Transformation/dissolution characterization of tungsten and tungsten compounds for aquatic hazard classification
The transformation/dissolution protocol (T/DP) for metals and sparingly soluble metal compounds was applied to determine the transformation/dissolution (T/D) characteristics of yellow tungsten trioxide, WO3; blue tungsten oxide, WOx, x taken as 2.9; tungsten disulphide, WS2; tungsten metal, W; 3 samples of tungsten carbide, WC; sodium tungstate, Na2WO4 · 2H2O; ammonium paratungstate (APT), (NH4)10(H2W12O42) · 4H2O; and ammonium metatungstate (AMT) (NH4)6(H2W12O40) · 3H2O. The T/D data were used to derive aquatic hazard classification outcomes under the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS) and European Union Classification, Labelling and Packaging of Substances and Mixtures (EU CLP) schemes by comparing the data with selected acute and chronic ecotoxicity reference values (ERVs) of 31 and 3.37 mg W/L, respectively. In addition to the concentration of total dissolved tungsten (W), the T/D solutions were analyzed for the concentration of the tungstate anion, because speciation can be an important factor in establishing the ecotoxicity of dissolved metals. Results show that the tungstate anion was the predominant W‐bearing species in solution for all substances examined at pH 6 and 8.5. It was found that the 100 mg/L loadings of both the yellow WO3 and the blue WOx exceeded the 31 mg/L acute ERV, so they would classify as Acute 3‐Chronic 3 under the UN GHS scheme but they would not classify under the EU CLP. An effect of pH on the reactivity of the W metal was observed with 3% and 16% W dissolution at pH 6 and 8.5, respectively. Tungsten metal would not classify under either the UN GHS or EU CLP schemes nor would the WS2. The WCs were the least reactive in terms of the 1% or less dissolution of the contained W at pH 6. A critical surface area for WC was calculated. The sodium tungstate, APT and the AMT all yielded, at pH 8.5, total dissolved W concentrations that would result in UN GHS Acute 3‐Chronic 3 classifications. Integr Environ Assess Manag 2018;14:498–508. © 2018 Her Majesty the Queen in Right of Canada. Integrated Environmental Assessment and Management © 2018 SETAC
WS2 as highly active co-catalyst for the regeneration of Fe(II) in the advanced oxidation processes.
The greatest constraint in the advanced oxidation processes involved Fe(II)/PMS was the low utilization of Fe(II) and PMS. In the present study, the co-catalytic effect of WS2 on the Fe(II)/PMS system for the degradation of organics was investigated. In the presence of WS2, Fe(III) was reduced to Fe(II) during the reaction and resulted in improved decomposition of PMS as well as the degradation of 4-chloriphenol (4-CP). The decomposition rate of PMS and degradation efficiency of 4-CP were 10% and 25% in the Fe(II)/PMS process, while the efficiencies respectively increased to 99% and 100% in the WS2 assisted Fe(II)/PMS system. The degradation of 4-CP was completed via the free radical pathway and SO4•- played a more important role than other active species. Low concentration of inorganic ions such as Cl- and HCO3- exhibited irrelevant effect while humic acid showed significant suppression on the WS2/Fe(II)/PMS system. Additionally, characterization and recycle results implied that WS2 maintained a good stability during the co-catalytic processes.
Women's health in prison: urgent need for improvement in gender equity and social justice.
The needs of women held in detention have received little attention and con-tinue to be neglected by health systems and prison authorities. One reason for this, too readily accepted until now, is that women prisoners are a clear minor-ity group within prisons all over the world. It is only recently that attention has been drawn to the fact that a minor-ity status does not justify the widespread ignorance of women’s basic rights and the considerable gender insensitivity still dominating criminal justice systems.In Europe alone, there are about 100 000 women and girls in prison.