CN104028120A - Method for preparing carboxymethylcellulose sodium composite-filled polyamide nanofiltration membrane - Google Patents

Abstract

The invention discloses a preparation method of polyamide nanofiltration membrane filled with sodium carboxymethyl cellulose compound. The sodium carboxymethyl cellulose complex was prepared by ion cross-linking, and it was added to the aqueous monomer solution of the synthetic polyamide membrane, and the sodium carboxymethyl cellulose complex was prepared by interfacial polymerization to fill the polyamide nanofiltration membrane . Utilizing the good hydrophilicity, chargeability and unique nano-pore structure of the composite, the water permeation flux of the membrane is greatly improved while maintaining the high selectivity of the polyamide membrane to inorganic salts. Under the operating pressure of 0.6MPa, the nanofiltration membrane has a water flux of 50-65L.m ^-2 .h ^-1 and has a high rejection rate for divalent ions, up to 97%. The rejection rate is generally less than 25%. Therefore, the prepared polyamide nanofiltration membrane filled with sodium carboxymethylcellulose composite has high separation selectivity and water permeation flux, and the membrane preparation method is simple and easy, with low cost, and has good industrial application prospects.

Description

Preparation method of carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane

technical field

The invention belongs to the field of nanofiltration membrane separation, and in particular relates to a preparation method of polyamide nanofiltration membrane filled with sodium carboxymethyl cellulose compound.

Background technique

As a new separation technology, nanofiltration has the advantages of low energy consumption, high separation efficiency, and environmental protection compared with traditional separation technologies such as distillation and rectification. Nanofiltration membrane is a new type of pressure-driven separation membrane with a pore size between ultrafiltration membrane and reverse osmosis membrane. According to the principles of electrostatic repulsion and pore size sieving, nanofiltration membranes can intercept high-valence ions and organic macromolecules, while allowing low-valence ions and small organic molecules to pass through. And the separation of organic substances with different molecular weights has been gradually used in water softening, wastewater treatment, concentration and separation of substances in food, chemical, pharmaceutical and other fields.

At present, commercial nanofiltration membranes are mainly prepared by the interfacial polymerization method, which generally uses polyamines in the aqueous phase and polyacyl chloride monomers in the organic phase to polymerize at the interface of the two phases to form a dense polyamide skin layer (US Patent 5,693,227; US Patent 5,152,901; US Patent 4,769,148). Although polyamide nanofiltration membranes have high salt rejection and water flux, in order to further reduce the operating cost of the nanofiltration separation process, improving the water flux and separation performance of the membrane is the eternal theme of the development of nanofiltration membranes. According to existing reports, some polymer materials (PVA, PEG) with hydrophilicity and fouling resistance are introduced into the polyamide membrane in situ to adjust the composition and structure of the membrane, and improve the separation performance and fouling resistance of the membrane (Macromol. Chem. Phys., 2005, 206: 1934-1940; Polymer, 2007, 48: 1165–1170; J. Membr. Sci., 2011, 367: 158-165). In addition, there are also inorganic nanomaterials such as zeolite, nano-silica, and carbon nanotubes introduced into polyamide nanofiltration membranes to improve their water permeability and pollution resistance (J. Membr. Sci., 2007, 294: 1-7 ; Desalination, 2008, 219: 48–56). However, according to the existing reports, these modified materials still have problems such as ineffective modification, high manufacturing cost of nanomaterials, easy aggregation in the membrane, and defects in the membrane. Therefore, it is very necessary to develop some new modified materials to improve and enhance the performance of polyamide nanofiltration membranes.

Polyelectrolyte complexes are a class of multi-component polymer materials formed by the combination of oppositely charged polyelectrolyte molecular chains with each other through electrostatic force. widely used. In recent years, we have successfully prepared water-dispersible polyelectrolyte composites by ion cross-linking method, and successfully used them in the preparation of pervaporation membranes (J. Membr. Sci., 2009, 329: 175–182; J. Membr. Sci., 2009, 333: 68–78). The study found that the polyelectrolyte complex contains a large number of ion-pair cross-linked structures inside and a certain amount of free charged groups on the surface, and its pervaporation membrane has high separation factor and permeation flux at the same time. For example, if the polyelectrolyte complex is introduced into the polyamide nanofiltration membrane, it can not only take advantage of its good hydrophilicity and chargeability, but also rely on its unique nanopore structure, while maintaining the good separation selectivity of the membrane, The water permeability of the membrane is greatly improved, so that it can better meet the needs of practical applications.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a preparation method of sodium carboxymethylcellulose composite filled polyamide nanofiltration membrane.

The preparation method of sodium carboxymethyl cellulose composite filled polyamide nanofiltration membrane comprises the steps:

(1) Dissolve 1-3 parts by mass of sodium carboxymethylcellulose and 0.5-2 parts by mass of cationic polyelectrolyte in 100-500 parts by mass of acidic aqueous solution, and then add the above-mentioned acidic aqueous solution of cationic polyelectrolyte to carry out ionic cross-linking in acidic aqueous solution of sodium carboxymethyl cellulose, precipitate with deionized water for many times, wash and dry to obtain sodium carboxymethyl cellulose complex; ~500 parts by mass of alkaline aqueous solution to form a composite dispersion;

(2) Dissolve the polyamine monomer in water, then add the compound dispersion and sodium hydroxide solid to make an aqueous phase solution; dissolve the polyacyl chloride monomer in an organic solvent to make an organic phase solution;

(3) Immerse the porous polysulfone support membrane in the aqueous phase solution for 1 to 4 minutes, take out and remove the excess aqueous phase solution on the surface; then immerse in the organic phase solution for 0.5 to 2 minutes, take out and remove the residual organic phase on the surface solution; solidify at 45-75 ^o C for 15-35 minutes, rinse with deionized water, and obtain polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite;

The cationic polyelectrolyte described in step 1) is polydimethyldiallylammonium chloride, polymethacryloxyethyltrimethylammonium chloride, quaternized polyvinylpyridine or cationic cellulose; The polyamine monomer described in step 2) is piperazine, m-phenylenediamine or 1, 3, 5-triaminobenzene; the polyacyl chloride monomer described in step 2) is phthaloyl chloride, m-phenylene Diformyl chloride, terephthaloyl chloride, trimesoyl chloride or biphenyl tetracarbonyl chloride; the acidic aqueous solution described in step 1) is hydrochloric acid, acetic acid or sulfuric acid aqueous solution with a concentration of 0.01-0.1% by mass; step 1) The drying condition described in is to heat at 40-60 ^o C for 8-16 hours; the alkaline aqueous solution described in step 1) is an aqueous solution of sodium hydroxide or potassium hydroxide with a concentration of 0.1-0.5% by mass; the step 2) The mass percentage concentration of the polyamine monomer in the aqueous phase solution described in step 2) is 0.2-3%; the mass percentage concentration of the compound in the aqueous phase solution described in step 2) is 0.01-0.5%; step 2) The mass percent concentration of sodium hydroxide in the aqueous phase solution described in is 0.01 to 0.2%; the mass percent concentration of the polyacyl chloride monomer in the organic phase solution described in step 2) is 0.1 to 1%; in step 2) The solvent of the organic phase solution is n-hexane, cyclohexane or heptane.

The polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite can be used in the fields of seawater desalination, hard water softening, separation of inorganic salts in different valence states, and separation of inorganic salts and organic matter.

The separation performance test method of a kind of sodium carboxymethyl cellulose composite filled polyamide nanofiltration membrane of the present invention is as follows: the nanofiltration membrane is placed in the conventional nanofiltration testing device in this field, and the membrane is pre-heated under 0.7 MPa operating pressure before testing. Then, under the test conditions of 25 ^o C and 0.6 MPa, the water permeation flux (J) and the material rejection rate (R) of the membrane were measured. The calculation formula is as follows: J=V/(At ); R=1-C _p ⁄C _f ; Among them, V-the volume of the feed liquid passing through the membrane, A-the effective area of the membrane is 22.4 cm ² , t-running time, C _p -permeate concentration, C _f - The concentration of the feed solution; the concentration of the inorganic salt solution is obtained by measuring the conductivity value.

The sodium carboxymethyl cellulose compound has good hydrophilicity, chargeability and special nano-pore structure, adding it to the polyamide nanofiltration membrane can improve the hydrophilicity of the membrane and the retention of water molecules in the membrane. Transmission efficiency, which increases the water permeate flux of the membrane while maintaining high salt separation efficiency. In the present invention, by adjusting the chemical structure and film-forming conditions of the sodium carboxymethyl cellulose compound, the polyamide nanofiltration membrane filled with the sodium carboxymethyl cellulose compound has a retention rate of up to ₉₇ % for divalent salt _Na2SO4 , while the rejection rate to monovalent salt NaCl is lower than 25%, and the water flux is higher than 50 Lm ^-2 .h ^-1 ; in addition, the functional material sodium carboxymethyl cellulose used to prepare polyamide nanofiltration membrane in the present invention The complex can be prepared by a simple water-phase ion cross-linking method, and the raw materials selected for interfacial polymerization to form a film are commercially available chemical reagents commonly used in this field. Therefore, the raw materials used in the present invention are convenient and easy to obtain, the preparation process of the membrane is simple, the production cost is low, the performance of the membrane is excellent, and the membrane has good industrial applicability.

Description of drawings:

Fig. 1 is the infrared spectrum of the sodium carboxymethyl cellulose compound of the present invention;

Fig. 2 is the surface morphology figure of polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite according to the present invention.

Detailed ways

The preparation method of sodium carboxymethyl cellulose composite filled polyamide nanofiltration membrane comprises the steps:

(1) Dissolve 1-3 parts by mass of sodium carboxymethylcellulose and 0.5-2 parts by mass of cationic polyelectrolyte in 100-500 parts by mass of acidic aqueous solution, and then add the above-mentioned acidic aqueous solution of cationic polyelectrolyte to carry out ionic cross-linking in acidic aqueous solution of sodium carboxymethyl cellulose, precipitate with deionized water for many times, wash and dry to obtain sodium carboxymethyl cellulose complex; ~500 parts by mass of alkaline aqueous solution to form a composite dispersion;

(2) Dissolve the polyamine monomer in water, then add the compound dispersion and sodium hydroxide solid to make an aqueous phase solution; dissolve the polyacyl chloride monomer in an organic solvent to make an organic phase solution;

(3) Immerse the porous polysulfone support membrane in the aqueous phase solution for 1 to 4 minutes, take out and remove the excess aqueous phase solution on the surface; then immerse in the organic phase solution for 0.5 to 2 minutes, take out and remove the residual organic phase on the surface solution; solidify at 45-75 ^o C for 15-35 minutes, rinse with deionized water, and obtain polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite;

The cationic polyelectrolyte described in step 1) is polydimethyldiallylammonium chloride, polymethacryloxyethyltrimethylammonium chloride, quaternized polyvinylpyridine or cationic cellulose; The polyamine monomer described in step 2) is piperazine, m-phenylenediamine or 1, 3, 5-triaminobenzene; the polyacyl chloride monomer described in step 2) is phthaloyl chloride, m-phenylene Diformyl chloride, terephthaloyl chloride, trimesoyl chloride or biphenyl tetracarbonyl chloride; the acidic aqueous solution described in step 1) is hydrochloric acid, acetic acid or sulfuric acid aqueous solution with a concentration of 0.01-0.1% by mass; step 1) The drying condition described in is to heat at 40-60 ^o C for 8-16 hours; the alkaline aqueous solution described in step 1) is an aqueous solution of sodium hydroxide or potassium hydroxide with a concentration of 0.1-0.5% by mass; the step 2) The mass percentage concentration of the polyamine monomer in the aqueous phase solution described in step 2) is 0.2-3%; the mass percentage concentration of the compound in the aqueous phase solution described in step 2) is 0.01-0.5%; step 2) The mass percent concentration of sodium hydroxide in the aqueous phase solution described in is 0.01 to 0.2%; the mass percent concentration of the polyacyl chloride monomer in the organic phase solution described in step 2) is 0.1 to 1%; in step 2) The solvent of the organic phase solution is n-hexane, cyclohexane or heptane.

Provide the embodiment of the present invention below, but the present invention is not limited by embodiment:

Example 1:

Get 1g sodium carboxymethyl cellulose and 0.5g polydimethyldiallyl ammonium chloride to be dissolved in 100g mass percentage concentration respectively in the hydrochloric acid aqueous solution of 0.01wt%, then above-mentioned polydimethyldiallyl chloride Ammonium chloride acidic aqueous solution was added dropwise to carboxymethylcellulose sodium acidic aqueous solution to carry out ion cross-linking, after several times of deionized water precipitation, washing and drying at 40 ^{o C} for 16 hours, the carboxymethylcellulose sodium complex was obtained; Then add the above 0.1g compound to 100g of sodium hydroxide aqueous solution with a mass percent concentration of 0.1wt% to form a compound dispersion; soak the porous polysulfone support membrane in the aqueous phase solution for 1 minute, and in the aqueous phase solution The concentration of piperazine is 0.2 wt%, the concentration of the compound is 0.01 wt%, the concentration of NaOH is 0.01 wt%, take out and remove the excess aqueous phase solution on the surface; In the n-hexane acid chloride solution, the interfacial polymerization reaction was carried out for 0.5 minutes, solidified at 45 ^o C for 35 minutes, and rinsed with deionized water to obtain the polyamide nanofiltration membrane filled with sodium carboxymethyl cellulose composite.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 21.2 %, the water flux is 50.6Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 94.7%, and the water flux is 49.5Lm ^-2 .h ^-1 .

Example 2:

Get 3 g sodium carboxymethyl cellulose and 2 g polydimethyldiallyl ammonium chloride to be dissolved in 500 g mass percent concentration respectively in the hydrochloric acid aqueous solution of 0.1 wt%, then above-mentioned polydimethyldiallyl The ammonium chloride acidic aqueous solution was added dropwise into the acidic aqueous solution of sodium carboxymethylcellulose for ion cross-linking, after several times of deionized water precipitation, washing and drying at 60 ^oC for 8 hours, the composite sodium carboxymethylcellulose was obtained. Then, the above 0.5 g compound was added to 500 g mass percent concentration of 0.5 wt% sodium hydroxide aqueous solution to form a compound dispersion; the porous polysulfone support membrane was immersed in the aqueous solution for 4 minutes, and the water The concentration of piperazine in the phase solution is 3 wt%, the concentration of the complex is 0.5 wt%, and the concentration of NaOH is 0.2 wt%, take out and remove the excess aqueous phase solution on the surface; In the n-hexane solution of trimesoyl chloride, the interfacial polymerization reaction was carried out for 2 minutes, and solidified at 75 ^o C for 15 minutes. After rinsing with deionized water, the polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite was obtained.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 23.5 %, the water flux is 53.8Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 95.2%, and the water flux is 52.5Lm ^-2 .h ^-1 .

Example 3:

Get 2 g sodium carboxymethyl cellulose and 1 g polydimethyldiallyl ammonium chloride to be dissolved in 500 g mass percentage concentration respectively in the hydrochloric acid aqueous solution of 0.05 wt%, then above-mentioned polydimethyldiallyl Ammonium chloride acidic aqueous solution was added dropwise into carboxymethylcellulose sodium acidic aqueous solution to carry out ionic cross-linking, after several times of deionized water precipitation, washing and drying at 50 ^oC for 12 hours, the compound sodium carboxymethylcellulose was obtained. Then, the above 0.25 g compound was added to 500 g mass percent concentration of 0.25 wt% sodium hydroxide aqueous solution to form a compound dispersion; the porous polysulfone support membrane was immersed in the aqueous phase solution for 2 minutes, and the water The concentration of piperazine in the phase solution is 1 wt%, the concentration of the complex is 0.25 wt%, and the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; In the trimesoyl chloride n-hexane solution, the interfacial polymerization reaction was carried out for 1 minute, solidified at 60 ^o C for 30 minutes, and rinsed with deionized water to obtain the polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite.

Comparative example 1

Referring to the steps in Example 3, without preparing sodium carboxymethylcellulose complex, directly use piperazine and trimesoyl chloride as raw materials (for the addition ratio, refer to Example 3) to prepare polyamide nanofiltration membranes.

Comparative example 2

Referring to the steps of Example 3, sodium carboxymethyl cellulose was added instead of sodium carboxymethyl cellulose compound to the polyamide membrane preparation process (addition ratio refer to Example 3) to prepare a polyamide nanofiltration membrane.

Comparative example 3

Referring to the steps in Example 3, polydimethyldiallyl ammonium chloride was added instead of sodium carboxymethyl cellulose compound to the polyamide membrane preparation process (addition ratio refer to Example 3) to prepare polyamide nanofiltration membrane .

Table 1 embodiment 3, the separation performance comparison of the polyamide membrane prepared by comparative examples 1-3

Na ₂ SO ₄ rejection rate (%) Water flux (Lm ^-2 .h ^-1 ) NaCl rejection rate (%) Water flux (Lm ^-2 .h ^-1 ) Example 3 96.7 63.5 19.8 65.7 Comparative example 1 94.5 28.5 38.7 30.1 Comparative example 2 92.8 35.2 27.5 36.8 Comparative example 3 85.9 37.5 22.8 39.5

The results in Table 1 show that polyamide nanofiltration membranes can be prepared by the four methods, but there are large differences in the rejection rate and water flux of divalent and monovalent salts. The reason is that the additives used to prepare polyamide membranes It is caused by the difference in the microstructure and hydrophilicity of the material.

In Comparative Example 1, no other modified materials were added, and the polyamide film was composed of a rigid cross-linked structure of naphthenes and aromatic hydrocarbons, and the film was relatively dense; in Comparative Example 2, sodium carboxymethyl cellulose was added as the modified material , the polymer material with good flexibility and hydrophilicity is introduced into the polyamide film, so that the compactness of the film is reduced and the hydrophilicity is increased; in comparative example 3, polydimethyldiallylammonium chloride is added as As a modified material, this kind of cationic polyelectrolyte does not participate in the interfacial polymerization reaction, and it cannot exist stably in the polyamide membrane, which will cause defects in the membrane.

In Example 3, the sodium carboxymethyl cellulose compound was used as the modified material, and it was introduced into the polyamide membrane by using its own unique nanostructure and good hydrophilicity, which can not only improve the hydrophilicity of the membrane , can also form a "water channel" structure in the membrane to promote the transfer of water molecules in the membrane; at the same time, due to the good dispersion of the composite particles, it can ensure that the compactness of the membrane is not affected, and has high selective separation. Therefore, the polyamide nanofiltration membrane prepared by using the sodium carboxymethyl cellulose compound as the modified material has high separation selectivity and water permeability.

Example 4:

Get 2.5 g sodium carboxymethyl cellulose and 0.5 g polydimethyldiallyl ammonium chloride and dissolve in 500 g mass percent concentration respectively in the hydrochloric acid aqueous solution of 0.05 wt%, then above-mentioned polydimethyldiallyl Ammonium chloride acidic aqueous solution was added dropwise into carboxymethylcellulose sodium acidic aqueous solution to carry out ionic cross-linking, after several times of deionized water precipitation, washing and drying at 50 ^oC for 12 hours, the compound sodium carboxymethylcellulose was obtained. Then, the above 0.25 g compound was added to 500 g mass percent concentration of 0.25 wt% sodium hydroxide aqueous solution to form a compound dispersion; the porous polysulfone support membrane was immersed in the aqueous phase solution for 2 minutes, and the water The concentration of piperazine in the phase solution is 0.5 wt%, the concentration of the compound is 0.25 wt%, and the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; In the trimesoyl chloride n-hexane solution, the interfacial polymerization reaction was carried out for 1 minute, solidified at 50 ^o C for 30 minutes, and rinsed with deionized water to obtain a polyamide nanofiltration membrane filled with carboxymethylcellulose sodium composite.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 17.5 %, the water flux is 63.8Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 96.2%, and the water flux is 62.5Lm ^-2 .h ^-1 .

Example 5:

Get 2.5 g sodium carboxymethyl cellulose and 0.5 g polymethacryloyloxyethyltrimethylammonium chloride and dissolve in 500 g mass percentage concentration respectively in the hydrochloric acid aqueous solution of 0.05 wt%, then above-mentioned polymethacrylic The acidic aqueous solution of acyloxyethyltrimethylammonium chloride was added dropwise into the acidic aqueous solution of sodium carboxymethylcellulose for ion cross-linking, after several times of deionized water precipitation, washing and drying at 50 ^oC for 12 hours, the carboxy Sodium methylcellulose complex; then add the above 0.25 g of the complex to 500 g of 0.25 wt% sodium hydroxide aqueous solution to form a complex dispersion; the porous polysulfone support membrane in the aqueous phase solution Immerse in water for 2 minutes, the concentration of m-phenylenediamine in the aqueous phase solution is 0.5 wt%, the concentration of the complex is 0.25 wt%, and the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; then immerse in In the n-hexane solution of trimesoyl chloride with a mass percentage concentration of 0.2 wt%, the interfacial polymerization reaction was carried out for 1 minute, cured at 50 ^o C for 30 minutes, and rinsed with deionized water to obtain sodium carboxymethylcellulose composite filled polystyrene. Amide nanofiltration membrane.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 18.3 %, the water flux is 61.5Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 95.8%, and the water flux is 58.2Lm ^-2 .h ^-1 .

Example 6:

Get 2.5 g sodium carboxymethyl cellulose and 0.5 g polydimethyldiallyl ammonium chloride and dissolve in 500 g mass percentage concentration respectively in the acetic acid aqueous solution of 0.05 wt%, then above-mentioned polydimethyldiallyl Ammonium chloride acidic aqueous solution was added dropwise into carboxymethylcellulose sodium acidic aqueous solution to carry out ionic cross-linking, after several times of deionized water precipitation, washing and drying at 50 ^oC for 12 hours, the compound sodium carboxymethylcellulose was obtained. Then, the above 0.25 g compound was added to 500 g mass percentage concentration of 0.25 wt% potassium hydroxide aqueous solution to form a compound dispersion; the porous polysulfone support membrane was immersed in the aqueous phase solution for 2 minutes, and the water The concentration of 1, 3, 5-triaminobenzene in the phase solution is 0.5 wt%, the concentration of the complex is 0.25 wt%, and the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; then immerse into the mass In the phthaloyl chloride cyclohexane solution with a percentage concentration of 0.2 wt%, the interfacial polymerization reaction was carried out for 1 minute, cured at 50 ^o C for 30 minutes, and rinsed with deionized water to obtain sodium carboxymethylcellulose composite filled Polyamide nanofiltration membrane.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 15.6 %, the water flux is 60.4Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 95.6%, and the water flux is 58.5Lm ^-2 .h ^-1 .

Example 7:

Get 2 g of sodium carboxymethyl cellulose and 1 g of quaternized polyvinylpyridine and dissolve them in 500 g of aqueous hydrochloric acid with a mass percent concentration of 0.05 wt%, and then add the above-mentioned quaternized polyvinylpyridine acidic solution dropwise to Carry out ionic cross-linking in the acidic aqueous solution of sodium carboxymethyl cellulose, precipitate with deionized water several times, wash and dry at 50 ^oC for 12 hours to obtain the sodium carboxymethyl cellulose complex; then the above 0.25 g The compound was added to 500 g of sodium hydroxide aqueous solution with a mass percentage concentration of 0.25 wt% to form a compound dispersion; the porous polysulfone support membrane was immersed in the aqueous solution for 2 minutes, and the concentration of piperazine in the aqueous solution was 1 wt%, the concentration of the complex is 0.25 wt%, the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; , interfacial polymerization reaction for 1 minute, solidified at 60 ^o C for 30 minutes, and rinsed with deionized water to obtain polyamide nanofiltration membrane filled with sodium carboxymethyl cellulose composite.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 18.6 %, the water flux is 58.2Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 96.2%, and the water flux is 56.5Lm ^-2 .h ^-1 .

Example 8:

Get 2 g of sodium carboxymethyl cellulose and 1 g of cationic cellulose and dissolve them in 500 g of aqueous hydrochloric acid with a mass percent concentration of 0.05 wt%, and then add the above-mentioned acidic solution of cationic cellulose to the acidic solution of sodium carboxymethyl cellulose. Carry out ionic cross-linking in aqueous solution, precipitate with deionized water several times, wash and dry at 50 ^oC for 12 hours to obtain sodium carboxymethyl cellulose complex; then add 0.25 g of the above complex to 500 g mass percent Concentration is 0.25 wt% sodium hydroxide aqueous solution to prepare composite dispersion; the porous polysulfone support membrane is immersed in the aqueous phase solution for 2 minutes, the concentration of piperazine in the aqueous phase solution is 1 wt%, the concentration of the composite The concentration of NaOH is 0.25 wt%, and the concentration of NaOH is 0.1 wt%, take out and remove the excess aqueous phase solution on the surface; then immerse in the trimesoyl chloride-n-hexane solution with a mass percentage concentration of 0.5 wt%, and perform interfacial polymerization reaction for 1 minute. After solidification at 60 ^o C for 30 minutes and rinsing with deionized water, a polyamide nanofiltration membrane filled with sodium carboxymethyl cellulose composite was obtained.

Carboxymethylcellulose sodium composite filled polyamide nanofiltration membrane at 25 ^o C, 0.6MPa pressure, for the separation of 1g.L ^-1 NaCl and Na ₂ SO ₄ solution: the rejection rate of NaCl is 20.6 %, the water flux is 63.5Lm ^-2 .h ^-1 ; the rejection rate of Na ₂ SO ₄ is 96.8%, and the water flux is 62.5Lm ^-2 .h ^-1 .

Claims (9)

1. sodium carboxymethylcellulose compound is filled a preparation method for polyamide nanofiltration membrane, it is characterized in that comprising the steps:

(1) cationic polyelectrolyte of the sodium carboxymethylcellulose of 1～3 mass parts and 0.5～2 mass parts is dissolved in respectively in the acidic aqueous solution of 100～500 mass parts, again above-mentioned cationic polyelectrolyte acidic aqueous solution is added drop-wise to and in sodium carboxymethylcellulose acidic aqueous solution, carries out ionomer, through the precipitation of deionized water repeatedly, washing, obtain sodium carboxymethylcellulose compound after dry; Then the sodium carboxymethylcellulose compound of above-mentioned 0.1～0.5 mass parts is joined in the alkaline aqueous solution of 100～500 mass parts and be made into compound dispersion liquid;

(2) polyamine monomer is dissolved in the water, then adds compound dispersion liquid and sodium hydrate solid, be made into aqueous phase solution; Polynary acyl chlorides monomer is dissolved in organic solvent, is made into organic phase solution;

(3) porous polysulfones support membrane is flooded 1～4 minute in aqueous phase solution, take out and remove the excessive aqueous phase solution in surface; Be immersed in again in organic phase solution 0.5～2 minute, take out and remove the remaining organic phase solution in surface; 45～75 ^ounder C, solidify 15～35 minutes, after rinsed with deionized water, obtain sodium carboxymethylcellulose compound and fill polyamide nanofiltration membrane;

Cationic polyelectrolyte described in step 1) is PDDA, polymethyl acyl-oxygen ethyl-trimethyl salmiac, quaternized polyvinylpyridine or cationic cellulose;

Step 2) the polyamine monomer described in is piperazine, m-phenylene diamine (MPD) or 1,3,5-triaminobenzene;

Step 2) the polynary acyl chlorides monomer described in is o-phthaloyl chloride, m-phthaloyl chloride, paraphthaloyl chloride, pyromellitic trimethylsilyl chloride or biphenyl tetracarboxylic acyl chlorides.

2. preparation method as claimed in claim 1, is characterized in that the acidic aqueous solution described in step 1) is that mass percent concentration is 0.01～0.1% hydrochloric acid, acetic acid or aqueous sulfuric acid.

3. preparation method as claimed in claim 1, is characterized in that the drying condition described in step 1) is 40～60 ^ounder C, heat 8～16 hours.

4. preparation method as claimed in claim 1, is characterized in that the alkaline aqueous solution described in step 1) is that mass percent concentration is 0.1～0.5% NaOH or potassium hydroxide aqueous solution.

5. preparation method as claimed in claim 1, is characterized in that step 2) described in aqueous phase solution in the mass percent concentration of polyamine monomer be 0.2～3%.

6. preparation method as claimed in claim 1, is characterized in that step 2) described in aqueous phase solution in the mass percent concentration of compound be 0.01～0.5 %.

7. preparation method as claimed in claim 1, is characterized in that step 2) described in aqueous phase solution in the mass percent concentration of NaOH be 0.01～0.2%.

8. preparation method as claimed in claim 1, is characterized in that step 2) described in organic phase solution in the mass percent concentration of polynary acyl chlorides monomer be 0.1～1%.

9. preparation method as claimed in claim 1, is characterized in that step 2) described in the solvent of organic phase solution be n-hexane, cyclohexane or heptane.