A new way of synthesis nanohybrid cation‐exchanger applicable for membrane electrode

A novel polymeric composite namely, PANI‐PW/Ag (silver doped polyaniline phosphotungstate) was expediently obtained by sol‐gel method. PANI‐PW/Ag was characterized by Fourier transform infrared spectroscopy, X‐ray powder diffraction, UV–vis spectrophotometry, scanning electron microscopy, and thermogravimertic analysis. On the basis of ion exchange capacity and distribution studies, PANI‐PW/Ag, highly selective and sensitive to Cu(II), was used for the preparation of ion selective membrane for Cu(II). The electrode exhibits good potentiometric response for Cu(II) over a wide concentration range (1.0 × 10⁻¹−5.0 × 10⁻⁶ mol) with Nernstian slope of 27.8 mV per decade. Response time of the electrode is 9 s and it could be used for a period of 3 month and exhibits good selectivity toward Cu²⁺ in comparison to alkali, alkaline earth, transition, and heavy metal ions, with no interference caused by other heavy metals. POLYM. COMPOS., 35:1436–1443, 2014. © 2013 Society of Plastics Engineers     

Cation‐exchange kinetics and electrical conductivity studies of an ‘organic‐inorganic’ composite cation‐exchanger: Polypyrrole Th(IV) phosphate

Polypyrrole Th(IV) phosphate, an electrically conducting ‘organic‐inorganic’ cation‐exchange composite material was prepared by the incorporation of an electrically conducting polymer, i.e., polypyrrole, into the matrix of a fibrous type inorganic cation‐exchanger thorium(IV) phosphate. The composite cation‐exchanger has been of interest because of its good ion‐exchange capacity, higher chemical and thermal stability, and high selectivity for heavy metal ions. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using four‐in‐line‐probe dc electrical conductivity measuring instrument. The conductivity values lie in the semiconducting region, i.e., in the order of 10^?6 to 10^?4 S cm^?1 that follow the Arrhenius equation. Nernst–Plank equation has been applied to determine some kinetic parameters such as self‐diffusion coefficient (D₀), energy of activation (E_a), and entropy of activation (ΔS*) for Mg(II), Ca(II), Sr(II), Ba(II), Ni(II), Cu(II), Mn(II), and Zn(II) exchange with H⁺ at different temperatures on this composite material. These results are useful for predicting the ion‐exchange process occurring on the surface of this cation‐exchanger. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thorium (IV) phosphate‐polyaniline composite‐based hydrophilic membranes for bending actuator application

In the present study, ionic polymer metal composite (IPMC) membrane actuator based on triple‐layered thorium(IV) phosphate/polyaniline/Pt (ThP‐PANI‐Pt) was prepared via consecutive solution recasting and electroless plating methods. The triple‐layered membrane is composed of thorium(IV) phosphate (ThP) inorganic cation exchanger layer in the middle section, two layers of polyaniline deposited through in situ polymerization and finally Pt electrode layers on both the surfaces on the outer section. The water uptake capacity of the ThP‐PANI composite polymer membrane was found to be 95.40% at 45ºC for 10 h of immersion time. The ion exchange capacity and proton conductivity was found to be 1.6 meq g^?1of dry membrane and 1.12 × 10^?3 S cm^?1, respectively. Maximum water loss from IPMC was 38% at 4 V for a time period of 12 min. Scanning electron micrographs shows the smooth and uniform coating of Pt on both side of composite polymer membrane surfaces. Cyclic voltammetry, linear sweep voltammetry, transmission electron microscopy, Fourier transforms infrared spectroscopy, thermal gravimetric analysis, X‐ray diffraction, and tip displacement of ThP‐PANI‐Pt IPMC membrane actuator was also examined. POLYM. ENG. SCI., 57:258–267, 2017. © 2016 Society of Plastics Engineers     

Zinc selective nano‐hybrid cation exchanger carboxymethyl cellulose Zr(IV) tungstate: Sol‐gel synthesis,physicochemical characterization,and analytical applications

Nano‐hybrid cation‐exchanger, carboxymethyl cellulose Zr(IV) tungstate was synthesized in the presence of surfactant. Physicochemical properties like thermal stability, surface morphology, particle size, and composition were evaluated by using thermogravimetric analysis/diffrential thermal analysis/diffrential thermogravimetry (TGA/DTA/DTG), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission elctron microscopy (TEM), and energy dispersive X‐ray (EDX) techniques. The ion exchange properties such as ion exchange capacity, elution behavior, eluent concentration, thermal effects, and pH titration were also performed to validate ion exchange behavior of synthesized material. Incorporation of carboxymethyl cellulose into the matrices of inorganic gels of Zr(IV) tungstate resulted enhanced ion exchange capacity and better mechanical stability of nano‐hybrid cation exchanger. A series of experiments were carried out for selective separation of Zn(II) ions from aqueous solutions of two‐component mixtures of heavy metal ions such as Zn(II)‐Hg(II), Zn(II)‐Cd(II), Zn(II)‐Ni(II), and Zn(II)‐Mg(II). The distribution studies showed that the synthesized nano‐hybrid cation‐exchanger is highly selective to Zn(II) ions. POLYM. COMPOS., 38:2057–2066, 2017. © 2015 Society of Plastics Engineers     

In vitro cadmium removal from human serum by Cibacron Blue F3GA–thionein‐complex conjugated affinity membranes

A new membrane affinity biosorbent carrying thionein has been developed for selective removal of cadmium ions from human serum. Microporous poly(2‐hydroxyethyl methacrylate) (pHEMA) membranes were prepared by photopolymerization of HEMA. The pseudo dye ligand Cibacron Blue F3GA (CB) was covalently immobilized on the pHEMA membranes. Then, the cysteine‐rich metallopeptide thionein was conjugated onto the CB‐immobilized membrane. The maximum amounts of CB immobilized and thionein conjugated on the membranes were 1.07 µmol cm⁻² and 0.92 µmol cm⁻², respectively. The hydrophilic pHEMA membrane had a swelling ratio of 58% (w/w) with a contact angle of 45.8 °. CB‐immobilized and CB‐immobilized–thionein‐conjugated membranes were used in the Cd(II) removal studies. Cd(II) ion adsorption appeared to reach equilibrium within 30 min and to follow a typical Langmuir adsorption isotherm. The maximum capacity (q _m) of the CB‐immobilized membranes was 0.203 (µmol Cd(II)) cm⁻² membrane and increased to 1.48 (µmol Cd(II)) cm⁻² upon CB–thionein‐complex conjugation. The pHEMA membranes retained their cadmium adsorption capacity even after 10 cycles of repeated use. © 2000 Society of Chemical Industry     

Adsorption and electroanalytical studies of a poly‐o‐toluidine Zr(IV) phosphate nanocomposite for zinc(II) dimethyldithiocarbamate

The adsorption behavior of zinc(II) dimethyldithiocarbamate (Ziram) was studied on the surface of a poly‐o‐toluidine Zr(IV) phosphate nanocomposite cation exchanger. A spectrophotometric method based on the conversion of Ziram into a copper dimethyldithiocarbamate complex was applied for the study of Ziram at the maximum absorption wavelength of 437 nm. A Ziram‐ sensitive membrane electrode was fabricated with poly‐o‐toluidine Zr(IV) phosphate (an electroactive composite material). The sensitivity of Ziram for the composite cation‐exchange material was monitored with potentiometric methods. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sol–gel synthesis,physicochemical characterization,and analytical applications of copper selective composite cation exchanger: Polyvinyl alcohol Ce(IV) phosphate

An organic–inorganic composite cation exchanger polyvinyl alcohol Ce(IV) phosphate was prepared by the sol–gel method. The composite cation exchanger was characterized by some physicochemical properties like FTIR, TGA/DTA/DTG, XRD, SEM, TEM, EDX, and ion exchange properties to validate the structure and the ion exchange behavior. Ion exchange parameters indicated that the composite material is suitable for column operation. The ion exchange capacity of the composite ion exchanger is higher than that of the inorganic counterpart which showed that the incorporation of organic polymer polyvinyl alcohol (PVA) is responsible for prevention of the leaching of inorganic ion exchanger thereby proving mechanical stability and enhanced ion exchange properties. The distribution studies showed the selectivity toward Cu(II) ions, a heavy toxic metal ion. It was also observed that the selectivity depended upon the nature and composition of contacting solvents. The binary separation of a mixture of heavy metal ions Cu(II)–Zn(II), Cu(II)–Cd(II), and Cu(II)–Ni(II) also achieved thus composite cation exchanger proved excellent material could be effectively utilized in the treatment of discharge from copper plating, copper alloy, copper batteries, and smelting industries, whereas outstanding thermal stability of this composite ion exchanger could be utilized for the treatment of wastewater having Cu(II) ions with high temperature such as power generation and desalination plants. This composite ion exchanger with outstanding properties have potential to deal with aquatic toxicology caused by Cu(II) ions in future. POLYM. COMPOS., 38:332–340, 2017. © 2015 Society of Plastics Engineers     

Calcium ion-sensor based on polyindole-camphorsulfonic acid composite

We hereby report a new conducting polymer-based calcium ion exchanger, namely polyindole-camphorsulfonic acid (PIn-CSA) composite, and its application in the development of calcium ion-selective electrode. The processable PIn-CSA composite is developed by homogenizing equimolar ratio of chemically synthesized PIn and CSA in tetrahydrofuran. The homogenized PIn-CSA composite is cast over the Pt disc electrode under ambient conditions. The ion-sensor exhibits near Nernstian response for Ca²⁺ over a concentration range of 2 × 10⁻⁵ to 1 × 10⁻² M with a response time of 8 s. The sensor can be used for a period of over 3 months without any major drift in its baseline potential. The useful pH range of the ion-sensor was found out to be 4.0−8.0. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Metal‐chelating properties of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) membranes

Metal‐chelating membranes have advantages as adsorbents in comparison with conventional beads because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) [poly(HEMA–MAH)] membranes for the removal of three toxic heavy‐metal ions—Cd(II), Pb(II), and Hg(II)—from aquatic systems. The poly(HEMA–MAH) membranes were characterized with scanning electron microscopy and ¹H‐NMR spectroscopy. The adsorption capacity of the poly(HEMA–MAH) membranes for the selected heavy‐metal ions from aqueous media containing different amounts of these ions (30–500 mg/L) and at different pH values (3.0–7.0) was investigated. The adsorption capacity of the membranes increased with time during the first 60 min and then leveled off toward the equilibrium adsorption. The maximum amounts of the heavy‐metal ions adsorbed were 8.2, 31.5, and 23.2 mg/g for Cd(II), Pb(II), and Hg(II), respectively. The competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were 2.9 mg of Cd(II)/g, 14.8 mg of Pb(II)/g, and 9.4 mg of Hg(II)/g. The poly(HEMA–MAH) membranes could be regenerated via washing with a solution of nitric acid (0.01M). The desorption ratio was as high as 97%. These membranes were suitable for repeated use for more than three adsorption/desorption cycles with negligible loss in the adsorption capacity. The stability constants for the metal‐ion/2‐methacryloylamidohistidine complexes were calculated to be 3.47 × 10⁶, 7.75 × 10⁷, and 2.01 × 10⁷ L/mol for Cd(II), Pb(II), and Hg(II) ions, respectively, with the Ruzic method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1213–1219, 2005     

Fluorenyl‐containing Quaternary Ammonium Poly(arylene ether sulfone)s for Anion Exchange Membrane Applications

A series of anion exchange membranes (AEM) based on block quaternary ammonium poly(arylene ether sulfone) (QA‐bPAES) were successfully synthesized from 9,9′‐bis(4‐hydroxyphenyl) fluorene, 4,4′‐(hexafluoroisopropylidene) diphenol and 4,4′‐difluorodiphenyl sulfone via block polymerization, chloromethylation, quaternization, alkalization and solution casting. Properties of the obtained QA‐bPAES membranes, including ion exchange capacity (IEC), water uptake, swelling ratios, methanol permeability and ion conductivity were investigated. The obtained QA‐bPAES membranes showed low water uptakes, high ion conductivities and good physical and chemical stability. For example, the membrane of QA‐bPAES(20/10)‐1.34 with IEC of 1.34 mmol g⁻¹ exhibited swelling ratios of 5.0% and 5.1% in in‐plane and through‐plane direction, respectively, and ion conductivity of 15.6 mS cm⁻¹ in water at 60 °C with low methanol permeability of 1.06 × 10⁻⁷ cm² s⁻¹ (25 °C). All the results indicated that this type of block membranes had good potentials for alkaline anion exchange membrane fuel cell applications.     

Water‐sorption and metal‐uptake behavior of pH‐responsive poly (N‐acryloyl‐N′‐methylpiperazine) gels

Hydrogels based on N‐acryloyl‐N′‐methylpiperazine (AcrNMP) swelled extensively in solutions of low pH due to the protonation of the tertiary amine. The water transport in the gels under an acidic condition was non‐Fickian and nearly Fickian in neutral pH with the collective diffusion coefficients determined as 2.08 × 10⁻⁷ and 5.00 × 10⁻⁷ cm⁻² s⁻¹, respectively. These gels demonstrated good metal‐uptake behavior with various divalent metal ions, in particular, copper and nickel, with the uptake capacity increased with increasing pH. The swelling ratio of the gel in the presence of metal ions decreased with increasing metal ion uptake. The results suggest that high metal ion uptake can lead to physical crosslinking arising from the interchain metal complex formation. The metal‐loaded gels could be stripped easily with 1M H₂SO₄ without any loss in their uptake capacity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 268–273, 2001     

Studies on polycarbazole‐modified electrode and its applications in the development of solid‐state potassium and copper(II) ion sensors

Electrochemical synthesis of polycarbazole, having better stability and electrochromic activity, in dichloromethane containing 0.1 M tetrabutyl ammonium perchlorate (TBAP) is reported at 1.4 V versus Ag/AgCl. The electrochemistry based on cyclic voltammetric measurements in dichloromethane containing TBAP show redox behavior of the polymer associated to doping and de‐doping of ClO ion within the polymer interstices. The polycarbazole matrix obtained by the potentiostatic and potentiodynamic modes of electropolymerization is characterized based on scanning electron microscopy, differential calorimetry, and infrared spectroscopy. De‐doping of the polymer is studied by electrochemical reduction in TBAP‐free dichloromethane followed by incubation of the polymer film in 1 M aqueous KCl solution for 24 h. The open circuit potential (OCP) of doped and de‐doped polycarbazole modified electrode under the present experimental conditions is found to 462 and 19 mV, respectively, versus SCE in 0.1 M NH₄NO₃. The de‐doped polymer shows remarkable sensitivity and selective to Cu(II) ion compared to its sensitivity for Fe³⁺, Ni²⁺, Co²⁺, Pb²⁺, and Cu⁺ ions. A typical response of the de‐doped polymer electrode to Cu(II) ion is reported. On the other hand, ClO doped polymer is used in the development of solid‐state K⁺ ion sensors using dibenzo‐18‐crown‐6/valinomycin as a neutral carrier–based, plasticized poly vinyl chloride matrix membrane assembled over a polymer‐modified electrode. The doped polymer under this condition helps in maintaining charge stabilization across Pt/polymer and polymer/PVC interfaces. The lowest detection limit for the potassium ion sensor is 5 × 10⁻⁵ M with a slope of 58 mV/decade for valinomycin‐based sensor and 6.8 × 10⁻⁵ M with a slope of 54 mV for dibenzo‐18‐crown‐6 carriers with a wide linearity. The typical potentiometric results on the sensitivity, detection limits, and OCP to K⁺ ion recorded using present polymer are compared with the data recorded earlier using polyindole and a similar neutral carrier–based PVC membrane. A comparison on electrode kinetics of these two polymer‐modified electrodes also has been made using the data on Tafel plots to study the relative kinetic polarizability based on ion‐exchange currents. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1749–1759, 2000     

Zinc(II) modified carbon paste electrodes based on self-assembled mercapto compounds-gold-nanoparticles for its determination in water samples

In the present study newly developed potentiometric sensors for determination of zinc(II) are presented. The proposed potentiometric method was based on the fabrication of modified carbon paste (MCPE; electrode X) and modified gold nanoparticles-carbon paste (GNPs-CPE; electrode IX) sensors. A mercapto compound of 1,4-bis(5-mercaptopentyloxy)-benzene (BMPB) alone or self-assembled on gold nanoparticles was used as modifier to construct electrode (X) and electrode (IX) sensors, respectively. The prepared electrodes exhibit Nernstian slope of 29.93 ± 0.4 and 26.0 ± 1.02 mV decade⁻¹ towards Zn(II) ion over a wide concentration range of 6.8 × 10⁻¹⁰ to 2.9 × 10⁻² and 1.0 × 10⁻⁷ to 1.0 × 10⁻² mol L⁻¹ for electrode (IX) and electrode (X) sensors, respectively. The limit of detection of the electrode (IX) and electrode (X) sensors was found to be 6.8 × 10⁻¹⁰ and 1.0 × 10⁻⁷ mol L⁻¹, respectively. The potentiometric response of the electrode (IX) and electrode (X) based on GNPs-BMPB and BMPB are independent of pH of test solution in the pH range of 2.5–8.1 and 3–7 with a response time of 6 and 8 s for electrode (IX) and electrode (X) sensors, respectively. The proposed sensors showed fairly good discriminating ability towards Zn(II) ion in comparison with many hard and soft metal ions. Finally, the proposed electrodes were successfully used as indicator electrodes in potentiometric titration of zinc ion with sodium tetraphenylborate (NaTPB) and in direct determination of Zn(II) ion in some water samples. The results obtained compared well with those obtained using atomic absorption spectrometry.     

Fabrication of a novel holmium(III) PVC membrane sensor based on 4-chloro-1,2-bis(2-pyridinecarboxamido)benzene as a neutral ionophore

This paper introduces the development of an original PVC membrane electrode, based on 4-chloro-1,2-bis(2-pyridinecarboxamido)benzene (CBPB) as a suitable carrier for the Ho³⁺ ion. The electrode presents a Nernstian slope of 19.7 ± 0.3 mV per decade for the Ho³⁺ ions across a broad working concentration range from 1.0 × 10⁻⁶ to 1.0 × 10⁻² M. The lower detection limit was 8.5 × 10⁻⁷ M in the pH range 2.7–9.8, while the response time was rapid (<15 s). Therefore, this potentiometric sensor displayed good selectivity for a number of cations such as alkali, alkaline earth, transition and heavy metal ions. The practical applicability of the electrode was demonstrated by its use as an indicator electrode in the potentiometric titration of Ho³⁺ ions with EDTA and in the determination of F^- in mouth wash samples.     

Ion Exchange Kinetics of Heavy Metal Ions on Organic–Inorganic Composite Cation Exchanger Poly-o-toluidine Zr(IV) Tungstate

To study the ion exchange kinetics of heavy metal ions on the organic–inorganic composite cation exchanger poly-o-toluidine Zr(IV) tungstate, Nernst–Planck was computer simulated. Simulated numerical results for counter ions (Cu, Zn, Cd and Pb) of equal valence and four different ionic mobilities are presented to understand the ionic diffusion process. These results are based on the fractional attainment of equilibrium U(τ), of the counter ions under study. The forward (M²⁺–H⁺) and reverse (H⁺–M²⁺) ion exchange processes are justified as the particle diffusion phenomenon. The self-diffusion coefficient (D _o ), energy of activation (E _a ), and entropy of activation (?S*) have also been estimated to understand the ion exchange process occurring over the surface of this cation exchanger and indicated that the ion exchange process is feasible and spontaneous. It is concluded that the difference in activation energies and entropy of activation may facilitate the separation of metal ions. The regeneration capability of this cation exchanger was also explained.     

EDTA-stannic(IV)iodate: preparation, characterization and its analytical applications for metal content determination in real and synthetic samples

A new organic–inorganic cation exchanger EDTA-stannic(IV)iodate was synthesized. The materials possess good chemical and thermal stability. The exchanger was characterized on the basis of X-ray, TGA, FTIR, UV–Visible spectrophotometery and SEM studies. ion exchange capacity, pH titration, elution and distribution studies were also carried out to determine the primary ion exchange properties of the material. The SEM study confirms the fibrous nature of the material. The exchanger behaves as a monofunctional cation exchanger with ion exchange capacity of 1.30 meq/g for Na⁺ ions. The material can perform well upto the temperature of 500 °C and retains the 76.4% of ion exchange capacity. The material is fairly stable in dilute solutions of some common mineral acids, bases and organic solvents. The differential selectivity of metal ions on EDTA-stannic(IV)iodate has been utilized to perform analytically and industrially important binary separations.     

Potentiometric Determination of Alkyl Dimethyl Hydroxyethyl Ammonium Surfactant by a New Chemically Modified Carbon Past Electrode

This paper introduces the development a new chemically modified carbon paste electrode (CMCPE) for the determination of a cationic surfactant. The paste is based on alkyl dimethyl hydroxyethyl ammonium chloride (ADHACl) with phosphomolybdic acid as an ion‐exchanger (ADHA‐PM). The electrode exhibits a Nernstian slope of 59.1 ± 0.5 mV/decade for ADHA ions in the concentration range 1.0 × 10^?6–1.0 × 10^?3 M with the limit of detection of 8.2 × 10^?7 M. The proposed electrode has a fast and stable response time of 5–8 s, a good reproducibility and it can be used in the pH range of 2.2–9.0. Selectivity coefficients, determined by a matched potential method and separate solution method, showed high selectivity for ADHA over a large number of inorganic cations and organic cations. These characteristics of the electrode enable it to be used successfully for determination of ADHA in shampoo and liquid detergents solutions by standard addition and the calibration curve methods. In addition, the modified electrode was applied as an indicator electrode in potentiometric titration and successfully used to determine ADHA in water samples with satisfactory results.     

EB‐crosslinked Polymer Electrolyte Membranes Based on Highly Sulfonated Poly(ether ether ketone) and Poly(vinylidene fluoride)/Triallyl Isocyanurate

In this study, crosslinked polymer electrolyte membranes for polymer electrolyte membrane fuel cell (PEMFC) applications are prepared using electron beam irradiation with a mixture of sulfonated poly(ether ether ketone) (SPEEK), poly(vinylidene fluoride) (PVDF), and triallyl isocyanurate (TAIC) at a dose of 300 kGy. The gel‐fraction of the irradiated SPEEK/PVDF/TAIC (95/4.5/0.5) membrane is 87% while the unirradiated membrane completely dissolves in DMAc solvent. In addition, the water uptake of the irradiated membrane is 221% at 70 °C while that of the unirradiated membrane completely dissolves in water at above 70 °C. The ion exchange capacity and proton conductivity of the crosslinked membrane are 1.57 meq g⁻¹, and 4.0 × 10⁻² S cm⁻¹ (at 80 °C and RH 90%), respectively. Furthermore, a morphology study of the membranes is conducted using differential scanning calorimetry and X‐ray diffractometry. The cell performance study with the crosslinked membrane demonstrates that the maximum power density is 518 mW cm⁻² at 1036 mA cm⁻² and the maximum current density at applied voltage of 0.4 V is 1190 mA cm⁻².     

Controllable preparation and heavy‐metal‐ion adsorption of lignosulfonate‐polypyrrole composite nanosorbent

Lignosulfonate‐polypyrrole (LS‐PPY) composite nanospheres were prepared facilely via an in situ polymerization of pyrrole monomers in the presence of lignosulfonate as a dispersant and ammonium persulfate as an oxidant. The LS‐PPY composite was characterized with Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis, wide‐angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), field‐emission SEM, and transmission electron microscopy. Uniform LS‐PPY solid composite nanospheres with an average diameter of 154 nm were obtained. The LS‐PPY composite nanospheres were applied to adsorption of Ag(I) and Pb(II) ions from aqueous solutions. Maximum adsorption capacities of Ag(I) and Pb(II) were up to 759.3 mg g⁻¹ and 207.5 mg g⁻¹, respectively. Furthermore, the silver ions can be reduced to metallic silver nanowires through a redox reaction between the LS‐PPY composite nanospheres and the silver ions. A productive no‐template route to fabrication of LS‐PPY composite nanospheres with controllable size and heavy‐metal‐ion adsorption ability was achieved. POLYM. COMPOS., 36:1546–1556, 2015. © 2014 Society of Plastics Engineers     

ELECTRO-DEIONIZATION OF Cr (VI)-CONTAINING SOLUTION. PART II: CHROMIUM TRANSPORT THROUGH INORGANIC ION-EXCHANGER AND COMPOSITE CERAMIC MEMBRANE

Cr (VI) transport through a composite ceramic membrane containing an ion-exchange component, namely xerogel of hydrated zirconium dioxide, was investigated. The diffusion coefficient of Cr (VI) species through the membrane, which has been determined under open circuit conditions, is 1.80 × 10^?10 m² s^?1. The transport number of Cr (VI) species through the ceramic membrane was found to rise with increasing voltage and reached 0.17 under “over-limiting current” conditions. On the other hand, the transport of chromate ions through hydrogel of hydrated zirconium dioxide becomes more intensive with a decrease in potential drop through the system involving ion-exchanger bed and ceramic membrane due to decrease in the membrane resistance. The diffusion coefficient of Cr (VI) ions in hydrogel of the inorganic ion exchanger was estimated as 4.36 × 10^?12 m² s^?1. A possibility of Cr (VI) removal from a weakly acidic diluted solution using an electro-deionization method was shown: the degree of solution purification was found to reach 50%. The transport of species is realized through both the solution and the ion exchanger.