Sorption of Metal Ions on Acrylamidezirconium (IV) Arsenate and its Synthesis of PVC based Lead (II) Selective Electrode

Abstract

The adsorption of different metal ions on acrylamidezirconium (IV) arsenate has been studied. The effect of surfactant concentration (Tween 80‐R and Tritron X‐100) on sorption of different metal ions acrylamidezirconium (IV) arsenate was explored. The effect of experimental parameters such as contact time, temperature, and pH on adsorption of Pb²⁺ions was studied. The promising feature of the material is its specificity for Pb²⁺ ions. A new PVC based Pb²⁺ ion‐selective electrode using acrylamidezirconium (IV) arsenate as electro‐active material has been fabricated. The electrode works well over a wide range of concentration 1×10^?1 M–1×10^?7 M with a Nerstian slope of 30±1 mV per decade. The sensor shows the short response time of 20 seconds and can operate in the pH range of 2–7. The sensor can be used for the period of over 4 months with out deviation in response characteristics. The electrode has been successfully used as an indicator electrode for potentiometric titration of Pb²⁺ ions in solution against EDTA solution.     

Oxidation of iodide ions by means of cyclic voltammetry

From chronovoltammetric and cyclovoltammetric polarization curves three mechanisms of iodide ions have been established: 3I^? = I^?₃ + 2e,2I^?₃ = 3I₂ + 2e and 2I^? = I₂ + 2e under certain conditions of scan rate, concentration of iodide ions and area of electrode in the aqueous solutions KI (background solution 1 N Na₂SO₄) with half-wave potentials of 0.428, 0.489 and 0.507 V by silver/silver chloride electrode.     

Studies with inorganic ion exchange membranes—a membrane selective to strontium ion

Strontium tungstoarsenate membrane shows response for Sr²⁺ and can be used to determine the activity of these ions. The response time of the membrane is a few seconds and the potentials generated are reproducible. The membrane electrode can be used for one year without any drift in potentials. The membrane was found to be more selective to Sr²⁺ ions than to many other of univalent, bivalent and tervalent cations. Anions also show no interference.     

Radiation Preparation of Conducting Nanocomposite Membrane Based on (Copper/Polyacrylic Acid/Poly Vinyl Alcohol) for Rapid Colorimetric Sensor of Mercury and Silver Ions

In this study, poly acrylic acid/poly vinyl alcohol capped copper as nanocomposite membrane Cu–(PAAc/PVA) has been prepared using gamma radiation. Aqueous solution of 0.2 mol Cu²⁺ ions chemically reduction using ascorbic acid and PAAc/PVA as stabilizer. Cu²⁺ ions could be deposited uniformly on the matrix network of PAAc/PVA membrane. The resulting Cu–(PAAc/PVA) nanocomposites membrane exhibited rapid colorimetric detection of mercury and silver ions associated with notable color changes of the membrane from yellow to pale gray and dark green, respectively. A novel label colorimetric sensor membrane Cu–(PAAc/PVA) has been developed for sensitive detection of Hg²⁺, Ag⁺ ions basis of the UV spectrophotometer data. A detection limit as low as 10^?5 and 10^?6 M of Hg²⁺ and Ag⁺ ions was achieved. This article proved that the Cu–(PAAc/PVA) nanocomposites membrane is exhibited excellent selectivity toward Hg²⁺, Ag⁺ ions. The advantages to the determination of Hg²⁺, Ag⁺ ions using Cu(PAAc/PVA) nanocomposite membrane is simple, low cost, rapid and easy observation by naked eye, the developed Cu–(PAAc/PVA) colorimetric membrane candidate for the detection of toxic Hg²⁺, Ag⁺ ions in environmental and biological samples. The particles size of synthesized Cu was performed using Transmission electron microscopy (TEM) indicates that Cu nanoparticles of size 8 nm are formed by green method. Absorption spectra of Cu nanoparticles deposited in PAAc/PVA at 591 nm confirm the capped of Cu nanoparticles inside PAAc/PVA matrices. The synthesized Cu nanocomposite has been found to be more AC conducting at low frequency than Hg and Ag nanoparticles. The increasing increase in conductivity of membrane can be correlated due to the formation of localized electronic states in polymer matrix due to insertion of Cu nanoparticles.     

A potentiometric and voltammetric sensor based on polypyrrole film with electrochemically induced recognition sites for detection of silver ion

Conducting polypyrrole membranes were deposited on glassy carbon electrodes by electropolymerizing pyrrole in the presence of Eriochrome Blue-Black B (EBB) as the counter anion. The electrodes were then subjected to several oxidation/reduction potential steps in pure silver nitrate solution for successive accumulation/stripping of silver species. This electrochemically mediated doping/templating generated selective recognition elements in the EBB/PPy film for silver ions. The resulting sensor exhibited a considerable enhancement in the potentiometric and voltammetric response characteristics: extending the linear dynamic range and lowering the detection limit. In the potentiometric mode, the sensor showed highly reproducible response with a Nernstian slope of 58.5 ± 0.3 mV per decade of Ag⁺ activity over a linear range spanning seven orders of magnitude (1 × 10⁻⁸ to 1 × 10⁻¹ M Ag⁺), with a detection limit of ∼6 × 10⁻⁹ M. The electrodes demonstrated high selectivity over a large number of cations including alkali, alkaline earth and several transition and heavy metal ions, and could be used over a wide pH range of 1-8.5. The EBB/PPy modified electrode was also used for preconcentration and differential pulse anodic stripping voltammetric (DPASV) measurements. The DPASV peak current was dependent on the concentration of Ag⁺ over the range 3 × 10⁻¹⁰ to 1 × 10⁻⁴ M. The presence of 1000-fold excess of Cd²⁺, Cu²⁺, Cr³⁺, Co²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Ni²⁺ and Pb²⁺ can be tolerated in the determination of silver ion.     

Highly selective and sensitive Th<Superscript>4+</Superscript>-PVC-based membrane sensor based on 2-(diphenylphosphorothioyl)-<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-diphenylacetamide

A Th⁴⁺ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV per decade) over the concentration range 1.0 × 10⁻²–1.0 × 10⁻⁶ M. The detection limit of the electrode is 6.3 × 10⁻⁷ M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of Th⁴⁺ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture.     

Studies on an araldite-based membrane of copper hexacyanoferrate (III) as a caesium ion-sensitive electrode

Solid membranes of copper hexacyanoferrate (III) in araldite are evaluated as a caesium ion-sensitive electrode. The electrode can be used for caesium determination in the concentration range of 10⁻¹ to 10-⁴M . The potentials generated across the membrane are reproducible and steady potentials are attained in about 1 to 2min. The same electrode can be used over a period of 6 months without significant change in potential. The electrode can be used in the pH ranges 2.5–6.0 at 10⁻² M Cs⁺ and 3.0–6.0 at 10⁻³ M CS⁺, and in presence of a number of interfering ions. Potentiometric titration of caesium nitrate with 12-moIybdophosphoric acid was also carried out using the membrane as an end point indicator.     

Mesure de pO2− au moyen d'une electrode a membrane de zircone stabilisee et determination potentiometrique de constantes d'equilibre d'echange de O2− dans le melange equimolaire NaCl-KCl fondu

A galvanic cell with a Ag/AgCl reference electrode and a pO^2? indicating electrode—made of a solid-state membrane in zirconia stabilized by calcia and filled by a mixture of Ni + NiO—has been constituted for working in the molten mixture NaCl-KCl (1:1), from 700 to near 1000°C. The response of the zirconia electrode in the fused salt has been tested by known variations of pO^2?, due to coulometric titrations of free oxide ions, then of hydroxide ions, by means of metallic ions (Ni²⁺, Cu⁺) forming scarcely soluble metallic oxides. The results of measurements were in a good accordance with the variation laws theoretically established, giving the proof that measurements of pO^2?, between about 2 and 12, are possible in the electrolytic and temperature range considered, by means of this system. An alteration of the electrode can arise in media with too low a pO^2? value.Equilibrium constants have been determined: solubility products (K_s) of the oxides NiO and Cu₂O, constant values of the equilibria 2OH^? ? H₂O (g) + O^2? (K₁) and H₂O (g) + 2Cl^? ? O^2? + 2HCl (g) (K₂); as functions of the absolute temperature T/°K and in the molar fraction scale (partial pressure of the gazeous substances in atm):

The solubility product values (at 727°C) for a few metallic oxides have been calculated from the free enthalpy values of formation and experimental values of the activity coefficients of the metallic ions and O^2? dissolved in NaCl-KCl.Limitations to the ability of the membrane electrode for measuring pO^2? have been established by an analysis based on the chemical and electrochemical behaviour of zirconia. A potential-pO^2? diagram shows the area inside which one has to work.     

Reaction of Ozone with Ag(I)—Mechanistic Considerations

Ozone reacts slowly with Ag⁺ (circumneutral pH, k = (11 ± 3) × 10^?2 M^?1 s^?1). After some time, ozone decay kinetics may suddenly become faster with the concomitant formation of silver sol. As primary process, an O-transfer from O₃ to Ag(I) is suggested, whereby Ag(III) is formed [Ag⁺ + O₃ + 2 H₂O → Ag(OH)₃ + O₂ + H⁺]. This conproportionates with Ag(I), which is in large excess, leading to Ag(II) [Ag⁺ + Ag(OH)₃ ? 2 Ag(OH)⁺ + HO^?]. Further, Ag(II) reacts with ozone in a high exergonic reaction [Ag(OH)⁺ + O₃ → Ag + 2 O₂ + H⁺], where ozone acts as a reducing agent. Thereby, a single silver atom, Ag, is formed that can be oxidized by O₂ and O₃ or can aggregate to a silver sol. Aggregation slows down the rate of oxidation. When Ag⁺ is complexed by acetate ions, ozone decay and silver sol formation are speeded up by enhancing Ag(II) formation [Ag(I)acetate + O₃ → Ag(III)acetate → Ag(II) + CO₂ + ?CH₃]. In the presence of oxalate, the formed complex reacts faster with ozone than Ag⁺, and Ag(III)oxalate decarboxylates rapidly [Ag(I)oxalate + O₃ → Ag(III)oxalate → Ag⁺ + 2 CO₂]. This enhances ozone decay but prevents silver sol formation. Quantum chemical calculations have been carried out for substantiating mechanistic suggestions.     

Electrochemical sensors for the determination of Zn ions based on pendant armed macrocyclic ligand

The construction and performance characteristics of polymeric membrane electrodes based on two newly synthesized macrocyclic ligands 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,8,12,14-tetraene-9,12-N₂-1,5-O₂ (L₁) and 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,14-diene-9,12-dimethylacrylate-9,12-N₂-1,5-O₂ (L₂) for the quantification of Zn²⁺ ions are described here. Several membranes having different compositions of PVC, plasticizers, ionic additives and ionophores were fabricated and the best response was observed for the membrane having composition L₂:PVC:TBP:NaTPB in the ratio of 4:37:57:2 (w/w; mg). The response characteristics of the membrane based on L₂ were compared with polymeric membrane electrode (PME) as well as with coated graphite electrode (CGE). The electrode exhibits Nernstian slope for Zn²⁺ ions with limits of detection of 3.3 × 10⁻⁷ mol L⁻¹ for PME and 7.9 × 10⁻⁸ mol L⁻¹ for CGE with response time of 12 s and 10 s for PME and CGE respectively. Furthermore, the electrodes generated constant potentials in the pH range of 3.0–8.0 for PME and 2.5–9.0 for CGE. The practical utility of the CGE has been demonstrated by its usage as an indicator electrode in potentiometric titration of EDTA with Zn²⁺ ion solution. The high selectivity of CGE also permits their use in the determination of Zn²⁺ ions in water, biological, milk and tea samples.     

High temperature polarography in chloride melts with dropping electrodes

An experimental technique for polarographic studies with dropping electrodes at 1000°C in chloride melts was developed. Liquid silver and a gold-bismuth alloy were used as electrode materials for studying the reduction of Mn²⁺, Ag⁺ and Cu⁺ ions in molten KCl. Diffusion limited currents were observed for these ions but the halfwave potentials could not be determined because of corrosion reactions of the liquid metal electrode with the melt.     

Microfabrication, characterization and analytical application of a new thin-film silver microsensor

The present research demonstrates the microfabrication of a novel thin-film silver microelectrode based on an ion-selective PVC organic membrane. First, the gold substrate thin-film surface is treated by depositing a thin-layer of Ag electrochemically. This pretreatment step is followed by applying the organic-membrane-sensitive layer using a new nebulization technique, which gives a high stability to the organic-membrane-sensitive layer. The performance of the resulting thin-film silver microelectrode is investigated by potentiometric measurements. The microelectrode provides a linear Nernstian response of high sensitivity (58 ± 0.5 mV/decade) covering the range of 1 × 10⁻⁶-1 × 10⁻¹ mol L⁻¹ of Ag⁺ ions with a fast response time (<20 s) and a relatively long life span (>3 months). The suggested microelectrode is successfully used in the analytical evaluation of Cl⁻ ions in some real environmental samples as well as in the simultaneous determination of halides using potentiometric titration. The results obtained are compared with those obtained by the commercial silver billet electrode and the conventional bulk ion-selective electrode based on the same ionophore.     

Accumulation of Cu(II) cations in poly(3,4-ethylenedioxythiophene) films doped by hexacyanoferrate anions and its application in Cu-selective electrodes with PVC based membranes

Electrochemical properties of poly(3,4-ethylenedioxythiophene) doped with hexacyanoferrate(II,III) ions (PEDOT(HCF)) were studied in the presence of Cu²⁺ ions. Voltammetric and EDAX studies revealed retention of hexacyanoferrate anions in the polymer film and accumulation of Cu(II) cations, as well as formation of solid copper hexacyanoferrate near the polymer surface.Accumulation of Cu²⁺ ions was found to be advantageous from the point of view of PEDOT(HCF) applications as a solid contact (ion-to-electron transducer) in all-solid-state Cu²⁺-selective electrodes with solvent polymeric polyvinyl chloride (PVC) based membrane, containing Cu²⁺-selective ionophore. Binding of Cu²⁺ ions in the conducting polymer layer results in analyte ions flux into the transducer phase. Thus, pronounced enhancement of selectivity of the all-solid-state Cu²⁺-selective electrode or lower detection limit of the potentiometric response range was achieved, reaching under optimised conditions 10⁻⁷ M CuSO₄.     

Highly Selective Determination of Perchlorate by a Calix[4]arene based Polymeric Membrane Electrode

This article describes a versatile application of 25,27-bis-N-(N,N-diethyl-2-aminoethyl)carbonylmethoxy-26,28-dihydroxycalix[4]arene (4) as an ionophore for the preparation of perchlorate ion-selective electrode. The electrode exhibits a Nernstian response over the perchlorate concentration range of 1.0×10^?9 – 1.0×10^?1 M with a slope of 59.24 ± 0.5 mV per decade of the concentration. The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plot is 3.04×10^?9 M. The electrode shows good selectivity toward perchlorate with respect to many common anions. The response time of the sensor was 5–10 s and it has maximum life time of 2 months in the acidic pH. The electrode was used to determine perchlorate in real water samples. The interaction of the ionophore with perchlorate ions is also demonstrated by UV–vis spectroscopy.     

Construction of barium (II) PVC membrane electrochemical sensor based on 3-deoxy-d-erythro-hexos-2-ulose bis (thiosemicarbazone) as a novel ionophore

In this study, a new ion-selective electrode for Ba²⁺ is described, illustrating 3-deoxy-d-erythro-hexos-2-ulose bis (thiosemicarbazone) (DHUT) in a poly(vinylchloride) (PVC) membrane with benzyl acetate (BA) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic additive. This sensor presented very good selectivity and sensitivity towards the Ba²⁺ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The electrode revealed a great improvement in the selectivity coefficients for the Ba²⁺ ions in comparison with the formerly reported Ba²⁺ sensors. The proposed electrode exhibited a significantly enhanced response towards the Ba²⁺ ions across the concentration range of 1.0 × 10^− 6-1.0 × 10^− 2 M for the pH variation from 2.6 to 11 with a lower detection limit of 5.6 × 10^− 7 M. Moreover, the sensors displayed the Nernstian slope of 29.6 ± 0.5 mV per decade, having a fast response time within 15 s over the entire concentration range. It could also be used for at least 2 months with no potential divergence. As a result, the developed sensor was successfully applied to the direct barium ion determination in solutions, rock samples and as an indicator electrode in the Ba²⁺ ion potentiometric titration with EDTA.     

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.     

Electrochemical behavior of pyrite in sulfuric acid solutions containing silver ions

A systematic electrochemical study of pyrite in H₂SO₄ solutions containing dissolved silver was undertaken to gain more information about the transfer of silver ions to pyrite and their role in enhancing the direct oxidation of pyrite. The results of cyclic voltammetry experiments provide additional evidence of the formation of metallic silver on the FeS₂ surface under open-circuit conditions. A pyrite electrode held at the open-circuit potential for 2 h in the presence of 10^–3 m Ag⁺ exhibits a large and sharp anodic peak at about 0.7V. The current associated with this peak is the result of the dissolution of metallic silver deposited during the initial conditioning period. There is no evidence of silver deposition without preconditioning until the potential drops below about 0.6V for Ag⁺ concentrations ranging from 10^–4 to 10^–2 m. However, subsequent silver deposition appears to be very sensitive to the dissolved silver concentration in this range. There is also evidence that the state of the pyrite surface has a pronounced influence on its interaction with silver ions. Agitation has also been found to have a significant effect on the electrochemistry of the Ag–FeS₂ system.     

Novel coated graphite electrode for the selective determination of Gd(III) in rocks and waste water samples

A novel gadolinium selective coated graphite electrode based on 2,6-bis-[1-{N-cyanopropyl,N-(2-methylpridyl)}aminoethyl]pyridine [P] is described. The best performance was exhibited by the electrode having membrane composition P:NaTPB:PVC:NPOE as 8:4:30:58 (%, w/w). The electrode demonstrates excellent potentiometric characteristics towards gadolinium ion over several interfering ions. The electrode exhibited a Nernstian response to Gd³⁺ ion over a wide concentration range 2.8 × 10⁻⁷ to 5.0 × 10⁻² M with a detection limit (6.3 ± 0.1) × 10⁻⁸ M and slope 19.6 ± 0.1 mV decade⁻¹ of a_Gd³⁺. Furthermore, it showed a fast response time (12 s) and can be used for 2.5 months without significant divergence in its characteristics. Noticeably, the electrode can tolerate the concentration of different surfactants up to 1.0 × 10⁻⁴ M and can be used successfully in 30% (v/v) ethanol media and 10% (v/v) methanol and acetonitrile water mixture. The useful pH range of this sensor is 2.0 to 8.0. It is sufficiently selective and can be used for the determination of Gd³⁺ ions in waste water and rock samples. It also serves as a good indicator in the potentiometric titration of GdCl₃ with EDTA.     

Contribution a l'etude des effets catalytiques exerces par les composes soufres a l'electrode a gouttes de mercure. Cas de la thiouree

The influence of thiourea and some of its N-alkyl-derivatives on the reduction of various metallic cations (Ni²⁺, Co²⁺, Co²⁺) has been studied in neutral medium at the dropping mercury electrode. The polarographic curves exhibit kinetic prewaves reaching a 2^?_e amplitude at high concentration. In addition fairly large extra-currents can be detected at verynegative potentials. By resorting to classical and pulse polarography and to macro-electrolysis, it has been demonstrated that these currents are related to both the electroreduction of thiourea with production of sulphide and cyanide ions and catalytic discharge of water itself. The reaction mechanism is discussed in terms of the structure of the organic compound and the properties of the electrode metal surface, in connection with similar phenomena observed in the presence of thiocyanate ion (reduction of the thione group) and sulfur proteins (catalytic hydrogen evolution).     

Synthesis of single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchnager: Ion exchange studies and its application as ion‐selective membrane electrode for determination of Cd(II) ions

Single‐walled carbon nanotubes cerium(IV) phosphate composite cation exchanger was synthesized using sol−gel method. The ion‐exchange properties such as elution concentration, elution behavior and effect of temperature on ion exchange capacity were studied. The composite cation exchange material showed an ion‐exchange capacity (IEC) of 1.64 meq dry g⁻¹ of ion exchanger. The distribution studies revealed that the composite cation‐exchanger is highly selective for Cd(II) ions. The material was used as an electroactive component for the construction of a cadmium ion‐selective membrane electrode. The membrane electrode showed a Nernstian response for Cd(II) ions over a wide concentration range of 1 × 10⁻⁷−1 × 10⁻¹ M with a sub‐Nernstian slope of 27.429 mV per decade change in concentration of cadmium ions. The limit of detection was found to be 1 × 10⁻⁷ M. It possessed a fast response time 10 s and can be utilized for 130 days without any considerable divergence in response potential. The practical utility of membrane electrode was demonstrated by employing as an indicator electrode for the potentiometric titration of Cd(II) with ethylenediamine tetra acetic acid, disodium salt (EDTA). POLYM. COMPOS., 38:1005–1013, 2017. © 2015 Society of Plastics Engineers