Mourad Amara

Modification of the cation exchange resin properties by impregnation in polyethyleneimine solutions: application to the separation of metallic ions.

A commercial cation exchange resin Amberlite 200 has been modified after immersion in solutions of polyethyleneimine (PEI). The kinetic of fixation of the metallic ions have been determined. The modification of the surface of the resin deals with a change in the order of the affinities of the resins towards cations. The retention is the function of the formation and the stability of the complex. The conditions of modification (pH, PEI concentration and time of immersion) have been examined and the modification was confirmed by the determination of the exchange capacities, the distribution coefficient (P) and the selectivity factors (S). The obtained results revealed the effect of PEI on the exchange properties of the resin. The pH range selected (6-8) permitted a good adherence of PEI onto the resin surface. The quantity of the adsorbed PEI was increased by raising the initial concentration and the immersion period. The exchange capacity for copper ion passed from 2.6 mmol g(-1), in the case of unmodified resin, to 3.9 mmol g(-1) for the modified one.

Modification of cation-exchange membrane properties by electro-adsorption of polyethyleneimine

Abstract A cation-exchange membrane has been modified by fixation of polyethyleneimine on its surface. This fixation was carried out under an electric field effect, thus it is called electro-adsorption. The polycation formed in an acidic medium migrated toward the membrane and a charged layer was deposited on the surface, and the selectivity towards divalent ions decreased, yielding to the increase of the proton transfer. When the amount of adsorbed PEI increased, the electrical resistance ofthe membrane increased and the transport number of zinc decreased. However, suitable conditions like pH, current density and electro-adsorption time were controlled in the order to obtain membranes with better selectivity and low electrical resistance.

Modified membranes applied to metallic ion separation and mineral acid concentration by electrodialysis

Abstract Two modified membranes are used for the treatment of industrial effluent by electrodialysis. This surface modification of membrane using both immersion and electrodeposition method improves the selectivity for monovalent ions against to divalent. In this work both neutralisation of the effluent and acid enrichment are achieved. The immersion method appears more efficient when not morethan two compounds are inside the solution. On the other hand, electrodeposition technique should be used allowing to attain 2.8 N acid concentration. It was noticed that polyethyleneimine plays two different roles according to the modification method. The multilayer was formed by adsorption using immersion method though electrodeposition technique permits PEI to penetrate into the pores and play a role of an effective carrier for proton.

Modified cation exchange resin applied to demineralisation of a liquid industrial waste. Comparison to a classical treatment and electrodialysis

Abstract An experimental study has been made on the separation and recovery of some metals from an effluent waste. Three methods (i.e. classical neutralisation, electrodialysis and ion exchange) were used and compared. Purification efficiency was determined in all cases of treatment. It was found that classical treatment causes formation of a large amount of sludge constituted principally of Al(OH) 3 , Fe(OH) 3 and CaSO 4 . Ten grams of solid were formed using 1 L of effluent treated. The electrodialysis process was efficient for removal of monovalent anions such as Cl − and NO 3 − from effluent using a monovalent selective anion exchange membrane. Increase of current density causes an increase of efficiency. Finally, a cation exchange resin modified by adsorption of tetrabutylammonium or polyethyleneimine on its surface was used and compared to unmodified resin and the two methods of treatment cited above. Modification of the resin surface allowed separation of species according to their valencies and hydration. Cations with high valencies were fixed on the resin modified by tetrabutylammonium, while transition metals were retained by chelate bonding with polyethyleneimine fixed on resin modified by this polyelectrolyte.

Cadmium (II) and lead (II) transport in a polymer inclusion membrane using tributyl phosphate as mobile carrier and CuFeO2 as a polarized photo electrode

In this work, a development of polymeric inclusion membranes for the cations separation is reported. The membrane was made up of cellulose triacetate (CTA) with a tributyl phosphate (TBP) incorporated into the polymer as metal ions carrier. The transport of lead (II) and cadmium (II) ions in two membrane systems polymer inclusion membrane (PIM), PIM coupled with photo-chemical electrode using TBP as carrier and 2-nitro phenyl octyl ether (NPOE) or tris ethylhexyl phosphate (TEHP) as plasticizer have been investigated. The membranes: polymer+plasticizer+carrier were synthesized and characterized by FTIR, X-ray diffraction and scanning electron microscopy (SEM). Transports of lead and cadmium have been studied using these systems and the results were compared to commercial cation exchange membrane (CRA). The obtained results showed that for Pb(2+) ion, the concentrations of the strip phase increases using synthesized membranes. The conduction band of the delafossite CuFeO(2) (-1.25 V(SCE)) yields a thermodynamically M(2+) (=Pb(2+), Cd(2+)) photo electrodeposition and speeds up the diffusion process. In all the cases, the potential of the electrode M/M(2+) in the feed compartment increases until a maximum value, reached at approximately 100 min above which it undergoes a diminution.

Synthesis of modified polymer inclusion membranes for photo-electrodeposition of cadmium using polarized electrodes

In this work, we have developed a novel class of polymeric inclusion membranes (PIMs) for the cations separation. The membrane is made up of cellulose triacetate modified by poly-electrolytes (poly-phosphoric acid, polyvinyl pyrolidone, polyacrylic acid, polyvinyl alcohol and poly-anetholsulfonic acid) using 2-hydroxy-5-dodecylbenzaldehyde incorporated into the polymer as carrier and tris ethyl hexyl phosphate or glycerine as plasticizers. Different PIMs are synthesized and characterized by the Fourier transform infrared, X-ray diffraction, thermal analysis and scanning electron microscopy. The influence of the membrane nature is studied using supports with different physical characteristics (porosity, thickness, hydrophobia). As application, the transport of Cd(2+) using PIMs coupled with photo-electrodes is investigated. The photo-catalytic results indicate that the combined system p-CuFeO(2)/membrane/n-WO(3) enhances considerably the electrons transfer toward the delafossite CuFeO(2). The position of the conduction band of CuFeO(2) is looked to be the key issue for the photo electrochemical Cd(2+) reduction.

An assembled poly-4-vinyl pyridine and cellulose triacetate membrane and Bi2S3 electrode for photoelectrochemical diffusion of metallic ions

The transport phenomena across ion exchange membrane may be enhanced by applying various strengths inside or outside the system. The electrical current, generated by n-type semiconductor, is used to catalyse the separation of metal ions. The cation exchange membrane located between the two compartments allows both the separation and concentration of M(n+) (Ag(+), Cu(2+), Pb(2+) and Ni(2+)). The flows of M(n+) from the aqueous solution to-and inside the membrane are monitored by the determination of the fluxes and the potentials. In this study, the four cations are investigated alone or in quaternary systems. From photoelectrochemical measurement, the gap of Bi(2)S(3) is found to be indirect at 1.65 eV. The shape of photocurrent potential curve and the negative flat band potential (-1.02 V(SCE)) give evidence of n-type character. The conduction band (-1.25 V(SCE)) yields thermodynamically M(2+) photoreduction and catalyzes the diffusion process. The photoelectrode Bi(2)S(3) makes the flux twofold greater than that observed in the dark. In all cases, the potential of the electrode M(2+)/M in the feed compartment increases until a maximal value, reached at approximately 100 min above which it undergoes a diminution. The membrane is more selective to Cu(2+) and this selectivity decreases in the quaternary system.

Transfer of nitrate ions using a polymeric-surfactant membrane

AbstractThe polymer surfactant membranes used for the selective transport and separation of different species has emerged in recent years. In this work, a development of a novel class of surfactant membrane for performing nitrates ions elimination is reported. The influence of the composition of stripping solution on the separation of nitrate ions by Donnan dialysis using a polymeric membrane was studied. The membrane was prepared by dissolving a calculated amount of cellulose triacetate and poly-vinylpyrrolidone in chloroform after additive of polysorbate as surfactant. The obtained film after evaporation of the solvent is characterized by Fourier trans form infrared spectroscopy and thermo-gravimetric analysis. The degradation of the membranes occurs via two steps process whose main loss starts at 200°C is due to the thermal degradation of the polymeric chains. As application, cross ionic dialysis process was used, thus hydrogen ion from HCl medium give to the nitrate transference rather than Na+ ion fr...

The effect of thiourea as a complexing agent on the separation of metallic ions through cation exchange membranes by Donnan dialysis

Donnan dialysis has been investigated in this work in the order to exhibit the influence of the composition of solution on the performance of commercial cation exchange membrane toward metallic ions. Transference fluxes have been determined either as experimental values or calculated according to theoretical models. A good agreement between theoretical and experimental flows has been obtained principally in the case of CMV membrane which presents a lower thickness. It has been demonstrated that addition of thiourea causes an increase of separation properties of membrane. The separation is mainly due to the complex formation between Ag+ and Cu+ ions and thiourea. Monovalent copper ion is obtained after reduction of Cu2+ and oxidation of thiourea and formation of bisulfide of formamidine which constitute a barrier to monovalent complex transference.

Study of various parameters influencing the fixation of metallic ions Cu2+, Zn2+, and Ni2+ at the catalytic Amberlyst-15 resin in the presence of alcohols

The ionic exchange behavior of Zn2+, Ni2+, and Cu2+ metallic ions on Amberlyst-15 commercial resin was studied as a function of resin solution contact time, initial concentration of metallic ions, nature of the solvent, and the amount of resin. The metallic ions were studied in ternary mixtures using both column and batch experiments. In addition, water, methanol, ethanol, and propan-2-ol were used as solvents for dissolving metallic ions. It was found that the resin behavior depends on the solvent nature and the metallic ion concentration. The analysis of solutions by atomic absorption spectrometry revealed that the affinity of the resin for the studied metallic ions followed the sequence Cu2+ > Ni2+ > Zn2+ in the case of an aqueous medium. Furthermore, uptake increased with increasing amount of resin. A better uptake was observed in the case of the 75:25 % water/methanol compositions when the column technique was used. For the batch technique, we noted a better uptake using 100 % water. The uptake rate decreased with an increase in the number of carbons for the 50 % water–50 % alcohol solvents. The acid–base properties of Amberlyst-15 commercial resin were studied by 2-propanol decomposition test. Propene and acetone are the main expected products and it is believed that they are formed through dehydration or dehydrogenation reaction on acid and base sites, respectively.