Separation/Preconcentration of Zn(II), Cu(II), and Cd(II) by Saccharomyces carlsbergensis Immobilized on Silica Gel 60 in Various Samples

Abstract

This study presents a solid phase extraction procedure based on column biosorption of Zn(II), Cu(II), and Cd(II) ions on Saccharomyces carlsbergensis immobilized on silica gel 60. The analytes were determined by flame atomic absorption spectrometry (FAAS). The optimum conditions for the quantitative recovery of the analytes, including pH, amount of solid‐phase, eluent type and flow rate of sample solution were examined. The effect of interfering ions on the recovery of the analytes was also investigated. Under the optimum conditions, recoveries of Zn(II), Cu(II), and Cd(II) were 99±2%, 98±2%, and 100±2% at 95% confidence level, respectively for spiked water samples. The analytical detection limits for Zn(II), Cu(II), and Cd(II) were 1.14, 1.66, and 1.48 ng mL^?1, respectively. The validation of the method was checked by the analysis of standard reference material (Tea leaves GBW‐07605) and spiked water, samples. The proposed method was applied for the determination of analytes in green onion, parsley, dam water, lake water, and tap water samples. The analytes has been determined in real samples with relative error lower than 8% and relative standard deviation lower than 10%.     

The adsorption behavior of Cu(II), Pb(II), and Co(II) of ethylene vinyl acetate‐clinoptilolite nanocomposites

In this study, ethylene vinyl acetate (EVA) was mixed with clinoptilolite (C), a natural zeolite, to prepare EVA‐C nanocomposites. The films were characterized by SEM‐EDS, XRD, and FT‐IR, and heavy metal removal was studied using the batch technique. The effects of the initial pH value and concentration of solutions, contact time, and filler dosage on the adsorption capacity of the composites were investigated. To study the influence of pretreatment on the filler, clinoptilolite was activated using KCl, NaCl, and HCl. Adsorption results show that equilibrium was reached after 24 h, and that sorption reached its maximum at pH values between 5 and 7. The selectivity trend was observed to be Pb > Cu > Co, which was consistent for both single and mixed metal‐ion solutions. Pretreatment significantly increased adsorption capacity of the composite, but was dependent on the conditioning reagent. Nanocomposites filled with HCl‐activated particles demonstrated a high adsorption capacity of between 70 and 80% for all three metals, while KCl‐activated particles were the least efficient with a maximum adsorption capacity of 69% for Pb(II), 54% for Cu(II) and 48% for Co(II). The adsorption data were then fitted to both Langmuir and Freundlich isotherms over the entire concentration range, and the Langmuir isotherm showed a better fit of the experimental sorption data than the Freundlich isotherm. The results obtained show that this simple methodology which can be up‐scaled has great potential for the preparation of a wide variety of similar particle‐filled adsorbent nanocomposites in other environmental remediation applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Pyromellitic dianhydride‐modified β‐cyclodextrin microspheres for Pb(II) and Cd(II) adsorption

In this work, the pyromellitic dianhydride (PMDA)‐grafted β‐cyclodextrin (β‐CD) microspheres have been prepared for the removal of lead and cadmium metal ions in aqueous solution by a batch‐equilibration technique. The effects of the pH of the solution, contact time, and initial metal concentration were studied. The adsorption capacities for the two metal ions increase significantly as a large number of carboxyl groups are present on the microspheres surface. The equilibrium process is better described by the Langmuir isotherm than the Freundlich isotherm. The maximum adsorption capacities are 135.69 and 92.85 mg g^?1 for Pb(II) and Cd(II), respectively. Kinetic studies show good correlation coefficients for a pseudosecond‐order kinetic model, confirming that the sorption rate is controlled by chemical adsorption. The regeneration of the adsorbent can be carried out by treating the loaded microspheres with 0.2 (mol L^?1) HCl obtaining high desorption rate for the two metal ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and application of partially porous poly(styrene‐divinylbenzene) particles for lipase immobilization

Partially porous poly(styrene‐divinylbenzene) (PS‐DVB) particles in the micron size range were prepared by the method of multistep swelling and polymerization involving the use of polymeric porogens. Polystyrene (PS) seeds prepared by dispersion polymerization were expanded in particle size by absorbing styrene and initiator, and then polymerized to form polymeric porogen particles. The newly synthesized PS chains served as the porogens of the PS‐DVB particles, resulting from the copolymerization of styrene and divinylbenzene in the swollen polymeric porogen particles. PS‐DVB particles with a specific surface area of up to 34 m²/g and a pore volume of up to 0.15 cm³/g were obtained. The average pore diameter of PS‐DVB particles was in the range of 15–24 nm. An increasing amount of toluene used in the copolymerization step increased the pore volume and specific surface area. Lipase from Candida rugosa was immobilized on the prepared PS‐DVB by physical adsorption. The optimum temperature for enzymatic activity was increased and the thermal deactivation of enzyme in organic solvent was slowed down by the immobilization. However, compared with soluble enzyme, the immobilized lipase on PS‐DVB retained a less activity after the first stage deactivation, suggesting a possible change in the conformation of enzyme molecule by immobilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 39–46, 2001     

Synthesis and photovoltaic properties of two side‐chain polymeric metal complexes containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II)

Two novel side‐chain polymeric metal complexes (PF1 and PF2) containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II) having donor‐acceptor π‐conjugated structure have been synthesized and characterized using Fourier transform infrared, ¹H NMR, UV‐visible and photoluminescence spectroscopies, thermogravimetric analysis, differential scanning calorimetry, elemental analysis and cyclic voltammetry. Dye‐sensitized solar cells (DSSCs) based on PF1 and PF2 as the dye sensitizers exhibit good device performance with solar‐to‐electricity conversion efficiency up to 0.32% (J_sc = 0.83 mA cm^?2, V_oc = 0.62 mV and FF = 0.62) and 0.24% (J_sc = 0.69 mA cm^?2, V_oc = 0.59 mV and FF = 0.60), respectively, under simulated AM 1.5 G solar irradiation (100 mW cm^?2). The data show that these novel polymeric metal complexes are suitable for DSSCs. Copyright © 2012 Society of Chemical Industry     

Oxidation of 4‐nitrophenol in water over Fe(III), Co(II), and Ni(II) impregnated MCM41 catalysts

BACKGROUND: Nitrophenols are toxic constituents of the effluents of petroleum, textile, dye, iron and steel, foundries, pharmaceutical and electrical manufacturing industries. Aromatic nitro compounds are particularly resistant to normal chemical or biological oxidation making them environmentally persistent. Advanced oxidation using appropriate catalysts mineralize these organics to harmless final products. In this work, MCM41‐based catalysts incorporating Fe(III)‐, Co(II)‐ and Ni(II)‐ cations were used for oxidizing 4‐nitrophenol in water under variable conditions of reaction time, pH, mole ratio of the reactant and the oxidant, catalyst load, feed concentration, and temperature. RESULTS: The catalysts prepared were characterized with X‐ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), cation exchange capacity (CEC) and atomic absorption spectrometry (AAS) measurements. In typical reaction conditions of temperature 353 K, time 300 min, catalyst load 2 g L^?1 and 10^?3 mol L^?1 4‐nitrophenol, the oxidation was 48.7, 52.2 and 55.2% with H₂O₂ and 42.5, 56.6 and 60.2% without H₂O₂ for Fe(III)‐, Co(II)‐ and Ni(II)‐MCM41, respectively. Pseudo‐first‐order kinetics with kinetic constant of 2.0 × 10^?3 to 5.5 × 10^?3 Lg^?1 min^?1 was proposed along with a possible mechanism. 4‐nitrocatechol, 4‐nitropyrogallol, 1,2,4‐trihydroxybenzene, hydroquinone, acrylic acid, malonic acid, and oxalic acid were identified in the oxidation products. CONCLUSION: Introduction of Fe(III)‐, Co(II)‐ and Ni(II)‐ into MCM‐41 by impregnation produced effective catalysts for wet oxidation of 4‐nitrophenol. The catalysts were able to oxidize 4‐NP even without the presence of an oxidizing agent. The results suggest that the transition metal loaded MCM41 brings about a more effective interaction between 4‐NP molecules and OH radicals. Copyright © 2008 Society of Chemical Industry     

Synthesis,characterization, and properties of polychelates of poly(styrene sulfonic acid‐co‐maleic acid) with Co(II), Cu(II), Ni(II), and Zn(II)

Polymer metal complexes of poly(styrene sulfonic acid‐co‐maleic acid) and Cu(II), Ni(II), Co(II), and Zn(II) were synthesized. The magnetic, spectral, and thermal properties, as well as the electrical conductivities, of the chelates were investigated, and possible structures were assigned to the polychelates. Semiempirical calculations at the AM1 level were carried out on the geometrical arrangement of the polychelates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2546–2551, 2002     

Polarographic determination of the competitive adsorption of U(VI), Pb(II), and Cd(II) ions on poly(N‐vinyl‐2‐pyrrolidone‐g‐citric acid) hydrogels

Poly(N‐vinyl‐2‐pyrrolidone‐g‐citric acid) [P(VP‐g‐CA)] hydrogels were prepared for the removal of U(VI), Pb(II), and Cd(II) from aqueous solutions containing different amounts of these ions (2.5–10 mg/L). Different pHs (1–13), temperatures (20–40°C), and ionic strengths (0.5M) were also tried for the adsorption behavior of these ions. The competitive adsorption values of U(VI), Pb(II), and Cd(II) ions on pure poly(N‐vinyl‐2‐pyrrolidone) were low [0.71–2.03 mg of U(VI)/g of dry gel, 0.15–1.58 mg of Pb(II)/g of dry gel, and 0.10–0.68 mg of Cd(II)/g of dry gel]. The incorporation of citric acid significantly increased the adsorption of these ions [0.67–2.12 mg of U(VI)/g of dry gel, 0.44–1.88 mg of Pb(II)/g of dry gel, and 0.04–0.92 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐1; 0.71–2.36 mg of U(VI)/g of dry gel, 0.60–2.16 mg of Pb(II)/g of dry gel, and 0.14–0.80 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐2; and 0.79–2.47 mg of U(VI)/g of dry gel, 0.70–2.30 mg of Pb(II)/g of dry gel, and 0.20–0.86 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐3]. The observed affinity order of adsorption was U(VI) > Pb(II) > Cd(II) for competitive conditions. The optimal pH range for the removal of these ions was 5–9. Competitive adsorption studies showed that other stimuli, such as the temperature and ionic strength of the solution, also influenced the U(VI), Pb(II), and Cd(II) adsorption capacity of P(VP‐g‐CA) hydrogels. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2019–2024, 2003     

Cloud point and solvent extraction study of uranium(VI) by 8‐hydroxyquinoline

BACKGROUND: Cloud point extraction (CPE) is an attractive alternative to solvent extraction. However, comparisons between both techniques are lacking. In this paper, the extraction of uranium(VI) using 8‐hydroxyquinoline (HQ) as chelating agent was studied by CPE using Triton X‐114 as non‐ionic surfactant and by solvent extraction using CHCl₃ as diluent. RESULTS: Using CPE, a quantitative extraction was observed for pH higher than 4.5 with a HQ/U ratio of 10. Using solvent extraction an increase in the HQ/U ratio up to 50 is necessary to obtain a near quantitative extraction. Both extraction systems were then compared with respect to the nature of extracted species, and the extraction constants determined using log‐log analysis of the extraction data. In the solvent extraction system, the extracted species were identified as UO₂Q₂ and the corresponding extraction constant was found to be log k_ex = ? 3.6 ± 0.2 on the molar scale. Considering that UO₂Q₂ is also the extracted species in CPE, a slightly higher extraction constant, i.e. log k_ex = ? 2.5 ± 0.3, was found. CONCLUSION: Such a small difference in favour of the CPE system may arise from the combination of various phenomena, including effects of temperature and effects of ‘extractant environment’. However, a change in the nature of the extracted species, namely from UO₂Q₂ in the solvent extraction system to the formation of adducts, i.e. UO₂Q₂(HQ) and UO₂Q₂(HQ)₂ in the CPE system, due to higher HQ concentration in the surfactant‐rich phase compared with chloroform, cannot be precluded, but requires confirmation. Copyright © 2012 Society of Chemical Industry     

Enzymatic degradation of blends of poly(ε‐caprolactone) and poly(styrene‐co‐acrylonitrile) by Pseudomonas lipase

In polymer blends, the composition and microcrystalline structure of the blend near surfaces can be markedly different from the bulk properties. In this study, the enzymatic degradation of poly(ε‐caprolactone) (PCL) and its blends with poly(styrene‐co‐acrylonitrile) (SAN) was conducted in a phosphate buffer solution containing Pseudomonas lipase, and the degradation behavior was correlated with the surface properties and crystalline microstructure of the blends. The enzymatic degradation preferentially took place at the amorphous part of PCL film. The melt‐quenched PCL film with low crystallinity and small lamellar thickness showed a higher degradation rate compared with isothermally crystallized (at 36, 40, and 44°C) PCL films. Also, there was a vast difference in the enzymatic degradation behavior of pure PCL and PCL/SAN blends. The pure PCL showed 100% weight loss in a very short time (i.e., 72 h), whereas the PCL/SAN blend containing just 1% SAN showed ～50% weight loss and the degradation ceased, and the blend containing 40% SAN showed almost no weight loss. These results suggest that as degradation proceeds, the nondegradable SAN content increases at the surface of PCL/SAN films and prevents the lipase from attacking the biodegradable PCL chains. This phenomenon was observed even for a very high PCL content in the blend samples. In the blend with low PCL content, the inaccessibility of the amorphous interphase with high SAN content prevented the attack of lipase on the lamellae of PCL. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 868–879, 2002     

Synthesis and thermal studies of poly(N‐acryloyl,N′‐cyanoacetohydrazide) complexes with Co(II), Fe(III), and UO2(II) ions

Polymer complexes with uranium, cobalt, and iron chlorides were synthesized and investigated by elemental analysis, electronic (uv–visible), IR vibration, and magnetic moment measurements. The thermal stabilities of N‐acryloyl,N′‐cyanoacetohydrazide (ACAH) homopolymers and polymer complexes of poly(ACAH) (PACAH) with metal chlorides were studied thermogravimetrically. The rates of polymerization of PACAH in the absence and presence of metal chlorides were studied. The activation energies of the degradation of the homopolymer and polymer complexes were calculated using the Arrhenius equation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3354–3358, 2003     

Synthesis and characterization of polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene triblock copolymers by atom‐transfer radical polymerization

Well‐defined polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐PS triblock copolymers were synthesized by atom‐transfer radical polymerization (ATRP), using C—X‐end‐group PEO as macroinitiators. The triblock copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The experimental results showed that the polymerization was controlled/living. It was found that when the number‐average molecular weight of the macroinititors increased from 2000 to 10,000, the molecular weight distribution of the triblock copolymers decreased roughly from 1.49 to 1.07 and the rate of polymerization became much slower. The possible polymerization mechanism is discussed. According to the Cu content measured with atomic absorption spectrometry, the removal of catalysts, with CHCl₃ as the solvent and kaolin as the in situ absorption agent, was effective. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2882–2888, 2000     

Synthesis and characterization of water‐soluble oligosalicylaldehyde‐sulfanilic acid and its Cu(II), Co(II), Pb(II) complexes

This work presents the synthesis and characterization of a new water‐soluble oligophenol derivative, 4‐(2‐hydroxybenzylideneamino)benzenesulfanilic acid (OSAL‐SA) and its metal complexes. The chemical structure of the water‐soluble polymer was characterized by nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FTIR) spectroscopies and thermogravimetric analyses (TGAs). Pb(II), Cu(II), Co(II) complexes of the polymer were also synthesized in methanol. Characterizations of water insoluble polymer‐metal complexes were performed by FTIR, flame atomic absorption spectroscopy, and TGA. The conductivity measurements of OSAL‐SA and polymer–metal complexes were carried out by the four‐probe technique. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology,morphology, and mechanical properties

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Competitive adsorption of uranyl ions in the presence of Pb(II) and Cd(II) ions by poly(glycidyl methacrylate) microbeads carrying amidoxime groups and polarographic determination

The adsorption capacity of UO in the presence of Pb(II) and Cd(II) ions was investigated with amidoximated poly(glycidyl methacrylate) (PGMA) microbeads with an average size of 135 μm packed in a glass column (0.5‐cm i.d. and 20‐cm length, flow rate = 3 mL/min) under competitive conditions. A differential pulse polarography technique was used for the determination of trace quantities of uptaken elements by the measurement of the reduction peak currents at ?200/?950, ?400, and ?600 mV (vs a saturated calomel electrode) for UO, Pb(II), and Cd(II) ions, respectively. When only UO was found in the eluate, its adsorption was 85.3% from a 50 μM initial solution. However, when there was UO with binary systems of Pb(II) or Cd(II), it was 78.2 and 76.3%, respectively. On the other hand, in a ternary mixture of UO with Pb(II) and Cd(II), the adsorption was found to be 75.2% with the same initial concentration. According to the results, the competitive adsorption studies showed that these amidoximated PGMA microbeads had good adsorption selectivity for UO with the coexistence of Pb(II) and Cd(II) ions. The ionic strength of the solution also influenced the UO adsorption capacity of the amidoximated PGMA microbeads. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4168–4172, 2007     

Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)

Aromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001     

Preparation of poly(9‐aminoacridine)‐modified electrode and its application in the determination of dopamine and ascorbic acid simultaneously

A novel modified electrode was fabricated with 9‐aminoacridine by electropolymerization in the phosphate buffer solution (PBS) (pH 7.4) and was characterized by cyclic voltammetry (CV). The modified electrode showed excellent electrocatalytic effect and high stability toward the electrochemical oxidation of dopamine (DA) and ascorbic acid (AA). Also, it showed a high stability for the determination of DA and AA simultaneously. Well‐separated voltammetric peaks were observed for DA and AA on the modified electrode. The separation of two anodic peaks was 170 mV, which was large enough to eliminate the interference of AA and determine DA. The differential pulse voltammograms (DPV) were used for the measurement of DA by means of the poly(9‐aminoacridine)‐modified electrode in PBS at pH 7.4. A linear response toDA was observed in the concentration range from 1.5 × 10^?6 to 3.5 × 10^?3 mol L^?1 with a correlation coefficient of 0.9998 and a detection limit (S/N = 3) of 1.0 × 10^?7mol L^?1. The proposed method was used to determine DA in DA‐hydrochloride injection and showed excellent sensitivity and recovery. The ease of fabrication, good reproducibility, high stability, and low cost of the modified electrode are the promising features of the proposed sensor. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3864–3870, 2007     

Synthesis and properties of sulfonated poly(phosphazene)‐graft‐poly(styrene‐co‐N‐benzylmaleimide) copolymers via atom transfer radical polymerization for proton exchange membrane

A series of sulfonated poly(phosphazene)‐graft‐poly(styrene‐co‐N‐benzylmaleimide) (PP‐g‐PSN) copolymers were prepared via atom transfer radical polymerization (ATRP), followed by regioselective sulfonation which occurred preferentially at the poly(styrene‐co‐N‐benzylmaleimide) sites. The structures of these copolymers were confirmed by Fourier transform infrared (FTIR) spectroscopy, ¹H‐NMR, and ³¹P‐NMR, respectively. The resulting sulfonated PP‐g‐PSN membranes showed high water uptakes (WUs), low water swelling ratios (SWs), low methanol permeability coefficients, and proper proton conductivities. In comparison with non‐grafting sulfonated poly(bis(phenoxy)phosphazene) (SPBPP) membrane previously reported, the present membranes displayed higher proton conductivity, significantly improved the thermal and oxidative stabilities. Transmission electron microscopy (TEM) observation showed clear phase‐separated structures resulting from the difference in polarity between the hydrophobic polyphosphazene backbone and hydrophilic sulfonated poly(styrene‐co‐N‐benzylmaleimide) side chains, indicating effective ionic pathway in these membranes. The results showed that these materials were promising candidate materials for proton exchange membrane (PEM) in direct methanol fuel cell (DMFC) applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42251.