Immobilization of TiO2 Nanoparticles Over Treated Natural Aluminasilicate for Hydrogen Production: Effect of Support Treatment and Operational Conditions of Process

In the present research, the photocatalytic water splitting process has been carried out over titania nanoparticles immobilized on parent clinoptilolite and ion exchange-treated clinoptilolite with the aim of understanding the effects of chemical treatment method on the physicochemical properties and performance of catalyst, and assessing the effects of operational parameters including irradiation time, photocatalyst dosage and solution pH. To this aim, 10 wt.% of TiO2 nanoparticles were loaded over zeolitic supports using facile and cost effective solid state dispersion (SSD) method. Moreover, the synthesized photocatalysts were characterized by XRD, FESEM, EDX, BET, PL and UV-vis techniques. The characterization results indicate that less population of surface particle aggregates, a better dispersion of titania particles and stronger metal-support interaction as a result of higher surface area and more accessibility of the zeolite micro-channels were achieved using modified clinoptilolite support. The fine dispersion of TiO2 particles reflects higher surface density of active sites and separation efficiency of electron-hole pairs, which accounts for their better photocatalytic performance. Employing the ion exchange- treated clinoptilolite as support led to 30% increase in the photocatalytic activity of TiO2-treated clinoptilolite for hydrogen evolution compared to that of TiO2-based composite containing the bare clinoptilolite. By assessing the influence of the operational conditions on the efficiency of water splitting, a maximum hydrogen evolution (859.74 µmol g-1 h-1) was obtained with optimum condition set at irradiation time of 4 h, solution pH of 10 and photocatalyst dosage of 1 g L-1, which is about 12 times greater than that of pure TiO2 as the reference sample.