RU2714644C1 - Composite asymmetric polymer pervaporation membrane - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the chemistry of high-molecular compounds. Membrane consists of a porous working selective diffusion layer formed from a polyimide with a link formula:

m:n = 0–2, or a salt form thereof with triethylammonium ions, alkali and/or alkali-earth metals, or a cross-linked aromatic diamine of a nanoporous form underlayer and microporous substrate, together comprising an ultrafiltration membrane substrate made from the same polyimide, or other polymer used to make ultrafiltration membranes, thickness of the working layer is 0.01–5 mcm, thickness of sublayer is 1–30 mcm, total thickness of membrane is 120–300 mcm, average pore diameter of sublayer is 3–60 nm, average diameter of the pores of substrate is 5–8 mcm.

EFFECT: technical result is providing a membrane which can be used to separate a mixture of liquid substances having similar boiling points, forming azeotropes, undergoing chemical conversions when heated to temperatures close to boiling points; concentrating aqueous solutions of organic substances, primarily aliphatic alcohols, in a wide range of concentrations, desalting solutions in the technology of producing medicines, alcoholic beverages and biofuel.

3 cl, 2 tbl, 18 ex

Description

Technical field

The invention relates to the field of chemistry of macromolecular compounds, more specifically to asymmetric polyvalent pervaporation membrane membranes.

The membranes obtained as a result of the invention can be used in the chemical, food, and pharmaceutical industries. Specifically, where it is necessary to selectively separate water from solutions of substances that undergo chemical transformations upon heating, in which water-alcohol mixtures having close boiling points forming azeotropes are used as solvent (dispersed medium), without using energy and material-intensive technologies to ensure the necessary separation efficiency. This is important, first of all, to increase the alcohol content in solutions containing up to 40 wt. % aliphatic alcohols - butanol, isopropanol and ethanol.

State of the art

In the chemical industry, rectification and distillation processes are traditionally widely used - the separation of pure components from liquid mixtures and solutions by repeated or single evaporation of a mixture of components and condensation of their vapors. The processes are universal for most liquid mixtures and solutions; standard equipment is used - distillation columns and distillation plants; however, one of the main technological conditions is the selection of specific process parameters, such as temperature and pressure. However, not all liquid mixtures and solutions can be separated by distillation or distillation, there are significant exceptions. An urgent problem is the increase in the content of alcohol or other organic components in aqueous-organic solutions of substances undergoing chemical transformations when heated. This problem in some cases can be solved by pervaporation, or evaporation through the membrane. By pervaporation is understood the mass transfer of liquid substances through a diffusion type membrane under the influence of a difference in the values of the chemical potential, accompanied by a change in the phase state of the penetrating components [Baker, Richard W. Membrane technology and applications / Richard W. Baker. - 2nd ed. / John Wiley & Sons Ltd, Chichester, England, 2004]. The pervaporation process proceeds under milder conditions and with less energy consumption than rectification and distillation processes. Pervaporation is 2-4 times more effective due to a decrease in the enthalpy of evaporation of the components through the membrane compared with free evaporation. A peculiarity of pervaporation is the need to create a specific membrane for a specific task, which does not detract from its importance. The key role belongs to membranes with high permeability and separation selectivity in combination with high mechanical and chemical resistance. As such membranes, asymmetric composite polymer pervaporation membranes are promising, consisting of interconnected forces of intermolecular interactions of three layers: a thin surface non-porous working selective diffusion layer (skin layer), a nanoporous sublayer and a microporous substrate - ultrafiltration membrane. In this case, an asymmetric membrane is understood to mean a polymer structure, the morphology of which changes in the direction perpendicular to the plane of the membrane, so that the pore size increases in the direction of flow of the separated liquids [RF patent No. 2126291].

As mentioned above, in the field of creating pervaporation membranes, there is an acute question of expanding the qualitative and quantitative range of separation of liquid mixtures and solutions by specific membranes, giving them universality. This is true for asymmetric composite polymer pervaporation membranes, especially when it comes to practical application. Thus, the concentration of a wide range of water-alcohol solutions of thermally unstable substances - for the pharmaceutical and food industries in the production of, for example, beer (more than 60 wt.% Water) or extracts from medicinal plant materials, when the target product cannot be subjected to high temperature treatment to preserve valuable components or obtaining bio-butanol and bio-ethanol is one of the most important modern tasks in solving the problem of separation of liquid mixtures by membranes.

Currently, for the separation of water-alcohol mixtures, polymer pervaporation membranes with working selective layers of polyvinyl alcohol are widely used [R.Y.M. Huang, Pervaporation Membrane Separation Processes, Membrane Science and Technology Series 1, Elsevier, Amsterdam, 1991] (for example, PERVAP brand membrane, Switzerland) of various polysaccharides [C.K. Yeom, J.G. Jegal, K.N. Lee, Characterization of relaxation phenomena and permeation behaviors in sodium alginate membrane during pervaporation separation of ethanol-water mixture, J. Appl. Polym. Sci. 62 (1996) 1561; W. Zhang, G.W. Li, Y.J. Fang, X.P. Wang, Maleic anhydride surface-modification of crosslinked chitosan membrane and its pervaporation performance, J. Membr. Sci. 295 (2007) 130], polysulfone [S.-H. Chen, K.-C. Yu, S.-S. Lin, D.-J. Chang, R.M. Liou, Pervaporation separation of water / ethanol mixture by sulfonated polysulfone membrane, J. Membr. Sci. 183 (2001) 294] and a number of other polymers. Known membranes tend to microbiologically contaminate (contamination of membrane material with microorganisms) [Demet CETIN, Sumru CITAK, Degradation of Polyvinyl Alcohol by a Mixed Microbial Culture Isolated from Paper Mill Treatment, Gazi University Journal of Science GU J Sci 27 (2): 839- 845 (2014)]. Often they can not be used to increase the alcohol content in mixtures of biological origin due to the non-affinity of the materials of the selective layer to the components of the separated mixtures. They are highly selective when concentrating liquid mixtures with a high content of organic component (less than 10 wt.% Water), but tend to lose selective properties for mixtures containing more than 60-90 wt. % of water and when heated, which greatly limits the scope of their application.

A promising class of polymers for producing asymmetric composite pervaporation membranes are mechanically, thermally, and chemically resistant polyimides.

It is known to use polyimides as materials for the manufacture of pervaporation membranes for the separation of an ethanol-water mixture containing 10 wt. % water [YC Wang, YS Tsai, KR Lee, JY Lai, Preparation and pervaporation per-formance of 3,3-bis 4- (4-aminophenoxy) phenyl phthalide based polyimide membranes, J. Appl. Polym. Sci. 96 (2005) 2046; YX Xu, CX Chen, JD Li, Experimental study on physical properties and per-vaporation performances of polyimide membranes, Chem. Eng. Sci. 62 (2007) 2466]. Known materials have high separation selectivity, but very low specific productivity, which in turn leads to low values of the efficiency parameter PSI (Pervaporation Separation index) PSI = J (α-1), where J is the total specific flow during separation of the mixture kg / (m ² h), α-separation factor).

Known membranes are not used for the concentration of water-alcohol solutions of thermally unstable substances due to low performance values.

An asymmetric membrane is known from a polymer composite based on PI-2080 polyimide and polyimide obtained by polycondensation of pyromellitic dianhydride and 4,4'-oxydianiline. [N. Yanagishita, D. Kitamoto, K. Narahua, T. Nakane, T. Okada, N. Matsuda, Y. Idemoto, N. Koura, Separation performance of polyimide composite membrane prepared by dip coating process, Journal of Membrane Science 188 (2001) 165-172.] The manufacture of the membrane material occurs by forming an asymmetric pervaporation membrane with a diffusion layer of PI-2080 polyimide, which is then lowered into a solution of the triethylammonium salt of the corresponding polyamide acid in methanol, and then subjected to thermal imidization. The maximum value of the PSI efficiency parameter (159.8) is achieved for the membrane during separation of the alcohol-water mixture containing 95 wt. % ethanol treated with 5 wt. % polyamic acid (with a specific reduced productivity of 0.2 kg 0,2mkm / (m ² ⋅h) and a separation factor of 800). The publication does not contain information about the study of their selectivity with respect to solutions containing more than 60 wt. % water, and upon separation of other aqueous-alcoholic solutions, for example, isopropanol with water. There is no information on the separation of mixtures of water with other organic liquids and aqueous-organic solutions, for example, in the concentration of alcoholic beverages.

No cost-effective analogues of perimodal membranes based on polyimides for the selective separation of water from aqueous-organic solutions containing up to 40 wt. % organic component.

Analysis of known analogues based on polyimides showed that the problem of combining high selectivity and performance of pervaporation membranes in relation to mixtures of aliphatic alcohols with water and, especially, when concentrating mixtures containing more than 60 wt. % water not resolved. Thus, the problem of creating universal effective membranes for aqueous mixtures of the entire range of aliphatic alcohols and other organic liquids and in a wide range of their concentrations remains relevant. Summarizing, it can be stated that universal pervaporation membranes for increasing the mass fraction of the organic component in aqueous-organic solutions and mixtures containing more than 60 wt. % water.

Disclosure of Invention

The task of the invention is the creation of an effective universal pervaporation membrane to increase the mass content of the organic component in aqueous-organic solutions and mixtures containing up to 40 wt. % of the organic component, which also contain, in addition to the organic component and water, substances that undergo chemical transformations when heated, primarily to concentrate aqueous mixtures of organic substances, primarily aliphatic alcohols, in a wide range of concentrations in the technology for producing medicines, alcoholic beverages, and biofuels.

This problem is solved by the claimed invention is an asymmetric composite polymer pervaporation membrane.

The inventive membrane is characterized by the following set of essential features:

1. A composite asymmetric polymer pervaporation membrane, characterized in that it consists of a non-porous working selective diffusion layer formed of polyimide with the link formula:

m: n = 0-2,

or its salt form with ions of triethylammonium, alkali and / or alkaline earth metals, or its crosslinked aromatic diamine form, nanoporous sublayer and microporous substrate, together constituting an ultrafiltration membrane substrate made of the same polyimide or another polymer used for the manufacture of ultrafiltration membranes, the thickness of the working layer is 0.01-5 microns, the thickness of the sublayer is 1-30 microns, the total thickness of the membrane is 120-300 microns, the average pore diameter of the sublayer is 3-60 nm, the average pore diameter of the sub LCD - 5-8 microns.

2. The asymmetric polymer pervaporation membrane according to claim 1, characterized in that the polymer used for ultrafiltration membranes is a polymer from the series:

polyamidoimide with the formula of the link:

polyacrylonitrile, regenerated cellulose, its acetates, polyvinyl chloride, polyethylene terephthalate, polysulfone, Ultem polyetherimide, Torlon polyamidoimide or similar in structure.

3. The asymmetric polymer pervaporation membrane according to claim 1, characterized in that the forms of the copolyimide or its salts crosslinked by the aromatic diamine are crosslinked based on the aromatic diamine from the series containing R ₁ , R ₂ , R ₃ , R ₄ in the structure.

The inventive asymmetric polymer pervaporation membrane is a membrane with a thin smooth surface non-porous working diffusion layer interconnected with it by the forces of intermolecular interaction (adhesion, cohesion) by a nanoporous sublayer, while the sublayer has through pores that cross the entire cross-section of the membrane and decrease towards a working layer interconnected with it by the cohesion forces of a microporous substrate — an ultrafiltration membrane with an asymmetric pore structure in pepper section.

The set of essential features of the claimed membrane provides a technical result - the creation of pervaporation membranes with an improved set of properties (higher level of PSI efficiency, mechanical strength, inertness to the components of mixtures, microbiological contamination, thermal and chemical resistance), allowing them to be used for the separation of water-organic mixtures, in a wide range of quantitative composition of these mixtures, mainly with a content of more than 60 wt. % water.

The inventive membrane differs from the known original polymer composition of the working selective diffusion layer, sublayer and quantitative characteristics (layer thickness, pore size of the sublayer).

Analysis of the prior art did not allow to find a solution that completely coincides in the totality of essential features with the claimed, which may indicate its novelty.

Only the combination of essential features of the claimed membrane allows to achieve the specified technical result. It was unexpected that the parameter of separation efficiency increases with increasing mass fraction of the organic component in the mixture, which allows the separation of these mixtures with a high separation efficiency of PSI exceeding the known membranes.

This allows us to assert that the claimed membrane meets the eligibility condition "inventive step" ("non-obviousness").

To confirm the compliance of the claimed invention to the requirement of "industrial applicability" we give examples of specific implementations.

Gmehling, Study of the Dehydration of Isopropanol by a Pervaporation Based Hybrid Process, Chem. Eng. Technol., 29 (2006), №. 4, 473-480; Wulin Qiu, Madhava Kosuri, Fangbin Zhoul, William J. Koros, Dehydration of ethanol-water mixtures using asymmetric hollow fiber membranes from commercial polyimides, Journal of Membrane Science 327 (2009) 96-103] описаны их транспортно-селективные свойства при разделении различных водно-спиртовых смесей.As the comparison membranes, a polymer pervaporation membrane with a working selective layer based on PERVAP 2201 polyvinyl alcohol and asymmetric membranes based on the commercially available Matrimid polyimide made by DeltaMem (Switzerland) was selected. In the literature [D. Van Baelen, A. Reyniers, B. Van der Bruggen, C. Vandecasteele, Pervaporation of Binary and Ternary Mixtures of Water with Methanol and / or Ethanol, Separation Science and Technology, J. Degreve, 39, (2005), No. 3, 563-580; Maria Teresa Sanz and

Gmehling, Study of the Dehydration of Isopropanol by a Pervaporation Based Hybrid Process, Chem. Eng. Technol., 29 (2006), No. 4, 473-480; Wulin Qiu, Madhava Kosuri, Fangbin Zhoul, William J. Koros, Dehydration of ethanol-water mixtures using asymmetric hollow fiber membranes from commercial polyimides, Journal of Membrane Science 327 (2009) 96-103] describes their transport-selective properties when different water-alcohol mixtures.

According to the manufacturer, the PERVAP 2201 membrane is suitable for the separation of water-alcohol mixtures containing up to 90 wt. % water at temperatures not higher than 100 ° C in the pH range of 5-8.

Membrane production is carried out according to the known method [Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review Gregory R. Guillen, Yinjin Pan, Minghua Li, and Eric M. V. Hoek, Ind. Eng. Chem. Res. (2011) 50, 3798-3817].

The copolyimides were obtained using the polycondensation reaction from the corresponding tetracarboxylic acid dianhydride and aromatic diamines [Polyimides - a class of heat-resistant polymers / Bessonov MI, Koton MM, Kudryavtsev VV, Laius L.A. - L .: Nauka, 1983. - 328 p.].

Example 1

Membrane with a selective layer of homopolymer (m = 0).

Из полиамидокислоты (ПАК) на основе 4,4'-оксидианилина и пиромеллитового ангидрида, которая в процессе имидизации преобразуется в полиимид селективного слоя, в форме соли с триэтиламмонием готовят 2%-ный раствор в воде, который далее использован для получения селективного слоя.

From a polyamide acid (PAA) based on 4,4'-oxydianiline and pyromellitic anhydride, which is converted into a selective layer polyimide during imidization, a 2% solution in water is prepared in the form of a salt with triethylammonium, which is then used to obtain a selective layer.

Из полиамидоимида (ПАИ) с R₁ готовят 10%-ный раствор в N-метилпирролидоне (N-МП). Раствор наносят на гладкую стеклянную подложку с помощью рекельного ножа с размером щели 190 мкм, проводят предформование при комнатной температуре в течение 10-20 мин. Предформованный раствор на подложке опускают в осадительную ванну (в качестве осадителя используют воду), полученную ультрафильтрационную мембрану сушат при комнатной температуре 1 ч.

A 10% solution in N-methylpyrrolidone (N-MP) is prepared from polyamidoimide (PAI) with R ₁ . The solution is applied to a smooth glass substrate using a rekel knife with a slit size of 190 microns, preforming is carried out at room temperature for 10-20 minutes. The preformed solution on the substrate is immersed in a precipitation bath (water is used as the precipitant), and the obtained ultrafiltration membrane is dried at room temperature for 1 h.

Наносят раствор ПАК на поверхность ультрафильтрационной мембраны и сушат при комнатной температуре 1-3 ч. Проводят имидизацию поверхностного слоя при 200°С на протяжении 1-4 ч, получают асимметричную первапорационную мембрану с толщиной селективного слоя 1 мкм, подслоя - 20 мкм, общей толщиной 180 мкм. Средний диаметр пор подслоя 3-60 нм, подложки - 5-8 мкм.

The PAA solution is applied to the surface of the ultrafiltration membrane and dried at room temperature for 1-3 hours. The surface layer is imidized at 200 ° C for 1-4 hours, an asymmetric pervaporation membrane is obtained with a selective layer thickness of 1 μm, a sublayer of 20 μm, and a total thickness 180 microns. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The resulting membrane has the following transport-selective properties in relation to the separation of aqueous-organic mixtures and solutions at 40 ° C:

- in the separation of water-alcohol mixtures containing up to 40 wt. % ethanol or isopropanol, specific productivity 0.240-0.697 kg / (m ² ⋅ h), separation factor 100-1000.

- when separating a water-alcohol mixture containing 33 wt. % ethanol, specific productivity 0.380 kg / (m ² ⋅ h), separation factor (calculation according to ethanol) - not less than 1000.

- when separating a water-alcohol mixture containing 9 wt. % ethanol, specific productivity 0.697 kg / (m ² ⋅ h), separation factor (calculation according to ethanol) - not less than 499.

- when separating an aqueous-organic mixture (beer drink, ethyl alcohol content 5 vol.%), specific productivity - 0.401 kg / m ² ⋅h, separation factor (calculation for ethanol) - not less than 900, for other components - not less than 200 .

The values of the efficiency parameter PSI (296.8 for 33 wt.% Ethanol; 347.8 for 9 wt.% Ethanol) of the obtained membrane are superior to those for the comparison membranes PERVAP 2201 (PSI - 13) and membranes based on Matrimid (PSI - 89.7 ) in the separation of water-alcohol mixtures. In this case, the value of a higher efficiency parameter is achieved at 40 ° C (PERVAP - 60 ° C), which ensures higher energy efficiency of the process when using the claimed membrane.

The obtained membrane, like all membranes described below in Examples Nos. 2-19, retain mechanical strength and chemical resistance over a wider temperature range (up to 200 ° C) and pH 2-8.

Example 2

Membrane with a selective layer of copolymer (m: n = 0.42).

The membrane is obtained according to example 1.

In the preparation of the PAA solution, copolyamidic acid based on 4,4'-oxydianiline, 3,5-diaminobenzoic acid and pyromellitic anhydride is used (m: n = 0.42).

After imidization of the surface layer, the membrane is treated with a 0.05 M sulfuric acid solution for 24 hours, washed with distilled water until a neutral pH of the washing water is reached, and air dried for 1-2 hours. An asymmetric pervaporation membrane with a selective layer thickness of 1 μm is obtained, sublayer 1 microns, a total thickness of 120 microns. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The properties of the obtained membrane are similar to the properties of the membrane in example 1, an increase in productivity is observed up to 0.4-1 kg / m ² h with a certain decrease in selectivity, which does not significantly affect the efficiency parameter (100-260).

Example 3

Membrane with a selective layer of a copolymer (m: n = 2) with triethylammonium ions.

The membrane is obtained according to example 2 from PAA (m: n = 2), however, the membrane is not treated with a solution of sulfuric acid. An asymmetric pervaporation membrane is obtained with a selective layer thickness of 1 μm, a sublayer of 30 μm, and a total thickness of 200 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The properties of the obtained membrane are similar to the properties of the membrane in example 2, there is a slight increase in productivity (0.41-1.2) with a decrease in selectivity (separation factor 80), which do not significantly affect the PSI efficiency parameter.

Example 4

Membrane with a selective layer of a copolymer (m: n = 0.42) with potassium or sodium ions.

The membrane is obtained according to example 2, after processing the membrane with a solution of sulfuric acid, it is treated with a 0.05 M solution of potassium or sodium hydroxide in ethanol for 24 hours. An asymmetric pervaporation membrane is obtained with a selective layer thickness of 1 μm, a sublayer of 30 μm, a total thickness of 200 μm . The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 3.

Example 5

Membrane with a selective layer of a copolymer (m: n = 2) with calcium ions.

The membrane is obtained according to example 2 from PAA (m: n = 2), after treating the membrane with a solution of sulfuric acid, it is treated with a 0.5 M solution of calcium chloride in water for 24 hours. An asymmetric pervaporation membrane with a selective layer thickness of 1 μm is obtained, sublayer is 30 microns, a total thickness of 200 microns. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 4.

Example 6

A membrane with a substrate of the same polymer as the selective layer.

The membrane is obtained according to example 5 with a selective layer of copolyimides (m: n = 0-2). The substrate is obtained from a solution of 10-15 wt. % co-PAA (m: n = 0-2) in N-MP, after molding it is imidized at a temperature of 200 ° C for 4 hours, after which a coating solution of co-PAA (m: n = 0-2) is applied according to example 1 and imidize it at a temperature of 200 ° C for 4 hours

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 1 μm, a sublayer of 20 μm, and a total thickness of 200 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 2

Example 7

Membrane with Torlon polymer backing.

The membrane is obtained according to example 5. The substrate is obtained from a solution of 10-15 wt. % Torlon in N-MP.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 4 μm, a sublayer of 20 μm, and a total thickness of 200 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 1.

Example 8

Membrane with polyacrylonitrile backing.

The membrane is obtained according to example 5, while the polyacrylonitrile is dissolved in N-MP.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 5 μm, a sublayer of 20 μm, and a total thickness of 180 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in examples 1-2.

Example 9

A membrane with a regenerated cellulose backing.

The membrane is obtained according to example 5, while the cellulose acetate is dissolved in dichloromethane, then the acetate is regenerated to cellulose with a 0.5 M sulfuric acid solution.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 4 μm, a sublayer of 20 μm, and a total thickness of 300 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 1.

Example 10

Membrane with a cellulose acetate backing.

The membrane is obtained according to example 7, while the cellulose acetate is dissolved in dichloromethane.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 4 μm, a sublayer of 20 μm, and a total thickness of 180 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 1.

Example 11

Polyvinyl chloride backed membrane.

The membrane is prepared according to Example 5, wherein the polyvinyl chloride is dissolved in N, N-dimethylacetamide.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 5 μm, a sublayer of 10 μm, and a total thickness of 170 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 1.

Example 12

Membrane with a polyethylene terephthalate substrate.

The membrane is obtained according to example 5, while diethylene terephthalate is dissolved in trifluoroacetic acid.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 4 μm, a sublayer of 20 μm, and a total thickness of 180 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 2.

Example 13

Membrane with polysulfone backing.

The membrane is obtained according to example 5, while the polysulfone is dissolved in N-MP.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 4 μm, a sublayer of 20 μm, and a total thickness of 180 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in examples 1-2.

Example 14

Membrane with Ultem polyetherimide backing.

The membrane is obtained according to example 7, while the Ultem polyetherimide is dissolved in N-MP.

An asymmetric pervaporation membrane is obtained with a selective layer thickness of 5 μm, a sublayer of 20 μm, and a total thickness of 170 μm. The average pore diameter of the sublayer is 3-60 nm, the substrate is 5-8 microns.

The membrane has properties at the level of membrane properties described in example 2.

Example 15

A membrane in which all layers are made of homopolyimide (m = 0) in salt form with triethylammonium ions crosslinked with diamine (R 1).

The membrane is obtained according to example 1, then the membrane is treated with 10 wt. % solution of oxydianiline in methanol for 25-60 minutes, and dried in air for 1-2 hours

The properties of the obtained membrane are similar to the properties of the membrane described in Example 1. When separating the azeotropic water-ethanol mixture (33 wt.% Ethanol) at 40 ° C, a decrease in productivity is observed to 0.3 kg / (m ² h) with an increase in the separation factor to 1200, while the PSI performance parameter increases to 359.7.

Examples 16-18.

Membranes in which the selective layer is made of copolyimide (m: n = 0.2) in salt form with diamine crosslinked triethylammonium ions (with R ₂ or R ₃ or R ₄ ). The membrane is obtained according to example 15.

The properties of the membranes obtained according to Example 16-18 are similar to the properties of the membrane described in Example 15. When separating the azeotropic water-ethanol mixture at 40 ° C, a decrease in productivity is observed to 0.3-0.34 kg / (m ² h) with increasing factor separation up to 1200, while the PSI efficiency parameter changes to 359.7-407.7.

The implementation of the claimed invention is not limited to the above examples.

Going beyond the boundaries of the claimed intervals leads to the inability to implement the invention.

The inventive membrane can be used to separate a mixture of liquid substances having close boiling points, forming azeotropes, undergoing chemical transformations when heated to temperatures close to boiling points; concentration of aqueous solutions of organic substances, primarily aliphatic alcohols, in a wide range of concentrations, desalination of solutions in the technology for producing medicines and alcoholic beverages.

Claims (9)

1. A composite asymmetric polymer pervaporation membrane, characterized in that it consists of a non-porous working selective diffusion layer formed of polyimide with the link formula:

m: n = 0-2, or its salt form with ions of triethylammonium, alkali and / or alkaline earth metals, or its crosslinked aromatic diamine form, nanoporous sublayer and microporous substrate, together constituting an ultrafiltration membrane substrate made of the same polyimide or another polymer used for the manufacture of ultrafiltration membranes, the thickness of the working layer is 0.01-5 microns, the thickness of the sublayer is 1-30 microns, the total thickness of the membrane is 120-300 microns, the average pore diameter of the sublayer is 3-60 nm, the average pore diameter of the sub ki - 5-8 microns. 2. The asymmetric polymer pervaporation membrane according to claim 1, characterized in that the polymer used for ultrafiltration membranes is a polymer from the series: polyamidoimide with the formula of the link:

polyacrylonitrile, regenerated cellulose, its acetates, polyvinyl chloride, polyethylene terephthalate, polysulfone, Ultem polyetherimide, Torlon polyamidoimide. 3. The asymmetric polymer pervaporation membrane according to claim 1, characterized in that the forms of the copolyimide or its salts crosslinked by the aromatic diamine are crosslinked based on the aromatic diamine from the series containing R ₁ , R ₂ , R ₃ , R ₄ in the structure.