Enhanced adsorption of hexavalent chromium from aqueous solutions on facilely synthesized mesoporous iron-zirconium bimetal oxide

Mesoporous iron-zirconium bimetal oxide (MIZO) which was templated by cetyltrimethylammonium bromide (CTAB) was facilely synthesized through co-precipitation for the first time. MIZO was applied in the adsorption of hexavalent chromium [Cr(VI)] in aqueous solutions, with comparison to ordinary iron-zirconium bimetal oxide (IZO). The properties of MIZO and IZO were characterized by N-2 adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscope (SEM), Zeta-sizer analyzer and X-ray Photoelectron Spectroscopy (XPS). In general, MIZO showed better performance than IZO within the Cr(VI) adsorption. The maximum adsorption capacity of MIZO was 59.88 mg/g, which was obviously greater than that of IZO (37.04 mg/g). Besides, MIZO had a wider pH tolerance range. When pH increased from 2 to 8, the Cr(VI) removal rate of MIZO decreased from 94% to 81% and that of IZO decreased from 88% to 43%. Further, MIZO had higher Cr(VI) removal than IZO when coexisting with common anions (chloride, sulfate, etc.) and regenerated by NaOH. The characterization of MIZO and IZO indicated that the enhanced adsorption of Cr(VI) on MIZO was closely related to its uniform mesoporous structure characteristics and high zeta potential. Based on the experiment results, MIZO has been proven to be an excellent adsorbent for Cr(VI). (C) 2015 Published by Elsevier B.V.