355nm光诱发的水体中HNO_2与C_6H_5Br交叉反应机理  

Cross-Reaction Mechanism between HNO_2 and C_6H_5Br in Aqueous Solution under Irradiation at 355 nm

作　　者：秦艳[1,2] 黄丽[1] 董文博[1] 房豪杰[1] 侯惠奇[1] 

机构地区：[1]复旦大学环境科学研究所 [2]东华大学环境科学与工程学院,上海200051

出　　处：《物理化学学报》2007年第11期1677-1682,共6页Acta Physico-Chimica Sinica

摘　　要：利用激光闪光光解技术研究了有氧、无氧条件下HNO_2-C_6H_5Br-H_2O体系的光化学反应.研究结果表明,HNO_2与C_6H_5Br的光化学反应由HNO_2光解产生·OH自由基引发,·OH与C_6H_5Br反应生成C_6H_5Br…OH,反应速率常数为(8.1±0.7)×10~9 L·mol^(-1)·s^(-1).C_6H_5Br…OH可被HNO_2或O_2氧化.C_6H_5Br…OH与HNO_2的二级反应速率常数为(3.0±0.5)×10~7 L·mol^(-1)·s^(-1),比C_6H_5Br…OH与O_2的反应速率常数(4.0±0.6)×10~8 L·mol^(-1)·s^(-1)小,C_6H_5Br…OH与O_2生成的C_6H_5Br…OHO_2以(2.4±0.1)×10~4s^(-1)的速率单分子衰减.气相色谱.质谱联用(GC-MS)分析表明,C_6H_5Br…OH与HNO_2或O_2作用可形成多种含硝基的化合物或醌类物质.The reaction mechanism between HNO2 and C6H5Br in aqueous solution in the presence or absence of O2 was studied using laser flash photolysis transient absorption spectrum technique under irradiation at 355 nm. The experimental results suggested the generation of · OH radical through the photolysis of HNO2. The addition of · OH radical to bromobenzene to form an OH-adduct, C6H5Br…OH, involved a second-order rate constant of （8.1±0.7）× 10^9 L.mol^-1. s^-1 C6H5Br-OH could be oxidized by O2 or HNO2. The second-order rate constant （3.0±0.5）×10^7 L.mol^-1. s^-1 for the reaction of C6H5Br…OH with HNO2 was much slower than （4.0±0.6）×10^8 L.mol^-1. s^-1 for the reaction of C6H5Br…OH with O2, The decay constant of C6H5Br…OHO2 produced by the reaction of C6H5Br…OH with O2 decayed was （2.4±0.1）×10^4 s^-1. Gas chromatography and mass spectrometric （GC-MS） analysis suggested the formation of multiple compounds containing nitryl or quinone formed by the reaction of C6H5Br…OH with HNO2 or O2.

关 键 词：溴苯 激光闪光光解 HNO2 瞬态吸收光谱 ·OH自由基 交叉反应 

分 类 号：X52[环境科学与工程—环境工程]