Hydrothermal Sol-gel TiO2 Nanoparticles fixed to Clay and its Photocatalytic Application for the Degradation of Methyl Orange

In this paper, Clay-TiO2 nanomaterials were synthesized via hydrothermal sol-gel method using Ivorian clays and titanium tetra-isopropoxide as precursors. The synthesized composite was characterized through XRD, SEM/EDX, FTIR and BET surface measurements. The photocatalytic activity of composite towards the degradation of methyl orange (MO), a model pollutant, has been investigated under UV and simulated solar radiation. Comparative experiments done in a solution with and without H2O2 indicate an increase in efficiency for methyl orange removal from the polluted water in the presence of H2O2. The optimized parameters (contact time, amount of nanocomposite and amount of Fe2+/H2O2) allowed to reach removal efficiency up to 60 % of MO. Immobilization of TiO2 on clay facilitate repeated using of nanomaterials, two time.

Our Experience of Using Thermally Recycled Silica Gel in a Teaching and Small Research Laboratory Setting

Organic synthetic research laboratories generate a large amount of waste. Some of the waste is the silica gel used as the stationary phase in column chromatographic separations. Here, the authors discuss the possibility of recycling silica gel wastes thermally at 600 °C, at which temperature the remnant adsorbed organic material combusts. It could be shown that the recycled silica gel maintains its adsorption characteristics. The process could be repeated 10 times with any discernable deterioration of the separation properties of the silica gel for the product mixture of the reactions used in this research. In those cases where triphenyl oxide remained on the silica gel after the separation of the reaction mixture, such as after Wittig olefination and Appel-type reactions, an increase of phosphorus content was noted in the silica gel after thermal treatment. The original and recycled silica gel was partly analyzed by Brunauer-Emmett-Teller (BET) surface measurements, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and in inductively coupled plasma optical emission spectroscopy (ICP-OES). The process significantly reduced waste production in our laboratory and also led to a reduction in costs associated with acquiring new silica gel and with the management and the disposal of spent silica gel. A simple environmental impact assessment has been carried out.