Synthesis of TiO₂ Using <i>Calotropis gigantea</i> for Visible Light Excitation and Degradation of Congo Red Dye

Abstract

Green synthesized TiO2 (CG-TiO2) was prepared from Titanium isopropoxide (TTIP) precursor using aqueous leaf extract of Calotropis gigantea (CG). The CG-TiO2 was prepared with different mixing ratios of CG and TTIP varying from 1:3 to 1:5 and at different synthesis conditions, that is, mixing time, temperature, and calcination temperature. Morphological analysis indicated spherical nanoparticle clusters of CG-TiO2 with particles of an average size of 42 nm. The study indicated visible light excitation of CG-TiO2 and effective removal of Congo red from aqueous solution under visible light irradiation. A maximum Congo red removal efficiency of 97% was obtained within 2 h under the following conditions: Sample B (30 g leaves in 100 mL distilled water boiled for 2 h at 90°C); TTIP:CG – 1:3; mixing time and temperature – 2 h and 27°C, respectively; calcination temperature – 300°C.