Selective Separation Of Metal Ions Research Articles

Polymeric Inclusion Membranes Based on Ionic Liquids for Selective Separation of Metal Ions.

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim+][PF6-] and methyl trioctyl ammonium chloride, [MTOA+][Cl-]. For this purpose, stability studies of different IL/base polymer compositions against aqueous phases were carried out. Among all polymer inclusion membranes studied, [omim+][PF6-]/PVC membranes at a ratio of 30/70 and [MTOA+][Cl-]/PVC membranes at a ratio of 70/30 were able to retain up to 82% and 48% of the weight of the initial ionic liquid, respectively, after being exposed to a solution of metal ions in 1 M HCl for 2048 h (85 days). It was found that polymer inclusion membranes based on the ionic liquid methyl trioctyl ammonium chloride allowed the selective separation of Zn(II)/Cu(II) and Zn(II)/Fe(III) mixtures with separation factors of 1996, 606 and, to a lesser extent but also satisfactorily, Cd(II)/Cu(II) mixtures, with a separation factor of 112. Therefore, selecting the appropriate ionic liquid/base polymer mixture makes it possible to create polymeric inclusion membranes capable of selectively separating target metal ions.

Studies on Selective Separation of Metal Ions with Ion Exchange Materials by Immobilizing Extractant

Studies on Selective Separation of Metal Ions with Ion Exchange Materials by Immobilizing Extractant

Separation of valuable metals in spent LiNi0.46Co0.2Mn0.34O2 battery by shear induced dissociation coupling with ultrafiltration

There are valuable metals in spent ternary lithium-ion batteries. A method for selective separation of Al (III), Fe (III), Li (I), Mn (II), Co (II), Ni (II) and Cu (II) from acid leaching of spent LiNi0.46Co0.2Mn0.34O2 battery was proposed. Al (III) and Fe (III) are firstly separated by chemical precipitation, and other metal ions are formed polymer-metal complexes by adding polyacrylate sodium (PAAS) as complexing agent. According to the difference of shear stabilities of PAA-metal complexes, selective separation of metal ions was fulfilled by shear induced dissociation coupling with ultrafiltration using rotating disk membrane (RDM). The shear induced dissociation mechanism of polymer-metal complex was studied. Compared with the traditional separation methods, such as acidification and extraction, shear induced dissociation coupling with ultrafiltration without the consumption of acid and alkali, is green and environmentally friendly effective method for the recovery of metal ions.

Wavelength selective separation of metal ions using electroactive ligands.

The separation of metal ions can be challenging because of similarities in charge density, size, and binding affinities. Here, we introduce a new photochemical separation strategy that relies on the intrinsically unique photophysical properties of metal ion complexes and the selective transformation of an electroactive ligand.

Pectin–Tin(IV) molybdosilicate: An ecofriendly cationic exchanger and its potential for sorption of heavy metals from aqueous solutions

A novel composite cation exchanger of biopolymer Pectin and Tin(IV) molybdosilicate heteropoly acid salt were prepared by co-precipitationtechnique. Physico-chemical characterization of Pectin–Tin(IV) molybdosilicate was performed using instrumental techniques such as FTIR,TG, XRD and SEM–EDS. Studies were carried out to investigate ion exchange capacity. pH titration carried out shows cationic nature andpolyfunctionality of the exchanger. Distribution coefficients of various metal ions were done to explore the ion exchange behavior of cationexchanger. Distribution studies show that the material is highly selective for toxic heavy metal ions such as Cd2+, Cu2+, Al3+ etc. To investigate theenvironmental applicability of the exchanger some analytically important binary separations and selective separation of metal ions from industrialeffluents were achieved. Kinetic and isotherm parameters were evaluated to predict the mechanism of sorption of heavy metal ions. Mass transferanalysis shows that internal particle diffusion and some degree of boundary layer control the sorption process.

Pectin–Tin(IV) molybdosilicate: An ecofriendly cationic exchanger and its potential for sorption of heavy metals from aqueous solutions

A novel composite cation exchanger of biopolymer Pectin and Tin(IV) molybdosilicate heteropoly acid salt were prepared by co-precipitation technique. Physico-chemical characterization of Pectin–Tin(IV) molybdosilicate was performed using instrumental techniques such as FTIR, TG, XRD and SEM–EDS. Studies were carried out to investigate ion exchange capacity. pH titration carried out shows cationic nature and polyfunctionality of the exchanger. Distribution coefficients of various metal ions were done to explore the ion exchange behavior of cation exchanger. Distribution studies show that the material is highly selective for toxic heavy metal ions such as Cd2+, Cu2+, Al3+ etc. To investigate the environmental applicability of the exchanger some analytically important binary separations and selective separation of metal ions from industrial effluents were achieved. Kinetic and isotherm parameters were evaluated to predict the mechanism of sorption of heavy metal ions. Mass transfer analysis shows that internal particle diffusion and some degree of boundary layer control the sorption process.

Selective Separation of Metal Ions via Monolayer Nanoporous Graphene with Carboxyl Groups.

Graphene-coated plastic substrates, such as polyethylene terephthalate (PET), are regularly used in flexible electronic devices. Here we demonstrate a new application of the graphene-coated nanoporous PET membrane for the selective separation of metal ions in an ion exchange manner. Irradiation with swift heavy ions is used to perforate graphene and PET substrate. This process could create graphene nanopores with carboxyl groups, thus forming conical holes in the PET after chemical etching to support graphene nanopores. Therefore, a monolayer nanoporous graphene membrane with a PET substrate is constructed successfully to investigate its ionic selective separation. We find that the permeation ratio of ions strongly depends on the temperature and H+ concentration in the driving solution. An electric field can increase the permeation ratio of ions through the graphene nanopores, but it inhibits the ion selective separation. Moreover, the structure of the graphene nanopore with carboxyl groups is resolved at the density functional theory level. The results show the asymmetric structure of the nanopore with carboxyl groups, and the analysis indicates that the ionic permeation can be attributed to the ion exchange between metal ions and protons on the two sides of graphene nanopores. These results would be beneficial to the design of membrane separation materials made from graphene with efficient online and offline bulk separation.

Polysulfone‐based composite membranes with functionalized carbon nanotubes show controlled porosity and enhanced electrical conductivity

ABSTRACTComposite membranes of functionalized (–COOH, –CONH2, –N3) carbon nanotubes/polysulfone (CNT/PS) synthesized by the phase‐inversion method show unique properties with respect to surface characteristics and the selective separation of metal ions from aqueous solution. Apart from the reduction in the pore size depending on the type of functionalities on the nanotubes, the pure water permeation could reach up to as high as ∼600 L m−2 h−1 (LMH) at reduced pressures and could be due to the functionalized tips of the nanotubes on the membrane surface resulting from the phase inversion process used for the membrane fabrication. The membranes were characterized by small angle neutron scattering (SANS) to confirm the uniform distribution of the nanopores and the surface morphology of the membranes. Results show that rejection of Cu(II) was better than Pb(II) depending on the surface functionality. Interestingly, these membranes also showed enhanced conductivities in the range of 1.0 × 10−2 S cm−1, the conductivity depending on the type of functionality on the nanotubes, thus confirming the presence of functionalized nanotubes tips on the membrane surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43778.

On the selective separation of metal ions from hydrochloride aqueous solution by pertraction through supported ionic liquid membranes

Previously, we reported the use of imidazolium and ammonium based ionic liquids in the absence of chelating agents for the selective liquid–liquid extraction of Zn(II), Cd(II), Cu(II), and Fe(III) from hydrochloride aqueous solutions. It was found that the ionic liquid methyltrioctylammonium chloride, [MTOA+][Cl−], allowed the almost complete removal of Zn(II), Cd(II), Fe(III) and Cu(II) from the aqueous solutions. In this work, supported ionic liquid membranes based on methyltrioctylammonium chloride were used in an pertraction process for the selective extraction of Fe(III), Zn(II), Cd(II) and Cu(II). The influence of the composition of the receiving phase (milliQ water or Na2CO3, 0.1M; or NH3,6M) in the pertraction process was analyzed. It was found that Milli-Q water and Na2CO3 allowed the recovery of Zn(II), Fe(III), reaching pertraction factors (PFs), defined as the ratio between the concentration of the target metal ion in the receiving and the feed phase, of up to 373 for Zn(II), using Na2CO3 as receiving phase at 48h and 9 for Fe(III), using Milli-Q water at 31h. The use of NH3 (6M) allowed the recovery of Cd(II), with a PF of 15.1 at 24h. Therefore, by modifying the stripping composition, the selective separation of the target metal ions can be reached. It is worthy to highlight the remarkable stability of the obtained supported ionic liquid membranes.

Liquid membrane operations in a microfluidic device for selective separation of metal ions.

A three-phase flow, water/n-heptane/water, was constructed in a microchannel (100-microm width, 25-microm depth) on a glass microchip (3 cm x 7 cm) and was used as a liquid membrane for separation of metal ions. Surface modification of the microchannel by octadecylsilane groups induced spontaneous phase separation of the three-phase flow in the microfluidic device, which allows control of interfacial contact time and off-chip analysis using conventional analytical apparatus. Prior to the selective transport of a metal ion through the liquid membrane in the microchannel, the forward and backward extraction of yttrium and zinc ions was investigated in a two-phase flow on a microfluidic device using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (commercial name, PC-88A) as an extractant. The extraction conditions (contact time of the two phases, pH, extractant concentration) in the microfluidic device were examined. These investigations demonstrated that the conventional methodology for solvent extraction of metal ions is applicable to solvent extraction in a microchannel. Finally, we employed the three-phase flow in the microchannel as a liquid membrane and observed the selective transport of Y ion through the liquid membrane. In the present study, we succeeded, for the first time, in the selective separation of a targeted metal ion from an aqueous feed solution to a receiving phase within a few seconds by employing a liquid membrane formed in a microfluidic device.

Poly[acrylamide-co-1-(2-hydroxyethyl)aziridine]: An efficient water-soluble polymer for selective separation of metal ions

Poly[acrylamide-co-1-(2-hydroxyethyl)aziridine], obtained by spontaneous copolymerization, which contains different types of ligand groups as tertiary amines and hydroxyl and amide groups, was tested as a polychelatogen using the liquid-phase polymer-based retention (LPR) technique. The metal ion retention ability of this polymer was found to depend on the pH and it showed a high selectivity to copper(II) at pH 5. The maximum capacity of Cu(II) was determined at pH 5 by using the enrichment variant of LPR. The retention capacities of the polymer with Cu(II), Cd(II), Co(II), Cr(III), Ni(II), Pb(II), Zn(II), and Fe(II) were studied at different pH and the results are compared with those of branched polyethylenimine and poly[1-(2-hydroxyethyl)aziridine] homopolymers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 817–824, 1998

Polymer-Metal Complexes of N,N′-Methylene-bis-acrylamide(NNMBA)-Crosslinked Polyacrylamide-Supported Glycines: Effect of the Degree of Crosslinking On Metal ion Complexatlon and Concentration

ABSTRACT Glycine functions were incorporated into 2–20 mol% N,N′-methylene-bis-acrylamide (NNMBA)-crosslinked polyacrylamides by transamidation with excess sodium salt of glycine. Complexation characteristics of glycine functions in different structural environments were investigated towards Co(II), Ni(II), Cu(II) and Zn(II) ions. The observed trend in complexation was found to be: Cu(II) > Ni(II) > Co(II) > Zn(II). The polymeric ligands and metal complexes were characterized by various spectral techniques. The polymeric ligands could be recycled several times and the metal ion desorbed resins showed specificity to the desorbed metal ion than other metal ions. This originates from the development of certain ‘pockets’ left by the desorbed metal ion or the ‘memory’ of the polymeric ligands for the desorbed metal ion. This lightly crosslinked systems showed much faster rebinding kinetics. The conditions of metal ion binding and rebinding were optimized to exploit the specific and selective separation of metal ions using metal ion desorbed systems. The specificity and selectivity characteristics depend on the degree of NNMBA crosslinking.

Templated Polymers for Recognition and Selective Separation of Metal Ions

Templated Polymers for Recognition and Selective Separation of Metal Ions

Dialkyldithiophosphate substituted on poly(vinylchloride): Synthesis and performance

AbstractPreparation of sodium salt of di(2‐ethylhexyl)dithiophosphoric acid (DTPANa) by reaction of the corresponding DTPA with sodium hydride has been described. Nucleophilic substitution of chlorine on poly(vinylchloride) (PVC) by a di(2‐ethylhexyl)dithiophosphate group resulting in modified polymer (MP) was characterized by the second order rate constant equal to 6.6 × 10−5 M−1 s−1. Formation of homogeneous stable gelled phases composed of MP and DTPA, as well as MP, PVC, and DTPA, was demonstrated. The gelled material is capable of selective separation of metal ions under the conditions of extraction chromatography. © 1993 John Wiley & Sons, Inc.

Gelled membrane composed of dioctyldithiocarbamate substituted on poly(vinylchloride) and di (2‐ethylhexyl) dithiophosphoric acid

AbstractSubstitution of chlorine of poly(vinylchloride) (PVC) by dioctyldithiocarbamate (DODTC) groups results in a modified polymer (MP) with a glass transition temperature of between −43 and 84°C, depending on the degree of substitution. Formation of a gelled membrane composed of MP and di (2‐ethylhexyl) dithiophosphoric acid (DTPA), as both an ion carrier and a solvent, was demonstrated. The gelled membrane can be formed with the weight ratio between (MP) : (DTPA) as low as 1 : 99 or higher. The membrane is capable of selective separation of metal ions. © 1993 John Wiley & Sons, Inc.

Extraction chromatography with modified poly(vinyl chloride) and di(2-ethylhexyl)dithiophosphoric acid

A method for the preparation of packed-bed columns made of gelled beads is described. The stable gelled beads composed of dialkyldithiocarbamate- or dialkyldithiophosphate-substituted poly(vinyl chloride) and di(2-ethylhexyl)dithiophosphoric acid were capable of the selective separation of metal ions. The stoichiometries of Ag +/H + and Cd 2+/H + extraction were established to be 3:1 and 2:1, respectively. A simple model of Ag + extraction kinetics was correlated with the experimental data. The selectivity of metal separations in displacement and elution chromatography was demonstrated.

Stable silica gel-bound crown ethers. Selective separation of metal ions and a potential for separations of amine enantiomers

Stable silica gel-bound crown ethers. Selective separation of metal ions and a potential for separations of amine enantiomers

Selective separation of metal ions by use of chelate-forming resins prepared by modification of conventional anion-exchangers with spadns and orange II

Anion-exchangers loaded with SPADNS or Orange II or SPADNS + Nitroso-R salt are used for selective separation of bismuth and cadmium, which are then determined by AAS.

Sorption and permeation behaviour of metal thiocyanate complexes on cellulose acetate polymers

Various metal thiocyanate complexes in aqueous solution were sorbed on solid cellulose acetate polymers. The sorption selectivity increased in the order Zn 2+ ≫ Fe 3+ ≫ Cu 2+ ≫ Co 2+ ≫ Ni 2+. The sorption behaviour followed a Langmuir-type adsorption isotherm, and the maximum adsorption capacity was 6.1 × 10 −5 mole of complex per g of polymer under optimum conditions. The zinc species sorbed appear to be NH 4Zn(H 2O)(SCN) 3 or (NH 4) 2Zn(SCN) 4 according to analysis of the sorption equilibrium. The ion-association species formed by the complex zinc anion and the ammonium ion was supposed to be sorbed (or “extracted”) onto the polymer matrix. As an application of sorption of metal complexes, a new hyperfiltration process was proposed for selective separation of metal ions. Thus, a mixture of metal thiocyanate complexes was hyperfiltered through cellulose acetate membranes. Permeation of certain metal complexes was preferred, and the selectivity was found to be similar to the sorption selectivity. These findings lead to a generalized idea that hyperfiltration separation of ionic species, particularly anionic metal complexes, can be attained by using polymer membranes which selectively adsorb or extract such ionic species as ion-association complexes onto the polymer matrix.

Selective separation of metal ions by a chelating agent-loaded anion exchanger

Selective separation of metal ions by a chelating agent-loaded anion exchanger