Characterization of Polymer Inclusion Membranes (PIMs) Containing Phosphonium Ionic Liquids as Zn(II) Carriers

Research on Membranes and Their Associated Processes at the Université Paris-Est Créteil: Progress Report, Perspectives, and National and International Collaborations

Research on membranes and their associated processes was initiated in 1970 at the University of Paris XII/IUT de Créteil, which became in 2010 the University Paris-Est Créteil (UPEC). This research initially focused on the development and applications of pervaporation membranes, then concerned the metrology of ion-exchange membranes, then expanded to dialysis processes using these membranes, and recently opened to composite membranes and their applications in production or purification processes. Both experimental and fundamental aspects have been developed in parallel. This evolution has been reinforced by an opening to the French and European industries, and to the international scene, especially to the Krasnodar Membrane Institute (Kuban State University-Russia) and to the Department of Chemistry, (Qassim University-Saudi Arabia). Here, we first presented the history of this research activity, then developed the main research axes carried out at UPEC over the 2012-2022 period; then, we gave the main results obtained, and finally, showed the cross contribution of the developed collaborations. We avoided a chronological presentation of these activities and grouped them by theme: composite membranes and ion-exchange membranes. For composite membranes, we have detailed three applications: highly selective lithium-ion extraction, bleach production, and water and industrial effluent treatments. For ion-exchange membranes, we focused on their characterization methods, their use in Neutralization Dialysis for brackish water demineralization, and their fouling and antifouling processes. It appears that the research activities on membranes within UPEC are very dynamic and fruitful, and benefit from scientific exchanges with our Russian partners, which contributed to the development of strong membrane activity on water treatment within Qassim University. Finally, four main perspectives of this research activity were given: the design of autonomous and energy self-sufficient processes, refinement of characterization by Electrochemical Scanning Microscopy, functional membrane separators, and green membrane preparation and use.

Vanadium recovery by electrodialysis using polymer inclusion membranes

Industrial applications and environmental awareness recently prompted vanadium recovery spell from secondary resources. In this work, a polymer inclusion membrane containing trioctylmethylammonium chloride as carrier was successfully employed in electrodialysis for vanadium recovery from acidic sulfate solutions. The permeability coefficient of V(V) increased from 0.29 µm·s^-1 (without electric field) to 4.10 µm·s^-1 (with the 20 mA·cm^-2 current density)_. The transport performance of VO₂SO₄^-, which was the predominant species containing V(V) in the acidic region (pH <3), was influenced by the aqueous pH value and sulfate concentration. Under an electric field, a low concentrated H₂SO₄ solution (0.2 M) effectively stripped V(V) from the membranes, avoiding the requirement of a highly concentrated H₂SO₄ without electric field. Under the optimum conditions, the permeability coefficient and flux reached 6.80 µm·s^-1 and 13.34 µmol·m^-2·s^-1, respectively. High selectivity was observed for the separation of V(V) and Mo(VI) from mixed solutions of Co (II), Ni (II), Mn (II), and Al (III). Additionally, the separation between Mo(VI) and V(V) was further improved by adjusting the acidity of the stripping solution. The V(V) selectivity for the resulting membrane was higher than that of commercial anion exchange membranes.

Rare Earth Elements Recovery Using Selective Membranes via Extraction and Rejection

Recently, demands for raw materials like rare earth elements (REEs) have increased considerably due to their high potential applications in modern industry. Additionally, REEs' similar chemical and physical properties caused their separation to be difficult. Numerous strategies for REEs separation such as precipitation, adsorption and solvent extraction have been applied. However, these strategies have various disadvantages such as low selectivity and purity of desired elements, high cost, vast consumption of chemicals and creation of many pollutions due to remaining large amounts of acidic and alkaline wastes. Membrane separation technology (MST), as an environmentally friendly approach, has recently attracted much attention for the extraction of REEs. The separation of REEs by membranes usually occurs through three mechanisms: (1) complexation of REE ions with extractant that is embedded in the membrane matrix, (2) adsorption of REE ions on the surface created-active sites on the membrane and (3) the rejection of REE ions or REEs complex with organic materials from the membrane. In this review, we investigated the effect of these mechanisms on the selectivity and efficiency of the membrane separation process. Finally, potential directions for future studies were recommended at the end of the review.

Removal of Copper (II), Zinc (II), Cobalt (II), and Nickel (II) Ions by PIMs Doped 2-Alkylimidazoles

Polymer inclusion membranes (PIMs) are an attractive approach to the separation of metals from an aqueous solution. This study is concerned with the use of 2-alkylimidazoles (alkyl = methyl, ethyl, propyl, butyl) as ion carriers in PIMs. It investigates the separation of copper (II), zinc (II), cobalt (II), and nickel (II) from aqueous solutions with the use of polymer inclusion membranes. PIMs are formed by casting a solution containing a carrier (extractant), a plasticizer (o-NPPE), and a base polymer such as cellulose triacetate (CTA) to form a thin, flexible, and stable film. The topics discussed include transport parameters, such as the type of carrier, initial fluxes, separation coefficients of copper in relation to other metals, as well as transport recovery of metal ions. The membrane was characterized using AFM and SEM to obtain information on its composition.

Transport of Rhodium(III) from Chloride Media across a Polymer Inclusion Membrane Containing an Ionic Liquid Metal Ion Carrier

Efficient and selective transport of rhodium(III) across a polymer inclusion membrane (PIM) from a 0.1 mol dm^-3 HCl feed solution, also containing iron(III), to a receiving solution containing 0.1 mol dm^-3 HCl and 4.9 mol dm^-3 NH₄Cl was achieved using a phosphonium-type ionic liquid, trioctyl(dodecyl)phosphonium chloride (P₈₈₈₁₂Cl), as the metal ion carrier. The optimum PIM composition for the Rh(III) transport was 50 wt % poly(vinylidene-co-hexafluoropropylene) (PVDF-HFP), 30 wt % P₈₈₈₁₂Cl, and 20 wt % plasticizer 2-nitrophenyl octyl ether (2NPOE). The driving force for the Rh(III) transport was suggested to be the concentration difference of the chloride ion between the feed and the receiving solutions. More than 70% rhodium(III) could be recovered from the receiving solution, and no transport of iron(III) was observed; however, the two metal ions cannot be separated by liquid-liquid extraction. This is the first report of selective transport of rhodium(III) across a polymer inclusion membrane.

Selective Separation of Acetic and Hexanoic Acids across Polymer Inclusion Membrane with Ionic Liquids as Carrier

This paper first reports on the selective separation of volatile fatty acids (VFAs) (acetic and hexanoic acids) using polymer inclusion membranes (PIMs) containing quaternary ammonium and phosphonium ionic liquids (ILs) as the carrier. The affecting parameters such as IL content, VFA concentration, and the initial pH of the feed solution as well as the type and concentration of the stripping solution were investigated. PIMs performed a much higher selective separation performance toward hexanoic acid. The optimal PIM composed of 60 wt% quaternary ammonium IL with the permeability coefficients for acetic and hexanoic acid of 0.72 and 4.38 µm s⁻¹, respectively, was determined. The purity of hexanoic acid obtained in the stripping solution increased with an increase in the VFA concentration of the feed solution and decreasing HCl concentration of the stripping solution. The use of Na₂CO₃ as the stripping solution and the involvement of the electrodialysis process could dramatically enhance the transport efficiency of both VFAs, but the separation efficiency decreased sharply. Furthermore, a coordinating mechanism containing hydrogen bonding and ion exchange for VFA transport was demonstrated. The highest purity of hexanoic acid (89.3%) in the stripping solution demonstrated that this PIM technology has good prospects for the separation and recovery of VFAs from aqueous solutions.

Selective removal of silver(i) using polymer inclusion membranes containing calixpyrroles

The transport of Ag(i) across polymer inclusion membranes is reported with derivatives of calixpyrroles with methyl (KP1) and carboxyl (KP2) groups as ion carriers, o-nitrophenyl pentyl ether as a plasticizer and cellulose triacetate as support.