| A large number of polybrominated diphenylethers(PBDEs) were used in furniture, electronics and computers in order to meet fire safety regulations.These compounds become increasingly important environmental pollutants since they have been detected frequently in sediments,sewage sludge,and atmosphere throughout the planet,and concern on the environmental safety of some PBDEs which have been detected in animal fat and human blood such as DPE and 4-BrDPE,has prompted people to pay more attention.The reaction between PBDEs and reactive radicals in the natrural environments may be very important to their transformation and removal process.However,few microscopic researches have investigated the kinetics and mechanisms of related chemical processes.In this paper,the photolysis reaction of C12H10O-HNO2-CH3CN-H2O and C12H9OBr-HNO2-CH3CN-H2O solution system were studied by the 355 nm laser flash photolysis-transient absorption spectra technique respectively,and other complementary analytical techniques such as GC-MS,LC-MS and UV-Vis were used to draw the related mechanisms.The dissertation is mainly composed of three parts:In part 1 the main characteristic peaks in the transient absorption spectra were attributed and the decay rate constants were investigated while photolyzing C12H10O-HNO2-CH3CN-H2O solution in the presence or absence of O2 by 355nm laser light.a.It was found that the OH radical obtained by the cleavage of nitrous acid could reacted with C12H10O to produce C12H10O-OH adduct,which had absorption peaks at 330 nm.b.The first order decay constant of C12H10O-OH adduct was measured to be(1.86±0.14)×105 s-1 in the absence of O2 and pseudo-first order decay constant was(6.6±0.4)×106 s-1 in the presence of O2,respectively.The final photolysis products were identified by GC-MS analysis to be phenol,o-hydroxyldiphenylether, p-hydroxyldiphenylether and p-nitrodiphenylether.In part 2 the microscopic reaction mechanism of 4-bromodiphenylether(4-BrDPE) with nitrous acid(HNO2) in the absence of O2 have been explored by the 355 nm laser flash photolysis technique.c.It was proposed that OH radical,could added to different phenyl rings of 4-BrDPE to forms 2 adducts,i.e.,4-BrDPE-OH adduct and 4-BrOH-DPE adduct.The first-order decay rate constants of 4-BrDPE-OH adduct and 4-BrOH-DPE adduct were measured to be(2.19±0.04)×105 s-1 and(1.56±0.03)×105 s-1,respectively.d.The absorption peaks of 4-BrDPE-OH adduct and 4-BrOH-DPE adduct were at 330 nm and 320 nm,respectively.e.The final photolysis product of 4-BrDPE and HNO2 identified by LC-MS analysis was mainly the dimeric compounds.Compared the different reaction processes of C12H10O-OH adduct and C12H9OBr-OH adduct.f.Benzene was added to CH3CN-H2O-C12H10O-HNO2 solution as OH scavenger to acquire the reaction rate constant of OH and C12H10O.The photolysis reaction initiated by 355nm laser light in the absence of O2 of CH3CN-H2O-C6-H6-C12H10O-HNO2 solution was studied by solving related kinetic equations and the reaction rate constant of OH and C12H10O was obtained to be(1.8±0.8)×1010 1·mol-1·s-1.The above research results provide imformation for the deeper understanding of the photo-induced conversions of PBDEs and further microscopic study of photolysis reactions of other PBDEs.
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