1,720,974 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
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]
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
Enhanced electrokinetic remediation of nuclear fission products in organic-rich soils
No full textElectrokinetic remediation, EKR, is technology that circumvents the traditional challenges faced by many existing remediation technologies in low permeability substrates. Cheap, non-toxic additives such as KCl may further help EKR remediation efficiency by increasing electrolyte strength; their use has been reported in concretes, but not soils. Here, we investigate the efficiency of low-energy EKR (with and without electrolyte additives) in the mobilisation of radiostable Cs and Sr in a clayey, organic-rich soil. Soil maturation time and voltage are key factors in determining success of EKR. Although Cs and Sr are effectively mobilised (up to 317 and 330%, respectively) in the electric field in our soils (determined by XRF), maturation time (7 or 45 days) and voltage (15 or 20 V) are key to successful remediation using EKR. We more broadly show that understanding speciation and the local ionic environment of relevant radionuclides within entrained matrices is vital to effective application of this technology.</p
Electrokinetic remediation of radionuclide contaminated land
No full textElectrokinetic Remediation, EKR, is an environmental remediation technology that uses electricity to remove pollutants from contaminated materials; Figure 1. 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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