TiO2 Quantum Dots Supported on Poly(Chloroaniline): Enhanced Photocatalytic Degradation and Recyclability for Wastewater Treatment

Vollständiger Abstract

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A poly(chloroaniline)/TiO2 quantum-dot (ClAn/TiQD) hybrid photocatalyst was prepared by in situ oxidative polymerization to address the limited visible-light utilization and charge recombination commonly associated with TiO2-based systems in dye-bearing wastewater treatment. Structural and spectroscopic analyses confirmed retention of anatase TiO2 after hybrid formation, preservation of the conjugated polymer backbone, and interfacial coupling between TiQD and ClAn. TEM showed ClAn particles of 33–42 nm, TiQD domains of 3.9–6.9 nm, and hybrid particles of 22–25 nm. The composite also exhibited improved thermal resistance relative to ClAn, with the principal degradation stage shifted to higher temperature and the total mass loss reduced from about 54% to 49%. Optical and textural measurements showed that hybridization lowered the apparent band gap from 3.48 eV for ClAn to 2.33 eV for ClAn/TiQD, while TiQD showed 2.25 eV; the corresponding BET surface areas were 29.6, 54.4, and 188.8 m2 g-1, respectively. Under xenon irradiation, methyl orange degradation followed pseudo-first-order kinetics with rate constants of 4.88 × 10-3, 18.02 × 10-3, and 15.77 × 10-3 min-1 for ClAn, ClAn/TiQD, and TiQD, giving decolorization efficiencies of 49.5%, 79.5%, and 93% after 130 min. In real dye-house wastewater under sunlight, the composite reduced COD more effectively than ClAn, although TiQD remained the most active phase. After six reuse cycles, the hybrid retained markedly better activity than the neat polymer. These results show that ClAn/TiQD functions as effective interfacial hybrid that substantially improves polymer performance and offers a practical route for solar-assisted treatment of recalcitrant dye effluents.