Enhanced adsorption of antimonate by ball-milled microscale zero valent iron/pyrite composite: adsorption properties and mechanism insight.

Abstract

Ball-milling is considered as an economical and simple technology to produce novel engineered materials. The ball-milled microscale zero valent iron/pyrite composite (BM-ZVI/FeS2) had been synthesized through ball-milling technology and applied for highly efficient sequestration of antimonate (Sb(V)) in aqueous solution. BM-ZVI/FeS2 exhibited good Sb(V) removal efficiency (≥ 99.18%) at initial concentration less than 100mg Sb(V)/L. Compared to ball-milled zero valent iron (ZVI) and pyrite (FeS2), BM-ZVI/FeS2 exhibited extremely higher removal efficiency due to the good synergistic adsorption effect. BM-ZVI/FeS2 showed efficient removal performance at broad pH (2.6-10.6). Moreover, the coexisting anions had negligible inhibition influence on the Sb(V) removal. The antimony mine wastewater can be efficiently remediated by BM-ZVI/FeS2, and the residual Sb(V) concentrations (< 0.96μg/L) can meet the mandatory discharge limit in drinking water (5μg Sb/L). Experimental and model results demonstrated that endothermic reaction and chemisorption were involved in Sb(V) removal by BM-ZVI/FeS2. The XRD and XPS analyses confirmed that the complete corrosion of ZVI occurred on BM-ZVI/FeS2 after Sb(V) adsorption, resulting in the enhanced Sb(V) sequestration. Mechanism analyses showed that the excellent removal performance of BM-ZVI/FeS2 was ascribed to the high coverage of iron (hydr)oxide oxidized from ZVI. Because of the advantages of economical cost, high Sb(V) removal capacity and easy availability, BM-ZVI/FeS2 offers a promising adsorbent for Sb(V) remediation.