RU2753406C1 - Asymmetrical polymer pervaporation membrane - Google Patents

Abstract

FIELD: membranes.

SUBSTANCE: invention relates to membrane technology. Described is an asymmetrical polymer pervaporation membrane including a consequently selective layer, a nanoporous sublayer and a microporous substrate, with a total thickness of 100 to 120 mcm, the selective layer is made of a polymeric polyurethane composition containing polyoxyethylene glycol with a molecular weight of 400, an aromatic isocyanate and a solvent; according to the invention, as an aromatic isocyanate, the composition comprises a polyisocyanate based on 4,4'-diphenylmethane diisocyanate, as a solvent the composition comprises acetone, and additionally comprises orthophosphoric acid and triethanolamine, at the following ratio of components, pts. wt.: polyoxyethylene glycol with a molecular weight of 400 - 100, polyisocyanate based on 4,4'-diphenylmethane diisocyanate 100 to 110, acetone 14 to 18, orthophosphoric acid 10 to 15, triethanolamine 6 to 8.

EFFECT: increased pervaporation separation index of the membrane.

1 cl, 1 tbl, 8 ex

Description

The invention relates to membrane technology, specifically to asymmetric polymeric pervaporation membranes with a selective layer of polymeric polyurethane composition and can be used for separating isopropanol-water mixture in chemical, food, pharmaceutical and other industries.

The Pervaporation Separation Index (PSI), a measure of its separation capacity, includes the membrane separation factor (1) and specific productivity (2). The pervaporation separation index can be used to judge the effectiveness of the membrane, which makes it possible to select a membrane with the optimal PSI value.

1) The separation factor is the separation efficiency of the pervaporation membrane system. The split ratio can be calculated according to the equation:

массовые доли компонентов в пермеате, P_IP F_IP массовые доли компонентов в ретанте (сырье), соответственно.in which

mass fractions of components in the permeate, P _IP F _IP mass fractions of components in the retant (raw material), respectively.

2) Specific performance of the membrane:

The specific performance of a membrane is the number of components that penetrate through a certain membrane surface area in a given unit of time. Membrane specific performance is measured by the permeability flow J, which links the product flow to the membrane area required to achieve separation.

Specific productivity can be determined gravimetrically and calculated according to the equation:

where Δg is the total amount of permeate (l or kg), S is the effective membrane surface area (m ² ), and Δt is the penetration time (h).

(3) Pervaporation membrane separation index

The membrane pervaporation separation index (PSI) can be expressed by the equation:

PSI = J (α-l),

where J - specific productivity, kg / m ² h

α - membrane separation factor

The higher the Pervaporation Separation Index (PSI) value, the higher the membrane efficiency.

Pervaporation separation using polymer membranes is promising in the processes of isopropanol (IP) dehydration. The use of traditional separation methods in this case is economically impractical and leads to environmental pollution. Isopropanol is widely used in modern semiconductor and microelectronic industries as a solvent and cleaning agent, as a polymerization modifier, deicing agent and preservative, as an aerosol solvent in medicine, as well as in the extraction and purification of natural products.

Typically, the membrane thickness is 50-300 microns, which provides sufficient mechanical strength, to increase which, in real technology, a nonwoven base is used.

The demand for isopropanol is growing every year, which contributes to an increase in the price of the pure substance. In addition, isopropanol waste is extremely harmful to the environment and requires high disposal costs. Regeneration using an asymmetric polymer pervaporation membrane and reuse is important from both economic and environmental points of view.

The concentrations of substances in the mixture to be separated directly affect the sorption behavior at the interface between the membrane and the liquid, as well as the diffusion of the component through the membrane.

Pervaporation membranes with a selective polyurethane layer are stable in a variety of solvents and also have improved performance over commercially available membranes. Polyurethane film is an extremely wear-resistant material that can ensure long-term use of membranes in a permanent industrial production environment.

Known polymer pervaporation membrane, which includes a sequentially selective layer, a nanoporous sublayer and a microporous substrate, with a total thickness of 90-100 microns, the selective layer of which is made of a polymer polyurethane composition containing polybutadiene, 1,4-butanediol, a hardener aromatic isocyanate based on 4.4 ' -dicyclohexylmethane, as well as the catalyst dibutyldilaurate tin.

When the content of the mixture to be separated isopropanol: water, water 10 wt. % separation coefficient and specific productivity of the membrane are 175 and 0.320 kg / m ² h, respectively, the pervaporation separation index (PSI) is 55.7.

The disadvantage of the known polymer pervaporation membrane is an insufficiently high pervaporation separation index (PSI), see Shih-Liang Huang, Po-Hsueh Chang, Mei-Hui Tsai, Huang-Chen Chang // Properties and pervaporation performances of crosslinked TPB-based polyurethane membranes / Separation and Purification Technology Vol. 56, No. 56, pp. 63-70, 2007.

Known polymeric pervaporation membrane, which includes a sequentially selective layer, a nanoporous sublayer and a microporous substrate, the selective layer of which is made of a polymeric polyurethane composition containing an oligodiol based on hydroxyl-terminated polybutadiene (with a molecular weight of 1333 g / mol), butanediol-1,4, a hardener - aromatic isocyanate based on 4,4'-dicyclohexylmethane, the solvent is a mixture of toluene and dimethylformamide, and the catalyst is dibutyl tin dilaurate.

When the content of the mixture to be separated isopropanol: water, water 10 wt. % separation factor and specific productivity of the membrane are 225 and 0.375 kg / m ² h, respectively, the pervaporation separation index (PSI) is 84.3.

The disadvantage of the known polymeric pervaporation membrane is the insufficiently high pervaporation separation index (PSI), see Mei-Hui Tsai, Shih-Liang Huang, Po-Hsueh Chang, Chiou-Jey Chen // Properties and pervaporation separation of hydroxyl-terminated polybutadiene-based polyurethane / poly (methyl metharcylate) interpenetrating networks membranes / Journal of Applied Polymer Science, Vol. 106, pp. 4277-4286, 2007.

Known polymer pervaporation membrane, which includes a sequentially selective layer, a nanoporous sublayer and a microporous substrate, the selective layer of which is made of a polymer polyurethane composition containing hydroxyl-terminated polybutadiene (with a molecular weight of 1333 g / mol), butanediol-1,4, a hardener - aromatic isocyanate based on 4,4'-dicyclohexylmethane and benzoyl peroxide, as well as the catalyst dibutyl tin dilaurate.

When the content of the separated mixture of water is 20 wt. % separation factor and membrane specific productivity are 4.67 and 1.583 kg / m ² h, respectively, the pervaporation separation index (PSI) is 5.8.

The disadvantage of the known pervaporation membrane is the low PSI, see Min-Shiun Chao, Shih-Liang Huang // Epoxidized HTPB-based Polyurethane Membranes for Pervaporation Separation / Journal of the Chinese Chemical Society, Vol. 52, pp. 287-294, 2005.

The closest in technical essence is an asymmetric polymeric pervaporation membrane, which includes a selective layer in series, a nanoporous sublayer and a microporous substrate, with a total thickness of 100-120 microns, the selective membrane layer is made of a polymeric polyurethane composition containing polyoxyethylene glycol with a molecular weight of 400, an aromatic isocyant based on 2 , 4-toluene diisocyanate, catalyst is dibutyl tin dilaurate and tetrahydrofuran as a solvent, with the following ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 2,4-toluene diisocyanate ten dibutyl tin dilaurate 0.08 specified solvent 54.4

The polyurethane layer obtained at the indicated ratios of the components is further exposed to a temperature equal to 80 ° C for 5 hours.

When separating a mixture of isopropanol: water using the specified asymmetric polymeric pervaporation membrane, with a content of 20 wt. %, the separation factor is 4.6, the specific productivity of the membrane is 0.081 kg / m ² h, the pervaporation separation index (PSI) of the membrane PSI is 0.37, see Swatilekha Das, Suparna Sarkar, Piyali Basak and Basudam Adhikari // Dehydration of alcohols by pervaporation using hydrophilic polyether urethane membranes / Journal of Scientific and Research, Vol. 67, pp. 219-227, 2008

The disadvantage of the known asymmetric polymeric pervaporation membrane is the low pervaporation separation index of the isopropanol-water mixture, which is 0.37.

A technical problem is the low value of the membrane pervaporation separation index (PSI).

The technical problem of increasing the PSI membrane pervaporation separation index is solved by the fact that an asymmetric polymeric pervaporation membrane, including a selective layer, a nanoporous sublayer and a microporous substrate, with a total thickness of 100-120 μm, the selective layer is made of a polymeric polyurethane composition containing polyoxyethylene glycol with a molecular weight of 400 aromatic isocyanate and a solvent, according to the invention, as an aromatic isocyanate, the composition contains a polyisocyanate based on 4,4'-diphenylmethane diisocyanate, as a solvent contains acetone and additionally contains orthophosphoric acid and triethanolamine, in the following ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100-110 acetone 14-18 orthophosphoric acid 10-15 triethanolamine 6-8

Solution of the technical problem allows to significantly increase the separation factor, specific productivity and pervaporation separation index (PSI) of an asymmetric polymeric pervaporation membrane.

Characteristics of substances and materials used in the claimed asymmetric polymer pervaporation membrane:

- polyoxyethylene glycol with a molecular weight of 400 produced by OAO Nizhnekamskneftekhim, Russia;

- ortho-phosphoric acid in accordance with GOST 6552-80;

- triethanolamine, produced by Kazanorgsintez PJSC, Russia TU 2423-168-00203335-2007;

- polyisocyanate based on 4,4'-diphenylmethane diisocyanate brand Wannate PM-200, manufactured by Wanhua-Borsodchem, China;

- acetone in accordance with GOST 2603-79;

- nanoporous fluoroplastic coating F42L with a thickness of 20-25 microns and a porosity of 0.05 nm, "Vladipor", Russia;

- microporous substrate made of lavsan-propylene cloth with a thickness of 40-80 microns, "Vladipor", Russia.

To separate a two-component mixture of isopropanol: water, the claimed asymmetric polymeric pervaporation membrane includes a selective layer made of a polymeric polyurethane composition, a nanoporous sublayer of fluoroplastic F42L, and a microporous substrate based on polypropylene and lavsan.

To form a selective layer of an asymmetric polymeric pervaporation membrane, polyoxyethylene glycol with a molecular weight of 400, orthophosphoric acid and triethanolamine are first mixed at a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 10-15 triethanolamine 6-8,

the resulting mixture was heated under vacuum at 2 mm. Hg at a temperature of 80 ° C for 2 hours, then placed in a container into which acetone is introduced and, with stirring, a polyisocyanate based on 4,4'-diphenylmethane diisocyanate is introduced with the following ratio of components, wt. h .:

polyisocyanate based 4,4'-diphenylmethane diisocyanate 100-110 acetone 14-18

A selective membrane layer is formed from the obtained polymeric polyurethane composition by applying it to the surface of a nanoporous sublayer of a microporous substrate made of lavsan-propylene cloth, followed by curing under normal conditions for 48 hours.

The asymmetric polymeric pervaporation membrane obtained in this way is intended for the separation of a two-component mixture of isopropanol: water.

The invention is illustrated by the following examples of specific implementation:

Example 1

To separate a two-component mixture of isopropanol: water, an asymmetric polymeric pervaporation membrane is used, including a sequentially selective layer 20 μm thick made of a polymeric polyurethane composition, a nanoporous sublayer of fluoroplastic F42L with a pore size of 50 nm and a thickness of 20 μm, and a microporous substrate based on polypropylene and lavsan 60 microns thick with a total porosity of 80%.

To form a selective layer of an asymmetric polymeric pervaporation membrane, polyoxyethylene glycol with a molecular weight of 400, orthophosphoric acid and triethanolamine are first mixed at a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid ten triethanolamine 6,

the resulting mixture was heated under vacuum at 2 mm. Hg at a temperature of 80 ° C for 2 hours, then placed in a container into which acetone is introduced and, with stirring, a polyisocyanate based on 4,4'-diphenylmethane diisocyanate is introduced with the following ratio of components, wt. h .:

polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

A selective membrane layer is formed from the obtained polymeric polyurethane composition by applying it to the surface of a nanoporous sublayer, followed by curing under normal conditions for 48 hours.

The thickness of the selective layer is 20 microns, the thickness of the nanoporous layer is 20 microns, the thickness of the polypropylene-lavsan substrate is 60 microns. The total thickness of the asymmetric polymeric pervaporacinone membrane is 100 µm.

The asymmetric polymeric pervaporation membrane thus obtained has the following separation characteristics:

When separating a binary mixture of isopropanol: water with a water content of 20% at a temperature of 30 ° C, the separation factor is 105 with a productivity of 0.704 kg / m ² h. The PSI value in this case is 73.2.

Example 2 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 12.5 triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 20% at a temperature of 40 ° C, the separation factor is 104, the specific productivity is 0.904 kg / m ² h. The PSI value is 93.1.

Example 3 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid ten triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 15% at a temperature of 40 ° C, the separation factor is 148, the specific productivity is 0.805 kg / m ² h. The PSI value is 119.1

Example 4 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 15 triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 15% at a temperature of 40 ° C, the separation factor is 155, the specific productivity is 0.974 kg / m ² h. The PSI value is 149.9

Example 5 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 12.5 triethanolamine eight polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 15% at a temperature of 60 ° C, the separation factor is 71, and the specific productivity is 2.298 kg / m ² h. The PSI value is 163.1.

Example 6 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 12.5 triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 15% at a temperature of 60 ° C, the separation factor is 54, the specific productivity is 3.734 kg / m ² h. The PSI value is 201.6.

Example 7 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 12.5 triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 110 acetone fourteen

When separating a binary mixture of isopropanol: water with a water content of 10% at a temperature of 30 ° C, the separation factor is 189, and the specific productivity is 0.722 kg / m ² h. The PSI value is 135.7.

Example 8 is similar to example 1, with:

The selective layer of the asymmetric polymeric pervaporation membrane is made of a polymeric polyurethane composition with a ratio of components, wt. h .:

polyoxyethylene glycol with a molecular weight of 400 100 orthophosphoric acid 12.5 triethanolamine 6 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100 acetone eighteen

When separating a binary mixture of isopropanol: water with a water content of 10% at a temperature of 40 ° C, the separation factor is 145, the specific productivity is 1.254 kg / m ² h. The PSI value is 180.5.

Characteristics of an asymmetric polymer pervaporation membrane in the separation of a mixture of isopropanol: water with a water content of 10.15.20 wt. %, the selective layer of which is made of a polymeric polyurethane composition is presented in Table 1.

When comparing the indicators according to example 1 and according to the prototype when separating a binary mixture of isopropanol: water with a water content of 20% and a temperature of 30 ° C, the separation factor of the membrane is 105 compared to 4.6, the specific productivity, kg / m ² h is 0.704 versus 0.081 , the pervaporation separation index (PSI) of the membrane is 73.2 versus 0.37.

As can be seen from the presented examples of specific execution of Table 1, the separation efficiency of a binary mixture of isopropanol: water using the claimed asymmetric polymeric pervaporation membrane in comparison with the prototype is significantly superior in terms of the membrane separation factor, specific productivity and the membrane pervaporation separation index (PSI).

Claims (2)

An asymmetric polymeric pervaporation membrane, including a sequentially selective layer, a nanoporous sublayer and a microporous substrate, with a total thickness of 100-120 μm, the selective layer is made of a polymeric polyurethane composition containing polyoxyethylene glycol with a molecular weight of 400, an aromatic isocyanate and a solvent, characterized in that the aromatic isocyanate composition contains a polyisocyanate based on 4,4'-diphenylmethane diisocyanate, as a solvent contains acetone and additionally contains orthophosphoric acid and triethanolamine, in the following ratio of components, wt. h .: polyoxyethylene glycol molecular weight 400 100 polyisocyanate based 4,4'-diphenylmethane diisocyanate 100-110 acetone 14-18 orthophosphoric acid 10-15 triethanolamine 6-8