常温下过硫酸盐氧化降解水中对氯苯胺

Oxidation degradation of p-chloroaniline in water by persulphate at ambient temperatures

研究了常温下初始pH值对过硫酸盐氧化降解水中对氯苯胺(PCA)动力学过程的影响,并探讨了PCA降解的机理.结果表明,室温下,PCA的降解符合准一级动力学方程;pH值为3、5、7、9和11时,其一级动力学常数k分别为0.03×10-4、0.12×10-4、0.28×10-4、0.26×10-4和0.27×10-4s-1;酸性体系不利于PCA的降解,pH 7时PCA的降解速率最大,半衰期为6.88 h.通过LC/MS和GC/MS鉴定得到PCA降解的4种主要中间产物,分别为对氯硝基苯、对苯醌、1-(4氯苯)-3苯基脲和5-氯-2-(4氯苯二氮烯)苯酚,并在此基础上探讨了过硫酸盐氧化降解PCA的可能途径.

Effect of pH on the degradation kinetics of p-chloroaniline （PCA） by persulp.hate in aqueous solutions was investigated at ambient temperature. Intermediate products of the oxidation process were characterized using LC/MS and GC/MS techniques. The PCA degradation was found to follow a pseudo-first-order decay model. At 20 °C, [Na2S208]0 =2.50 mmol. L-1, [PCA]0 =0.05 mmol. L-1, the pseudo-first-order rate constants of PCA degradation by persulphate were 0. 03 x 10-4, 0. 12 x 10-4, 0. 28 x10-4, 0. 26 x 10-4 and 0. 27 x 10-4 s-1 at pH 3, 5, 7, 9 and 11, respectively. The maximum PCA degradation occurred at pH 7. 4-chloronitrobenzene, 1 - （ 4-chlorophenyl） -3 -phenylurea, 5 -chloro-2- （ （ 4-chlorophenyl ） diazenyl ） phenol and p-benzoquinone were identified as the major intermediates of PCA oxidation by persulphate. Tentative pathway for the degradation of PCA was proposed. The degradation of PCA in groundwater and buffer solution by persulphate was also tested.