Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (09): 1112-1117.doi: 10.3866/PKU.WHXB20040911

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Reaction Mechanism of Aqueous Benzene with Hydrogen Peroxide by Transient Absorbance Spectra

Zhu Cheng-Zhu;Zhang Ren-Xi;Zheng Guang-Ming;Ouyang Bin;Zhao Qing-Xiang;Hou Hui-Qi   

  1. Institute of Environmental Science, Fudan University, Shanghai 200433; College of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237
  • Received:2004-02-02 Revised:2004-05-10 Published:2004-09-15
  • Contact: Hou Hui-Qi

Abstract: The cross-reaction microscopic mechanism of aqueous benzene with hydrogen peroxide under different conditions was studied by laser flash photolysis. The main characteristic peaks in these transient absorbance spectra were assigned and the build-up/decay trends of several transient species were investigated. •OH radical can be produced in aqueous solution of hydrogen peroxide exposed to 266 nm laser beam. The reaction of •OH radical and benzene produces C6H6-OH adduct with a rate constant of (8.0~8.1)×109 L•mol-1•s-1 in the approximately neutral(pH≈6) and 7.7×109 L•mol-1•s-1 in acid (pH=1.5)solution, while the rate constant is about (6.7~6.9)×109 L•mol-1•s-1 in the basic (pH=9)solution. The C6H6-OH adduct will be able to react with O2 to form C6H6-OHO2, and then decompose into p-benzoquinone. In the meantime, C6H6-OH adducts and excited state of benzene may also react with H2O2 to form p-benzoquinone. The three reaction pathways were concurrently happened.

Key words: Laser flash photolysis, Benzene, Hydrogen peroxide, Transient absorption spectra, •, OH radical