Preparation and evaluation of thiol-functionalized activated alumina for arsenite removal from water

Arsenic species such as arsenite [As(III)] and arsenate [As(V)] are known human carcinogens. Though lots of metal oxide adsorbents have been developed for removal of As(V), they are much less effective for As(III) adsorption. In this study, various inorganic-organic hybrid adsorbents bearing thiol groups have been prepared by modifying activated alumina (AA) with mercaptopropyl-functionalized silica under different experiment conditions. Raman spectra demonstrated the successful functionalization of AA and verified the formation of As-S complexes after As(III) adsorption. Batch experiments were applied to evaluate the As(III) adsorption performance of the hybrid adsorbents. Compare with AA, the hybrid adsorbents exhibited enhanced adsorption abilities for As(III) due to the introduction of thiol groups, and as the thiol loading increased, the uptake of As(III) increased. Experimental results indicated that the hybrid adsorbents still maintained the merit of the AA for As(V) adsorption. Based on the results, one hybrid adsorbent referred to as BL(AA)(30)(MPTS)(3.3) has been selected by consideration of not only the adsorption capacity but also its environmentally friendly and cost-effective production. The investigation has indicated that the hybrid adsorbents are very promising for As(III) removal from water.