Synthesis of γ-Cu 2 (OH) 3 Cl/LDH composites as Fenton catalysts to mineralize aniline: successive mineralization by hydroxyl and superoxide radicals

A series of composites were synthesized through in situ fabrication of γ-Cu 2 (OH) 3 Cl and CuNiAl layered double hydroxide (LDH) and used as Fenton catalysts to mineralize aniline. They exhibit higher activity and efficiency than the two pure phases. The optimal composite can mineralize 95.1% aniline under circumneutral pH and exhibits good stability. HO˙ dominates the mineralization over γ-Cu 2 (OH) 3 Cl, whereas both HO˙ and O 2 ˙ − are responsible for mineralization over the composite and LDH. Cu + and oxygen vacancies (OVs) are related to HO˙ and O 2 ˙ − generation, respectively. The in situ fabrication of two phases with similar layered structures and Cu-oxo octahedra may provoke structural disorder, leading to more OVs and thereby O 2 ˙ − . HO˙ and O 2 ˙ − play different roles in aniline mineralization. HO˙ prefers to initially degrade aniline into carboxylic acids but is less reactive in further mineralizing carboxylic acids owing to the electrophilicity of HO˙, whereas O 2 ˙ − prefers to further mineralize carboxylic acids considering its strong nucleophilicity. Aniline mineralization occurs via denitrification and deamination routes. The γ-Cu 2 (OH) 3 Cl/LDH composite could combine favorable characteristics of both phases, offering more HO˙ and O 2 ˙ − to allow for the successive mineralization of refractory organic pollutants.