Ultra-fast enrichment and reduction of As(V)/Se(VI) on three dimensional graphene oxide sheets-oxidized carbon nanotubes hydrogels.

The removals of arsenic and selenium pollutants are always urgent desires for the water security. In this study, both sorption and catalysis strategies were combined for the effective removals of As(V) and Se(VI) over magnetic graphene oxide sheets (GOs)-oxidized carbon nanotubes (OCNTs) hydrogels. The sorption behavior facilitated the operation of catalysis reactions, meanwhile, the catalytic reduction promoted the release of occupied sorption sites and then restarted a new sorption-catalysis cycle. The synergic effect of sorption and catalysis realized 258.2 mg g⁻¹ for As(V) enrichment capacity on MPG2T1, and ultra-fast sorption and catalysis equilibriums were identified within 9 min. In the case of Se(VI), a moderate enrichment performance was observed to be 46.2 mg g⁻¹. Similarly, the ultra-fast sorption and reduction of Se(VI) were realized within 2 min. In the competition experiments, only SO 4 ²⁻, SO 3 ²⁻, and HPO 4 ²⁻ showed interference for As(V) and Se(VI) removals. These results testified the superiority of the synergy effect of sorption and catalysis, and the feasibility of 3D magnetic GOs-OCNTs hydrogel in practical implementations. The effective removals of As(V) and Se(VI) were realized on the 3D GOs-OCNTs hydrogel based on ultra-fast sorption and catalysis behaviors within a few minutes. Image 1 • The synergistic effects of sorption and catalysis demonstrated the effective removals of As(V) and Se(VI). • Ultra-fast sorption was realized within 9 min for As(V) removal, and 2 min for Se(VI), respectively. • Effective catalysis was achieved within 2 min for the reductions of As(V) and Se(VI). [ABSTRACT FROM AUTHOR]