Simultaneous removal of arsenic and antimony on high-index TiO 2 (HTiO 2 )

Abstract

Arsenic (As) and antimony (Sb) are toxic elements. They pose an emerging environmental risk and threaten human health. However,the removal of As and Sb remains a contemporary challenge due to the lack of knowledge in their surface chemistry and efficient adsorbent. In this study,the adsorption reaction of As and Sb on high-index {201} TiO2 (HTiO2) was examined. The results show that the adsorption isotherms of As(Ⅲ),Sb(Ⅲ),As(Ⅴ),and Sb(Ⅴ) on HTiO2 conformed to the Langmuir model with a maximum adsorption capacity of 0.407,0.861,0.197,and 0.181 mmol·g-1,respectively. The kinetics of As and Sb adsorption on HTiO2 followed the pseudo-second order reaction,suggesting that chemical adsorption was the rate-controlling step. The adsorption pH envelope experiments demonstrated that pH had a negligible effect on As(Ⅲ) adsorption. Sb(Ⅲ) adsorption was enhanced with increasing pH and then decreased. The adsorption of As(Ⅴ) and Sb(Ⅴ) was favorable at acidic pH and decreased with the increase in pH. Zeta potential shows that the HTiO2 surface was negatively charged over the full pH range upon As and Sb adsorption,indicating the formation of negatively charged inner-sphere As and Sb complexes on HTiO2. This study provides new information for simultaneous As and Sb removal from contaminated water.