Removal Of Aqueous Sb(V) By Adsorbents Loaded With Nano Hydrated Ferric Oxides

We fabricated two hybrid adsorbents by impregnating HFOs on the polymeric anion exchanger D201(HFO-201) and calcite sands (IOCCS), and then characterized their physicochemical properties and evaluated their adsorption for Sb(V) in terms of batch and column adsorption systems. Results indicated that in the pH range from3-9, decreasing solution pH enhanced Sb(V) removal efficiency of the both composites. Increasing temperature from293K to313K improved the uptake of Sb(V) by IOCCS while affected slightly on that of HFO-201. At the same temperature in this range, HFO-201exhibited much higher capacity for single Sb(V) system than IOCCS. Increasing ionic strength (NaN03) resulted in a significant drop in the capacity of HFO-201, while negligible influence was observed for IOCCS. The presence of chloride and sulfate posed more negative effects on adsorption of HFO-201than that of IOCCS. Silicate decreased the adsorption of both adsorbents significantly, nevertheless, IOCCS showed higher selectivity in adsorption of Sb(V). Calcium ions in the solution promoted their adsorption capacity and IOCCS was more promoted than HFO-201.The adsorption mechanism was subsequently probed by FTIR, XPS, and surface charge analysis. The results indicated that the preferable adsorption of Sb(V) by HFO-related hybrids was mainly attributed to the inner sphere complexation of Sb(V) and HFO. The enhanced adsorption of Sb(V) in the presence of Ca2+was probably due to the formation of HFO-Ca-Sb complexes. The zero point of charge (ZPC) of HFO did not change obviously after loading onto raw calcite sands (RCS). So it was speculated that the outstanding performance of IOCCS could be attributed to the better dispersion of HFO onto calcite sands, which had larger surface area than HFO-201.Column adsorption runs showed that Sb(V) was reduced to below5μg/L from initial30μg/L in the synthetic water, meeting the drinking water guideline in China. The treatable volume of IOCCS was～6times higher than that of HFO-201when the column was broken through.Finally, it is concluded that HFO coatings onto calcite sands possessed higher adsorption efficiency than that inside D201, implying RCS performs better as a support for HFO loading. Thus IOCCS might be a more effective approach than HFO-201in treatment of Sb(V) contaminated water.