Jacques Foos

Cloud point extraction : An alternative to traditional liquid-liquid extraction for lanthanides(III) separation

Cloud point extraction (CPE) was used to extract and separate lanthanum(III) and gadolinium(III) nitrate from an aqueous solution. The methodology used is based on the formation of lanthanide(III)-8-hydroxyquinoline (8-HQ) complexes soluble in a micellar phase of non-ionic surfactant. The lanthanide(III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud point temperature (CPT). The structure of the non-ionic surfactant, and the chelating agent-metal molar ratio are identified as factors determining the extraction efficiency and selectivity. In an aqueous solution containing equimolar concentrations of La(III) and Gd(III), extraction efficiency for Gd(III) can reach 96% with a Gd(III)/La(III) selectivity higher than 30 using Triton X-114. Under those conditions, a Gd(III) decontamination factor of 50 is obtained.

Selective Strontium Removal from a Sodium Nitrate Aqueous Medium by Nanofiltration - Complexation

In aqueous medium, selective complexation increases the ionic separation by nanofiltration. The combination of nanofiltration and complexation can be applied to the nuclear effluents treatment. To separate radioelements from a sodium salt medium, poly(acrylic acid) is associated to the FILMTEC NF 70 membrane. Effects of transmembrane pressure, pH, ligand concentration and ionic strength on salts retention are described, and the complexation constants are estimated. Finally, to reach the objectives, a strontium two-stages concentration by nanofiltration-complexation with a control of retentate salinity is investigated in a nonactive solution case.

Lipophilic polythiamacrocycles as palladium extracting agents

Abstract Six new lipophilic thiacrown ethers ( 1 – 6 ), abbreviated as 2-octyl-9S3, 2-octyl-10S3, 2-octyl-12S4, 6-octyl-14S4, 3-octyl-16S4 and dioctyl-18S6, were synthesized starting from different dithiols and dihalides. Cs2CO3 is used for the cyclizations. The extraction behavior of palladium (II) from nitric acid media with these reagents in chloroform has been studied in terms of extraction equilibrium constants Kex. The influence of parameters such as lipophilicity brought by alkyl chains, macrocyclic cavity size and number of sulfur donor atoms on the extraction behavior was investigated.

Regioselective synthesis of N-functionalized 12-membered azapyridinomacrocycles bearing trialkylcarboxylic acid side chains

Abstract Selective protection of primary amine moieties of diethylenetriamine by 2-nitrophenylsulfonyl chloride followed by alkylation of the central N atom generates functionalized disulfonamide building blocks. When reacted with 2,6-bis(bromomethyl)pyridine following the Richman–Atkins methodology, such compounds yield the corresponding pyridine-containing azamacrocycles. Smooth removal of the N-sulfonyl groups provides versatile azamacrocyclic intermediates with transannular secondary amine functions. Subsequent N-alkylation regioselectively leads to tri N-functionalized 12-membered azapyridinomacrocycles bearing a sequence of N-acetate and N-propionate side chains.

Selective Separation of Lanthanides with Phenolic Resins: Extraction Behavior and Thermal Stability

Catechol, resorcinol, and their admixtures with 8-hydroxyquinoline were converted into polymeric resins by alkaline polycondensation with formaldehyde. The resins were characterized by FTIR spectroscopy, moisture regain, ion-exchange capacity, and distribution coefficient (D) for Eu3+. Thermogravimetric analysis of the polymer samples was studied, and the effect of the sorption of metal ions on their thermal stability was evaluated. Complexation of Eu3+ to the resins was modeled based on metal ion charge neutralization. The selective uptake of Eu3+ from aqueous solutions containing La3+ was investigated, and the ionoselectivities of the resins were compared. The incorporation of 8-hydroxyquinoline in the molecular matrix of the phenolic resins is shown to exert a significant influence upon the competitive sorption of La3+ and Eu3+, leading to their intragroup separation. The separation factors obtained by phenolic ion-exchange resins from aqueous solutions indicate ion-specific resins can be developed for the specific separation of actinide ions from nuclear waste.

Radiolytic products study of dicyclohexano-18-crown-6, a selective extractant for nuclear fuel reprocessing

The radiolytic products of the DCH18C6 obtained after γ-irradiation have been determined, and the seven main structures have been separated and analyzed. The radiolytic product yields range from about 0.01 to nearly 0.3 molecules per 100 eV absorbed by the DCH18C6 at an energy of 3290 kGy. From the viewpoint of radiation decomposition rate, the DCH18C6 presents a considerable resistance and its radiolytic products have little or no extraction power.

An efficient synthesis of pyridine containing triaza-macrocyclic triacetate ligand and luminescence properties of its europium(III) complex

Reaction of diethylenetriamine with 2-nitrobenzenesulfonyl chloride leads to an activated and protected compound that could be cyclized to N-protected aza-macrocycle. After a smooth deprotection step, the macrocycle was alkylated with chloroacetic acid leading to the pyridine containing triaza-macrocycle 1 in good yield. The luminescence properties of its Eu3+ complex were examined in aqueous solution.

New extractant for selective recovery of palladium from high level radioactive waste

Use of di- or tri-thioether instead monothioether permits to increase both efficiency and selectivity of the extraction of palladium. This selectivity allows the separation of palladium contained in nuclear fuel reprocessing solution in a single step.

Cloud-point extraction for selective removal of Gd(III) and La(III) with 8-hydroxyquinoline

Abstract: A less-common extraction procedure, cloud-point extraction, is used with a lipophilic chelating agent (8-hydroxyquinoline) to extract and separate lanthanum(III) and gadolinium(lll) ions from an aqueous solution. Surfactant solutions are used in conjunction with 8-hydroxyquinoline to form a lanthanide complex that is extracted into the micellar phase at a temperature above the cloud-point temperature. The structure of the lipophilic part of the nonionic surfactant, the chelating agent-metal molar ratio, and the cloud-point temperature are identified as factors determining the extraction efficiency and selectivity. With Triton X-114, a selectivity higher than 30 and a decontamination factor of 50 for Gd(IlI) indicate that micelle-mediated cloud-point extraction is promising for the specific separation of actinide ions from nuclear waste. Finally, a microwave procedure is proposed to decrease the duration of the experiment to less than 6 min.

Selective extraction of palladium from acidic nitrate solutions with thiamacrocycles-synergized dinonylnaphthalenesulfonic acid systems

Thiamacrocycles-synergized sulfonic acid extraction systems have been studied for removing traces of palladium from nitric acid solutions. The influence of the concentration of nitric acid, HDNNS, and thiamacrocycle were studied. Then different thiamacrocycles, with various cavity size and with or without substituent were evaluated. Influences on the extraction and stripping behavior is discussed.