Cu location onto spherical SiO2@Mn make a profound difference for catalytic oxidative removal Na2S in waste water with air as an oxidant at ambient conditions

Abstract

Different location Cu species on the SiO2@Mn catalysts surface was prepared to form well-defined core-shell material for enhancing the catalytic efficiency of degrading Na2S in waste water. The modified location of Cu species was tuned through changing the order of impregnation. The species of Cu in the middle layer perform the best activity and selectivity. Integrating XRD, HAADF-STEM, H2-TRP, UV–vis, XPS, CV and Na2S removal tests, the decisive factor for improved the catalytic efficiency for Na2S removal probably is the unique structural advantages of Cu species in the middle layer, which produces higher ratio of Mn4+/(Mn4+ + Mn3+) and provides rich surface active oxygen. And Na2S in waste water could be degraded as high as 92.77% in 4 h with air as an oxidant at ambient conditions. Recycling experiments indicate that no significant deactivation occurred for the catalysts during tests in seven times. This work provides a novel sight for preparing high-efficient and stable catalysts for Na2S degradation.