Abstract

Nanoscale zero-valent iron (NZVI) and NZVI supported onto montmorillonite (NZVI-Mt) were synthetized and used in this study to remove Se-VI and As-V from water in monoand binary-adsorbate systems. The adsorption kinetics and isotherm data for Se-VI and As-V were adequately described by the pseudo-second-order (PSO) (r(2)>0.94) and Freundlich (r(2)>0.93) equations. Results from scanning electron microscopy showed that the dimension of the NZVI immobilized on the Mt was smaller than pure NZVI. Using 0.05 g of adsorbent and an initial 200 mg L-1 As-V and Se-VI concentration, the maximum adsorption capacity (q(max)) and partition coefficient (PC) for As-V on NZ(VI)-Mt in monocomponent system were 54.75 mg g(-1) and 0.065 mg g(-1).mu M-1, which dropped respectively to 49.91 mg g(-1) and 0.055 mg g(-1).mu M-1 under competitive system. For Se-VI adsorption on NZ(VI)-Mt in monocomponent system, q(max) and PC were 28.63 mg g(-1) and 0.024 mg g(-1).mu M-1, respectively. Values of q(max) and PC were higher for NZVI-Mt than NZVI and montmorillonite, indicating that the nanocomposite contained greater adsorption sites for removing both oxyanions, but with a marked preference for As-V. Future research should evaluate the effect of different operational variables on the removal efficiency of both oxyanions by NZVI-Mt.