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 ([email protected]42−) that exhibited a maximum adsorption capacity of 101.3 mg/g with wide pH applicability (pH 3−9). This material have ~2.5 times higher adsorption capacity than that of pure zirconium alginate hydrogel beads ([email protected]) and it was ascribed to ion exchange between SO42− and F− on the surface of [email protected]42−, 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 [email protected]42− was energetically favorable than OH− and F− in [email protected] In addition, 310 bed volumes (BV) of effluent was realized via column adsorption of groundwater containing fluoride on [email protected]42− and indicated that it is a promising candidate for mitigating the problem of fluoride-containing groundwater.