Fe^(2+)/单过氧硫酸氢盐(PMS)体系降解水体中酮洛芬的机制研究

Degradation mechanism of ketoprofen by Fe^(2+)/ potassium peroxy monosulfate( PMS) oxidation process in aqueous

以酮洛芬(KTP)为目标污染物,研究了其在Fe^(2+)/单过氧硫酸氢盐(PMS)体系中的降解行为.溶液的pH值不仅会影响KTP的存在形态,而且也会影响Fe^(2+)/PMS体系中Fe^(2+)的形态,进而影响KTP的降解,结果表明,酸性条件有利于KTP的降解,当pH=3时降解效果达到最佳,降解率为66.87%.分别以乙醇和叔丁醇做为自由基猝灭剂,检测到体系中存在硫酸根自由基与羟基自由基,且酸性时以硫酸根自由基为主导,而中性和碱性时以羟基自由基为主导,说明随pH值的升高体系中发生了SO_4^(-·)向HO·转化.当HCO_3^-浓度从0增大至0.01 mmol·L^(-1)时,其对KTP的降解起到促进作用,继续增大至10 mmol·L^(-1)时,对KTP的降解起抑制作用.HA在0至10 mg·L-1浓度范围内对KTP的降解起到促进作用,继续增大至50 mg·L^(-1)时则表现出抑制作用.自然水体中低浓度的腐殖酸、碳酸氢盐对KTP的降解起到促进作用,而高浓度则表现为抑制作用;采用UPLC/MS/MS对KTP降解产物进行鉴定,推测KTP在Fe^(2+)/PMS体系下的降解途径主要涉及脱羧反应、酮基化反应和羟基化反应;用发光菌急性毒性实验评价了KTP降解过程中的毒性变化,发现KTP氧化过程中体系的毒性低于氧化前KTP的毒性,表明Fe^(2+)/PMS体系是一种有效降低KTP毒性的方法.

Ketoprofen （KTP） was chosen as the behavior in Fe2＋/potassium peroxy monosulfate target compound to investigate the degradation （PMS） oxidation process, pH effected the degradation of KTP by changing the form of KTP and Fe2＋ in Fe2＋/PMS. The results demonstrated that acidic condition increased the degradation of KTP. The highest KTP decomposition rate reached 66.8% when the pH was 3. SO4= and HO· were detected in the photolysis process using ethanol and tertiary butanol as the radical scavergers. Radical scavenging test revealed that SO4- played a primary role at acidic condition, while HO. was the main oxidizing specie at alkaline and neutral conditions, indicating that the increase of pH could lead to the transformation of free radical from SO4 to HO· ; HCO3 shows positive effect on the degradation of KTP in the concentration range from 0 to 0.01 mmol· L-1 , while negative effects from 0.01 to 10 mmol· L-1. HA demonstrates positive effect on the degradation of KTP in the concentration range from 0 to 10 mg· L-1, while negative effects from 10 to 50 mg· L-1. The degradation products of KTP were identified using UPLC/MS/ MS, and possible pathways were proposed by decarboxylic, hydroxylation and ketonized reactions. The toxicity of the degradation products was evaluated using the Microtox test, which demonstrated that the solution was less toxic than the reactants, which revealed that Fe2＋/PMS oxidation process was an effective method for reducing the toxici of KTP.