Titania nano-photocatalysts synthesized by ultrasound and microwave methodologies: Application in depuration of water from 3-chloropyridine

Abstract

The effect of aging the gel under ultrasonic (us) and microwave (mw) irradiation on the characteristics of the synthesized solids was studied. Sonication ensured the obtention of pure anatase nanoparticles in high crystalline state and generally led to obtain a high surface area and more active photocatalyst. Catalysts were characterized by a wide range of physical techniques (ICP-MS, N 2 isotherms, XRD, UV–vis and TEM). The total degradation of 3-chloropyridine was studied under titania-based photocatalysts, this degradation followed a zero-order kinetics respect to 3-chloropyridine. In our conditions, 100 ppm of 3-chloropyridine was degraded completely within ca. 8 h of UV-radiation (365 nm wavelength) on bare-titania systems. Some reactions intermediates were identified by SPME-GC–MS and a plausible mineralization route was suggested implying two parallel routes with hydroxylation and ring opening prior to or after the release of chloride ions. The modification of titania surface with metals (Fe, Pt, Pd) was detrimental for photocatalysis.