In-situ S-doped mesoporous carbon as metal-free catalyst for efficient degradation of oxytetracycline with peroxydisulfate: Performance and mechanism

In-situ S-doped mesoporous carbons (ACS) were fabricated through template method by using sucrose as carbon source and basic magnesium sulfate whisker (513 MOS) as both sulfur source and template. ACS were highly efficient for the activation of peroxydisulfate (PDS) towards aqueous oxytetracycline (OTC) removal. Investigation on the effects of 513 MOS/ sucrose mass ratio on the physicochemical properties and catalytic performance indicated that higher specific surface area, pore volume, thiophene-S (C-S-C) group content as well as carbon skeleton defects contributed to the excellent activity of ACS. 100 % of OTC removal was achieved by ACS-2 within 30 min under the optimal reaction condition, which outperformed most reported transition-metal based and carbon-based heterogeneous catalysts. ACS-2 also showed excellent adaptability with wide pH range as well as various pollutants. Mechanism studies showed that PDS were activated through radical and non-radical pathways, and four plausible degradation pathways of OTC were proposed according to the intermediates identification. This work provides a straightforward method for the construction of metal-free sulfur-doped activated carbons with highly activity for the removal of refractory organic pollutants.