Oxidation of 2,4-dichlorophenol by non-radical mechanism using persulfate activated by Fe/S modified carbon nanotubes

The aim of this study was to develop a new approach for the activation of persulfate (PS) based on carbon nanotubes (CNTs). Fe/S modified carbon nanotubes (Fe/S-CNTs) were synthesized via impregnation-precipitation in the aqueous-phase synthesis method. The morphologies and chemical states of the catalysts were characterized and 2,4-dichlorophenol (2,4-DCP) was selected to investigate the degradation performance using Fe/S-CNTs with PS. The results reveal that the Fe/S-CNTs catalysts can significantly accelerate the removal of 2,4-DCP compared to single PS or PS/CNTs. The catalytic capacity is also enhanced by S modification and is affected by the solution pH. The iron loading content, PS concentration and catalyst dosage could play important roles in the degradation. A non-radical process of 2,4-DCP degradation is demonstrated for the first time in the results of the radical scavengers and chloride ionic, as well as persulfate decomposition. It is suggested that PS is first bonded with the sp(2)-hybridized system and activated by iron oxide particles and iron-sulfur complexes, then it reacts rapidly with the adsorbed 2,4-DCP.