不同形态氮对水环境中氯贝酸光降解的影响

摘要

在模拟太阳光照射条件下,研究了不同浓度的NO3-、NO2-和NH4+对氯贝酸(Clofibric acid ,CA)在水环境中光降解的影响,并通过对光屏蔽系数的计算和对活性基团的淬灭实验对它们的影响机理进行了考察。通过模拟水体pE值变化,考察了无机氮离子对CA光降解的复合影响。结果表明,在NO3-、NO2-和NH4+存在时,CA的光降解均符合拟一级动力学方程。由于抑制·OH的产生,并与CA竞争吸收光子,NO2-和NO3-对CA的光降解均具有抑制作用,且NO3-对CA光降解的抑制作用强于NO2-,NH4+则对CA的光降解无明显影响。随着水环境中pE值的改变, CA的光降解速率也发生改变。 NO2-和NH4+、NO2-和NO3-同时存在均对CA光降解的影响具有拮抗作用,而且NO2-和NO3-之间的拮抗作用强于NO2-和NH4+之间的拮抗作用。%This study examined the influence of NO3-, NO2-, and NH4+ on the photodegradation of clofibric acid under the simulated sunlight in water. Their influence mechanisms were inspected by calculating light-screening factor and quenching experiments. The recombinational influence of inorganic nitrogen on the photodegradation of clofibric acid under various simulated pE values was also explored. Results showed that photodegradation of clofibric acid with the presence of NO3-, NO2-, and NH4+followed the pseudo-first-order kinetics. Both NO3- and NO2-inhibited the photodegradation of clofibric acid, while NH4+had no influence on clofibric acid removal. NO3-showed much stronger inhibitory effect than that of NO2-. Photodegradation conversion of clofibric acid changed with altering pE value. The co-existence of NH4+ and NO2-, or NO3-and NO2-in water displayed antagonism to influence on the photodegradation of clofibric acid. However, antagonism between NO3-and NO2-was stronger than that between NH4+ and NO2-.