Activation of hydrogen peroxide in copper(II)/amino acid/H2O2 systems: effects of pH and copper speciation

作者：Lin TY; Wu CH^*

来源：Journal of Catalysis, 2005, 232(1): 117-126.

DOI：10.1016/j.jcat.2005.01.038

• copper complex
• OH radical
• amino acid
• hydrogen peroxide
• quinaldine blue

Activation of hydrogen peroxide by different Cu(II)-amino acid complexes is performed and compared, with quinaldine blue as an oxidation indicator. Parameters such as pH and concentrations Of Cu(II), hydrogen peroxide, and amino acids (L = glycine, alanine, and lysine) are examined to understand the activation mechanism of hydrogen peroxide. The experimental rate law determined is first order in Cu(II)-amino acid complexes and variable order in hydrogen peroxide, by Michaelis-Menten kinetics. It indicates that the formation of ligand-Cu(II)-peroxide complex may be responsible for the activation of hydrogen peroxide. The oxidation rate is also substantially enhanced in Cu(II)/amino acid/H2O2 systems with increasing pH from 6 to 9. The trend is consistent with the formation of hydroxyl radical ((OH)-O-•), whose formation is favored in alkaline solutions. A mechanistic pathway that includes the formation of ligand-Cu(II)-peroxide complex and (OH)-O-• is proposed. For glycine, alanine, and lysine, the maximum activation efficiencies appear at a ligand/copper molar ratio of 1.5-2.0, regardless of the change in pH values or ligand concentrations. According to the stability constants for Cu(II)-amino acid complexes, it is predicted that CuL and not CuL2 is the dominant species forming the active copper complex catalyst. © 2005 Elsevier Inc.

• 出版日期2005-5-15
• 单位清华大学