双酚A在河口水中的光解动力学

为研究双酚A（BPA）在河口水中的光解动力学及水中重要溶解性组分对其光解的影响，在广西钦州大榄江连接茅尾海的河口水域采取水样，通过模拟日光实验研究了河口水中BPA的光解动力学，及河口水中的重要溶解性组分Cl^-，Br^-，溶解性有机质（DOM），NO₃^-和HCO₃^-对BPA光解的影响.结果表明，河口水中BPA的光解速率常数k值比纯水中大，且上游水样中BPA的k值是下游水样的2.5倍.稳态光解实验表明DOM及其与卤素离子作用显著影响BPA的光解，虽然NO₃^-也影响BPA光解，但与DOM共存时，NO₃^-的影响不明显.自由基淬灭和竞争反应动力学实验发现激发三重态DOM（³DOM^*）和卤素自由基（HRS）是决定河口水样中BPA光降解的主要活性物种，且³DOM^*与BPA的反应活性（二级反应速率常数k_3DOM*，BPA=4.42×10⁸L/（mol·s）要高于HRS与BPA的反应活性（k_BPA，Cl·=2.11×10⁸L/（mol·s），k_BPA，Cl2·-=8.5×10⁶L/（mol·s）.下游水样中高含量的卤素离子（292mmol/L）易淬灭³DOM^*产生反应活性较低的HRS，致使下游水体中BPA的光解速率低于上游水体.

Photodegradation kinetics of bisphenol A in estuarine water

To study the photodegradation kinetics of bisphenol A (BPA) and the photolysis effect of the main water components in estuarine water, the real water sample was collected in the estuarine waters connecting the Maowei Sea and the Dalan River in Qinzhou city, China. The photodegradation kinetics of BPA in estuarine water sample and the effects of Cl^-, Br^-, dissolved organic matter (DOM), NO₃^-, HCO₃^-, and ionic strength on the photolysis of BPA were studied by simulated sunlight experiment. The results showed that the photolysis rate constant (k) value of BPA in estuarine water was higher than that in pure water, and the k value of BPA in the upstream water sample was 2.5 times as compared to the downstream water sample. Steady-state photolysis experiments showed that DOM and its interaction with halogen ions significantly affect the photolysis of BPA. Although NO₃^- also affected the photodegradation kinetics of BPA, the effect of NO₃^- was not obvious when it was concomitant with DOM. Radical quenching and competitive reaction kinetics experiments found that the triplet-excited state DOM (³DOM*) and halogen radicals (HRS) are the main reactive species that dominate the photodegradation of BPA in estuarine water samples. Moreover, the reactivity of ³DOM* with BPA (second-order reaction rate constant, k_3DOM*,BPA=4.42×10⁸L/(mol·s) was higher than that of HRS with BPA (k_BPA,Cl·=2.11×10⁸L/(mol·s),k_BPA,Cl2·-=8.5×10⁶L/(mol·s). The relatively high concentrations of halide ions (292mmol/L) in downstream water samples can easily quench ³DOM* to generate HRS with relatively low reactivity towards BPA,which can explain the phenomenon that the photolysis rate constant of BPA in the downstream water sample was lower than that of the upstream water sample.