Re-use of agricultural wastes for the removal and recovery of Zr(IV) from aqueous solutions

Abstract

This study assesses the feasibility of Zr(IV) removal and recovery from aqueous solutions by novel biosorbents prepared from selected agricultural wastes. Sugarcane bagasse was selected for further investigation after showing increased biosorption capacity during the initial screening experiment. The biosorption efficiency of native (untreated), SDS-treated and immobilised bagasse for Zr(IV) removal was studied and optimization of the experimental conditions carried out including pH, biosorbent weight, contact time, initial metal ion concentration and temperature to maximise adsorption. Sorbent–sorbate reaction behaviour was estimated by fitting equilibrium data by non-linear and transformed linear forms of the Langmuir, Freundlich and Redlich–Peterson isotherms as well as pseudo-first and second-order kinetic models. The best fitting isothermal or kinetic model was optimized by comparing linear and non-linear R2 value and non-linear regression error functions. H2SO4 proved to be the most effective desorbing agent in recovery of the sorbed Zr(IV) ions from all forms of bagasse. Biosorbent characterisation and effectiveness of the process was confirmed by Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX). The data illustrate that native (untreated), SDS-treated and immobilised bagasse have great potential to remove and recover Zr from wastewater.