溶液中阴离子对UV/H_2O_2降解十二烷基苯磺酸钠的影响及其机理

Effects of anions on UV/H_2O_2 oxidation of linear alkyl benzene sulfonate

研究了UV/H2O2工艺对十二烷基苯磺酸钠(LAS)的去除效果、溶液中阴离子对LAS降解的影响及机理。结果表明:UV/H2O2工艺可以有效地去除水中的LAS;在H2O2投加量为8mg/L,14W低压汞灯照射下,LAS在蒸馏水和自来水中的反应速率常数分别为0.0180、0.0122min-1;NO3-、Cl-、SO24-和HCO3-对LAS光降解有抑制作用,当该4种离子摩尔浓度均分别为5、10、15mmol/L时,对LAS光降解的抑制程度为HCO3->NO3->Cl->SO24-,且随着离子摩尔浓度的增大,抑制作用增强;LAS在自来水中的反应速率常数低于在蒸馏水中的反应速率常数是由于水中多种离子影响的结果。

Experiments were carried out to determine the effects of anions on UV promoted H2O2 oxidation of linear alkyl benzene s ulfonate （LAS）. The UV/H2O2 oxidation was capable of removing LAS. With an initial H2O2 concentration of 8 mg/L and a 14 W low pressure mercury vapor discharge lamp, the first order rate constants for photodegradation of LAS in distilled water and tap water were 0. 018 0 min^-1 and 0. 012 2 min^-1 , respectively. The presence of NO3^- ,Cl^- , SO4^2- and HCO3^- inhibited the LAS photodegradation. Within the concentration range studied （5-15 retool/L）, the order of inhibitory effect was HCO^3-〉NO3^- 〉Cl^- 〉SO4^2-. The degree of inhibition went up with higher concentrations of the anions. The inhibitory effects of anions in the tap water were responsible for the lower first order rate constant for photodegradation of LAS in tap water relative to that found in distilled water.