UV/H_2O_2氧化降解克拉霉素的反应动力学及影响因素

Degradation of clarithromycin by UV/H_2O_2 process:reaction kinetics and impact factors

克拉霉素用量大、检出频率高、生态风险大,已被欧盟列为优先监测污染物.针对传统污水处理厂难以完全去除克拉霉素的问题,主要研究了UV/H_2O_2降解克拉霉素的效果和反应动力学,探讨了pH、天然有机质(NOM)和水中共存阴、阳离子对UV/H_2O_2降解克拉霉素的影响.结果表明:单一UV对克拉霉素的光降解符合准一级反应动力学模型,其反应速率常数为0.0016 min^(-1).UV/H_2O_2对克拉霉素的降解符合准一级反应动力学模型,且克拉霉素的降解速率随H_2O_2浓度的增大而增大,在H_2O_2浓度为40 mmol·L^(-1)时,克拉霉素降解的反应速率常数为0.0284min^(-1).克拉霉素与·OH的二级反应速率常数为(2.36±0.20)×10^(10)L·mol^(-1)·s^(-1).碱性条件有利于克拉霉素的降解;NOM(2~10 mg·L^(-1))会抑制克拉霉素的降解,且随NOM浓度增大而增大;共存阴离子CO_3^(2-)对克拉霉素降解无影响,HCO_3^-、NO_3^-、Cl^-会抑制克拉霉素的降解,抑制程度的大小顺序为NO_3^->HCO_3^->Cl^-;共存阳离子Ca^(2+)、Mg2+、Cu^(2+)、Fe^(3+)会抑制克拉霉素的降解,抑制程度的大小顺序为Fe^(3+)>Cu^(2+)>Mg2+>Ca^(2+).

European Union （EU） has listed etarithromycin （CLA） in the priority pollutants due to its high usage, frequently detection in environment and high ecosystem risk. As conventional wastewater treatment plant cannot remove CLA completely, the degradation efficiency and reaction kinetics of CLA by UV/H2O2 were studied, the effects of pH, natural organic matter （NOM） , cations and anions on the degradation of CLA were also investigated. The results show that the degradation of CLA by UV follows pseudo-first-order kinetics, and the reaction rate constant was 0.0016 min-1. The degradation of CLA by UV/H2O2 also follows pseudo-first-order kinetics, and the removal efficiency increased with the H2O2 concentration. The degradation rate constant of CLA can reach up to 0.0284 min-1 with H2O2 concentration of 40 mmol·L-1. The second reaction rate constant between CLA and .OH was （2.36±0.20） ℃ 1010L· mo1-1·s-1. alkalinie pH is favorable for the degradation of CLA. The presence of NOM （ 2 -10 mg·L-1 ） inhibited the degradation of CLA, and the inhibition effect is enhanced with the increasing of NOM concentration. Anion COl- showed no effect on the degradation of CLA, while HCOx, NOx and Cl- inhibited the degradation of CLA following the order of NO3 〉HCO3 〉Cl-. Cation Ca2＋, Mg2＋, Cu2＋ and Fe3＋ inhibited the degradation of CLA in the order of Fe3＋ 〉Cu2＋ 〉Mg2＋ 〉Ca2＋.