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Gong P.,Fudan University | Yuan H.,Fudan University | Yuan H.,Institutes of Naval Medicine | Zhai P.,Fudan University | And 4 more authors.
Chemical Engineering Journal | Year: 2015

Benzophenone-3 (BP-3), an organic ultraviolet (UV) filter, is reported to exhibit endocrine disruptive effects. In this study, the degradation of BP-3 by UV/H2O2 in aqueous solution was investigated by steady-state photolysis and laser flash photolysis experiments. The photolysis of BP-3 was not observed obviously after 8h under UV irradiation (λ=254nm), but the degradation of BP-3 could be conducted via UV/H2O2 due to the oxidation by hydroxyl radical (HO). At higher initial concentrations of BP-3, the degradation percentages decreased, and the optimal pH for the degradation of BP-3 was 6.0. The reaction of BP-3 and HO adhered to the pseudo-first-order kinetics. When the BP-3 concentration was 0.01mM, the rate constants of the apparent first-order reaction and second-order reaction between BP-3 and HO were 1.26×10-3s-1 and 2.97×1010M-1s-1, respectively. Several intermediate products were obtained and the primary reaction pathway of BP-3 and HO was proposed. © 2015 Elsevier B.V. Source

Yuan H.,Fudan University | Yuan H.,Institutes of Naval Medicine | Pan H.,Institutes of Naval Medicine | Shi J.,Fudan University | And 2 more authors.
Frontiers of Environmental Science and Engineering | Year: 2015

The reactions between chlorinated benzenes (CBzs) and hydrated electron (eaq −) were investigated by the electron beam (EB) and laser flash photolysis (LFP) experiments. Under the EB irradiation, the effects of irradiation dose, initial concentration and the number of Cl atoms on the removal efficiencies were further examined. At 10 kGy, the removal efficiencies of mono-CB, 1,3-diCB, 1,2-diCB and 1,4-diCB were 41.2%, 87.2%, 84.0%, and 84.1%, respectively. While irradiation dose was 50 kGy, the removal efficiencies increased to 47.4%, 95.8%, 95.0%, and 95.2%, respectively. Irradiation of CBzs solutions has shown that the higher the initial concentration, the lower the percentage of CBzs removal. In addition to this, the dechlorination efficiencies of 1,2-dichlorobenzene (1,2-diCB), 1,3-dichlorobenzene (1,3-diCB) and 1,4-dichlorobenzene (1,4-diCB) were much higher than that of chlorobenzene (mono-CB). The kinetics of the reactions was achieved with nanosecond LFP. The rate constants of second-order reaction between eaq − with mono-CB, 1,2-diCB, 1,3-diCB and 1,4-diCB were (5.3±0.4) × 108, (4.76±0.1) × 109, (1.01±0.1) × 1010 and (3.29±0.2) × 109 L·mol−1·s−1, respectively. Density functional theory (DFT) calculations were performed to determine the optical properties of unstable CBzs anion radicals, and the main absorption peaks lied in the range of 300–550 nm. The primary reaction pathway of CBzs with eaq − was gradual dechlorination, and the major products were Cl− and benzene (CBzs(-Cl−)). Furthermore, biphenyl (or chlorobiphenyl) was observed during the LFP, which was probably formed by recombination of benzene radicals. © 2014, Higher Education Press and Springer-Verlag Berlin Heidelberg. Source

Yuan H.,Fudan University | Yuan H.,Institutes of Naval Medicine | Pan H.,Institutes of Naval Medicine | Shi J.,Fudan University | And 2 more authors.
Asian Journal of Chemistry | Year: 2014

The nanosecond laser flash photolysis (LFP) experiments were adopted to investigate the kinetics and mechanisms of the reaction between bromobenzene and hydrated electrons (eaq) in aqueous solution. The results showed that the rate constants of first-order and second-order reaction were 6.3 × 105 s-1 and 1.7 × 1010 L mol -1 s-1, respectively. The final products were biphenyl, bromobiphenyl and Br-, which determined by gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC). The optimal structure of bromobenzene anion radicals, the bond lengths and bond angles were calculated and analyzed by time-dependent density functional theory (TD-DFT)- UB3LYP method and the primary absorption peaks of the anion radicals lied in the ranges of 250-600 nm. The main reaction pathway was speculated that bromobenzene molecules generated unstable anion radicals when attacked by hydrated electrons and then the molecules debrominated to generate benzene radicals and Br-. Source

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