Visible-solar-light-driven photo-reduction and removal of cadmium ion with Eosin Y-sensitized TiO2 in aqueous solution of triethanolamine

Abstract

Abstract Cadmium is toxic to humans, animals, and plants, and show persistence because of its non-degradability. Photo-reduction of cadmium ion (Cd (II)) was studied with Eosin Y-sensitized TiO2 photocatalyst for the reduction/removal of Cd (II) in an aqueous medium under visible-solar light. Triethanolamine (TEOA) was used as a sacrificial electron donor. The band-gap of Eosin Y-sensitized TiO2 photocatalyst was reduced by ∼1 eV, and visible light activity was observed for Cd (II) photo-reduction. Parametric studies were performed for visible-solar light intensity, solution pH, and initial concentrations of metal ion, dye, photocatalyst, and an electron donor. Complete photo-reduction of Cd (II) was achieved in 3 h at a pH of 7.0 and a light intensity of 100 mW cm−2. The photo-reduction rate of Cd (II) in TEOA solution followed Langmuir-Hinshelwood rate equation. The highest apparent quantum yield (∼0.3%) for Cd (II) photo-reduction was observed at the lower visible light intensity with illuminated Eosin Y-sensitized TiO2.