KR0170072B1 - Method for manufacturing polyamide nano composite membrane - Google Patents

Abstract

The present invention relates to a nano composite membrane which can separate various impurities present in a liquid and effectively obtain water suitable for drinking or industrial water, and does not require an excellent salt rejection ratio such as a reverse osmosis composite membrane. The aim is to obtain a nanocomposite membrane which is effectively used in the field of obtaining more permeate water at a lower pressure than the reverse osmosis composite membrane, and the technical composition is to apply the polyfunctional amine solution to the surface of the microporous substrate and to dry the surface. In the preparation of the crosslinked polypiperazine amide nanocomposite membrane obtained by interfacial polymerization with a polyfunctional acid halide compound solution, the polyfunctional amine mixed solution is 0 to 75% by weight of piperazine and 25 to 100% by weight of meta-phenylenediamine. %, And the composition of the polyfunctional acid halide compound solution is 0.01-1% As a method for producing a polyamide-based nanocomposite membrane characterized in that it has an interfacial polymerization to have a rate, the nanocomposite membrane according to the present invention can be made by adjusting the salt excretion rate and permeate amount according to the use, and thus it is more widely used than the conventional method. There is an advantage to use.

Description

Manufacturing Method of Polyamide Nanocomposite Membrane

The present invention relates to a nano composite membrane (NANO COMPOSITE MEMBRANE) that can effectively separate the various components present in the liquid to obtain water suitable for drinking or industrial water, and more particularly, to apply the amine mixed solution to the surface of the microporous substrate. The present invention relates to a crosslinked polypiperazinamide nanocomposite membrane obtained by interfacial polymerization of a polyfunctional acid halogen compound solution after drying the surface.

Nanocomposite membranes do not require the same high rejection coefficients as reverse osmosis composite membranes, and are intended to achieve higher permeability at lower pressures than reverse osmosis composite membranes, ie softening soft water, purification of pharmaceuticals, and Effective for separation and food manufacturing processes, the main separation targets of nanocomposite membranes are divalent ions having a solute size slightly larger than 10 microns, i.e. nanometers (nm), various monosaccharides and low molecular weight organic matter.

Therefore, the nanocomposite membrane has a filtration range between the reverse osmosis membrane and the ultrafiltration membrane. The nanocomposite membrane shows excellent selective separation ability in the special processing, antibiotic separation, and monosaccharide separation in the dairy industry such as water or milk with low pollution. Of course, reverse osmosis membranes can also separate these materials, but the selective separation ability of the nanometer-grade solutes has the disadvantage that they must be operated at a higher pressure than the nanomembrane. Nanomembrane is a hot spot recently because it can separate more material at lower pressure than reverse osmosis membrane.

In the early 1960s, the first reverse osmosis membrane, an asymmetric cellulose diacetate membrane, was developed. The cellulose diacetate membrane has the advantage of being inexpensive. However, it is vulnerable to microorganisms and easily hydrolyzed under strong bases. The disadvantage was narrow range. Since then, studies have been actively conducted on polyamides, polyurethanes, aromatic polysulfones, aromatic polyamides, and the like to compensate for the disadvantages of the cellulose acetate film. Currently, among these, a composite membrane having an aromatic polysulfone as a porous support membrane and a polyamide support layer has been developed and commercialized. That is, the composite membrane is composed of a support layer for maintaining mechanical strength and an active layer having selective permeability, and the manufacturing method of the composite membrane is thin layer dispersion method, immersion coating method, vapor deposition method, Langmuir-Blodgett method, interface. The polymerization method and the like are known. In particular, the nano-membrane or reverse osmosis composite membrane is mainly used in the interfacial polymerization method known by US Patent No. 4,277,344. Such a composite membrane by the interfacial polymerization method is initially used in a porous polysulfone support. It was prepared by reacting an aqueous solution with toluene diisocyanate in hexane (North Star Research, Inc., trade name: NS100). Then, a composite membrane was developed by interfacial polymerization of various characteristics using various aliphatic amines and aromatic amines. It became. However, these composite membranes did not meet expectations in terms of rejection rate and permeation rate, but the composite membrane by interfacial polymerization reached the completion stage as NS300 with the polypiperazinamide active layer was released.

At the time of the development of NS-300, polypiperazineamides had a high exclusion rate of more than 95% for divalent ions and monosaccharides and a relatively wide range of exclusion ratios of 40-96% for sodium chloride were developed. It was obtained by impregnating a polyfunctional amine solution in which piperazine and an alkaline catalyst were mixed on a polysulfone microporous substrate and interfacially polymerizing the polyfunctional acid halogen compound thereon. The exclusion rate of the composite membrane is adjusted by mixing terephthaloyl chloride, isophthaloyl chloride, and trimesoyl chloride in an appropriate ratio as an acid halogen compound. US Pat. No. 4,259,183 of the method for preparing nanocomposite membranes uses piperazine and N, N'-dimethylpiperazine, sodium hydroxide as a catalyst, and interfacial polymerization by mixing isophthaloyl chloride and trimesoyl chloride. A method of using n-nucleic acid as a solvent of a halogen compound has been disclosed. On the other hand, U.S. Patent No. 4,619,767 first coats polyvinyl alcohol on polysulfone, and then interfacially polymerizes with a mixture of diamine and trimesoyl chloride / isophthalaroyl chloride containing piperazine or piperazine structure and n-nucleic acid as a solvent. A method of using is disclosed.

It is an object of the present invention to obtain more permeated water at a lower pressure than reverse osmosis composite membranes without requiring a high rejection rate such as reverse osmosis composite membranes, that is, to separate water of low pollutant antibiotics, to separate monosaccharides, and the like. The present invention provides a method for producing a nanocomposite membrane suitable for separating a solute having a nanometer size.

Particularly, in the present invention, piperazine and meta-phenylenediamine are mixed as diamines, and the flow rate enhancer is also mixed with polyvinyl alcohol to interfacially polymerize with trimezoyl chloride to form an active layer. I can regulate it.

Hereinafter, the present invention will be described in more detail.

The nanoporous membrane is prepared by applying a polyfunctional amine solution to the surface of the microsaccharides obtained by dipping a microporous nonwoven fabric in an amine mixture solution, drying the mixture, and then interfacially polymerizing the polyfunctional acid halide compound solution.

The microporous substrate is a conventional reinforced polysulfone microporous nonwoven fabric, and the polyfunctional amine solution is composed of 0 to 75% by weight of piperazine and 25 to 100% by weight of metaphenylenediamine. The amine mixed solution contains polyvinyl alcohol and sodium hydroxide or N, N'-dimethylpiperazine as an additive in addition to the polyfunctional amine solution.

Polyvinyl alcohol is a flow rate enhancer, and sodium hydroxide, N, N'-dimethylpiperazine is different in the reactivity between aromatic amine and piperazine. So, sodium hydroxide or N, N'-dimethylpiperazine, which is an alkaline catalyst, is added to the active layer. Adjust the structure.

If the content of piperazine exceeds 75% by weight, there is a disadvantage in that the salt excretion falls rapidly, and if the content of metaphenylenediamine is less than 25% by weight, there is a disadvantage in that the permeation amount is lowered.

The polyvinyl alcohol preferably has a molecular weight (Mw) of 5,000 to 100,000 and a degree of hydrolysis of 88 to 99%, and preferably 1 to 10% based on the total amount of the polyfunctional amine solution. If the addition amount is less than 1%, there is a disadvantage in that the hydrolysis under a strong base is easy to narrow the range of use temperature and pH, and if it exceeds 10%, there is a disadvantage in decreasing the water permeability. Moreover, it is ideal to add 0.05-5 weight% of catalysts to a polyfunctional amine solution with respect to the total amount of a polyfunctional amine solution. In addition, since the amine immersion time in the continuous process can be greatly reduced by using ultrasonic waves, the production of nanocomposite membranes can be increased by using ultrasonic waves when the microporous substrate is immersed in the amine mixture solution. In addition, by using ultrasonic waves, polyvinyl alcohol containing amine can be more uniformly and quickly penetrated into the polysulfone porous layer.

The polyfunctional acid halogen compound may be used by mixing one or more of 0.01 to 1.0% by weight in conventional isophthaloyl chloride, trimesoyl chloride and terephthaloyl chloride.

As a solvent of the polyfunctional acid halogen compound, structural isomers of 5 to 12 carbon atoms of n-alkane and 8 saturated or unsaturated hydrocarbons are mixed or used, or 5 to 7 ring hydrocarbons are used. In addition, since the aromatic amine and piperazine have a difference in reactivity, the structure of the active layer is controlled by adding sodium hydroxide or N, N-dimethylpiperazine which is an alkaline catalyst.

The performance of the composite membrane prepared in this manner was evaluated by measuring the salt excretion rate and the permeate amount of magnesium sulfate (MgSO ₄ ) and sodium chloride (NaCl) in a concentration of 500 ppm at 25 ℃, 50 psig. The salt exclusion rate is calculated by the following equation.

Salt Exclusion Rate (%) = (1-Cp / C _F ) × 100

Here, Cp is the concentration of the solute in the feed water, and C _F is the concentration of the solute in the permeate.

Hereinafter, the present invention will be described in more detail based on examples.

[Examples 1-3]

A 25% by weight solution of N-methyl-2-pyrrolidone, polysulfone, and 10% by weight polypyrrolidone was cast on a polyester nonwoven fabric to a thickness of about 150 μm, and immediately immersed in a distilled water bath at 5 ° C. to solidify. Subsequently, the nonwoven fabric-reinforced polysulfone microporous substrate was sufficiently washed with water to replace the solvent and water in the substrate, and then stored in pure water. The polysulfone microporous substrate thus obtained was immersed for 10 seconds by ultrasonic wave in a solution in which 1% by weight of polyvinyl alcohol and 0.1% by weight of N, N-dimethylpiperazine were added to an amine mixture solution having the composition shown in Table 1, and then 0.5% by weight. The solution was impregnated for 3 min in% trimezoyl chloride n-hexane solution. The total amine is 3% by weight in total. The composite membrane thus prepared was dried at 120'c for 5 minutes, washed with 60'c weak alkaline aqueous solution, and then immersed in ethane for 24 hours to remove remaining unreacted amine and polyvinyl alcohol. Table 1 shows the measurement results of the physical properties. Table 1

Comparative Example 1-3

On a polyester nonwoven fabric, a 25% by weight solution of N-methyl-2-pyridone, polysulfone and 10% by weight polypyrrolidone was cast to a thickness of about 150 m and immediately immersed in a distilled water bath at 5'c to solidify. After the nonwoven fabric-reinforced polysulfone microporous substrate was washed with water sufficiently to replace the solvent and water in the substrate, it was stored in pure water. The polysulfone microporous substrate thus obtained was immersed for 5 minutes in a solution in which 1% by weight of polyvinyl alcohol and 0.1% by weight of N, N-dimethylpiperazine were added to an amine mixture solution having the composition shown in Table 2, followed by 0.5% by weight of tri The mesoyl chloride n-hexane solution was impregnated for 3 minutes. The total amine is 3% by weight in total. The composite membrane thus prepared was dried at 120 ° C. for 5 minutes, washed with 60 ° C. weak alkaline solution, and then immersed in ethanol for 24 hours to remove remaining unreacted amine and polyvinyl alcohol. Table 2 shows the measurement results of the physical properties.

EXAMPLES 4-8

A 15% by weight solution of dimethylacetamide, polysulfone and 10% by weight of polypyrrolidone was cast on the polyester nonwoven fabric to a thickness of about 200 μm, immediately immersed in a distilled water bath at a temperature of 5 ° C., and solidified. The porous substrate was washed with water sufficiently to replace the solvent and water in the substrate, and then stored in pure water. The polysulfone microporous substrate thus obtained was added to 2% by weight of piperazine and 1% by weight of polyvinyl alcohol and 0.1% by weight of N, N-dimethylpiperazine in the presence of ultrasonic waves (ultrasound conditions) described in Table 3 below. After immersion in time, the solution was impregnated with 0.5 wt% trimezoyl chloride n-hexane solution for 3 minutes. The composite membrane thus prepared was dried at 100 ° C. for 5 minutes, washed with 60 ° C. weak alkaline solution, and then immersed in ethanol for 24 hours to remove remaining unreacted amine and polyvinyl alcohol. Table 3 shows the measurement results of the physical properties.

[Comparative Examples 4-8]

A 15% by weight solution of dimethylacetamide, polysulfone and 10% by weight of polypyrrolidone was cast on the polyester nonwoven fabric to a thickness of about 200 μm, immediately immersed in a distilled water bath at a temperature of 5 ° C., and solidified. The porous substrate was washed with water sufficiently to replace the solvent and water in the substrate, and then stored in pure water. The polysulfone microporous substrate thus obtained was immersed in a solution in which 1% by weight of polyvinyl alcohol and 0.1% by weight of N, N-dimethylpiperazine were added to 2% by weight of piperazine, and 0.5% by weight after immersion at the time shown in Table 4 below. The trimezoyl chloride n-hexane solution was impregnated for 3 minutes. The composite membrane thus prepared was dried at 100 ° C. for 5 minutes, washed with 60 ° C. weak alkaline solution, and then immersed in ethanol for 24 hours to remove remaining unreacted amine and polyvinyl alcohol. Table 4 shows the measurement results of the physical properties.

Nanocomposite membrane prepared by the present invention can be made by adjusting the salt excretion rate and water permeability according to the use can be used for a wider range of applications than conventional methods.

Claims (2)

In preparing a crosslinked polyamide-based nanocomposite membrane obtained by applying a polyfunctional amine solution to the surface of a microporous substrate, drying the surface, and then interfacially polymerizing the solution with a polyfunctional acid halogen compound, the polyfunctional amine solution is 0.1 to 75 weight of piperazine. %, 25% to 99% by weight of metaphenylenediamine, and the solution of the polyfunctional acid halogen compound is 0.05 to 1% by weight of the trimezoyl chloride solution, and the polyvinyl alcohol is added to the polyfunctional amine solution as the flow increasing agent. When ˜10 wt% is added and the porous support is immersed in the polyfunctional amine solution, the polyvinyl alcohol and the polyfunctional amine are uniformly dispersed on the porous support and distributed well on the surface of the porous support by immersion for 1 to 30 seconds in the presence of ultrasonic waves by an ultrasonic resonator. After drying, the surface is dried and soaked in the polyfunctional acid halogen compound solution for 30 seconds to 2 minutes. Surface and method of manufacturing the flow polyamide-based nano-composite membrane, characterized in that a polymerization reaction to take place. The method of manufacturing a nanocomposite membrane according to claim 1, wherein the frequency of the ultrasonic resonator is 10 to 50 kHz.