VS2 and its doped composition: Catalytic depolymerization of alkali lignin for increased bio-oil production.

VS2 spheres and VS2 sheets with doped compositions (Mo, Ag and graphite) were successfully prepared by one-step hydrothermal method and characterized by different techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption isotherms. Catalysts were applied for the depolymerization of alkali lignin. VS2 spheres exhibited lower yield of degraded lignin and bio-oil than those with VS2 sheets and VS2 flowers heated to 250 °C and held for 1.5 h with 2.0 MPa H2. The catalytic depolymerization performance was markedly affected by the dopant in the VS2 sheets, with the highest degraded lignin yield of 81.22%, achieved over 5 wt% Ag-VS2 at 290 °C under 2.0 MPa H2 for 1.5 h, yielding 61.23% bio-oil. The VS2-based catalysts show excellent selectivity in the interruption of the lignin structure and target production of bio-oil. The bio-oil showed that the relevant contents of a phenolic-type compound changes significantly according to the dopant in the VS2 catalyst.

Respirable Uranyl-Vanadate-Containing Particulate Matter Derived From a Legacy Uranium Mine Site Exhibits Potentiated Cardiopulmonary Toxicity.

Exposure to windblown particulate matter (PM) arising from legacy uranium (U) mine sites in the Navajo Nation may pose a human health hazard due to their potentially high metal content, including U and vanadium (V). To assess the toxic impact of PM derived from Claim 28 (a priority U mine) compared with background PM, and consider the putative role of metal species U and V. Two representative sediment samples from Navajo Nation sites (Background PM and Claim 28 PM) were obtained, characterized in terms of chemistry and morphology, and fractioned to the respirable (≤ 10 µm) fraction. Mice were dosed with either PM sample, uranyl acetate, or vanadyl sulfate via aspiration (100 µg), with assessments of pulmonary and vascular toxicity 24 h later. Particulate matter samples were also examined for in vitro effects on cytotoxicity, oxidative stress, phagocytosis, and inflammasome induction. Claim 28 PM10 was highly enriched with U and V and exhibited a unique nanoparticle ultrastructure compared with background PM10. Claim 28 PM10 exhibited enhanced pulmonary and vascular toxicity relative to background PM10. Both U and V exhibited complementary pulmonary inflammatory potential, with U driving a classical inflammatory cytokine profile (elevated interleukin [IL]-1ß, tumor necrosis factor-α, and keratinocyte chemoattractant/human growth-regulated oncogene) while V preferentially induced a different cytokine pattern (elevated IL-5, IL-6, and IL-10). Claim 28 PM10 was more potent than background PM10 in terms of in vitro cytotoxicity, impairment of phagocytosis, and oxidative stress responses. Resuspended PM10 derived from U mine waste exhibit greater cardiopulmonary toxicity than background dusts. Rigorous exposure assessment is needed to gauge the regional health risks imparted by these unremediated sites.

Determination of volatile and non-volatile nickel and vanadium compounds in crude oil using electrothermal atomic absorption spectrometry after oil fractionation into saturates, aromatics, resins and asphaltenes.

In recent work, it has been shown that electrothermal atomic absorption spectrometry (ET AAS) can be used to differentiate between volatile and non-volatile nickel and vanadium compounds in crude oil. In the present work, the distribution of these two groups of compounds over different fractions of crude oil was investigated. For this purpose two crude oil samples were separated in two steps: firstly, the asphaltenes were precipitated with n-heptane, and secondly, the maltenes were loaded on a silica column and eluted with solvents of increasing polarity. The four fractions of maltenes eluted from silica column were: F1, saturated and light aromatics; F2, polyaromatics; F3, resins; and F4, polar compounds. Fractions F1 and F2 were further investigated using gas chromatography, and all fractions were characterized by CHN analysis, confirming the increase of aromatics in the fractions 2, 3, 4 and asphaltenes. For the determination of Ni and V by ET AAS, oil-in-water emulsions were prepared. The speciation analysis was carried out measuring without chemical modifier (stable compounds) and with 20 microg palladium (total Ni and V) and the volatile fraction was calculated by difference. The limits of detection were 0.02 microg g(-1) and 0.06 microg g(-1), for Ni and V, respectively, based on an emulsion of 2g of oil in 10 mL. The volatile species of Ni and V were associated with fractions F3 and F4, while only thermally stable Ni and V was precipitated in part together with the asphaltenes.