Electrostatic spinning fiber base membrane for water treatment and preparation method thereof

Abstract

The invention discloses an electrostatic spinning fiber base membrane for water treatment, which comprises a composite polymer fiber matrix and keratin, and the keratin is attached to the fiber surface; the composite polymer fiber matrix comprises polybutylene terephthalate, hydrophilic modified polyester and polyvinyl alcohol; the hydrophilic modified polyester is prepared from polyester polyol containing a morpholinedione structure and terephthalic acid through esterification. By compounding hydrophilic modified polyester, polyvinyl alcohol and keratin, the porous structure of the fiber base membrane is optimized, the hydrophilic performance of the base membrane is improved, the decontamination effect is improved, meanwhile, the mechanical performance of the fiber base membrane is optimized, and the service life of the fiber base membrane is prolonged; cysteine is released through keratin hydrolysis, an electron donor is provided, the method is suitable for strain growth, and the sewage treatment effect is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to an electrostatic spinning fiber-based membrane for water treatment and a preparation method thereof. Background Art

[0002] Electrospinning is a simple and convenient technology for preparing ultrafine nanofibers under high voltage electrostatic action. The nanofiber membrane prepared by this method has the characteristics of high porosity, high specific surface area, and small pore size, and is widely used in the field of water treatment. The common polyethylene terephthalate fiber itself is hydrophobic, which limits its effective contact with pollutants in the water phase, reduces adsorption efficiency, and is not conducive to the adhesion and growth of certain microorganisms.

[0003] Therefore, it is necessary to improve the electrospun fiber-based membrane in the prior art. Summary of the invention

[0004] One of the purposes of the present invention is to overcome the defects existing in the prior art and provide an electrospun fiber-based membrane for water treatment. By compounding hydrophilically modified polyester, polyvinyl alcohol and keratin, the porous structure of the fiber-based membrane is optimized and the hydrophilicity of the base membrane is improved, thereby improving the dirt removal effect, while optimizing its mechanical properties and increasing its service life. Keratin is hydrolyzed to release cysteine, providing an electron donor, which is suitable for bacterial growth and further improving the sewage treatment effect.

[0005] In order to achieve the above-mentioned process effect, the technical solution of the present invention is: an electrospun fiber-based membrane for water treatment, comprising a composite polymer fiber matrix and keratin, wherein the keratin is attached to the fiber surface;

[0006] The composite polymer fiber matrix includes polybutylene terephthalate, hydrophilic modified polyester and polyvinyl alcohol;

[0007] The hydrophilic modified polyester is prepared by esterifying polyester polyol containing morpholinedione structure with terephthalate.

[0008] The preferred technical solution is that the mass ratio of the polybutylene terephthalate, the hydrophilic modified polyester and the polyvinyl alcohol is (25-35):(8-10):(1-2).

[0009] The preferred technical solution is that the mass ratio of the composite polymer fiber matrix to keratin is 10:(0.1-0.2).

[0010] The preferred technical solution is that the polyester polyol containing morpholinedione structure is prepared by mixing sebacic acid, neopentyl glycol, hexylene glycol and sodium terephthalic acid sulfonate, reacting at a temperature of 200 to 250° C. for 5 to 6 hours under nitrogen protection; then adding a morpholinedione derivative and reacting at a temperature of 230 to 250° C. for 2 to 3 hours.

[0011] The preferred technical solution is that the mass ratio of the polyester polyol containing morpholinedione structure to terephthalic acid is (30-40): (10-20).

[0012] A preferred technical solution is that the number average molecular weight of the polybutylene terephthalate is between 20,000 and 50,000, and the number average molecular weight of the polyvinyl alcohol is between 80,000 and 130,000.

[0013] The second object of the present invention is to overcome the defects existing in the prior art and provide a method for preparing an electrospun fiber-based membrane for water treatment, comprising the following steps:

[0014] S1: The composite polymer raw material and keratin are dissolved in an organic solvent to obtain a mixed spinning solution;

[0015] S2: The mixed spinning solution is electrospinned to prepare a base film composed of a composite polymer fiber matrix and keratin.

[0016] The preferred technical solution is that the spinning parameters in S2 are: temperature of 25-30°C, humidity of 30%-40%, pressure of 22-30 kV, injection speed of 0.01-0.05 ml / min, and receiving distance of 20-30 cm.

[0017] A preferred technical solution is that the organic solvent is hexafluoroisopropanol.

[0018] A preferred technical solution is that the mass concentration of the composite polymer raw material is 100-150 g / L.

[0019] The advantages and beneficial effects of the present invention are:

[0020] The electrospun fiber-based membrane for water treatment is compounded by hydrophilic modified polyester, polyvinyl alcohol and keratin to optimize the porous structure of the fiber-based membrane and improve the hydrophilicity of the base membrane, thereby improving the decontamination effect, while optimizing its mechanical properties and increasing its service life.

[0021] The release of cysteine ​​through keratin hydrolysis provides an electron donor, which is suitable for bacterial growth and further improves the sewage treatment effect. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0023] Hydrophilic modified polyester

[0024] It is prepared by esterifying terephthalate with polyester polyol containing morpholinedione structure.

[0025] The polyester polyol containing morpholine dione structure is prepared by mixing 90-100 parts of sebacic acid, 70-75 parts of neopentyl glycol, 20-25 parts of hexanediol, and 4-5 parts of sodium sulfonate terephthalate, reacting at 200-250°C for 5-6 hours under nitrogen protection; then adding 0.8-1 parts of morpholine dione derivative, and reacting at 230-250°C for 2-3 hours. The morpholine dione structure can improve the hydrophilicity of the fiber-based membrane, has rigidity, and can improve the thermal stability of the fiber-based membrane. Sodium sulfonate terephthalate is also added to introduce ionic groups, further improving the hydrophilicity of the fiber-based membrane.

[0026] Preparation of morpholine dione derivatives: 59g of aminomalonic acid and 52g of neopentyl glycol are mixed, 142ml of 30wt% hydrochloric acid is added, the temperature is raised to 90°C, stirred and reacted for 25min, triethylamine is added after cooling to room temperature, the mixture is allowed to stand, filtered, washed, and recrystallized from triethylamine to obtain an esterification pre-product; then 51g of the esterification pre-product and 0.5L of dioxane are mixed and dissolved in a sodium hydroxide solution, and the mixture is kept warm at 4°C under nitrogen protection, 60g of bromopropionyl bromide is added dropwise for 1h, and the reaction is kept warm for 1h. After the reaction is completed, the pH value of the reaction solution is adjusted to 3 by acid-base, and the mixture is extracted with ethyl acetate, filtered, and recrystallized to obtain a bromopropionyl compound; then 50g of triethylamine and 5L of N,N-dimethylformamide are mixed, the temperature is raised to 80°C, 150g of the bromopropionyl compound is slowly added dropwise, the bromopropionyl compound is reacted for 5h, extracted with ethyl acetate, filtered, and recrystallized to obtain a morpholine dione derivative.

[0027] Among them, neopentyl glycol contains neopentyl in its molecular structure, which makes the polyester made from it have excellent thermal stability; polyester made from neopentyl glycol has good resistance to acids, alkalis and other chemicals, and shows excellent hydrolysis resistance; it usually shows a good balance between flexibility and hardness, and has high impact strength; it can still maintain good flexibility and elasticity at low temperatures. Hexanediol is a longer-chain diol, so it can increase the distance between polyester chains, thereby improving the softness and ductility of the material; and it is more wear-resistant than polyester made from short-chain diols.

[0028] Keratin

[0029] The raw material is wool. First, the wool is immersed in 80°C petroleum ether to remove lanolin. Then, 10g of wool, 200ml of a mixture of sodium metabisulfite (0.5mol / L), urea (8mol / L), and sodium dodecyl sulfate (0.1mol / L) are evenly mixed and reacted in a water bath at 60°C for 4 hours to obtain a crude keratin solution. The crude keratin solution is then filtered and dialyzed, and freeze-dried to obtain wool keratin powder.

[0030] Example 1

[0031] The electrospun fiber-based membrane for water treatment comprises a composite polymer fiber matrix and keratin, wherein the keratin is attached to the fiber surface, and the mass ratio of the composite polymer fiber matrix to the keratin is 10:0.15.

[0032] The composite polymer fiber matrix includes polybutylene terephthalate, hydrophilic modified polyester and polyvinyl alcohol in a mass ratio of 30:8.5:1.5;

[0033] The hydrophilic modified polyester is prepared by esterifying a polyester polyol containing a morpholine dione structure with terephthalate in a mass ratio of 36:14. The polyester polyol containing a morpholine dione structure is mixed with 96 parts of sebacic acid, 72 parts of neopentyl glycol, 25 parts of hexanediol, and 4.3 parts of sodium terephthalate sulfonate, and reacted at a temperature of 230°C for 5 hours under nitrogen protection; then 0.9 parts of a morpholine dione derivative is added and reacted at a temperature of 240°C for 3 hours.

[0034] The preparation method of the electrospun fiber-based membrane for water treatment comprises the following steps:

[0035] S1: a composite polymer raw material and keratin are dissolved in hexafluoroisopropanol to obtain a mixed spinning solution, wherein the mass concentration of the composite polymer raw material is 120 g / L, i.e., 120 g of the composite polymer raw material is taken from 1 L of hexafluoroisopropanol;

[0036] S2: The mixed spinning solution is electrospinned to prepare a base film composed of a composite polymer fiber matrix and keratin.

[0037] The spinning parameters in S2 were: temperature of 28° C., humidity of 32%, pressure of 25 kV, injection speed of 0.03 ml / min, and receiving distance of 23 cm.

[0038] Example 2

[0039] Example 2 is based on Example 1, except that the composite polymer fiber matrix includes polybutylene terephthalate, hydrophilic modified polyester and polyvinyl alcohol in a mass ratio of 25:10:2. Other components, process steps and parameters remain unchanged.

[0040] Example 3

[0041] Example 3 is based on Example 1, except that the mass ratio of the composite polymer fiber matrix to keratin is 10:5. Other components, process steps and parameters remain unchanged.

[0042] Comparative Example 1

[0043] Comparative Example 1 is based on Example 1, except that the electrospun fiber-based membrane for water treatment only includes a composite polymer fiber matrix without adding keratin. Other components, process steps and parameters remain unchanged.

[0044] Comparative Example 2

[0045] Comparative Example 2 is based on Example 1, except that the composite polymer fiber matrix includes polybutylene terephthalate and polyvinyl alcohol in a mass ratio of 30:10, and does not include hydrophilic modified polyester. Other compositions, process steps and parameters remain unchanged.

[0046] Comparative Example 3

[0047] Comparative Example 3 is based on Example 1, except that the composite polymer fiber matrix includes polybutylene terephthalate and hydrophilic modified polyester in a mass ratio of 30:10, and does not include polyvinyl alcohol. Other compositions, process steps and parameters remain unchanged.

[0048] Performance Testing:

[0049] 1. Tensile strength: tested by electronic universal testing machine CMT6503, the fiber-based membrane is cut into 70mm*10mm, and the tensile speed is 20mm / min;

[0050] 2. Elongation at break: Tested by electronic universal testing machine CMT6503, the fiber-based film was cut into 70mm*10mm, and the stretching speed was 20mm / min;

[0051] 3. Hydrophilicity test: Tested by water contact angle tester, the water drop size for each test is 10μL. The smaller the water contact angle, the better the hydrophilicity;

[0052] 4. Decontamination effect: Cut the fiber substrate into 10cm*10cm square samples, weigh the gram weight M0 of the base film sample before treatment, prepare wastewater: prepare a 100L bucket at room temperature, pour 50L of tap water and 5L of sludge (ordinary sludge and stinking ditch sludge), where the mass ratio of biochemical oxygen demand, nitrogen and phosphorus is 100:4:1.5, and obtain organic wastewater; prepare bacterial solution: take a 5L beaker and fill half a cup of tap water, weigh an appropriate amount of composite bacteria (nitrifying bacteria: denitrifying bacteria: Bacillus: Pseudomonas = 5:5:4:6), dissolve the composite bacteria in the beaker, where the mass ratio of tap water to composite bacteria is 1000:

[0053] 1.5, and finally, after the oxygen pump is turned on to activate the bacteria by aeration for 2 hours, it is directly poured into the organic wastewater, and then aerated and cultivated for 16 days, and 100g of glucose is added at a fixed time every day to obtain the wastewater composite bacterial solution. The cut sample is placed in the wastewater composite bacterial solution, and after aeration for 15 days, the basement membrane sample of the treated sewage is placed in an oven at 110°C for drying, and the gram weight M1 of the treated basement membrane sample is weighed, and the difference in gram values ​​between M1 and M0 is compared. The larger the value, the more suitable the porous structure of the basement membrane obtained by combining keratin and composite polymer fibers is for hiding bacteria. After the bacteria act on the keratin, cysteine ​​is hydrolyzed and released, providing an electron donor, which is suitable for the growth of bacteria, proving that keratin can play a role as a filler on the surface of the basement membrane.

[0054] The performance tests of the embodiments and comparative examples are shown in the following table:

[0055]

[0056] Compared with Example 1, the average diameter of the fibers in Example 2 increases, and the density of the porous structure of the base membrane decreases, which has a negative impact on the decontamination effect.

[0057] Compared with Example 1, Example 3 has an increased keratin content, which has a negative effect on the mechanical properties of the basement membrane. The area of ​​the coated fibers is increased, resulting in less exposure of hydrophilic groups, which has a negative effect on hydrophilicity. Although the decontamination effect is increased, it has a negative effect on the stability of the mechanical properties of the basement membrane.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An electrospun fiber-based membrane for water treatment, characterized in that: It includes a composite polymer fiber matrix and keratin, wherein the keratin is attached to the fiber surface; The composite polymer fiber matrix includes polybutylene terephthalate, hydrophilic modified polyester and polyvinyl alcohol; The hydrophilic modified polyester is prepared by esterifying polyester polyol containing morpholinedione structure with terephthalate.

2. The electrospun fiber-based membrane for water treatment according to claim 1, characterized in that: The mass ratio of the polybutylene terephthalate, the hydrophilic modified polyester and the polyvinyl alcohol is (25-35): (8-10): (1-2).

3. The electrospun fiber-based membrane for water treatment according to claim 2, characterized in that: The mass ratio of the composite polymer fiber matrix to keratin is 10:(0.1-0.2).

4. The electrospun fiber-based membrane for water treatment according to claim 2, characterized in that: The polyester polyol containing morpholine dione structure is prepared by mixing sebacic acid, neopentyl glycol, hexylene glycol and sodium sulfonate of terephthalic acid, reacting at 200-250° C. for 5-6 hours under nitrogen protection; then adding morpholine dione derivative and reacting at 230-250° C. for 2-3 hours.

5. The electrospun fiber-based membrane for water treatment according to claim 4, characterized in that: The mass ratio of the polyester polyol containing morpholinedione structure to terephthalic acid is (30-40): (10-20).

6. The electrospun fiber-based membrane for water treatment according to claim 1 or 2, characterized in that: The number average molecular weight of the polybutylene terephthalate is between 20,000 and 50,000, and the number average molecular weight of the polyvinyl alcohol is between 80,000 and 130,000.

7. A method for preparing an electrospun fiber-based membrane for water treatment, characterized in that: The following steps are involved: S1: The composite polymer raw material and keratin are dissolved in an organic solvent to obtain a mixed spinning solution; S2: The mixed spinning solution is electrospinned to prepare a base film composed of a composite polymer fiber matrix and keratin.

8. The method for preparing an electrospun fiber-based membrane for water treatment according to claim 7, characterized in that: The spinning parameters in S2 are as follows: temperature of 25-30° C., humidity of 30%-40%, pressure of 22-30 kV, injection speed of 0.01-0.05 ml / min, and receiving distance of 20-30 cm.

9. The method for preparing an electrospun fiber-based membrane for water treatment according to claim 7, characterized in that: The organic solvent is hexafluoroisopropanol.

10. The method for preparing an electrospun fiber-based membrane for water treatment according to claim 9, characterized in that: The mass concentration of the composite polymer raw material is 100-150 g / L.

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