area for both staff educators in clinical settings and nursing faculty in academic settings. Designing an effective simulation experience requires thoughtful planning, knowledge of educational principles, and knowledge of best practices in both simulation and clinical practice. An evidence-based strategy for writing a simulation scenario for nurses and other health care providers in any setting is described. A step-by-step process is outlined that incorporates best practices. Examples and suggestions are provided to help readers create quality simulation experiences.

  17. Microsoft Office SharePoint Designer 2007 Step by Step

    CERN Document Server

    Coventry, Penelope

    2008-01-01

    The smart way to learn Office SharePoint Designer 2007-one step at a time! Work at your own pace through the easy numbered steps, practice files on CD, helpful hints, and troubleshooting tips to master the fundamentals of building customized SharePoint sites and applications. You'll learn how to work with Windows® SharePoint Services 3.0 and Office SharePoint Server 2007 to create Web pages complete with Cascading Style Sheets, Lists, Libraries, and customized Web parts. Then, make your site really work for you by adding data sources, including databases, XML data and Web services, and RSS fe

  18. Microsoft® Office Access™ 2007 Step by Step

    CERN Document Server

    Lambert, Steve; Lambert, Joan

    2009-01-01

    Experience learning made easy-and quickly teach yourself how to build database solutions with Access 2007. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them! Build databases from scratch or from templatesExchange data with other databases and Office documentsCreate forms to simplify data entryUse filters and queries to find and analyze informationDesign rich reports that help make your data meaningfulHelp prevent data corruption and unauthorized access Your all-in-one learning experience includes: Files for building skills and practic

  19. Information marketing business entrepreneur's step-by-step startup guide

    CERN Document Server

    magazine, Entrepreneur

    2012-01-01

    A six-figure income from information? Yes! It sounds easy because it is. You've got information that millions of others are looking for and now you can learn how to package, price and sell it.The experts at Entrepreneur take you step by step, jumpstarting your thinking about your area of expertise and showing you how to convert it into a high-demand information product. Following the example set by today's most successful information marketers, you learn the ins and outs of running your own information marketing business using proven strategies and effective marketing techniques.

  20. Selective adsorption of tannins onto hide collagen fibres

    Institute of Scientific and Technical Information of China (English)

    LIAO; Xuepin(廖学品); LU; Zhongbing(陆忠兵); SHI; Bi(石碧)

    2003-01-01

    Hide collagen of animals is used to prepare adsorbent material and its adsorption properties to tannins are investigated. It is indicated that the collagen fibres has excellent adsorption selectivity and high adsorption capacity to tannins. The adsorption rate of tannins is more than 90% whilst less than 10% of functional components are retained by the adsorbent. The adsorption mechanism of tannins onto hide collagen fibres is hydrogen-bonding association. Freundlich model can be used to describe the adsorption isotherms, and the pseudo-second-order rate model can be used to describe adsorption kinetics.

  1. Graphene oxide and adsorption of chloroform: a density functional study

    CERN Document Server

    Kuisma, Elena; Lindberg, Th Benjamin; Gillberg, Christoffer A; Idh, Sebastian; Schroder, Elsebeth

    2016-01-01

    Chlorinated hydrocarbon compounds are of environmental concerns, since they are toxic to humans and other mammals, are widespread, and exposure is hard to avoid. Understanding and improving methods to reduce the amount of the substances is important. We present an atomic-scale calculational study of the adsorption of chlorine-based substance chloroform (CHCl3) on graphene oxide, as a step in estimating the capacity of graphene oxide for filtering out such substances, e.g., from drinking water. The calculations are based on density functional theory (DFT), and the recently developed consistent-exchange functional for the van der Waals density-functional method (vdW-DF-cx) is employed. We obtain values of the chloroform adsorption energy varying from roughly 0.2 to 0.4 eV per molecule. This is comparable to previously found results for chloroform adsorbed directly on clean graphene, using similar calculations. In a wet environment, like filters for drinking water, the graphene will not stay clean and will likel...

  2. Adsorption properties of nitrobenzene in wastewater with silica aerogels

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The adsorption properties of nitrobenzene from wastewater by hydrophobic silica aerogels were investigated.The effects of adsorption intensity by pH value,adsorption temperature,adsorption time and the amount of the silica aerogels were studied.The adsorption principle and mechanism of silica aerogels adsorbing nitrobenzene were discussed along with the Freundlich equation.The results showed that the adsorption intensity of the hydrophobic silica aerogels could reach 68.76% at better adsorption conditions of adsorption temperature 25°C,pH value 8.35,the amount of SiO2 aerogels dosage 3.33 g/L,and adsorption time of 30 min,and that the adsorption properties were related to the hydrophobility of aerogels,surface area of organic solution,structure of aerogels.

  3. Adsorption Characteristics of Remazol Black B on Anoxic Sludge

    Institute of Scientific and Technical Information of China (English)

    HUANG Man-hong; CHEN Liang; CHEN Dong-hui; CHEN Chao-peng

    2009-01-01

    The adsorption characteristics of Remazol Black B on anoxic sludge were investigated. The parameters, such as initial pH, sulphate concentration, and temperature,affecting the dye adsorption were studied. The adsorption data were analyzed with three adsorption isotherm models,namely Langmuir, Freudlich, and linear partition. The results showed that adsorption of Remazol Black B on the sterilized sludge reached equilibrium in 4 h. It also indicated that pH had significant effect on anoxic sludge adsorption behavior. The adsorption capacity of anoxic sludge decreased with the increase of pH value and the maximum adsorption capacity of dyes occurred at pH = 3. The adsorptive capacities increased with the decrease of temperature and increase of sulphate concentration. Results also indicated that the adsorption equilibrium of Remazol Black B on anoxic sludge could be well fitted by Freundlich model.

  4. ADSORPTION OF LDL ON THE MODIFIED CHITOSAN

    Institute of Scientific and Technical Information of China (English)

    LIUManying; ZHAOLirui; 等

    2000-01-01

    In this paper,the selective adsorption of LDL on chitosan modified with PEG and Asp.was studied.The adsorption rate of LDL and HDL on the double modified chitosan was 57% and 12% respoectively,The results shown that the double modified chitosan can be used a adsorbent for selective binding to LDL,this work may help to develop functional columns for hemoperfusion.

  5. Adsorption Kinetic of 8-Hydroxyquinoline on Malachite

    Directory of Open Access Journals (Sweden)

    Gabriela OPREA

    2007-01-01

    Full Text Available Influence of temperature and collector concentration on its adsorption rate on mineral surface was studied as regarding to the 8-hydroxyquinoline/malachite system. Theoretical equations as well as experimental data may be useful to estimate the adsorption rate and kinetics connected to the conditioning stage in mineral flotation in order to optimise the selectivity and the recovery of the desired mineral.

  6. Defluoridation of drinking water using adsorption processes

    International Nuclear Information System (INIS)

    Highlights: ► Comprehensive and critical literature review on various adsorbents used for defluoridation. ► pH, temperature, kinetics and co-existing anions effects on F adsorption. ► Choice of adsorbents for various circumstances. ► Adsorption thermodynamics and mechanisms. ► Future research on efficient, low cost adsorbents which are easily regenerated. -- Abstract: Excessive intake of fluoride (F), mainly through drinking water, is a serious health hazard affecting humans worldwide. There are several methods used for the defluoridation of drinking water, of which adsorption processes are generally considered attractive because of their effectiveness, convenience, ease of operation, simplicity of design, and for economic and environmental reasons. In this paper, we present a comprehensive and a critical literature review on various adsorbents used for defluoridation, their relative effectiveness, mechanisms and thermodynamics of adsorption, and suggestions are made on choice of adsorbents for various circumstances. Effects of pH, temperature, kinetics and co-existing anions on F adsorption are also reviewed. Because the adsorption is very weak in extremely low or high pHs, depending on the adsorbent, acids or alkalis are used to desorb F and regenerate the adsorbents. However, adsorption capacity generally decreases with repeated use of the regenerated adsorbent. Future research needs to explore highly efficient, low cost adsorbents that can be easily regenerated for reuse over several cycles of operations without significant loss of adsorptive capacity and which have good hydraulic conductivity to prevent filter clogging during the fixed-bed treatment process

  7. Nitrate Adsorption on Clay Kaolin: Batch Tests

    Directory of Open Access Journals (Sweden)

    Morteza Mohsenipour

    2015-01-01

    Full Text Available Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

  8. Adsorption of xenon and krypton on shales

    International Nuclear Information System (INIS)

    Parameters for the adsorption of Xe and Kr on shales and related samples have been measured by a method that uses a mass spectrometer as a manometer. The gas partial pressures used were 10-11 atm or less; the corresponding adsorption coverages are only small fractions of a monolayer, and Henry's Law behavior is expected and observed. Heats of adsorption in the range 2 to 7 kcal/mol were observed. Henry constants of the order of magnitude 1 cm3 STP g-1 atm-1 at 0 to 250C are obtained by extrapolation. Adsorption properties are variable by sample, but the general range suggests that shales might be sufficiently good adsorbents that equilibrium adsorption with modern air may account for a nontrivial fraction of the atmospheric inventory of Xe (perhaps even Kr). It seems doubtful, however, that this effect can account for the deficiency of atmospheric Xe in comparison with the planetary gas patterns observed in meteorites. If gas is adsorbed on interior surfaces in shale clays and can communicate with sample exteriors only through very narrow channels, and thus only very slowly, equilibrium adsorption may make substantial contributions to experimentally observed 'trapped' gases without the need for any further trapping mechanism. (author)

  9. Modeling of Experimental Adsorption Isotherm Data

    Directory of Open Access Journals (Sweden)

    Xunjun Chen

    2015-01-01

    Full Text Available Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained by batch tests in lab. The linearized and non-linearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the correlation coefficient (r2 and standard errors (S.E. for each parameter were used to evaluate the data. The modeling results showed that non-linear Langmuir model could fit the data better than others, with relatively higher r2 values and smaller S.E. The linear Langmuir model had the highest value of r2, however, the maximum adsorption capacities estimated from linear Langmuir model were deviated from the experimental data.

  10. Adsorption of mercury ions by mercapto-functionalized amorphous silica

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Quintanilla, Damian; Hierro, Isabel del; Fajardo, Mariano; Sierra, Isabel [Universidad Rey Juan Carlos, Departamento de Tecnologia Quimica y Ambiental, E.S.C.E.T, Mostoles, Madrid (Spain); Carrillo-Hermosilla, Fernando [Universidad de Castilla-La Mancha, Departamento de Quimica Inorganica, Organica y Bioquimica, Facultad de Quimicas, Ciudad Real (Spain)

    2006-02-01

    Amorphous silicas have been functionalized by two different methods. In the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the silica surface to give the chlorinated silica Cl-Sil. In a second reaction, multifunctionalized N,S donor compounds were incorporated to obtain the functionalized silicas, which are denoted as L-Sil-Het (where L=mercaptothiazoline, mercaptopyridine or mercaptobenzothiazole). In the homogeneous route, the functionalization was achieved through a one-step reaction between the silica and an organic ligand containing the chelating functions; this gave the modified silicas denoted as L-Sil-Hom. The functionalized silicas were characterized by elemental analysis, IR spectroscopy and thermogravimetry. These materials were employed as adsorbents for mercury cations from aqueous and acetone solutions at room temperature. The results indicate that, in all cases, mercury adsorption was higher in the modified silicas prepared by the homogeneous method. (orig.)

  11. Cataloging Books Step by Step. CSLA Guide No. 5.

    Science.gov (United States)

    Smith, Ruth S.

    Designed as a beginning, how-to guide, this handbook lists 20 short steps to cataloging library materials for a church or synagogue library. The guide opens with a history and a brief explanation of the Dewey Decimal System, with special attention given to the divisions and subdivisions that fall under the category "Religion." Several references…

  12. Writing the Winning Dissertation: A Step-By-Step Guide.

    Science.gov (United States)

    Glatthorn, Allan A.

    This book is a practical guide to researching and writing the doctoral dissertation or master's thesis. Part 1 offers seven chapters on preparatory steps: laying the groundwork for the thesis and dissertation; finding a research problem; conducting a focused review of the literature; making a preliminary choice of methodology; organizing and…

  13. Single-step Purification of Molecular Chaperone GroEL by Expanded Bed Chromatography

    Institute of Scientific and Technical Information of China (English)

    佟晓冬; 杨征; 董晓燕; 孙彦

    2003-01-01

    Expanded bed adsorption (EBA) is an integrative downstream processing technique for the purification of biological substances directly from unclarified feedstock. In this study, molecular chaperone GroEL, an important protein folding helper both in vivo and in vitro, was purified by the single-step EBA technique from the unclarified homogenate of recombinant E. coli cells. Compared with packed bed adsorption, the EBA technique provided a single-step approach to yield an electrophoretic purity of GroEL. After the homogenate loading and column washing in the expanded bed mode, the GroEL protein was recovered by stepwise salt-gradient elution in packed-bed or expanded-bed modes, respectively. The expanded-bed elution mode was found as efficient as the packed-bed mode in the purification of GroEL from cell disruptate.

  14. [Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].

    Science.gov (United States)

    Liu, Juan-Juan; Liang, Dong-Li; Wu, Xiao-Long; Qu, Guang-Zhou; Qian, Xun

    2014-01-01

    The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu

  15. [Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].

    Science.gov (United States)

    Liu, Juan-Juan; Liang, Dong-Li; Wu, Xiao-Long; Qu, Guang-Zhou; Qian, Xun

    2014-01-01

    The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu

  16. Shapiro step at nonequilibrium conditions

    Science.gov (United States)

    Shukrinov, Yu. M.; Nashaat, M.; Kulikov, K. V.; Dawood, R.; El Samman, H.; El Sherbini, Th. M.

    2016-07-01

    Detailed numerical simulations of intrinsic Josephson junctions of high-temperature superconductors under external electromagnetic radiation are performed taking into account a charge imbalance effect. We demonstrate that the charge imbalance is responsible for a slope in the Shapiro step in the IV-characteristic. The value of slope increases with a nonequilibrium parameter. Coupling between junctions leads to the distribution of the slope's values along the stack. The nonperiodic boundary conditions shift the Shapiro step from the canonical position determined by Vss=\\hbar f /(2e) , where f is a frequency of external radiation. This fact makes the interpretation of the experimentally found Shapiro step shift by the charge imbalance effect ambiguous.

  17. Piezoelectric step-motion actuator

    Science.gov (United States)

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  18. Convex Optimization without Projection Steps

    CERN Document Server

    Jaggi, Martin

    2011-01-01

    We study the general problem of minimizing a convex function over a compact convex domain. We will investigate a simple iterative approximation algorithm that does not need projection steps in order to stay inside the optimization domain. Instead of a projection step, the linearized problem defined by a current subgradient is solved, which gives a step direction that will naturally stay in the domain. The approach generalizes the sparse greedy algorithm of Clarkson (and the low-rank SDP solver by Hazan) to arbitrary convex domains, and to using subgradients for the case of non-differentiable convex functions. Analogously, we give a convergence proof guaranteeing {\\epsilon}-small duality gap after O(1/{\\epsilon}) iterations. The framework allows us understand the sparsity of approximate solutions for any l1-regularized convex optimization problem, expressed as a function of the approximation quality. We obtain matching upper and lower bounds of {\\Theta}(1/{\\epsilon}) for the sparsity for l1-problems. The same ...

  19. Needed Computations Shortcutting Needed Steps

    DEFF Research Database (Denmark)

    Antoy, Sergio; Johannsen, Jacob; Libby, Steven

    We define a compilation scheme for a constructor-based strongly-sequential graph rewriting system which shortcuts some needed steps. The result of this compilation is another constructor-based graph rewriting system that is normalizing for the original system when using an innermost strategy. We...... then modify the resulting rewrite sytem in a way that avoids totally or partially the construction of the contracta of some needed steps of a computation. The resulting rewrite system can be easily implemented by eager functions in a variety of programming languages. When computing normal forms in this way...

  20. Web design in easy steps

    CERN Document Server

    McManus, Sean

    2011-01-01

    There are millions of websites on the Internet, but most of them fail to make a lasting impression on readers and web surfers. Creating a site that is both appealing and financially remunerative can seem challenging, but this invaluable tool makes the process both simple and fun. As with every book in the popular series of computer books, this one walks readers through every step of the process. From design planning to search engine promotion, each step of the process is thoroughly explained in clear, jargon-free English. Full-color graphics, including numerous screenshots, add further support

  1. Office 2010 in easy steps

    CERN Document Server

    Price, Michael

    2011-01-01

    In easy-to-understand, jargon-free language, Office 2010 in Easy Steps makes the task of learning this new version of Office easy and painless. Covering all the key features, this guide makes it simple to get up and running in no time. Here readers will learn the basics, as well as to master the updated customizable Ribbon, grasp the new Backstage full-screen options, learn how to use the new image and illustration tools, understand new Office web applications, and more. Office 2010 in Easy Steps combs through the new features and covers in detail all the ones that readers will use time and ti

  2. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Shuguang; LI Yanhui

    2004-01-01

    The properties and applications of CNT have been studied extensively since Iijima discovered them in 1991[1,2]. They have exceptional mechanical properties and unique electrical property, highly chemical stability and large specific surface area. Thus far, they have widely potential applications in many fields. They can be used as reinforcing materials in composites[3], field emissions[4], hydrogen storage[5], nanoelectronic components[6], catalyst supports[7], adsorption material and so on. However, the study on the potential application of CNT, environmental protection field in particular, was hardly begun.Long[8] et al. reported that CNT had a significantly higher dioxin removal efficiency than that of activated carbon. The Langmuir adsorption constant is 2.7 × 1052, 1.3 × 1018 respectively. The results indicated that CNT is potential candidate for the removal of micro-organic pollutants. However, the reports on the CNT used as fluoride and heavy metal adsorbent are seldom.In this paper, A novel material, alumina supported on carbon nanotubes (Al2O3/CNT), was prepared from carbon nanotubes and Al(NO3)3. X-ray diffraction (XRD) spectra demonstrate that alumina is amorphous, and scanning electron microscope (SEM) images show that CNT and alumina are homogeneously mixed. Furthermore, the fluoride adsorption behavior on the surface of Al2O3/CNT has been investigated and compared with other adsorbents. The results indicate that Al2O3/CNT has a high adsorption capacity, with a saturation adsorption capacity of 39.4 mg/g. It is also found that the adsorption capacity of Al2O3/CNT is 3.0~4.5 times that of γ-Al2O3while almost equal to that of IRA-410 polymeric resin at 25 ℃. The adsorption isotherms of fluoride on Al2O3/CNT is fit the Freundlich equation well, optimal pH ranging from 5.0 to 9.0.Also in this paper, a novel material, modified carbon nanotubes (CNT), was prepared from carbon nanotubes and HNO3 under boiling condition. Infrared spectroscopy (IR

  3. Adsorption of aqueous copper on peanut hulls

    Science.gov (United States)

    Davis, Kanika Octavia

    A method was established for measuring the adsorption of Cu(II) from aqueous solution to unmodified and modified peanut hulls at constant temperature and pH. Modification of the hulls was performed by oxidation with alkaline hydrogen peroxide. During the modification process, the hydrogen peroxide solubilizes the lignin component, making the surface more porous which increases the availability of binding sites, while simultaneously oxidizing the cellulose. The oxidation of alcohol groups creates more binding sites by creating functional groups such as COO-, which increases chelation to metal ions. Fourier transform infrared spectroscopy confirms delignification of the peanut hulls by the disappearance of carboxyl peaks of the modified hulls, which were originally produced from the lignin content. Although, oxidation is not fully confirmed, it is not ruled out because the expected carboxylate peak (1680 cm-1) maybe overshadowed by a broad peak due to OH bending of water adsorbed to the hulls. Hulls adsorbed copper from solutions in the concentration range of 50-1000 ppm of CuCl2. Concentrations of pre- and post-adsorption solutions were determined using inductively coupled plasma optical emission spectroscopy. The adsorption isotherms were fit to known two and three-parameter models, evaluated and the binding mechanism was inferred. Maximum surface coverage was 3.5 +/- 0.6 mg Cu2+ /g hull for unmodified hulls and 11 +/- 1 mg Cu2+/g hull for modified hulls. The adsorption for the hulls is best described by the Langmuir model, suggesting monolayer, homogeneous adsorption. With a free energy of adsorption of 10.5 +/- 0.9 kJ/mol for unmodified hulls and 14.5 +/-0.4 kJ/mol for modified hulls, the process is categorized as chemisorption for both types of hulls. The adsorption for both hulls is also described by the Redlich-Peterson model, giving beta nearer to 1 than 0, which further suggests homogeneous adsorption described by the Langmuir model. After rinsing the hulls

  4. THERMODYNAMIC STUDY OF HIGH-PRESSURE ADSORPTION OF METHANE AND HEATS OF METHANE ADSORPTION ON MICROPOROUS CARBONS

    Institute of Scientific and Technical Information of China (English)

    杨晓东; 林文胜; 郑青榕; 顾安忠; 鲁雪生; 宋燕

    2002-01-01

    The study was done for high-pressure adsorption of methane on microporous carbons, which has an ANG vehicular application background. Adsorption isotherm of methane on super activated carbon up to 6 MPa was measured and isosteric heats of methane adsorption on a number of microporous carbons were determined from adsorption isosteres by the Clausius-Clapeyron equation. The variation of the isosteric heats of adsorption with the amount of methane adsorbed was discussed.

  5. Adsorption of acid and basic dyes by sludge-based activated carbon:Isotherm and kinetic studies

    Institute of Scientific and Technical Information of China (English)

    李鑫; 王广智; 李伟光; 王萍; 宿程远

    2015-01-01

    A batch experiment was conducted to investigate the adsorption of an acid dye (Acid Orange 51) and a basic dye (Safranine) from aqueous solutions by the sludge-based activated carbon (SBAC). The results show that the adsorption of Acid Orange 51 decreases at high pH values, whereas the uptake of Safranine is higher in neutral and alkaline solutions than that in acidic conditions. The adsorption time needed for Safranine to reach equilibrium is shorter than that for Acid Orange 51. The uptakes of the dyes both increase with temperature increasing, indicating that the adsorption process of the dyes onto SBAC is endothermic. The equilibrium data of the dyes are both best represented by the Redlich−Peterson model. At 25 °C, the maximum adsorption capacities of SBAC for Acid Orange 51 and Safranine are 248.70 mg/g and 525.84 mg/g, respectively. The Elovich model is found to best describe the adsorption process of both dyes, indicating that the rate-limiting step involves the chemisorption. It can be concluded that SBAC is a promising material for the removal of Acid Orange 51 and Safranine from aqueous solutions.

  6. Comparative analysis of tropaeolin adsorption onto raw and acid-treated kaolinite: optimization by Response Surface Methodology.

    Science.gov (United States)

    de Sales, Priscila F; Magriotis, Zuy M; Rossi, Marco A L S; Resende, Ricardo F; Nunes, Cleiton A

    2015-03-15

    The comparative adsorption of Tropaeolin (TP) onto raw kaolinite (RK) and kaolinite submitted to acid treatment (AK) was studied. RK and AK were characterized by zeta potential and energy dispersive X-ray spectroscopy (EDS). The adsorption was investigated using Composite Central Design (CCD) and the parameters evaluated were initial TP solution concentration, quantity of adsorbent and the pH of the solution. The optimized parameters were: initial TP solution concentration of 75 mg L(-1), pH 4 and 0.12 g adsorbent. Kinetic data were evaluated by pseudo-first order, pseudo-second order and Avrami models. The equilibrium adsorption was analyzed by Langmuir, Freundlich and Sips isotherms. The kinetic data were best fitted to the pseudo-second order model. The Sips isotherm model gives the better correlation to predict the adsorption equilibrium. The maximum adsorption capacities were 18.3 mg g(-1) and 23.2 mg g(-1) for RK and AK, respectively. The calculated thermodynamic parameters showed that the process was spontaneous, endothermic and involving the disorganization of the adsorption system for both adsorbents. The desorption step showed that the AK sample was more suitable as an adsorbent. PMID:25559496

  7. Equilibrium and kinetic study for the adsorption of p-nitrophenol from wastewater using olive cake based activated carbon

    Directory of Open Access Journals (Sweden)

    N.T. Abdel-Ghani

    2016-01-01

    Full Text Available The present work was carried out to evaluate the removal of p-nitrophenol by adsorption onto olive cake based activated carbon having a BET surface area of 672 m²/g. The batch adsorption experimental results indicated that the equilibrium time for nitrophenol adsorption by olive cake-based activated carbon was 120min. The adsorption data was modeled by equilibrium and kinetic models. The pseudo- first and second order as well as the Elovichkinetic models were applied to fit the experimental data and the intraparticle diffusion model was assessed for describing the mechanism of adsorption. The data were found to be best fitted to the pseudo-second order model with a correlation coefficient (R2=0.986. The intraparticle diffusion mechanism also showed a good fit to the experimental data, showing two distinct linear parts assuming that more than one step could be involved in the adsorption of nitrophenol by the activated carbon. The equilibrium study was performed using three models including Langmuir, Freundlich and Temkin. The results revealed that the Temkin equilibrium model is the best model fitting the experimental data (R2=0.944. The results of the present study proved the efficiency of using olive cake based activated carbon as a novel adsorbent for the removal of nitrophenol from aqueous solution.

  8. SYNTHESIS AND CHARACTERIZATIONOF ORGANIC FUNCTIONALIZED MESOPOROUS SILICA AND EVALUATE THEIR ADSORPTIVE BEHAVIOR FOR REMOVAL OF METHYLENE BLUE FROM AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    Sameer H. Kareem

    2014-01-01

    Full Text Available Three Mesoporous Silica (MPS with different functional groups were prepared by one-step synthesis based on the simultaneous hydrolysis and condensation of tetraethoxy silane with organo-silane in the presence of template surfactant Polydimethylsiloxane-Polyethyleneoxide (PDMS-PEO. The prepared materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR, Thermogravimetric Analysis (TGA and nitrogen adsorption-desorption experiments. The results indicate that the preparation of methyl and phenyl functionalized silica were successful. The adsorption behavior of methylene blue from aqueous systems onto these mesoporous silica has been studied. Batch experiments were carried out to measure the adsorption as a function of contact time, initial concentration (2.5-20 mg L-1 and temperature (288, 298, 308 and 318 K. The equilibrium of the process was achieved within (30-60 min. The adsorption of methylene blue on the mesoporous silica increases with increasing temperature which indicating an endothermic process. Adsorption isotherms were fitted with the Langmuir, Freundlich models. The kinetic data were analyzed using pseudo-first- order and pseudo-second-order models and intraparticle diffusion. The adsorption kinetics of methylene blue on mesoporous silica matched well with pseudo-second order kinetic model.

  9. Adsorption of textile reactive dyestuffs by treatment sludges of inorganic nature.

    Science.gov (United States)

    Tünay, Olcay; Metin, Emine; Olmez-Hanci, Tuğba; Kabdaşli, Işik

    2012-01-01

    Colour removal from industrial effluents, particularly from the textile industry, has become an important requirement as the adverse effects ofdyestuffs, such as toxicity, on the environment have been proven. Adsorption is a commonly used treatment method for colour removal. Although activated carbon is very effective for this purpose, a number of natural materials and waste materials, such as waste sludges generated from treatment systems, have been tested to reduce the cost of the process. In this paper, sludges arising from the operation of an electrocoagulation process that used stainless steel or aluminium electrodes were investigated as adsorbents for decolorization of reactive dyestuffs. Electrocoagulation waste sludges produced with the use of stainless steel electrodes provided higher than 90% or complete decolorization of Crimson HEXL, Yellow HE4R and RB5 dyestuffs. The sludge produced with aluminium electrodes yielded colour adsorption between 95% and 100% at a 1 g/L dose and pH 8.5-9.1 for two of the dyestuffs; the removal of RB5 did not exceed 60% up to a 4.76 g/L dose. FeCl3 coagulation and adsorption using freshly precipitated coagulation sludge resulted in poor colour removals of 10% for all three dyestuffs. The superior colour adsorption performance of electrocoagulation waste sludges was attributed to modification of the surface properties of the sludges during the electrocoagulation operation. A batch-wise kinetic study indicated that the adsorption of RB5 on to electrocoagulation waste sludges was well fitted by the pseudo-second-order kinetic model, suggesting the intra-particle diffusion process as the rate-limiting step of the adsorption process.

  10. Petroleum coke adsorption as a water management option for oil sands process-affected water

    Energy Technology Data Exchange (ETDEWEB)

    Zubot, Warren [Syncrude Canada Ltd., Research and Development, Edmonton, Alberta, Canada T6N 1H4 (Canada); MacKinnon, Michael D. [OSPM Solutions Ltd., Hamilton, Ontario, Canada L8H 6X2 (Canada); Chelme-Ayala, Pamela; Smith, Daniel W. [University of Alberta, Department of Civil and Environmental Engineering, Edmonton, Alberta, Canada T6G 2W2 (Canada); Gamal El-Din, Mohamed, E-mail: mgamalel-din@ualberta.ca [University of Alberta, Department of Civil and Environmental Engineering, Edmonton, Alberta, Canada T6G 2W2 (Canada)

    2012-06-15

    Water is integral to both operational and environmental aspects of the oil sands industry. A water treatment option based on the use of petroleum coke (PC), a by-product of bitumen upgrading, was examined as an opportunity to reduce site oil sands process-affected water (OSPW) inventories and net raw water demand. Changes in OSPW quality when treated with PC included increments in pH levels and concentrations of vanadium, molybdenum, and sulphate. Constituents that decreased in concentration after PC adsorption included total acid-extractable organics (TAO), bicarbonate, calcium, barium, magnesium, and strontium. Changes in naphthenic acids (NAs) speciation were observed after PC adsorption. A battery of bioassays was used to measure the OSPW toxicity. The results indicated that untreated OSPW was toxic towards Vibrio fischeri and rainbow trout. However, OSPW treated with PC at appropriate dosages was not acutely toxic towards these test organisms. Removal of TAO was found to be an adsorption process, fitting the Langmuir and Langmuir-Freundlich isotherm models. For TAO concentrations of 60 mg/L, adsorption capacities ranged between 0.1 and 0.46 mg/g. This study demonstrates that freshly produced PC from fluid cokers provides an effective treatment of OSPW in terms of key constituents' removal and toxicity reduction. - Highlights: Black-Right-Pointing-Pointer Treatment of oil sands process-affected water (OSPW) using petroleum coke (PC) adsorption was investigated. Black-Right-Pointing-Pointer PC was effective at adsorbing naphthenic acids with higher cyclicity. Black-Right-Pointing-Pointer OSPW treated with PC at appropriate dosages was not toxic towards Vibrio fisheri and rainbow trout. Black-Right-Pointing-Pointer The adsorption of organic acids fitted the Langmuir and Langmuir-Freundlich isotherm models. Black-Right-Pointing-Pointer PC has the potential to be an effective adsorbent to treat OSPW either directly or as a pretreatment step.

  11. A review of the thermodynamics of protein association to ligands, protein adsorption, and adsorption isotherms

    DEFF Research Database (Denmark)

    Mollerup, Jørgen

    2008-01-01

    The application of thermodynamic models in the development of chromatographic separation processes is discussed. The paper analyses the thermodynamic principles of protein adsorption. It can be modeled either as a reversible association between the adsorbate and the ligands or as a steady...... of adsorption is discussed. Hydrophobic and reversed phase chromatography are useful techniques for measuring solute activity coefficients at infinite dilution....

  12. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

    Science.gov (United States)

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    2013-10-01

    Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. PMID:23684695

  13. Heavy metal adsorption changes of EAF steel slag after phosphorus adsorption.

    Science.gov (United States)

    Song, Guanling; Cao, Lijing; Chen, Xiao; Hou, Wenhua; Wang, Qunhui

    2012-01-01

    A kind of electric arc furnace (EAF) steel slag was phosphated, and its isothermal and dynamic adsorptions of copper, cadmium, and lead ions were measured to determine if heavy metal adsorption changes after phosphorus adsorption. The surface area increased greatly after the slag was phosphated. Isothermal adsorption experiments showed that the theoretical Q(max) of the EAF steel slag on Cu(2+), Cd(2+), and Pb(2+) improved 59, 50, and 89% respectively after it was phosphated. Dynamic adsorption results showed that the greatest adsorption capacities of unit volume of Cu(2+), Cd(2+), and Pb(2+) were 2.2, 1.8, and 1.8 times that of the column packed with original EAF steel slag when the column was packed with phosphate EAF steel slag at the same heavy metal ion concentration. The breakthrough time, the exhaustion time and elution efficiency of the column also increased when the column was packed with phosphated EAF steel slag compared with that packed with original EAF steel slag. Phosphorus adsorption could further improve the heavy metal ion adsorption of the EAF steel slag.

  14. Initial steps of aerosol growth

    Directory of Open Access Journals (Sweden)

    O. Kulmala

    2004-09-01

    Full Text Available The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent – mainly condensational – growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhance growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  15. Initial steps of aerosol growth

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2004-01-01

    Full Text Available The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent – mainly condensational – growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  16. Initial steps of aerosol growth

    Science.gov (United States)

    Kulmala, M.; Laakso, L.; Lehtinen, K. E. J.; Riipinen, I.; Dal Maso, M.; Anttila, T.; Kerminen, V.-M.; Hõrrak, U.; Vana, M.; Tammet, H.

    2004-12-01

    The formation and growth of atmospheric aerosols depend on several steps, namely nucleation, initial steps of growth and subsequent - mainly condensational - growth. This work focuses on the initial steps of growth, meaning the growth right after nucleation, where the interplay of curvature effects and thermodynamics has a significant role on the growth kinetics. More specifically, we investigate how ion clusters and aerosol particles grow from 1.5 nm to 20 nm (diameter) in atmospheric conditions using experimental data obtained by air ion and aerosol spectrometers. The measurements have been performed at a boreal forest site in Finland. The observed trend that the growth rate seems to increase as a function of size can be used to investigate possible growth mechanisms. Such a growth rate is consistent with a recently suggested nano-Köhler mechanism, in which growth is activated at a certain size with respect to condensation of organic vapors. The results also imply that charge-enhanced growth associated with ion-mediated nucleation plays only a minor role in the initial steps of growth, since it would imply a clear decrease of the growth rate with size. Finally, further evidence was obtained on the earlier suggestion that atmospheric nucleation and the subsequent growth of fresh nuclei are likely to be uncoupled phenomena via different participating vapors.

  17. Step sites in syngas catalysis

    DEFF Research Database (Denmark)

    Rostrup-Nielsen, J.; Nørskov, Jens Kehlet

    2006-01-01

    Step sites play an important role in many catalytic reactions. This paper reviews recent results on metal catalysts for syngas reactions with emphasis on steam reforming. Modern characterization techniques (STEM, HREM...) and theoretical calculations (DFT) has allowed a more quantitative explanat...

  18. 10 Steps for Implementing Change.

    Science.gov (United States)

    Marsee, Jeff

    2002-01-01

    Offers steps for adapting the change process to institutional culture: align leadership style with organizational culture, don't overuse change missionaries, protect change agents, define the problem, maintain focus when the project drifts, identify and remove barriers before implementing action plans, assign responsibilities to individuals,…

  19. Ten Steps to "TQM Plus."

    Science.gov (United States)

    Kaufman, Roger; Hirumi, Atsusi

    1992-01-01

    Total Quality Management Plus (TQM) goes beyond customer satisfaction to consider quality of life, environmental conditions, crime rates, and health and well-being. Steps to integrate such concerns into the TQM process include being ready for challenges, creating a quality system to collect performance data, defining the ideal school and world…

  20. Monte Carlo Simulations of the Adsorption of Anisotropic Noninteracting Molecules on the (111) Surface of a FCC Crystal

    Science.gov (United States)

    Filimonov, S. N.; Hervieu, Yu. Yu.

    2016-04-01

    We present results of computer Monte Carlo simulations of the formation of adsorption layers composed of noninteracting molecules of benzene, anthracene, and pentacene on the Ag(111) surface. The dependences of the chemical potential of the molecules on the density of the molecular layer (surface coverage) are obtained. By means of the thermodynamic integration method the configurational entropy of the molecular layer is evaluated as a function of surface coverage. It is shown that the substitution of benzene by pentacene results in a more than twofold decrease of the maximum entropy of the molecular layer. The presence of steps on the substrate surface also leads to a decrease of the molecular layer entropy. If the distance between the steps is comparable to the linear size of the molecule, the molecules in dense adsorption layers orient preferentially parallel to the step edges.

  1. Adsorption of zinc on manganite (γ-MnOOH):particle concentration effect and adsorption reversibility

    Institute of Scientific and Technical Information of China (English)

    QIN Yan-wen; PAN Gang; ZHANG Ming-ming; LI Xian-liang

    2004-01-01

    The adsorption and desorption processes of Zn(Ⅱ) on γ-MnOOH as a function of particle concentrations (Cp) were studied. An obvious Cp effect was observed in this adsorption system. The degree of adsorption hysteresis increased greatly with the increasing of Cp, indicating that the extent of the real metastable-equilibrium states deviating from the ideal equilibrium state was enhanced with the increasing of Cp. The Cp-reversibility relationship confirmed the metastable-equilibrium adsorption (MEA) inequality (Pan, 1998a), which was the core formulation of the MEA theory. Because the MEA inequality was based on the basic hypothesis of MEA theory that adsorption density Г is not a state variable, the Cp-reversibility relationship gave indirect evidence to the basic hypothesis of MEA theory.

  2. Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    Science.gov (United States)

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2005-12-13

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  3. Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

    Science.gov (United States)

    Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

    2003-10-07

    The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

  4. Conceptual adsorption models and open issues pertaining to performance assessment

    International Nuclear Information System (INIS)

    Recently several articles have been published that question the appropriateness of the distribution coefficient, Rd, concept to quantify radionuclide migration. Several distinct issues surrounding the modeling of nuclide retardation. The first section defines adsorption terminology and discusses various adsorption processes. The next section describes five commonly used adsorption conceptual models, specifically emphasizing what attributes that affect adsorption are explicitly accommodated in each model. I also review efforts to incorporate each adsorption model into performance assessment transport computer codes. The five adsorption conceptual models are (1) the constant Rd model, (2) the parametric Rd model, (3) isotherm adsorption models, (4) mass action adsorption models, and (5) surface-complexation with electrostatics models. The final section discusses the adequacy of the distribution ratio concept, the adequacy of transport calculations that rely on constant retardation factors and the status of incorporating sophisticated adsorption models into transport codes. 86 refs., 1 fig., 1 tab

  5. Competitive adsorption of heavy metal ions on peat

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-rong; ZHOU Li-min; WEI Peng; ZENG Kai; WEN Chuan-xi; LAN Hui-hua

    2008-01-01

    The uptake capacities, and the adsorption kinetics, of copper, Cu(Ⅱ), nickel, Ni(Ⅱ), and cadmium, Cd(Ⅱ), on peat have been studied under static conditions. The results show that the adsorption rates are rapid: equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacifies follow the order Cu2+>Ni2+>Cd2+ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu2+> Ni2+>Cd2+ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.

  6. Adsorption behavior of molybdenum onto D314 ion exchange resin

    Institute of Scientific and Technical Information of China (English)

    王明玉; 蒋长俊; 王学文

    2014-01-01

    The adsorption behavior of molybdenum onto D314 was studied with the static adsorption method. The adsorption process was analyzed from thermodynamic and kinetic aspects. The experimental results show that the equilibrium adsorption data conform satisfactorily to the Langmuir equation. In the adsorption process of D314 for molybdenum, the enthalpy changeΔH is positive when temperature is in the range of 298−338 K, which indicates that the adsorption is an endothermic process, and the elevated temperature benefits to the adsorption. Kinetic analysis shows that the adsorption rate is controlled by intraparticle diffusion and chemical diffusion at the same time. The adsorption mechanism of molybdenum onto D314 was discussed based on IR spectra.

  7. Conceptual adsorption models and open issues pertaining to performance assessment

    International Nuclear Information System (INIS)

    Recently several articles have been published that question the appropriateness of the distribution coefficient, Rd, concept to quantify radionuclide migration. Several distinct issues are raised by various critics. In this paper I provide some perspective on issues surrounding the modeling of nuclide retardation. The first section defines adsorption terminology and discusses various adsorption processes. The next section describes five commonly used adsorption conceptual models, specifically emphasizing what attributes that affect adsorption are explicitly accommodated in each model. I also review efforts to incorporate each adsorption model into performance assessment transport computer codes. The five adsorption conceptual models are (1) the constant Rd model, (2) the parametric Rd model, (3) isotherm adsorption models, (4) mass-action adsorption models, and (5) surface-complexation with electrostatics models. The final section discusses the adequacy of the distribution ratio concept, the adequacy of transport calculations that rely on constant retardation factors and the status of incorporating sophisticated adsorption models into transport codes

  8. Tungsten removal from molybdate solutions using chelating ion-exchange resin:Equilibrium adsorption isotherm and kinetics

    Institute of Scientific and Technical Information of China (English)

    朱先正; 霍广生; 倪捷; 宋琼

    2016-01-01

    The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na2MoO4 and Na2WO4 solutions. The sorption isotherm results show that the adsorption process of W obeys the Freundlich model very well whereas the exchange process with Mo approximately follows the Henry model. The kinetic experiments show that the intraparticle diffusion process was the rate-determining step for W sorption on the resin, and the corresponding activation energy is calculated to be 21.976 kJ/mol.

  9. Selective adsorption of cationic dyes from aqueous solution by polyoxometalate-based metal-organic framework composite

    Science.gov (United States)

    Liu, Xiaoxia; Gong, Wenpeng; Luo, Jing; Zou, Chentao; Yang, Yun; Yang, Shuijin

    2016-01-01

    A novel environmental friendly adsorbent H6P2W18O62/MOF-5 was synthesized by a simple one-step reaction under solvothermal conditions and characterized by XRD, FTIR, thermogravimetric analyses (TGA) and N2 adsorption-desorption isotherms. The removal rate of H6P2W18O62/MOF-5 was quite greater (85%) than that of MOF-5 (almost zero), showing that the adsorption performance of porous MOF-5 can be improved through the modification of H6P2W18O62. Further study revealed that H6P2W18O62/MOF-5 exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes in aqueous solution. The removal rate was up to 97% for cationic dyes methylene blue (MB) and 68% for rhodamine B(Rhb) within 10 min. However, anionicdye methyl orange(MO) can only reach to 10%. The influences including initial concentration, contact time, initial solution pH and temperature of MB adsorption onto H6P2W18O62/MOF-5 were investigated in detail. The kinetic study indicated that the adsorption of MB onto H6P2W18O62/MOF-5 followed the pseudo second-order model well. The isotherm obtained from experimental data fitted the Langmuir model, yielding maximum adsorption capacity of 51.81 mg/g. The thermodynamic parameters analysis illustrated that the MB adsorption onto H6P2W18O62 immobilized MOF-5 was spontaneous and endothermic process. Besides, these results implied that designing a novel material polyoxometalate-based metal-organic frameworks is great potential for removing cationic organic pollutants and even extended to improve other specific application.

  10. Adsorption Behavior and Mechanism of Antibiotic Sulfamethoxazole on Carboxylic-Functionalized Carbon Nanofibers-Encapsulated Ni Magnetic Nanoparticles.

    Science.gov (United States)

    Lan, Yi K; Chen, Tse C; Tsai, Hsing J; Wu, Hung C; Lin, Jarrn H; Lin, I K; Lee, Jyh F; Chen, Ching S

    2016-09-20

    In this work we developed a one-step process for synthesizing carboxylic-functionalized carbon nanofibers (CNFs)-encapsulated Ni magnetic nanoparticles (Ni@CNFs) that exhibit an excellent magnetic response and a large content of hydrophilic carboxylate groups with a negative charge (RCOO(-)) on the carbon surface. The carbon-encapsulated magnetic Ni nanoparticles could be rapidly separated from water, and they showed high efficiency for adsorption of the antibiotic sulfamethoxazole (SMX) in aqueous solution. The adsorption of SMX on Ni@CNFs as a function of pH was investigated, and the greatest adsorption occurred at pH 7.0. The adsorption isotherms for SMX on Ni@CNFs depended on different pH values. A Monte Carlo simulation was used to probe the relationship between molecular conformation and π-π interaction. The high adsorption of SMX on Ni@CNFs at pH 7.0 could be ascribed to deprotonated SMX being easily converted to a planar-like conformation, thereby resulting in the formation of π rings that were approximately parallel to the graphite surface and that enhanced strong π-π interaction. Electrostatic and π-π interactions both contributed to deprotonated SMX adsorption at pH 7.0, and they influenced the adsorption isotherm toward the Freundlich model. However, in weakly acidic environments (pH 2.0 and 4.0), the electrostatic interaction alone could induce an adsorption pattern that was similar to the Langmuir model. PMID:27578402

  11. Adsorption behavior of heavy metals on biomaterials.

    Science.gov (United States)

    Minamisawa, Mayumi; Minamisawa, Hiroaki; Yoshida, Shoichiro; Takai, Nobuharu

    2004-09-01

    We have investigated adsorption of Cd(II) and Pb(II) at pH 2-6.7 onto the biomaterials chitosan, coffee, green tea, tea, yuzu, aloe, and Japanese coarse tea, and onto the inorganic adsorbents, activated carbon and zeolite. High adsorptive capabilities were observed for all of the biomaterials at pH 4 and 6.7. In the adsorption of Cd(II), blend coffee, tea, green tea, and coarse tea have comparable loading capacities to activated carbon and zeolite. Although activated carbon, zeolite, and chitosan are utilized in a variety of fields such as wastewater treatment, chemical and metallurgical engineering, and analytical chemistry, these adsorbents are costly. On the other hand, processing of the test biomaterials was inexpensive, and all the biomaterials except for chitosan were able to adsorb large amounts of Pb(II) and Cd(II) ions after a convenient pretreatment of washing with water followed by drying. The high adsorption capability of the biomaterials prepared from plant materials is promising in the development of a novel, low-cost adsorbent. From these results, it is concluded that heavy metal removal using biomaterials would be an effective method for the economic treatment of wastewater. The proposed adsorption method was applied to the determination of amounts of Cd(II) and Pb(II) in water samples. PMID:15373400

  12. Adsorption of iodine on silver wire

    International Nuclear Information System (INIS)

    It is an important process in which iodine is adsorbed on silver wire during the preparation of 125I seed sources. In this paper, a technique of adsorption of iodine on silver wire was studied. The influence of several factors, such as the type of reagent for halogenation, the time for halogenation, the time for adsorption, pH value, ion concentration, carrier iodine and so on, on the utilization rate of 131I was investigated, and the effectiveness of our proposed technique for adsorption of iodine on silver wire was confirmed. The procedure is summarized as follows: silver wire acidification: using 4 mol/L HNO3 as halogenation agent, stirring acidified for 20 min; silver wire halogenation: used 2 mol/L NaClO3 as halogenated agent, halogenation for 3 h; adsorption of iodine on silver wire: room temperature, pH value for the reaction is about 3, the time for adsorption is 30 min, carrier iodine is 27.5 μg. Original radioactivity of reaction solution was determined based on radioactivity of source-core that user required. (authors)

  13. Adsorption of Cadmium By Silica Chitosan

    Directory of Open Access Journals (Sweden)

    Moftah Ali

    2013-03-01

    Full Text Available The adsorption process depends on initial concentration of Cd2+ and ratio of  chitosan in adsorbent. The present study deals with the competitive adsorption of Cd2+ ion onto silica graft with chitosan. Batch adsorption experiments were performed at five different initial Cd2+ concentrations (5, 10, 15, 20 and 25 ppm, on five different proportion from silica to chitosan (100%, 95%, 85%, 75% and 65% as adsorbent at pH 5. In the recovery process, the high recovery at 0.5 mg and observed the recovery decrease with increasing the initial concentration of Cd2+, and the low recovery at 0.25 mg from Cd2+. In this study, the adsorption capacity of Cd2+ in regard to the ratio of silica and chitosan hybrid adsorbents are examined in detail. The aim of this study to explore effects of initial concentrations of Cd2+, and the ratio of silica to chitosan on the adsorption and recovery of Cd2+.

  14. ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ON ATTAPULGITE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Batch adsorption experiments were carried out for the removal of methylene blue (MB) from aqueous solution using attapulgite as adsorbent. The effects of various parameters such as temperature, contact time, the pH value, and attapulgite dosage on the adsorption performance were investigated. The standard curve and regression equation were established by spectrophotometry. The adsorption experimental results showed that the adsorption equilibrium data were well in accord with Langmuir adsorptive model. The optimal result was acquired under the experimental condition of attapulgite dosage 0.18g, MB concentration 50.0mg/L, pH 10, and adsorption time 20min at room temperature.

  15. Dissociative adsorption of methane on surface oxide structures of Pd-Pt alloys

    CERN Document Server

    Dianat, Arezoo; Ciacchi, Lucio Colombi; Pompe, Wolfgang; Cuniberti, Gianaurelio; Bobeth, Manfred; 10.1021/jp905689t

    2010-01-01

    The dissociative adsorption of methane on variously oxidized Pd, Pt and Pd-Pt surfaces is investigated using density-functional theory, as a step towards understanding the combustion of methane on these materials. For Pd-Pt alloys, models of surface oxide structures are built on the basis of known oxides on Pd and Pt. The methane adsorption energy presents large variations depending on the oxide structure and composition. Adsorption is endothermic on the bare Pd(111) metal surface as well as on stable thin layer oxide structures such as the ($\\sqrt{5}\\times\\sqrt{5}$) surface oxide on Pd(100) and the PtO$_2$-like oxide on Pt(111). Instead, large adsorption energies are obtained for the (100) surface of bulk PdO, for metastable mixed Pd$_{1-x}$Pt$_x$O$_{4/3}$ oxide layers on Pt(100), and for Pd-Pt(111) surfaces covered with one oxygen monolayer. In the latter case, we find a net thermodynamic preference for a direct conversion of methane to methanol, which remains adsorbed on the oxidized metal substrates via w...

  16. A simple method to prepare magnetic modified beer yeast and its application for cationic dye adsorption.

    Science.gov (United States)

    Yu, Jun-Xia; Wang, Li-Yan; Chi, Ru-An; Zhang, Yue-Fei; Xu, Zhi-Gao; Guo, Jia

    2013-01-01

    The purpose of this research is to use a simple method to prepare magnetic modified biomass with good adsorption performances for cationic ions. The magnetic modified biomass was prepared by two steps: (1) preparation of pyromellitic dianhydride (PMDA) modified biomass in N, N-dimethylacetamide solution and (2) preparation of magnetic PMDA modified biomass by a situ co-precipitation method under the assistance of ultrasound irradiation in ammonia water. The adsorption potential of the as-prepared magnetic modified biomass was analyzed by using cationic dyes: methylene blue and basic magenta as model dyes. Optical micrograph and x-ray diffraction analyses showed that Fe(3)O(4) particles were precipitated on the modified biomass surface. The as-prepared biosorbent could be recycled easily by using an applied magnetic field. Titration analysis showed that the total concentration of the functional groups on the magnetic PMDA modified biomass was calculated to be 0.75 mmol g(-1) by using the first derivative method. The adsorption capacities (q(m)) of the magnetic PMDA modified biomass for methylene blue and basic magenta were 609.0 and 520.9 mg g(-1), respectively, according to the Langmuir equation. Kinetics experiment showed that adsorption could be completed within 150 min for both dyes. The desorption experiment showed that the magnetic sorbent could be used repeatedly after regeneration. The as-prepared magnetic modified sorbent had a potential in the dyeing industry wastewater treatment. PMID:22529003

  17. Abatement of VOCs with Alternate Adsorption and Plasma-Assisted Regeneration: A Review

    Directory of Open Access Journals (Sweden)

    Sharmin Sultana

    2015-04-01

    Full Text Available Energy consumption is an important concern for the removal of volatile organic compounds (VOCs from waste air with non-thermal plasma (NTP. Although the combination of NTP with heterogeneous catalysis has shown to reduce the formation of unwanted by-products and improve the energy efficiency of the process, further optimization of these hybrid systems is still necessary to evolve to a competitive air purification technology. A newly developed innovative technique, i.e., the cyclic operation of VOC adsorption and NTP-assisted regeneration has attracted growing interest of researchers due to the optimized energy consumption and cost-effectiveness. This paper reviews this new technique for the abatement of VOCs as well as for regeneration of adsorbents. In the first part, a comparison of the energy consumption between sequential and continuous treatment is given. Next, studies dealing with adsorption followed by NTP oxidation are reviewed. Particular attention is paid to the adsorption mechanisms and the regeneration of catalysts with in-plasma and post-plasma processes. Finally, the influence of critical process parameters on the adsorption and regeneration steps is summarized.

  18. Thermodynamic study of physical adsorption of oxygen on the cleavage face of lamellar crystals

    International Nuclear Information System (INIS)

    Adsorption isotherms of oxygen on the cleavage face of nine lamellar halides (NiCl2, CoBr2, CdCl2, CoI2, CdBr2, FeI2, MnI2, CaI2, PbI2) have been determined. Uniform adsorbents have been prepared by sublimation in a rapid current of inert gas. On these adsorbents, the adsorption isotherms show three steps corresponding to the formation of three successive ad-layers. At sufficiently low temperatures the ad-layers are formed during two-dimensional condensations, which are first order transitions. The analysis of the thermodynamic data derived from the adsorption isotherms, especially the entropy of the ad-layers and their critical temperature of two-dimensional condensation, suggest that the first oxygen layer is solid while the next ones are liquid. As for rare gases we observe that surface relief has an outstanding effect on the structure of the first layer. Adsorption isotherms of oxygen and argon on exfoliated graphite have also been determined. Beyond the first, the ad-layers of oxygen are liquid while these of argon are solid. (author)

  19. Adsorption of quantum dots onto polymer and Gemini surfactant films: a quartz crystal microbalance study.

    Science.gov (United States)

    Alejo, T; Merchán, M D; Velázquez, M M

    2014-08-26

    We used quartz crystal microbalance with dissipation to study the mechanical properties, the kinetics of adsorption, and the amount of CdSe quantum dots (QDs) adsorbed onto a SiO2 sensor, referred as bare sensor, onto the sensor modified with a film of the polymer poly(maleic anhydride-alt-1-octadecene), PMAO, or with a film of the Gemini surfactant ethyl-bis(dimethyl octadecyl ammonium bromide), abbreviated as 18-2-18. Results showed that when the sensor is coated with polymer or surfactant molecules, the coverage increases compared with that obtained for the bare sensor. On the other hand, rheological properties and kinetics of adsorption of QDs are driven by QD nanoparticles. Thus, the QD films present elastic behavior, and the elasticity values are independent of the molecule used as coating and similar to the elasticity value obtained for QDs films on the bare sensor. The QD adsorption is a two-step mechanism in which the fastest process is attributed to the QD adsorption onto the solid substrate and the slowest one is ascribed to rearrangement movements of the nanoparticles adsorbed at the surface. PMID:25093530

  20. Uranium and thorium adsorption from aqueous solution using a novel polyhydroxyethylmethacrylate-pumice composite.

    Science.gov (United States)

    Akkaya, Recep

    2013-06-01

    Poly(hydroxyethylmethacrylate-pumice), [P(HEMA-Pum)], composite was synthesized by free radical polymerization in aqueous solution. The adsorptive features of P(HEMA-Pum) composite were investigated for UO2(2+) and Th(4+) using a range of pH, concentration, time (kinetics), temperature (thermodynamics), ionic strength and selectivity, and the related parameters were derived from the obtained results. These results indicated that all adsorbents had high affinity to the uranium and thorium ions. The parameters obtained from Langmuir, Freundlich and Dubinin-Radsushkevich models fit the data well. The values of enthalpy and entropy changes showed that the overall adsorption process was endothermic (ΔH > 0) and increasing entropy (ΔS > 0), and it was spontaneous (ΔG < 0) as expected. The adsorption kinetics following the pseudo-second order model indicated that the rate-controlling step was chemical adsorption that occurred by ion exchange process. Reusability of P(HEMA-Pum) was also investigated, and it was found that the composite could be used at least 5 times.

  1. Tungsten oxide--fly ash oxide composites in adsorption and photocatalysis.

    Science.gov (United States)

    Visa, Maria; Bogatu, Cristina; Duta, Anca

    2015-05-30

    A novel composite based on tungsten oxide and fly ash was hydrothermally synthetized to be used as substrate in the advanced treatment of wastewaters with complex load resulted from the textile industry. The proposed treatment consists of one single step process combining photocatalysis and adsorption. The composite's crystalline structure was investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to analyze the morphology. The adsorption capacity and photocatalytic properties of the material were tested on mono- and multi-pollutants systems containing two dyes (Bemacid Blau - BB and Bemacid Rot - BR) and one heavy metal ion-Cu(2+), and the optimized process conditions were identified. The results indicate better removal efficiencies using the novel composite material in the combined adsorption and photocatalysis, as compared to the separated processes. Dyes removal was significantly enhanced in the photocatalytic process by adding hydrogen peroxide and the mechanism was presented and discussed. The pseudo second order kinetics model best fitted the experimental data, both in the adsorption and in the combined processes. The kinetic parameters were calculated and correlated with the properties of the composite substrate.

  2. Visual Basic in easy steps

    CERN Document Server

    McGrath, Mike

    2011-01-01

    Visual Basic in Easy Steps begins by describing the installation process, then introduces form controls, application properties, the programming language, and problem-solving techniques. It illustrates how to build and deploy a complete Windows application and how to create macros for Microsoft Office and web pages for Internet Explorer. By the end of this book, readers will have gained a sound understanding of Visual Basic - even without previous knowledge of programming languate - and be able to create their own interactive applications.

  3. First Steps for New Government

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The formation of a unity government brings hopes of peace and stability to war-torn Iraq, though violence continues Thirty-eight months after the war on Iraq began, and after five months of wrangling over cabinet posts, a new national government led by Nuri al-Maliki was sworn in, marking a great step in the country's post-war reconstruction but one on a road that appears to be growing ever longer and rockier.

  4. Stepped frequency ground penetrating radar

    Science.gov (United States)

    Vadnais, Kenneth G.; Bashforth, Michael B.; Lewallen, Tricia S.; Nammath, Sharyn R.

    1994-01-01

    A stepped frequency ground penetrating radar system is described comprising an RF signal generating section capable of producing stepped frequency signals in spaced and equal increments of time and frequency over a preselected bandwidth which serves as a common RF signal source for both a transmit portion and a receive portion of the system. In the transmit portion of the system the signal is processed into in-phase and quadrature signals which are then amplified and then transmitted toward a target. The reflected signals from the target are then received by a receive antenna and mixed with a reference signal from the common RF signal source in a mixer whose output is then fed through a low pass filter. The DC output, after amplification and demodulation, is digitized and converted into a frequency domain signal by a Fast Fourier Transform. A plot of the frequency domain signals from all of the stepped frequencies broadcast toward and received from the target yields information concerning the range (distance) and cross section (size) of the target.

  5. Adsorption on Highly Ordered Porous Alumina

    Science.gov (United States)

    Mistura, Giampaolo; Bruschi, Lorenzo; Lee, Woo

    2016-10-01

    Porous anodic aluminum oxide (AAO) is characterized by a regular arrangement of the pores with a narrow pore size distribution over extended areas, uniform pore depth, and solid pore walls without micropores. Thanks to significant improvements in anodization techniques, structural engineering of AAO allows to accurately tailor the pore morphology. These features make porous AAO an excellent substrate to study adsorption phenomena. In this paper, we review recent experiments involving the adsorption in porous AAO. Particular attention will be devoted to adsorption in straight and structured pores with a closed end which shed new light on fundamental issues like the origin of hysteresis in closed end pores and the nature of evaporation from ink-bottle pores. The results will be compared to those obtained in other synthetic materials like porous silicon and silica.

  6. GENERAL: Cluster Growth Through Monomer Adsorption Processes

    Science.gov (United States)

    Ke, Jian-Hong; Lin, Zhen-Quan; Chen, Xiao-Shuang

    2010-02-01

    We propose a monomer adsorption model, in which only the monomers are allowed to diffuse and adsorb onto other clusters. By means of the generalized rate equation we investigate the kinetic behavior of the system with a special rate kernel. For the system without monomer input, the concentration aj(t) of the Aj clusters (j > 1) asymptotically retains a nonzero quantity, while for the system with monomer input, it decays with time and vanishes finally. We also investigate the kinetics of an interesting model with fixed-rate monomer adsorption. For the case without monomer source, the evolution of the system will halt at a finite time; while the system evolves infinitely in time in the case with monomer source. Finally, we also suggest a connection between the fixed-rate monomer adsorption systems and growing networks.

  7. Adsorption on smooth electrodes: A radiotracer study

    International Nuclear Information System (INIS)

    Adsorption on solids is a complicated process and in most cases, occurs as the early stage of other more complicated processes, i.e. chemical reactions, electrooxidation, electroreduction. The research reported here combines the electroanalytical method, cyclic voltammetry, and the use of radio-labeled isotopes, soft beta emitters, to study adsorption processes at smooth electrodes. The in-situ radiotracer method is highly anion (molecule) specific and provides information on the structure and composition of the electric double layer. The emphasis of this research was on studying adsorption processes at smooth electrodes of copper, gold, and platinum. The application of the radiotracer method to these smooth surfaces have led to direct in-situ measurements from which surface coverage was determined; anions and molecules were identified; and weak interactions of adsorbates with the surface of the electrodes were readily monitored. 179 refs

  8. Adsorption of aluminium by stream particulates.

    Science.gov (United States)

    Tipping, E; Ohnstad, M; Woof, C

    1989-01-01

    An experimental study was made of the adsorption of aluminium by fine particulates from Whitray Beck, a hill stream in NW England. Adsorption increased with Al(3) activity, pH and concentration of particles, and could be quantitatively described by the empirical equation: [Formula: see text] [particles] where square brackets indicate concentrations, curly brackets, activities, and alpha, beta and gamma are constants with values of 5.14x10(-10) (mol litre(-1))(2.015) (g particles litre(-1))(-1), 0.457, and 1.472, respectively. For the experimental data, the equation gave a correlation ratio of 0.99. The equation accounts reasonably well for the adsorption of Al by particulates from seven other streams. In applying the equation, it must be borne in mind that the desorption kinetics of Al depend on pH, and rapid reversibility (or=10%) of total monomeric Al. PMID:15092454

  9. Novel nano bearings constructed by physical adsorption

    Science.gov (United States)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  10. Hydrophobic nano-carrier for lysozyme adsorption

    Indian Academy of Sciences (India)

    CANAN ALTUNBAS; FULDEN ZEYNEP URAL; MURAT UYGUN; NESIBE AVCIBASI; UGUR AVCIBASI; DENIZ AKTAS UYGUN; SINAN AKGÖL

    2016-04-01

    In this work, poly(HEMA–APH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique.Magnetic behaviour was introduced by simple addition of Fe$_3$O$_4$ into the polymerization medium.Characterization of the nanoparticle was carried out by FTIR, ESR, SEM, AFM and EDX analyses. These synthesized magnetic nanoparticles were used for adsorption of lysozyme. For this purpose, adsorption conditions wereoptimized and maximum lysozyme binding capacity was found to be 278.8 mg g$^{−1}$ polymer in pH 7.0 phosphate buffer at 25$^{\\circ}$C. Desorption and reusability properties of the nanoparticles were investigated and lysozyme adsorption efficiency did not change significantly at the end of the 10 successive reuses.

  11. Adsorption on Highly Ordered Porous Alumina

    Science.gov (United States)

    Mistura, Giampaolo; Bruschi, Lorenzo; Lee, Woo

    2016-04-01

    Porous anodic aluminum oxide (AAO) is characterized by a regular arrangement of the pores with a narrow pore size distribution over extended areas, uniform pore depth, and solid pore walls without micropores. Thanks to significant improvements in anodization techniques, structural engineering of AAO allows to accurately tailor the pore morphology. These features make porous AAO an excellent substrate to study adsorption phenomena. In this paper, we review recent experiments involving the adsorption in porous AAO. Particular attention will be devoted to adsorption in straight and structured pores with a closed end which shed new light on fundamental issues like the origin of hysteresis in closed end pores and the nature of evaporation from ink-bottle pores. The results will be compared to those obtained in other synthetic materials like porous silicon and silica.

  12. Heavy metal adsorption by sulphide mineral surfaces

    Science.gov (United States)

    Jean, Gilles E.; Bancroft, G. Michael

    1986-07-01

    The adsorption of aqueous Hg 2+, Pb 2+, Zn 2+ and Cd 2+ complexes on a variety of sulphide minerals has been studied as a function of the solution pH and also as a function of the nature of the ligands in solution. Sulphide minerals are excellent scavengers for these heavy metals. The adsorption is strongly pH dependent, i.e. there is a critical pH at which the adsorption increases dramatically. The pH dependence is related to the hydrolysis of the metal ions. Indirect evidence suggests that the hydrolyzed species are adsorbed directly on the sulphide groups, probably as a monolayer. The results also suggest the presence of MCI n2- n species physisorbed on the adsorbed monolayer. A positive identification of the adsorbed species was not possible using ESCA/XPS.

  13. One step synthesis of polyacrylamide functionalized graphene and its application in Pb(II) removal

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhiwei; Zhang, Yaoyao; Qian, Xiaoming; Shi, Jie; Chen, Lei; Li, Baodong; Niu, Jiarong; Liu, Liangsen, E-mail: 83019163@163.com

    2014-10-15

    Highlights: • PAM-g-graphene is synthesized by the co-irradiation between GO and AM monomers. • PAM graft on GO has led to the exfoliation of GO into individual sheets. • The γ-ray induced reduction of GO. • PAM-g-graphene exhibits high adsorption capacities toward Pb(II) ions. • PAM-g-graphene provides a new idea for heavy metal pollutants’ removal in water. - Abstract: Polyacrylamide grafted graphene (PAM-g-graphene) from graphite oxide (GO) was successfully prepared by γ-ray irradiation with acrylamide monomers in aqueous at room temperature in this paper. Our strategy involves the PAM chains graft on the surface and between the layers of GO by in situ radical polymerization which led to the exfoliation of GO into individual sheets. Results show that the degree of grafting of PAM-g-graphene samples is 24.2%, and the thickness is measured to be 2.59 nm. Moreover, the as-prepared PAM-g-graphene with some amino from PAM and little oxygen functional groups exhibit superior adsorption of Pb(II) ions. The adsorption processes reach equilibrium in just 30 min and the adsorption isotherms are described well by Langmuir and Freundlich classical isotherms models. The determined adsorption capacity of PAM-g-graphene is 819.67 mg g{sup −1} (pH 6) for Pb(II), which is 20 times and 8 times capacities of that for graphene nanosheets and carbon nanotubes according to reports, respectively. This chemically modified graphene synthesized by this fast one-step approach, featuring a good versatility and adaptability, excellent adsorption capacity and rapid extraction, may provide a new idea for the global problem of heavy metal pollutants’ removal in water.

  14. Efficient adsorption refrigerators integrated with heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.Z. [Institute of Refrigeration and Cryogenics, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2008-03-15

    Several novel ideas to use heat pipes in adsorption water chiller or ice maker are presented in this paper. Experimental results have shown that the adsorption refrigerators are very efficient. The first example of such systems is a small scale silica gel-water adsorption water chiller with cooling power rated as 10 kW; the system could be powered by 60-100 C hot water, a cooling COP = 0.4 has been achieved when driven by 85 C hot water. This adsorption chiller has been used for solar powered air conditioner and also as the chiller for CCHP system. The second example is a silica gel-water adsorption room air conditioner powered by 80 C hot water. The system is very compact and is suggested for potential applications of micro CCHP system based on fuel cells. The system has a COP of over 0.3 and cooling power of about 1 kW. The third example is the use of split heat pipes to heat or cool the adsorber for making ice in fishing boats. The application of these technologies avoids the corrosion of adsorber at the heating phase by exhausted gases and at the cooling phase by seawater, and also has the advantage of high heat transfer performance. With such arrangement and careful considerations of the arrangement of wicks in heat pipes, and also the use of composite adsorbent (calcium chloride and activated carbon)-ammonia adsorption pair, the system test has shown the specific refrigeration power for more than 730 W/kg at -15 C. (author)

  15. Step-By-Step: Life Cycle Radioactive Waste Management

    International Nuclear Information System (INIS)

    Radioactive waste is an unavoidable by-product when nuclear technologies are used for electricity production and for beneficial practices in medicine, agriculture, research and industry. When the radioactivity of the waste is above a certain threshold, the waste requires special disposal methods. Through extensive research, standards and approaches have been developed for safely and securely preparing for and managing radioactive waste disposal. In the course of its journey from the point of generation to disposal, radioactive waste undergoes a number of predisposal management treatment steps to transform it into a safe, stable and manageable form suitable for transport, storage and disposal

  16. Multilayer adsorption mechanism of coal surface adsorption to three oxygen molecule

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-feng; LI Zhi-gang; WANG Xin-yang; SUN Yan-qiu

    2008-01-01

    Compared chemical bonds change situation of coal surface and oxygen mole-cules before and after coal surface adsorption to three oxygen molecules,after adsorption each oxygen molecule's chemical bond got longer,but had not broken,the coal surface's chemical bonds changed a little.It proves that the coal surface adsorption to five oxygen molecules is the physical adsorption and is the multilayer adsorption according to the optimized geometry structure.The oxygen molecule's bond length that adsorbed by the side chain of coal surface changes most from 1.258 2×10 10 m to 1.316 8×10 10 m,which indicates this oxygen molecular to be the liveliest.The analysis of charge population reveals that how many electrons shift in the atom is directly proportional to the change of chemical bonds.The more electrons shift in the atom,the more molecule chemical bond changes.In the adsorption state,which is composed of coal surface and five oxygen molecules,the vibration frequency of oxygen molecules drops off,and the adsorption energy reached by calculation is 202.11 kJ/mol.

  17. Multilayer adsorption mechanism of coal surface adsorption to three oxygen molecule

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-feng; LI Zhi-gang; WANG Xin-yang; SUN Yan-qiu

    2008-01-01

    Compared chemical bonds change situation of coal surface and oxygen mole-cules before and after coal surface adsorption to three oxygen molecules, after adsorption each oxygen molecule's chemical bond got longer, but had not broken, the coal surface's chemical bonds changed a little. It proves that the coal surface adsorption to five oxygen molecules is the physical adsorption and is the multilayer adsorption according to the op-timized geometry structure. The oxygen molecule's bond length that adsorbed by the side chain of coal surface changes most from 1.258 2×10-10 m to 1.316 8×10-10 m, which indi-cates this oxygen molecular to be the liveliest. The analysis of charge population reveals that how many electrons shift in the atom is directly proportional to the change of chemical bonds. The more electrons shift in the atom, the more molecule chemical bond changes. In the adsorption state, which is composed of coal surface and five oxygen molecules, the vibration frequency of oxygen molecules drops off, and the adsorption energy reached by calculation is 202.11 kJ/mol.

  18. Optimization and Control of Pressure Swing Adsorption Processes Under Uncertainty

    KAUST Repository

    Khajuria, Harish

    2012-03-21

    The real-time periodic performance of a pressure swing adsorption (PSA) system strongly depends on the choice of key decision variables and operational considerations such as processing steps and column pressure temporal profiles, making its design and operation a challenging task. This work presents a detailed optimization-based approach for simultaneously incorporating PSA design, operational, and control aspects under the effect of time variant and invariant disturbances. It is applied to a two-bed, six-step PSA system represented by a rigorous mathematical model, where the key optimization objective is to maximize the expected H2 recovery while achieving a closed loop product H2 purity of 99.99%, for separating 70% H2, 30% CH4 feed. The benefits over sequential design and control approach are shown in terms of closed-loop recovery improvement of more than 3%, while the incorporation of explicit/multiparametric model predictive controllers improves the closed loop performance. © 2012 American Institute of Chemical Engineers (AIChE).

  19. Simultaneous metal adsorption on tannin resins

    International Nuclear Information System (INIS)

    Vegetable tannin sorbent is evaluated as ion exchange resin using a multitracer study on the adsorption behavior of various elements. Lisiloma latisiliqua L. tannins, polycondensated into spherical pellets were chosen as sorbent resin material. Sorption evaluation of Ce, Cu(II), U(VI), Eu, Fe(III), Th, Nd as representatives of different classes of metal ions were done at different pH values. The distribution ratio of the studied elements was calculated from laboratory experiments. Tannic ion exchange material shows excellent ability for actinides and rare earth elements adsorption from waters. Using radiotracers, the number of catechins subunits involve in each tannin-metal complex was determined. (author)

  20. Adsorption on mixtures of ion exchangers

    International Nuclear Information System (INIS)

    A theoretical study has been made of adsorption on mixtures of ion exchangers. The effect of variables such as the concentration of the ion being adsorbed, the concentration of the supporting electrolyte, loading, the values of the capacities and equilibrium constants for the various exchange processes, and the fraction of each adsorber in the mixture on the observed distribution coefficient has been investigated. A computer program has been written to facilitate the calculation of distribution coefficients for the adsorption of an ion on a given mixture of ion exchangers under a specified set of conditions

  1. Adsorption Behavior of Plutonium on Clay

    Institute of Scientific and Technical Information of China (English)

    LONG; Hao-qi; BAO; Liang-jin; SONG; Zhi-xin; WANG; Bo

    2013-01-01

    In this study,the adsorption distribution ratios of Pu in the Longdong clays were measured with batch method under hypoxic conditions,and the influence of the liquid-solid ratio and pH on the adsorption distribution ratio also was discussed.The initial concentration of Pu is about 1×10-10 mol/L,and the solution pH value was adjusted with NaOH or HClO4.The temperature of experiments was(30±

  2. Adsorption of amylase enzyme on ultrafiltration membranes

    DEFF Research Database (Denmark)

    Beier, Søren; Enevoldsen, Ann Dorrit; Kontogeorgis, Georgios;

    2007-01-01

    A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of an amylase-F has been measured on two different ultrafiltration membranes, both with a cut-off value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface-mo...... is independent of the membrane type. At higher concentrations of enzyme, concentration polarization effects can not be neglected. Therefore stagnant film theory and the osmotic pressure model can describe the dependency between flux and bulk concentration....

  3. Investigation on Adsorption of Lithospermum erythrorhizon onto Fungal Cell Wall Polysaccharides

    Institute of Scientific and Technical Information of China (English)

    孟琴; 薛莲

    2003-01-01

    A culture of Lithosperrnum erythrorhizon adsorbed on fungal cell wall polysaccharides, a novel bioadsorbent made from fungal cell wall, has been established in this paper. Three steps were involved in this immobilization. The first step was preparation of suspended plant cells from tightly aggregated plant cell clumps. The disassembled ratio of 0.715g·g-1 (the disassembled cells over total cells) was obtained under optimum condition for the enzymatic reaction. Then, the adsorption of plant cells onto fungal cell wall polysaccharides was conducted and the saturated capacity of 12g cell per gram of carrier was obtained in adsorption immobilization. Finally, the culture of cells adsorbed on fungal cell wall polysaccharides was compared with that of cells entrapped in alginate or suspension cell culture. While exposed to in situ liquid paraffin extraction coupled with cell culture, the shikonin productivity of immobilized cells by adsorption was 10.67g·L-1, which was 1.8 times of that in suspension culture and 1.5 times of that entrapped in alginate.

  4. Application of the sanderson polar covalence model to energetics of CO adsorption

    Science.gov (United States)

    Frese, Karl W.

    1988-08-01

    The model of polar covalence developed by R.T. Sanderson was used to calculate energies of chemisorption of CO g on metal surfaces. Internal energies of adsorption were calculated for four stereochemical possibilities including linear, two site bridge bonded, and dissociated CO on fourteen first, second, and third row transition metals. The influence of surface steps, other defects, and CO-CO interactions were not calculated, although the influence of steps on certain metals is discussed. The effect of metal site coordination number was also calculated. Higher coordination numbers, are generally associated with longer bond lengths and smaller heats of adsorption. Very good agreement, less than 3 kcal mol -1 difference between experiment and calculation, was observed for molecularly adsorbed CO. The enthalpy and Gibbs energy of dissociative adsorption at 298 K were calculated for seventeen transition metals and Si. CO dissociation is thermodynamically allowed on Mn, Cr, Fe, Ni, Re, W and Si at both 10 -10 Torr and 1 atm CO. Dissociation is forbidden on Ru, Rh, Ir, Ag, Pd, Au, and Pt at both pressures. Dissociation is forbidden at 10 -10 Torr, but allowed at 1 atm CO on Co, Cu, Mo, and Os.

  5. Acta Clinica Croatica: progress of a journal step by step.

    Science.gov (United States)

    Ramljak, Gordana

    2014-03-01

    The journal Acta Clinica Croatica (ACC) was founded in 1962 under the title Anali Bolnice Dr. M. Stojanović. In 1995, the title of the journal was changed into its present form and ever since all papers have been published in English. In 2000, the electronic (online) edition of the ACC was released in addition to the print version. The paper presents development of the journal from 1962 to 2012 based on the analysis of the following SCOPUS citation index parameters: type and number of documents published in the journal; number of citations; and number of domestic and foreign authors. The studied period was analyzed in three time segments: the period from 1995 to 1999, the period from 2000 to 2006 and the period from 2007 to 2012. The same parameters were analyzed in the Web of Science/SCI-Expanded bibliographic and citation index for the 2007-2012 period. The increasing number of documents, authors (both domestic and foreign) and citations demonstrates gradual rise in the quality, visibility and impact of the journal. The fifty years of experience show that a goal, at first very distant and almost unachievable, may be reached by progressing step by step.

  6. Assessing the adsorption properties of shales

    Science.gov (United States)

    Pini, Ronny

    2015-04-01

    Physical adsorption refers to the trapping of fluid molecules at near liquid-like densities in the pores of a given adsorbent material. Fine-grained rocks, such as shales, contain a significant amount of nanopores that can significantly contribute to their storage capacity. As a matter of fact, the current ability to extract natural gas that is adsorbed in the rock's matrix is limited, and current technology focuses primarily on the free gas in the fractures (either natural or stimulated), thus leading to recovery efficiencies that are very low. Shales constitute also a great portion of so-called cap-rocks above potential CO2 sequestration sites; hereby, the adsorption process may limit the CO2 mobility within the cap-rock, thus minimizing the impact of leakage on the whole operation. Whether it is an unconventional reservoir or a cap-rock, understanding and quantifying the mechanisms of adsorption in these natural materials is key to improve the engineering design of subsurface operations. Results will be presented from a laboratory study that combines conventional techniques for the measurement of adsorption isotherms with novel methods that allows for the imaging of adsorption using x-rays. Various nanoporous materials are considered, thus including rocks, such as shales and coals, pure clay minerals (a major component in mudrocks) and engineered adsorbents with well-defined nanopore structures, such as zeolites. Supercritical CO2 adsorption isotherms have been measured with a Rubotherm Magnetic Suspension balance by covering the pressure range 0.1-20~MPa. A medical x-ray CT scanner has been used to identify three-dimensional patterns of the adsorption properties of a packed-bed of adsorbent, thus enabling to assess the spatial variability of the adsorption isotherm in heterogeneous materials. The data are analyzed by using thermodynamically rigorous measures of adsorption, such as the net- and excess adsorbed amounts and a recently developed methodology is

  7. Removal of Pyrethrin from Aqueous Effluents by Adsorptive Micellar Flocculation

    Directory of Open Access Journals (Sweden)

    Pardon K. Kuipa

    2015-01-01

    Full Text Available The equilibrium adsorption of pyrethrin onto aggregates formed by the flocculation of micelles of the surfactant sodium dodecyl sulphate (SDS with aluminium sulphate is reported. The experimental results were analysed using different adsorption isotherms (Langmuir, Freundlich, Redlich-Peterson, Sips, Radke-Prausnitz, Temkin, linear equilibrium, and the Dubin-Radushkevich isotherms. The Freundlich and linear equilibrium isotherms best describe the adsorption of pyrethrin onto SDS micellar flocs, with the Freundlich adsorption constant, KF, and the mass distribution coefficient, KD, of 64.266 ((mg/g(L/mg1/n and 119.65 L/g, respectively. Applicability of the Freundlich adsorption model suggests that heterogeneous surface adsorption affects the adsorption. The mean free energy value estimated using the Dubinin-Radushkevich isotherm was 0.136 kJ/mol indicating that physisorption may be predominant in the adsorption process.

  8. Adsorption of thorium from aqueous solutions by perlite.

    Science.gov (United States)

    Talip, Z; Eral, M; Hiçsönmez, U

    2009-02-01

    The use of expanded perlite for the adsorption of thorium from aqueous solution by batch technique is presented. The effects of particle size, pH of the solution, initial thorium concentration, shaking time, V/m ratio and temperature were determined. It was found that the adsorption capacity increases by the increase in the pH of the suspensions. The rate of thorium adsorption on expanded perlite was observed to be fast in the first hour of the reaction time. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models and the adsorption experiments conducted at 30 +/- 1 degrees C showed that the adsorption isotherms correlated well with the Langmuir model. From the adsorption data, thermodynamic parameters such as DeltaG(o), DeltaH(o) and DeltaS(o) were calculated as a function of temperature.

  9. Unexpected coupling between flow and adsorption in porous media.

    Science.gov (United States)

    Vanson, Jean-Mathieu; Coudert, François-Xavier; Rotenberg, Benjamin; Levesque, Maximilien; Tardivat, Caroline; Klotz, Michaela; Boutin, Anne

    2015-08-14

    We study the interplay between transport and adsorption in porous systems under a fluid flow, based on a lattice Boltzmann scheme extended to account for adsorption. We performed simulations on well-controlled geometries with slit and grooved pores, investigating the influence of adsorption and flow on dispersion coefficient and adsorbed density. In particular, we present a counterintuitive effect where fluid flow induces heterogeneity in the adsorbate, displacing the adsorption equilibrium towards downstream adsorption sites in grooves. We also present an improvement of the adsorption-extended lattice Boltzmann scheme by introducing the possibility for saturating Langmuir-like adsorption, while earlier work focused on linear adsorption phenomena. We then highlight the impact of this change in situations of high concentration of adsorbate. PMID:26139013

  10. The Calculation of Adsorption Isotherms from Chromatographic Peak Shapes

    Science.gov (United States)

    Neumann, M. G.

    1976-01-01

    Discusses the relationship between adsorption isotherms and elution peak shapes in gas chromatography, and describes a laboratory experiment which involves the adsorption of hexane, cyclohexane, and benzene on alumina at different temperatures. (MLH)

  11. Adsorption effect on the dynamic response of a biochemical reaction in a biofilm reactor for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tsuneda, S.; Inoue, Y.; Auresenia, J.; Hirata, A. [Department of Chemical Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

    2003-09-01

    The dynamic behavior of a completely mixed, three-phase, fluidized bed biofilm reactor treating simulated domestic wastewater was studied with step changes in inlet concentration. It was found that the response curves showed second order characteristics, i.e., as the inlet concentration was increased, the outlet concentration also increased, reached a peak value and then decreased until it leveled to a new steady-state value corresponding to the new inlet concentration level. Nonlinear regression analysis was performed using Monod-type rate equations with and without an adsorption term. As a result, the theoretical curve of the kinetic model that incorporates the adsorption term has best fit to the actual response in most cases. Thus, it was concluded that the adsorption of a substrate onto the biofilm and carrier particles has a significant effect on the dynamic response in biofilm processes. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  12. Insights on finite size effects in Ab-initio study of CO adsorption and dissociation on Fe 110 surface

    CERN Document Server

    Chakrabarty, Aurab; Mousseau, Normand; Becquart, Charlotte S; Mellouhi, Fadwa El

    2016-01-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps to carburization of metal. Here, we use density functional theory total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. For the absorption of CO, the contribution from van der Waals interaction in the computation of adsorption parameters is found important in small systems with high CO-coverages. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in larger surface systems associated with dilute CO-coverages, the dissociation barrier is significantly decreased. The elastic deformation of the surface is generic and can potentially applicable for all similar metal-hydrocarbon reactions and therefore a dilute coverage is necessary for the simul...

  13. Characterization and ciprofloxacin adsorption properties of activated carbons prepared from biomass wastes by H3PO4 activation.

    Science.gov (United States)

    Sun, Yuanyuan; Li, Hong; Li, Guangci; Gao, Baoyu; Yue, Qinyan; Li, Xuebing

    2016-10-01

    As biomass wastes, Arundo donax Linn and pomelo peel were used as precursors for activated carbons (ALAC and PPAC) preparation by phosphoric acid activation. The pore structure and surface acidic functional groups of both carbons were characterized by nitrogen adsorption/desorption experiment, NH3-temperature-programmed desorption (NH3-TPD) and Fourier transform infrared spectroscopy (FTIR). A batch of experiments was carried out to investigate the adsorption performances of ciprofloxacin under different conditions. Results showed that PPAC exhibited larger surface area (1252m(2)/g) and larger portion of mesoporous, while ALAC was typical of microporous materials. Results from NH3-TPD suggested that ALAC was characteristic of more acidic functional group than PPAC. The maximum monolayer adsorption capability was 244mg/g for ALAC and 400mg/L for PPAC. Kinetics studies showed intra-particle diffusion was not the unique rate-controlling step. Boundary layer resistance existed between adsorbent and adsorbate. PMID:27034157

  14. Research on the chemical adsorption precursor state of CaCl2-NH3 for adsorption refrigeration

    Institute of Scientific and Technical Information of China (English)

    WANG Liwei; WANG Ruzhu; WU Jingyi; WANG Kai

    2005-01-01

    As a type of chemical adsorption working pair, the physical adsorption occurs first for CaCl2-NH3 because the effective reaction distance for van der Waals force is longer than that for chemical reaction force, and this physical adsorption state is named the precursor state of chemical adsorption. In order to get the different precursor states of CaCl2-NH3, the different distances between NH3 gas and Ca2+ are realized by the control of different phenomena of swelling and agglomeration in the process of adsorption. When the serious swelling exists while the agglomeration does not exist in the process of adsorption, experimental results show that the activated energy consumed by adsorption reaction increases for the reason of longer distance between Ca2+ and NH3, and at the same time the performance attenuation occurs in the repeated adsorption cycles. When the agglomeration occurs in the process of adsorption, the activated energy for the transition from precursor state to chemical adsorption decreases because the distance between NH3 gas and Ca2+ is shortened by the limited expansion space of adsorbent, and at the same time the performance attenuation does not occur. The adsorption refrigeration isobars are researched by the precursor state of chemical adsorption; results also show that the precursor state is a key factor for isobaric adsorption performance while the distribution of Ca2+ does not influence the permeation of NH3 gas in adsorbent.

  15. Steps Towards an Evolutionary Physics

    CERN Document Server

    Tiezzi, E

    2006-01-01

    If thermodynamics is to physics as logic is to philosophy, recent theoretical advancements lend new coherence to the marvel and dynamism of life on Earth. Enzo Tiezzi's "Steps Towards an Evolutionary Physics" is a primer and guide, to those who would to stand on the shoulders of giants to attain this view: Heisenberg, Planck, Bateson, Varela, and Prigogine as well as notable contemporary scientists. The adventure of such a free and enquiring spirit thrives not so much on answers as on new questions. The book offers a new gestalt on the uncertainty principle and concept of probability. A wide r

  16. Adsorption of copper ions from aqueous solutions on natural zeolite

    OpenAIRE

    Zendelska, Afrodita; Golomeova, Mirjana; Blažev, Krsto; Krstev, Boris; Golomeov, Blagoj; Krstev, Aleksandar

    2015-01-01

    The adsorption of copper ions from synthetic aqueous solutions on natural zeolite (clinoptilolite) was examined. In order to determine the rate of adsorption and the copper uptake at equilibrium, a series of experiments were performed under batch conditions from single ion solutions. Equilibrium data were evaluated based on adsorption (Langmuir and Freundlich) isotherms. The adsorption kinetics is reasonably fast. In the first 20 min of the experiment, approximately 80% of Cu2+ io...

  17. Adsorption of D113 Resin for Dysprosium(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The adsorption behavior and mechanism of D113 resin for Dy(Ⅲ) was investigated by using the method of resin adsorption. Experimental results show that the optimum medium pH of adsorption of D113 resin for Dy3+ is pH=6.00 in the HAc-NaAc medium. The static adsorption capacity of D113 resin for Dy3+chemical analysis and IR spectra.

  18. ADSORPTION OF PHENOL AND NITROPHENOLS ON A HYPERCROSSLINKED POLYMERIC ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent wasstudied as a function of the solution concentration and temperature. Adsorption isotherms of phenoland nitrophenols on hypercrosslinked resin were determined. These isotherms were modeledaccording to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols onhypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for allphenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of thefirst-order kinetics. The rate constants at 303K were calculated.

  19. Adsorption of microcystins and anatoxin-a on nanofiltration membranes

    OpenAIRE

    Ribau Teixeira, Margarida; Rosa, Maria João

    2011-01-01

    This work pretends to study the adsorption of microcystin-LR (MC-LR) and anatoxin-a (ATX-a) on nanofiltration membranes and to understand the adsorption behaviour with the solution chemistry (background natural organic matter (NOM) and in the presence of ATX-a). Results demonstrate that MC-LR adsorption increases with water recovery due to the increase in MC-LR feed concentration. MC-LR adsorption is governed by hydrophobic interactions established between the membrane surface and...

  20. Theoretical study of adsorption of lithium atom on carbon nanotube

    OpenAIRE

    Senami, Masato; Ikeda, Yuji; Fukushima, Akinori; Tachibana, Akitomo

    2011-01-01

    We investigate the adsorption of lithium atoms on the surface of the (12,0) single wall carbon nanotube (SWCNT) by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsive...

  1. Adsorption of Crystal Violet Dye onto Tamarind Seed Powder

    OpenAIRE

    Himanshu Patel; R. T. Vashi

    2010-01-01

    The present investigation describes adsorption of crystal violet dye from its aqueous solution onto tamarind (Tamarindus indica) fruit shell powder. Initial concentration, agitation speed and pH with various temperature have been studied, in which pH was found to be most effective. The adsorption data were mathematically analyzed using adsorption isotherm like Freundlich and Langmuir isotherm to study adsorption mechanism of crystal violet onto this seed powder. Freundlich isotherm was found ...

  2. RADICAL FLOW IN POROUS MEDIA WITH DISPERSION AND ADSORPTION

    Institute of Scientific and Technical Information of China (English)

    LIU Ci-qun; GUO Bai-qi; SONG Fu-quan; WANG Jin-ying

    2004-01-01

    The radical transport of chemical concentration in porous media with dispersion and adsorption was studied in this paper. Using Langmuir's adsorption model, the numerical equation of concentration transport was derived. The flows with and without adsorption were simulated and analyzed.Comparison of the obtained solution with the known analytical solution for flow without adsorption shows the presented numerical method is correct and effective, which can be used in reservoir engineering.

  3. Water adsorption in hydrophilic zeolites: experiment and simulation

    OpenAIRE

    Castillo, Juan Manuel; Silvestre Albero, Joaquín; Rodríguez Reinoso, Francisco; Vlugt, Thijs. J. H.; Calero, Sofía

    2013-01-01

    We have measured experimental adsorption isotherms of water in zeolite LTA4A, and studied the regeneration process by performing subsequent adsorption cycles after degassing at different temperatures. We observed incomplete desorption at low temperatures, and cation rearrangement at successive adsorption cycles. We also developed a new molecular simulation force field able to reproduce experimental adsorption isotherms in the range of temperatures between 273 K and 374 K. Small deviations obs...

  4. Adsorption component of the disjoining pressure in thin liquid films

    OpenAIRE

    Tsekov, R.

    2011-01-01

    The disjoining pressure isotherm in foam films is theoretically studied and an important contribution of adsorption is discovered. On the basis of the interfacial thermodynamics an adsorption disjoining pressure component is derived, which is repulsive and exponentially decaying by the film thickness. Expressions for its magnitude and decay length are derived in terms of well-known thermodynamic characteristics such as the partial Gibbs elasticity and adsorption length. Several adsorption iso...

  5. Steps in Researching the Music in Therapy

    DEFF Research Database (Denmark)

    Bonde, Lars Ole

    2007-01-01

    The chapter introduces a generic flowchart + step-by-step guide for microanalysis of music (compositions and improvisations) in music therapy.......The chapter introduces a generic flowchart + step-by-step guide for microanalysis of music (compositions and improvisations) in music therapy....

  6. Hydraulic Design of Stepped Spillways Workshop

    Science.gov (United States)

    Stepped chutes and spillways are commonly used for routing discharges during flood events. In addition, stepped chutes are used for overtopping protection of earthen embankments. Stepped spillways provide significant energy dissipation due to its stepped feature; as a result, the stilling basin as...

  7. Polyethyleneimine assisted-two-step polymerization to develop surface imprinted cryogels for lysozyme purification.

    Science.gov (United States)

    Erol, Kadir; Köse, Kazım; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

    2016-10-01

    Surface imprinting strategy is one of the promising approaches to synthesize plastic antibodies while overcoming the problems in the protein imprinting research. In this study, we focused our attentions on developing two-step polymerization to imprint on the bare surface employing polyethyleneimine (PEI) assisted-coordination of template molecules, lysozyme. For this aim, we firstly synthesized poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA) cryogels as a bare structure. Then, we immobilized PEI onto the cryogels through the addition reaction between GMA and PEI molecules. After that, we determined the amount of free amine (NH2) groups of PEI molecules, subsequently immobilized methacrylate functionalities onto the half of them and another half was used to chelate Cu(II) ions as a mediator between template, lysozyme and PEI groups. After the characterization of the materials developed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and the micro-computed tomography (μCT), we optimized the lysozyme adsorption conditions from aqueous solution. Before performing lysozyme purification from chicken egg white, we evaluated the effects of pH, interaction time, the initial lysozyme concentration, temperature and ionic strength on the lysozyme adsorption. Moreover, the selectivity of surface imprinted cryogels was examined against cytochrome c and bovine serum albumin (BSA) as the competitors. Finally, the mathematical modeling, which was applied to describe the adsorption process, showed that the experimental data is very well-fitted to the Langmuir adsorption isotherm. PMID:27424087

  8. Improvement of soluble coffee aroma using an integrated process of supercritical CO2 extraction with selective removal of the pungent volatiles by adsorption on activates carbon

    Directory of Open Access Journals (Sweden)

    S. Lucas

    2006-06-01

    Full Text Available In this paper a two-step integrated process consisting of CO2 supercritical extraction of volatile coffee compounds (the most valuable from roasted and milled coffee, and a subsequent step of selective removal of pungent volatiles by adsorption on activated carbon is presented. Some experiments were carried out with key compounds from roasted coffee aroma in order to study the adsorption step: ethyl acetate as a desirable compound and furfural as a pungent component. Operational parameters such as adsorption pressure and temperature and CO2 flowrate were optimized. Experiments were conducted at adsorption pressures of 12-17 MPa, adsorption temperatures of 35-50ºC and a solvent flow rate of 3-5 kg/h. In all cases, the solute concentration and the activated particle size were kept constant. Results show that low pressures (12 MPa, low temperatures (35ºC and low CO2 flowrates (3 kg/h are suitable for removing the undesirable pungent and smell components (e.g. furfural and retaining the desirable aroma compounds (e.g. ethyl acetate. The later operation with real roasted coffee has corroborated the previous results obtained with the key compounds.

  9. Adsorption thermodynamics of macroporous resin adsorbing paeoniflorin%大孔树脂吸附芍药苷的吸附热力学研究

    Institute of Scientific and Technical Information of China (English)

    王玥; 杜守颖; 徐冰

    2011-01-01

    in Mudanpi, which was better than other types of macroporous resin. Its equilibrium adsorption data for paeoniflorin was accorded with Freundlich adsorption isothermal equation. The adsorption course was determined as an endothelium process when equilibrium adsorption coefficient increased with the rise of temperature and adsorption enthalpy was larger than zero. The adsorption course was determined as a spontaneous process when characteristic constant was larger than 1 and adsorption free energy was smaller than zero. When adsorption enthalpy was smaller than 40, a process of physical adsorption accompanied by hydrogen bonding adsorption occurred. Conclusion The parameters of thermodynamics has showed that the rise oftemperature is beneficial to the adsorption process of HPD200A macroporous resin. During industrial production, the extractive solution, while it is hot, can be purified by macroporous resin for saving cooling steps and increasing the amount of adsorption.

  10. Phenomenological study of monomer adsorption on fcc (335) surfaces with application to CO, O, and N(2) adsorption on Pt(335).

    Science.gov (United States)

    Phares, Alain J; Grumbine, David W; Wunderlich, Francis J

    2009-01-20

    We extend our recent study of adsorption on fcc (112) to fcc (335) surfaces, still considering only first- and second-neighbor interactions with repulsive first-neighbors. We consider the adsorbate-substrate interaction on the step sites of one of the two edges of the infinitely long terraces to be different from that on the remaining sites. The adsorption features on fcc (335) surfaces are richer than those on fcc (112), which can be attributed to the fact that the equilateral triangular terraces are now four-atoms wide rather than three. Our approach is independent of the chemical composition of the substrate and adsorbates and consequently may be applied to a variety of adsorption systems on fcc (335) surfaces which satisfy the limitations of our model. The basic question that our phenomenological approach intends to answer is: what are the constraints that can be obtained on the interaction energies from the experimental observation of one or more phases? This question is answered in the cases of CO, O, and N(2) adsorbed on Pt(335).

  11. What Promotes Wisdom in 12-Step Recovery?

    Science.gov (United States)

    DiGangi, Julia A; Majer, John M; Mendoza, Leslie; Droege, Jocelyn R; Jason, Leonard A; Contreras, Richard

    2014-01-01

    Research investigations on twelve-step groups such as Alcoholics Anonymous (AA) and Narcotics Anonymous (NA) have addressed a number of resources associated with 12-step recovery. However, little is known about the role of wisdom, and whether aspects of 12-step participation might increase this resource among 12-step members. An exploratory analysis revealed that participants who reported having a "spiritual awakening" and considered themselves "members" of 12-step groups reported significantly higher levels of wisdom. Twelve-step meeting attendance was not significantly related to wisdom scores. Findings suggest certain aspects of 12-step involvement are associated with wisdom and may play a role in substance abuse recovery.

  12. Adsorption and cometabolic bioregeneration in activated carbon treatment of 2-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, Ozguer, E-mail: Ozgur.Aktas@mam.gov.tr [Bogazici University Institute of Environmental Sciences, 34342 Bebek, Istanbul (Turkey); Cecen, Ferhan [Bogazici University Institute of Environmental Sciences, 34342 Bebek, Istanbul (Turkey)

    2010-05-15

    The extent of cometabolic bioregeneration of activated carbons loaded with 2-nitrophenol was investigated in lab-scale batch activated sludge reactors. Bioregeneration was quantified by measuring the deterioration in adsorption capacity of a fresh activated carbon after a pre-loading and a subsequent bioregeneration sequence. Activated carbons loaded with 2-nitrophenol could be partially bioregenerated cometabolically in the presence of phenol as the growth substrate. The occurrence of exoenzymatic bioregeneration was also possible during cometabolic bioregeneration of thermally activated carbon. However, cometabolic bioregeneration of chemically activated carbon was higher in accordance with higher desorbability. Rather than biodegradation, desorption was the rate-limiting step in bi-solute bioregeneration of phenol and 2-nitrophenol. The absence of oxidative coupling reactions leads to sufficient reversible adsorption, which eventually makes 2-nitrophenol an ideal compound in terms of bioregenerability.

  13. Kinetics of oxygen adsorption on ZnS nanoparticles synthesized by precipitation process

    Directory of Open Access Journals (Sweden)

    Ahmadi Reza

    2016-06-01

    Full Text Available ZnS nanoparticles were synthesized through a one-step precipitation process. Effect of time and temperature on the formation reaction was investigated. The synthesized samples were characterized by X-ray diffraction (XRD, ultraviolet (UV visible absorption and photoluminescence (PL spectrophotometry. Based on XRD and UV-Vis data, the particles produced at 70 °C had a mean particle size of about 5 nm. Increasing time and temperature of the synthesis reaction resulted in photoluminescence intensification. PL spectroscopy helped understanding the adsorption kinetics of oxygen on ZnS nanoparticles during the precipitation synthesis process. Fabrication of ZnS structures with appropriate oxygen adsorption capacity was suggested as a means of PL emission intensity control.

  14. Synthesis and uranium adsorption performance of a novel modified lignin-based adsorbent

    International Nuclear Information System (INIS)

    The modified lignin-based adsorbent containing the strong-base and weak-base group, was prepared by two-step chemical modification of acid-precipitation lignin, which is low-cost, and abundant renewable natural polymers: (1) introduced weak-base group by mannich reaction; (2)introduced strong-base group by O-alkylatio reaction.The adsorbent was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Elementary Analysis(EA), which demonstrated amino group was successfully introduced into the lignin. In order to assess the possibility of adsorption effect, the adsorption experiments of uranium on lignin-based adsorbent, were carried out in the static mode at room temperature. The removal rate of uranium of the wastewatere could reach 93%, under such conditions as pH value 2, uranium concentration 6 mg/L, and adsorbent dosage 10 g/L, etc. (authors)

  15. Synthesis and uranium adsorption performance of a novel modified lignin-based adsorbent

    International Nuclear Information System (INIS)

    The modified lignin-based adsorbent containing the strong-base and weak-base group, was prepared by two-step chemical modification of acid-precipitation lignin, which is a low-cost and abundant renewable natural polymer: 1) weak-base group introduced by Mannich reaction; 2) strong-base group introduced by O-alkylation reaction. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and elementary analysis (EA), which demonstrated amino group was successfully introduced into the lignin. In order to assess the adsorption effect, the uranium adsorption experiments of lignin-based adsorbent were carried out in the static mode at room temperature. The removal rate of uranium from the wastewater could reach 93% under such conditions as pH value 2, uranium concentration 6 mg/L, adsorbent dosage 10 g/L etc. (authors)

  16. Dissociative Carbon Dioxide Adsorption and Morphological Changes on Cu(100) and Cu(111) at Ambient Pressures.

    Science.gov (United States)

    Eren, Baran; Weatherup, Robert S; Liakakos, Nikos; Somorjai, Gabor A; Salmeron, Miquel

    2016-07-01

    Ambient-pressure X-ray photoelectron spectroscopy (APXPS) and high-pressure scanning tunneling microscopy (HPSTM) were used to study the structure and chemistry of model Cu(100) and Cu(111) catalyst surfaces in the adsorption and dissociation of CO2. It was found that the (100) face is more active in dissociating CO2 than the (111) face. Atomic oxygen formed after the dissociation of CO2 poisons the surface by blocking further adsorption of CO2. This "self-poisoning" mechanism explains the need to mix CO into the industrial feed for methanol production from CO2, as it scavenges the chemisorbed O. The HPSTM images show that the (100) surface breaks up into nanoclusters in the presence of CO2 at 20 Torr and above, producing active kink and step sites. If the surface is precovered with atomic oxygen, no such nanoclustering occurs. PMID:27280375

  17. Mechanisms on formation of hierarchically porous carbon and its adsorption behaviors.

    Science.gov (United States)

    Liu, Jie; Hao, Lingxia; Qian, Wenzhen; He, Yu-Feng; Wang, Rong-Min

    2016-01-01

    Using simple one-step carbonization-activation, the residues of paulownia flowers are employed as a precursor to prepare hierarchically porous activated carbon. After investigating the optimum conditions, the obtained paulownia flowers based activated carbon (PFAC) is characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, Brunauer-Emmett-Teller specific surface area analysis (S(BET)), thermo gravimetric analysis, and X-ray photoelectron spectroscopy. The PFAC owns a high specific surface area of 1,053 m(2)/g as well as a hierarchically porous structure with a combination of micro-, meso- and macropores. The pore-forming mechanism is discussed according to results of characterization. Using methylene blue as model dye, the adsorption behaviors of PFAC were investigated. We found that the dye could be rapidly adsorbed by hierarchically porous PFAC, and the adsorption capacity of PFAC reached 300 mg/g. PMID:27387005

  18. Adsorption modeling for off-gas treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ladshaw, A.; Sharma, K.; Yiacoumi, S.; Tsouris, C. [Georgia Institute of Technology, Atlanta, GA 30332-0459 (United States); De Paoli, D.W. [Oak Ridge National Laboratory: Oak Ridge, TN 37831-6181 (United States)

    2013-07-01

    Off-gas generated from the reprocessing of used nuclear fuel contains a mixture of several radioactive gases including {sup 129}I{sub 2}, {sup 85}Kr, HTO, and {sup 14}CO{sub 2}. Over the past few decades, various separation and recovery processes have been studied for capturing these gases. Adsorption data for gaseous mixtures of species can be difficult to determine experimentally. Therefore, procedures capable of predicting the adsorption behavior of mixtures need to be developed from the individual isotherms of each of the pure species. A particular isotherm model of interest for the pure species is the Generalized Statistical Thermodynamic Adsorption isotherm. This model contains an adjustable number of parameters and will therefore describe a wide range of adsorption isotherms for a variety of components. A code has been developed in C++ to perform the non-linear regression analysis necessary for the determination of the isotherm parameters, as well as the least number of parameters needed to describe an entire set of data. (authors)

  19. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, WTE; Iakovlev, PA; Norde, W; Stuart, Martien A. Cohen

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N = 770) and short (N = 48) PEO chains and were prepared on PS surfaces, applying mixtures of PS29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodg

  20. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, W.T.E.; Iakovlev, P.A.; Norde, W.; Cohen Stuart, M.A.

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N=770) and short (N=48) PEO chains and were prepared on PS surfaces, applying mixtures of PS 29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodgett

  1. Optimization of Adsorptive Immobilization of Alcohol Dehydrogenases

    NARCIS (Netherlands)

    Trivedi, Archana; Heinemann, Matthias; Spiess, Antje C.; Daussmann, Thomas; Büchs, Jochen

    2005-01-01

    In this work, a systematic examination of various parameters of adsorptive immobilization of alcohol dehydrogenases (ADHs) on solid support is performed and the impact of these parameters on immobilization efficiency is studied. Depending on the source of the enzymes, these parameters differently in

  2. Adsorption Kinetics in Nanoscale Porous Coordination Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Nune, Satish K.; Thallapally, Praveen K.; McGrail, Benard Peter; Annapureddy, Harsha V. R.; Dang, Liem X.; Mei, Donghai; Karri, Naveen; Alvine, Kyle J.; Olszta, Matthew J.; Arey, Bruce W.; Dohnalkova, Alice

    2015-10-07

    Nanoscale porous coordination polymers were synthesized using simple wet chemical method. The effect of various polymer surfactants on colloidal stability and shape selectivity was investigated. Our results suggest that the nanoparticles exhibited significantly improved adsorption kinetics compared to bulk crystals due to decreased diffusion path lengths and preferred crystal plane interaction.

  3. Theoretical study of cisplatin adsorption on silica

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Company, A. Diaz; Brizuela, G.; Juan, A. [Departamento de Fisica and IFISUR, Universidad Nacional del Sur-CONICET, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

    2011-11-15

    The adsorption of cisplatin and its complexes, cis-[PtCl(NH{sub 3}){sub 2}]{sup +} and cis-[Pt(NH{sub 3}){sub 2}]{sup 2+}, on a SiO{sub 2}(1 1 1) hydrated surface has been studied by the Atom Superposition and Electron Delocalization method. The adiabatic energy curves for the adsorption of the drug and its products on the delivery system were considered. The electronic structure and bonding analysis were also performed. The molecule-surface interactions are formed at expenses of the OH surface bonds. The more important interactions are the Cl-H bond for cis-[PtCl{sub 2}(NH{sub 3}){sub 2}] and cis-[PtCl(NH{sub 3}){sub 2}]{sup +} adsorptions, and the Pt-O interaction for cis-[Pt(NH{sub 3}){sub 2}]{sup 2+} adsorption. The Cl p orbitals and Pt s, p y d orbitals of the molecule and its complexes, and the s H orbital and, the s and p orbitals of the O atoms of the hydrated surface are the main contribution to the surface bonds.

  4. Adsorption Properties of Chalk Reservoir Materials

    DEFF Research Database (Denmark)

    Okhrimenko, Denis

    Understanding adsorption energetics and wetting properties of calcium carbonate surfaces is essential for developing remediation strategies for aquifers, improving oil recovery, minimising risk in CO2 storage and optimising industrial processes. This PhD was focussed on comparing the vapour...

  5. Adsorption Phenomena at Organic-Inorganic Interfaces

    OpenAIRE

    Bachmann, M.; Janke, W.

    2007-01-01

    The qualitative solvent- and temperature-dependent conformational behavior of a peptide in the proximity of solid substrates with different adsorption properties is investigated by means of a simple lattice model. The resulting pseudophase diagrams exhibit a complex structure, which can be understood by analysing the minima of the free-energy landscape in dependence of appropriate system parameters.

  6. Fluorocarbon adsorption in hierarchical porous frameworks

    Science.gov (United States)

    Motkuri, Radha Kishan; Annapureddy, Harsha V. R.; Vijaykumar, M.; Schaef, H. Todd; Martin, Paul F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-01

    Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g-1 at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g-1 at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

  7. Adsorption of penicillin by decaffeinated tea waste

    Directory of Open Access Journals (Sweden)

    Gharbani Parvin

    2015-09-01

    Full Text Available Removal of penicillin has been investigated using decaffeinated tea waste (DCTW. Decaffeination of tea waste was investigated using different methods. Results indicate that ozonation was the most effective process for removal of penicillin. Batch adsorption experiments were completed at various temperatures (20, 30, and 40°C, DCTW dosages (2, 4, 6, 8, and 10 g per 250 mL, penicillin concentrations (4, 10, and 14 mg/L, and pH (3, 7, and 10 conditions. Studies showed that adsorption reaches equilibrium within 40 min. The main factor affecting adsorption of penicillin was the solution pH, with maximum adsorption occurring at pH 3. Higher adsorbent dosages and lower penicillin concentrations also resulted in higher percentages of penicillin removal. Results show that data obeyed the pseudo-first-order kinetic and Freundlich isotherm models. This process proves that low-cost DCTW could be used as a high performance adsorbent for removing penicillin from aqueous solutions.

  8. Modeling the Adsorption of Oxalate onto Montmorillonite.

    Science.gov (United States)

    Ramos, M Elena; Emiroglu, Caglayan; García, David; Sainz-Díaz, C Ignacio; Huertas, F Javier

    2015-11-01

    In this work, a multiscale modeling of the interaction of oxalate with clay mineral surfaces from macroscale thermodynamic equilibria simulations to atomistic calculations is presented. Previous results from macroscopic adsorption data of oxalate on montmorillonite in 0.01 M KNO3 media at 25 °C within the pH range from 2.5 to 9 have been used to develop a surface complexation model. The experimental adsorption edge data were fitted using the triple-layer model (TLM) with the aid of the FITEQL 4.0 computer program. Surface complexation of oxalate is described by two reactions: >AlOH + Ox(2-) + 2H(+) = >AlOxH + H2O (log K = 14.39) and >AlOH + Ox(2-) + H(+) = >AlOx(-) + H2O (log K = 10.39). The monodentate complex >AlOxH dominated adsorption below pH 4, and the bidentate complex >AlOx(-) was predominant at higher pH values. Both of the proposed inner-sphere oxalate species are qualitatively consistent with previously published diffuse reflectance FTIR spectroscopic results for oxalate on montmorillonite edge surface (Chem. Geol. 2014, 363, 283-292). Atomistic computational studies have been performed to understand the interactions at the molecular level between adsorbates and mineral surface, showing the atomic structures and IR frequency shifts of the adsorption complexes of oxalate with the edge surface of a periodic montmorillonite model. PMID:26444928

  9. Modeling adsorption with lattice Boltzmann equation.

    Science.gov (United States)

    Guo, Long; Xiao, Lizhi; Shan, Xiaowen; Zhang, Xiaoling

    2016-01-01

    The research of adsorption theory has recently gained renewed attention due to its critical relevance to a number of trending industrial applications, hydrogen storage and shale gas exploration for instance. The existing theoretical foundation, laid mostly in the early twentieth century, was largely based on simple heuristic molecular interaction models and static interaction potential which, although being insightful in illuminating the fundamental mechanisms, are insufficient for computations with realistic adsorbent structure and adsorbate hydrodynamics, both critical for real-life applications. Here we present and validate a novel lattice Boltzmann model incorporating both adsorbate-adsorbate and adsorbate-adsorbent interactions with hydrodynamics which, for the first time, allows adsorption to be computed with real-life details. Connection with the classic Ono-Kondo lattice theory is established and various adsorption isotherms, both within and beyond the IUPAC classification are observed as a pseudo-potential is varied. This new approach not only enables an important physical to be simulated for real-life applications, but also provides an enabling theoretical framework within which the fundamentals of adsorption can be studied. PMID:27256325

  10. Modeling adsorption with lattice Boltzmann equation

    Science.gov (United States)

    Guo, Long; Xiao, Lizhi; Shan, Xiaowen; Zhang, Xiaoling

    2016-01-01

    The research of adsorption theory has recently gained renewed attention due to its critical relevance to a number of trending industrial applications, hydrogen storage and shale gas exploration for instance. The existing theoretical foundation, laid mostly in the early twentieth century, was largely based on simple heuristic molecular interaction models and static interaction potential which, although being insightful in illuminating the fundamental mechanisms, are insufficient for computations with realistic adsorbent structure and adsorbate hydrodynamics, both critical for real-life applications. Here we present and validate a novel lattice Boltzmann model incorporating both adsorbate-adsorbate and adsorbate-adsorbent interactions with hydrodynamics which, for the first time, allows adsorption to be computed with real-life details. Connection with the classic Ono-Kondo lattice theory is established and various adsorption isotherms, both within and beyond the IUPAC classification are observed as a pseudo-potential is varied. This new approach not only enables an important physical to be simulated for real-life applications, but also provides an enabling theoretical framework within which the fundamentals of adsorption can be studied. PMID:27256325

  11. Adsorption and desorption of cellulose derivatives.

    NARCIS (Netherlands)

    Hoogendam, C.W.

    1998-01-01

    Cellulose derivatives, in particular carboxymethyl cellulose (CMC) are used in many (industrial) applications. The aim of this work is to obtain insight into the adsorption mechanism of cellulose derivatives on solid-liquid interfaces.In chapter 1 of this thesis we discuss some appl

  12. Adsorption of Ions at Uncharged Insoluble Monolayers

    Science.gov (United States)

    Peshkova, T. V.; Minkov, I. L.; Tsekov, R.; Slavchov, R. I.

    2016-08-01

    A method is proposed for the experimental determination of the adsorption of inorganic electrolytes at a surface covered with insoluble surfactant monolayer. This task is complicated by the fact that the change of the salt concentration alters both chemical potentials of the electrolyte and the surfactant. Our method resolves the question by combining data for the surface pressure versus area of the monolayer at several salt concentrations with data for the equilibrium spreading pressure of crystals of the surfactant (used to fix a standard state). We applied the method to alcohols spread at the surface of concentrated halide solutions. The measured salt adsorption is positive and has nonmonotonic dependence on the area per surfactant molecule. For the liquid expanded film, depending on the concentration, there is one couple of ions adsorbed per each 3–30 surfactant molecules. We analyzed which ion, the positive or the negative, stands closer to the surface, by measuring the effect of NaCl on the Volta potential of the monolayer. The potentiometric data suggest that Na+ is specifically adsorbed, while Cl– remains in the diffuse layer, i.e., the surface is positively charged. The observed reverse Hofmeister series of the adsorptions of NaF, NaCl, and NaBr suggests the same conclusion holds for all these salts. The force that causes the adsorption of Na+ seems to be the interaction of the ion with the dipole moment of the monolayer.

  13. Exhaustively sampling peptide adsorption with metadynamics.

    Science.gov (United States)

    Deighan, Michael; Pfaendtner, Jim

    2013-06-25

    Simulating the adsorption of a peptide or protein and obtaining quantitative estimates of thermodynamic observables remains challenging for many reasons. One reason is the dearth of molecular scale experimental data available for validating such computational models. We also lack simulation methodologies that effectively address the dual challenges of simulating protein adsorption: overcoming strong surface binding and sampling conformational changes. Unbiased classical simulations do not address either of these challenges. Previous attempts that apply enhanced sampling generally focus on only one of the two issues, leaving the other to chance or brute force computing. To improve our ability to accurately resolve adsorbed protein orientation and conformational states, we have applied the Parallel Tempering Metadynamics in the Well-Tempered Ensemble (PTMetaD-WTE) method to several explicitly solvated protein/surface systems. We simulated the adsorption behavior of two peptides, LKα14 and LKβ15, onto two self-assembled monolayer (SAM) surfaces with carboxyl and methyl terminal functionalities. PTMetaD-WTE proved effective at achieving rapid convergence of the simulations, whose results elucidated different aspects of peptide adsorption including: binding free energies, side chain orientations, and preferred conformations. We investigated how specific molecular features of the surface/protein interface change the shape of the multidimensional peptide binding free energy landscape. Additionally, we compared our enhanced sampling technique with umbrella sampling and also evaluated three commonly used molecular dynamics force fields. PMID:23706011

  14. The computational study of adsorption of carbon monoxide on pristine and Ge-doped (6,0 zigzag models of BNNTs

    Directory of Open Access Journals (Sweden)

    Mahdi Rezaei Sameti

    2014-07-01

    Full Text Available The aim of this research is studying the effects of Ge-doped on CO adsorption on the outer and inner surfaces of (6, 0 zigzag model of boron nitride nanotube (BNNTs by using DFT theory. For this purpose, eight models of CO adsorption on the surfaces of BNNTs are considered. At first step, all structures were optimized at B3LYP and 6-31G (d standard base set and then the electronic structure, adsorption energy, HOMO - LUMO orbitals, gap energy, quantum molecular descriptors, and NQR parameters were determined. The bond lengths neighborhood sites of Ge-doped of BNNTs at all models were increased and the bond angles decreased. The small ad-sorption energy value and large interaction distance show that the adsorption of CO on BNNTs is weakly physical adsorption due to weak Van der Waals interaction. Our calculated results show that the adsorption of CO on the surface of undoped models is more favorable than Ge-doped models. The NQR parameters of the first layer in all the models are larger than those other layers.

  15. Effect of copper stress on growth characteristics and fermentation properties of Saccharomyces cerevisiae and the pathway of copper adsorption during wine fermentation.

    Science.gov (United States)

    Sun, Xiangyu; Liu, Lingling; Zhao, Yu; Ma, Tingting; Zhao, Fang; Huang, Weidong; Zhan, Jicheng

    2016-02-01

    The effect of copper stress on the fermentation performance of Saccharomyces cerevisiae and its copper adsorption pathway during alcoholic fermentation were investigated in this study. At the limits imposed by the regulations of the European Union and South African (⩽ 20 mg/l), copper had no effect on the cell growth of S. cerevisiae, but its fermentation performance was inhibited to a certain extent. Therefore, the regulated limit should be further reduced (⩽ 12.8 mg/l). Under 9.6-19.2 mg/l copper stress, S. cerevisiae could absorb copper; the copper removal ratio and the unit strain adsorption were 60-81% and 2.72-9.65 mg/g, respectively. S. cerevisiae has a non-biological adsorption of copper, but compared with biological (living yeast) adsorption, the non-biological adsorption was very low. The copper adsorption way of S. cerevisiae was primarily via biological (living yeast) adsorption, which was a two-step process.

  16. Dye adsorption mechanisms in TiO2 films, and their effects on the photodynamic and photovoltaic properties in dye-sensitized solar cells.

    Science.gov (United States)

    Hwang, Kyung-Jun; Shim, Wang-Geun; Kim, Youngjin; Kim, Gunwoo; Choi, Chulmin; Kang, Sang Ook; Cho, Dae Won

    2015-09-14

    The adsorption mechanism for the N719 dye on a TiO2 electrode was examined by the kinetic and diffusion models (pseudo-first order, pseudo-second order, and intra-particle diffusion models). Among these methods, the observed adsorption kinetics are well-described using the pseudo-second order model. Moreover, the film diffusion process was the main controlling step of adsorption, which was analysed using a diffusion-based model. The photodynamic properties in dye-sensitized solar cells (DSSCs) were investigated using time-resolved transient absorption techniques. The photodynamics of the oxidized N719 species were shown to be dependent on the adsorption time, and also the adsorbed concentration of N719. The photovoltaic parameters (Jsc, Voc, FF and η) of this DSSC were determined in terms of the dye adsorption amounts. The solar cell performance correlates significantly with charge recombination and dye regeneration dynamics, which are also affected by the dye adsorption amounts. Therefore, the photovoltaic performance of this DSSC can be interpreted in terms of the adsorption kinetics and the photodynamics of oxidized N719.

  17. Adsorption behaviors of a novel carbonyl and hydroxyl groups modified hyper-cross-linked poly(styrene-co-divinylbenzene) resin for beta-naphthol from aqueous solution.

    Science.gov (United States)

    He, Chunlian; Huang, Jianhan; Yan, Cheng; Liu, Jianbo; Deng, Linbei; Huang, Kelong

    2010-08-15

    A series of novel hyper-cross-linked resins were synthesized from macroporous cross-linked chloromethylated poly(styrene-co-divinylbenzene) by adding different dosage of hydroquinone in Friedel-Crafts reaction. The results of the pore structures revealed that the prepared resins possessed micropores, mesopores and macropores, and the chloromethyl groups and the uploaded hydroquinone were partly oxidized according to the results of Fourier-transformed infrared ray spectra. Among these hydroquinone modified resins, HJ-Y06 resin held the largest adsorption capacity for beta-naphthol, and its adsorption capacity was comparable with XAD-4 while much larger than X-5. The adsorption kinetics could be characterized by pseudo-second-order rate equation and intra-particle diffusion model was the rate-limiting step at the initial process. The adsorption was favorable at solution pH lower than 6.5. The adsorption isotherms could be fitted by Langmuir model and the adsorption was an endothermic process. Hydrogen bonding between formaldehyde carbonyl and quinone carbonyl groups on HJ-Y06 and phenolic hydroxyl groups of beta-naphthol was the main driving force for the adsorption.

  18. Water adsorption on the Be(0001) surface:from monomer to trimer adsorption

    Institute of Scientific and Technical Information of China (English)

    Ning Hua; Tao Xiang-Ming; Tan Ming-Qiu

    2012-01-01

    In this paper,the density functional theory has been used to perform a comparative theoretical study of water monomer,dimer,trimer,and bilayer adsorptions on the Be(0001) surface. In our calculations,the adsorbed water molecules are energetically favoured adsorbed on the atop sites,and the dimer adsorption is found to be the most stable with a peak adsorption energy of ~ 437 meV.Further analyses have revealed that the essential bonding interaction between the water monomer and the metal substrate is the hybridization of the water 3a1-like molecular orbital with the (s,pz) orbitals of the surface beryllium atoms.While in the case of the water dimer adsorption,the lb1-like orbital of the H2O molecule plays a dominant role.

  19. Polyglycidyl methacrylate based immunoaffinity cryogels for insulin adsorption

    International Nuclear Information System (INIS)

    Immunoaffinity chromatography (IAC) is a kind of bioaffinity chromatography which used antibodies or antibody-related molecules as the stationary phase. IAC is used by many applications for analytical, clinical and diagnostic purposes, particularly preferring in analytical purposes on one-step separation and purification of target compounds. Moreover, immunoaffinity chromatography is used in antibody enrichment and separation of cells. IAC columns are usually applied in the antibody experiments due to powerful and selective binding of antibodies and/or their target antigens. Antigen or antibody molecules could be immobilized to the solid support. Therefore, target antibody or cell is purified. Specific bioligands can be immobilized directly on glycidyl based polymeric material with simple acid–base catalyst. In this study, polyglycidyl methacrylate based therefore cryogels were prepared and anti-insulin antibodies were immobilized on porous surface of cryogels. Swelling test, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) were conducted to characterize cryogels developed. To optimize separation conditions, effects of pH, initial insulin concentration, flow rate, salt concentration, contact time and temperature on insulin adsorption capacity were examined. The results indicated that the immunoaffinity cryogel developed here could be classified as good alternative with prominent properties such as high reusability and cost-friendly adsorbent and would be one of the primary reports for immunoaffinity purification of insulin molecules in not only lab-scale but also for industrial purposes. - Highlights: • Polyglycidyl methacrylate based cryogels developed as stationary phase • Immunoaffinity cryogels for reusable and cost-friendly insulin adsorption • Increase in worldwide prevalence of diabetes, type 1 or 2 • An exponential increase in the demand on insulin market • Guiding researchers for not

  20. Polyglycidyl methacrylate based immunoaffinity cryogels for insulin adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Memmedova, Türkan; Armutcu, Canan; Uzun, Lokman, E-mail: lokman@hacettepe.edu.tr; Denizli, Adil

    2015-07-01

    Immunoaffinity chromatography (IAC) is a kind of bioaffinity chromatography which used antibodies or antibody-related molecules as the stationary phase. IAC is used by many applications for analytical, clinical and diagnostic purposes, particularly preferring in analytical purposes on one-step separation and purification of target compounds. Moreover, immunoaffinity chromatography is used in antibody enrichment and separation of cells. IAC columns are usually applied in the antibody experiments due to powerful and selective binding of antibodies and/or their target antigens. Antigen or antibody molecules could be immobilized to the solid support. Therefore, target antibody or cell is purified. Specific bioligands can be immobilized directly on glycidyl based polymeric material with simple acid–base catalyst. In this study, polyglycidyl methacrylate based therefore cryogels were prepared and anti-insulin antibodies were immobilized on porous surface of cryogels. Swelling test, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) were conducted to characterize cryogels developed. To optimize separation conditions, effects of pH, initial insulin concentration, flow rate, salt concentration, contact time and temperature on insulin adsorption capacity were examined. The results indicated that the immunoaffinity cryogel developed here could be classified as good alternative with prominent properties such as high reusability and cost-friendly adsorbent and would be one of the primary reports for immunoaffinity purification of insulin molecules in not only lab-scale but also for industrial purposes. - Highlights: • Polyglycidyl methacrylate based cryogels developed as stationary phase • Immunoaffinity cryogels for reusable and cost-friendly insulin adsorption • Increase in worldwide prevalence of diabetes, type 1 or 2 • An exponential increase in the demand on insulin market • Guiding researchers for not

  1. Stepped conical zone plate antenna

    Science.gov (United States)

    Wiltse, James C.

    2001-07-01

    The Fresnel zone plate lens was invented and developed for optical frequencies. However, fabrication difficulties at the short optical wavelengths have prevented obtain good efficiencies. At longer microwave or millimeter-wavelengths fabrication is easier and phase correcting zone plate antennas have been used to obtain good efficiencies. This paper describes a new type of phase correcting zone plate having even better efficiency, namely a diffraction efficiency of 99 percent compared to a true lens, and an overall efficiency much better than a true lens. For the usual zone plate antenna employed at microwave or millimeter wavelengths, path length adjustment is accomplished by cutting different depths in a dielectric plate or by using two or more dielectrics having different dielectric constants. The new design uses a tilted cut in a dielectric plate, which more accurately matches the shape of a true lens and produces much lower phase error. The construction is still near and can be made for example, by a milling machine with a tilted bit. For a circular zone plate, the lens is a stepped conical or tapered shape. Because the phase steps are small, the far-field antenna pattern is excellent and sidelobe-levels are very low. Analysis of typical configurations will be given, showing that phase errors are small, lower than those for an eighth-wave corrected phase zone plate.

  2. Adsorption materials for the recovery and separation of biobased molecules

    NARCIS (Netherlands)

    IJzer, Anne Corine

    2016-01-01

    In this thesis we studied several strategies to improve adsorption technology for the adsorption of biobased molecules. These strategies are based on the adsorbent as well as the adsorption process. A systematic investigation of the chemical and physical structure of resin materials and their relati

  3. ADSORPTION OF GOLD ON TBP EXTRACTING RESIN FROM HCl SOLUTION

    Institute of Scientific and Technical Information of China (English)

    GaoHaoqi; CaoZhikai; 等

    1998-01-01

    Adsorption of gold on TBP extracting resin from HCl solution was researched.All the effects of factors,such as solution acidity,TBP content,temperature,etc.,on adsorption equilibrium were discussed and the equilibrium equation was formulated.The breakthough time of adsorption process with fixed bed was studied through experiment.

  4. Visualizing Gas Adsorption on Porous Solids: Four Simple, Effective Demonstrations

    Science.gov (United States)

    Cheung, Ocean

    2014-01-01

    Gas adsorption on porous solids is a topic that is often discussed in an undergraduate chemistry or chemical engineering course. The idea of porosity and gas adsorption on a porous solid is usually discussed with adsorption isotherms recorded using commercially available equipment. This discussion can be rather abstract and can be difficult for…

  5. Monte Carlo Simulation for the Adsorption of Symmetric Triblock Copolymers

    Institute of Scientific and Technical Information of China (English)

    彭昌军; 李健康; 刘洪来; 胡英

    2004-01-01

    The adsorption behavior of symmetric triblock copolymers, Am/2BnAm/2, from a nonselective solvent at solid-liquid interface has been studied by Monte Carlo simulations on a simple lattice model. Either segment A or segment B is attractive, while the other is non-attractive to the surface. Influences of the adsorption energy,bulk concentration, chain composition and chain length on the microstructure of adsorbed layers are presented.The results show that the total surface coverage and the adsorption amount increases monotonically as the bulk concentration increases. The larger the adsorption energy and the higher the fraction of adsorbing segments, the higher the total surface coverage is exhibited. The product of surface coverage and the proportion of non-attractive segments are nearly independent of the chain length, and the logarithm of the adsorption amount is a linear function of the reciprocal of the reduced temperature. When the adsorption energy is larger, the adsorption amount exhibits a maximum as the fraction of adsorbing segment increases. The adsorption isotherms of copolymers with different length of non-attractive segments can be mapped onto a single curve under given adsorption energy. The adsorption layer thickness decreases as the adsorption energy and the fraction of adsorbing segments increases, but it increhses as the length of non-attractive segments increases. The tails mainly govern the adsorption layer thickness.

  6. Competitive protein adsorption to polymer surface from human serum

    DEFF Research Database (Denmark)

    Holmberg, Maria; Jensen, Karin Bagger Stibius; Larsen, Niels Bent;

    2008-01-01

    and on the presence and concentration of other proteins in bulk solutions during adsorption. Generally, lower albumin and IgG adsorption was observed on the modified and more hydrophilic polymer surfaces, but otherwise the modified and unmodified polymer surfaces showed the same adsorption characteristics....

  7. Influence of adsorption properties on radionuclide transport in fractured rock

    International Nuclear Information System (INIS)

    Most models predicting radionuclide transport in fractured rock include mechanisms of advection, dispersion, radioactive decay, and equilibrium adsorption between the solid and liquid phases. Recently, nonequilibrium adsorption has been given a great deal of attention. In this paper, the authors have successfully derived the analytical solutions to transport equations for a single fracture under various conditions covering no sorption, nonequilibrium adsorption, and equilibrium sorption

  8. Adsorption of nonionic surfactants onto polystyrene : kinetics and reversibility

    NARCIS (Netherlands)

    Geffroy, C.; Cohen Stuart, M.A.; Wong, K.; Cabane, B.; Bergeron, V.

    2000-01-01

    The reversible adsorption and desorption kinetics of nonionic surfactants at a hydrophobic surface have been studied by reflectometry. This enables the measurement of the adsorption isotherm with unprecedented accuracy. It is shown that the adsorption mechanism can be split into three processes. The

  9. Adsorption isotherm of non-azeotropic solution onto porous adsorbents

    Science.gov (United States)

    Bono, A.; Ramlan, N. A.; Anisuzzaman, S. M.; Chu, C. M.; Farm, Y. Y.

    2016-06-01

    Adsorption isotherm is essential component in the understanding of the adsorption process. Several methods of the measurements, analysis and interpretation of adsorption from solution have been reported in the literature. Most of the measurements of adsorption isotherm from solution were involved the measurement of excess isotherm conducted at low region of sorbates concentration. Direct interpretation of excess adsorption isotherm as adsorption isotherm is always been practice. Therefore, in this work a study on the measurement of the adsorption isotherm from solution of non-azeotropic organic solvent mixture onto porous adsorbents for whole range of liquid concentration was conducted. The study included the measurement of excess adsorption isotherm using conventional technique. Theoretical analysis and interpretation of adsorption isotherm from the excess isotherm were conducted using Pseudo Ideal Adsorption, Gibbs Dividing Plane Model and Langmuir-Fruendlich binary isotherm model. For organic solvents, acetone and propanol were chosen as the adsorbates due to the non-azeotropic properties in the mixture. Activated carbon and silicalite were chosen as adsorbents due to the different in their porosity such as macro porous and micro porous structure. The result of the study has revealed that the adsorption isotherm of non-azeotropic mixture onto activated carbon and silicalite can be interpreted as monolayer type of adsorption.

  10. [Adsorption and Desorption Characteristics of Endosulfan in Purple Soil].

    Science.gov (United States)

    Zhao, Yan; Zheng, Guo-can; Zhu, Heng; Zhang, Jin-zhong; Zhu, Xiu-ying; Hu, Shu-chun; Wu, Ya-lin

    2015-09-01

    In order to reveal the residual process of endosulfan in purple soil and protect soil ecological environment, the adsorption and desorption characteristics of endosulfan in purple soil were investigated, and effects of temperature, adsorbent amount, and initial pH of adsorption solution on the adsorption capacity were also examined by static adsorption and desorption experiments. The results showed that the adsorption kinetic process could be well described by the second-order kinetic equation with the initial rate constants of α-, β-endosulfan as 0. 157 and 0. 115 mg.(g.min)-1, respectively. The adsorption thermodynamic process could be well described by the Langmuir isotherm with the maximum adsorption capacities of α-, β-endosulfan as 0. 257 mg . g -1 and 0. 155 mg . g -1, respectively. The adsorption process of endosulfan in purple soil may be an exothermic physicochemical process, and is dominated by physical adsorption. Under the experimental conditions examined in this study, the initial pH of adsorption solution had a relative great influence on the adsorption capacity, whereas the temperature and adsorbent amount had no significant influence. The desorption experiments found that the maximum desorption capacities of α-, β-endosulfan adsorbed in purple soil were 0. 029 mg . g -1 and 0. 017 mg . g -1 at 6 and 4 h, and accounted for 10. 5% and 16. 1% in the maximum adsorption capacities, respectively. PMID:26717711

  11. Adsorption of Pb(Ⅱ) on Sediment of the Dianshan Lake:Adsorption Models and Kinetics

    Institute of Scientific and Technical Information of China (English)

    黄莉桦; 孙为民

    2004-01-01

    The adsorption characteristics of Pb on sediments of the Dianshan Lake in Shanghai was studied. The results show that (1)the relationship between the amount q of apparent equilibrium adsorption and the equilibrium concentration C conforms to the Freundlich isothermal adsorption equation; (2) the adsorption and desorption of Pb on sediments are not reversible, that is, adsorption/desorption of Pb exhibits hysteresis; (3) Pb adsorption behavior is initially fast, followed by a slow reaction, and the slow reaction conforms to a reversible first-order reaction; (4) by deducing the Pb adsorption kinetics, four kinetics parameters n, k1, k2, qmax independent of C could be worked out; (5) the equilibrium parameter (K) and the free energy change (ΔG) could also be determined,and the negative values of free energy change (ΔG) indicate the spontaneous nature of the adsorption.

  12. The adsorption of HCl on volcanic ash

    Science.gov (United States)

    Gutiérrez, Xochilt; Schiavi, Federica; Keppler, Hans

    2016-03-01

    Understanding the interaction between volcanic gases and ash is important to derive gas compositions from ash leachates and to constrain the environmental impact of eruptions. Volcanic HCl could potentially damage the ozone layer, but it is unclear what fraction of HCl actually reaches the stratosphere. The adsorption of HCl on volcanic ash was therefore studied from -76 to +150 °C to simulate the behavior of HCl in the dilute parts of a volcanic plume. Finely ground synthetic glasses of andesitic, dacitic, and rhyolitic composition as well as a natural obsidian from Vulcano (Italy) served as proxies for fresh natural ash. HCl adsorption is an irreversible process and appears to increase with the total alkali content of the glass. Adsorption kinetics follow a first order law with rate constants of 2.13 ṡ10-6 s-1 to 1.80 ṡ10-4 s-1 in the temperature range investigated. For dacitic composition, the temperature and pressure dependence of adsorption can be described by the equation ln ⁡ c = 1.26 + 0.27 ln ⁡ p - 715.3 / T, where c is the surface concentration of adsorbed HCl in mg/m2, T is temperature in Kelvin, and p is the partial pressure of HCl in mbar. A comparison of this model with a large data set for the composition of volcanic ash suggests that adsorption of HCl from the gas phase at relatively low temperatures can quantitatively account for the majority of the observed Cl concentrations. The model implies that adsorption of HCl on ash increases with temperature, probably because of the increasing number of accessible adsorption sites. This temperature dependence is opposite to that observed for SO2, so that HCl and SO2 are fractionated by the adsorption process and the fractionation factor changes by four orders of magnitude over a temperature range of 250 K. The assumption of equal adsorption of different species is therefore not appropriate for deriving volcanic gas compositions from analyses of adsorbates on ash. However, with the experimental

  13. Adsorption Model for Off-Gas Separation

    Energy Technology Data Exchange (ETDEWEB)

    Veronica J. Rutledge

    2011-03-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  14. Cryogels: morphological, structural and adsorption characterisation.

    Science.gov (United States)

    Gun'ko, Vladimir M; Savina, Irina N; Mikhalovsky, Sergey V

    2013-01-01

    Experimental results on polymer, protein, and composite cryogels and data treatment methods used for morphological, textural, structural, adsorption and diffusion characterisation of the materials are analysed and compared. Treatment of microscopic images with specific software gives quantitative structural information on both native cryogels and freeze-dried materials that is useful to analyse the drying effects on their structure. A combination of cryoporometry, relaxometry, thermoporometry, small angle X-ray scattering (SAXS), equilibrium and kinetic adsorption of low and high-molecular weight compounds, diffusion breakthrough of macromolecules within macroporous cryogel membranes, studying interactions of cells with cryogels provides a consistent and comprehensive picture of textural, structural and adsorption properties of a variety of cryogels. This analysis allows us to establish certain regularities in the cryogel properties related to narrow (diameter 0.4100 μm) with boundary sizes within modified life science pore classification. Particular attention is paid to water bound in cryogels in native superhydrated or freeze-dried states. At least, five states of water - free unbound, weakly bound (changes in the Gibbs free energy-ΔG0.8 kJ/mol), and weakly associated (chemical shift of the proton resonance δ(H)=1-2 ppm) and strongly associated (δ(H)=3-6 ppm) waters can be distinguished in hydrated cryogels using (1)H NMR, DSC, TSDC, TG and other methods. Different software for image treatment or developed to analyse the data obtained with the adsorption, diffusion, SAXS, cryoporometry and thermoporometry methods and based on regularisation algorithms is analysed and used for the quantitative morphological, structural and adsorption characterisation of individual and composite cryogels, including polymers filled with solid nano- or microparticles.

  15. Adsorption Model for Off-Gas Separation

    International Nuclear Information System (INIS)

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed in gPROMS software. Inputs include gas stream constituents, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. It models dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions for a multiple component gas stream. The simulation outputs component concentrations along the column length as a function of time from which the breakthrough data is obtained. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data will be input into the adsorption model to develop a model specific for iodine adsorption on silver mordenite as well as model(s) specific for krypton and xenon adsorption. The model will be validated with experimental breakthrough curves. Another future off-gas modeling goal is to develop a model for the unit operation absorption. The off-gas models will be made available via the server or web for evaluation by customers.

  16. How specific halide adsorption varies hydrophobic interactions.

    Science.gov (United States)

    Stock, Philipp; Müller, Melanie; Utzig, Thomas; Valtiner, Markus

    2016-03-11

    Hydrophobic interactions (HI) are driven by the water structure around hydrophobes in aqueous electrolytes. How water structures at hydrophobic interfaces and how this influences the HI was subject to numerous studies. However, the effect of specific ion adsorption on HI and hydrophobic interfaces remains largely unexplored or controversial. Here, the authors utilized atomic force microscopy force spectroscopy at well-defined nanoscopic hydrophobic interfaces to experimentally address how specific ion adsorption of halide ions as well as NH4 (+), Cs(+), and Na(+) cations alters interaction forces across hydrophobic interfaces. Our data demonstrate that iodide adsorption at hydrophobic interfaces profoundly varies the hydrophobic interaction potential. A long-range and strong hydration repulsion at distances D > 3 nm, is followed by an instability which could be explained by a subsequent rapid ejection of adsorbed iodides from approaching hydrophobic interfaces. In addition, the authors find only a weakly pronounced influence of bromide, and as expected no influence of chloride. Also, all tested cations do not have any significant influence on HI. Complementary, x-ray photoelectron spectroscopy and quartz-crystal-microbalance with dissipation monitoring showed a clear adsorption of large halide ions (Br(-)/I(-)) onto hydrophobic self-assembled monolayers (SAMs). Interestingly, iodide can even lead to a full disintegration of SAMs due to specific and strong interactions of iodide with gold. Our data suggest that hydrophobic surfaces are not intrinsically charged negatively by hydroxide adsorption, as it was generally believed. Hydrophobic surfaces rather interact strongly with negatively charged large halide ions, leading to a surface charging and significant variation of interaction forces.

  17. Adsorption behavior of Cu(II) onto titanate nanofibers prepared by alkali treatment.

    Science.gov (United States)

    Li, Nian; Zhang, Lide; Chen, Yongzhou; Tian, Yue; Wang, Huimin

    2011-05-15

    Novel low-cost adsorbents of titanate nanofibers with formula Na(x)H(2-x)Ti(3)O(7) · nH(2)O have been prepared by alkali treatment for Cu(II) removal from aqueous solutions. The nanofibers have structures in which three edge-shared TiO(6) octahedras join at the corners to form stepped, zigzag Ti(3)O(7)(2-) layers. The sodium cations located between the layers are exchangeable. The results of batch adsorption experiments suggest that the nanofibers with high sodium content can be effective adsorbents for Cu(II) removal. Effects of several important factors such as Na amount in adsorbents, pH, temperature, contact time and initial concentration are systematically studied. Results show that the adsorption is highly pH-dependent and the removal is almost complete (99.8%) for initial concentration under 100mg/l at pH 4. Equilibrium adsorption follows Langmuir isotherms well and the maximum Cu(II) uptake calculated is 167.224 mg/g. The adsorption kinetics can be explained by pseudo-second-order model well and the time needed for equilibrium is 180 min. Thermodynamic study indicates that the adsorption is spontaneous and endothermic. Desorption of Cu(II) from adsorbents using EDTA-2Na solutions exhibits a high efficiency and the adsorbents can be used repeatedly. These results demonstrate that the titanate nanofibers are readily prepared, enabling promising applications for the removal of Cu(II) from aqueous solutions.

  18. Adsorption behavior of Cu(II) onto titanate nanofibers prepared by alkali treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Nian [Key Laboratory of Materials Physics, Anhui Key laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhang, Lide, E-mail: ldzhang@issp.ac.cn [Key Laboratory of Materials Physics, Anhui Key laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Chen, Yongzhou; Tian, Yue; Wang, Huimin [Key Laboratory of Materials Physics, Anhui Key laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2011-05-15

    Novel low-cost adsorbents of titanate nanofibers with formula Na{sub x}H{sub 2-x}Ti{sub 3}O{sub 7}.nH{sub 2}O have been prepared by alkali treatment for Cu(II) removal from aqueous solutions. The nanofibers have structures in which three edge-shared TiO{sub 6} octahedras join at the corners to form stepped, zigzag Ti{sub 3}O{sub 7}{sup 2-} layers. The sodium cations located between the layers are exchangeable. The results of batch adsorption experiments suggest that the nanofibers with high sodium content can be effective adsorbents for Cu(II) removal. Effects of several important factors such as Na amount in adsorbents, pH, temperature, contact time and initial concentration are systematically studied. Results show that the adsorption is highly pH-dependent and the removal is almost complete (99.8%) for initial concentration under 100 mg/l at pH 4. Equilibrium adsorption follows Langmuir isotherms well and the maximum Cu(II) uptake calculated is 167.224 mg/g. The adsorption kinetics can be explained by pseudo-second-order model well and the time needed for equilibrium is 180 min. Thermodynamic study indicates that the adsorption is spontaneous and endothermic. Desorption of Cu(II) from adsorbents using EDTA-2Na solutions exhibits a high efficiency and the adsorbents can be used repeatedly. These results demonstrate that the titanate nanofibers are readily prepared, enabling promising applications for the removal of Cu(II) from aqueous solutions.

  19. Tungsten oxide – fly ash oxide composites in adsorption and photocatalysis

    International Nuclear Information System (INIS)

    Highlights: • A novel fly ash – WO3 composite was synthesized via mild hydrothermal treatment. • Simultaneous dyes and copper adsorption efficiently runs on the composite. • In situ tandem systems (TiO2–WO3) supports the high photocatalytic activity. • The processes kinetics mainly depend on the dye’s structure and flexibility. • Thermodynamics depend on the copper–dye/copper–dye-substrate interactions. - Abstract: A novel composite based on tungsten oxide and fly ash was hydrothermally synthetized to be used as substrate in the advanced treatment of wastewaters with complex load resulted from the textile industry. The proposed treatment consists of one single step process combining photocatalysis and adsorption. The composite’s crystalline structure was investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to analyze the morphology. The adsorption capacity and photocatalytic properties of the material were tested on mono- and multi-pollutants systems containing two dyes (Bemacid Blau – BB and Bemacid Rot – BR) and one heavy metal ion-Cu2+, and the optimized process conditions were identified. The results indicate better removal efficiencies using the novel composite material in the combined adsorption and photocatalysis, as compared to the separated processes. Dyes removal was significantly enhanced in the photocatalytic process by adding hydrogen peroxide and the mechanism was presented and discussed. The pseudo second order kinetics model best fitted the experimental data, both in the adsorption and in the combined processes. The kinetic parameters were calculated and correlated with the properties of the composite substrate

  20. Tungsten oxide – fly ash oxide composites in adsorption and photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Visa, Maria, E-mail: maria.visa@unitbv.ro; Bogatu, Cristina, E-mail: cristina.bogatu@unitbv.ro; Duta, Anca, E-mail: a.duta@unitbv.ro

    2015-05-30

    Highlights: • A novel fly ash – WO{sub 3} composite was synthesized via mild hydrothermal treatment. • Simultaneous dyes and copper adsorption efficiently runs on the composite. • In situ tandem systems (TiO{sub 2}–WO{sub 3}) supports the high photocatalytic activity. • The processes kinetics mainly depend on the dye’s structure and flexibility. • Thermodynamics depend on the copper–dye/copper–dye-substrate interactions. - Abstract: A novel composite based on tungsten oxide and fly ash was hydrothermally synthetized to be used as substrate in the advanced treatment of wastewaters with complex load resulted from the textile industry. The proposed treatment consists of one single step process combining photocatalysis and adsorption. The composite’s crystalline structure was investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to analyze the morphology. The adsorption capacity and photocatalytic properties of the material were tested on mono- and multi-pollutants systems containing two dyes (Bemacid Blau – BB and Bemacid Rot – BR) and one heavy metal ion-Cu{sup 2+}, and the optimized process conditions were identified. The results indicate better removal efficiencies using the novel composite material in the combined adsorption and photocatalysis, as compared to the separated processes. Dyes removal was significantly enhanced in the photocatalytic process by adding hydrogen peroxide and the mechanism was presented and discussed. The pseudo second order kinetics model best fitted the experimental data, both in the adsorption and in the combined processes. The kinetic parameters were calculated and correlated with the properties of the composite substrate.

  1. Synthesis of Fe3O4/Polyacrylonitrile Composite Electrospun Nanofiber Mat for Effective Adsorption of Tetracycline.

    Science.gov (United States)

    Liu, Qing; Zhong, Lu-Bin; Zhao, Quan-Bao; Frear, Craig; Zheng, Yu-Ming

    2015-07-15

    Novel Fe3O4/polyacrylonitrile (PAN) composite nanofibers (NFs) were prepared by a simple two-step process, an electrospinning and solvothermal method. Characterization by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) demonstrated formation of a uniform nanoparticles coating (about 20 nm in thickness) on the PAN nanofiber backbone. The coating was constructed by well-crystallized cubic phase Fe3O4 nanoparticles as examined by X-ray diffraction spectroscopy (XRD). The coating doubled the specific surface area of NFs, from 8.4 to 17.8 m2 g(-1), as confirmed by nitrogen sorption isotherm analysis. To evaluate the feasibility of Fe3O4/PAN composite NFs as a potential adsorbent for antibiotic removal, batch adsorption experiments were conducted using tetracycline (TC) as the model antibiotic molecule. The results showed that Fe3O4/PAN composite NFs were effective in removing TC with no impactful loss of Fe in the pH regime of environmental interest (5-8). The adsorption of TC onto Fe3O4/PAN composite NFs better fitted the pseudo-second-order kinetics model, and the maximum adsorption capacity calculated from Langmuir isotherm model was 257.07 mg g(-1) at pH 6. The composite NFs also exhibited good regenerability over repeated adsorption/desorption cycles. Surface complexation between TC and the composite NFs contributed most to the adsorption as elucidated by X-ray photoelectron spectroscopy (XPS). This highly effective and novel adsorbent can be easily modularized and separated, promising its huge potential in drinking and wastewater treatment for antibiotic removal. PMID:26079116

  2. The mass transfer dynamics of gaseous methyl-iodide adsorption by silver-exchanged sodium mordenite

    International Nuclear Information System (INIS)

    The adsorption of methyl iodide onto hydrogen-reduced silver-exchange mordenite was studied. The removal of organic iodides from off-gas streams is an important step in controlling the release of radioactive iodine to the environment during the treatment of radioactive wastes or the processing of some irradiated materials. Nine well accepted mass transfer models were evaluated for their ability to adequately explain the observed CH3I uptake behavior onto the Ag-Z. Linear and multidimensional regression techniques were utilized in the estimation of the diffusion constants and other model parameters which then permitted the selection of an appropriate mass transfer model. To date, only bulk loading data exist for the adsorption of CH3I onto Ag-Z. Hence this is believed to be the first study to quantify the controlling mass transfer mechanisms of this process. It can be concluded from the analysis of the experimental data obtained by the single-pellet type experiments and for the process conditions used in this study that the overall mass transfer rate associated with the adsorption of CH3I onto Ag-Z is affected by both micropore and macropore diffusion. The macropore diffusion rate was significantly faster than the micropore diffusion, resulting in a two-step adsorption behavior which was adequately modeled by a bimodal pore distribution model. The micropore diffusivity was determined to be on the order of 2 x 10-14 cm2/s. The system was also shown to be isothermal under all conditions of this study. Two other conclusions were also obtained. First, the gas film resistance to mass transfer for the 1/16 and 1/8-in.-diam Ag-Z pellets can be ignored under the conditions used in this study. Finally, it was shown that by decreasing the water vapor content of the feed gas, the chemical reaction rate appeared to become the initial rate-limiting factor for the mass transfer. 75 refs

  3. Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

    Science.gov (United States)

    Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

    2003-03-17

    Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent.

  4. Description of adsorption of hydrophobic organic compounds on sediment using multi-component adsorption model

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A chemical sequential separation procedure for sediment bas been developed for the adsorptive investigation of hydrophobic organic compounds(HOCs) including four fractions: carbonate, hydrous metallic oxide(ferric oxide, manganese oxide and alumina), clay and organic matter. Adsorption isotherms of these hydrophobic solute probes, such as hexachloroethane, lindane and 1,2,4,5-tetrachlorobenzene were measured for model sorbents, model and natural sediment, and the latter of which was pretreated with the simplified sequential separation method. The linear and Langmuir models are applied to correlate the experimental data of humic substance and other model sorbents respectively. Multi-component Adsorptive Model (MCAM) was used to simulate adsorption isotherms of model and natural sediment. The results reveal that( 1 ) the separation efficiencies of carbonate, organic matter, ferric oxide, manganese oxide and alumina are 98. 1 % , 72.5% ,82.6%, 93.5% and 83.3%, respectively; (2) except for removing metallic oxide, the external structure of sediment is not changed greatly after separation; (3) the MCAM correlates the data of adsorption isotherm rather well with the maximal relative deviations of 9.76 % , 6.78 %and 9.53% for hexachloroethane, lindane and 1,2,4,5-tetrachlorobenaze in model sediment, respectively. The MCAM can clearly give expression to the different adsorptive mechanisms for HOCs in organic and inorganic matter, though the experimental data in each component are not very accurate due to the sequential separation efficiency.

  5. Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

    Science.gov (United States)

    Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

    2003-03-17

    Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent. PMID:12628781

  6. Phosphate adsorption on aluminum-coordinated functionalized macroporous–mesoporous silica: Surface structure and adsorption behavior

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Al-coordinated functionalized macroporous–mesoporous silica for phosphate removal. • It had the maximum adsorption capacity of 23.59 mg P/g. • Over 95% of the final adsorption capacity reached in the first 1 min. - Abstract: In this study, Al(III)-coordinated diamino-functionalized macroporous–mesoporous silica was synthesized and characterized by X-ray diffraction, N2 adsorption–desorption, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy. Because of well-defined and interconnecting macroporous–mesoporous networks, the resulting adsorbent (MM-SBA) exhibited a significantly better phosphate adsorption performance and faster removal rate, as compared with the mesoporous adsorbent (M-SBA). Based on the Freundlich and Langmuir models, the phosphate adsorption capacity and the maximum adsorption capacity of MM-SBA were 7.99 mg P/g and 23.59 mg P/g, respectively. In the kinetic study of MM-SBA, over 95% of its final adsorption capacity reached in the first 1 min; whereas that of M-SBA was less than 79%

  7. Phosphate adsorption on aluminum-coordinated functionalized macroporous–mesoporous silica: Surface structure and adsorption behavior

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Weiya [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Department of Materials Science and Engineering, Taizhou University, Linhai 317000 (China); Li, Dan [Environmetal Engineering, School of Engineering and Information Technology, Murdoch University, Murdoch, Western Australia 6150 (Australia); Zhu, Yi; Xu, Kai; Li, Jianqiang [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Han, Boping [Institute of Hydrobiology, Jinan University, Guangzhou 510460 (China); Zhang, Yuanming, E-mail: tzhangym@jnu.edu.cn [Department of Chemistry, Jinan University, Guangzhou 510632 (China)

    2013-12-15

    Graphical abstract: - Highlights: • Al-coordinated functionalized macroporous–mesoporous silica for phosphate removal. • It had the maximum adsorption capacity of 23.59 mg P/g. • Over 95% of the final adsorption capacity reached in the first 1 min. - Abstract: In this study, Al(III)-coordinated diamino-functionalized macroporous–mesoporous silica was synthesized and characterized by X-ray diffraction, N{sub 2} adsorption–desorption, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy. Because of well-defined and interconnecting macroporous–mesoporous networks, the resulting adsorbent (MM-SBA) exhibited a significantly better phosphate adsorption performance and faster removal rate, as compared with the mesoporous adsorbent (M-SBA). Based on the Freundlich and Langmuir models, the phosphate adsorption capacity and the maximum adsorption capacity of MM-SBA were 7.99 mg P/g and 23.59 mg P/g, respectively. In the kinetic study of MM-SBA, over 95% of its final adsorption capacity reached in the first 1 min; whereas that of M-SBA was less than 79%.

  8. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    Science.gov (United States)

    Chakrabarty, Aurab; Bouhali, Othmane; Mousseau, Normand; Becquart, Charlotte S.; El-Mellouhi, Fedwa

    2016-08-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  9. Intensification of adsorption process by using the pyrolytic char from waste tires to remove chromium(Ⅵ) from wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jie; YANG Yong-rong

    2004-01-01

    Pyrolysis has the potential of transforming waste into valuable recyclable products. Pyrolytic char(PC) is one of the most important products from the pyrolysis of used tires. One of the most significant applications for pyrolytic char recovered is used for the removal of Cr(Ⅵ) in the wastewater effluent to control waste by waste. The surface chemistry properties of surface element distribution / concentration and chemical structure were examined for the pyrolytic char and the commercial activated carbon(CAC) respectively. The results showed that surfaces of PC possesses a large amount of ester and hydrocarbon graft, whereas there are mainly carbon functional components of C-OH, C=O and COOH on the surface of CAC. Therefore the surface electronegativity of PC is lower than that of CAC in the water. The repulsive interactions between the surfaces of PC and the negatively charged Cr(Ⅵ) ion are weaker than that of CAC, which results in an intensification of the adsorption process by the utilization of PC. The adsorption isotherms of Cr(Ⅵ) ion on the two kinds of carbons were determined experimentally. The larger adsorption amount on the PC in the case of Cr(Ⅵ) may be attributed mainly to its special surface micro-chemical environment. The mechanism of the removal Cr(Ⅵ) from aqueous solution was assumed to be the integration of adsorption and redox reaction. The adsorption was the rate-controlled step for Cr(Ⅵ) removal. The adsorption of Cr(Ⅵ) has been identified as pseudo-second- order kinetics. The rate constants of adsorption have been evaluated.

  10. Adsorption of Cu(II), Co(II), and Ni(II) ions by modified magnetic chitosan chelating resin

    Energy Technology Data Exchange (ETDEWEB)

    Monier, M., E-mail: monierchem@yahoo.com [Department of Chemistry, Drexel University, Philadelphia, PA (United States); Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Ayad, D.M. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Wei, Y., E-mail: weiyen@drexel.edu [Department of Chemistry, Drexel University, Philadelphia, PA (United States); Sarhan, A.A. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2010-05-15

    Cross-linked magnetic chitosan-isatin Schiff's base resin (CSIS) was prepared for adsorption of metal ions. CSIS obtained was investigated by means of FTIR, {sup 1}H NMR, wide-angle X-ray diffraction (WAXRD), magnetic properties and thermogravimetric analysis (TGA). The adsorption properties of cross-linked magnetic CSIS resin toward Cu{sup 2+}, Co{sup 2+} and Ni{sup 2+} ions were evaluated. Various factors affecting the uptake behavior such as contact time, temperature, pH and initial concentration of the metal ions were investigated. The kinetic parameters were evaluated utilizing the pseudo-first-order and pseudo-second-order. The equilibrium data were analyzed using the Langmuir, Freundlich, and Tempkin isotherm models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, evidencing chemical sorption as the rate-limiting step of adsorption mechanism and not involving a mass transfer in solution. The best interpretation for the equilibrium data was given by Langmuir isotherm, and the maximum adsorption capacities were 103.16, 53.51, and 40.15 mg/g for Cu{sup 2+}, Co{sup 2+} and Ni{sup 2+} ions, respectively. Cross-linked magnetic CSIS displayed higher adsorption capacity for Cu{sup 2+} in all pH ranges studied. The adsorption capacity of the metal ions decreased with increasing temperature. The metal ion-loaded cross-linked magnetic CSIS were regenerated with an efficiency of greater than 88% using 0.01-0.1 M ethylendiamine tetraacetic acid (EDTA).

  11. Using mathematical models to understand the effect of nanoscale roughness on protein adsorption for improving medical devices

    Directory of Open Access Journals (Sweden)

    Ercan B

    2013-09-01

    Full Text Available Batur Ercan,1 Dongwoo Khang,2 Joseph Carpenter,3 Thomas J Webster1 1Department of Chemical Engineering, Northeastern University, Boston, MA, USA; 2School of Materials Science and Engineering and Center for PRC and RIGET, Gyeongsang National University, Jinju, South Korea; 3School of Medicine, Stanford University, Stanford, CA, USA Abstract: Surface roughness and energy significantly influence protein adsorption on to biomaterials, which, in turn, controls select cellular adhesion to determine the success and longevity of an implant. To understand these relationships at a fundamental level, a model was originally proposed by Khang et al to correlate nanoscale surface properties (specifically, nanoscale roughness and energy to protein adsorption, which explained the greater cellular responses on nanostructured surfaces commonly reported in the literature today. To test this model for different surfaces from what was previously used to develop that model, in this study we synthesized highly ordered poly(lactic-co-glycolic acid surfaces of identical chemistry but altered nanoscale surface roughness and energy using poly(dimethylsiloxane molds of polystyrene beads. Fibronectin and collagen type IV adsorption studies showed a linear adsorption behavior as the surface nanoroughness increased. This supported the general trends observed by Khang et al. However, when fitting such data to the mathematical model established by Khang et al, a strong correlation did not result. Thus, this study demonstrated that the equation proposed by Khang et al to predict protein adsorption should be modified to accommodate for additional nanoscale surface property contributions (ie, surface charge to make the model more accurate. In summary, results from this study provided an important step in developing future mathematical models that can correlate surface properties (such as nanoscale roughness and surface energy to initial protein adsorption events important to

  12. The over-step coalescence of carbon atoms on copper surface in the CVD growth of graphene: density functional calculations

    Directory of Open Access Journals (Sweden)

    Yingfeng Li

    2013-05-01

    Full Text Available The ways in which carbon atoms coalesce over the steps on copper (111 surface are ascertained by density functional theory (DFT calculations in the context of chemical vapor deposition (CVD growth of graphene. Two strategies, (1 by putting carbon atoms on and under the steps separately and (2 by importing additional carbon atoms between the ones separated by the steps, have been attempted to investigate if an over-step coalescence of carbon atoms could take place. Based on analyses about the optimized configurations and adsorption energies of carbon atoms nearby the steps, as well as the energy evolution curve of the system throughout the geometry optimizations process, we determined the main way in which graphene grows over the steps continuously: the carbon atoms, adsorbed additionally on the locations between the already existing ones which are separated by the steps, link them (these carbon atoms separated by the steps together. The direct over-step coalescence of the carbon atoms separated by the steps is very difficult, although the energy barrier preventing their coalescence can be weakened by importing carbon atoms on and under the steps gradually. Our results imply potential applications in directing the fabrication of graphene with particular structure by controlling the surface topography of copper substrate.

  13. Selective recovery of Pd(II) from extremely acidic solution using ion-imprinted chitosan fiber: Adsorption performance and mechanisms.

    Science.gov (United States)

    Lin, Shuo; Wei, Wei; Wu, Xiaohui; Zhou, Tao; Mao, Juan; Yun, Yeoung-Sang

    2015-12-15

    A novel, selective and acid-resisting chitosan fiber adsorbent was prepared by the ion-imprinting technique using Pd(II) and epichlorohydrin as the template and two-step crosslinking agent, respectively. The resulting ion-imprinted chitosan fibers (IIF) were used to selectively adsorb Pd(II) under extremely acidic synthetic metal solutions. The adsorption and selectivity performances of IIF including kinetics, isotherms, pH effects, and regeneration were investigated. Pd(II) rapidly adsorbed on the IIF within 100 min, achieving the adsorption equilibrium. The isotherm results showed that the maximum Pd(II) uptake on the IIF was maintained as 324.6-326.4 mg g(-1) in solutions containing single and multiple metals, whereas the Pd(II) uptake on non-imprinted fibers (NIF) decreased from 313.7 to 235.3 mg g(-1) in solution containing multiple metals. Higher selectivity coefficients values were obtained from the adsorption on the IIF, indicating a better Pd(II) selectivity. The amine group, supposedly the predominant adsorption site for Pd(II), was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The pH value played a significant role on the mechanism of the selective adsorption in the extremely acidic conditions. Furthermore, the stabilized performance for three cycles of sorption/desorption shows a potential for further large-scale applications. PMID:26073516

  14. Enhanced adsorptive removal of p-nitrophenol from water by aluminum metal–organic framework/reduced graphene oxide composite

    Science.gov (United States)

    Wu, Zhibin; Yuan, Xingzhong; Zhong, Hua; Wang, Hou; Zeng, Guangming; Chen, Xiaohong; Wang, Hui; Zhang, Lei; Shao, Jianguang

    2016-05-01

    In this study, the composite of aluminum metal–organic framework MIL-68(Al) and reduced graphene oxide (MA/RG) was synthesized via a one–step solvothermal method, and their performances for p–nitrophenol (PNP) adsorption from aqueous solution were systematically investigated. The introduction of reduced graphene oxide (RG) into MIL-68(Al) (MA) significantly changes the morphologies of the MA and increases the surface area. The MA/RG-15% prepared at RG-to-MA mass ratio of 15% shows a PNP uptake rate 64% and 123% higher than MIL-68(Al) and reduced graphene oxide (RG), respectively. The hydrogen bond and π – π dispersion were considered to be the major driving force for the spontaneous and endothermic adsorption process for PNP removal. The adsorption kinetics, which was controlled by film–diffusion and intra–particle diffusion, was greatly influenced by solution pH, ionic strength, temperature and initial PNP concentration. The adsorption kinetics and isotherms can be well delineated using pseudo–second–order and Langmuir equations, respectively. The presence of phenol or isomeric nitrophenols in the solution had minimal influence on PNP adsorption by reusable MA/RG composite.

  15. Co-Adsorption of CO in NO-CO Reaction on a Metal Catalytic Surface Studied by Computer Simulation

    Institute of Scientific and Technical Information of China (English)

    Waqar Ahmad

    2009-01-01

    The effect of co-adsorption of CO molecules in the NO-CO reaction on a metal catalytic surface like Pt(001) is studied by applying the Langmuir-Hinshelwood mechanism using the Monte Carlo simulations.The system is investigated by two approaches of NO adsorption;dissociatively at two empty surface sites and molecularly at a single vacant site. The elementary steps are the same as those in the conventional Ziff-Gulari-Barshad model.With the additional reaction step of co-adsorption,the sustained production of CO2 is obtained,which has never been seen on a square lattice without introducing additional parameters.The most interesting result is the elimination of continuous second order phase transition,i.e.the production of CO2 starts as soon as the partial pressure of CO departs from zero,which is in accordance with the experimental observations,The effect of co-adsorption probability on the phase diagrams has also been studied.

  16. A novel method of synthesizing cyclodextrin grafted multiwall carbon nanotubes/iron oxides and its adsorption of organic pollutant

    International Nuclear Information System (INIS)

    Highlights: • A cost-effective and one-step method for grafting cyclodextrin onto magnetic material. • Relatively good separation and regeneration properties as adsorbent. • The adsorption capacities are comparable with other adsorbents reported previously. - Abstract: A novel methodology for the synthesis of the multiwalled carbon nanotubes/iron oxides modified by β-cyclodextrin (denoted as MWCNTs/iron oxides/β-CD) was proposed using 1,6-diisocyanatohexane as cross-linker in N,N-dimethyl formamide, which avoided complex steps in the link of β-cyclodextrin and MWCNTs/iron oxides via conventional synthetic methods. The characteristic results of Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and thermogravimetric analysis (TGA) showed that β-CD was grafted onto the MWCNTs/iron oxides successfully. In addition, vibrating sample magnetometer (VSM) and magnetic separation experiment suggested that the prepared composite exhibited preferable magnetic property and good dispersion property in aqueous solution. The effects of contact time, initial adsorbent content, solution pH and temperature on the adsorption of p-nitrophenol (PNP) were studied systematically. The adsorption kinetics and equilibrium isotherms data fitted well with pseudo-second-order kinetic equation and Langmuir isotherm model, respectively. Furthermore, the adsorption-desorption experiment of PNP demonstrated that MWCNTs/iron oxides/β-CD is a cost-effective material with high regeneration efficiency

  17. A novel method of synthesizing cyclodextrin grafted multiwall carbon nanotubes/iron oxides and its adsorption of organic pollutant

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Jiang, Xinyu [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Chen, Xiaoqing, E-mail: xqchen@csu.edu.cn [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Collaborative Innovation Center of Resource-conserving and Environment-friendly Society and Ecological Civilization (China)

    2014-11-30

    Highlights: • A cost-effective and one-step method for grafting cyclodextrin onto magnetic material. • Relatively good separation and regeneration properties as adsorbent. • The adsorption capacities are comparable with other adsorbents reported previously. - Abstract: A novel methodology for the synthesis of the multiwalled carbon nanotubes/iron oxides modified by β-cyclodextrin (denoted as MWCNTs/iron oxides/β-CD) was proposed using 1,6-diisocyanatohexane as cross-linker in N,N-dimethyl formamide, which avoided complex steps in the link of β-cyclodextrin and MWCNTs/iron oxides via conventional synthetic methods. The characteristic results of Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and thermogravimetric analysis (TGA) showed that β-CD was grafted onto the MWCNTs/iron oxides successfully. In addition, vibrating sample magnetometer (VSM) and magnetic separation experiment suggested that the prepared composite exhibited preferable magnetic property and good dispersion property in aqueous solution. The effects of contact time, initial adsorbent content, solution pH and temperature on the adsorption of p-nitrophenol (PNP) were studied systematically. The adsorption kinetics and equilibrium isotherms data fitted well with pseudo-second-order kinetic equation and Langmuir isotherm model, respectively. Furthermore, the adsorption-desorption experiment of PNP demonstrated that MWCNTs/iron oxides/β-CD is a cost-effective material with high regeneration efficiency.

  18. Adsorption study of anionic reactive dye from aqueous solution to Mg-Fe-CO{sub 3} layered double hydroxide (LDH)

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, I.M., E-mail: ismawy@yahoo.ca [Hot Labs Centre, Atomic Energy Authority, P. Code 13759, Cairo (Egypt); Gasser, M.S. [Hot Labs Centre, Atomic Energy Authority, P. Code 13759, Cairo (Egypt)

    2012-10-15

    Graphical abstract: Second order kinetic model for adsorption of congo red onto Mg-Fe-LDH. Highlights: Black-Right-Pointing-Pointer Mg-Fe-CO{sub 3}-LDH was utilized as an adsorbent. Black-Right-Pointing-Pointer It was used for the removal of congo red (CR), an anionic dye from aqueous solution. Black-Right-Pointing-Pointer The adsorption of (CR) is endothermic. Black-Right-Pointing-Pointer The adsorption equilibrium was well described by the Langmuir isotherm model. Black-Right-Pointing-Pointer Adsorption kinetics of (CR) was found to conform to pseudo-second order model. - Abstract: Mg-Fe-Cl Layered double hydroxides (LDHs) have been prepared using a method involving separate nucleation and aging steps with Mg/Fe = 3. The interlayer anions readily replaced by carbonate are characterized by X-ray diffraction (XRD) and FTIR. The effects of different parameters, such as pH, contact time, concentration of dye and temperature on the capacity and adsorption mechanism of Mg-Fe-CO{sub 3}-LDH in removing an anionic dye (congo red, CR) from aqueous solution were separately investigated. The results show that Mg-Fe-CO{sub 3}-LDH is particularly efficient in removing CR and the dye removal increases with decreasing pH. The adsorption of CR on Mg-Fe-CO{sub 3}-LDH reached equilibrium after 15 min where 100 mg/L CR was removed. The equilibrium isotherm indicates that the adsorption of CR onto Mg-Fe-CO{sub 3}-LDH fits to Langmuir and Freundlich equation as well. The adsorption data obtained from the Langmuir model gave good values of the determination coefficient and the saturated adsorption capacity of Mg-Fe-CO{sub 3}-LDH for CR was found to be 104.6 mg/g. The regeneration study indicates that the prepared LDH could be used for several cycles. The thermodynamic parameters have been calculated, and the adsorption process was found to be spontaneous, endothermic in nature and follows a pseudo-second-order kinetic model.

  19. Staircase Structure of Shapiro Steps

    Science.gov (United States)

    Shukrinov, Yu. M.; Rahmonov, I. R.; Nashaat, M.

    2015-12-01

    We investigate IV-characteristics of coupled Josephson junctions which model the intrinsic Josephson junctions in high temperature superconductors under external electromagnetic radiation. A staircase structure of Shapiro steps is found in the branching region. Its origin is related to the coupling between junctions and their switching from rotating to oscillating states. This conclusion is tested by detailed analysis of the IV-characteristics as for total stack and for each junction in the stack. IV-curves of junctions in the stack are compared with the average of time derivative of phase difference. Experimental observation of this staircase structure would give us a proof of coupling between junctions and a way for precise measurement of its value. Such investigations would be also useful for a diagnostic of Josephson junctions in the stack.

  20. Moral transhumanism: the next step.

    Science.gov (United States)

    Tennison, Michael N

    2012-08-01

    Although transhumanism offers hope for the transcendence of human biological limitations, it generates many intrinsic and consequential ethical concerns. The latter include issues such as the exacerbation of social inequalities and the exponentially increasing technological capacity to cause harm. To mitigate these risks, many thinkers have initiated investigations into the possibility of moral enhancement that could limit the power disparities facilitated by biotechnological enhancement. The arguments often focus on whether moral enhancement is morally permissible, or even obligatory, and remain largely in the realm of the hypothetical. This paper proposes that psilocybin may represent a viable, practical option for moral enhancement and that its further research in the context of moral psychology could comprise the next step in the development of moral transhumanism.

  1. Adsorption dynamics and equilibrium studies of Zn (II) onto chitosan

    Indian Academy of Sciences (India)

    G Karthikeyan; K Anbalagan; N Muthulakshmi Andal

    2004-03-01

    Batch equilibration studies are conducted to determine the nature of adsorption of zinc (II) over chitosan. The factors affecting the adsorption process like particle size, contact time, dosage, pH, effects of chloride and nitrate are identified. The influence of temperature and co-ions on the adsorption process is verified. The fraction of adsorption, and the intraparticle diffusion rate constant, are calculated at different environments and the results are discussed. The nature of adsorption of the zinc (II) - chitosan system is explained using Freundlich, Langmuir isotherms and thermodynamic parameters.

  2. Protein adsorption on materials surfaces with nano-topography

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Protein adsorption behavior on the surfaces of biomedical materials is highly related to the biocompatibility of the materials. In the past, numerous research reports were mainly focused on the effect of chemical components of a material's surface on protein adsorption. The effect of surface topography on protein adsorption, the topic of this review, has recently receuvedkeen interest. The influence of surface nano-topographic factors, including roughness, curvature and geometry, on protein adsorption as well as the protein adsorption behavior, such as the amount of protein adsorbed, the activity and morphology of adsorbed protein, is introduced.

  3. Predicting mixed-gas adsorption equilibria on activated carbon for precombustion CO2 capture.

    Science.gov (United States)

    García, S; Pis, J J; Rubiera, F; Pevida, C

    2013-05-21

    We present experimentally measured adsorption isotherms of CO2, H2, and N2 on a phenol-formaldehyde resin-based activated carbon, which had been previously synthesized for the separation of CO2 in a precombustion capture process. The single component adsorption isotherms were measured in a magnetic suspension balance at three different temperatures (298, 318, and 338 K) and over a large range of pressures (from 0 to 3000-4000 kPa). These values cover the temperature and pressure conditions likely to be found in a precombustion capture scenario, where CO2 needs to be separated from a CO2/H2/N2 gas stream at high pressure (~1000-1500 kPa) and with a high CO2 concentration (~20-40 vol %). Data on the pure component isotherms were correlated using the Langmuir, Sips, and dual-site Langmuir (DSL) models, i.e., a two-, three-, and four-parameter model, respectively. By using the pure component isotherm fitting parameters, adsorption equilibrium was then predicted for multicomponent gas mixtures by the extended models. The DSL model was formulated considering the energetic site-matching concept, recently addressed in the literature. Experimental gas-mixture adsorption equilibrium data were calculated from breakthrough experiments conducted in a lab-scale fixed-bed reactor and compared with the predictions from the models. Breakthrough experiments were carried out at a temperature of 318 K and five different pressures (300, 500, 1000, 1500, and 2000 kPa) where two different CO2/H2/N2 gas mixtures were used as the feed gas in the adsorption step. The DSL model was found to be the one that most accurately predicted the CO2 adsorption equilibrium in the multicomponent mixture. The results presented in this work highlight the importance of performing experimental measurements of mixture adsorption equilibria, as they are of utmost importance to discriminate between models and to correctly select the one that most closely reflects the actual process.

  4. A Step by Step Protocol for Subretinal Surgery in Rabbits.

    Science.gov (United States)

    Al-Nawaiseh, Sami; Thieltges, Fabian; Liu, Zengping; Strack, Claudine; Brinken, Ralf; Braun, Norbert; Wolschendorf, Marc; Maminishkis, Arvydas; Eter, Nicole; Stanzel, Boris V

    2016-01-01

    Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in adults in industrially developed countries. RPE transplantation appears to be a promising therapy, as it may replace dysfunctional RPE, restore its function, and thereby vision. Here we describe a method for transplanting a cultured RPE monolayer on a scaffold into the subretinal space (SRS) of rabbits. After vitrectomy xenotransplants were delivered into the SRS using a custom made shooter consisting of a 20-gauge metallic nozzle with a polytetrafluoroethylene (PTFE) coated plunger. The current technique evolved in over 150 rabbit surgeries over 6 years. Post-operative follow-up can be obtained using non-invasive and repetitive in vivo imaging such as spectral domain optical coherence tomography (SD-OCT) followed by perfusion-fixed histology. The method has well-defined steps for easy learning and high success rate. Rabbits are considered a large eye animal model useful in preclinical studies for clinical translation. In this context rabbits are a cost-efficient and perhaps convenient alternative to other large eye animal models. PMID:27684952

  5. Growth of 2D sheets of a MOF on graphene surfaces to yield composites with novel gas adsorption characteristics.

    Science.gov (United States)

    Kumar, Ram; Jayaramulu, Kolleboyina; Maji, Tapas Kumar; Rao, C N R

    2014-05-28

    Homogeneous graphene-MOF composites based on a 2D pillared-bilayer MOF (Cd-PBM), {[Cd4(azpy)2(pyrdc)4(H2O)2]·9H2O}n (azpy = 4,4'-azopyridine, pyrdc = pyridine-2,3-dicarboxylate), have been synthesized, using both graphene oxide (GO) and benzoic acid functionalized graphene (BFG). The composites GO@Cd-PBM and BFG@Cd-PBM demonstrate growth of the 2D nano-sheets of MOF on the graphene surface. While the pristine MOF, Cd-PBM shows selective CO2 uptake with a single-step type-I adsorption profile, the composites show stepwise CO2 uptake with a large hysteresis. With H2O and MeOH, on the other hand, the composites show a single-step adsorption unlike the parent MOF.

  6. Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

    International Nuclear Information System (INIS)

    The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling

  7. Influences of Soluble Salts on Adsorption Properties of Polycarboxylate Superplasticizers

    Institute of Scientific and Technical Information of China (English)

    WANG Dongmin; CHENG Peifu; XIONG Weifeng; SONG Taowen; WU Zengli

    2012-01-01

    Polycarboxylate (PC) superplasticizers with different chemical structures were synthesized through free radical co-polymerization reaction.A total organic carbon analyzer was used to investigate adsorption behaviors of PCs,and to evaluate influences of soluble salts on absorption properties of PCs.It is found that adsorption ratios of PCs on cement particles decrease greatly with the addition of Na2SO4; the adsorption ratio of ethers PC with Hydroxyethyl methacrylate (HEMA) group first increases then decreases with the addition of NaCl; the adsorption ratio of esters PC with short side chains first decreases then increases,while the adsorption ratio of ethers PC with HEMA group decreases with the addition of CaCl2; the adsorption ratio of esters PC with short side chains decreases with the addition of Ca(NO3)2; AlCl3 causes the decrease of the adsorption ratio of ethers PC with HEMA group.

  8. CrⅥ adsorption on four typical soil colloids: equilibrium and kinetics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    It is observed that the adsorption of chromium are greater on kaolinite minerals, red soil (R) and laterite (L) colloids than that on montmorillonite, indicotic black (IB) and yellow brown (YB) soil colloids. The adsorption process of CrⅥ on these media can be further described by Langmuir or Freundlich equation quite well. The adsorption reaction of CrⅥ is fast, and the adsorption equilibrium can be reached within the first two hours in moderate temperature. The adsorption quantity of CrⅥ to kaolinite mineral increased with the increasing pH in the range of 2.0 to 7.0, then decreased at higher pH. But it showed some consistence among the four soil colloids. The lower the pH, the stronger the adsorption. The possible mechanisms are further discussed here. Meanwhile the influence of temperature on CrⅥ adsorption on different soil colloid and clay minerals are also investigated.

  9. Hydrogen adsorption on bimetallic PdAu(111) surface alloys

    DEFF Research Database (Denmark)

    Takehiro, Naoki; Liu, Ping; Bergbreiter, Andreas;

    2014-01-01

    The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining...... the structural information obtained by high resolution scanning tunneling microscopy (STM), in particular on the abundance of specific adsorption ensembles at different Pd surface concentrations, with information on the adsorption properties derived from temperature programmed desorption (TPD) spectroscopy...... and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight...

  10. Adsorption behavior of 239Pu by Gaomiaozi bentonite

    International Nuclear Information System (INIS)

    Adsorption behavior of 239Pu by Gaomiaozi bentonite as a function of the factors of aqueous phase pH value, 239Pu initial concentration and ionic species is studied by static adsorption experiments in this paper. The following results are obtained. Adsorption equilibrium time of 239Pu by Gaomiaozi bentonite samples is about 24 h, and the adsorption distribution ratio Kd value of 239Pu increases with the pH value, but decreases with increasing initial concentration of 239Pu. And adsorption of 239Pu by bentonite samples with different ionic species show that anions affect the most on adsorption of bentonite is CO32-, followed by HCO3- and SO42-, whereas Cl- and NO3- hardly have any influence on the adsorption of bentonite. (authors)

  11. Adsorption of Congo Red onto Lignocellulose/Montmorillonite Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yahong; XUE Zhenhua; WANG Ximing; WANG Li; WANG Aiqin

    2012-01-01

    Lignocellulose/montmorillonite (LNC/MMT) nanocomposites were prepared and characterized by FTIR and XRD.The adsorption of congo red (CR) on LNC/MMT nanocomposite was studied in detail.The effects of contact temperature,pH value of the dye solutions,contact time and concentration of dye solutions on the adsorption capacities of lignocellulose (LNC),montmorillonite (MMT) and the nanocomposite were investigated.The adsorption kinetics and isotherms and adsorption thermodynamics of the nanocomposite for CR were also studied.The results show that the adsorption capacity of LNC/MMT nanocomosite is higher than that of LNC and MMT.All the adsorption processes fit very well with the pseudo-second-order and the Langmuir equation.From thermodynamic studies,it is seen that the adsorption is spontaneous and endothermic.

  12. Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers

    Institute of Scientific and Technical Information of China (English)

    SUN Yue; LI Xiao-tao; XU Chao; CHEN Jin-long; LI Ai-min; ZHANG Quan-xing

    2005-01-01

    Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1,AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition,thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.

  13. Adsorption of Anionic Dyes onto Chitosan-modified Diatomite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ge-shan; XUE Hong-hai; TANG Xiao-jian; PENG Fei; KANG Chun-li

    2011-01-01

    The purpose of this work is to study the possibility of anionic dyes Reactive Red M-8B(RR)and Direct Green B(DG)adsorbed on chitosan-modified diatomite.The characteristics of adsorbent,adsorption isotherms and the influence of adsorption time,temperature and pH were researched in this work.The results show that the modified diatomite had a much better adsorption capability than the natural diatomite.The adsorption capacities of chitosan-modified diatomite for RR and DG were 94.46 and 137.0 mg/g,respectively.Both adsorption time and adsorption temperature provided a positive effect on the dye adsorption.Within the experimental pH range,the adsorbance was enhanced at lower pH but reduced sharply at high pH.On the basis of the experimental results and discussion,electrostatic attraction is considered as the main mechanism of this chemisorption.

  14. Determination of Differential Enthalpy and Isotherm by Adsorption Calorimetry

    Directory of Open Access Journals (Sweden)

    V. Garcia-Cuello

    2008-01-01

    Full Text Available An adsorption microcalorimeter for the simultaneous determination of the differential heat of adsorption and the adsorption isotherm for gas-solid systems are designed, built, and tested. For this purpose, a Calvet heat-conducting microcalorimeter is developed and is connected to a gas volumetric unit built in stainless steel to record adsorption isotherms. The microcalorimeter is electrically calibrated to establish its sensitivity and reproducibility, obtaining K=154.34±0.23 WV−1. The adsorption microcalorimeter is used to obtain adsorption isotherms and the corresponding differential heats for the adsorption of CO2 on a reference solid, such as a NaZSM-5 type zeolite. Results for the behavior of this system are compared with those obtained with commercial equipment and with other studies in the literature.

  15. Exact matrix treatment of an osmotic ensemble model of adsorption and pressure induced structural transitions in metal organic frameworks.

    Science.gov (United States)

    Dunne, Lawrence J; Manos, George

    2016-03-14

    Here we present an exactly treated quasi-one dimensional statistical mechanical osmotic ensemble model of pressure and adsorption induced breathing structural transformations of metal-organic frameworks (MOFs). The treatment uses a transfer matrix method. The model successfully reproduces the gas and pressure induced structural changes which are observed experimentally in MOFs. The model treatment presented here is a significant step towards analytical statistical mechanical treatments of flexible metal-organic frameworks.

  16. One-step synthesis of magnetite core/zirconia shell nanocomposite for high efficiency removal of phosphate from water

    Science.gov (United States)

    Wang, Zhe; Xing, Mingchao; Fang, Wenkan; Wu, Deyi

    2016-03-01

    A self-assembled magnetite core/zirconia shell (Fe3O4@ZrO2) nanoparticle material was fabricated by the one-step co-precipitation method to capture phosphate from water. Fe3O4@ZrO2 with different Fe/Zr molar ratios were obtained and characterized by XRD, TEM, BET surface area and magnetization. It was shown that, with the decreasing of Fe/Zr molar ratio, magnetization decreased whereas surface area and adsorption capacity of phosphate increased. Fe3O4@ZrO2 with the ratio of higher than 4:1 had satisfactory magnetization property (>23.65 emu/g), enabling rapid magnetic separation from water and recycle of the spent adsorbent. The Langmuir adsorption capacity of Fe3O4@ZrO2 reached 27.93-69.44 mg/g, and the adsorption was fast (90% of phosphate removal within 20 min). The adsorption decreases with increasing pH, and higher ionic strength caused slight increase in adsorption at pH > about 5.5. The presence of chloride, nitrate and sulfate anions did not bring about significant changes in adsorption. As a result, Fe3O4@ZrO2 performed well to remove phosphate from real wastewater. These results were interpreted by the ligand exchange mechanism, i.e., the direct coordination of phosphate onto zirconium by replacement of hydroxyl groups. Results suggested that phosphate reacted mainly with surface hydroxyl groups but diffusion into interior of zirconia phase also contributed to adsorption. The adsorbed phosphate could be desorbed with a NaOH treatment and the regenerated Fe3O4@ZrO2 could be repeatedly used.

  17. The Use Of New Adsorption Technology

    International Nuclear Information System (INIS)

    Adsorption is widely used in Gas Dehydration. Recently, new technology has been applied by using a new type of silica gel adsorbent for both gas dehydration and hydrocarbon dew pointing. A study to evaluate the different methods of hydrocarbon dew pointing was performed by Enppi and proved that the use of adsorption process with a new type of silica gel has significant cost benefits over the life of field. In Egypt, this new technology has been used in the Rosetta gas plant, which was designed for 302 MMSCFD (275 + 10%). The plant has been operational for about 4 years and experience demonstrated that the new type of silica gel has high performance, excellent reliability and low operating cost. Following these good results, the plant has been tested up to 380 MMSCFD and again the adsorbent proved its high performance and efficiency

  18. Adsorption of octadecyltrichlorosilane on mesoporous SBA-15

    International Nuclear Information System (INIS)

    Adsorption of octadecyltrichlorosilane (OTS) on mesoporous SBA-15 has been studied by using Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analysis (TGA) techniques. BET surface area analysis shows decrease of surface area from 930 to 416 m2/g after OTS adsorption. SEM pictures show close attachment of SBA-15 particles. EDAX measurements show increase of carbon weight percentage and decrease of oxygen and silicon weight percentage. XPS results closely support EDAX analysis. FTIR spectra shows presence of methyl (-CH3) and methylene (-CH2) bands and oriented OTS monolayer on SBA-15. Thermo-gravimetric analysis shows that the OTS adsorbed on SBA-15 are stable up to a temperature of 230 deg. C and that the OTS monolayers decompose between 230 and 400 deg. C

  19. Adsorption of octadecyltrichlorosilane on mesoporous SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Mirji, S.A. [Physical Chemistry Division, National Chemical Laboratory, Pune 411008 (India)]. E-mail: mirji@dalton.ncl.res.in; Halligudi, S.B. [Inorganic and Catalysis Division, National Chemical Laboratory, Pune 411008 (India); Sawant, Dhanashri P. [Inorganic and Catalysis Division, National Chemical Laboratory, Pune 411008 (India); Jacob, Nalini E. [Inorganic and Catalysis Division, National Chemical Laboratory, Pune 411008 (India); Patil, K.R. [Center for Material Characterization, National Chemical Laboratory, Pune 411008 (India); Gaikwad, A.B. [Center for Material Characterization, National Chemical Laboratory, Pune 411008 (India); Pradhan, S.D. [Center for Material Characterization, National Chemical Laboratory, Pune 411008 (India)

    2006-04-15

    Adsorption of octadecyltrichlorosilane (OTS) on mesoporous SBA-15 has been studied by using Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analysis (TGA) techniques. BET surface area analysis shows decrease of surface area from 930 to 416 m{sup 2}/g after OTS adsorption. SEM pictures show close attachment of SBA-15 particles. EDAX measurements show increase of carbon weight percentage and decrease of oxygen and silicon weight percentage. XPS results closely support EDAX analysis. FTIR spectra shows presence of methyl (-CH{sub 3}) and methylene (-CH{sub 2}) bands and oriented OTS monolayer on SBA-15. Thermo-gravimetric analysis shows that the OTS adsorbed on SBA-15 are stable up to a temperature of 230 deg. C and that the OTS monolayers decompose between 230 and 400 deg. C.

  20. Adsorption of maleic anhydride on Pt(111)

    Science.gov (United States)

    Sinha, Godhuli; Heikkinen, Olli; Vestberg, Matias; Mether, Lotta; Nordlund, Kai; Lahtinen, Jouko

    2014-02-01

    The surface chemistry of maleic anhydride (MA) has been studied on Pt(111) with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. Adsorption of MA takes place at 170 K forming multilayers. We have studied the behavior of distinct carbon and oxygen species of MA depending on the surface temperature. MA-TPD indicates three main desorption temperatures; at 240 K, approximately 60% of total MA on the surface shows molecular desorption. At high temperatures (360 and 550 K) MA shows dissociative decomposition with production of C2H2, CO and CO2 fragments. A plausible decomposition pathway of MA on the Pt(111) surface is discussed. DFT calculations provide details of the adsorption geometry.