A super-hydrophobic nanofiber membrane for sewage treatment and preparation method thereof

Abstract

The invention relates to the technical field of functional materials, and provides a super-hydrophobic nanofiber membrane for sewage treatment. The preparation method thereof comprises the following steps: dissolving Bi salt and W salt, S source, doped Zn source and polyethylene glycol in a propylene glycol / water solvent, and stirring to form a uniform mixed solution; charging the mixed solution into a reactor, and reacting at 180-200 DEG C for 10-20 hours; after the reaction is completed, washing and drying to obtain Zn-doped Bi2S3-WS2; dissolving polyvinylidene fluoride and hexadecyltrimethoxysilane in an organic solvent in a certain proportion; heating and stirring to dissolve at a temperature of 40-50 DEG C, then adding Zn-doped Bi2S3-WS2, mixing evenly and performing electrostatic spinning to prepare a super-hydrophobic nanofiber membrane for sewage treatment, wherein the surface contact angle of the super-hydrophobic membrane material can reach 159 degrees, oil-water separation can be efficiently achieved, and the photocatalytic degradation efficiency of pollutants in water is good.

Description

Technical Field

[0001] The present application relates to a nanofiber membrane, specifically a super hydrophobic nanofiber membrane for sewage treatment and a preparation method thereof. Background Art

[0002] Oily sewage refers to sewage containing lipids (such as fatty acids, soap feces, fats, waxes, etc.) and various oils (such as mineral oils, animal and plant oils). Oily sewage has high COD and BOD, has a certain smell and color, is flammable, and is easily oxidized and decomposed. It is generally lighter than water and difficult to dissolve in water. Oily sewage is widespread, large in volume, and has serious harm, which has adverse effects on humans, animals, plants, and even the entire ecosystem. The impact of oil substances on the environment is multifaceted, such as the harm to water bodies: the formation of oil film on the water surface can hinder the reoxygenation of the water body. Due to the reduction of dissolved oxygen in the water body, the photosynthesis of algae is restricted, affecting the normal growth of aquatic organisms, making aquatic plants have oily or toxic smells, and even making the water body smelly, destroying the utilization value of water resources; oil adheres to the gills of fish, which can suffocate the fish. When the concentration increases further, the fish cannot survive; it adheres to algae and plankton, which can kill them; oil inhibits the laying and hatching of water birds, and in severe cases, it causes the death of a large number of birds. When oily wastewater is used to irrigate farmland, oil and its derivatives will cover the surface of soil and plants, block the gaps in the soil, prevent air from penetrating, and prevent the soil and microorganisms from normal metabolism, which will reduce the quality and practical value of agricultural products. In serious cases, it will cause crop yield reduction or death. Oil will migrate downward in the soil and may cause serious groundwater pollution. Therefore, it is of great practical significance to separate oil from water in oily wastewater and degrade pollutants. Summary of the invention

[0003] The purpose of the present invention is to provide a super hydrophobic nanofiber membrane for sewage treatment, which has a simple preparation process and low cost, can efficiently separate oil and water, and can quickly degrade pollutants in sewage.

[0004] A method for preparing a super-hydrophobic nanofiber membrane for sewage treatment comprises the following steps:

[0005] (1) Preparation of photocatalytic degradation materials:

[0006] Dissolve Bi salt and W salt, S source, doped Zn source and polyethylene glycol in a propylene glycol / water solvent and stir to form a uniform mixed solution; put the mixed solution into a reactor and react at 180-200°C for 10-20h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2;

[0007] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0008] Dissolve polyvinylidene fluoride and hexadecyltrimethoxysilane in an organic solvent in a certain proportion; heat and stir to dissolve at a temperature of 40-50°C, then add Zn-doped Bi2S3-WS2, mix evenly and then perform electrostatic spinning to prepare a super hydrophobic nanofiber membrane for sewage treatment.

[0009] Further, the molar ratio of Bi salt to W salt, S source and doped Zn source is (1-2): (1-2): (3.5-7): (0.01-0.05);

[0010] Further, the mass ratio of Bi salt to polyethylene glycol is 1:(0.2-0.5);

[0011] Further, the volume ratio of propylene glycol / water is (5-7):1;

[0012] Furthermore, the organic solvent in step (2) is N,N-dimethylformamide;

[0013] Furthermore, the voltage of electrospinning was 10–20 kV, the spinning distance was 15–20 cm, and the flow rate was 0.1–1 mL / h;

[0014] Further, the mass ratio of polyvinylidene fluoride to hexadecyltrimethoxysilane is 1:(0.1-0.5);

[0015] Compared with the prior art, the technical effects achieved by this application are:

[0016] (1) Polyvinylidene fluoride and hexadecyltrimethoxysilane were electrospun to prepare a nanofiber membrane with superhydrophobic properties. The Zn-doped Bi2S3-WS2 with an uneven flower-like surface was directly added to the electrospinning solution to participate in the spinning. On the one hand, it is not easy to fall off. On the other hand, it can greatly increase the roughness of the nanofiber surface, thereby improving the hydrophobic properties of the fiber membrane and achieving efficient oil-water separation.

[0017] (2) High specific surface area and multiple reaction sites with uneven flower-like surface of Zn-doped Bi2S3-WS2, Bi2S 3、 WS2 forms a heterojunction structure, which significantly improves the separation efficiency of photogenerated electrons and holes. By synchronously doping it with Zn, the light absorption response range is broadened, the migration rate of photogenerated carriers is accelerated, and the photocatalytic performance of Bi2S3-WS2 is improved.

[0018] (3) The one-pot preparation process is simple, with mild reaction conditions, and is more suitable for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1This is a scanning electron microscope image of the superhydrophobic nanofiber membrane for sewage treatment prepared in this application.

[0020] Figure 2 The catalytic degradation performance diagram of the nanofiber membrane of Example 1 and Comparative Examples 1-3 of the present application on organic pollutants at different times. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0022] Example 1

[0023] (1) Preparation of photocatalytic degradation materials:

[0024] Weigh 0.97g of Bi(NO3)3·5H2O, 0.33g of Na2WO4·2H2O, 0.38g of thiourea CH4N2S, 5mg of Zn(NO3)2·6H2O, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water is 5:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 180°C for 10h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2;

[0025] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0026] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Zn-doped Bi2S3-WS2, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0027] Example 2

[0028] (1) Preparation of photocatalytic degradation materials:

[0029] Weigh 0.97g of Bi(NO3)3·5H2O, 0.33g of Na2WO4·2H2O, 0.38g of thiourea CH4N2S, 5mg of Zn(NO3)2·6H2O, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water is 5:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 180°C for 10h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2;

[0030] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0031] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Zn-doped Bi2S3-WS2, mix well and then perform electrospinning. The electrospinning voltage is 18 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0032] Example 3

[0033] (1) Preparation of photocatalytic degradation materials:

[0034] Weigh 0.97g of Bi(NO3)3·5H2O, 0.33g of Na2WO4·2H2O, 0.38g of CH4N2S, 5mg of Zn(NO3)2·6H2O, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water is 5:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 200°C for 10h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2;

[0035] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0036] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.3g of Zn-doped Bi2S3-WS2, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0037] Example 4

[0038] (1) Preparation of photocatalytic degradation materials:

[0039] Weigh 0.97g of Bi(NO3)3·5H2O, 0.33g of Na2WO4·2H2O, 0.38g of thiourea CH4N2S, 5mg of Zn(NO3)2·6H2O, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water is 6:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 200°C for 10h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2;

[0040] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0041] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Zn-doped Bi2S3-WS2, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0042] Comparative Example 1

[0043] (1) Preparation of photocatalytic degradation materials:

[0044] 0.97 g of Bi(NO3)3·5H2O, 0.228 g of CH4N2S, 5 mg of Zn(NO3)2·6H2O and 0.29 g of polyethylene glycol were weighed and dissolved in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water was 5:1; the mixture was stirred for 20 min to form a uniform mixed solution; the mixed solution was charged into a reactor and reacted at 180°C for 10 h; after the reaction, the mixture was washed and dried to obtain Zn-doped Bi2S3;

[0045] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0046] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Zn-doped Bi2S3, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0047] Comparative Example 2

[0048] (1) Preparation of photocatalytic degradation materials:

[0049] Weigh 0.33g of Na2WO4·2H2O, 0.15g of CH4N2S, 5mg of Zn(NO3)2·6H2O, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, with a volume ratio of propylene glycol / water of 5:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 180°C for 10h; after the reaction, wash and dry to obtain Zn-doped WS2;

[0050] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0051] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Zn-doped WS2, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0052] Comparative Example 3

[0053] (1) Preparation of photocatalytic degradation materials:

[0054] Weigh 0.97g of Bi(NO3)3·5H2O, 0.33g of Na2WO4·2H2O, 0.38g of CH4N2S, and 0.29g of polyethylene glycol and dissolve them in a propylene glycol / water solvent, wherein the volume ratio of propylene glycol / water is 5:1; stir for 20min to form a uniform mixed solution; charge the mixed solution into a reactor and react at 180°C for 10h; after the reaction, wash and dry to obtain Bi2S3-WS2;

[0055] (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment:

[0056] Weigh 2g of polyvinylidene fluoride and 0.5g of hexadecyltrimethoxysilane and dissolve them in 15ml of organic solvent N,N-dimethylformamide; heat and stir to dissolve at 50°C, then add 0.2g of Bi2S3-WS2, mix well and then perform electrospinning. The electrospinning voltage is 15 kV, the spinning distance is 15 cm, and the flow rate is 0.5 mL / h to prepare a superhydrophobic nanofiber membrane for sewage treatment.

[0057] Test 1: Using gasoline: water with a volume ratio of 10:1 as the test object, the oil-water separation efficiency of Examples 1-4 and Comparative Examples 1-3 was tested. The experimental results are shown in Table 1 below.

[0058] Test 2: The contact angle test was performed on the nanofiber membranes of Examples 1-4 and Comparative Examples 1-3. The experimental results are shown in Table 1 below.

[0059] Test 3: The nanofiber membrane materials of Example 1 and Comparative Examples 1-3 were immersed in a methylene blue solution, kept away from light for 1 hour, and then irradiated with a 300W xenon lamp to test the degradation rate of methylene blue. The experimental results are as follows: Figure 2 .

[0060] Table 1 The test results of oil-water separation efficiency and contact angle of Examples 1-4 and Comparative Examples 1-3.

[0061]

Claims

1. A method for preparing a super-hydrophobic nanofiber membrane for sewage treatment, comprising the following steps: (1) Preparation of photocatalytic degradation materials: Dissolve Bi salt and W salt, S source, doped Zn source and polyethylene glycol in a propylene glycol / water solvent and stir to form a uniform mixed solution; put the mixed solution into a reactor and react at 180-200°C for 10-20h; after the reaction, wash and dry to obtain Zn-doped Bi2S3-WS2; (2) Preparation of super-hydrophobic nanofiber membrane for sewage treatment: Dissolve polyvinylidene fluoride and hexadecyltrimethoxysilane in an organic solvent in a certain mass ratio; heat and stir to dissolve at a temperature of 40-50°C, then add Zn-doped Bi2S3-WS2, mix evenly and perform electrostatic spinning to prepare a super hydrophobic nanofiber membrane for sewage treatment.

2. The method for preparing a super-hydrophobic nanofiber membrane for sewage treatment according to claim 1, characterized in that: The molar ratio of Bi salt, W salt, S source and doped Zn source is (1-2): (1-2): (3.5-7): (0.01-0.05).

3. The method for preparing a super-hydrophobic nanofiber membrane for sewage treatment according to claim 1, characterized in that: The mass ratio of Bi salt to polyethylene glycol is 1:(0.2-0.5).

4. The method for preparing a super-hydrophobic nanofiber membrane for sewage treatment according to claim 1, characterized in that: The volume ratio of propylene glycol / water is (5-7):

1.

5. The method for preparing a super-hydrophobic nanofiber membrane for sewage treatment according to claim 1, characterized in that: The organic solvent in step (2) is N,N-dimethylformamide.

6. The method for preparing a super-hydrophobic nanofiber membrane for sewage treatment according to claim 1, characterized in that: The voltage of electrospinning was 10-20 kV, the spinning distance was 15-20 cm, and the flow rate was 0.1~1 mL / h.

7. A super hydrophobic nanofiber membrane for sewage treatment, characterized in that: The preparation method according to claim 1 is used for preparation.

Images