Nickel-titanium dioxide-Fuller?s earth nanocomposites: Synthesis, characterization and application as a photocatalyst in aqueous methylene blue degradation under visible light irradiation

Nickel doped Titanium dioxide was immobilised on Fuller's earth (NiTF) through a sol-gel process and the resultant nanocomposite was characterized with X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, Thermogravimetric Analysis, X-ray photoelectron spectroscopy and Differential Reflectance Spectroscopy. The material calcined at 500 degrees C was tested as a photocatalyst for decolourisation of aqueous Methylene Blue. Catalyst loading, dye concentration, and pH were used as the process variables during the reactions. A catalyst loading of 0.1 gL-1 could decolorise a 5 x 10-5 M dye solution to the extent of 96.15 % at pH 9.0 under visible light irradiation for 90 min. The degradation of the dye was seen to follow pseudo first order kinetics. Trapping experiments performed to study the effects of the presence of reactive species in the reaction mixture indicated center dot O2- and h+ to be the main reactive species degrading the dye photocatalytically. Use of Fuller's earth as a support for TiO2 was shown to improve its adsorption ability under dark conditions. The use of Fuller's earth as a support for Ni-TiO2 indicated that metal-semiconductor-clay nanocomposite could be developed as cost-effective, potent and efficient photocatalysts for environmental applications.

Automated summary

Nickel doped Titanium dioxide immobilised on Fuller's earth (NiTF) was characterized and tested as a photocatalyst for decolourisation of aqueous Methylene Blue. Results showed that a catalyst loading of 0.1 gL-1 could decolourise a 5 x 10-5 M dye solution by 96.15% under visible light irradiation for 90 min at pH 9.0. Trapping experiments indicated that reactive species·O2- and h+ were the main species degrading the dye photocatalytically. The use of Fuller's earth as a support for Ni-TiO2 demonstrated the potential of metal-semiconductor-clay nanocomposites as cost-effective and efficient photocatalysts.