Removal of Cr(VI) species from water with a newly-designed adsorptive treatment train

In this study, a feasible treatment train was designed to remove Cr(VI) species from water. In the first place, Cr(VI) anionic species were chemically deoxidized and reduced to lower toxic Cr3+ cations with sodium pyrosulfite as the reducing reagent. Secondly, the intentionally-designed alkaline adsorbents that exhibited weak alkalescence in water were employed to precipitate and adsorb Cr3+ cations with no pH adjustment. Finally, concentrated alkaline solution was used to dissolve Cr(III) species that were anchored on adsorbent surfaces and replenish surface hydroxyl ions for further reuse. The whole treatment train could be seamlessly integrated into the conventional removal procedure for Cr(VI) contaminants in sewage plants. More feasible, easier operation, higher efficiency and better cyclicity rendered this treatment train a more promising future in practical sewage disposal.