UV/MgO_(2)体系对水体中双酚A的降解机制研究

Mechanism study on the degradation of bisphenol A in water by UV/MgO_(2) system

双酚A(BPA)是一种典型的内分泌干扰物(EDCs),对人体和生物都存在毒性风险.高级氧化技术(AOPs)因其能产生大量的活性物种来降解污染物,成为目前处理环境中污染物最常用的方法之一.本研究采用紫外联合过氧化镁(UV/MgO_(2))体系降解水体中的BPA,并探究了该体系对BPA的降解机制.实验结果表明,UV/MgO_(2)体系能够高效降解水体中的BPA,在1 h内降解率可达98%,体系降解的反应速率对比单独MgO_(2)和单独UV降解分别提高了约48倍和18倍.数据显示在0.5 g·L^(-1)MgO_(2)浓度下BPA的降解速率最快.水体的pH、不同水体及水体中的不同离子对UV/MO_(2)体系降解BPA具有一定的影响作用(其中,SO_(4)^(2-)、HCO_(3)^(-)和HA有明显抑制作用),总体来说,体系的适应性较强.通过电子自旋共振(EPR)检测得知体系中存在·OH、^(1)O_(2)和O_(2)^(·-)3种自由基,其稳态浓度分别为6.475×10^(-14)、1.084×10^(-11)和4.605×10^(-9)mol·L^(-1),其中,O_(2)^(·-)为主导因子,贡献率约为90%.通过液相质谱(LC-MS/MS)对该体系降解BPA的产物进行了分析,初步推断出2条降解路径,主要是自由基攻击苯环的双键以及连接2个苯环的C—C键,使BPA得以降解.同时还对BPA的降解产物进行了毒性预测,结果表明,降解过程中BPA产物的生物毒性呈减小的趋势.本研究为UV/MgO_(2)技术的应用提供了理论依据.

Bisphenol A(BPA)is a typical endocrine disrupting chemicals(EDCs)that poses a toxic risk to both humans and organisms.Advanced oxidation process(AOPs)is one of the most commonly used methods to treat pollutants in the environment due to its great ability to generate large amounts of reactive oxygen species to degrade them.In this study,the UV/MgO_(2) system was used to degrade BPA in water,and the degradation mechanism of BPA by this system was investigated.The experimental results showed that the UV/MgO_(2) system could efficiently degrade BPA in water,and the degradation rate could reach 98%within 1 h.The degradation rate constant of the system increased about 48 times and 18 times compared with MgO_(2) and UV degradation alone.The data also showed that the degradation rate of BPA was the fastest at 0.5 g·L^(-1) MgO_(2) concentration.The pH values,different water bodies and different ions in the water column did certain influence on the degradation rate of BPA by the UV/MgO_(2) system(SO_(4)^(2-),HCO_(3)^(-)and HA had obvious inhibitory effects),indicating the adaptability of the system.The existence of·OH、^(1)O_(2) and O_(2)^(·-)in UV/MgO_(2) system were proved by EPR spectrum,and the steady-state concentrations were 6.475×10^(-14) mol·L^(-1),1.084×10^(-11) mol·L^(-1),and 4.605×10^(-9) mol·L^(-1),respectively.O_(2)^(·-) was the dominant factor,from which the contribution rate was~90%.The products of BPA degradation in this system were analyzed by LC-MS/MS,and two degradation pathways were initially deduced,mainly due to the attack of free radicals on the double bond of the benzene ring and the C—C bond connecting the two benzene rings,which allowed the degradation of BPA.The toxicity prediction of BPA degradation intermediates was also carried out,and the results showed that the biological toxicity of BPA products tended to decrease during the degradation process.This study provides a theoretical basis for the application of UV/MgO_(2) technology.