W-doping enhanced cobalt sulfide catalyzing PMS-mediated phenol degradation: Performance optimization, mechanism analysis and toxicity verification

Phenol is a refractory organic pollutant, and developing efficient catalysts for its degradation is still a challenge. Conventional advanced oxidation processes have limitations in electron transfer rate and pH adaptability. We synthesized a tungsten-doped cobalt sulfide catalyst via a hydrothermal method for activating peroxymonosulfate (PMS) to degrade phenol. Under optimal doping conditions, the CW-1/PMS system achieved 100% phenol removal, with an 8-fold increase in the reaction rate constant compared to the undoped catalyst. Tungsten doping effectively promoted electron transfer and accelerated the Co 3+ /Co 2+ redox cycle. The system maintained high efficiency over a wide pH range and in the presence of common anions, though it was significantly inhibited by humic acid, demonstrating good environmental adaptability. The degradation pathway was elucidated by high-performance liquid chromatography-mass spectrometry (HPLC-MS) combined with density functional theory (DFT) analysis. The Ecological Structure-Activity Relationships (ECOSAR) model and phytotoxicity experiments indicated a significant reduction in the toxicity of the degradation products. This work provides theoretical insights and technical guidance for designing efficient catalysts and treating phenol-containing wastewater.