低温等离子体对水体中4-氯酚的脱氯

Dechlorination of 4-Chlorophenol in Aqueous Solution Using Low-temperature Plasma

利用平板双介质阻挡放电研究了富氧条件下水相中的4 氯酚的脱氯机理.结果表明,4 氯酚在等离子体的作用下能有效脱氯,而其CODCr下降相对缓慢;4 氯酚的脱氯过程在不同初始浓度和溶液初始pH值下均较好地符合一级反应;4 氯酚的脱氯速率常数与其初始浓度C0和初始pH值的关系分别近似为:k(C0)=0.326+0.678EXP( C0/48)和k(pH)=0.231+0.0452EXP(pH/3.53);pH值降低不利于4 氯酚的脱氯;等离子体降解4 氯酚主要是电子轰击水产生的水相活性粒子的作用,其中起主要作用的是OH·自由基和水合电子eaq ;气相中的活性物种对脱氯率的影响不大,但对CODCr的下降影响较大.

Dechlorination mechanism of 4-chlorophenol in aqueous solution in plasma has been studied by means of flat dielectric barrier discharge(DBD) in oxygen. The results show that 4-chlorophenol can be effectively dechlorinated when treated by DBD-plasma, but the elimination rate of COD_(Cr) is relatively slower. Functional dependence of dechlorination rate constants(k) of 4-chlorophenol upon its initial concentration and solution initial pH value are respectively: k_((C_0))=0.326+0.678 EXP (-C_0/48) and k_((pH))=0.231+0.0452 EXP (pH/3.53). The dechlorination of 4-chlorophenol is retained when pH value goes down. 4-chlorophenol is dechlorinated primarily by the reactive species, specifically OH·and e_(aq)^-, generated by the electron bombardment on water molecules. Reactive species in gas phase show no appreciable influence on the dechlorination of 4-chlorophenol, but they can affect the COD_(Cr) elimination rate.