Enhanced metal removal from aqueous solution by Fenton activated macrophyte biomass

Abstract

Eichhornia crassipes biomass was modified by Fenton treatment and its effectiveness for Zn2+ removal from contaminated water was investigated. The Fenton activation process was optimized by varying pH, contact time, temperature, macrophyte biomass/volume Fenton reagent ratio, and Fe/H2O2 ratio. The efficiency of the Zn2+ sorption process under different experimental conditions was also determined. Experimental data showed good fitting to Langmuir Freundlich and Dubinin–Radushkevich isotherm models. Maximum sorption capacity was 0.114 and 0.203mmolg−1 for raw and Fenton activated biomass (dose 5.0gL−1, pH 6.0), increasing 78% after Fenton activation. Adsorption of Zn2+ to activated biomass increased as the temperature increased. The thermodynamic parameters suggested that the process was spontaneous, governed by chemical adsorption and endothermic in nature. The kinetics of the Zn2+ adsorption was tested by five models (pseudo-first-order, pseudo-second order, Elovich, intraparticle diffusion and Bangham diffusion models). The correlation coefficients for the pseudo-second order kinetic model were the highest suggesting a chemical reaction mechanism although intraparticle diffusion could not be discarded. The practical implication of this study is the development of an effective and economic technology for Zn2+ removal from contaminated waters, which is especially useful when macrophyte material is locally available.