Determination of equilibrium and kinetic parameters of the adsorption of Cr(III) and Cr(VI) from aqueous solutions to Agave lechuguilla biomass

Abstract

This investigation reveals the capability of Agave lechuguilla for trivalent and hexavalent chromium removal from aqueous solutions. Experimentation included pH profile, time dependence, adsorption capacity(K F and QL), adsorption intensity (n and RL) and saturation capacity ( qs) studies. Batch experiments were conducted at 22° C to characterize and model the adsorption equilibrium as well as biomass adsorption rates. pH 4 was the optimum for Cr(III) binding, while Cr(VI) optimum binding was at pH 2. Time profileexperiments indicated that the adsorption of Cr(VI) by lechuguilla biomass was time-dependent and that ofCr(III) was not. Kinetic models demonstrated that a pseudo-second order reaction model best described thekinetic data for Cr(VI). The adsorption isotherms showed that the binding pattern for Cr(VI) followed theFreundlich isotherm model, while that for Cr(III) followed the Langmuir isotherm.