Stéphanie Boudesocque

Extraction of Metal Ions with Task Specific Ionic Liquids: Influence of a Coordinating Anion

Hydrophobic ionic liquids (ILs) were generated by association between a cationic ester derivative of betaine and bis(trifluoromethylsulfonyl)imide (Tf2N−) or dicyanamide (Dca−) anions. Extraction of Cu(II), Ni(II), Pb(II), and Cd(II) from water was performed with these ILs at room temperature. The use of Dca− anion greatly enhances the extraction efficiency of IL phase towards metal ions extraction. The metal could be back-extracted from the ionic liquid phase with aqueous EDTA solutions. The metal extractability of the ionic liquid after the back-extraction is equivalent to that of the fresh mixture showing that ionic liquid can be reused for several extraction and back-extraction cycles.

Copper(II) influence on flumequine retention in soils: macroscopic and molecular investigations.

The coadsorption of flumequine (fluoroquinolone antibiotic) and copper(II) on a alkaline soil sample (collected from the Champagne-Ardenne region, France) was studied at macroscopic and molecular scales by means of batch experiments and X-ray absorption spectroscopy. The retained antibiotic amount onto the soil surface increases (from 2- to >20-fold) with the copper concentration due to the formation of a Cu(II)-flumequine ternary surface complex, which leads to the accumulation of flumequine into soils. Flumequine can be classified at environmentally relevant pH values as a slow-mobile compound in soils and a very slow-mobile compound in the presence of copper, even at relatively low concentrations.

Efficient extraction of gold from water by liquid–liquid extraction or precipitation using hydrophobic ionic liquids

Extraction of tetrachloroaurate or tetrabromoaurate anions has been carried out using several ionic liquids bearing trialkyl(2-ethoxy-2-oxoethyl)ammonium (alkyl group = C2H5 [EtGBOEt+], n-C3H7 [PrGBOEt+] or n-C4H9 [BuGBOEt+]) cations and halide (Cl− or Br−), bis(trifluoromethanesulfonyl)imide (Tf2N−) and dicyanamide (Dca−) anions. The removal of gold anionic moieties from water was first studied by mixing aqueous solutions containing gold complexes and water soluble bromide ionic liquids. This led to the formation of a solid precipitate corresponding to a hydrophobic ionic liquid based on a tetrahalogenoaurate anion. Liquid–liquid extraction of anionic gold complexes using hydrophobic ionic liquids was also investigated.

Sorption of the Herbicide Terbumeton and its Metabolites onto Soils. Influence of Copper(II)

Environmental Context.Agrochemicals have contributed greatly to modern agriculture, allowing better yields and lower costs. However, their extensive use has led to frequent contamination of underground and surface water. A better knowledge of the fate of pesticides from the sprayer to the water that would take into account the diversity of the physical and chemical properties of the various molecules and environmental conditions should help in the challenge of protecting and restoring natural water quality. Abstract.The intensive use of terbumeton (N-(1,1-dimethyl)-N′-ethyl-6-methoxy-1,3,5-triazine-2,4-diamine) has resulted in its widespread presence, together with its main metabolites, in surface- and groundwater. To estimate the fate of these compounds, their adsorption and desorption properties were studied in vineyard soils. The values of the organic carbon normalized adsorption coefficient (KOC) for terbumeton (34.6 and 39.2 L g−1) were significantly higher than those of its metabolites (between 6.8 and 21.1 L g−1). Terbumeton exhibited a higher adsorption capacity and a lower desorption potential as compared with the metabolites. An important hysteresis was observed in all cases. The Freundlich isotherms exhibited a linear shape, which was interpreted as non-specific interaction. The influence of copper(II), a ubiquitous metal cation in vineyard soils, on pesticide sorption was also studied. Copper significantly decreased the amount of adsorbed terbumeton when present in a high concentration (2 ×10−4 M).

Use of dicyanamide ionic liquids for extraction of metal ions

Hydrophobic ionic liquids (ILs) were generated by association between tetraalkylammonium cations and dicyanamide (Dca−) anion. Extraction of Cu(II), Ni(II), Pb(II) and Cd(II) from water was then performed using these ILs at room temperature. The use of a coordinating Dca− anion allows high extraction yields for copper and cadmium to be obtained. The extraction mechanism of Cu(II) has been studied by the determination of the concentration of the organic cation released upon extraction and of the concentrations of counter ions co-extracted. Our results show that the extraction mechanism proceeds via a mixed process involving both cation exchange and ion-pairing, the proportions of which depend upon the nature of the anion and, more precisely, upon its position in the Hofmeister series. The coordination of Cu(II) in ionic liquid phase was followed by UV-vis and EPR spectroscopies.