Omar Arous

Removal of Ag(l), Cu(II) and Zn(ll) ions with a supported liquid membrane containing cryptands as carriers

Abstract The interface behaviour in the facilitated co-transport of Ag(I), Cu(II) and Zn(II) ions through supported liquid membranes (SLMs) made of a flat-sheet polypropylene membrane support containing cryptands (2.2.2 or 2.2.1) as carriers was studied. The liquid-liquid extraction tests showed a maximum distribution coefficient when the carrier concentration was greaterthan 10−4M. In transport experiments the transmembrane flux increased with increasing carrier concentration reaching a limiting value at greater than 10−3M concentration. The calculation ofthe diffusion coefficients in membranes showed ahigherdiffusivityof2.2.2-metal complexes with respect to 2.2.1-metal complexes for silver ions. A sequence of diffusivity D(Ag+)>D(Cu2+)>D(Zn2+) was obtained, but carrier 2.2.1 showed a higher selectivity through copper ions. A sequence of diffusivity D(Cu2+)>D(Zn2+)>D(Ag+) was obtained. The diffusivity was significantly higher when using Celgard 2500 support compared to Celgard 2400 or 2402. Variable metal ion concentrations in the feed phase fluxes almost zero, at less than 10−2 M concentration, were obtained. In the transient state of the transport through the SLM, different molar flow rates at the feed-membrane and membrane-strip interfaces were observed. The selectivity of the interfaces containing 2.2.2 in the separation binary mixtures of ions showed the following separation factors: SFAgZn = 2.50, SFAgCu = 1.64, SFcuZn = 1.42.

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.

Utilization of Mono and Bicyclic Polyethers as Mobile Carriers of Silver, Copper, and Zinc Through a Supported Liquid Membrane

Abstract The behavior of a monocyclic polyether (crown ether) and a bicyclic polyether (cryptand) towards liquid–liquid extraction and facilitated cotransport of silver, copper, and zinc was investigated. It was shown that, with regard to their structure, the relative size of their macrocycle cavities, and the nature of the inserted ion, considerably influences the efficiency of the extraction and the cotransport. On the other hand, this study also revealed the formation of emulsions in the monocyclic polyether organic phase that constitute a barrier for the carrier–metal complex formation in the membrane support. An impregnation time of 1 hr of the support in the organic phase is necessary to achieve good efficiency for the supported liquid membrane (SLM). The optimum of the other fundamental parameters (polyether concentration, metal concentration, and support characteristics) were determined.

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.

Membranes based on polymer miscibility for selective transport and separation of metallic ions

Polymer inclusion membranes (PIM) used for selective transport and separation of metallic ions have emerged in recent times. Their expansion depends on the method of preparation and their suitable structure and physico-chemical characteristics. In this paper, a novel category of membranes for ions separation is reported. The membranes were synthesized by thermally induced phase separation using a mixture of polyvinylidene fluoride (PVDF) and cellulose triacetate (CTA) plasticized by tris(2-ethylhexyl) phosphate (TEHP) and with di-(2-ethylhexyl) phosphoric acid (D2EHPA) incorporated into the polymer as carrier to increase specific interactions between polymers. PIM membrane exhibited a hydrophobic (∼100°) and thermally stable up to ∼200°C porous homogenous structure. The transport of Ni(II), Zn(II) and Pb(II) from aqueous solutions was studied by competitive transport across polymer inclusion membranes (PIM). Competitive transport of ions in solution across PIM provide the selectivity order: Ni2+ (45%)>Pb2+ (35%)>Zn2+ (5%). A long-term transport experiment was carried out to study the durability of the system.

Cellulose triacetate properties and their effect on the thin films morphology and performance

Development of a novel class of thin film for performing cations separation is reported. The thin film is polymerized from cellulose triacetate (CTA) with a tributyl phosphate (TBP) as carrier. Transport of lead and cadmium ions in two different membrane systems (Polymer Inclusion Membrane (PIM) and Supported Liquid Membrane (SLM) using TBP as carrier and 2nitro phenyl octyl ether (NPOE) or Trisethylhexylphosphate (TEHP) as plasticizer has been investigated. The membranes CTA-NPOE-Carrier and CTA-TEHP-Carrier were synthesised and characterised using chemical techniques as well as FTIR spectroscopy and scanning electron microscopy (SEM). CTA membrane is characterised by well-defined pores, these pores which are completely filled with plasticizer and carrier. Surfaces of membranes with TBP are smooth. The systems constituted by the mixture of CTA-NPOE and CTA-NPOE-TBP do not give any diffraction peak. The influence of the membrane nature has been studied using three supports of different physical characteristics. The obtained results showed that for Pb2+ ion, the concentrations of strip phase increases using synthesized membranes.

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...

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.

Surfactant-based modification of sodic-Algerian illite clay for the preparation of polymeric membranes: application for separation of iron and zinc ions from aqueous solutions

AbstractIn the present work, polymer solutions of cellulose triacetate (CTA) and tris-ethylhexyl phosphate (TEHP) mixed with Algerian green illite clay were used to prepare selective filtration membranes by the phase inversion technique via immersion precipitation. The effect of a local clay additive on the structure and performances of the membranes was studied. Algerian clay was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), x-ray fluorescence (XRF) and scanning electron microscopy (SEM). The obtained hybrid membranes were characterized by XRD, Fourier transform infrared spectroscopy (FTIR-ATR), TGA and contact angle measurements. All the synthesized membranes had an amorphous structure without any diffraction peak. This could be due to the absence of crystallization within the membrane. As the plasticizer molecules were hydrophobic, their location at the surface of the modified polymeric membranes is expected to modify the contact angle. Overall, our results show that the addition of plasticizer to the hybrid material (polymer and clay) results in homogeneous and hydrophobic membranes of which the physical properties were ameliorated compared to (CTA + Clay) membranes. As applications, transport of Zn(II) and Fe(III) in polymeric membranes using (CTA + TEHP + Clay) membranes was studied.