M. Burgard

Silver nitrate refining using supported liquid membranes

Abstract Supported liquid membranes (SLMs) containing linear polydendate or macrocyclic extractant carriers which transport silver nitrate are presented. The performance of these SLMs are discussed in terms of silver (I)/copper (II) transport selectivity. The influence of palladium (II) on the silver transport is also considered.

Extraction of gold and silver cyanide complexes through supported liquid membranes containing macrocyclic extractants

Developpement des techniques de recuperation des metaux precieux (or et argent) par des membranes liquides. Utilisation des composes macrocycliques pour la complexation en milieu basique des metaux

SOLVENT EXTRACTION OF THE RARE-EARTH METAL IONS BY A CONE-SHAPED CALDC[4]ARENE SUBSTITUTED AT THE LOWER RTM BY FOUR -CH2P(O)Ph2 LIGANDS

ABSTRACT The extraction properties of cone-5,11,17,23-tetra-t-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy)calix[4]arene (1) in 1,2-dichloroethane towards rare-earth metal ions at 25 °C have been investigated. The slope analysis showed a 1:1 metal/ligand ratio for the extracted species (La, Eu, Er and Y). The distribution coefficients increase with the polarity of the diluents : chloroform ≤ dichioromethane ≤ 1,2-dichloroethane ≤ nitrobenzene. In the competitive extraction of 11 rare-earth metal ions (La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y), ligand 1 exhibits higher extraction efficiency and a better separation factor than tri-n-octylphosphine oxide.

Recovery of silver nitrate by transport across a liquid membrane containing dicyclohexano 18 crown 6 as a carrier

Abstract The solvent extraction and transport through a bulk liquid membrane of silver nitrate from a copper nitrate medium by dicyclohexano 18 crown 6 (DC18C6) in dichloromethane takes place via the formation of the complex ion pair Ag(DC18C6)NO 3 in the organic phase. The selectivity of the transfer process characterises the semi-permeability of the liquid membrane, which is able to concentrate silver cations. Results show that the transport is well described by the two-film theory.

Size effect of complexing microcapsules on copper ion extraction

Abstract In a previous work [J. Microencapsulation, in press], polyamide microcapsules containing a poly(acrylic acid) gel as a macromolecular ligand (PAA-CAPS) with a mean diameter of 210 μm were prepared using an original two-step polymerization process combining interfacial polycondensation and radical polymerization in a water in oil inverse emulsion system. Extractions of many divalent cations were examined. In this work, we proposed to synthesise by the same process, smaller microcapsules with a mean diameter of 10 μm (PAA-μCAPS). Reference polyamide microcapsules, i.e. without ligand were also synthesized (μCAPS) and (CAPS) [J. Microencapsulation, in press]. Microcapsule wall thickness was evaluated by SEM and TEM observations of microcapsule cross-section cuts, microcapsule water content was determined by thermogravimetric experiments. Specific surface area and total volume of the pore of microcapsules were determined by BET method based on N2 adsorption/desorption. The comparison of the extractabilities and the stripping of Cu(II) into the various kind of microcapsules were examined.

Extraction of metal cations by polyterephthalamide microcapsules containing a poly(acrylic acid) gel

Polyterephthalamide microcapsules containing a poly(acrylic acid) gel as a macromolecular ligand (PAA-CAPS) were prepared using an original two step polymerization process in a water-in-oil inverse emulsion system. A polyamide microcapsule containing acrylic acid, initiator and cross-linking agent, is formed by interfacial polycondensation of terephthaloyl dichloride with hexamethylenediamine. In situ radical polymerization of the microcapsule core acrylic acid is initiated to obtain encapsulated poly(acrylic acid) gel. Reference polyamide microcapsules, i.e. without ligand (CAPS), were also synthesized. The mean diameter of synthesized microcapsules was 210 #181;m, and the microcapsule wall thickness was evaluated by SEM and TEM observations of microcapsule cross-section cuts. The microcapsule water content was determined by thermogravimetric experiments. The extractabilities of Cu(II), Ni(II), Co(II) and Zn(II) into PAA-CAPS were examined. The stripping of the various cations can be promoted in diluted hydrochloric acid solutions.

Multifunctional Calix[4]arenes Containing Pendant Amide and Phosphoryl Groups: Their Use as Extracting Agents and Carriers for Alkali Cations

The complexing, extracting and mobile carrier properties of the tetra(phosphine oxide)-calix[4]arene 1 and the hybrid diamide-di(phosphine oxide)-calix[4]arene 2 were studied. Both ligands give 1 : 1 complexes with alkali cations in THF as shown by the picrate method. 1H NMR experiments were run to follow encapsulation of sodium and potassium cations. The corresponding spectra indicate C2-symmetrical structure. The observed extraction orders of the alkali picrates were as follows K+>Rb+>Li+>Cs+>Na+ for 1 and Li+>Na+>K+>Rb++ for 2. Transport kinetics was analysed by means of a model which assumes pure diffusion and which allows the evaluation of mass transfer coefficients in all systems. These coefficients and their influences on the transport rate are discussed in terms of size of the transporting species in the liquid membrane.

Calix[4]arenes with Pendant Amide and Phosphine Oxide Functionalities: Use as Extractive Agents and Carriers for Silver (I) Ions

The solvent extraction properties towards Ag+ of5,11,17,23-tetra-tert-butyl-25,27-diX-26,28-bis(diphenylphosphinoylmethoxy)calix[4]arenes (X = CH2C(O)NEt2 (1), CH2P(O)Ph2 (2), CH3 (3), CH2C(O)Et (4))have been studied. Each ligand forms a 1 : 1 complex with silver(I). Ligand1, which bears two amide functionalities, is the most efficacious,emphasizing the crucial role played by the polar amide groups. The rate oftransport of AgNO3 through a bulk liquid membrane with this ligand ascarrier was shown to be superior to that of DC18C6, a structurally-relatedmulti-oxygen donor carrier. NMR and IR data suggest that Ag+ is coordinatedto each of the oxygen atoms in the ligand leading to an encapsulatedstructure [Ag ⊂ 1]+.

Étude vibrationnelle du complexe d'addition moléculaire du pentachlorure d'antimoine avec le dimethyl sulfoxyde

Abstract Infrared and Raman spectra of the complexes SbCl 5 -dimethyl sulphoxide (DMSO) and SbCl 5− -DMSO-d 6 , from 50 to 4000 cm −1 are reported. A normal coordinate analysis confirmed the assignments proposed on the hypothesis of C s symmetry for the complexes. Vibrational spectra of the SbCl 6 − anion have been used as models for discussing the perturbations of the antimony pentachloride molecule due to the coordination.

Synthesis and Extraction Properties of 1,3,5-O-trimethyl-2,4,6-tri-O-hydroxamic Acid p-tert-butyl Calix[6]arene

A calix[6]arene bearing three hydroxamic acid groups arranged in aC3 symmetry has been synthesized. Extraction properties towards transition metal ions are presented and compared with other proton-ionizable related calix[6]arenes and with a monomeric hydroxamic acid analog.