1,720,984 research outputs found
Electrokinetic Remediation and in-situ iron barrier generation
No full textElectrokinetic remediation (EKR; simply put, moving things with electricity) uses low voltage DC current to control the migration (Figure 1) of contaminants in porous media and remove or degrade them. We have previously demonstrated that ex-situ EK techniques can treat plutonium-contaminated wastes at the AWE Aldermaston site1, and the technique is widely applied at scale for the destruction of substrates (soils, etc.) contaminated with organic pollution.Here, we present our work on using EKR to remediate a range of contaminated substrates, in controlled remediation of real Sellafield materials by growth of in-situ iron barriering
Supplementary spectroscopic data for the paper Complexes of Group 2 dications with soft thioether- and selenoether-containing macrocycles.
No full textSupplementary spectroscopic data for the paper Complexes of Group 2 dications with soft thioether- and selenoether-containing macrocycles.
William Levason, David Pugh, Jamie M. Purkis and Gillian Reid
Dalton Transactions DOI: 10.1039/c6dt00808a</span
Complexes of Group 2 dications with soft thioether- and selenoether-containing macrocycles
No full textA new route to cationic complexes of Mg, Ca, Sr and Ba with 18-membered ring O4S2, O4Se2 and O2S4 donor macrocycles from metal acetonitrile complexes with weakly coordinating [BArF]? anions is described. The precursors used were [M(MeCN)x][BArF]2 (M = Mg, x = 6; M = Ca, x = 8) and [M?(acacH)(MeCN)5][BArF]2 (M? = Sr or Ba). Reaction of these with the heterocrowns, [18]aneO4S2 (1,4,10,13-tetraoxa-7,16-dithiacyclooctadecane), [18]aneO4Se2 (1,4,10,13-tetraoxa-7,16-diselenacyclooctadecane) or [18]aneO2S4 (1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane) in anhydrous CH2Cl2 solution gave [M(heterocrown)(MeCN)2][BArF]2 for M = Mg, Ca or Sr, whilst the larger Ba forms [Ba(heterocrown)(acacH)(MeCN)][BArF]2. The complexes have been characterised by microanalysis, IR, 1H and 13C{1H} NMR spectroscopy. X-ray crystal structures are reported for [Ca([18]aneO2S4)(MeCN)2][BArF]2, [Ca([18]aneO4Se2)(MeCN)2][BArF]2, [Sr([18]aneO4S2)(MeCN)2][BArF]2, and [Sr([18]aneO4Se2)(MeCN)2][BArF]2 which contain 8-coordinate metal centres with trans-nitrile ligands and ?6-heterocrowns, and for the 9-coordinate [Ba([18]aneO4Se2)(acacH)(MeCN)][BArF]2. Adventitious hydrolysis of the magnesium complexes in solution results in six-coordinate complexes, [Mg(?3-[18]aneO4Se2)(OH2)2(MeCN)][BArF]2 and [Mg(?3-[18]aneO4S2)(OH2)2(MeCN)][BArF]2, whose structures were determined. X-ray crystal structures are also reported for [Mg(MeCN)6][BArF]2, [M(MeCN)8][BArF]2 (M = Ca, Sr) and [Ca(18-crown-6)(MeCN)2][BArF]
Controlled photocatalytic hydrocarbon oxidation by uranyl complexes
Full text linkControlled, photocatalytic C−H bond activations are key reactions in the toolkits of the modern synthetic chemist. While it is known that the uranyl(VI) ion, [UVIO2]2+, the environmentally dominant form of uranium, is photoactive, most literature examines its luminescent properties, neglecting its potential synthetic utility for photocatalytic C−H bond cleavage. Here, we synthesise and fully characterise an air‐stable and hydrocarbon‐soluble uranyl phenanthroline complex, [UVIO2(NO3)2(Ph2phen)], UPh2phen, and demonstrate that it can catalytically abstract hydrogen atoms from a variety of organic substrates under visible light irradiation. We show that the commercially available parent complex, uranyl nitrate ([UVIO2(NO3)2(OH2)2]⋅4H2O; UNO3), is also competent, but from electronic spectroscopy we attribute the higher rates and selectivity of UPh2phen to ligand‐mediated electronic effects. Ketones are selectively formed over other oxygenated products (alcohols, etc.), and the catalytic oxidation of substrates containing a benzylic C−H position is particularly improved for UPh2phen. We also show uranyl‐mediated photocatalytic C−C bond cleavage in a model lignin compound for the first time
Electrokinetic remediation for nuclear site decommissioning - the UK's TRANSCEND Consortium – 21238
No full textElectrokinetic Remediation, EKR, is an environmental remediation technology that uses electricity to remove pollutants from contaminated materials. It is a flexible and low-energy (< 1 V.cm-1) technique, that operates effectively in low permeability substrates (clayey soils, cements, etc.) which are often difficult to remediate by conventional means (e.g. soil washing, pump-and-treat). It can be combined with renewable power inputs and operate in-situ, providing effective, safe and sustainable solutions in which worker exposure to hazardous materials is minimized while high remediation efficiencies are retained. However, EKR is limited mostly to the laboratory or pilot scale for nuclear industry applications, with reliable, meter-plus scale studies in real operating environments still lacking.
Here, we discuss EKR and its potential uses at nuclear sites. We begin by summarizing the key advantages offered by EKR over other, conventional remediation methods and, from this, review how EKR, singly or in combination with other technologies, can be or has been applied practically. We illustrate this using real examples at selected nuclear sites of international importance. Finally, we examine perspectives on tools to help the decision-making process for remediation at active nuclear sites, and how these tools could be used to support practical deployment of EKR for nuclear site decommissioning
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