Fabrication and characterization of TiO2-loaded Moringa oleifera gum-activated carbon and the photo-catalytic degradation of phosphate in aqueous solutions

Abstract

Titanium dioxide nanoparticles (TiO2NPs) were synthesized and loaded onto Moringa oleifera gum-activated carbon (MOGAC) by sol–gel method to form nanocomposites. The phosphate removal efficiency of the nanocomposites was studied under green, red, blue, and white LED irradiation and sunlight. The surface morphology, phase, and crystal structure of the obtained MOGAC, TiO2NPs, TiO2/MOGACNPs, and phosphate-loaded TiO2/MOGACNPs were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. Fourier transform infrared spectroscopy confirmed the presence of various functional groups. The absorption range and band gap energy were investigated via UV–Vis diffuse reflectance spectroscopy, Raman spectra and Brunauer–Emmett–Teller analysis. The UV–Vis spectrophotometry results of the NPs irradiated by a red LED, after being treated with an aqueous (PO4 3−) solution, showed 96% phosphate removal within 50 min. A significant increase in the reaction rate of phosphate degradation was observed with TiO2/MOGACNPs under various light sources. This increase is due to the high migration efficiency of photoinduced electrons and the inhibition of charge carrier recombination due to the electronic interaction between TiO2NPs and MOGAC. The kinetic data were also described by pseudo-first-order kinetic models. With the use of MOGAC, the study has opened an entirely various avenues of research in chemical removal as a new, modern, and safe technique.