Antimonate and antimonite adsorption by a polyvinyl alcohol-stabilized granular adsorbent containing nanoscale zero-valent iron

Nanoscale zero-valent iron (Fe-0) has attracted increasing attention for hazardous ion removal. In this study, nanoscale Fe-0 was stabilized by polyvinyl alcohol (PVA) and fabricated to granules for stability and functional excellence. Then Sb(III) and Sb(V) removal from water was evaluated. The effects of contact time, initial Sb(III) and Sb(V) concentrations, pH and co-existing anions on the Sb removal efficiency were systematically investigated. Antimony adsorption was rapid and followed a pseudo-second rate law. The maximum adsorption capacity of granular PVA-Fe-0 was 6.99 and 1.65 mg/g for Sb(III) and Sb(V), respectively. High concentration levels of co-existing anions inhibited antimony removal, but little inhibition would be expected at their natural environmental concentrations in water. The antimony uptake mechanism by PVA-Fe-0 was investigated using XRD, XPS and FTIR characterizations. Fe was present in an acetalized PVA matrix before adsorption. It had been converted into magnetite (Fe3O4) after Sb(III) and Sb(V) adsorption. FTIR analyses confirmed the presence of active magnetite and magnetite's chemical binding to Sb(III) and Sb(V) after adsorption. The convenient handling properties combined with the good efficiency of PVA-Fe-0 granules suggests they are promising adsorbents for antimony removal from contaminated water. (C) 2014 Elsevier B.V. All rights reserved.