Removal of F− from Water Using Templated Mesoporous Carbon Modified with Hydrated Zirconium Oxide

Abstract

Three types of MgO-templated mesoporous carbon possessing different specific surface area and pore size distribution were modified with hydrated zirconium oxide (ZrO2·xH2O) to prepare fluoride anion (F−) adsorbents. ZrO2·xH2O was synthesized through the auto-hydrolysis of zirconium oxychloride (ZrOCl2) in water under the coexistence of mesoporous carbon. X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that the mesoporous carbon surfaces were coated with mainly amorphous ZrO2·xH2O. Capabilities of aqueous F− removal of the prepared adsorbents and the unmodified mesoporous carbons were compared. The F− uptake by the prepared adsorbents was larger than that observed using unmodified carbons, indicating that the F− adsorption capacity was improved through the ZrO2·xH2O coating. Moreover, the adsorption capability was found to depend on the pore size of the mesoporous carbons. The F− uptake decreased as pH of F− solution increased. Protonation and deprotonation of ZrO2 were found to affect the F− adsorption.