Synthesis, Characterization and Photocatalytic Behavior of SiO2 @nitrized-TiO2 Nanocomposites Obtained by a Straightforward Novel Approach.

We report on the facile synthesis of SiO2 @nitrized-TiO2 nanocomposite (NST) by calcination of TiO2 xerogel with OctaAmmonium POSS® (N-POSS; POSS=polyhedral oligomeric silsesquioxanes). The as-obtained nanoporous mixed oxide is constituted by uniformly distributed SiO2 and nitrized-TiO2 , where the silica component is present in an amorphous state and TiO2 in an anatase/rutile mixed phase (92.1 % vs. 7.9 %, respectively) with very small anatase crystallites (3.7 nm). The TiO2 lattice is nitrized both at interstitial and substitutional positions. NST features a negatively charged surface with a remarkable surface area (406 m2 g-1 ), endowed with special adsorption capabilities towards cationic dyes. Its photocatalytic behavior was tested by following the degradation of standard aqueous methylene blue and methyl orange solutions under UV and visible light irradiation, according to ISO 10678:2010. For comparison, analogous investigations were carried out on a silica-free N-TiO2 , obtained by using NH4 Cl as nitrogen source.

Diastereoselective multicomponent synthesis and anti-HSV-1 evaluation of dihydrofuran-fused derivatives.

Enolizable 6-membered cyclic 1,3-dicarbonyls undergo an efficient and diastereoselective domino condensation/addition/heterocyclization reaction with arylaldehydes and phenacyl chloride, producing highly substituted dihydrofuran-fused derivatives. Ring size of the cyclic 1,3-dicarbonyls and the presence of at least one keto group are crucial to the reaction's success. The new compounds were evaluated in vitro for antiviral activity against herpes simplex virus type-1 (HSV-1). Interestingly, some of them appeared able to interfere with HSV-1 replication, without detection of cytotoxic effects.

Oxidative damage in human epithelial alveolar cells exposed in vitro to oil fly ash transition metals.

Among particulate matter emissions from combustion processes, oil fly ash (OFA) displays a marked oxidative and inflammogenic reactivity, due to the high content of bioavailable transition metals. In the present study, we evaluated the biological effects of an OFA water solution, composed of the transition metals Fe (57.5%), V (32.4%), and Ni (10.1%), in human epithelial alveolar cells (A549 line). The fluorimetric analysis by 2',7'-dichlorofluorescein showed a significant, dose- and time-dependent induction of intracellular reactive oxygen species (ROS) triggered by OFA metal components at subtoxic doses. The metal chelator deferoxamine and the radical scavenger dimethylsulfoxide attenuated the metal-induced generation of ROS. Confocal microscopy observations strengthened these findings and showed an intense cytoplasmic fluorescence with perinuclear thickenings in A549 cells, in the absence of morphological damage. Metal-induced generation of ROS was significantly correlated with a dose- and time-dependent DNA damage, as assessed by single cell gel electrophoresis (comet assay). Catalase was able to decrease dramatically DNA damage. Fluorimetric analyses by diphenyl-1-pyrenylphosphine showed a parallelism between generation of ROS and formation of lipid peroxides. The results obtained in the experiments evaluating the effects of individual metal solutions did not show any significant difference in DNA damage between Fe(III) and V(IV), but highlighted the higher capability of V(IV) to increase ROS in the cytoplasmic compartment. The different behavior of these two elements, confirmed by the weak Fe-induced lipid peroxidation, may be ascribed to the presence of Fe-binding proteins, such as ferritin, in the cytoplasm. Finally, Ni(II) had negligible effects on ROS production. On the whole, the results obtained in this study show the strong capability of transition metals adsorbed to OFA to cause widespread damage to biological macromolecules, and suggest potential health effects resulting from exposure to power plant emissions in industrialized sites.

Use of a glass residue in the removal of heavy metals from wastewater.

The extraction of silica from powdered glass cullet with an aqueous solution of sodium hydroxide has been proposed as an alternative to glass recycling aimed to the low temperature production of sodium silicates. The unextracted residue obtained after a counter current two-step extractive process at approximately 100 degrees C and room pressure is mainly made of calcium and sodium silicate and shows high porosity and a large surface area. We thought that it could be active as an agent for the removal of heavy metals from wastewater. In this paper the capacity of the unextracted residue of removing six metal ions (i.e., Cu2+, Ni2+, Zn2+, Cd2+, Pb2+ e Cr3+) was studied in a stirred batch reactor. The data obtained demonstrate that the removal of metal ions from wastewater is achieved with high capacity in a short time and their concentration is lowered under the legal limits without any appreciable influence from changes of physical and chemical conditions. Sodium and calcium ions take the place of heavy metals in water while pH keeps almost neutral. The exchange mechanism was identified.

Efficiency of a zeolitized pumice waste as a low-cost heavy metals adsorbent.

The unextracted residue obtained after a countercurrent two-step extractive process of silica from pumice lapillus, at 100 degrees C and room pressure, has been found mainly crystallized to the pseudo-cubic form typical of zeolite P. This residue could be active as a low-cost agent for the removal of heavy metals from wastewater. In this paper the removal capacity of six metallic cations (i.e. Cu(2+), Ni(2+), Zn(2+), Cd(2+), Pb(2+) and Cr(3+)) was studied in a stirred batch reactor. Results obtained showed that the removal of metal ions (100-500mgg(-1)) from wastewater is achieved in a short time and the concentration lowered under the legal limits. The adsorption mechanism mainly involves an ionic exchange between sodium ions from the solid phase and heavy metals in solution. However, if wastewater was accompanied by free acidity, it first should be neutralized to pH 4-5 to prevent zeolite destruction.