Investigation of the photocatalytic activity of a novel-driven photocatalyst L-cysteine-TiO2/Bi2O3 under visible light irradiation: process optimization and modeling

In this study, L-cysteine (C-N-S triple doped)-TiO2/Bi2O3 visible driven photocatalyst was successfully synthesized and its properties were identified by diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), Fourier transform infrared (FT-IR), field emission scanning electron microscopy/energy-dispersive analysis of X-ray (FESEM-EDX), and X-ray diffraction (XRD). The photocatalytic performance of the prepared nanocomposite was evaluated for the photodegradation reaction of direct red 16 dye (DR16) under visible light. Our findings show that L-cysteine (C-N-S triple doped)-TiO2/Bi2O3 photocatalyst has an excellent photocatalytic activity compared to that of L-cysteine (C-N-S triple doped)-TiO2 and pure TiO2. Accordingly, DRS analysis, the absorption spectrum edge of the modified samples indicated a shift into longer wavelengths. The photocatalyst is found to be reusable. The design of experiments was performed based on the response surface method (RSM) to appraise the effects of variables inclusive of initial pH, contact time, direct red 16 (DR16) concentration, and catalyst concentration. The optimum condition was obtained at initial pH 4, contact time 120 min, DR16 concentration 20 mg/L, and catalyst dosage 1 g/L. The TiO2/L-cysteine/Bi2O3 photocatalyst showed highly efficient photocatalytic performance, which was suitable for water treatment.

Automated summary

The study synthesized a visible-driven photocatalyst and evaluated its photocatalytic performance for water treatment. The nanocomposite showed excellent photocatalytic activity compared to pure TiO2, and the optimal conditions were determined for the photocatalytic reaction.