Enhanced degradation of crystal violet using PANI-ZnO nanocomposites: Electro-oxidation and photocatalysis studies

Abstract

This work compares the transformation capabilities of crystal violet (CV), a toxic cationic dye of the triphenylmethane family, by advanced oxidation processes, especially heterogeneous photocatalysis and electrochemical oxidation, on new nanocomposite materials with a composition of zinc oxide (ZnO) and polyaniline (PANI) by chemical polymerization in solution. Concerning the synthesis of PANI, we have exploited the radical oxidative polymerization method; this latter is functional and uncomplex, as it does not require expensive equipment, using ammonium persulfate as an oxidant with a part of monomer (Aniline) to remove pollutants present in the environment. After physicochemical analyses including FTIR, SEM, and electrochemical characterizations by cyclic voltammetry and conductimetry, the results show that the photocatalytic activity of PANI-ZnO5 % resulted in a better yield (85 %) compared to PANI alone and other composites (PANI-ZnO10 % and PANI-ZnO20 %). However, the electro-oxidation discoloration rates on all PANI alone and PANI-ZnO composite electrodes (5 %, 10 %, and 20 %) reached almost 99 %. To deepen our understanding, computational DFT calculations were employed, complementing experimental findings, and together, they contribute to elucidating the intricate mechanisms underlying the enhanced performance of these nanocomposite materials in both photocatalysis and electrochemical oxidation processes.