Remediation of antimony-contaminated tap water using granular TiO2 column

Abstract

Environmental contextAntimony (Sb) contamination from mining is an emergent environmental issue, and there is an urgent need for the development of effective water treatment technology. This study reports a complete Sb remediation strategy using granular titanium dioxide as the adsorbent, and describes adsorbent manufacture, Sb adsorptive removal and regeneration of the adsorbent. The findings highlight a practical way for on-site remediation of Sb-contaminated water. AbstractAntimony (Sb) mining endorses the development of Sb remediation technology to reduce its contamination level and protect public health. In this study, a treatment process based on granular TiO2 was proposed to remediate the Sb-contaminated tap water at mining sites. The Langmuir isotherms indicated that the maximum adsorption capacity on granular TiO2 was 142mgg−1 for SbIII and 43mgg−1 for SbV. The kinetics results suggested that Sb adsorption conformed to the Weber–Morris intraparticle diffusion model. The adsorption of SbV featured the anionic adsorption characteristics, which were significantly inhibited at pH>8. Approximately, 586 bed volumes of tap water with an average SbV concentration of 324µgL−1 were filtered before the effluent concentration exceeded 6µgL−1 using a granular TiO2 column. The PHREEQC program integrated with charge distribution multi-site complexation (CD-MUSIC) modelling and a one-dimensional transport block was performed to predict the SbV breakthrough curve. The results revealed that the existence of Ca2+ significantly promoted SbV adsorption. Furthermore, the breakthrough curves of SbV and Ca2+ were well simulated after considering the effects of Ca2+ adsorption and the Ca-Sb-TiO2 ternary surface complex. Granular TiO2 can be regenerated and reused, and the solid residue from regeneration can be recycled. The insights of this study help to further understand the environmental chemistry of Sb on metal oxides, which provides a practical solution for Sb removal.