Synthesis, Characterization and Performance Evaluation of TiO2-SnO2 photocatalyst for Removal of Toxic Hexavalent Chromium

Abstract

Heavy metal pollution bears a substantial threat to flora, fauna, humans, and milieu. The elimination of hexavalent chromium [Cr(VI)] from polluted water is of considerable research interest from a health and environmental viewpoint. This work aims for photocatalytic reduction of Cr(VI) to Cr(III) using TiO<inf>2</inf> and SnO<inf>2</inf> as catalysts. The process parameters varied are catalyst dosage, pH, initial concentration of model pollutant with citric acid (CA) as a scavenger. TiO<inf>2</inf>-SnO<inf>2</inf> (in the molar ratios 10:1, 20:1, 30:1, and 40:1)-based catalysts were synthesized using the hydrothermal method. The 40:1 catalyst showed higher photoactivity than other catalysts and could extend the optical activity in the visible light region. The complete reduction of Cr(VI) with a concentration of 15 mg/L and pH 3.0 was achieved when catalyst concentration was 0.6 g/L over a period of 30 min. The XRD (X-Ray Diffraction Spectroscopy) and ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy) results confirm the Ti-Sn heterojunction formation, and XPS (X-ray Photoelectron Spectroscopy) analysis corroborate the presence of trivalent chromium [Cr(III)] on TiO<inf>2</inf>-SnO<inf>2</inf> catalyst after reduction. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.