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Vol 15, No 5-6 (2025)
Development of Membrane Technologies in Russia and the CIS Countries
Abstract
The review provides a brief overview of the latest achievements in the field of membranes and membrane technologies based on the reports presented at the last conference “Membranes-2025” by researchers from the CIS countries. The authors paid special attention to synthetic approaches that make it possible to obtain membranes of various types. New technologies and applications of ion exchange, gas separation and filtration membranes are also considered in detail.
Membranes and Membrane Technologies. 2025;15(5-6):285-298
285-298
Pervaporation Separation of Phenol from Water on Polyalkylmethylsiloxane Membranes: the Effect of the Length of the Side Substituent
Abstract
Phenol and its derivatives pose a significant environmental hazard even at low concentrations, making their efficient removal from industrial wastewater an urgent challenge. Pervaporation using selective membranes represents a promising energy-efficient approach for the concentration and recovery of phenol from aqueous streams. In this work, for the first time, a comprehensive investigation was carried out into the effect of alkyl side-chain length in poly(alkylmethylsiloxanes) on their affinity toward phenol and water, as well as on the transport properties of composite membranes in pervaporation. Hansen solubility parameter calculations revealed that the synthesized polymers are hydrophobic and exhibit a higher affinity for phenol than for water. However, with increasing alkyl chain length, the polymer–phenol interaction parameter decreases due to a reduced contribution of polar interactions. The highest phenol partition coefficients (up to 2.16 g/g) and the smallest polymer–phenol interaction radii were achieved for polymers bearing alkyl substituents with 6–7 carbon atoms. Membranes based on these polymers demonstrated the highest selectivity (~35) and separation factor (~11), performance metrics that are comparable to or exceed those of certain literature-reported analogues in terms of the selectivity–permeability ratio.
Membranes and Membrane Technologies. 2025;15(5-6):299-312
299-312
Investigation of the Water Vapor Influence on the CO2 Recovery from Flue Gases: Simulation under Various Membrane Module Operating Modes
Abstract
Despite the development of nuclear and alternative energy, thermal power plants that burn fossil fuels (coal, petroleum products or natural gas) will retain a significant share in the energy mix for a long time. In this regard, the reduction post-combustion CO2 emissions of organic fuels through its capture, utilization or storage. In this paper mathematical modeling of a CO2 recovery single-stage membrane process from flue gases of a thermal power plant was carried out taking into account the presence of water vapor on CO2 mass transfer and without taking into account their influence under different operating modes of the membrane module. Commercially available polymer gas separation membranes were selected for the simulation. The simulation results showed that taking into account the presence of water vapor makes it possible to reduce the required membrane area by 1.6 times. When comparing the operating modes of the membrane module it was shown that the cross-flow and countercurrent modes provide the same indicators of the required membrane area for CO2 recovery < 80%, while the co-current mode becomes less advantageous for CO2 recovery > 60%. Thus for low values CO2 recovery the choice of mode is not critical and for high values the counter-current has a slight advantage over the cross-flow mode.
Membranes and Membrane Technologies. 2025;15(5-6):313–323
313–323
Dehydrogenation of Hydrocarbons in Catalytic Membrane Reactors with Selective Hydrogen Extraction on Palladium-Containing and PNBI Membranes
Abstract
The paper considers the features of the processes of dehydrogenation of aliphatic and alkylaromatic hydrocarbons in a catalytic membrane reactor, in which, in addition to the stage of chemical transformation of reagents into reaction products, there is a stage of separation of the obtained products on a hydrogen-selective membrane on the catalyst. For the separation stage, in the first case, a dense membrane made of a palladium-ruthenium alloy twisted into an elastic spring was used, which was placed directly in the hot zone of the reactor (600°C). In the second case, a sequential gas separation module with a non-porous polymer film membrane of the polynaphthoylene benzimidazole (PNBI)-σ type was used, operating at a reduced temperature (250°C).
Membranes and Membrane Technologies. 2025;15(5-6):324-333
324-333
Modeling of the Membrane Gas Separation Process of CO2 Decomposition Products with the Production of CO and O2 Concentrates
Abstract
Carbonylation and oxidative carbonylation processes require the production of a concentrate of carbon monoxide or its mixture with oxygen. Such concentrates can be produced by plasma-chemical decomposition of CO2 into CO and O2. Given the low conversion of such processes, there is a need to develop separation schemes for the 73% mol. CO2/18% mol. CO/9% mol. O2 mixture to produce concentrates that are practical to use. This article proposes a conceptual scheme for separating CO2 decomposition products using membrane gas separation technology with polysulfone hollow fiber gas separation membranes (PSF). For the first time, data on the transfer of CO, CO2, and O2 through PSF membranes in a ternary mixture were obtained for the simulation. Calculations show that using PSF membranes with a total area of 5.28 m2 when processing 1 m3 (STP)/h of the CO2/CO/O2 mixture, 93.9% CO2 with a concentration of 93.6 % mol. and extract 68.5% CO with a concentration of 85% mol.
Membranes and Membrane Technologies. 2025;15(5-6):334-346
334-346
The Influence of the Molecular Weight of Sodium Polystyrene Sulfonate on the Mobility of Macromolecules in Aqueous Solution by NMR
Abstract
Diffusion processes in aqueous solutions of sodium polystyrene sulfonate with different molecular weights were studied using pulsed field gradient NMR. It was shown that Na⁺ cations in these polymers are partially replaced by ammonium ions NH₄⁺. A lognormal distribution of diffusion coefficients was introduced to interpret the experimental dependences of the spin echo signal amplitudes of the polymer matrix protons on the magnetic field gradient. It is related to the polymer molecular weight distribution. It was shown that, at the same polymer concentration, with increasing molecular weight, the average values of the diffusion coefficients decrease, and their distributions broaden. In the concentration range from 20 to 65 water molecules per sulfo group, the distribution width is independent of concentration, indicating the absence of macromolecular associates. With a further increase in the polymer molecule concentration, the distribution width of the diffusion coefficients increases, indicating the formation of associates.
Membranes and Membrane Technologies. 2025;15(5-6):347-357
347-357
Water Vapor Transport in Poly(2,6-Dimethyl-1,4-Phenylene Oxide)
Abstract
Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based membranes have been widely used in industry to separate various gas mixtures. Although there is a lot of data on the gas permeability of PPO in the literature, the water vapor permeability data of PPO is largely lacking. In this paper, the water vapor transport in amorphous PPO at 35 and 50°C with the water vapor activity from 0.2 to 0.8 was investigated. For this purpose, a laboratory sample of amorphous PPO-based composite membrane was prepared. As a result, the dependences of the water vapor permeability coefficient on vapor activity were obtained. Both dependences (for 35 and 50 °C) illustrated almost the same level of permeability and a tendency to decrease the water vapor permeability coefficient by about 17% with the vapor activity increase from 0 to 1. The obtained results can be used in the design and operation of membrane separation systems with PPO-based membranes in the presence of water vapor in the separated mixture.
Membranes and Membrane Technologies. 2025;15(5-6):358–367
358–367
Influence of Dispersed Carbon Particles in Solution on the Diffusion Mass Transfer through an Ion–Exchange Membranes
Abstract
The effect of activated carbon microparticles (ranging in size from 0.045 mm to 1 mm) dispersed in solution on the diffusion mass transfer through MK-40 and MA-41 ion-exchange membranes investigated experimentally. Various particle size fractions obtained through fractionation, as well as two types of activated carbon—birch-based and coconut-based—differing in their physicochemical and electrokinetic properties, were studied. It was shown that the introduction of carbon particles into the solution significantly increases the diffusion flux through the membranes. A relationship was established between the change in the diffusion permeability coefficient and the concentration of carbon particles in the solution, in the range from 0.1 to 2 g/L, enabling a quantitative assessment of each carbon type’s contribution to mass transfer through the membrane. In addition, it was found that the presence of phenol in the solution reduces the effectiveness of activated carbon, particularly for fine particle fractions. The results of this work may be useful for optimizing combined wastewater treatment methods involving sorption and electrodialysis processes.
Membranes and Membrane Technologies. 2025;15(5-6):368-376
368-376