水中无机氮形态变化对酮洛芬光降解的影响

研究了模拟太阳光照射下水环境中不同形态氮(NO₃^-、NO₂^-和NH₄⁺)对酮洛芬(KET)光解的影响.结果表明,KET在平均波长(200~450nm)下量子产率Φ_o为0.14. NO₃^-浓度从0.01mmol/L^-增至1.0mmol/L时, KET光解速率常数从0.0109降至0.0085; NO₂^-浓度从0.01mmol/L增至1.0mmol/L时, KET光解速率常数从0.0095降至0.0069, NH₄⁺对KET的光解基本无影响. NO₃^-的光掩蔽现象对KET光解的影响起主要作用; NO₂^-则通过光掩蔽现象和羟基自由基猝灭来抑制KET的光解.同时研究了当水环境中pE值发生变化而引起水中无机氮形态转化时,不同形态氮共存对KET光解的复合影响,随着pE值的增大,KET的光解速率先减小后增大;当NO₂^-和NH₄⁺共存时,两者对KET光解的影响存在拮抗作用,这一拮抗作用也存在于NO₂^-和NO₃^-之间.

Photodegradation of ketoprofen in aquatic environment: Effect of different forms of nitrogen

The impacts of different nitrogen forms (NO₃^-, NO₂^- and NH₄⁺) on the photodegradation of KET were investigated under Xe lamp irradiation. The direct photolysis solar quantum yield of KET was observed to be 0.14. Increasing the concentration of NO₃^- from 0.01mmol/L to 1.0mmol/L, the apparent rate constants of KET were decreased from 0.0109 to 0.0085. The apparent rate constants of KET decreased from 0.0095 to 0.0069when the concentration of NO₂^- increased from 0.01mmol/L to 1.0mmol/L. NH₄⁺ had no influence on KET photolysis. The screening effect of NO₃^- was the major factor on KET photolysis while NO₂^- inhibited photolysis via both attenuating light and quenching ×OH. Photodegradation of KET was also investigated under different pE values. The photodegradation rate of KET decreased at first, then it increased with the increasing pE values. The antagonistic effect existed on the photodegradation of KET when NO₂^- coexisted with NH₄⁺. And it also existed when NO₂^- coexisted with NO₃^- on the photodegradation of KET.