Laurent Dupont

Metal ions binding onto a lignocellulosic substrate extracted from wheat bran: a NICA-Donnan approach

In this study ion binding to solid organic matter was investigated. We used the NICA-Donnan model to describe the interaction between Cu(II), Pb(II), and Cd(II) ions and a lignocellulosic substrate extracted from wheat bran. Such a material represents a very cheap and flexible substrate, which can be used as a natural filter to remove toxic metal ions from industrial effluents or applied in the decontamination and rehabilitation of abandoned industrial sites. Moreover, such a material also represents a very simple model of natural organic matter derived from lignin and cellulose, for which there is now a lack of thermodynamic data as far as their interaction with toxic metal ions is concerned. Experimental results were obtained in various conditions of pH and ionic strength. In our modeling, we used the acidity constants and the concentration of sites that were determined in a previous work. The parameters deduced from the NICA-Donnan model were also compared to thermodynamic data available for other cases of natural organic matter, mainly humic substances.

Aqueous Chemistry of Zirconium(IV) in Carbonate Media

The interactions between carbonate ions and zirconium oxychloride are studied by potentiometry, dialysis, and 13C- and 17O-NMR spectroscopy in aqueous media. The nature of the soluble carbonatohydroxo complexes depends on the proportions of hydrogencarbonate and carbonate ions in solution before the addition of zirconium oxychloride. Carbonate media lead to polynuclear entities containing no more than two complexed carbonate ions per Zr4+. The presence of hydrogencarbonate favors the formation of less condensed and more carbonated complexes such as [Zr(CO3)4]4−. The polycondensation degree of the species decreases when the number of carbonates linked per Zr4+ increases. In all complexes, the carbonate is bidentate, and the metal atoms are linked via hydroxo bridges. The complexation of carbonate with Zr4+ occurs for a total carbonate concentration higher than 0.1M. Consequently, in natural medium, the speciation of this metal is governed only by the formation of hydroxo complexes.

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) complexes with lactamides: solution and solid state studies

Three functionalized ligands, S(−)-N-(pyridin-2-ylmethyl)lactamide (pml), S(−)-N-(2-dimethylaminoethyl)lactamide (dmael) and S(−)-N-(3-dimethylaminopropyl)lactamide (dmapl), were synthesized by the aminolysis of S(−)-methyl lactate with the corresponding primary amines. Their protonation constants and the stability constants of the chelates formed with copper(II) were determined by potentiometry. In all cases, we detected the formation of CuLH−1+, CuLH−2 and CuLH−3− species (Lu2006=u2006free ligand). The copper(II) complexes prepared in the solid state were characterized by IR and UV-visible spectroscopies. The crystal structure of [Cu(pmlH−1)X] n (Xu2006=u2006Cl, Br) shows that copper(II) is bound to the pyridyl and the deprotonated amidic nitrogen atoms, as well as to the oxygen atom of the hydroxyl group, which leads to a mono-chelated compound. The geometry around Cu2+ is square pyramidal.

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.

Synthesis, physico-chemical properties and complexing abilities of new amphiphilic ligands from d-galacturonic acid

This paper describes a convenient and efficient synthesis of new complexing surfactants from d-galacturonic acid and n-octanol as renewable raw materials in a two-step sequence. In the first step, simultaneous O-glycosidation-esterification under Fischer conditions was achieved. The anomeric ratio of the products was studied based on the main experimental parameters and the activation mode (thermal or microwave). In the second step, aminolysis of the n-octyl ester was achieved with various functionalized primary amines under standard thermal or microwave activation. The physico-chemical properties of these new amphiphilic ligands were measured and these compounds were found to exhibit interesting surface properties. Complexing abilities of one uronamide ligand functionalized with a pyridine moiety toward Cu(II) ions was investigated in solution by EPR titrations. A solid compound was also synthesized and characterized, its relative structure was deduced from spectroscopic data.

Coordination Mode and Kinetic Behavior of the Tetracarbonatozirconate Ion

by Anne Veylanda), Jean Rimbaulta)*, Laurent Duponta), Jean-Claude Pierrarda), Michel Aplincourta), SteÂphane Bourgb), Jean-Marc Nuzillardb), and Jean-Francois Angiboustc) a) GRECI, UFR des Sciences Exactes et Naturelles, Universite de Reims Champagne-Ardenne, BP 1039, F-51687 Reims Cedex 2 b) Laboratoire de Pharmacognosie UPRESA 6013, Universite de Reims Champagne-Ardenne, BP 1039, F-51687 Reims Cedex 2 c) Laboratoire de Spectroscopie BiomoleÂculaire, Universite de Reims Champagne-Ardenne, BP 1039, F-51687 Reims Cedex 2

Investigation of the tetracarbonatozirconate ion by electrospray mass spectrometry in aqueous media

Abstract Reported here is the study of zirconium (IV) aqueous solutions in carbonate media by electrospray ionisation mass spectrometry (ESI–MS). Spectra analysis lead to consider the existence in the spray of the initial pseudomolecular labile species [Zr(CO 3 ) 4 (HCO 3 )] 5− , x H + , (6− x ) K + (or Na + ). The existence of this species confirms the associative exchange mechanism of carbonate ions with [Zr(CO 3 ) 4 ] 4− ion.

Syntheses, equilibrium, and structural studies of copper(II) and nickel(II) complexes with a tripodal alanine-based ligand

A heptadentate ligand, tris[(L)-alanyl-2-carboxamidoethyl]amine (H3trenala), has been synthesized as its tetrahydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Mononuclear species with protonated, neutral, or deprotonated forms of the ligand, [Cu(H5trenala)]4+, [M(H4trenala)]3+, [M(H3trenala)]2+, [M(H2trenala)]+, and [M(Htrenala)] (Mu2009=u2009Cu2+ and Ni2+) have been detected in all cases, while only Cu2+ gives dinuclear [Cu2(H2trenala)]2+, [Cu2(Htrenala)]2+, [Cu2(trenala)]+, and [Cu2(trenala)(OH)] species. Two dinuclear copper(II) complexes have been prepared and characterized by spectroscopic techniques (IR, UV-Vis, mass electro-spray) and thermogravimetric analysis.

Thermodynamic and spectroscopic studies of Cu(II) and Ni(II) complexes with a new proline–threonine dipeptide ligand

The interactions between a new proline-threonine dipeptide ligand with two metallic cations were investigated in aqueous solution. The metallic cations studied were the copper(II) and the nickel(II), which are involved in many biological processes. The combination of potentiometry, UV-visible spectrophotometry, EPR, and mass spectrometry was used to determine the formation constants of the complexes and their structure in solution. The complexation sites were identified using electronic absorption and EPR spectroscopies. Copper complexes were obtained as square planar or square pyramidal mononuclear species, whereas nickel complexes were obtained as dinuclear species with an octahedral geometry.