Zirconium decontamination from aqueous media using lateritic minerals

Abstract

Abstract The sorption behavior of zirconium on minerals from a lateritic weathering has been carried out to evaluate its potential for the decontamination of zirconium ions from aqueous solutions. Various physico-chemical parameters such as selection of appropriate electrolyte, equilibration time, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature were studied in order to simulate the best conditions under which this material can be used as an adsorbent, employing batch method and radiotracer technique. Maximum adsorption was observed at 0.005 mol L−1 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 0.3 g of adsorbent for 1.499×10−4 mol L−1 zirconium concentration in five minutes equilibration time. Studies show that the adsorption of zirconium decreases with the increase in the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 7.5×10−5 to 3.0×10−3 mol L−1 zirconium concentration. The characteristic Freundlich constants i.e. 1/n = 0.55±0.03 and K=1.36×10−3±7.0×10−5 mol g−1 have been computed for the sorption system. The sorption mean free energy from the Dubinin–Radushkevich isotherm is 11.2±0.4 kJ mol−1 indicating ion-exchange mechanism of chemisorption. The uptake of zirconium increases with the rise in temperature (283-323 K). Thermodynamic quantities i.e. ΔG, ΔS and ΔH have also been calculated for the system. The sorption process was found endothermic.