For the first time, this study reports the development and investigation of dual-function mixed matrix membranes (MMMs) based on poly(ether-block-amide) (PEBA) modified with the copper-based metal-organic framework HKUST-1, possessing advanced properties and designed for pervaporation (PV) and gas separation (GS). A systematic study of HKUST-1 incorporation (5-15 wt%) into PEBA revealed that optimal 10 wt% loading improved permeation flux and selectivity by 1.9- and 1.1-fold, respectively, for isopropanol/water (5/95 wt%) separation. The supported membrane showed a 10.5-fold increase in flux over dense PEBA. Furthermore, PV of isopropanol/phenol aqueous mixtures at elevated temperatures and GS tests confirmed sustained enhanced transport properties with higher permeability. Specifically, the CO2 and CH4 permeabilities increased by 24.4% and 165.3%, respectively, compared to the unmodified supported membrane. To elucidate the structure-property relationships, various techniques (Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron and atomic force microscopies, water contact angle, and swelling degree measurements) were employed. DFT calculations were performed to investigate non-covalent interactions in hypothetical molecular associates. The demonstrated efficiency in both PV and GS underscores the versatility of PEBA/HKUST-1 MMMs, positioning them as promising candidates for advanced membrane processes.

Today, reducing carbon footprints requires the development of technologies to utilize CO2, particularly by converting it into valuable chemical products. One approach is plasma-catalytic CO2 splitting into CO and O2. The task of separating such a ternary mixture is nontrivial and requires the development of an efficient method. In this paper, we have developed a comprehensive scheme for the separation of a CO2/CO/O2 mixture using membrane technology. The novelty of this work lies in the development of a complete scheme for separating the products of plasma-chemical decomposition of CO2 to produce a CO concentrate. The calculations utilized the principle of a reasonable balance between the recovery rate and the energy consumption of the separation process. This scheme allows production of a CO stream with a purity of 99%. To achieve this goal, we have proposed the sequential use of CO2-selective membranes based on polysiloxane with oligoethyleneoxide side groups (M-PEG), followed by polysulfone (PSF) hollow-fiber membranes to separate CO and O2. For these membranes, we measured the CO permeability for the first time and obtained the selectivity for CO2/CO and O2/CO. The potential of membrane separation was demonstrated through a three-stage process, which includes recycling of the CO removal stream and concentration after CO2 plasmolysis. This process was calculated to yield a highly pure CO stream containing 99 mol% with a recovery rate of 47.9–69.4%. The specific energy consumption for the separation process was 30.31–0.83 kWh per 1 m3 of feed mixture, and the required membrane area was between 0.1 m2 for M-PEG and 42.5–107 m2 for PSF, respectively.

Despite the development of nuclear and alternative energy, thermal power plants operating by burning fossil fuels (coal, petroleum products or natural gas) will retain a significant share in the energy balance for a long time. In this regard, it is of particular interest to reduce CO2 emissions from the combustion of organic fuels through its capture and subsequent use or burial. In our work, mathematical modeling of the two-stage process of membrane extraction of CO2 from the flue gases of a thermal power plant was carried out, taking into account the presence of water vapor and various operating modes of the membrane module. We used commercially available polymer membranes for gas separation in our simulations. The calculations showed: Taking into account the presence of water vapor makes it possible to reduce the required membrane area by 1.6 times; For the degree of CO2 extraction < 80% in one stage, cross-flow and counter-current modes provide equal indicators for the required membrane area, and the co-current mode turns out to be less advantageous already with a degree of CO2 extraction > 60%. In this regard, in the area of low CO2 extraction values at the first stage, any flow organization mode in the membrane module can be selected, and in the high area, a counter-current has a slight advantage over the cross-flow mode; An optimal combination of membrane areas in the first and second stages is shown to achieve the maximum CO2 concentration in the product stream; Polaris Gen-2 membranes provide the best performance after two-stage separation: the CO2 content in the product stream was > 85 mol% and > 90 mol% with a total recovery rate of 80 and 50%, respectively; PolyActive and PPO membranes provide equal indicators for the CO2 content in the product stream, but in the use of PolyActive, the required membrane area is 2.3 times less.

Gas transport properties of two sets of polynorbornenes bearing carbocyclic substituents of different nature (cyclohexyl, norbornyl, phenyl groups, and framed oligocyclic moieties) were systematically studied. The influence of side-chain carbocyclic substituents on gas permeability and separation selectivity for CO2-containing gas pairs and gaseous hydrocarbons was evaluated. It was found that the presence of carbocyclic moieties in side chains of polynorbornenes promotes the increase in gas permeability similarly to that of SiMe3 groups, with this effect being enhanced by the increase in the number of cycles in the substituents. As a result, P(CO2) of the metathesis polymer with pentacene-based substituents is equal to 1200 Barrer. Studied polynorbornenes with carbocyclic substituents displayed promising gas separation selectivities: CO2/N2 separation selectivity up to 41 (above the 2008 upper bound in the Robeson diagram) and solubility-controlled hydrocarbon separation selectivity up to 16 for the n-butane/methane gas pair. For the polymer with pentacene-based substituents, the separation of the mixture of hydrocarbons and aging were studied. The studies revealed that the mixed gas C4/C1 separation selectivity of this polymer reaches 4, and a two-time reduction of permeability occurs in 8.5 months. Therefore, the incorporation of carbocyclic groups in the side chains of polynorbornenes can be considered as an efficient strategy for the design of polymeric gas separation membrane materials.

Xenon is a high-cost precious inert gas having the great potential to use in clinical anesthesia. A promising way to reduce the cost of the medical procedure is recovery of Xe from the used anesthetic mixtures. Membrane gas separation can be prospective and effective technology for this purpose, however, the lack of data on xenon transport in polymeric membranes hinders exploitation and deployment in this area. This paper describes the study of temperature effect in the range 0-50 degrees C on Xe/O-2 selectivity of various membrane polymers and membranes. Theoretical estimation of xenon permeability at different temperatures was performed for PVTMS, PC, TMPC, TMHFPC, PTMSP, PDMS and polyarylate copolymer with PDMS (A-PDMS). Experimental data were obtained for industrial membrane MDK-1 (siloxane-based copolymer selective layer) and industrial PPO hollow fiber membrane (HF PPO). Theoretical and experimental results show that membrane polymers can be divided into two groups: (1) oxygen-selective PVTMS, TMHFPC, PC, TMPC, PPO, and (2) xenon-selective PDMS, A-PDMS, PTMSP, and MDK-1 membrane. Almost all considered polymers and membranes increase selectivity with temperature decrease. Minor selectivity changes among both groups demonstrate TMHFPC, while PVTMS, PC, TMPC, PPO, PDMS, A-PDMS, PTMSP and MDK-1 exhibit an increasing selectivity as the temperature decreases. HF PPO membrane provides the highest O-2/Xe selectivity and MDK-1 has as high Xe/O-2 selectivity as PDMS. The O-2/Xe selectivity of HF PPO rises from 8.5 to 15 and Xe/O-2 selectivity of MDK-1 improves from 3.0 to 4.7 while decreasing temperature from 50 to 0 degrees C, however, it leads to permeance decline of both O-2 and Xe in this case. Nevertheless, still high permeance of these membranes at 0 degrees C (216 GPU for Xe in MDK-1 and 47.4 GPU for O-2 in HF PPO) in combination with elevated selectivity represents attractive properties for the membrane separation system development. Modeling of a medical anesthetic O-2/Xe mixture (30/70 vol%) separation by one-, two-, and three stage membrane systems using HF PPO and MDK-1 membranes was performed. Single-stage separation with MDK-1 membrane is allowing for a maximum xenon purity of around 91 vol %. Single-stage separation with HF PPO demonstrates increasing the xenon recovery from 0.45 to 0.59 at a xenon purity of 99 vol% while lowering the temperature from 50 to 0 degrees C. For a two-stage HF PPO based membrane system the recovery of xenon increases by approximately 0.26 compared to single-stage separation at all temperatures. Introducing the supplement xenon-selective stage with MDK-1 membrane leads to additional increase xenon recovery by 0.11 reaching a value of 0.95 and 99 vol% of xenon purity at 0 degrees C. These separation characteristics exhibit corresponding values of sorption systems for xenon capture and recovery. Obtained results demonstrate potential of application gas separation systems combining membranes with xenon- and oxygen selective properties.

The goal of this work was to investigate the effect of non-solvent nature on the formation of porous membranes via non-solvent/thermally induced phase separation (N-TIPS). The hot solution of polypropylene (PP) in a mixture of dioctyl phthalate (DOP) and dibutyl phthalate (DBP) at 210 degrees C was placed as a thin film on a polyethylene terephthalate (PET) substrate, and then precipitated by immersion in the non-solvent (water, iso-propanol, 1-hexanol, or 1-decanol) at room temperature. It was found that the non-solvent nature greatly affected the morphology of the thin skin layer of the membrane facing the precipitation bath, which can be attributed to non-solvent induced phase separation (NIPS). The affinity between the polymeric solution and corresponding non-solvent was evaluated by using Hansen solubility parameters of components taken at room temperature and extrapolated to the temperature of 210 degrees C. An increase in the affinity between the non-solvent and the polymer transformed the surface layer structure from almost monolithic to cellular (with different pore sizes and porosity) and to spherulitic types. The non-solvent nature played a less pronounced role in the formation of the porous structure of the membrane bulk and the back side of the membrane (facing the PET substrate). Since the morphology of the rest of the membrane was correlated with thermophysical properties of non-solvents, it was concluded that the membrane formation took place due to temperature induced phase separation (TIPS). In the case of water, which has the highest cooling rate, the polypropylene crystallized by forming a "smectic" structure, while the standard alpha-lamellar structure was observed for other non-solvents. To gain insight into the TIPS process, a model of unsteady one-dimensional heat transfer was applied to simulate the change in the temperature profile of the hot, thin film of polymeric solution placed in the corresponding non-solvent. The resulting membranes were mainly in the microfiltration range with a mean through pore size of 0.05-0.61 mu m, and iso-propanol permeance of 2.1-8.4 m(3) m(-2)center dot h(-1)center dot bar(-1). The rejection of 500 nm polystyrene microspheres was in the range of 45-98 %. The tensile strength was in the range of 2.9-3.2 MPa, and elongation at break was 30-190 % with respect to the non-solvent used.

Carbon capture and storage is one of the potential options for reducing CO2 emissions from coal-fired power plants while preserving their operation. Mathematical modeling was carried out for a one-stage membrane process of carbon dioxide capture from the flue gases of coal-fired power plants using commercial gas separation membranes. Our calculations show that highly CO2-permeable membranes provide similar characteristics with respect to the separation process (e.g., a specific area of membrane and a specific level of electrical energy consumption) despite the significant variation in CO2/N2 and H2O/CO2 selectivity. Regarding the development of processes for the recovery of CO2 from flue gas using membrane technology, ensuring high CO2 permeance of a membrane is more important than ensuring high CO2/N2 selectivity. The presence of water vapor in flue gas provides a higher driving force of CO2 transfer through the membrane due to the dilution of CO2 in the permeate. A cross-flow membrane module operation provides better recovery of CO2 in the presence of water vapor than a counter-current operation.

This work is devoted to the evaluation of xenon permeability coefficients for a wide range of polymeric membrane materials, as well as the primary experimental verification of the calculation results for materials used in the production of gas separation membranes. The solution of the problem of O2/Xe mixture separation as a base for xenon-containing waste medical gas mixtures where it is possible to recover xenon for its reuse has been emphasized. The xenon permeability coefficients have been evaluated using a correlation approach that relates the molecular properties of a gas to gas permeability, and available literature data on the permeability of other gases. The results obtained make it possible to distinguish two main groups of membrane polymers in the Robeson diagram for O2/Xe gas pair: xenon-selective (polysiloxane-based rubbers and highly permeable functional polyacetylenes) and oxygen-selective (polyimides, PIMs, perfluorinated polymers). Industrial composite membrane MDK with a selective layer of silicone copolymer and laboratory composite membranes based on PSf and PVTMS have been experimentally investigated. The obtained data demonstrate satisfactory convergence of the experimental values with the estimated ones. Based on the results obtained, MDK membrane can be recommended as xenon-selective for xenon recovery (α(Xe/O2) = 3.1).

One of the promising technologies in demand is biomass processing to obtain various organic substances including energy carriers and valuable chemicals. Developing processes for the bioprocessing of lignin suggest the use of a synthetic biological system that allows the production of lower aliphatic alcohols through the stage of formation of carboxylic acids. Due to the production of alcohols in the form of dilute aqueous solutions, their recovery and concentration are extremely energy-consuming steps. In this paper, we consider the membrane vapor separation method as applied to aqueous solutions containing alcohols and organic acids. The transfer of vapors of water and С1–С4 alcohols through commercial pervaporation and gas separation membranes that have not been studied for this purpose, as well as through a laboratory membrane, has been studied. The highest separation performance of water–alcohol mixtures was demonstrated by the RomakonTM-PM 102 membrane, which was also investigated in the separation of mixtures with acetic acid. On the basis of the experimental data obtained, mathematical modeling of the process of ethanol recovery from the water/ethanol/acetic acid ternary mixture by the membrane vapor separation method was carried out.

A significant proportion of natural gas (NG) is produced in cold climates, where conditions are relevant to the formation of gas hydrates in raw gas stream. Methanol is often used as an effective inhibitor of hydrate formation. Further conditioning of NG includes dehydration, and the most common process of water vapor removal from NG is absorption. Absorption also provides removal of methanol vapors, which allows it reuse. The membrane method of natural gas dehydration is considered as a promising alternative; however, the study of methanol recovery by the membrane method, simultaneously to the dehydration of NG, has not been carried out previously. In addition, data on methanol vapor transfer in gas separation polymer membranes are almost absent in the literature. This paper evaluates the permeability coefficients of methanol vapors for several polymer materials, which are applied to the production of industrial membranes (PPO, PSf, CA). Mathematical modeling of the membrane process of NG dehydration with simultaneous recovery of methanol was performed. The dependencies of membrane area, methanol recovery and energy consumption for methane recycling and recompression on the process parameters are calculated. Obtained data show that the recovery of methanol during membrane dehydration of NG varies in the range 57–95%. The lowest values of membrane area and specific energy consumption were found for PPO based membrane.

This paper presents the results of a study of the gas transfer and selective properties of PMP hollow fibres (HFs) produced by melt spinning technology. The HFs are characterized by WAXD, SEM and DSC methods. Transport and separation properties have been determined in relation to N2, CO2, methane, butane and different mixtures in the temperature range from -10 to 80 degrees C. It has been shown that the permeance of methane in mixture with N2 and CO2 is similar to the pure methane transport, whereas the presence of butane changes PMP properties and influence transport of methane. An increase in the activity of butane in a mixture with methane led to a significant increase in the permeation flux of both butane and methane through the walls of the HFs. It was shown that PMP changes properties from methane-selective at low butane activities to butane -selective at higher butane activities. The changing of butane and methane permeance in a mixture was found well described by an exponential dependence on the activity of butane. The values of permeance parameters were determined by different methods and found to be in good agreement between each other. Discovered effect for methane/butane mixture transfer in PMP HFs allows to perform the simulation of hydrocarbons separation taking into account changing of membrane properties and discovering of promising areas and conditions of practical application for the new PMP HFs.

The recovery of lower aliphatic alcohols from dilute aqueous solutions presents a demanding task for solving a number of problems including the generation of energy from renewable raw materials. One of the promising processes for concentrating alcohols is the membrane vapor separation method using water-selective membranes. In this work, the transport and separation characteristics of the industrial nanofiltration membrane NaRM, manufactured by JSC RM Nanotech, in the separation of vapor mixtures of water and aliphatic C1–C4 alcohols at a temperature of 60°C have been studied. It has been shown that the transport and separation characteristics of the membrane used in the vapor phase process undergo a significant change, which is associated with the gradual removal of glycerol used as a preserving agent. The obtained stable values demonstrate high water vapor permeability, at the level of commercial pervaporation membranes, and the water/alcohol selectivity in the range of 25–45. The results of the study can help to expand the scope of practical application of the domestic membrane in the processes of recovery of alcohols from dilute aqueous solutions using the membrane vapor separation method.

The rapid advancement of membrane gas separation processes has spurred the development of new and more efficient membrane materials, including polymers of intrinsic microporosity. The full exploitation of such materials requires thorough understanding of their transport properties, which in turn necessitates the use of powerful and reliable characterization methods. Most methods focus on the permeability, diffusivity and solubility of single gases or only the permeability of mixed gases, while studies reporting the diffusion and solubility of gas mixtures are extremely rare. In this paper we report the use of a mass-spectrometric residual gas analyser to follow the transient phase of mixed gas transport through a benzotriptycene-based ultrapermeable polymer of intrinsic microporosity (PIM-DTFM-BTrip) and a polydimethylsiloxane (PDMS) membrane for comparison, via the continuous online analysis of the permeate. Computational analysis of the entire permeation curve allows the calculation of the mixed gas diffusion coefficients for all individual gases present in the mixture and the identification of non-Fickian diffusion or other anomalous behaviour. The mixed gas transport parameters were analysed by three different approaches (integral, differential and pulse signal), and compared with the results of the ‘classical’ time lag method for single gases. PDMS shows very similar results in all cases, while the transport in the PIM gives different results depending on the specific method and instrument used. This comparative study provides deep insight into the strengths and limitations of the different instruments and data elaboration methods to characterize the transport in rubbery and high free volume glassy membranes with fundamentally different properties and will be of help in the development of novel membrane materials.

The permeability of n -butane and methane as well as their mixture through a PDecMS/MFFK composite membrane at reduced temperatures up to 0°C is for the first time studied in this work. According to the data of SEM, the thickness of the selective layer of PDecMS is 5 μm. It is shown that both the permeability coefficient of butane and ideal butane/methane selectivity α_C_4H_10/ . -0emCH_4 increase as the temperature decreases from 60 down to 0°C. Thus, the permeability coefficient of butane is 11 400 Barrer at 0°C. It is important to emphasize that the ideal butane/methane selectivity of PDecMS/MFFK of 60 at 0°C is twofold higher than similar values for MDK and PDMS membranes (27 and 32, respectively). This is first of all associated with the difference in the values of the sorption selectivity α S of these polymers. Thus, the values of α _C_4H_10/ . -0emCH_4^S for PDecMS and PDMS at 0°C estimated based on the enthalpy of sorption are 170 and 95, respectively. In addition, the difference in the activation energies of diffusion of methane in PDecMS, PDMS, and MDK provides a sharper increase in the butane/methane permselectivity for PDecMS when compared to PDMS and MDK in the case of decreasing the measurement temperature. In the case of a C 4 H 10 (35 vol

The paper presents the results of applying the membrane gas separation technique to the recovery of CO2 and its subsequent utilization by converting into ammonium carbamate. One-sided surface modification of homogeneous polyvinyltrimethylsilane (PVTMS) films by treating in low-temperature air plasma for 30 and 60 s has been carried out. The transport and gas separation properties of the modified samples has been investigated, and values for the permeability and diffusion coefficients of CO2, N-2, and CH4 have been experimentally obtained. On the basis of the experimental data, the effective coefficients of gas solubility in the modified film have been determined. It has been found that by modification within 30 s, the CO2/N-2 and CO2/CH4 separation factors are increased by two and three times, respectively, relative to the initial values. To assess the possibility of using the new membranes, mathematical modeling of a single-step membrane process for the separation of biogas components under steady-state and non-steady-state has been carried out. It has been shown that the proposed membrane modification method makes it possible to significantly increase the performance of the membrane unit: for example, the recovery of CH4 under steady-state conditions is increased from 70 to 86%, and the CO2 content in the permeate increases from 68 to 82 mol %. The reaction of ammonium carbamate production from CO2 and ammonia in recycled vegetable oil as a solvent has been successfully conducted using the calculated characteristics of the membrane module based on modified PVTMS.

The features of the butane transfer through homogeneous membranes 40–50 μm thick based on poly(4-methyl-1-pentene) (PMP) of various crystallinity degrees have been investigated in the temperature range from 10 to 80°C. It has been shown that in this temperature range, including Tg of the polymer, for continuous PMP membranes obtained by the melt technology there is a significant influence of butane activity, which was previously described in the literature for composite membranes based on PMP with thin selective layers formed from solutions. It has been noted that the degree of crystallinity of PMP has a significant effect on the permeability. Based on the experimental data, the temperature parameters have been calculated taking into account the exponential form of the dependence of permeability on the butane activity. Temperature dependences have been obtained in the absence of the influence of butane on the polymer, which have a nearly linear form in the Arrhenius coordinates, while practically coinciding for samples with different degrees of crystallinity.

Designing hollow fiber (HF) membrane modules occupies one of the key positions in the development of efficient membrane processes for various purposes. In developing HF membrane modules, it is very important to have a uniform HF distribution and flow mixing in the shell side to significantly improve mass transfer and efficiency. This work suggests the application of different textile 3D HF structures (braided hoses and woven tape fabrics). The 3D structures consist of melt-spun, dense HFs based on poly(4-methyl-1-pentene) (PMP). Since the textile processing of HFs can damage the wall of the fiber or close the fiber bore, the membrane properties of the obtained structures are tested with a CO2/CH4 mixture in the temperature range of 0 to 40 °C. It is shown that HFs within the textile structure keep the same transport and separation characteristics compared to initial HFs. The mechanical properties of the PMP-based HFs allow their use in typical textile processes for the production of various membrane structures, even at a larger scale. PMP-based membranes can find application in separation processes, where other polymeric membranes are not stable. For example, they can be used for the separation of hydrocarbons or gas mixtures with volatile organic compounds.