RU2489199C1 - Method of making antibacterial polymer membrane - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to membrane technology, particularly, to production of antibacterial polymer membranes to be used in water and aqueous solution treatment in food and pharmaceutical industries, and medicine. Proposed method comprises making polymer solution, forming of polymer membrane and processing with antibacterial substance. Produced membrane is dried, rinsed with water and subjected to final drying. Said antibacterial substance represents composition containing the following components in wt %: 5-10 of poorly soluble or insoluble slats of silver, 2-25 of formic acid an 65-93 of water.

EFFECT: prolonged antibacterial properties.

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Description

The invention relates to membrane technology and can find wide application for the purification of water and aqueous solutions in food, pharmaceutical, other industries, as well as medicine.

One of the most important problems of membrane technology is the decrease in membrane productivity due to the formation of various deposits on their surface. In contrast to the process of membrane contamination with colloidal and crystalline sediments, bacteria and microorganisms not only precipitate on the membrane surface, but also further multiply, grow through the pores and infect the filtrate. The use of various antibacterial (antimicrobial - hereinafter antibacterial) additives is a very promising method of combating biological pollution of polymer membranes.

A significant amount of natural and synthetic substances and compounds exhibits antibacterial activity, but only some of them can be used for immobilization on the surface of membranes. The following requirements may be presented to them:

- safety for the human body of bactericidal modifying agents in concentrations sufficient to suppress the vital activity of microorganisms;

- high activity of active substances and a wide range of their antibacterial effects, which must be maintained during the required period of operation,

The emergence of new bacterial strains resistant to traditional antibiotics has become a serious problem for maintaining people's health; this fact served as a powerful incentive for the development of new bactericides. It is known that silver and some of its salts are highly toxic to most microorganisms; for this reason, silver in various modifications, as well as compositions containing silver, are widely used as antibacterial additives.

To this problem of the use of silver and its preparations, interest is not weakening at the present time: many publications are devoted to it, for example, “Silver nanoparticles as antimicrobial agents”, publ. in Colloid and Interface Science in 2004 (275, 177-182). "Polysulfone ultrafiltration membranes impregnated with silver nanoparticles to remove viruses with high resistance to biocontamination", publ. in the “Water Research / Journal of the International Water Association” in 2009 (No. 43 pp. 715-723), an article by Russian scientists “Silver with delivery to the cage” (published on the website of ARGO). The above scientific works relate to methods for creating antibacterial drugs based on silver nanoparticles. The disadvantages of these developments are the technological difficulties of introducing silver nanoparticles in the required amount, as well as the decrease in the efficiency of their use due to leaching of nanoparticles from the polymer matrix of the membrane during its use.

Known application for US patent No. 201110024355 company Polymers CRC (publ. 2011) "Antimicrobial membranes." The invention relates to antimicrobial compositions for producing polymer membranes in gas and water purification, which are silver zeolites combined with zinc compounds, as well as elemental silver with a highly developed surface. The disadvantage of this solution is to reduce the stability of the antibacterial properties of the membrane during its use due to the gradual leaching of the applied compositions from the polymer matrix.

The closest technical solution to the claimed is a method of obtaining a polymer ultrafiltration and microfiltration membranes with high resistance to contamination by adding silver nanoparticles according to the application of Korea No. 20070071766 "Method for producing an asymmetric ultrafiltration and microfiltration membranes by introducing silver nanoparticles" (published in 2007) .). In accordance with the solution of the prototype, the claimed method includes preparing a polymer solution, mixing it with silver nanoparticles of 5-50 nm in size, subsequent deaeration of the resulting solution mixture, forming the membrane in accordance with conventional technology and drying it. The main disadvantages of the prototype are the following facts: 1. With the introduction of silver nanoparticles before forming the membrane, part of the silver nanoparticles is washed out, which reduces their total amount in the membrane; 2. In accordance with the stated sequence of stages of the particles of nano-silver. possessing antimicrobial action, get into the polymer matrix, as a result of which, when using a membrane with a filtered medium, only a small part of the nanoparticles is in contact, which reduces the effectiveness of their action.

The essence of the invention is as follows.

The technical problem to which the claimed invention is directed is the development of a composition for processing polymer membranes that confers antibacterial properties, as well as a sequence of stages for producing a polymer membrane, including the introduction of the specified composition.

The technical result of the claimed invention is to increase the duration of the antibacterial properties of the obtained polymer membrane.

The claimed technical result is achieved by preparing a polymer solution, molding a polymer membrane, treating the resulting membrane with an antibacterial substance, drying, washing and final drying, while the following composition is used as an antibacterial substance (parts by weight):

Silver salt slightly soluble or insoluble 5-10;

Formic acid 2-25;

Water is the rest.

Additional studies conducted by the applicant showed that the use of a composition containing water, sparingly soluble or insoluble silver salts, as well as formic acid in a given concentration promotes the "ingrowth" of silver salts into the polymer matrix membrane due to the partial swelling of the polymer as a result of its interaction with formic acid and, as a consequence, the strengthening of adhesive processes. The claimed sequence of stages, involving treatment with an antibacterial composition after the formation of the membrane, allows the introduction of silver salts on the surface of the polymer matrix, which certainly improves the antibacterial properties of the resulting membrane. When using the obtained membrane in contact during operation with aqueous media, these reagents are practically not washed out.

The claimed invention is as follows.

A polymer membrane is formed by placing the polymer in a calculated amount of solvent, then it is cast onto an appropriate support and immersed in a coagulation bath containing a non-solvent (precipitant). (“Introduction to membrane technology.” M. Mulder, M., “Mir” 1999, p.96-97), after which they are placed in a pre-prepared composition containing (parts by weight): 2-25 formic acid, 5-10 silver salt, slightly soluble or insoluble in water, water (the rest) for 5-30 seconds. The membrane thus treated is dried at a temperature of 40-80 ° C, washed in running water from formic acid residues. then carry out the final drying. The result is an antibacterial polymer membrane, the properties of which are evaluated by filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli.

To implement the invention, the following substances can be used:

Silver salts, sparingly soluble or insoluble in water (Note: according to the generally accepted classification of the solubility of salts in water, salts are considered soluble if 1 g of the salt in 100 g of water is soluble, sparingly soluble if 0.001 g in 100 g of water is soluble, insoluble, if soluble less than 0.001 g in 100 g of water): in particular, silver bromide, silver bromate, silver sulfate, silver phosphate.

Formic acid GOST 1706-78.

Water.

Solvents and polymers needed to form the polymer membrane.

A specific implementation of the claimed invention is illustrated by the following examples.

Example 1

In accordance with the above method, a microfiltration polyamide membrane is formed by dissolving (mass parts): polyamide (16) in a mixture of formic acid (72) and water (12), followed by treatment with a precipitant - a mixture of water (60) and formic acid (40) . Microfiltration polyamide membrane is placed for 5 seconds in the solution. consisting of a mixture containing (parts by weight): 2 formic acid, 5 silver bromate (solubility in water at 20 ° C is 0.18 g / 100 ml), 93 water. Then the treated membrane is dried at a temperature of 50 ° C, washed in running water from acid residues. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli, inhibits bacterial growth for 10 days.

Example 2

In accordance with the above method, an ultrafiltration polyamide membrane is formed by dissolving (mass parts): polyamide (18) in a mixture of formic acid (72) and water (10), followed by treatment with a precipitant - water (100). The ultrafiltration polyamide membrane is placed for 20 seconds in a solution consisting of a mixture containing (parts by weight): 10 formic acid, 10 silver sulfate (solubility in water at 20 ° C is 0.79 g / 100 ml), 80 water. Then the treated membrane is dried at a temperature of 80 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli, inhibits bacterial growth for 10 days.

Example 3

In accordance with the above method, a microfiltration polyamide membrane is formed by dissolving (mass parts): polyamide (16) in a mixture of formic acid (72) and water (12), followed by treatment with a precipitant - a mixture of water (60) and formic acid (40) . Microfiltration polyamide membrane is placed for 15 seconds in the solution. consisting of a mixture containing (parts by weight): 15 formic acid, 7 silver phosphate (sparingly soluble in water), 78 water. Then the treated membrane is dried at a temperature of 60 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ KOE of E. coli, inhibits bacterial growth for 14 days.

Example 4

In accordance with the above method, an ultrafiltration polysulfonamide membrane is formed by dissolving (mass parts): polyamide (16) in a mixture of N, N-dimethylacetamide (83.5) and polyvinylpyorrolidone (0.5), followed by treatment with a precipitator of dimethylacetamide (83.5 ) and polyvinylpyorrolidone (0.5), followed by treatment with a precipitant - water (100). The ultrafiltration polysulfonamide membrane is placed for 30 seconds in a solution consisting of a mixture containing (mass parts): 20 formic acid, 8 silver bromide (insoluble in water), 72 water. Then the treated membrane is dried at a temperature of 40 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of the test culture containing 5 × 10 ³ CFU of E. coli, inhibits growth for 10 days.

Example 5

In accordance with the above method, a microfiltration polyethersulfone membrane is formed by dissolving (mass parts): polyethersulfone (16) in a mixture in a mixture of N, N-dimethylacetamide (83.5) and polyvinylpyrrolidone (0.5), followed by treatment with a precipitator - a mixture of water (50) and dimethylacetamide acid (500). Microfiltration polyethersulfone membrane is placed for 10 seconds in a solution consisting of a mixture. containing (mass parts): 5 formic acid, 10 silver sulfate (solubility at will 0.79 g / 100 ml), 85 water. Then the treated membrane is dried at a temperature of 70 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli, inhibits bacterial growth for 10 days.

Example 6

According. with the method described above, a microfiltration polyamide membrane is formed by dissolving (mass parts): polyamide (16) in a mixture of formic acid (72) and water (12), followed by precipitant treatment with a mixture of water (60) and formic acid (40). the polyamide membrane is placed for 30 seconds in the solution. consisting of a mixture containing (parts by weight): 25 formic acid, 10 silver phosphate (sparingly soluble in water), 65 water. Then the treated membrane is dried at a temperature of 70 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli, inhibits bacterial growth for 20 days.

Example 7

To obtain a nanofiltration polyamide membrane, an ultrafiltration membrane from aromatic polyamide is placed in an aqueous solution of 0.5% metaphenylenediamine, the excess solution is allowed to drain, and then it is placed in a solution of the mixture (parts by weight): isophthaloyl chloride and trimesoyl chloride (30) in hexane with a total concentration of 0 ,5%. incubated for 1 min, then washed with water and dried. The obtained nanofiltration polyamide membrane is placed for 30 seconds in a solution consisting of a mixture containing (mass parts): 10 formic acid, 8 silver sulfate (solubility in water at 20 ° C, 0.79 g / 100 ml), 82 water . Then the treated membrane is dried at a temperature of 90 ° C, washed in running water. After final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of a test culture containing 5 × 10 ³ CFU of E. coli, inhibits bacterial growth for 10 days.

Example 8

In accordance with the above method, a reverse osmosis cellulose acetate membrane is formed by dissolving (parts by weight): cellulose acetate (15) in a mixture of acetic acid (10), acetone (10) and water (5), followed by treatment with a precipitant - a mixture of water (95) and acetic acid (5). The reverse osmosis cellulose acetate membrane is placed for 10 seconds in a solution consisting of a mixture containing (parts by weight): 10 formic acid, 10 silver bromide (insoluble in water), 80 water. Then the treated membrane is dried at a temperature of 95 ° C, washed in running water. After the final drying, a polymer antibacterial membrane is obtained, which, after filtering a suspension of Test culture containing 5 × 10 ³ CFU of E. coli, inhibits growth for 14 days.

Example 9 (comparative in accordance with the prototype)

In accordance with the decision of the prototype received microfiltration polymer membrane by preparing a solution based on polyethersulfone and the subsequent) on the introduction of silver nanoparticles with a size of 8 nm in an amount of 0.2% of the mass. in relation to polyethersulfone. After drying, a polymer antibacterial membrane is obtained: after filtering a suspension of the test culture containing 5 × 10 ³ CFU of E. coli, it inhibits the growth of bacteria for 6 days.

Bibliographic data

1. Silver nanoparticles as antimicrobial agents, publ. in Colloid and Interface Science in 2004 (275, 177-182).

2. Polysulfone ultrafiltration membranes impregnated with silver nanoparticles to remove viruses with high resistance to bio-pollution, publ. in the "Water Research / Journal of the International Water Association" in 2009 (No. 43 pp. 715-723).

3. Silver with delivery to the cage (publ. On the website of the company ARGO argonet.ru).

4. Application for US patent No. 201110024355 (published in 2011).

5. Korean patent application No. 20070071766 (publ. 2007).

Claims (1)

A method of producing an antibacterial polymer membrane, comprising preparing a polymer solution, treating with an antibacterial substance, molding the polymer membrane and drying, characterized in that the membrane is treated with an antibacterial substance after the membrane is formed, after which additional drying, washing with water and final drying are carried out, wherein as antibacterial substance uses the following composition, parts by weight:
Silver salt, sparingly or insoluble 5-10 Formic acid 2-25 Water 65-93