Green synthesis of BiVO4/Eco-graphene nanostructures for the elimination of sulfamethoxazole by adsorption and photo-degradation using blue LED light.

Photo-catalysts based on BiVO4 (BV) and Eco-graphene (EG) were synthesized and obtained in a single step with high-quality properties. These nanostructures (NEs) were obtained through a green chemistry route and by adding 2, 3, and 5 wt% of a homemade EG. The BV/X EG NEs (where X = corresponds to the weight % of EG) demonstrated high photocatalytic activity, obtaining Sulfamethoxazole degradation percentages of 40, 45, 52, and 57 for BV, BV/2 EG, BV/3 EG, and BV/5 EG respectively, using a blue LED light. In addition, it was observed that the presence of EG slightly affected the surface area and porosity of BV. Moreover, it was observed that the presence of EG stabilized the scheelite monoclinic phase (m-s), and decreased the crystal size and band-gap values of BV-based samples. It was detected that EG contents increased the BV reduction, creating oxygen vacancies and V4+ states, which favored electron transfer, enhanced the photo-catalytic activity, and decreased the recombination rate. The adsorption influence of the BV/EG system was also studied. Finally, the stability tests of these materials after four cycles of reuse allowed keeping practically the full degradation capacity, demonstrating that these NEs represent a promising material driven by visible light that can be used for wastewater decontamination in the presence of drugs.

Influence of the physicochemical properties of inorganic supports on the activity of immobilized bacteria for water denitrification.

The denitrification of polluted water was studied by using supported E-coli bacteria. The physicochemical characteristics of supports and the influence of these properties on the bacteria performance were analyzed. Inorganic supports oxides and zeolites were selected in order to cover a wide range of porosity and surface chemical properties and the denitrification process systematically studied. Consecutive denitrification cycles in batch experiments and the toxicity of supports were also analyzed. The acidity of supports provokes a slower reduction processes, favoring also a high concentration of intermediate nitrites in solution for longer periods. The NO3(-) reduction is faster than the NO2(-) one, being also less influenced by the support characteristics. Anyway, the total denitrification is reached in all cases. The best performance was obtained with bacteria supported on mesoporous and non-acid silica support.

Tailoring activated carbons for the development of specific adsorbents of gasoline vapors.

The specific adsorption of oxygenated and aliphatic gasoline components onto activated carbons (ACs) was studied under static and dynamic conditions. Ethanol and n-octane were selected as target molecules. A highly porous activated carbon (CA) was prepared by means of two processes: carbonization and chemical activation of olive stone residues. Different types of oxygenated groups, identified and quantified by TPD and XPS, were generated on the CA surface using an oxidation treatment with ammonium peroxydisulfate and then selectively removed by thermal treatments, as confirmed by TPD results. Chemical and porous transformations were carefully analyzed throughout these processes and related to their VOC removal performance. The analysis of the adsorption process under static conditions and the thermal desorption of VOCs enabled us to determine the total adsorption capacity and regeneration possibilities. Breakthrough curves obtained for the adsorption process carried out under dynamic conditions provided information about the mass transfer zone in each adsorption bed. While n-octane adsorption is mainly determined by the porosity of activated carbons, ethanol adsorption is related to their surface chemistry, and in particular is enhanced by the presence of carboxylic acid groups.

Design of low-temperature Pt-carbon combustion catalysts for VOC's treatments.

Two series of Pt/C-catalysts were prepared using pure carbon aerogels as supports. The influence of porosity, surface chemistry and Pt dispersion on the activity of Pt/C combustion catalysts was analyzed. The synthesis of the supports was fitted to have a monomodal pore size distribution in the meso and macropore range respectively. Both supports were functionalized by oxidation treatment with H(2)O(2) or (NH(4))(2)S(2)O(8). These treatments did not modify the porosity significantly, but the surface chemistry changed from basic to acid as oxygen content increased. In this way, Pt-dispersion decreased as a result of the low thermal stability of surface carboxylic acid groups. Benzene was selected as target VOCs and the catalytic combustion performance depended mainly on the porous texture and Pt-dispersion, while the variations in the surface chemistry of carbon supports due to oxidation treatments seemed to have a weak influence on this kind of reaction.

Molybdenum carbide formation in molybdenum-doped organic and carbon aerogels.

A Mo-doped organic aerogel and its corresponding carbonized derivative at 1000 degrees C were obtained. Both samples were treated in a H(2)/Ar flow. After this treatment, a mixture of Mo(VI) and Mo(2)C was detected in both samples. The results obtained indicate that the presence of H(2) in the gas flow is necessary to obtain the carbide phase, due to the formation of CH(4) or even CH(x)() species that reduce and carburize the molybdenum oxide phase. Carburization of the Mo-doped organic aerogel yielded better results compared with carburization of the Mo-doped carbon aerogel.