TiO2/CdS Heterojunction as an Efficient Photocatalyst for Degradation of Crystal Violet Dye and Antibacterial Activity

초록

In this study, TiO2 nanoparticles (NPs), CdS NPs and TiO2/CdS nanocomposite were synthesized via the sol-gel, hydrothermal and ex situ method, respectively. The synthesized materials were characterized using XRD, UV-vis DRS, FTIR, SEM, and EDX analysis. XRD analysis confirmed the crystalline structure of the as-prepared samples, while the bandgap energy of TiO2 NPs, CdS NPs, and TiO2/CdS nanocomposite were determined to be 2.98, 1.94, and 2.27 eV, respectively. Photocatalytic efficiency of TiO2 NPs, CdS NPs, and TiO2/CdS nanocomposite was systematically evaluated by photocatalytic degradation of crystal violet (CV) dye under visible-light irradiation. Under optimized reaction conditions of [CV concentration] = 20 mg/L, [catalyst dosage] = 0.25 g/L, and pH = 6, TiO2/CdS nanocomposite achieved 86.3% removal of CV within 180 min, outperforming pure TiO2 NPs (16.4%) and CdS NPs (66.9%). The enhanced performance of TiO2/CdS nanocomposite as compared to CdS NPs is attributed to improved charge separation via heterojunction formation, while significantly superior performance over TiO2 demonstrates successful visible-light activation. Further optimization study revealed that maximum removal efficiency of CV (97.1%) was achieved at lower dye concentration (10 mg/L). Photocatalytic degradation of CV followed pseudo-first-order kinetics. Moreover, scavenger experiments confirmed hydroxyl radicals ((OH)-O-center dot) as dominant reactive species. Furthermore, the TiO2/CdS nanocomposite demonstrated good reusability with minimal activity loss after five runs. Additionally, the as-prepared nanocomposites showed significant antibacterial activity against Pseudomonas aeruginosa (P. aeruginosa). The present study indicated that TiO2/CdS nanocomposite could be simultaneously used for degradation of organic pollutants as well as for removal of microorganisms while targeting environmental sustainability and water purification.

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