2,4,6-三氯酚的UV/H_2O_2光化学降解

UV/H_2O_2 photochemical degradation of 2,4,6-trichlorophenol

采用UV/H2O2工艺降解水中2,4,6-三氯酚(2,4,6-TCP),研究H2O2投加量、pH、阴离子、阳离子、叔丁醇和腐殖酸对降解效果的影响,并利用LC-HESI-MS-MS探讨UV/H2O2降解2,4,6-TCP的降解机理。研究结果表明:UV/H2O2降解2,4,6-TCP的过程符合拟一级反应动力学。随着H2O2投加量的增加,2,4,6-TCP的去除率和反应速率增加,当H2O2投加量为10mmol/L时,反应速率常数K达到0.1094min-1。酸性条件更利于UV/H2O2降解2,4,6-TCP。水中各种离子的存在对2,4,6-TCP的光解速率有较大的影响,其中阴离子CO32-对反应均存在明显的抑制作用,阳离子Fe3+促进效果显著。2,4,6-TCP的UV/H2O2反应速率随叔丁醇浓度的增加而下降,腐殖酸在低浓度时促进反应进行,在高浓度时,2,4,6-TCP的降解受到抑制。水中2,4,6-三氯酚在UV/H2O2作用下主要发生脱氯反应,生成二氯邻二苯酚或二氯对二苯酚,未得到彻底矿化。

The degradation of 2,4,6-trichlorophenol（2,4,6-TCP）by UV/H2O2 in aqueous solutions was investigated.The effects of H2O2 dosage,pH,cations,anions,tert-butanol and humic acid on the removal of 2,4,6-TCP were evaluated and the mechanism for oxidation of 2,4,6-TCP by UV/H2O2 was analyzed by using LC-HESI-MS-MS.The results indicate that the UV-H2O2 degradation of 2,4,6-TCP well follows pseudo first order kinetics.The removal of 2,4,6-TCP and reaction rate can be enhanced by increasing H2O2 dosage.When the dosage of H2O2 is 10 mmol/L,the reaction rate constant K reaches 0.109 4 min -1 .The pH value of the solution greatly influences the 2,4,6-TCP degradation and the degradation performs well in acid condition.Irons in water have a significant influence on the 2,4,6-TCP degradation by UV/H2O2.CO3 2-inhibits the 2,4,6-TCP degradation significantly,however,Fe 3＋exhibits an obvious promoting effects on 2,4,6-TCP degradation.A majority of 2,4,6-TCP transforms into dichlorocatechol or dichlorohydroquinone without complete mineralization.