Similar Journals
|
Membranes and Membrane Technologies
Number of Followers: 0  Subscription journalISSN (Print) 2517-7516 - ISSN (Online) 2517-7524 Published by Springer-Verlag  [2468 journals]
|
- Perfluorosulfonic Acid Polymer Membranes: Microstructure and Basic
Functional Properties-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The progress of modern technologies and the requirements imposed on the production ecology demand the development of new ion-exchange membrane polymer materials with a set of desired properties. These materials are used in liquid and gas separation and purification systems, chemical and electrochemical syntheses, and alternative energetics. Membrane materials based on perfluorosulfonic acid polymers (PFSA) possess a set of characteristics necessary for their practical application: high ionic conductivity and selectivity and good chemical stability, strength, and elasticity. This review addresses the microstructure of PFSA membranes and its change induced by water and solvent uptake and discusses the features of ion and gas transport, mechanical properties, and the dependence of a number of parameters on polymer chain length and ionic form.
PubDate: 2023-12-01
-
- Effect of the Approach to Membrane Gas Transport Characteristics
Determination on Gas Separation Process Simulation Results-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this work, the dependence of the output characteristics of the gas separation membrane process determined during the simulation on the gas transport characteristics of the membrane as parameters of the membrane module model has been studied. The study has been performed using the example of a laboratory sample containing hollow fibers from polyphenylene oxide. As a result of this comprehensive study, including theoretical and experimental approaches, it has been determined that when using the gas transport characteristics obtained for pure gases for process simulation, the error expressed in the achievable concentration of the target component in the product stream is from 1.5 to 8.8% in comparison with the experimentally obtained values for the module of the same geometry and the same membrane area. This discrepancy can lead both to the setting of unattainable targets when creating a technological line and to an incorrect technical and economic assessment of the process. Thus, when designing technological lines using mathematical modeling tools, one should rely on the gas transport characteristics of a material and/or product obtained for components of real or simulating real gas mixtures.
PubDate: 2023-12-01
-
- Kinetic Transport Coefficients through a Bilayer Ion Exchange Membrane
during Electrodiffusion-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Analytical expressions for the specific coefficients of electrical conductivity and electrodiffusion of a bilayer ion exchange membrane have been obtained in terms of thermodynamics of irreversible processes and the homogeneous model of a fine-pore membrane. The influence of the physicochemical parameters of the modifying layer and the electrolyte concentration on the obtained values of the coefficients at fixed physicochemical characteristics of the substrate has been explored using mathematical modeling. It has been shown that the conductivity and electrodiffusion of the modified membrane increase with increasing the space charge density of the modifying layer when the signs of the space charges of the membrane layers are identical and decrease when they differ or the thickness of the modifying layer increases. With increasing electrolyte concentration, these characteristics of the modified membrane increase regardless of the sign of charges of the membrane layers. The obtained analytical expressions can be used in modeling electromembrane processes and predicting the characteristics of new surface-modified ion exchange membranes.
PubDate: 2023-12-01
-
- Kinetic Analysis of Dry Reforming of Methane on Traditional and Membrane
Catalysts-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The article presents an analysis of the kinetic data on dry reforming of methane (DRM) in reactors with traditional (TC) and membrane catalysts (MC). The kinetic experiment in reactors with the TC and MC is performed in the temperature range of 820–900°С at CH4 : CO2 = 1 : 1. The experiment reveals intensification of the reaction of methane cracking; its rate constant increases by an order of magnitude. This difference in the DRM data obtained for the studied catalysts is explained by the fact in the case of the MC mass transfer is intensified due to the thermal slip phenomenon. A mathematical description corresponding to the kinetic scheme of the DRM process is proposed, and the rate constants of direct and reverse reactions in both reactors are determined. The DRM process carried out on the TC yields water vapor, while in the case of the MC syngas is produced. On the TC the DRM process is accompanied by the accumulation of carbon deposits (CDs), while on the MC this accumulation is absent. On the TC the DRM process is characterized by three main reactions (methane cracking, gasification of CDs with carbon dioxide and/or water vapor, and reverse water gas shift) which are assumed to be reversible under the experimental conditions. It is found that the gasification of CDs on the TC occurs in the reverse reaction of methane cracking; on the MC, in the reactions of CDs gasification with water vapor (mostly) and carbon dioxide. In the case of the MC, the process is characterized by the irreversible reactions of methane cracking and CDs gasification with water vapor and carbon dioxide. The reverse water gas shift reaction on the MC remains reversible, and its rate constants of direct and reverse reactions are an order of magnitude lower than similar rate constants on the TC.
PubDate: 2023-12-01
-
- Oil Deasphalting Using Ultrafiltration PAN Membranes
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: With the development of oil fields, the proportion of the highest-molecular-weight components, asphaltenes, increases in the composition of the extracted raw materials. The propensity of asphaltenes to aggregate causes a number of problems, which makes the task of oil deasphalting relevant. In this work, studies on separation of the asphaltene fraction from oil using PAN membranes are carried out. To decrease the pore size of membranes obtained by a phase inversion method, an additional component, acetone, is introduced into the casting solution. The permeability of the resulting membranes for water is 37.6 ± 1.7 L m−2 h−1 atm−1 and for toluene, 25.3 ± 1.8 L m−2 h−1 atm−1, and the pore size is 4.6 ± 0.5 nm. When filtering solutions of oil diluted with toluene (1 g/L), the retention of the membranes for asphaltenes is 73 ± 4%, while it exceeds 95% when the oil content in the solution is over 10 g/L. The parameters of membrane fouling during filtration of solutions of oil in toluene are studied. It is noted that, upon moving from toluene to solutions of oil, the permeability of the membranes decreases tenfold. At the same time, the decrease in permeability is reversible, and when the solution of oil is replaced by a pure solvent, the membrane restores up to 99% of its initial permeability.
PubDate: 2023-12-01
-
- Trifluoroethyl Acrylate-Substituted Polymethylsiloxane—a Promising
Membrane Material for Separating an ABE Fermentation Mixture-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: This work is aimed at obtaining a membrane material that is resistant to the formation of a precipitate on the surface upon contact with an ABE fermentation mixture and possesses a good separating ability during the pervaporation isolation of n-butanol from a water–alcohol mixture. In this regard, this work for the first time proposes creating pervaporation membranes based on polymethyltrifluoroethylacrylatesiloxane (F3-Acr) as well as a copolymer of polydecylmethylsiloxane and polymethyltrifluoroethylacrylatesiloxane (C10–F3-Acr). The structure and sorption properties of the developed membrane materials for n-butanol, ethanol, and acetone are studied in comparison with polydecylmethylsiloxane (C10). It should be noted that the highest sorption of n-butanol is characteristic for C10–F3-Acr (0.46 g/g). The change in the surface properties is assessed by the value of the contact angle and elemental composition of the surface before and after exposure for 1 month in a fermentation medium. The transport and separation properties of the synthesized membrane materials are studied in the vacuum pervaporation mode during the separation of a model ABE fermentation mixture. It is shown that introducing a fluorine-containing substituent into the side chain of polysiloxane makes it possible to increase the hydrophilicity of the polymer: the water flow for F3-Acr is 0.7 × 10−6 kg m m−2 h−1, which is almost threefold higher when compared to C10. A positive effect of the combination of C10 and F3-Acr groups in polysiloxane is worth noting. Thus, with an increase in the total flow by 60% when compared to a C10 membrane, the values of the separation factor for n-butanol, acetone, and ethanol are 40.5, 32.7, and 4.3 and increase by 6, 15, and 12%, respectively, when compared to a C10 membrane. For a C10–F3-Acr membrane, the pervaporation separation indices for n-butanol, acetone, and ethanol are 136, 109, and 11, respectively. Therefore, this membrane is twice as efficient as C10. Taking into account the absence of detectable contamination of the surface of the membrane material with fermentation products, one can note a high potential of a C10–F3-Acr membrane for the task of isolating alcohols from an ABE fermentation mixture.
PubDate: 2023-12-01
-
- Simulation of Impurity Absorption from Laminar Flow in a System of Hollow
Fiber Membranes-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The external steady flow of a viscous incompressible fluid and the convective-diffusion mass transfer of a solute in an ordered system of parallel hollow fiber membranes located perpendicular to the flow have been calculated in the ranges of Reynolds numbers \(\operatorname{Re} \) = 0.01–100 and Schmidt numbers \({\text{Sc}}\) = 1–1000. The Navier–Stokes equations and the convective diffusion equation have been solved using computational fluid dynamics methods with the no-slip boundary condition and the condition of a constant solute concentration on the outer surface of the streamlined fiber. Calculations have been performed for one row of fibers and for a system consisting of four and sixteen rows of fibers. The output concentrations and impurity absorption coefficients by the fiber \(\eta \) have been calculated depending on the packing density of the fibers \(\alpha \) and numbers \(\operatorname{Re} \) and \({\text{Sc}}\) . The studies have shown that the absorption coefficient \(\eta \) by the fiber in an isolated row of fibers can be used to calculate the absorption efficiency of a thick fibrous bed.
PubDate: 2023-12-01
-
- Gas Transport Properties of Vinylidene Fluoride-Tetrafluoroethylene
Copolymers-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Effect of the content of tetrafluoroethylene groups on the gas transport properties of vinylidene fluoride-tetrafluoroethylene copolymers has been studied. The experimental values of permeability coefficients P and diffusion coefficients D for gases H2, He, N2, O2, and CO2 as well as lower hydrocarbons CH4, C2H4, and C2H6 are measured, and their solubility coefficients S are calculated. It is shown that the values of the solubility coefficients of СО2 and С2Н4 deviate from the direct correlation dependence of lоg S on the Lennard-Jones potential, and this effect is explained in terms of facilitated transport models. It is demonstrated that an increase in the content of TFE groups leads to a significant rise in the permeability coefficients of the studied penetrants mainly due to an increase in their diffusion coefficients. For example, the permeability coefficient of helium and hydrogen increases by almost 2.5 times, carbon dioxide by 3 times, argon, oxygen, methane and ethylene by 3.5 times, and nitrogen and ethane by 4.4 times, respectively. These gas separation parameters in combination with good film-forming properties and commercial availability make it possible to consider the studied VDF-TFE copolymers to be promising materials for the fabrication of composite gas separation membranes.
PubDate: 2023-12-01
-
- Effect of the Nature of Counterion on Properties of Perfluorosulfonic Acid
Membranes with Long and Short Side Chains-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The paper presents the results of a study of water uptake, ionic conductivity, and Donnan potential in systems with perfluorosulfonic acid membranes in the H+, Li+, Na+, and K+ ionic forms and solutions of inorganic electrolytes. The properties of commercial membranes Aquivion E87-05S and Nafion 212, as well as membranes obtained from dispersions of Nafion 212 in solvents of various nature (N,N-dimethylformamide, 1-methyl-2-pyrrolidone, mixtures of isopropyl alcohol with water in a volume ratio of 80–20) have been studied. The effect of the number of functional groups, the length of the side chain of polymer macromolecules, and the morphology of the polymer in membranes on their equilibrium and transport properties depending on the nature of the counterion has been determined. The effect of relaxation and electrophoretic factors on the transfer of alkali metal ions through the system of pores and channels of perfluorosulfonic acid membranes is discussed. The slope of the concentration dependences of the Donnan potential for all highly hydrated membranes in the H+ form has been found to be close to the Nernstian one, while the selectivity to alkali metal ions increases for membranes with the highest ion exchange capacity or the lowest amount of sorbed water and diffusion permeability due to the exclusion of co-ions from the membrane phase.
PubDate: 2023-10-01
-
- Evaluation of the Effect of Electroosmosis on the Efficiency of
Electrobaromembrane Separation with Track-Etched Membranes-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The results of a theoretical analysis of the influence of the electroosmotic flow on the electromigration and convective transport of competing ions separated by the electrobaromembrane process are presented. Separated ions of the same charge sign move in an electric field through the pores of a track-etched membrane to the corresponding electrode, while a commensurate convective counterflow being created by the pressure drop across the membrane. A simplified model based on the convective electrodiffusion equation and the Hagen–Poiseuille equation allows the analysis of experimental data using only the effective transport numbers of ions in the membrane as fitting parameters. Using a 2D mathematical model described by the system of Nernst–Planck, Navier–Stokes, and Poisson equations, it is shown that the electroosmotic flow can cause the effective transport numbers of competing ions to exceed their values in solution, even if these ions are coions for the membrane.
PubDate: 2023-10-01
-
- Investigation of Low-Temperature Hydrogen Permeability of Surface Modified
Pd–Cu Membranes-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Pd60%Cu40% alloy membranes are modified with nanostructured coatings to intensify the low-temperature (25–100°С) transport of hydrogen. Classical palladium black and filamentous particles are deposited as surface modifiers by electrodeposition. The experimental data confirm that the deposition of the modifying layer on both surfaces of the Pd60%Cu40% alloy membranes can considerably reduce surface limitations for the process of hydrogen transfer. In the low-temperature hydrogen transport processes, the developed membranes demonstrate high and stable fluxes up to 0.36 mmol s–1 m–2 and high hydrogen permeability up to 1.33 × 10–9 mol s–1 m–2 Pa–0.5. For the Pd60%Cu40% alloy membranes modified with nanofilaments hydrogen permeability is up to 1.3 times higher compared with the membranes modified with classical black and up to 3.9 times compared with the uncoated membranes. The Pd60%Cu40% alloy membranes also exhibit a high level of H2/N2 selectivity, up to 3552. The strategy of surface modification of palladium-based membranes can shed new light on the development and manufacture of high-performance and selective membranes for ultrapure hydrogen production units.
PubDate: 2023-10-01
-
- Transference Numbers of Counterions in the Cell Model of a Charged
Membrane-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: The paper suggests exact formulae for calculating the electromigration, diffusion, and convective transference numbers of counterions in the cell model of a charged membrane depending on the physicochemical parameters and equilibrium concentration of the electrolyte. The cell model was previously developed to calculate all the kinetic coefficients of the Onsager matrix, and the asymmetry of the cross coefficients was established. A limiting case of an ideally selective membrane is studied in detail, for which approximate formulae for transference numbers are obtained. The obtained dependences are illustrated by graphs by way of example of an MK-40 cation-exchange membrane after conditioning at room temperature. The proposed calculation procedure for transference numbers is applicable to any single-layer membranes in solutions of a binary electrolyte.
PubDate: 2023-10-01
-
- Neutralization Dialysis of Phenylalanine and Mineral Salt Mixed Solution:
Effect of Concentration and Flow Rate of Acid and Alkali Solutions-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Amino acids that are ampholytes can be effectively separated and purified by the method of neutralization dialysis (ND), whose advantage is the ability to control the pH value of the solution without adding reagents. An important task is to optimize the parameters of the ND process to ensure minimal losses of amino acids during their isolation from mixed solutions. An experimental study of the process of demineralization of the phenylalanine and sodium chloride equimolar mixture by the ND method is carried out. It is established that varying the concentration and flow rate of acid and alkali solutions in the corresponding compartments of the dialysis cell allows for regulating the pH value of the solution being desalted and controlling the amount of amino acid losses. Halving the acid concentration (from 0.10 to 0.05 M) allowes reducing the losses of phenylalanine from 18.3 to 16.4%, and using a lower solution flow rate in the acid compartment (0.75 instead of 1.50 cm s–1) makes it possible to reduce these losses to 14.2%. At the same time, in all experiments, the electrical conductivity of the solution being desalted decreases by 90%, which suggests a high demineralization rate and the effectiveness of the method used to isolate phenylalanine from the mixed solution.
PubDate: 2023-10-01
-
- Deoxygenation of CO2 Absorbent Based on Monoethanolamine in Gas–Liquid
Membrane Contactors Using Composite Membranes-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: This work is devoted to the removal of dissolved oxygen from a model absorbent based on monoethanolamine (MEA) to prevent its oxidative degradation during the absorption purification of flue gases from carbon dioxide. Composite membranes based on porous ceramic and polymeric supports with a thin selective layer of poly[1-(trimethylsilyl)-1-propyne] or its blend with polyvinyltrimethylsilane are developed, and gas-liquid membrane contactors are created on their basis. It is shown that the use of these contractors in the vacuum mode allows the removal of up to 60% of dissolved oxygen from the model sorbent.
PubDate: 2023-10-01
-
- Study of the Production of Sodium Hydroxide by Bipolar Electrodialysis
from Sodium Carbonate Solution-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: In this work, the production of sodium hydroxide by the method of bipolar electrodialysis from a solution of sodium carbonate using bipolar membranes MB-3 has been studied. For research, a laboratory electrodialyzer-synthesizer with a three-chamber unit cell has been used. The membrane package of the electrodialyzer has contained five elementary cells, the active area of each membrane being 1 dm2. To compare the obtained mass transfer characteristics, the process of preparation of sodium hydroxide from sodium sulfate has been additionally studied. It has been shown that the use of sodium carbonate as the initial solution makes it possible to increase the concentration of the resulting alkali from 0.92 to 1.7 M under comparable process conditions compared to the preparation of sodium hydroxide from a sodium sulfate solution. When sodium carbonate is used, the alkali current efficiency is more than 70% in all experiments, while when alkali is obtained from a sodium sulfate solution, the current efficiency drops sharply to 0.4–0.5% when the concentration exceeds 0.8 M NaOH. The energy consumption for the transfer of one kg of alkali is in the range of 2.8–13.9 kWh/kg at operating current densities of 1–3 A/dm2.
PubDate: 2023-10-01
-
- Experimental Determination of the Gas Transport Characteristics of
Polysulfone and Poly(phenylene oxide) Hollow Fiber Membranes in Relation
to Noble Gases-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Commercially available hollow fiber membranes made of two polymers, namely, polysulfone and poly(phenylene oxide), are studied experimentally. The main task of this study is to estimate the gas transport characteristics of these membranes in relation to air components and noble gases. Therefore, the values of permeability of the membranes for nitrogen, oxygen, helium, argon, xenon and krypton are measured. Particular attention is paid to the xenon-containing air mixture, since the capture of medical xenon is an urgent chemical and technological problem due to a high cost of the process of obtaining this gas. The values of permeability of the two membranes for individual gases are determined, and the values of ideal selectivity are calculated. For example, the values of membrane permeability for argon, krypton, and xenon are 20.8, 8.4, and 6.8 GPU for the polysulfone membrane and 19.5, 6.2, and 4.8 GPU for the poly(phenylene oxide) membrane, respectively. It is found that the xenon permeability of these membranes in the case of separation of the gas mixture composed of nitrogen, oxygen, and xenon is 5.9 and 4.1 GPU for polysulfone and poly(phenylene oxide). It is also shown that the performance of membrane modules based on polysulfone and poly(phenylene oxide) depends on the total membrane area.
PubDate: 2023-10-01
-
- Low-Temperature Ion-Plasma Pretreatment of Fibrous Systems during
Preparation of Composite Heterogeneous Membranes-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: An original method of obtaining cation exchange composite heterogeneous membranes involving the low-temperature ion-plasma pretreatment of fibrous systems is proposed. The membranes are obtained by the polycondensation filling of polymer composites via the synthesis and hardening of a strongly acidic sulfo cation exchanger on the surface and in the structure of a novolac phenol-formaldehyde fibrous system. The effect of low-temperature ion-plasma pretreatment on a change in the hydrophilicity, capillarity, and structure of heterogeneous cation exchange composite materials Polykon is investigated.
PubDate: 2023-08-01
DOI: 10.1134/S2517751623040066
-
- State-of-the-Art of Forward Osmosis Technology: Prospects and Limitations
-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Forward osmosis is considered as an emerging technology that can compete with existing methods of desalination, purification, and concentration of natural and wastewater on the global water market. This review presents possible applications of forward osmosis, technological schemes, and the most striking case studies. The issues of forward osmosis membranes development and improvement, composition and regeneration of draw solutions, membrane fouling are considered. Special attention is paid to the problems arising during forward osmosis operation as well as to energy and economic assessment of new technology. Conclusions are drawn about the status of the commercial implementation of forward osmosis and the main barriers that stand in the way of its development.
PubDate: 2023-08-01
DOI: 10.1134/S2517751623040029
-
- Fabrication of Ultrafiltration Membranes from PAN Composites and
Hydrophilic Particles for Isolation of Heavy Oil Components-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Membranes have been fabricated from polyacrylonitrile (PAN) doped with graphene oxide (GO) particles, PAN pyrolyzed by IR irradiation (IR-PAN-a), and nanodiamonds (ND). The pore structure of the resulting membranes has been studied. It has been shown that the addition of carbonaceous components slightly reduces the average pore size of the membranes from 17 to 12–15 nm, thereby leading to a decrease in the water permeability of membranes from 158 to 80.9–119.9 kg/(m2 h atm). Doping with particulate additives led to surface hydrophilization: the contact angle of water decreased from 65° to 48°–55°, facilitating the flow of crude oil solutions in toluene by a factor of 2–3 compared to the PAN membrane. However, the addition of GO or IR-PAN-a promoted a significant increase in irreversible membrane fouling. On the other hand, the addition of nanodiamonds not only reduced the overall fouling of the membrane and increased the permeability of the feed mixture from 4.93 to 8.47 kg/(m2 h atm), but also made it possible to recover more than 96% of the pure toluene flux. The rejection ratio of ND-doped membranes during the filtration of 10 g/L oil solutions in toluene was 85–89%.
PubDate: 2023-08-01
DOI: 10.1134/S2517751623040078
-
- Electrodialysis Separation and Selective Concentration of Sulfuric Acid
and Nickel Sulfate Using Membranes Modified with Polyaniline-
Free pre-print version: Loading...Rate this result: What is this?Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Surface-modified cation exchange materials are obtained based on industrial MK-40 heterogeneous and MF-4SK homogeneous cation-exchange membranes by in situ oxidative polymerization of aniline under electrodialysis conditions. The conduction and diffusion characteristics of the initial and modified membranes in solutions of sulfuric acid and nickel sulfate are studied. It is shown that the modification of the membranes with polyaniline leads to a decrease in their electrical conductivity and diffusion permeability without sacrificing high selectivity. The diffusion permeability of the cation-exchange membranes is higher in solutions of nickel sulfate in comparison with solutions of sulfuric acid, while an inverse dependence is found for anion-exchange membranes. The competitive transport of sulfuric acid and nickel sulfate during electrodialysis separation and concentration of their mixture using initial commercial and modified cation-exchange membranes paired with an MA-41 anion-exchange membrane is studied. It is shown that applying a layer of polyaniline with positively charged groups onto one of the surfaces of MK-40 or MF-4SK cation-exchange membranes leads to a decrease in the transport of a doubly charged nickel cation both in the separation and concentration modes over the entire range of current densities. The highest repulsion effect is observed in the case of the use of homogeneous modified membranes, where the selective permeability coefficient P(H2SO4/NiSO4) increases from 0.7–1.7 up to 32.5–19.7 depending on the current density. It is found that the use of surface-modified with polyaniline cation-exchange membranes makes it possible to concentrate a solution containing 0.1 mol-equiv/L (4.9 g/L) H2SO4 and 0.1 mol-equiv/L (7.7 g/L) NiSO4 with simultaneous separation to sulfuric acid with a concentration of about 2.4 mol-equiv/L (120 g/L) and a solution of nickel sulfate. Here, the concentration of nickel sulfate in the concentrate does not exceed 0.13 mol-equiv/L (10 g/L).
PubDate: 2023-08-01
DOI: 10.1134/S2517751623040030
-
