二溴一氯硝基甲烷在紫外光照下的降解规律及反应路径

Degradation law and reaction path of dibromochloronitromethane under UV irradiation

为探究二溴一氯硝基甲烷(DBCNM)在紫外光照下的降解规律,采用低压汞灯UV_(254)考察了光照强度、初始浓度、pH值、自由氯浓度和溴离子浓度对DBCNM光降解的影响.实验结果表明:DBCNM在紫外光照(15.5 mW/cm^(2))条件下的降解符合一级反应动力学规律,其降解速率常数为0.3039 min^(-1);DBCNM的光降解率随初始浓度的增加而降低,随光照强度、pH值、自由氯浓度和溴离子浓度的增加而升高;紫外光照下自由氯和溴离子的添加促使DBCNM转化成其他卤代硝基甲烷(HNMs);在形成的其他HNMs中,一溴硝基甲烷(BNM)和一溴二氯硝基甲烷(BDCNM)贡献的细胞毒性较大,BNM、BDCNM和一溴一氯硝基甲烷(BCNM)贡献的遗传毒性较大;最终,DBCNM经过氧化、加成和水解反应转化为无机离子,降低了水质安全风险.

To explore the degradation law of dibromochloronitromethane(DBCNM)under ultraviolet(UV)irradiation,the effects of light intensity,initial concentration,pH value,free chlorine concentration,and bromide ion concentration on the photodegradation of DBCNM were studied by using a low-pressure mercury lamp UV254.Experimental results show that the photodegradation of DBCNM under UV irradiation(15.5 mW/cm^(2))fits the first-order reaction kinetics model,and its degradation rate constant is 0.3039 min_(-1).The photodegradation rate of DBCNM decreases with the increase of initial concentration,and increases with the increase of light intensity,pH value,free chlorine concentration and bromide ion concentration.The additions of free chlorine and bromide ion promote the conversion of DBCNM into other halonitromethanes(HNMs)under UV irradiation.In other formed HNMs,bromonitromethane(BNM)and bromodichloronitromethane(BDCNM)contribute more cytotoxicity,while BNM,BDCNM and bromochloronitromethane(BCNM)contribute more genotoxicity.Finally,DBCNM is converted into inorganic ions through oxidation,addition and hydrolysis reactions,reducing the risk of water safety.