Efficient Removal of Crystal Violet Dye Using Visible-Light-Active Mixed Phase Titanium Dioxide Nanoparticles: Synthesis, Degradation Kinetics, and Reusability Assessment

Abstract

This study reports the synthesis of mixed-phase TiO₂ nanoparticles via a simple co-precipitation method, followed by calcination at 400–650 °C. The photocatalytic degradation of crystal violet (CV) dye under visible light was systematically investigated by optimizing key parameters including calcination temperature, H₂O₂ concentration, dye concentration, catalyst dose, and pH. TiO₂ calcined at 550 °C showed the highest degradation efficiency of 76.36% (k = 0.0062 min⁻¹, r² = 0.98436) over 240 min. The addition of 6 mL H₂O₂ enhanced the removal efficiency to 88.7% within 75 min (k = 0.05472 min⁻¹, r² = 0.96233), following pseudo-first-order kinetics. The results demonstrate the potential of the synthesized TiO₂ for effective dye degradation under visible light, highlighting its applicability in wastewater treatment.