Three-dimensional Co–N/SBA-15/alginate hydrogels with excellent recovery and recyclability for activating peroxymonosulfate to degrade ciprofloxacin

Abstract A facile and environmentally friendly method to synthesize efficient catalysts for activating peroxymonosulfate (PMS) to degrade contaminants is highly important yet remains challenging. By combining the superiorities of ordered Co/N@ZS and alginate hydrogels, namely regular and stable channels, large specific surface area, outstanding hydrophilicity and unique three-dimensional structure, an excellent recovery and recyclability catalyst, Co0·6/N@ZS-SA, exhibited outstanding performance in activating 0.50 g/L PMS for ciprofloxacin degradation (20 mg/L) with a high degradation rate of 82.52%. The effect of diversified influencing parameters, stability and recyclability on the degradation efficiency was systematically investigated. More importantly, the composite hydrogel with excellent recovery and recyclability could still degrade more than 63.4% CIP after three consecutive reactions. In addition, combined EPR analysis and ROS quenching research indicated that HO•, SO4•−, O2•− and 1O2 were generated but CIP degradation dominated by the radical mechanism comprising the yield of SO4•−. Besides, the intermediate products were identified by LC-MS analyses to propose the possible degradation pathways.