Nalenthiran Pugazhenthiran

ZnO supported CoFe2O4 nanophotocatalysts for the mineralization of Direct Blue 71 in aqueous environments.

In this study, an attempt was made to render both the magnetic and photocatalytic properties in a semiconductor material to enhance the efficiency of degradation and recycling possibility of magnetic nanophotocatalysts. CoFe2O4 and CoFe2O4 loaded ZnO nanoparticles were prepared by a simple co-precipitation method and characterized using various analytical tools and in addition to check its visible light assisted photocatalytic activity. CoFe2O4/ZnO nanocatalyst coupled with acceptor, peroxomonosulphate (PMS) showed 1.69-fold enhancement in Direct Blue 71 (triazo dye; DB71) mineralization within 5h. The accomplished enrichment in decolorization was due to the production of more number of non-selective and active free radicals at the catalyst surface.

Investigation on photocatalytic potential of Au–Ta2O5 semiconductor nanoparticle by degrading Methyl Orange in aqueous solution by illuminating with visible light

A semiconductor photocatalytic process has shown great potential as a low cost, environmentally friendly and sustainable treatment technology for the treatment of wastewater. Hence, a wide band gap Ta2O5 semiconductor nanoparticle was prepared by the hydrothermal method and considerable efforts have been taken to narrow the band gap, i.e., the surface modification has been done with a noble metal (Au0) by a deposition precipitation method. As synthesized, Au–Ta2O5 semiconductor was well characterized by X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), transmission electron microscopy (TEM) and diffused reflectance UV-vis spectroscopy (DRS). The photocatalytic potential of Au–Ta2O5 semiconductor was investigated by degrading Methyl Orange in the presence and absence of electron acceptors by illuminating with visible light of intensity 80 600 ± 10 Lux.

HPA immobilized on the functionalized Ti-MCM-41 nanochannels for photocatalytic degradation of ternary azo dye effluents

Solid-state heteropolytungstic acid (HPA) clusters were covalently linked into amino and mercapto functionalized Ti-MCM-41 nanoporous channel by in situ synthesis processes to effectively use as a recyclable photocatalyst for degradation of ternary azo dyes consisting of methyl orange (MeOr), acid orange 10 (AO-10) and acid red 88 (AR88) before and after dying processes. The structure and morphology of as synthesized nanoporous hybrid catalyst (HPA immobilized mercapto and amino functionalized Ti-MCM41) was characterized by means of Fourier transform infrared analysis (FT-IR), Phosphorus-31 Nuclear Magnetic Resonance (31P-NMR) analysis, X-ray diffraction (XRD) analysis, N2 adsorption studies, diffused reflectance studies (DRS) and transmission electron microscope (TEM) measurements. The immobilization of HPA on functionalized Ti-MCM-41 acts as coupled semiconductor with higher specific area and superior active sites for photocatalytic degradation of ternary azo dyes. The hybrid catalyst was found to be very stable and did not lose it activity even after performing three consecutive irradiation experiments with azo dye mixtures; hence it may be reusable for further degradation of dye mixtures.

Green synthesis of porous Au-Nx-TiO2 nanospheres for solar light induced photocatalytic degradation of diazo, triazo dyes and their eco-toxic effects

Porous TiO2 nanospheres and nitrogen doped TiO2 nanospheres (Nx-TiO2 NSPs) in the range of 150 to 200 nm were synthesized through a facile one pot green synthesis route and their surface was modified using plasmonic gold nanoparticles (Au NPs) without altering their anatase phase. These nanospheres were characterized using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Brunauer–Emmett–Teller (BET) surface area measurements, and scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. The gold deposited photocatalysts (porous Au–Nx-TiO2 and Au–TiO2 NSPs), by virtue of their visible-light absorption properties and the rapid charge separation at the Au/TiO2 and Au/Nx-TiO2 interfaces, demonstrated an excellent photocatalytic activity under direct solar light irradiation towards the degradation of diazo and triazo dyes such as reactive red 120 (RR120) and direct blue 71 (DB71), respectively. The correlation between the amount of HO˙ formation and the amount of photocatalytic degradation indicated that the photocatalytic degradation of the azo dyes increased with the respective HO˙ formation. In addition, the real time applications of the photocatalytic degradation of both diazo and triazo dyes were studied in tap water. The eco-toxicity study disclosed that the toxicity of the degradation intermediates was effectively removed with respect to the irradiation time owing to the mineralization of both azo dyes and their intermediates. The stability study revealed the photocatalytic activity of Au–Nx-TiO2 NSPs in upto eight consecutive cycles without any reduction of their initial photocatalytic activity. The results indicated that industrial wastewater in large volumes can be processed rapidly using the porous Au–Nx-TiO2 NSPs just by exploiting sunlight.