Mercury and Organic Pollutants Removal from Aqueous Solutions by Heterogeneous Photocatalysis with ZnO-Based Materials.

The removal of four Contaminants of Emerging Concern, namely bisphenol A, sulfamethoxazole, diclofenac and benzotriazole; two odorous compounds, geosmin and 2-methylisoborneol, frequently detected in recirculating aquaculture systems; and Hg(II) was investigated using ZnO-based materials doped or co-doped with Ce and Cu under simulated solar radiation. Photocatalysts were synthetized via a hydrothermal route and their efficiency was assessed by changing some operational parameters in different water matrices of increasing complexity. The mixture of contaminants was successfully degraded in just 1 h, while the complete mineralization was achieved in a few hours; experiments performed in an actual aquaculture water confirmed the efficiency and broad versatility of the synthesized materials.

Photocatalytic abatement of emerging pollutants in pure water and wastewater effluent by TiO2 and Ce-ZnO: degradation kinetics and assessment of transformation products.

Here, the performances of two different catalysts, Ce-ZnO and TiO2 synthetized in our laboratories, were compared with the commercial TiO2-P25 for degradation of a mixture of seven emerging pollutants under UV irradiation. The investigation included monitoring pollutants abatement in Milli-Q water and in wastewater effluent and identifying their transformation products by HPLC-HRMS. Structural characterization of intermediates supported by data available from literature allowed elucidation of the transformation pathways occurring in the presence of all investigated catalysts in the wastewater effluent. Preliminary results showed a good removal efficacy for almost all examined contaminants, even in real water matrix (i.e. wastewater effluent). The type of matrix and catalyst affects the number and/or the abundance of transformation products, which suggests differences in their transformation routes.

UV-Cured Chitosan and Gelatin Hydrogels for the Removal of As(V) and Pb(II) from Water.

In this study, new photocurable biobased hydrogels deriving from chitosan and gelatin are designed and tested as sorbents for As(V) and Pb(II) removal from water. Those renewable materials were modified by a simple methacrylation reaction in order to make them light processable. The success of the reaction was evaluated by both 1H-NMR and FTIR spectroscopy. The reactivity of those formulations was subsequently investigated by a real-time photorheology test. The obtained hydrogels showed high swelling capability reaching up to 1200% in the case of methacrylated gelatin (GelMA). Subsequently, the Z-potential of the methacrylated chitosan (MCH) and GelMA was measured to correlate their electrostatic surface characteristics with their adsorption properties for As(V) and Pb(II). The pH of the solutions proved to have a huge influence on the As(V) and Pb(II) adsorption capacity of the obtained hydrogels. Furthermore, the effect of As(V) and Pb(II) initial concentration and contact time on the adsorption capability of MCH and GelMA were investigated and discussed. The MCH and GelMA hydrogels demonstrated to be promising sorbents for the removal of heavy metals from polluted waters.

Production of High Galacto-oligosaccharides by Pectinex Ultra SP-L: Optimization of Reaction Conditions and Immobilization on Glyoxyl-Functionalized Silica.

A rational optimization for the synthesis of galacto-oligosaccharides (GOS) from lactose catalyzed by ß-galactosidase from Aspergillus aculeatus, included in the commercial product Pectinex Ultra SP-L, has been performed by using experimental design and surface response methodology. This accurate tool optimized empirical production of the most desired high-GOS (tri-GOS and tetra-GOS) up to 16.4% under the following reaction conditions: 59 °C, 4 U/mL free enzyme concentration, pH 6.5, 250 g/L initial lactose concentration, and 20 h of reaction. The statistical analysis revealed temperature and initial lactose concentration as critical parameters. The successful immobilization of the enzyme on a glyoxyl-functionalized porous silica support slightly increased the yield toward high-GOS (17.6%), especially tri-GOS yield (15.3%), under the optimized reaction conditions as compared to the free enzyme. Furthermore, the promotion of the transgalactosylation reaction toward tri-GOS production increased 1.5-fold the productivity of high-GOS as compared to the free enzyme.

Superoxide limits cyclosporine-A-induced formation of peroxynitrite in endothelial cells(2).

Peroxynitrite (ONOO(-)) is a potent oxidant formed by the nonenzymatic reaction between superoxide anion (O(2)(*-)) and nitric oxide (NO*) in a one-to-one stoichiometry. Accumulated evidence suggests that endothelial dysfunction coincides with an enhanced NO* synthase expression and O(2)(*-) production, facilitating ONOO(-) formation. In vivo, formation of ONOO(-) has been associated with atherosclerosis and vascular aging. The immunosuppressor Cyclosporine A (CsA) has been associated to human endothelial dysfunction and accelerated atherosclerosis. We have previously shown that CsA induced a transcriptionally mediated increase of the eNOS gene expression and that CsA induced the formation of nitric oxide, O(2)(*-), and ONOO(-) in vascular endothelial cells. In this work, we evaluate the CsA-induced relative amounts of formation of O(2)(*-) and NO*, providing data consistent with a role of O(2)(*-), and not NO*, as the limiting factor in the CsA-dependent intracellular formation of ONOO(-) in vascular endothelial cells. Furthermore, when endothelial cells were treated with CsA in a situation of increased generation of superoxide such as that provided by high glucose levels, a further increase in the formation of peroxynitrite was detected. The temporal availability of O(2)(*-) for peroxynitrite formation may thus become critical in the pathophysiological scenarios where reactive nitrogen intermediates are operative.

Home-prepared anatase, rutile, and brookite TiO(2) for selective photocatalytic oxidation of 4-methoxybenzyl alcohol in water: reactivity and ATR-FTIR study.

TiO(2) catalysts of anatase, rutile and brookite phase were prepared at low temperature and tested for carrying out the photocatalytic partial oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde (p-anisaldehyde) in organic-free water suspensions. Traces of 4-methoxybenzoic acid and open-ring products were the only by-products present, CO(2) being the other main oxidation product. Rutile exhibited the highest yield to p-anisaldehyde (62% mol) at a rate of the same order of magnitude of that showed by the other samples. Commercial rutile and anatase photocatalysts were also used for the sake of comparison. The samples have been characterised by an in situ ATR-FTIR investigation carried out in conditions simulating the photoreaction ones.