Masashi Hatanaka
Abstract
A useful formulation of ion-adsorption kinetics is introduced based on our recent researches. The chemical reaction kinetics and diffusion kinetics are simultaneously analyzed combining with the Einstein’s viscosity formula. The rate-determining steps are quantitatively determined by estimating ...
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A useful formulation of ion-adsorption kinetics is introduced based on our recent researches. The chemical reaction kinetics and diffusion kinetics are simultaneously analyzed combining with the Einstein’s viscosity formula. The rate-determining steps are quantitatively determined by estimating the relative magnitude of the kinetics resistances in the boundary film and the particle. The key concept of this method is an addition theorem of film-diffusion kinetic resistance and the particle-diffusion kinetic resistance. While in hydrophilic polymers, the thickness of boundary film decreases due to the attractive force between the ion and the surface, in hydrophobic polymers, it increases with the amount of hydrophobic components. This is confirmed by using chitosan resins with hydrophilic/hydrophobic components. The experiments are based on the batch method, and degree of film-diffusion control and particle-diffusion control is determined simultaneously. The film mass-transfer coefficient in the boundary film is also determined from a simple plotting of the experimental data. This method is also applicable to ion-exchange kinetics by summing the kinetic resistances at each step in the ion-exchange reaction and the mutual diffusion. Our method will serve as a guiding tool for designing of adsorption agents and ion-exchangers. Copyright © VBRI Press.
Karuna Nalwa; Anupama Thakur; Neeta Sharma
Abstract
In the present study nanoparticles of zinc oxide (ZnO) were synthesized by simple solution based approach and used as an adsorbent for the removal of Cu(II) ions from aqueous solution. ZnO nanoparticles were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Dynamic ...
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In the present study nanoparticles of zinc oxide (ZnO) were synthesized by simple solution based approach and used as an adsorbent for the removal of Cu(II) ions from aqueous solution. ZnO nanoparticles were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). TEM confirmed the formation of zinc oxide nanoparticles in the size range of 10-11 nm. Adsorption capacity of ZnO for removing Cu(II) ions from aqueous solutions was investigated at different pH, as a function of contact time, metal ion concentration and the amount of adsorbent. Moreover, adsorption isotherms and kinetics was studied to understand the nature and mechanism of adsorption. A high percentage removal (98.71%) of Cu(II) from its aqueous solutions at pH 5 and at initial heavy metal ion concentration of 300 mg/l by ZnO particles was achieved. The adsorption isotherm was well described by Freundlich isotherm model(R2= 0.999). The adsorption kinetics data was well fitted by the pseudo-second-order rate model with a high regression coefficient. The above results suggest that ZnO nanoparticles can be used as potential adsorbent for the efficient removal of heavy metals from aqueous solutions. Copyright © 2017 VBRI Press
