Synthesis, characterization, and photocatalytic performance of methyl orange in aqueous TiO2 suspension under UV and solar light irradiation

Abstract

Nano-crystalline titanium dioxide (TiO2) photocatalyst has been extensively utilized in the last few decades because of its strong oxidizing power, redox selectivity, and higher photocatalytic performance. In this work, TiO2 nanoparticle (NPs) was synthesized, characterized, and applied for the degradation of methyl orange (MO) dye in an aqueous solution under UV and solar light irradiations. The XRD results showed dominated anatase phase (82%) with a smaller crystalline size (18.23 nm). A rough surface with a uniform spherical shape was observed by SEM analysis. FTIR and UV–Vis/DRS spectroscopy confirmed the stretching vibration of the hydroxyl groups and higher absorption edge towards longer wavelength with smaller bandgap energy (3.12 eV) of TiO2 lattice structure. The activity of TiO2 NPs was carried out from the degradation of MO dye as a model contaminant for textile effluent in presence of UV/solar irradiation. The photodegradation efficiency of MO dye (15 mg L−1) was observed at 85.90% and 96.38% for 0.150 g and 0.030 g of TiO2 NPs at natural pH (7.0), after 5 h of UV and solar light irradiation. The respective rate constants were determined to be 0.0063 min−1 and 0.01 min−1 for UV and simulated solar light irradiation respectively, and exhibited the best-fitted kinetic model of pseudo-first-order. The photodegradation efficiency was increased with the decrease of pH, while efficiency decreased with an increase in initial dye concentration. The obtained result from TiO2 NPs was compared with commercially available Degussa P25 catalyst. The photocatalyst reusability test and reaction mechanism were also evaluated. The study suggests that TiO2 NPs are a promising photocatalyst that can be used for the degradation of organic dye compounds from textile wastewater towards the sustainable management of environment.