Authors: K S Low C K Lee S M Mak
Publish Date: 2004/11/10
Volume: 38, Issue: 8, Pages: 629-640
Abstract
The sorption characteristics of citric acid modified wood to remove copper and lead ions from aqueous solution under batch conditions have been investigated Sorption was pH dependent with increasing uptake at higher pH values The kinetics of sorption for both ions was rapid with 90 sorption taking place within the first 60 min regardless of its initial concentration Sorption can be explained by a secondorder kinetics model from which the rate constant the equilibrium sorption capacity and the initial rate were calculated From these parameters the predictive models for Cu and Pb sorbed qt in time t and at an initial concentration Co are given by qt=Cot031Co−229+004Co+519t and qt=Cot/006Co−659+001Co+448t for Cu and Pb respectively Using these models the predicted and experimental uptakes of Cu and Pb were compared and discussed Maximum sorption capacities of modified wood under present experimental conditions were 2370 and 8264 mg/g for Cu and Pb respectively However for untreated wood the corresponding values were 256 and 771 mg/g indicating a tenfold increase in sorption upon citric acid modification Ethylene diamine tetraacetic acid and nitrilotriacetic acid complexed with both ions render sorption less favorably However salicylic acid had little influence In a binary system Pb ions were more favorably sorbed than Cu ions which could be due to the larger ionic radius of the former ions
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