Synthesis of Cu-2(OH)(3)Cl as facile and effective Fenton catalysts for mineralizing aromatic contaminants: Combination of sigma-Cu-ligand and self-redox property

Cu-2(OH)(3)Cl was synthesized as catalysts for mineralizing aromatic organics via Fenton reactions. Both Cu+ and Cu2+ are present in gamma-Cu-2(OH)(3)Cl, alpha-Cu-2(OH)(3)Cl and CuOHCl. Among them, gamma-Cu-2(OH)(3)Cl with the highest Cu+ percentage is the most active. Under relatively mild conditions, 88.7 % phenol, more than 85 % bisphenol A, benzoic acid, 2-chlorophenol and salicylic acid and around 79 % aniline are mineralized at their ambient pH. Compared to the reference catalysts CuSO4, CuO and Cu2O, gamma-Cu-2(OH)(3)Cl shows better mineralization ability, HO center dot production and H2O2 utilization efficiency. Cu2+ can form sigma-Cu-ligand complexes with phenolic hydroxyls in contaminants. Such complexes are readily attacked by H2O2, causing the electron transfer from aromatic rings to Cu2+ and the formation of HO center dot. Moreover, gamma-Cu-2(OH)(3)Cl shows self-redox property when induced by H2O2, initiating the electron transfer from H2O2 to Cu2+ and thus reducing Cu2+ into Cu+. These effects could accelerate Cu+ regeneration and improve H2O2 utilization efficiency.