Photocatalysis Applications: Photoreforming of Biomass Derivatives and Organic Drugs Removal. Preparation and Characterization of Nanocomposites Materials

To meet the energy needs of the world, most of the energy is still being obtained from fossil fuels including coal, oil and natural gas. Fossil fuels are not considered environmentally friendly because their combustion releases greenhouse gas emissions that cause global warming. There are several potential advantages to using more renewable energy, such as lowering emissions that contribute to global warming, diversifying energy sources, and reducing reliance on the fossil fuel energy market. Biomass includes all organic material that is derived from plants. The total carbon footprint associated with energy generation can be decreased by combining the use of solar light and fuels obtained from biomass. Hydrogen gas (H2) is considered as a very efficient, clean and promising energy source. It can be generated from water and renewable energy resources. The importance of using H2 as a fuel derives from the fact that it has an energy efficiency of 122 kJ·mol-1, which is higher than that of gasoline or of any other fossil fuel. It is a big challenge to develop sustainable options for green H2 production. In this context, photocatalysis is considered an environmentally friendly process used in photoreforming of organic compounds and pollutant removal to produce contemporary H2 and high added value compounds. The use of photocatalysis has several advantages for the environment, including mild operating conditions (i.e. room temperature and ambient pressure), the absence of harmful chemical solvents, utilization of solar light as irradiation source, the easy integration with other physical and chemical technologies, e.g. membrane separation. The main focus of this Ph.D. thesis is to synthesize different TiO2 based and alternative photocatalysts and investigate their applications towards production of high value chemicals, H2 production and organic drugs removal. The prepared photocatalysts were characterized by XRD, SEM, TEM, Raman, BET, EPR, PL, DRS, DRIFTS, TPD, FTIR, XPS and EDS. Biomass derivatives including glucose, fructose, glycerol, furfuryl alcohol, ethanol, methanol, formic acid and triethanolamine have been used to produce H2 and high valuable chemicals, for instance, arabinose, erythrose, gluconic acid, formic acid, furfural, glyceraldehyde, dihydroxyacetone and glycolic acid, are of particular interest for further applications. The results obtained in laboratory scale were extended to pilot plant scale in the Plataforma Solar de Almería (Spain). Notably, the prepared photocatalysts were used for H2 production in a 25L photoreactor through photoreforming of glycerol (waste generated in biodiesel industries) and other organic compounds under direct sunlight in environmentally green conditions.ZnIn2S4, synthesized by a simple hydrothermal method in which the carcinogen thioacetamide, universally used as a precursor, for the first time, replaced successfully the harmless thiourea, was synthetized as alternative TiO2 photocatalyst and was activated by solar light irradiation. Its photocatalytic efficiency was investigated for the selective oxidation of aromatic alcohols to their corresponding aldehyde, of the lignocellulose derivative 5-hydroxymethyl-2-furfural (HMF) in water solution, and photoreforming of furfuryl alcohol under green conditions. The high value HMF derivatives were 2,5-diformylfuran (FDC), 5-formyl-2-furancarboxylic acid (FCA) and 5-hydroxymethyl-2-furan carboxylic acid (HMFCA), that are of particular interest for the polymer industry; H2 was produced from triethanolamine, methanol and furfuryl alcohol.With the growth of population and industrialization, almost all water sources are contaminated mainly by agricultural and industrial waste. Molecules of pharmacological importance present in drugs are widespread in the environment. Their concentrations have been found to range between ng and µg per liter in seawater, lakes, rivers, surface waters, urban wastewater and drinking water. A part of this thesis has been also focused on the photocatalytic degradation of most used organic drugs such as tetracycline, oxytetracycline and lincomycin in the presence of different photocatalysts.