Enhanced photocatalytic degradation of diazo reactive blue 198 using ternary PANI-TiO2-CuO composites: Predicted degradation pathway, mechanism, and DFT calculations

This study investigated the preparation and detailed characterization of PANI (polyaniline)-TiO₂-CuO composites through in-situ chemical oxidation polymerization (PTCI) and mechano-chemical synthesis (PTCS) methods for comparison. The morphological characteristics of ternary composites depend on the ratios of PANI to binary TiO₂-CuO composite and the process of preparation. The photocatalytic degradation of diazo Reactive Blue 198 (RB-198) in the presence of the PTCS-81 composite (PANI: TiO₂-CuO composite with a mole ratio of 8:1, prepared using PTCS method) reached 90.4 % within 60 min. Recyclability tests revealed that the composites are stable, underscoring their potential as effective photocatalysts. The proposed degradation pathways of diazo RB-198 dye were discussed both experimentally and theoretically for the first time. The reactivity descriptors confirmed that the nitrogen atoms were favorably sensitive sites for radical attacks. Finally, the silico toxicity of potential photodegraded products of RB-198 was assessed via the computational toxicology method ProTox-3.0.