Cu2+强化UV活化过氧乙酸降解水中的双氯芬酸

研究了Cu²⁺强化UV活化过氧乙酸（Cu²⁺/UV/PAA）对水中双氯芬酸（DCF）的降解，考察了pH值、PAA投加量、Cu²⁺投加量、无机阴离子（Cl^-、SO₄^2-、NO₃^-和CO₃^2-）和溶解有机物（DOM）对DCF去除的影响；探讨了DCF在该体系中的降解产物和转化机理.结果表明：UV和Cu²⁺都能活化PAA产生活性自由基促进DCF降解.DCF在Cu²⁺/UV/PAA中的降解遵循准一级动力学，其降解可能归因于直接光解、HO^·氧化和CH₃COO^·、CH₃COOO^·等其它自由基氧化.在pH=3~11范围内，DCF降解的最佳pH=8.5.DCF的降解效率随着PAA投加量的增大而逐渐增高，过量的PAA能与DCF竞争HO^·.Cu²⁺用量的提高也能促进DCF的去除，但是过量的Cu²⁺可生成Cu（OH）₂导致其催化能力下降.由于NO₃^-在UV照射下可以产生HO^·，其对DCF降解有促进作用，且NO₃^-浓度越高，促进作用越明显.不同浓度的Cl^-、SO₄^2-、CO₃^2-和DOM对DCF降解影响较小.在Cu²⁺/UV/PAA降解DCF的过程中，共检测出13种降解产物.根据这些降解产物，提出了DCF可能的转化机理，包括8种不同的反应路径.

Degradation of diclofenac in water by Cu2+ enhanced UV activation of peracetic acid

The degradation of diclofenac (DCF) by Cu²⁺ enhanced UV activation of peracetic acid (Cu²⁺/UV/PAA) was investigated. The effects of pH, PAA dose, Cu²⁺ dose, inorganic anions (such as Cl^-, SO₄^2-, NO₃^- and CO₃^2-) and dissolved organic matter (DOM) on DCF removal by Cu²⁺/UV/PAA were also evaluated. The degradation products and transformation mechanism of DCF by Cu²⁺/UV/PAA were studied. Both UV and Cu²⁺ could activate PAA to produce active radicals, which could promote DCF removal. The degradation of DCF by Cu²⁺/UV/PAA followed the pseudo first-order kinetics and its degradation was probably attributed to direct photolysis, HO^· oxidation and other radicals oxidation such as CH₃COO^· and CH₃COOO^·. In the pH range of 3-11, DCF had the best degradation efficiency at pH 8.5. When PAA dose increased, the degradation efficiency of DCF was enhanced gradually, but excessive PAA could compete with DCF for HO^·. The increase of Cu²⁺ dose could also promote DCF removal, while excessive Cu²⁺ could form Cu(OH)₂, which might lead to the reduction of its catalytic ability. Since NO₃^- can generate HO^· under UV irradiation, its existence promoted the degradation of DCF, and the enhancement effect increased with the increase in its concentration. The presence of Cl^-, SO₄^2-, CO₃^2- and DOM in different concentrations had little effect on DCF removal. Thirteen degradation products were detected in the degradation of DCF by Cu²⁺/UV/PAA. According to these degradation products, the probable transformation mechanism of DCF was proposed exhibiting eight reaction pathways.