A well-performing N, S double doping-carbon/metal composite catalyst prepared from used adsorbent for highly efficient degradation of floatation reagents

The carbon/metal catalyst has gained increasing attention due to its outstanding properties such as high activation capacity and environmental friendliness, while the nonmetallic heteroatom doped into the carbon matrix could further improve its performance. This study prepared a well-performing N, S double doping-carbon/metal composite catalyst by calcinating the spent metal-based adsorbents for organics. The composite catalyst showed improving catalytic performance with a carbon-wrapped Fe and Mn particle structure. For the degradation of 100 mg/L butyl amine (BA), such the composite catalyst delivered a high removal efficiency of 90% within 30 min in the presence of 0.2 g/L oxidant and 0.4 g/L catalyst at 25 °C and original pH value. Reactive species including SO4•-, •OH, O2•- and 1O2 contributed to the decomposition of BA molecules. In-depth mechanism exploration has shown that the carbon networks could serve as the electron-transfer mediator to accelerate the degradation rate and enhance the anti-interference ability of the degradation system. At the same time, the generation of metal-free active sites of N and S also assisted the BA degradation, in which pyrrole N, S22− and Sn2− with stronger reducibility played crucial roles in the degradation process. This study has provided new insight and a novel approach for reusing exhausted environmental remediation materials to construct efficient advanced oxidation catalysts.