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Nadezhda L. Filippova - One of the best experts on this subject based on the ideXlab platform.
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Adsorption Kinetics of Polyelectrolytes on Planar Surfaces under Flow Conditions.
Journal of Colloid and Interface Science, 1999Co-Authors: Nadezhda L. FilippovaAbstract:The focus of our work has been to develop a theory of Adsorption Kinetics for polyelectrolytes in a flow cell onto planar surfaces in the framework of the two-dimensional model and to study Adsorption processes of polyelectrolytes on a planar surface by ellipsometry. We have studied the Adsorption Kinetics of water-soluble cationic poly(vinylamine) hydrochloride homopolymer from aqueous solution onto both silicon wafers and polystyrene films by ellipsometry. Equations were derived to calculate (a) the equilibrium Adsorption, (b) the thickness of the adsorbed layer, (c) the activation energy of Adsorption for water-soluble polyelectrolytes, (d) the rate constant for the water-soluble polyelectrolytes, (e) the effective coefficients of diffusion in the adsorbed layer, and (f) the time needed to attain the equilibrium state for the Adsorption of the water-soluble polyelectrolytes in a flow cell.
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Dynamic Surface Tension and Adsorption Kinetics from Micellar Solutions on Planar Surfaces
Journal of Colloid and Interface Science, 1997Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A qualitative theory of the dynamic surface tension and Adsorption Kinetics from micellar surfactant solutions on a planar surface is developed for the kinetic–diffusive-controlled Adsorption process obeying any Adsorption Kinetics on a planar surface and any micellization–demicellization Kinetics in the bulk. The time-dependent Adsorption and dynamic surface tension is obtained in an analytical form for short and long times. It is shown that the Adsorption process and dynamic surface tension over a wide range of surfactant (monomer) concentrations is governed by: (I) the Adsorption Kinetics of monomers and micelles for short times (0 ≤t ≤ tcr1), (II) the Adsorption Kinetics of monomers and micelles on a planar surface and the micellization–demicellization Kinetics in the bulk, and the diffusion of monomers and micelles for intermediate times (tcr1≤ t ≤ tcr2), and (III) the diffusion of monomers and micelles for long times (t ≥ tcr2). Formulas were derived to estimate the relaxation timestcr1,tcr2, and the parameters characterizing the Adsorption process over a wide range of times. The existence of the (I), (II), and (III) regimes are justified by using the experimental data for the dynamic surface tension of a micellar Brij 58 solution.
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Adsorption Kinetics of Polyelectrolytes on Planar Surfaces in Flow Cell
Journal of Colloid and Interface Science, 1997Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A quantitative theory of kinetic-diffusive-convective Adsorption in a flow cell for polyelectrolyte and mixtures of ions in solutions onto planar surfaces in the framework of the Nernst–Planck approach has been developed by using the new approaches: (a) The effect of the convective transport is estimated in the analytical form. The boundary condition for the rate of Adsorption at the interface (y= 0) is derived for the kinetic-diffusive-convective-controlled Adsorption in a flow cell, taking into account both the normal and the axial fluxes in the flow cell. (b) The total electrical potential in the double layer, ϕ(x,y,t), does not equal the electrical potential, ϕρ(x,y,t), due to the total electrical charge, ρ(x,y,t), in the double layer. It is shown that the total electrical potential in the double layer must be foundonlyfrom the integral form of the charge-balance equation in the double layer. Equations were derived to calculate the rate constant of the Adsorption process in a flow cell for short and long times and the time needed to attain the equilibrium state for the Adsorption processes. It is shown that the Adsorption Kinetics of polyelectrolyte over a wide range of times is governed by: (I) the Adsorption Kinetics of polyelectrolyte on a planar surface of the bare interface for short times, (II) the Adsorption Kinetics at the interface as well as simultaneous diffusion in the adsorbed and double layers for intermediate times, and (III) the Adsorption Kinetics at the interface for long times.
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Overshoots of Adsorption Kinetics
Journal of Colloid and Interface Science, 1996Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A new theoretical approach to studying overshoots in Adsorption Kinetics has been developed in which surface conformational Kinetics are introduced onto a solid interface. It is found that these Kinetics cause, under certain conditions, an overshoot or oscillation in both the surface concentration and adsorbed concentrations. The criterion for overshoot and oscillation depends on the ratio, ϵ, of the rate constant of desorption,K−, and the rate constant of the conformational Kinetics,K*. Simple formulas for calculating the Adsorption over a wide range of time for the kinetic-controlled, the kinetic-diffusion-controlled, and the kinetic-diffusion-conformational-controlled Adsorption are derived.
Shahamat U Khan - One of the best experts on this subject based on the ideXlab platform.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (DeltaG(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (Delta G(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine. (c) 2009 Elsevier B.V. All rights reserved.
Leonid K. Filippov - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Surface Tension and Adsorption Kinetics from Micellar Solutions on Planar Surfaces
Journal of Colloid and Interface Science, 1997Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A qualitative theory of the dynamic surface tension and Adsorption Kinetics from micellar surfactant solutions on a planar surface is developed for the kinetic–diffusive-controlled Adsorption process obeying any Adsorption Kinetics on a planar surface and any micellization–demicellization Kinetics in the bulk. The time-dependent Adsorption and dynamic surface tension is obtained in an analytical form for short and long times. It is shown that the Adsorption process and dynamic surface tension over a wide range of surfactant (monomer) concentrations is governed by: (I) the Adsorption Kinetics of monomers and micelles for short times (0 ≤t ≤ tcr1), (II) the Adsorption Kinetics of monomers and micelles on a planar surface and the micellization–demicellization Kinetics in the bulk, and the diffusion of monomers and micelles for intermediate times (tcr1≤ t ≤ tcr2), and (III) the diffusion of monomers and micelles for long times (t ≥ tcr2). Formulas were derived to estimate the relaxation timestcr1,tcr2, and the parameters characterizing the Adsorption process over a wide range of times. The existence of the (I), (II), and (III) regimes are justified by using the experimental data for the dynamic surface tension of a micellar Brij 58 solution.
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Adsorption Kinetics of Polyelectrolytes on Planar Surfaces in Flow Cell
Journal of Colloid and Interface Science, 1997Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A quantitative theory of kinetic-diffusive-convective Adsorption in a flow cell for polyelectrolyte and mixtures of ions in solutions onto planar surfaces in the framework of the Nernst–Planck approach has been developed by using the new approaches: (a) The effect of the convective transport is estimated in the analytical form. The boundary condition for the rate of Adsorption at the interface (y= 0) is derived for the kinetic-diffusive-convective-controlled Adsorption in a flow cell, taking into account both the normal and the axial fluxes in the flow cell. (b) The total electrical potential in the double layer, ϕ(x,y,t), does not equal the electrical potential, ϕρ(x,y,t), due to the total electrical charge, ρ(x,y,t), in the double layer. It is shown that the total electrical potential in the double layer must be foundonlyfrom the integral form of the charge-balance equation in the double layer. Equations were derived to calculate the rate constant of the Adsorption process in a flow cell for short and long times and the time needed to attain the equilibrium state for the Adsorption processes. It is shown that the Adsorption Kinetics of polyelectrolyte over a wide range of times is governed by: (I) the Adsorption Kinetics of polyelectrolyte on a planar surface of the bare interface for short times, (II) the Adsorption Kinetics at the interface as well as simultaneous diffusion in the adsorbed and double layers for intermediate times, and (III) the Adsorption Kinetics at the interface for long times.
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Overshoots of Adsorption Kinetics
Journal of Colloid and Interface Science, 1996Co-Authors: Leonid K. Filippov, Nadezhda L. FilippovaAbstract:Abstract A new theoretical approach to studying overshoots in Adsorption Kinetics has been developed in which surface conformational Kinetics are introduced onto a solid interface. It is found that these Kinetics cause, under certain conditions, an overshoot or oscillation in both the surface concentration and adsorbed concentrations. The criterion for overshoot and oscillation depends on the ratio, ϵ, of the rate constant of desorption,K−, and the rate constant of the conformational Kinetics,K*. Simple formulas for calculating the Adsorption over a wide range of time for the kinetic-controlled, the kinetic-diffusion-controlled, and the kinetic-diffusion-conformational-controlled Adsorption are derived.
Guangcai Chen - One of the best experts on this subject based on the ideXlab platform.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (DeltaG(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (Delta G(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine. (c) 2009 Elsevier B.V. All rights reserved.
Yiquan Zhou - One of the best experts on this subject based on the ideXlab platform.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (DeltaG(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine.
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Adsorption Kinetics isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes
Journal of Hazardous Materials, 2009Co-Authors: Guangcai Chen, Xiaoquan Shan, Yiquan Zhou, Xiue Shen, Honglin Huang, Shahamat U KhanAbstract:The Adsorption Kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the Adsorption Kinetics. The calculated thermodynamic parameters indicated that Adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (Delta G(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low Adsorption affinity of MWCNTs for atrazine. (c) 2009 Elsevier B.V. All rights reserved.