Photodegradation of methylene blue under direct sunbeams by synthesized anatase titania nanoparticles

Abstract

Surfactant-assisted titania nanoparticles have been successfully synthesized using an inorganic salt of titanium by controlled hydrolysis method. Anionic (Sodium dodecyl sulfate), nonionic (Brij C10) and cationic (Dodecyl amine) surfactants have been used to synthesize the titania nanoparticles. The XRD patterns of the 500 °C annealed nanoparticles exhibit technologically important anatase phase. Anatase to rutile transformation is observed for Ti-D-650 nanoparticles at lower temperature. It has been observed that the Ti-S-900 nanoparticles retained to the anatase phase at higher temperature up to 900 °C. The Brij C10 assisted nanoparticles (Ti-B-500) exhibited high surface area and lower crystallite size compared to other nanoparticles. In addition, Ti-B-500 samples exhibited wormlike mesopores structure. XPS study confirmed the presence of sulphur in Ti-B-500 nanoparticles, which creates an O–S mixed environment into the lattice. The nanoparticles also showed a red shift in the UV-DRS study with a lower band gap (indirect) energy about 3.02 eV. Impedance spectrum of the Ti-B-500 nanoparticles confirmed the enhanced electron–hole separation rate involved in the photodegradation process. Photodegradation rate of methylene blue [2 × 10 - 5(M)] with Ti-B-500 nanoparticles under direct sunbeams has been observed to be higher compared to other surfactant-assisted nanoparticles. The rate of photodegradation is found to be best at pH = 6.7 with a rate of 0.0864 min - 1 and the catalyst showed best reusability even after five cycles of experiment.