利用瞬态吸收光谱技术研究水体中苯与亚硝酸的交叉反应机理

Study on the Cross-Reaction Mechanism of Aqueous Benzene with Nitrous Acid in Dilute Solutions by Transient Absorption Spectrum Technique

利用瞬态吸收光谱技术进行了有氧、无氧条件下苯与亚硝酸水溶液复相体系的交叉反应机理研究 ,初步考察了这些瞬态物种的生长与衰减等行为 ;并对其光解产物进行了GC/MS分析 .研究表明 ,HNO2 在 3 5 5nm紫外光的照射下可产生·OH和NO+ ,·OH自由基和苯反应生成C6H6 OHadduct ,反应速率常数为 8 9× 10 9L·mol-1·s-1,在有氧条件下C6H6 OHadduct进一步氧化为C6H6 OHO2 ,反应速率常数 3 3× 10 8L·mol-1·s-1;NO+ 自由基和苯作用形成C6H6 NO+ πcomplex 。

The cross-reaction microscopic mechanism of aqueous benzene with nitrous acid in the presence of O-2 or absence of O-2 in dilute solutions was studied by laser flash photolysis. The main characteristic peaks in these transient absorption spectra were attributed and the build-up/decay trends of several transient species were investigated. (.) OH radical and nitrosonium. cation (NO+) can be produced in aqueous solution of nitrous acid exposed to 355 nm laser beam. NO+ reacts with benzene to produce C6H6-NO+ pi complex. The rate constant of the reaction between (.) OH radical and benzene was measured to be 8.9 x 10(9) L (.) mol(-1) (.) s(-1). The transient product C6H6-OH adduct reacts with O-2 to form C6H6-OHO2 with the rate constant of 3.3 x 10(8) L (.) mol(-1) (.) s(-1). The final photolysis products were analyzed by using GUMS method and the possible reaction pathways were also discussed.