Poly Vinyl Chloride Membrane Research Articles

Development of calcium-selective potentiometric electrode using 10,19- Bis[(octadecylcarbamoyl)methoxyacetyl]-1,4,7,13,16-pentaoxa-10,19- diazacycloheneicosane compound as ionophore

This work deals with the development of micro-size potentiometric calcium-selective electrode. A simple and rapid potentiometric method of determining calcium concentration, based on 10,19-Bis[(octadecylcarbamoyl) methoxyacetyl]- 1,4,7,13,16–pentaoxa-10,19-diazacycloheneicosane, is described. For this aim, calcium-selective polyvinylchloride (PVC) membrane was prepared by coating on the surface of solid-contact. Calcium-selective PVC membrane electrode does not contain internal reference electrode and solution. The potentiometric performance of calcium-selective PVC membrane electrode (selectivity constant, liner working range, detection limit, response time, pH working range, repeatability, lifetime, and time dependent potential decay) was determined using computer controlled measurement system in static conditions. The results showed that the calcium-selective electrode exhibited good reproducibility in calcium determination.

A novel microbial fuel cell incorporated with polyvinylchloride/4A zeolite composite membrane for kitchen wastewater reclamation and power generation

Abstract The present work focuses on the synthesis of novel membrane based on hydrophilic zeolite 4A incorporated in hydrophobic polyvinylchloride (PVC) matrix for the treatment of kitchen wastewater by the microbial fuel cell (MFC). The indigenous membrane was prepared by solution casting-solvent evaporation technique and characterized by FTIR, XRD, TGA and SEM analysis. Sorption behavior, proton conductivity, ion exchange capacity (IEC) and MFC performance were thoroughly investigated. A molecular dynamics (MD) simulation was performed to determine oxygen diffusion coefficient through the membrane, which was found to be desirably low. Higher proton conductivity values were observed at increasing zeolite concentrations in PVC membrane until an optimum power density of 250 ± 5 mW m−2 could be achieved at 15% loading. Corresponding performances of plain PVC and Nafion 117 membranes were observed to be only 92 ± 5 mW m−2 and 125 ± 5 mW m−2, respectively. Furthermore, the PVC/4A membrane exhibited substantial removal of chemical oxygen demand up to an extent 89%. The mixed matrix membrane exhibits vast potential for MFC application as demonstrated by its performance comparison with state-of-the-art Nafion 117 membrane.

Facile Synthesis and Characterization of 5-[(3-Methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole and Its Potentiometric Sensor Application in a Polyvinyl Chloride Membrane for the Determination of Copper(II)

A novel Schiff base designated as 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole was synthesized and characterized. A polyvinyl chloride-membrane potentiometric copper(II)-selective sensor was prepared by using the synthesized 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole compound. The prepared polyvinyl chloride-membrane copper(II)-selective sensor exhibited very good selectivity and sensitive potentiometric response towards copper(II) ions compared to a wide variety of other cations. The sensor had a fast response time of <5 s, and showed a linear Nerstian behavior to copper(II) ions over a wide concentration range from 1.0 × 10−5 to 1.0 × 10−1 mol L−1 with a slope of 29.2 ± 0.7 and correlation coefficient of 0.9998. The prepared polyvinyl chloride-membrane copper(II)-selective sensor was used for 14 weeks without any significant change in its potentiometric response. The potentiometric response of the developed sensor was highly repeatable. Additionally, the developed sensor was used as an indicator electrode for the potentiometric titration of copper(II) ion with ethylenediaminetetraacetic acid. The sensor was also successfully applied to the direct determination of copper(II) ions in tap water, river water, and dam water samples.

Fresnel zone plate fabricated using a polyvinyl chloride gel

Based on creep-induced deformation of a polyvinyl chloride (PVC) gel in an electric field, a Fresnel zone plate (FZP) is fabricated. The employed electrode is constructed with a series of concentric zones, and the soft PVC gel coated on the electrode forms a flat membrane. By applying a DC voltage to the electrode, electrons are injected to the PVC gel. Due to the generated electrostatic force, the surface of the PVC membrane is undulated. The configuration of the PVC membrane resembles the pattern of the electrode. As a result, the PVC membrane functions as an FZP. The results show that incident light passing through the FZP can be diffracted, producing a focused spot due to constructive interferences. The maximum diffraction efficiency can reach ∼32.5 % , and the focal length is switchable. The advantages of this FZP are the ease of manufacturability, compactness, large size, and optical isotropy.

Reactive modification of PVC membranes for the improved performance

Poly vinyl chloride (PVC) was chemically modified, and used for ultrafiltration to analyze the performance. Nonsolvent induced phase separation (NIPS) method was used to prepare membranes. The neat PVC membrane was casted and used as a control membrane. Modified membrane was prepared by reacting PVC with ethanolamine (EA) in the casting solution (labeled as CM-PVC). Pure water permeability (PWP) was evaluated by measuring pure water flux. Humic acid was used as model foulant solute to analyze flux and rejection ability of membranes. Flux and rejection data of neat and modified membranes were compared to prove the improvement in the filtration performance. The experimental results showed that for PVC and CM-PVC, PWP was calculated to be ~64 and ~143 L/m2.h, respectively, and the rejection of humic acid was found to be 98% and 100%, respectively. TGA was carried out to analyze the effect of chemical modification on the thermal stability of polymer. FT-IR analysis was another characterization technique used for the comparative study.

CO2/N2 Separation Using Polyvinyl Chloride Iso-Phthalic Acid/Aluminium Nitrate Nanocomposite Membrane

In this paper, composite membranes based on polyvinyl chloride (PVC) has been prepared and then filled with 0.125-0.250 wt% of iso-phthalic acid/aluminium nitrate nanoparticles. All of the polymeric and nanocomposite membranes were fabricated by solution casting using tetrahydrofuran (THF) solvent. The performance of the prepared membranes was studied for CO2/N2 at the feed pressure of 2.5, 3, and 3.5 bar at 35 °C. Results showed that in most cases, increasing the percentage of PVC increased the permeability of CO2/N2. Also, with the addition of iso-phthalic acid/aluminium nitrate nanoparticles in the membrane, gas permeability in all cases increased. The highest gas pair selectivity for CO2/N2 could be obtained from PVC (30 wt%) loaded with 0.250 wt% of iso-phthalic acid/aluminium nitrate nanoparticles. For characterization of samples, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used. These results also suggest that PVC membranes with the higher loading percentage of nanoparticles are good candidates for the CO2/N2 separation, offering better selectivity for CO2/N2 in the range of 63.78 to 230.42, depending on the loading percentage.

An integrated ion-selective optode sensor cartridge for directly detecting electrolyte ions in blood plasma without pretreatment to adjust pH

We present a new integrated optode sensor cartridge that directly detects potassium, sodium, and chloride ions in blood plasma without pretreatment to adjust pH. Each optode sensor mainly consists of two separate layers, the optode and a dried buffer, which work by introducing plasma without blood cells filtered by a membrane filter. The optode layer uses a neutral ion-selective optode that is composed of an ionophore, a pH indicator dye (chromoionophore), and ionic additives incorporated in a plasticized polyvinyl chloride membrane. The dried buffer layer, which dissolves on contact with plasma, is applied to the optode layer, resulting in the constant pH of the plasma within the optode membrane. We determined the pHs of each dried buffer (potassium, sodium, and chloride) layer to be 7.0, 6.0, and 4.5, respectively, based on the pKa of their corresponding chromoionophores and effective buffer ranges. Consequently, the sensor responses varied as a function of the potassium, sodium, and chloride ion concentrations. To validate the accuracy of the ion-selective optode sensors, we investigated the correlations of potassium, sodium, and chloride ion concentrations with a commercial system (cobas® 8000) and observed comparable agreement between the two systems with correlation coefficients of 0.976, 0.955, and 0.966, respectively.

A novel amperometric bienzymatic biosensor based on alcohol oxidase coupled PVC reaction cell and nanomaterials modified working electrode for rapid quantification of alcohol

A new amperometric sensor has been fabricated for sensitive and rapid quantification of ethanol. The biosensor assembly was prepared by covalently immobilizing alcohol oxidase (AOX) from Pichia pastoris onto chemically modified surface of polyvinylchloride (PVC) beaker with glutaraldehyde as a coupling agent followed by immobilization of horseradish peroxidase (HRP), silver nanoparticles (AgNPs), chitosan (CHIT), carboxylated multi-walled carbon nanotubes (c-MWCNTs) and nafion (Nf) nanocomposite onto the surface of Au electrode (working electrode). Owing to properties such as chemical inertness, light weight, weather resistance, corrosion resistance, toughness and cost-effectiveness, PVC membrane has attracted a growing interest as a support for enzyme immobilization in the development of biosensors. The amperometric biosensor displayed optimum response within 8 s at pH 7.5 and 35°C temperature. A linear response to alcohol in the range of 0.01mM–50 mM and 0.0001 µM as a minimum limit of detection was displayed by the proposed biosensor with excellent storage stability (190 days) at 4°C. The sensitivity of the sensor was found to be 155 µA mM−1 cm−2. A good correlation (R2 = 0.99) was found between alcohol level in commercial samples as evaluated by standard ethanol assay kit and the current biosensor which validates its performance.

Graphene nanoplatelets in potentiometry: A nanocomposite carbon paste and PVC based membrane sensors for analysis of Vilazodone HCl in plasma and milk samples

Graphene is the ''new star'' material for electrochemical sensing. It has unique mechanical, thermal and electrical properties, in addition to its ultra light weight. In the present work we combine for the first time the special features offered by graphene and the advantages of ion selective potentiometric sensors in a single study. We propose two types of sensors, a graphene based carbon paste and a poly vinyl chloride (PVC) based membrane sensors for the analysis of Vilazodone hydrochloride in bulk, human plasma and formula milk samples. Electro active agent is an ion- association complex based on coupling of Vilazodone cationic cite with anionic cite of Molybdate ion in a ratio 1:1. Both sensors are evaluated according to the IUPAC recommendation data, revealing linear response in the concentration range 10−7 − 10−3 and10−8 − 10−3 M with a Nernestian slope 59.89 and 59.91 mV/decade for PVC membrane and Carbon paste sensors, respectively. Both sensors were successfully applied to the analysis of Vilazodone HCl in human plasma and formula milk samples showing good recovery percentage values. Graphene based carbon paste sensor shows several advantages over conventional PVC membrane sensor regarding lower limit of detection, faster response time, longer life time and higher selectivity towards target ion.

INFLUENCE OF THE NATURE OF TRIFLUOROACETOPHENON DERIVATIVES ON SELECTIVITY OF SULFATE AND CARBONATE-SELECTIVE ELECTRODES

UV-spectrophotometric and chromatographic studies of the distribution of trifluoroacetophenone (TFAF) and a number of its derivatives (heptyl ether of p-trifluoroacetylbenzoic acid (HE p-TFABA), p-methyltrifluoroacetophenone (p-MTFAF), 2,4-dimethyltrifluoroacetophenone (DMTFAF), 2,4,6-trimethyltrifluoroacetophenone (TMTFAF)) in a hexane-water system, which simplifies the modeling of a polyvinyl chloride membrane carbonate and sulfate-selective electrodes, were performed. These substances are used as neutral carriers (NC) in membranes of ion-selective electrodes, reversible to double-charged inorganic anions. A systematic study of the hydration of TFAF and a number of its derivatives was carried out. TFAF has increased solubility in water (the distribution coefficient D is 415) as compared to p-MTFAF, DMTFAF, TMTFAF and HE p-TFABA (D within 1360–2700), which does not allow to recommend it as an NC for making electrode membranes. The strongest hydration occurs for the HE p-TFABA in the alkaline medium. It has been found that p-MTFAF and HE p-TFABA form crystalline hydrates. The selectivity coefficients of carbonate and sulfate-selective electrodes were determined for all the NC studied and a number of them were made to improve the selectivity of the electrodes: TFAF k p-MTFAF k DMTFAF k TMTFAF k p-BTFAF (p-buthyltrifluoroacetophenone) k HE p-TFABA.

In-situ modification of PVC UF membrane by SiO 2 sol in the coagulation bath during NIPS process

Polyvinyl chloride (PVC) ultrafiltration (UF) membrane was modified by silica sol in the coagulation bath during non-solvent induced phase separation (NIPS) process. The effects of silica sol concentrations on the morphology, surface property, mechanical strength and separation property of PVC UF membranes were systematically investigated. PVC membranes were characterized by Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), contact angle goniometry and tensile strength measurement. The results showed that silica had been successfully assembled on the surface of PVC UF membrane. With the increase of silica sol concentration in the coagulation bath, the morphologies of PVC UF membranes changed from cavity structure to finger-like pore structure and asymmetric cross-section structure. The hydrophilicity and permeability of PVC UF membranes were further evaluated. When silica sol concentration was 20 wt.%, the modified PVC membrane exhibited the highest hydrophilicity with a static contact angle of 36.5 degree and permeability of 91.8 (L.m-2.h-1). The structure of self-assemble silica had significant impact on the surface property, morphology, mechanical strength and resultant separation performance of the PVC membranes.

Polyvinyl chloride (PVC) ultrafiltration membrane fouling and defouling behavior: EDLVO theory and interface adhesion force analysis

To unravel fouling and defouling mechanisms of protein, saccharides and natural organic matters (NOM) on polymeric membrane during filtration, this study investigated filtration characteristics on polyvinyl chloride (PVC) ultrafiltration membranes with bovine serum albumin, dextran, humic acid as model foulants. Membrane fouling and defouling performances were analyzed through monitoring the flux decline during filtration and flux recovery during physical backwash. Physico-chemical properties (e.g., hydrophobicity and surface charge) of PVC membrane and foulants were characterized, which were used in the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory to calculate the interaction energies between membrane-foulant and foulant-foulant. The results showed that at the later filtration stages the fouling rate was strongly correlated with the deposition rate, which was determined by the interaction energy profile calculated by EDLVO. Moreover, the adhesion forces of membrane–foulant and foulant–foulant were further measured by atomic force microscopy (AFM) with modified colloidal probes. A positive correlation (R2 = 0.845) between particle detachment rate (determined by adhesion force) and defouling rate was developed for BSA and HA foulants that led to cake layer formation. By contrast, dextran defouling rate was off this correlation as dextran partially clogged membrane pores due to its smaller size.

Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127.

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane. Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Computational and experimental approaches for investigating membranes diffusion behavior in model diesel fuel

Genetic algorithms trained support vector regression predicting model is conducted to research diffusion behavior of methylnaphthalene and dibenzothiophene in four different membranes of polymethyl methacrylate, polymethyl acrylate, polyvinyl chloride and polyvinyl alcohol in model diesel fuel. It is found that the polyvinyl chloride is optimal membrane material for improving the diffusion selectivity of methylnaphthalene and dibenzothiophene, which demonstrates that the polyvinyl chloride membrane is favorable to the diesel fuel desulfurization. Also, molecular dynamic simulation is applied to validating the performance of genetic algorithm trained support vector regression model. The results of genetic algorithm trained support vector regression model reveal that the simulation values are well agreed with the experimental data and molecular dynamic simulation results. Meanwhile, the performance of the genetic algorithms trained support vector regression predict model is better than that of the genetic algorithms trained neural network model, which indicates that genetic algorithms trained support vector regression method offers a new prospected decision-theoretic approach to the diesel desulfurization.

Synthesis, characterization and performance studies of mixed-matrix poly(vinyl chloride)-bentonite ultrafiltration membrane for the treatment of saline oily wastewater

Abstract The present study deals with the improvement of surface morphology, hydrophilicity and antifouling behavior of polyvinyl chloride (PVC) membrane by adding bentonite for ultrafiltration of oil-in-water emulsion under wide range of salinity (0–35000 ppm). Flat-sheet UF membranes were prepared by phase inversion technique using N, N-dimethylacetamide (DMAc) and water. Viscoelastic properties of the membrane casting solution were measured to fix sonication frequency, membrane casting speed and casting solution composition. Field-emission-scanning-electron-microscope and atomic-force-microscope were used to measure surface-porosity, pore-size distribution, pore density and roughness parameters of the membranes. Hydrophilicity of the membranes was determined by measuring equilibrium water content, contact angle and work of adhesion, whereas antifouling character was quantified by flux recovery ratio using saline oily-wastewater. Casting solution with PVC:DMAc:bentonite = 12.0:87.23:0.77 (i.e., PVC/bentonite-6) exhibited the maximum loss tangent and in-phase dynamic viscosity and resulted enhanced surface porosity (56.42–58.62%), root mean square surface roughness (127.6 nm), surface pore density (42.29–32.05 pores μm−2), hydrophilicity (work-of-adhesion:111.08 mN m−1) and antifouling character (flux-recovery-ratio:81.97%). PVC/bentonite-6 also delivered improved performance to separate oily-wastewater with zero salinity (oil rejection: 97.0% and permeate flux: 186 L m−2 h−1) and 35000 ppm salinity (oil rejection: 92.5% and permeate flux: 94nL m−2 h−1) at 0.2 MPa trans-membrane pressure.

Preparation and characterization of MWCNT-COOH/PVC ultrafiltration membranes to use in water treatment

Polyvinyl chloride (PVC) membranes containing pristine and modified multiwall carbon nanotube (MWCNT) were prepared and characterized. MWCNT was modified in order to achieve well-dispersion within the membranes. The results of FTIR analysis revealed that MWCNT was successfully carboxylated. The FESEM images indicated that the number of pores on the surface of membranes increased at the presence of pristine and modified MWCNT and the pore size distribution curves shifted towards smaller pores. The hydrophilicity, pure water flux, tensile strength and abrasion resistance of the membranes increased with increasing the content of MWCNT and COOH-MWCNT up to 0.3 wt. % and then decreased due to the agglomeration of nanotubes. Nevertheless, at the same content of nanotubes, COOH-MWCNT had more effect than MWCNT. The performance of the membranes was studied by filtration of humic acid (HA) solution and the results showed that HA rejection reached a peak of 96.88% for 0.3 wt. % PVC/MWCNT-COOH nanocomposite membrane. Finally, it was found that the antifouling properties of the membranes increased with increasing nanotube content, especially COOH-MWCNT.

Solid-Contact Ion-Selective Electrodes with Copper Hexacyanoferrate in the Transducer Layer

The possibility of using mixed Fe2+/Fe3+ copper hexacyanoferrate (CuHCF) as the material for the transducer layer of solid-contact ion-selective electrodes (SC-ISEs) with plasticized polyvinylchloride membranes is studied. The study is performed for K+-SC-ISEs and water-hardness SC-ISEs. It is shown that CuHCF combines the ion-exchange and redox properties and, hence, in principle, should be suitable for SC-ISEs. However, the reproducibility of SC-ISE potentials from one electrode to another and their stability in time are far below those of conventional ISEs with internal aqueous solution. The potentials of individual SC-ISEs can be brought closer to one another by their polarization using a potentiostat or by their short-circuiting to a saturated silver-chloride reference electrode.

Determination of paralytic shellfish toxins using potentiometric electronic tongue

Paralytic shellfish toxins (PSTs) are monitored in commercial bivalves in several countries in the world due to their toxicity to human consumers. The present work examines the application of an electronic tongue based on potentiometric chemical sensors to the quantification of PSTs in mussel extracts. The electronic tongue comprised six miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes. Calibration models were calculated by PLS regression using measurements in sixteen model mixed solutions containing four PSTs commonly found in bivalves from the Portuguese coast. Transfer of the calibration models to sample matrix was done by joint-PLS regression using measurements in five mussel extracts spiked with PST standards. Quantification of PSTs in extracts of naturally contaminated mussels, using the electronic tongue and updated calibration model, was in agreement with values of the chromatographic reference method. Those sensors alone or combined in an electronic tongue are useful tools for rapid screening of PST in bivalves.