Green technique of visible light active titanium dioxide nanoparticles using starch for the degradation of organic pollutant

The design of titanium dioxide nanoparticles (TiO2 NPs) is crucial. Therefore, the visible light-activated TiO2 NPs were proposed using a sol-gel green method with reduced optical bandgap energy from 3.20 eV of pure anatase TiO2 into 3.00 eV. The obtained electrochemical bandgap (2.81 eV) which was analyzed by cyclic voltammetry revealed an insignificant difference compared to the optical bandgap. X-ray diffraction analysis verified TiO2 NPs composed of an anatase-brookite phase with a crystallite size of 8 nm. The particle size of TiO2 NPs was confirmed by high-resolution transmission electron microscopy analysis (11.63 +/- 1.47 nm). Due to the high photocatalytic performance of the mixed-phase TiO2 NPs, the optimum concentration (6 ppm) of neutral red (NR) dye was completely degraded within 30 min under visible light. Photoluminescence analysis revealed the improved electron-hole separation of the synthesized TiO2 NPs. center dot O2- acted as the predominant role of reactive oxygen species in the removal of NR dye. The degradation kinetics of NR obeyed the first-order kinetic and the adsorption data were fitted with the Langmuir isotherm model. TiO2 NPs maintained over 90% of its initial photocatalytic efficiency after five cycles. Thus, this study suggests that the TiO2 NPs have good potential as an effective photocatalyst in wastewater treatment.