Novel reusable sulfate-type zirconium alginate ion-exchanger for fluoride removal

It is still a challenge to eliminate efficiently fluoride ion from groundwater, especially to design and synthesis an adsorbent possessing high adsorption capacity, recyclability and wide pH application conditions. Herein we present millimeter-sized sulfate-type zirconium alginate hydrogel beads with 3D network structure (AHB@Zr-SO42-) that exhibited a maximum adsorption capacity of 101.3 mg/g with wide pH applicability (pH 3-9). This material have similar to 2.5 times higher adsorption capacity than that of pure zirconium alginate hydrogel beads (AHB@Zr) and it was ascribed to ion exchange between SO42- and F- on the surface of AHB@Zr-SO42-, which was verified via ion chromatography measurement coupled with X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectrometer (FTIR Spectrometer) analysis. Density functional theory (DFT) calculations indicated that the ion exchange process between SO42- and F- in AHB@Zr-SO42- was energetically favorable than OH- and F- in AHB@Zr. In addition, 310 bed volumes (BV) of effluent was realized via column adsorption of groundwater containing fluoride on AHB@Zr-SO42- and indicated that it is a promising candidate for mitigating the problem of fluoride-containing groundwater. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.