CN105457506A - Anti-oxidation ultrafiltration membrane and preparation method thereof - Google Patents

Abstract

The invention discloses an anti-oxidation ultrafiltration membrane and a preparation method thereof and belongs to the field of material preparation. The anti-oxidation ultrafiltration membrane is prepared from, by mass, 100 parts of PVDF powder, 40-60 parts of a solvent and 0.5-1 part of an anti-oxidation agent. The anti-oxidation agent is obtained through a reaction of dendritic polyethylene imine, long-chain alkyl amine substance and a phenol or ester compound. The long-chain alkyl amine substance in the anti-oxidation ultrafiltration membrane can neutralize and adsorb HC1 released in the PVDF decomposition process, and carries out an addition reaction with double bonds formed through PVDF decomposition, and therefore the anti-oxidation performance of PVDF materials is improved.

Description

A kind of anti-oxidation ultrafiltration membrane and preparation method thereof

technical field

The invention belongs to the field of material preparation, and more specifically relates to an oxidation-resistant ultrafiltration membrane and a preparation method thereof.

Background technique

Currently, the most widely used ultrafiltration membrane is made of PVDF. The traditional membrane material industry is improving the hydrophilicity and high flux of the membrane. However, with the increasing water quality requirements and the proportion of reused water, physical and chemical pretreatment methods such as oxidation are also continuously strengthened, resulting in the requirement for oxidation resistance of ultrafiltration membranes. Also getting higher and higher.

At present, there are existing literature and patent reports that the purpose of improving the oxidation resistance of the membrane is achieved by adding oxidation-resistant materials to the PVDF material. For example, the Chinese patent application number is CN201310097069, and the patent application document with the application publication date of March 25, 2013 discloses a doped polyvinyl formal layer and polypropylene phthalate layer to improve the resistance of the film material. Oxidizing properties. The Chinese patent application number is CN200910220545, and the patent application document (publication number CN101721927B) with the application publication date of December 1, 2009 discloses a doped phthalazinone structure copolymerized polyarylethersulfone to improve the oxidation resistance of the membrane material. The Chinese patent application number is CN200510011473, and the patent application document (publication number CN1695778B) with the application publication date of March 25, 2005 discloses a doped polyarylethersulfone or polyaryletherketone to improve the oxidation resistance of the membrane material.

However, the method of preparing oxidation-resistant ultrafiltration membranes by doping dendritic polyethyleneimine, long-chain alkylamines, and phenols or esters in PVDF has not been reported.

Contents of the invention

1. The problem to be solved

Aiming at the problem that the existing ultrafiltration membrane is easily oxidized during use in highly oxidative water bodies, the invention provides an oxidation-resistant ultrafiltration membrane and a preparation method thereof.

2. Technical solution

In order to solve the problems in the prior art, the main components of the raw material of the ultrafiltration membrane prepared by the present invention include PVDF powder, solvent and anti-oxidant, specifically, the technical scheme of the present invention is as follows:

An oxidation-resistant ultrafiltration membrane, the main components of the raw materials for preparing the oxidation-resistant ultrafiltration membrane and the parts by weight of each main component are: PVDF powder: 100 parts; solvent: 40-60 parts; oxidation resistance: 0.5 -1 copy.

Preferably, the solvent is one or more of dimethylacetamide, dimethylformamide, dimethylsulfoxide or N-methylpyrrolidone.

Preferably, the oxidation resistance is formed by cross-linking and copolymerizing monomer A, monomer B and monomer C, wherein monomer A is dendritic polyethyleneimine; monomer B is a long-chain alkylamine; Monomer C is a phenolic or ester compound.

Preferably, the structural formula of the dendritic polyethyleneimine is:

Wherein, n is 100-1000, and the molecular weight of dendritic polyethyleneimine is 50000-500000.

Preferably, the structural formula of the long-chain alkylamines is:

In the formula, m is 10-12, R is methyl or ethyl, and X is a halogen element.

Preferably, the long-chain alkylamines are dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyldimethylethylammonium bromide, One or more of tetraalkyldimethylethylammonium bromide, tetradecyldimethylethylammonium chloride, tridecyltrimethylammonium bromide, etc.; the monomer C It is one of butyl hydroxyanisole, tetraerythritol ester and tert-butyl hydroquinone.

The above-mentioned preparation method of an oxidation-resistant ultrafiltration membrane, the specific preparation steps are:

(1) react monomer A, monomer B and monomer C in proportion to prepare oxidation resistance;

(2) Dissolve PVDF powder in a solvent in proportion, add anti-oxidant, stir evenly, after defoaming and curing, use the traditional phase transformation method to stand, gel, and scrape the casting liquid to synthesize polyvinylidene fluoride Ethylene ultrafiltration membrane.

Preferably, the preparation method of oxidant resistance in step (1) is as follows: polymerize monomer A, monomer B and monomer C in a reactor, the reaction temperature is 40-80°C, and the reaction time is 24-48 hours; After the reaction is finished, the oxidation resistance can be obtained by distillation under reduced pressure.

Preferably, the molar ratio of monomer A, monomer B and monomer C is 1:(0.1-0.4):(0.01-0.05).

Polyethyleneimine (PEI) is a kind of high-molecular organic matter, which usually has two forms: linear and dendritic. , can form a highly cross-linked space network structure with other polymers, the structure has a large molecular weight, stable performance, and is not easy to be lost, and can stably exist in PVDF. However, at present, there is no literature report on the application of PEI, a dendritic polymer crosslinking agent, in the preparation of PVDF ultrafiltration membranes. The oxidation resistance of a space highly cross-linked network structure is prepared by reacting the class or ester compound, and an oxidation resistance ultrafiltration membrane is prepared by using the oxidation resistance as an additive of the ultrafiltration membrane. The modified PVDF ultrafiltration membrane synthesized in the invention has the advantages of simple preparation process, less types of raw materials required, high product qualified rate, etc., and meanwhile, its oxidation resistance is obvious.

3. Beneficial effect

(1) The oxidation resistance synthesized by the present invention is a space highly cross-linked network structure, which can be stably present in PVDF, is not easy to be lost, and has good oxidation resistance;

(2) The oxidant-resistant medium-long-chain alkane amines synthesized by the present invention can neutralize and absorb the HCl released during the decomposition process of PVDF, and perform addition reaction with the formed double bond, thereby improving the oxidation resistance of PVDF material;

(3) The C=C double bonds and phenolic functional groups produced in the synthesis process of the present invention can also absorb and shield part of the harmful energy in the ultraviolet region, capture active free radicals excited by ultraviolet light, and quench excited state molecules , to decompose peroxides produced by ultraviolet light, therefore, the oxidation-resistant aeration hose of the present invention has the advantages of strong oxidation resistance and long service life;

(4) The oxidation-resistant ultrafiltration membrane prepared by the present invention has simple synthesis process, cheap and easy-to-obtain raw materials, high yield, excellent performance and environmental protection.

detailed description

The present invention will be further described below in conjunction with specific embodiments.

Example 1

A preparation method of an oxidation-resistant ultrafiltration membrane is as follows:

Step (1): Take PEI with a molecular weight of 50,000-100,000 in the molar ratio of 1:0.1:0.01 (weighed to prepare an aqueous solution, hereinafter referred to as PEI solution), dodecyltrimethylammonium bromide and butyl Hydroxyanishol, put dodecyltrimethylammonium bromide and butylhydroxyanishol in a reaction kettle, slowly add PEI solution dropwise to it, heat to 80°C and mix for 24 hours, after the reaction is completed, it can be obtained by vacuum distillation Oxidant resistance;

Step (2): Take PVDF powder: 100 parts; solvent dimethylacetamide: 40 parts; anti-oxidant: 0.5 parts, stir evenly, after defoaming and aging, use the traditional phase transformation method to let the casting liquid stand still and coagulate Glue and scraping membrane can be used to synthesize oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 10000 mg/L to run for 90 days, and the membrane flux decreased by 1%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Example 2

Other conditions of this instance are the same as embodiment 1, and the difference is:

In the step (1), the molar ratio is 1:0.2:0.03 to take PEI with a molecular weight of 100,000-500,000 range (formed into an aqueous solution after weighing, hereinafter referred to as PEI solution), dodecyltrimethylammonium bromide and tetraerythritol Esters, put dodecyltrimethylammonium bromide and tetraerythritol ester in a reaction kettle, slowly drop PEI solution into it, heat to 40°C and mix and react for 48h, and obtain oxidation resistance by vacuum distillation after the reaction;

Step (2) Take PVDF powder: 100 parts; solvent dimethylformamide: 60 parts; anti-oxidant: 1 part, stir evenly, after defoaming and aging, use the traditional phase transformation method to let the casting solution stand still and gel , Scrape the membrane to synthesize an oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 15000 mg/L to run for 70 days, and the membrane flux decreased by 0.8%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Example 3

Other conditions of this instance are the same as embodiment 1, and the difference is:

In the step (1), the molar ratio is 1:0.4:0.05 to take PEI (weighed to be prepared as an aqueous solution, hereinafter referred to as PEI solution), dodecyldimethylethylammonium bromide and For tert-butyl hydroquinone, put dodecyldimethylethylammonium bromide and tert-butyl hydroquinone in a reaction kettle, slowly add PEI solution dropwise, heat to 50°C for mixed reaction 36h, the oxidation resistance can be obtained by vacuum distillation after the reaction;

Step (2) Take PVDF powder: 100 parts; solvent (dimethyl sulfoxide: N-methylpyrrolidone = 1:1): 60 parts; anti-oxidant: 0.6 parts, stir evenly, after defoaming and curing, use traditional The phase transformation method puts the cast membrane solution to rest, gels, and scrapes the membrane to synthesize an oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 12000mg/L to run for 80 days, and the membrane flux decreased by 0.9%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Example 4

Other conditions of this instance are the same as embodiment 1, and the difference is:

In step (1), the molar ratio is 1:0.2:0.02 to take PEI with a molecular weight of 400,000-500,000 (weighed to prepare an aqueous solution, hereinafter referred to as PEI solution), tetradecyldimethylethyl tertiary amine and tertiary Butyl hydroquinone, place tetradecyl dimethyl ethyl ammonium bromide and tert-butyl hydroquinone in a reaction kettle, slowly add PEI solution dropwise, heat to 45°C and mix for 42 hours , after the reaction, the oxidation resistance can be obtained by distillation under reduced pressure;

Step (2) Take PVDF powder: 100 parts; solvent dimethyl sulfoxide: 50 parts; anti-oxidant: 0.7 parts, stir evenly, after defoaming and aging, use the traditional phase transformation method to let the casting solution stand still and gel , Scrape the membrane to synthesize an oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 11000 mg/L to run for 100 days, and the membrane flux decreased by 0.6%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Example 5

Other conditions of this instance are the same as embodiment 1, and the difference is:

In the step (1), the molar ratio is 1:0.1:0.02 to take PEI (weighed to be prepared as an aqueous solution, hereinafter referred to as PEI solution), tetradecyldimethylethylammonium chloride and Tetraerythritol ester, tetradecyl dimethyl ethyl ammonium chloride and tetraerythritol ester are placed in a reaction kettle, slowly drop PEI solution into it, heat to 52°C and mix for 28 hours. Oxidant resistance can be obtained;

Take PVDF powder in step (2): 100 parts; solvent N-methylpyrrolidone: 60 parts; anti-oxidant: 0.5 parts, stir evenly, after defoaming and aging, use the traditional phase transformation method to let the casting liquid stand still and solidify Glue and scraping membrane can be used to synthesize oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 16000 mg/L to run for 90 days, and the membrane flux decreased by 1%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Example 6

Other conditions of this instance are the same as embodiment 1, and the difference is:

In the step (1), the molar ratio is 1:0.3:0.04 to get PEI (weighed to be prepared as an aqueous solution, hereinafter referred to as PEI solution), Tetradecyldimethylethylammonium bromide and Tridecyl trimethyl ammonium bromide mixture, tetraerythritol ester, tetradecyl dimethyl ethyl ammonium bromide and tridecyl trimethyl ammonium bromide mixture, tetraerythritol ester are placed in the reaction kettle , slowly drop the PEI solution therein, heat to 45°C and mix for 42h, wherein the molar ratio of tetradecyldimethylethylammonium bromide and tridecyltrimethylammonium bromide is 1:1, and the reaction After the end, the oxidation resistance can be obtained by distillation under reduced pressure;

Take PVDF powder in step (2): 100 parts; solvent N-methylpyrrolidone: 50 parts; oxidation resistance: 0.6 parts, stir evenly, after defoaming and aging, use the traditional phase transformation method to let the casting liquid stand still and solidify Glue and scraping membrane can be used to synthesize oxidation-resistant polyvinylidene fluoride ultrafiltration membrane.

The oxidation-resistant ultrafiltration membrane prepared in this example was used in the oxidation test, and the oxidation-resistant ultrafiltration membrane was placed in the recycled water with residual chlorine of 14000 mg/L to run for 70 days, and the membrane flux decreased by 0.6%, indicating that the oxidation-resistant ultrafiltration membrane The anti-oxidation performance of the filter membrane is good.

Claims (10)

1. a resistance to oxidation milipore filter, is characterized in that: the parts by weight of the key component and each key component of preparing the raw material of described resistance to oxidation milipore filter are: PVDF powder: 100 parts; Solvent: 40-60 part; Antioxidant: 0.5-1 part.

2. a kind of resistance to oxidation milipore filter according to claim 1, is characterized in that: described solvent is one or more the mixing in dimethylacetylamide, dimethyl formamide, dimethyl sulfoxide (DMSO) or 1-METHYLPYRROLIDONE; Described antioxidant is formed by monomer A, monomers B and monomer C copolymerzation with cross-linking; Described monomer A is dendroid polymine; Described monomers B is chain alkyl amine substance; Described monomer C is phenols or ester type compound.

3. a kind of resistance to oxidation milipore filter according to claim 2, is characterized in that: the structural formula of described dendroid polymine is:

Wherein, n is 100-1000, and the molecular weight of described dendroid polymine is 50000-500000.

4. a kind of resistance to oxidation milipore filter according to claim 2, is characterized in that: the structural formula of described chain alkyl amine substance is:

In formula, m is 10-12, R is methyl or ethyl, and X is halogens.

5. a kind of resistance to oxidation milipore filter according to claim 4, is characterized in that: described chain alkyl amine substance is one or more in DTAC, DTAB, dodecyl dimethyl ethyl phosphonium bromide ammonium, dodecyldimethylamine base ethyl phosphonium bromide ammonium, dodecyldimethylamine base ethyl ammonium chloride, tridecyl trimethylammonium bromide etc.

6. a kind of resistance to oxidation milipore filter according to claim 2, is characterized in that: described monomer C is that butylhydroxy fennel phenol, tetrapentaerythritol ester or the tert-butyl group are to the one in two benzenediols.

7. a kind of resistance to oxidation milipore filter according to right 1 to 6, is characterized in that: it is run 70-100 days in the recycle-water of 10000-16000mg/L that described resistance to oxidation milipore filter is placed on chlorine residue, and membrane flux reduces 0.6%-1%.

8. a preparation method for resistance to oxidation milipore filter, main preparation process is:

(1) in proportion antioxidant is prepared in monomer A, monomers B and monomer C reaction;

(2) getting 100 parts of Kynoar powders is dissolved in 40-60 part solvent, get antioxidant 0.5-1 part that step (1) is obtained, stir, after deaeration slaking, adopt traditional phase transition method by casting solution leave standstill, gel, knifing, can polyvinylidene fluoride (PVDF) ultrafiltration membrane be synthesized.

9. the preparation method of a kind of resistance to oxidation milipore filter according to claim 8, it is characterized in that: in step (1), the preparation method of antioxidant is: by monomer A, monomers B and monomer C polymerization reaction take place in a kettle., reaction temperature is 40 ~ 80 DEG C, and the reaction time is 24 ~ 48h; Reaction terminates rear decompression distillation and can obtain described antioxidant.

10. the preparation method of a kind of resistance to oxidation milipore filter according to claim 9, is characterized in that: the mol ratio of monomer A, monomers B and monomer C is 1:(0.1-0.4): (0.01-0.05).