纳米核壳Co@NC催化剂活化过氧乙酸降解磺胺甲噁唑

Degradation of SMX with Peracetic Acid Activated by Nano Core-shell Co@NC Catalyst

过氧乙酸[PAA,CH3C(O)OOH]作为一种新兴的氧化剂,在处理污水中难降解有机污染物中受到了越来越多的关注.通过蚀刻方法制备出纳米核壳Co@NC催化剂,并将其用于活化PAA降解污水中磺胺甲噁唑(SMX).结果表明,当控制催化剂投加量为0.02 g·L^(-1)、PAA浓度为0.12mmol·L^(-1)和SMX浓度为10μmol·L^(-1)时,反应5 min时SMX的去除率即可达到98%,且降解SMX的速率常数为0.80 min^(-1).SMX降解效率随催化剂添加量和PAA浓度提高而显著增加.结果发现核壳Co@NC/PAA体系在近中性条件下(pH为6.0~8.0)可获得最佳的SMX降解效果,酸性或碱性条件均不利于SMX去除.HCO_(3)^(-)和腐殖酸对该催化体系存在显著抑制,而Cl-抑制作用较弱.此外,通过自由基淬灭实验和电子顺磁共振(EPR)研究发现,乙酰氧自由基(CH_(3)CO_(2)·)和乙酰过氧自由基(CH_(3)CO_(3)·)为该体系中降解SMX的主要活性氧物种.进一步采用U-HPLC-Q-Exactive Orbitrap HRMS测定了该体系中SMX的降解产物,并提出了SMX可能的降解路径.同时,催化剂循环利用实验表明,纳米核壳Co@NC催化剂具有较好的催化稳定性和重复利用性.

Peracetic acid(PAA),as a new oxidant,has attracted increasing attention in the treatment of refractory organic pollution in sewage.In this study,the nano core-shell Co@NC catalyst was prepared via etching and used to activate PAA to degrade sulfamethoxazole(SMX)in sewage.The results indicated that the degradation rate of SMX reached 98%,and its reaction rate constant was 0.80 min^(-1) under optimal conditions(catalyst dosage=0.02 g·L^(-1),PAA concentration=0.12 mmol·L^(-1),pH=7,SMX concentration=10μmol·L^(-1)).With the increase in PAA concentration and core-shell Co@NC dosage,the degradation efficiency of SMX increased.The study found that the core-shell Co@NC/PAA system had the best degradation effect on SMX under near-neutral conditions(pH 6.0-8.0),and both acidic and alkaline environments were not conducive to SMX degradation.HCO3-and humic acid showed significant inhibition on the degradation of SMX,whereas Cl-showed weak inhibition.In addition,through a free radical quenching experiment and electron paramagnetic resonance(EPR)detection,acetoxy radical(CH_(3)CO_(2)CO_(3)·)were the main active species for the degradation of organic pollutants in the system.Transformation products(TPs)of SMX were analyzed by U-HPLC-Q-Exactive Orbitrap HRMS,and a possible degradation path of SMX was proposed.At the same time,the catalyst recycling experiment showed that the nano core-shell Co@NC catalyst had good stability and reusability.