Remarkable recycling processes of conjugated polymers with titanium dioxide quantum dots as photocatalysts for photodegradation of hazardous industrial wastewater

This study presents the synthesis and characterization of a novel polyaniline-titanium dioxide quantum dot (PA-TQD) composite for enhanced photocatalytic degradation of hazardous industrial wastewater. The composite was synthesized via in-situ polymerization and characterized using FTIR, XRD, TEM, BET, and TGA, confirming the integration of TiO2 quantum dots (2.8-5.3 nm) into the polyaniline matrix (particle size 35-40 nm). BET analysis revealed a surface area of 50.30 m(2)/g for PA-TQD, significantly higher than 28.18 m(2)/g for pure polyaniline, contributing to its improved photocatalytic activity. Photocatalytic degradation experiments on methyl orange dye demonstrated a 60.1% degradation efficiency under xenon irradiation, compared to 35% for polyaniline alone. The photocatalytic rate constant of PA-TQD was 0.032 min(-)(1), indicating enhanced performance. In recycling tests, PA-TQD retained 73.8% of its photocatalytic efficiency after four cycles, showcasing strong reusability. TGA analysis confirmed the composite's enhanced thermal stability, with minimal weight loss up to 250 degrees C. COD analysis of real industrial wastewater samples showed effective pollutant reduction, with COD values for PA-TQD ranging from 756 to 1212 ppm. However, further optimization is needed to meet regulatory limits set by Saudi environmental laws (<1000 ppm COD). The synergy between polyaniline and TiO2 quantum dots enhances charge separation, increases active sites, and makes PA-TQD a promising recyclable photocatalyst for sustainable wastewater treatment applications.