Yuh-Shan Ho

PSEUDO-SECOND ORDER MODEL FOR SORPTION PROCESSES

A literature review of the use of sorbents and biosorbents to treat polluted aqueous effluents containing dyes:organics or metal ions has been conducted. Over 70 systems have been reported since 1984 and over 43 of these reported the mechanism as being a pseudo-first order kinetic mechanism. Three sorption kinetic models are presented in this paper and have been used to test 11 of the literature systems previously reported as first order kinetics and one system previously reported as a second order process. In all 12 systems, the highest correlation coefficients were obtained for the pseudo-second order kinetic model.

Sorption of dye from aqueous solution by peat

The sorption of two dyes, namely, Basic Blue 69 and Acid Blue 25 onto peat has been studied in terms of pseudo-second order and first order mechanisms for chemical sorption as well as an intraparticle diffusion mechanism process. The batch sorption process, based on the assumption of a pseudo-second order mechanism, has been developed to predict the rate constant of sorption. the equilibrium capacity and initial sorption rate with the effect of agitation, initial dye concentration and temperature. An activation energy of sorption has also been evaluated with the pseudo-second order rate constants. A comparison of the equilibrium sorption capacity evaluated has been made from pseudo-second order model and Langmuir isotherm.

The kinetics of sorption of divalent metal ions onto sphagnum moss peat

A pseudo-second order rate equation describing the kinetics of sorption of divalent metal ions onto sphagnum moss peat at diAerent initial metal ion concentrations and peat doses has been developed. The kinetics of sorption were followed based on the amounts of metal sorbed at various time intervals. Results show that sorption (chemical bonding) might be rate-limiting in the sorption of divalent metal ions onto peat during agitated batch contact time experiments. The rate constant, the equilibrium sorption capacity and the initial sorption rate were calculated. From these parameters, an empirical model for predicting the sorption capacity of metal ions sorbed was derived. # 2000 Elsevier Science Ltd. All rights reserved

A COMPARISON OF CHEMISORPTION KINETIC MODELS APPLIED TO POLLUTANT REMOVAL ON VARIOUS SORBENTS

A comparison of kinetic models describing the sorption of pollutants has been reviewed. The rate models evaluated include the Elovich equation, the pseudo-first order equation and the pseudo-second order equation. Results show that chemisorption processes could be rate limiting in the sorption step. The pseudo-second order equation may be applied for chemisorption processes with a high degree of correlation in several literature cases where a pseudo-first order rate mechanism has been arbitrarily assumed.

Citation review of Lagergren kinetic rate equation on adsorption reactions

This study presents a literature review concerning the preciseness of over 170 publications citing the original Lagergrens paper in kinetics equation for solute adsorption on various adsorbents. This equation applies to a range of solid-liquid systems such as metal ions, dyestuffs and several organic substances in aqueous systems onto various adsorbents. The main objectives are to manifest different forms of citations presented and offers a correct reference style for citing the original Lagergrens paper published in 1898.This study presents a literature review concerning the preciseness of over 170 publications citing the original Lagergrens paper in kinetics equation for solute adsorption on various adsorbents. This equation applies to a range of solid-liquid systems such as metal ions, dyestuffs and several organic substances in aqueous systems onto various adsorbents. The main objectives are to manifest different forms of citations presented and offers a correct reference style for citing the original Lagergrens paper published in 1898.

Kinetic Models for the Sorption of Dye from Aqueous Solution by Wood

The sorption of Basic Blue 69 and Acid Blue 25 onto wood has been studied in terms of pseudo-second order, intraparticle diffusion and pseudo-first order chemical sorption processes. The batch sorption model, based on the assumption of a pseudo-second order mechanism, has been developed to predict the rate constant of sorption, the equilibrium capacity and initial sorption rate with the effect of initial dye concentration, wood particle size and temperature. An equilibrium capacity of sorption has been evaluated with the pseudo-second order rate equation as well as by the Langmuir isotherm and operating line method. In addition, an activation energy of sorption has also been determined based on the pseudo-second order rate constants.

The sorption of lead(II) ions on peat

The sorption of lead ions from aqueous solution onto peat has been studied. Kinetic studies have been carried out using an agitated batch and the effect of varying process parameters has been investigated; these include initial lead ion concentration, peat particle size, solution temperature and agitation speed. The data were analyzed using a pseudo-first order Lagergren equation and the data were correlated using a two-step first order reaction mechanism.

EQUILIBRIUM ISOTHERM STUDIES FOR THE SORPTION OF DIVALENT METAL IONS ONTO PEAT: COPPER, NICKEL AND LEAD SINGLE COMPONENT SYSTEMS

The sorption of three divalent metal ions — copper, nickel and lead — from aqueous solution onto peat in single component systems has been studied and the equilibrium isotherms determined. The experimental data have been analysed using the Langmuir, Freundlich, Redlich-Peterson, Toth, Temkin, Dubinin-Radushkevich and Sips isotherm models. In order to determine the best fit isotherm for each system, six error analysis methods were used to evaluate the data: the coefficient of determination, the sum of the errors squared, a hybrid error function, Marquardts percent standard deviation, the average relative error and the sum of absolute errors. The error values demonstrated that the Sips equation provided the best model for the three sets of experimental data overall.

KINETICS OF POLLUTANT SORPTION BY BIOSORBENTS: REVIEW

A review of the mechanisms of solute sorption onto various biosorbents has been performed. The mechanisms have been subdivided into reaction based systems and diffusion based systems and the literature has been reviewed in accordance with these two groups. The range of solute-sorbent systems reviewed include metal ions, dyestuffs and several organic substances in aqueous systems onto a wide range of biosorbents and mineral earths. Extensive tables are presented summarising isotherm types, sorption capacities, kinetic models which have been applied particularly to biosorbent systems but also to many other adsorbent materials.

Removal of copper ions from aqueous solution by tree fern

Tree fern, an agricultural by-product, was used for the sorptive removal of copper ions from aqueous solution. The experimental data was analysed by Langmuir, Freundlich and Redlich-Peterson isotherms. The equilibrium sorption capacity of copper ions was determined from the Langmuir equation and found to be 11.7 mg/g. A batch sorption model, based on the assumption of the pseudo-second-order mechanism, was developed to predict the rate constant of sorption, the equilibrium sorption capacity and the initial sorption rate with the effect of initial copper ion concentration and the tree fern dose. Various thermodynamic parameters, such as Delta G(0), Delta H(0) and Delta S(0), have been calculated. The thermodynamics of copper ion/tree fern system indicates spontaneous and endothermic nature of the process.