双氯芬酸钠水溶液的辐照降解

IRRADIATION INDUCED DEGRADATION OF DICLOFENAC IN AQUEOUS SOLUTION

利用60Coγ射线辐照双氯芬酸钠水溶液,探讨了不同辐照剂量下初始浓度、自由基促进剂和淬灭剂、水体共存物质等因素对降解的影响,研究其降解途径,并和等离子体放电降解效果进行了对比.结果表明,γ辐照可有效降解双氯芬酸钠,但矿化过程要长于降解过程,当初始浓度为20.5、30.4和50.1 mg·L-1时,反应动力学常数分别为2.55、2.12和1.90 kGy-1,呈现下降趋势,自由基促进剂和淬灭剂的影响结果说明该降解反应主要通过羟基自由基(.OH)、水合电子(ea-q)和氢原子(H.)等活性基团与目标分子反应实现,水体中常见的共存物质如硝酸根和腐殖酸对降解不会造成影响,降解途径主要是通过.OH的氧化作用和ea-q与H.的还原作用实现的.

60Co γ-ray irradiation-induced degradation of diclofenac and effect of degradation paraments such as initial diclofenal concentration,radical promoters,radical scavengers,and coexisting substances in natural waters were investigated.Furthermore,the degradation results were evaluated in comparison with the results by dielectric barrier discharge,and the corresponding transformation pathways were proposed.The results showed when the initial concentration of diclofenac was 20.5,30.4 and 50.1 mg·L-1,the kinetics constant was 2.55,2.12 and 1.90 kGy-1.The results obtained with the additon of H2O2,CH3OH and thiourea suggest that degradation of diclofenac could take place via two pathways： oxidation by ·OH radicals and reduction by e-aq and H·.The commonly coexisting substances in natural waters,such as humic acid and NO-3,did not affect the degradation efficiency.Based on the intermediates identification,the transformation pathways were proposed to be initiated mainly by H·,e-aq and ·OH.