Modeling of gadolinium recovery from nitrate medium with 8-hydroxyquinoline by emulsion liquid membrane.
The extraction equilibrium of Gd(III) from nitrate medium by 8-hydroxyquinoline (HOX) in toluene was studied. Liquid-liquid investigations were first carried out. Based on the equilibrium results, the extraction of Gd(III) from aqueous nitrate medium into an emulsion liquid membrane system (ELM) containing 8-hydroxyquinoline in toluene as extractant, HNO(3) as stripping solution, Span-80 as surfactant was studied. The stability of the prepared ELM was studied in terms of the degree of membrane breakage. The different parameters affecting the permeation of gadolinium (III) were also studied. A general permeation model for the recovery of Gd(III) by the selected membrane is presented. The internal mass transfer in the water in oil (W/O) emulsion drop, the external mass transfer around the drop, the rates of formation and decomposition of the complex at the external aqueous-organic interface were considered.
Equilibrium and Kinetic Studies on the Separation of Uranium and Thorium from Nitric Acid Medium by Liquid Emulsion Membrane Based on Trioctylphosphine Oxide Extractant
It was found that the extraction percent (E%) values of U(VI), Th, Zr and Fe(III) from 0.1mol dm-3 (M) HNO3 solution by 0.1M TOPO in cyclohexane solution are 98, 78, 85 and 85%, respectively. Among these elements, only U(VI) and Th were found to be stripped from their organic phase by 0.1M sodium citrate solution. Cerium, copper and cadmium were not extracted by trioctylphosphine oxide (TOPO) under similar conditions. Based on these equilibrium results, a liquid emulsion membrane (LEM) was prepared from TOPO/Span 80/sodium citrate and the factors affecting its stability were studied. Permeation of U(VI) into this membrane was kinetically studied in detail. Its forward permeation rate was found to be mainly dependent on TOPO concentration and slightly dependent on U(VI) and HNO3 concentration of the external phase. Permeation results showed that it is possible to recover 98% of U(VI) and 82% of Th from 0.1M HNO3 solution containing Ce, Zr, Fe(III), Cd, and Cu by the membrane. The recovered U(VI) and Th were contaminated with less than 2% of Fe(III).
Enhancement of surface properties on Low Density Polyethylene packaging films using various fluorination routes
Nowadays, packaging market deployment requires an important attention. Influence of treatment with molecular (F2) or atomic (Fradical dot) fluorine on properties of Low Density Polyethylene (LDPE) films was investigated. The films were treated using direct fluorination conditions with F2 or a specific reagent XeF2, which releases atomic fluorine Fradical dot. Changes of LDPE chemical composition were investigated by FTIR and solid state NMR. Surface morphology was studied by several microscopy techniques (SEM and AFM). Finally to further characterize film properties after treatments, surface energy measurements and electron paramagnetic resonance (EPR) analyses were also carried out. An upper fluorinated layer, which contains mainly high amount of single bondCF2single bond, was formed during the direct fluorination conditions (F2). For the process performed with XeF2, specific groups single bondCHFsingle bond were detected not only on the polymer surface but also in the bulk. The final CHF/CF2 ratio depended on the fluorination route. Treatment with Fradical dot (originated from XeF2 decomposition) resulted in single bondCHFsingle bond groups in bulk prevailing formation whereas F2 formed mainly single bondCF2single bond groups. Regardless to the reactive species, radicals (dangling bonds) appeared during the fluorination and reacted with oxygen during the exposition to air after the treatment. Such a process resulted in oxygenated polar groups formation and consequently in the surface energy increase.