Bio-Inspired TiO_۲ Nanoparticles: Green Photocatalysts for Azo Dyes Driven by UV-A

This study reports the green synthesis of titanium dioxide nanoparticles (TiO₂ NPs) using Lansium domesticum Correa (LdC) peel extract as a natural stabilizing and reducing agent. The synthesized TiO₂ NPs exhibited a band gap of ۳.۲ eV and a zeta potential of –۴۷ mV, indicating strong colloidal stability. Their photocatalytic performance was evaluated in the degradation of Acid Yellow ۲۵ (AY۲۵) under various light sources, where UV-A irradiation showed the highest activity. The effects of dye concentration, pH, catalyst dosage, and exposure time were systematically investigated. Optimal conditions (۰.۱ g catalyst, ۲۰ mg L-۱ AY۲۵, pH ۳, ۲۴۰ min) resulted in ۹۵% degradation efficiency, following pseudo first order kinetics (R² = ۰.۹۹۳۲). Reusability studies demonstrated stable performance across three cycles with efficiencies of ۸۲%, ۷۸%, and ۷۳%. Scavenger tests identified e⁻, •O₂⁻, •OH, and h⁺ as the main reactive species involved in degradation. These findings highlight the potential of green synthesized TiO₂ NPs as efficient, reusable photocatalysts for sustainable wastewater treatment and environmental remediation.

Keywords:

TiO۲ nanomaterials , UV-A irradiation , Green synthesis , Sustainable wastewater treatment , Azo dye