氯酚溶液的γ辐照还原降解研究

Reductive Degradation of Chlorophenols in Aqueous Solution by Gamma Irradiation

氯酚由于氯取代基产生的诱导效应,使其容易受到亲核粒子的攻击而被还原降解.通过测定γ辐照前后氯酚母体、Cl-离子以及反应中间产物的浓度变化,研究了4种氯酚水溶液(4-CP、2-CP、2,4-DCP、2,4,6-TCP)与水合电子ea-q反应的降解脱氯过程.结果表明,在水合电子ea-q还原体系中,4种氯酚的降解脱氯顺序依次为:2,4,6-TCP>2,4-DCP>2-CP>4-CP,多氯酚比单氯酚容易降解脱氯,邻位上的氯原子要比对位上的氯原子更容易去除,苯酚和Cl-是氯酚反应降解的最终产物.另外,4种氯酚的降解和脱氯过程皆遵循一级反应动力学特征,4-CP、2-CP、2,4-DCP和2,4,6-TCP的降解反应常数分别是0.154、0.253、0.750和1.188 kGy-1,脱氯反应常数分别为0.137、0.219、0.251和0.306 kGy-1.

Because chlorine is an electron withdrawing group,the highly chlorinated phenols may react quickly with hydrated electrons rather than with hydroxyl radicals.The process of reactions of four chlorophenols（4-CP,2-CP,2,4-DCP,2,4,6-TCP） with e-aq was investigated in aqueous solutions by detecting the concentration of CPs,Cl-and intermediates.In the e-aqreductive system,the experimental results showed that the order of four kinds of chlorophenol degradation and dechlorination was 2,4,6-TCP2,4-DCP2-CP4-CP.The greater the chlorine content was the higher reactivity of hydrated electrons towards chlorophenols was.Furthermore,hydrated electrons may preferentially attack the ortho-position of chlorine atom rather than the para-position of chlorine atom.Phenol and Cl-were detected as the final product of the reductive reaction.Additionally,processes of degradation and dechlorination of CPs were observed as the pseudo-first-order kinetics.The reaction constant of degradation of 4-CP,2-CP,2,4-DCP and 2,4,6-TCP were 0.154,0.253,0.750 and 1.188 kGy-1,respectively.Meanwhile,the dechlorination of 4-CP,2-CP,2,4-DCP and 2,4,6-TCP were 0.137,0.219,0.251 and 0.306 kGy-1,respectively.