Yeast-biotemplate-assisted fabrication of self-phosphorus doped Co3O4@C hollow architecture for ciprofloxacin degradation via peroxymonosulfate activation: Performance, mechanism and toxicity evaluation

Sustainable development of highly active catalysts for peroxomonosulfate (PMS) activation to destruct organic pollutants in wastewater has irreplaceable significance, but remains a challenge. Herein, we report the successful preparation of P-doped Co3O4 integrated porous carbon hollow architecture (Co3O4@PC-HM) using spherical yeast as a natural biological template and cobalt nitrate as a cobalt source. The unique hollow microspherical structure endows Co3O4@PC-HM with large specific surface area for providing copious surface-exposed active sites, and the self-P doping facilitates the electron transfer rate, which concomitantly contribute to boosting the PMS activation for ciprofloxacin (CIP) degradation. Specifically, the Co3O4@PC-HM exhibits an excellent performance for activating PMS to degrade CIP with a removal efficiency of 95% in 20 min. Quenching experiments and electron paramagnetic resonance tests indicate the coexistence of radical and non-radical pathways in the Co3O4@PC-HM/PMS system, among which 1O2 and SO4•− play the dominant roles in CIP degradation. Simultaneously, four possible pathways of CIP degradation with the Co3O4@PC-HM/PMS system are proposed. Toxicity evaluation based on ECOSAR procedure and the growth status of mung bean roots reveal that the degradation process catalyzed by the Co3O4@PC-HM/PMS system efficiently decreases the toxicity of CIP. The natural biological template strategy has guiding significance for the synthesis of other hollow structure for versatile applications.