Steady state foams made of a pH sensitive surfactant, nonaoxyethylene oleylether carboxylic acid, with ion complexing properties was studied using small angle neutron scattering (SANS). The effect of pH variation and salt addition on the foam film thickness was investigated and discussed in terms of the influent parameters stabilizing the foam such as surface properties and electrostatic effects determined by tensiometry and zeta potential measurements. The decrease in the film thickness by adding mono (Na(+)) and divalent (Ca(2+)) salts is classically explained by screening of the double layer in foam films (transverse interactions). On the contrary, addition of acid or complexing ion (Nd(3+)) results in an increase in the film thickness and can be analyzed in terms of cohesive forces between surfactants at the liquid/gas interface (lateral interactions). pH and specific salt effects revealed that foams produced by nonaoxyethylene oleylether carboxylic acid are of interest in the potential use of this surfactant in ion separation process.
Fundamental knowledge about plutonium intrinsic colloids is a key issue for the prediction of plutonium transport and release rates in the environment. Recent studies demonstrated that the particle size and...
A fine tuning of the electrostatic interactions between Cu-Prussian blue analog nanoparticles and a pH responsive surfactant for an efficient and low-footprint caesium extraction process.
A series of phosphonate-functionalized task-specific ionic liquids (TSILs) have been synthesized and studied for selective extraction of tantalum from a sulfuric acid medium. The results described here show that high distribution coefficient values can be achieved for the selective separation of tantalum (Ta). Such a system can be used as an alternative to TBP for the separation and purification of tantalum by solvent extraction.
The unique properties of tantalum (Ta) have resulted in its important usage to supply the capacitors and semiconductor production for electronics devices. Technological needs make Ta economically and strategically important to industrialized countries. Among different possibilities, the recovery of Ta from industrial waste and end-of-life products represents an economically attractive and viable approach, which aims at decreasing the environmental footprint in general. Currently, there is a lack of an efficient Ta recycling strategy from e-waste. In the present work we studied the possibility to use pure ionic liquids such as N-butyl-N-ethylpiperidinium bis(trifluoromethylsulfonyl)imide (EBPiP-NTf2), N-octyl-N-ethyl-piperidinium bis(trifluoromethylsulfonyl)imide (EOPiP-NTf2) as extracting media. Ionic liquids were used as alternative solvents that will have limited impact on health and environment compared to traditional organic solvents. We propose an eco-friendly process for the extraction and stripping of tantalum from sulfuric acidic medium that may come from of the dissolution of bottom ash and by-products of industrial activities, as well as from secondary sources such as waste electrical and electronic equipment (WEEE). The extractability of ILs for Ta was demonstrated, and under the experimental conditions, the more promising properties have been highlighted for EOPiP-NTf2. Back extraction of Ta from the loaded ionic liquid phase was also examined and showed that quantitative recovery of metal was possible using water, allowing thus to recover the ionic liquid and the Ta. Considering the efficiency as well as greener aspects of the process, due to the use of ionic liquids which loss is highly limited in aqueous phase, a more "sustainable process" is proposed in comparison to organic solvents and previous ionic liquid based extraction system useful for the selective recovery of tantalum.
The size and shape of a water-soluble hexanuclear plutonium cluster were probed by combining synchrotron small-angle X-ray scattering (SAXS) and extended X-ray absorption fine structure (EXAFS). A specific setup coupling both techniques and dedicated to radioactive samples on the MARS beamline endstation at Synchrotron SOLEIL is described. The plutonium hexanuclear cores are well stabilized by the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid ligands and this allows a good evaluation of the setup to probe the very small plutonium core. The results show that, in spite of the constrained conditions required to avoid any risk of sample dispersion, the flux and the sample environment are optimized to obtain a very good signal-to-noise ratio, allowing the detection of small plutonium aggregates in an aqueous phase. The structure of the well defined hexanuclear cluster has been confirmed by EXAFS measurements in solution and correlated with SAXS data processing and modelling. An iterative comparison of classical fit models (Guinier or sphere form factor) with the experimental results allowed a better interpretation of the SAXS signal that will be relevant for future work under environmentally relevant conditions.
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