Ordered mesoporous MnO2 as a synergetic adsorbent for effective arsenic(iii) removal

Abstract

Ordered mesoporous MnO₂ nanoarrays were successfully prepared via a vacuum-assisted nanocasting route from an SBA-15 template. To achieve better purification performance for As(III), iron oxides with varied ratios were dispersed into the 2D hexagonal channels, and a series of FeMn-x adsorbents were obtained. Consisting of both iron and manganese oxides, these adsorbents could realize powerful oxidation and effective adsorption of As(III) simultaneously, revealing a synergetic arsenic removal process. The saturation adsorption capacity was 10.55 mg g⁻¹ and >95% adsorption stability could be reached within a relatively short time. Furthermore, owing to the optimum Fe/Mn ratio, the FeMn-2 sample could easily bring the residual concentration down to below 10 ppb, when dealing with trace As(III) concentrations as low as 300 ppb, which provides a convenient method to efficiently capture trace As(III) from water for in-depth purification.