CN116553705A - A composite nanofibrous membrane for immobilized microorganisms to treat diesel polluted water and its preparation method - Google Patents

Abstract

The invention discloses a composite nanofiber membrane for repairing diesel polluted water by immobilized microorganisms and a preparation method thereof. The composite fiber membrane is specifically a thermoplastic polyurethane/nano hydroxyapatite composite nanofiber membrane, has excellent biocompatibility and mechanical strength, is nontoxic and harmless, and has considerable cost benefit. After diesel pollution water is put into the composite nanofiber membrane, diesel at a water/oil interface can be quickly adsorbed at first, so that the toxic effect of further diffusion of the diesel on water environment is prevented; then, as the nano particles on the membrane provide additional adsorption sites, a large amount of free bacteria are adsorbed on the membrane, so that the metabolic activity of bacterial cells and the resistance to the toxicity of stubborn compounds are improved, the affinity of hydrophobic compounds to cells is enhanced, and the degradation rate of diesel hydrocarbon by microbial cells is improved. The invention expands the application of the composite nanofiber membrane in the field of water pollution treatment while realizing the effect of improving the diesel sewage restoration.

Description

A composite nanofiber membrane for immobilized microorganisms to treat diesel polluted water and its preparation method

technical field

The invention belongs to the technical field of materials, and in particular relates to a composite nanofibrous membrane for immobilized microorganisms to repair diesel-polluted water and a preparation method thereof.

Background technique

Oil is one of the most important resources in modern industry, as long as oil is extracted, transported, stored and used, there will be a risk of spillage. Oily wastes are considered serious persistent hazardous pollutants because they can cause widespread damage to ecosystems, including contamination of sediments and water. These accidents have brought great harm to the economy, the environment, and even human health. Efficient mitigation measures are urgently needed to remediate petroleum hydrocarbon-contaminated water. However, the remediation of petroleum hydrocarbon-contaminated environments remains challenging due to the low solubility, nonpolarity, and hydrophobicity of petroleum hydrocarbons. Common treatments, such as the application of chemical dispersants, may be potentially toxic to water bodies, making their use controversial. Therefore, the existing treatment strategies have limited remediation effects on oil-contaminated water, and are likely to cause secondary damage to the water environment. In order to remediate oil-contaminated water more effectively, the immobilized bacterial remediation carrier material with environmental friendliness and sustainable remediation is expected to become an effective strategy for water environment treatment.

Immobilization of microorganisms increases bacterial survival, metabolic activity, and resistance to toxic effects of recalcitrant compounds compared to free cells. Immobilization of microorganisms on appropriate supports can be exploited in many processes and allows easy recovery and reuse of bacteria. At present, many studies focus on the carrier that microorganisms can attach to, such as polyurethane foam (PUF); polycaprolactone (PCL) sponge and so on. They have known adsorption capacity for bacterial cells and hydrophobic compounds, but the disadvantage is that their loading rate and processing efficiency need to be further improved due to structural limitations. Another example is inorganic materials such as magnetic nanoparticles; modified bamboo charcoal, etc. These products are effective, but one of the disadvantages is that they are not biodegradable or difficult to recycle. Therefore, there is an urgent need for a carrier material that is biocompatible, insoluble, non-toxic to fixed cells and the environment, easy to obtain, and easy to recycle. In addition, scaffolds need to consist of highly interconnected macroscopic and microporous networks to facilitate cell migration and nutrient distribution. To meet the above conditions, immobilization materials with both high adsorption capacity and improved affinity between microbial cells and hydrophobic substrates are a promising choice.

Among the different methods for producing porous structured biopolymers, electrospinning technology is one of the most studied because of its adaptability to large-scale production, simplicity and availability, all factors contributing to cost-effectiveness. Fibers with different diameters from nanometer to micrometer scale can be produced using electrospinning technology. Compared with other porous structures, electrospun nanofibrous membranes have higher specific surface area and larger porosity. Therefore, electrospun membranes are widely used in oil spill remediation, removal of toxic metal ions from wastewater, and biomedicine. The good biocompatibility of the TPU nanofiber membrane can effectively stabilize the microorganisms, and its excellent mechanical strength and corrosion resistance make it better adapt to the external adverse environment, and it is non-toxic and harmless and has considerable cost-effectiveness. Hydroxyapatite is a typical environment-friendly functional material, which has good biocompatibility, high adsorption capacity, and high stability. It has received extensive attention in the fields of soil remediation and wastewater treatment. Therefore, introducing it into the TPU fiber membrane can improve the bioactivity and biocompatibility of the composite material, and make the bacterial cells better adhere to the scaffold. However, there is a lack of research on the preparation of thermoplastic polyurethane (TPU)/nano-hydroxyapatite-modified nanofibrous membranes using electrospinning technology as a carrier for oil removal. The high adsorption characteristics alone are enough to illustrate its potential, which has great research prospects in the field of treating petroleum hydrocarbon-contaminated water.

Contents of the invention

Based on this, the present invention provides a composite nanofibrous membrane containing hydroxyapatite. First, this composite nanofiber membrane has excellent mechanical, corrosion resistance and biocompatibility, and can adapt to various external adverse environments and smooth Repair polluted water; secondly, it is non-toxic and harmless and will not cause secondary damage to the environment during the repair process; finally, the nano-hydroxyapatite introduced by it is environmentally friendly and highly adsorbable, which greatly increases the adsorption on the membrane site, which improves the effect of immobilized microorganisms and increases the affinity between cells and hydrophobic substrates, thereby achieving the purpose of improving the degradation efficiency of diesel in polluted water. Therefore, the present invention combines the three technologies of electrospinning, microorganism immobilization and bioremediation, and expands the application of fiber membranes in the field of water treatment while realizing efficient repair of diesel-polluted water.

To achieve the above object, the present invention adopts the following technical solutions:

A kind of composite nanofibrous film that is used for immobilized microorganism repairing diesel oil polluted water, its preparation method comprises the following steps:

(1) Add needle-shaped nano-hydroxyapatite to the solvent system composed of N,N-dimethylformamide and acetone, perform the first ultrasonic wave, then add polyester thermoplastic polyurethane, stir evenly, and carry out the second Secondary ultrasonication, static defoaming, to obtain a uniform spinning solution S3;

(2) Spinning the spinning solution S3 by electrospinning to obtain a thermoplastic polyurethane/nano-hydroxyapatite composite nanofiber membrane (TPU/nHA composite nanofiber membrane);

(3) After drying the TPU/nHA composite nanofiber membrane, a composite nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was obtained.

Further, in step (1), the solvent system is composed of N,N-dimethylformamide and acetone in a volume ratio of 3:1, and the ratio of the needle-shaped nano-hydroxyapatite:solvent system is 0.5- 1.5: 100w/v, the time of the first ultrasonic treatment is 10-30min, the stirring speed is 120r/min, the temperature is 30°C, the time is 5-10h, the time of the second ultrasonic treatment is 10-30min, The standing time is 5 to 15 minutes;

Further, in step (2), the spinning voltage is controlled to be 10-20kv, and the spinning distance is 10-20cm; further, in step (3), the post-drying treatment step is to use a vacuum oven (-0.085 MPa) at 65°C for 5-10 days to evaporate all the solvents.

The composite nanofibrous membrane prepared by the above method for immobilized microorganisms to treat diesel polluted water has broad application prospects in the field of water treatment:

(1) Composite nanofibrous membranes as adsorbable hydrophobic substrates. When thrown into polluted water, it can quickly absorb diesel oil floating on the water/oil interface.

(2) Composite nanofibrous membrane as a carrier for bacterial cell immobilization. The introduced nanoparticles increase the adsorption sites on the membrane and improve the effect of immobilizing microorganisms.

(3) As a composite nanofibrous membrane to improve the affinity between microorganisms and hydrophobic substrates.

(4) As an environmentally friendly, corrosion-resistant, highly biocompatible, easily recyclable, non-toxic to cells and the environment, which can provide continuous repair and cost-effective composite nanofibrous membranes.

The composite nanofiber membrane manufactured by the invention not only has excellent biocompatibility, excellent mechanical strength and corrosion resistance, but also is non-toxic, harmless, recyclable and has considerable cost-effectiveness. It can adapt to various adverse environments, has stable composition and structure, can be repaired for a long time and can be recycled and reused, which saves resources and reduces costs to a considerable extent. After it is put into the polluted environment, it can exert its lipophilic and hydrophobic properties, quickly absorb the oil slick in the water environment, inhibit the continuous diffusion of leaked petroleum hydrocarbons, reduce the hydrocarbons in the water environment, and provide a relatively favorable metabolic environment for microorganisms . In addition, its strong adsorption force can quickly adsorb free bacterial cells on the membrane to form a dense biofilm, which can not only resist the adverse external environment, reduce the loss of bacterial cells during the repair process, but also help promote cell migration and nutrition. allocation. Finally, the affinity between bacterial cells and hydrophobic petroleum hydrocarbon pollutants is enhanced, and the efficiency of treating hydrocarbon pollutants is improved. Therefore, the composite nanofibrous membrane used for immobilized microorganisms to remediate diesel polluted water described in the present invention is expected to become a new and efficient biological carrier material for remediating polluted water.

Description of drawings

Fig. 1 is the transmission electron microscope picture of the acicular nano-hydroxyapatite (nHA) used in the present invention; the scale bar in A is 2 μm, and the scale bar in B is 1 μm.

Fig. 2 is the scanning electron micrograph of the nanofibrous film prepared in embodiment 1～6; Wherein, A is the scanning electron microscopic picture of the nanofiber film prepared in embodiment 1, B is the scanning electron micrograph of the nanofibrous film prepared in embodiment 2 Microscope image, C is the scanning electron microscope image of the nanofiber membrane prepared in embodiment 3, the scanning electron microscope image of the nanofiber membrane prepared in D embodiment 4, E is the scanning electron microscope image of the nanofiber membrane prepared in embodiment 5, F is a scanning electron micrograph of the nanofiber membrane prepared in Example 6; the scale bar in A to E is 30 μm, and the scale bar in F is 20 μm.

Fig. 3 is the scanning electron micrograph of the composite nanofiber membrane prepared in embodiment 7～9; Wherein, A is the scanning electron microscope diagram of the composite nanofiber membrane (TPU/0.5HA) prepared in embodiment 7, B is embodiment 8 is the scanning electron microscope image of the composite nanofiber membrane (TPU/1HA) prepared, and C is the scanning electron microscope image of the composite nanofiber membrane (TPU/1.5HA) prepared in Example 9; the scale bar is 20 μm.

Fig. 4 is the immobilized microbial effect drawing of the nanofiber membrane or the composite nanofiber membrane prepared in Examples 6-9; Wherein, A～D is the fiber membrane (TPU) of embodiment 6, the fiber membrane of embodiment 7 (TPU/0.5HA ), Example 8 fiber membrane (TPU/1HA) and embodiment 9 fiber membrane (TPU/1.5HA) load situation, a～d is its corresponding enlarged picture successively; The scale in A～D is 30 μ m, a～d The middle scale bar is 5 μm.

Fig. 5 is the XRD spectrum of the nanofiber membrane or composite nanofiber membrane prepared in Examples 6-9, hydrophobicity, mechanical property and the characterization figure of immobilized microorganism remediation performance of diesel oil polluted water; Wherein, A is XRD spectrum, B is water Contact angle diagram, C is the tensile curve, D is the characteristic diagram of immobilized microorganism remediation of polluted water.

Fig. 6 is the scanning electron micrograph of the nanofiber film prepared in Example 6 and Comparative Examples 1-2; wherein, A is the scanning electron micrograph of the nanofibrous film prepared in Comparative Example 1, and B is the nanofiber prepared in Example 6 The scanning electron microscope image of the film, C is the scanning electron microscope image of the nanofiber membrane prepared in Comparative Example 2; the scale bar is 10 μm.

Detailed ways

In the present invention, the thermoplastic polyurethane (TPU) can be prepared by known methods in the art, or can be obtained commercially. Specifically, the thermoplastic polyurethane used in the embodiment of the present invention is a polyester thermoplastic polyurethane purchased from China Taiwan Risheng Chemical Co., Ltd., with a product number of BTE-75A and a weight average molecular weight of 80,000.

In the present invention, the nano-hydroxyapatite (nHA) can be prepared by known methods in the art, and can also be obtained commercially. Specifically, the nano-hydroxyapatite used in the embodiment of the present invention is needle-shaped, 90-100nm long and 15-25nm wide, which was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a product number of H106378-25g. Figure 1 is a transmission electron microscope picture of nano-hydroxyapatite used in the embodiment of the present invention. The results show that nHA is easy to aggregate, but its needle-like structure and size less than 100nm can still be seen from the picture.

In the present invention, the formula of the MSM medium is: Na ₂ HPO ₄ 2H ₂ O 3.5g; KH ₂ PO ₄ 1.0g, (NH ₄ ) ₂ SO ₄ 0.5g, MgCl ₂ 6H ₂ O 0.1g, CaCl ₂ 0.046g, Trace Element Solution SL-4 1.0mL, deionized water 1000mL; pH=7.25. Among them, the formula of Trace Element Solution SL-4 is: ethylenediaminetetraacetic acid (EDTA) 0.500g, FeSO ₄ ·7H ₂ O 0.200g, Trace Element Solution SL-6 100mL, deionized water 900mL. The formula of Trace Element Solution SL-6 is: ZnSO ₄ 7H ₂ O 0.100g; MnCl ₂ 4H ₂ O 0.030g, H ₃ BO ₃ 0.300g, CoCl ₂ 6H ₂ O 0.200g, CuCl ₂ 2H ₂ O0. 010g, NiCl ₂ ·6H ₂ O 0.020g, Na ₂ MoO ₄ ·2H ₂ O 0.030g, deionized water 1000mL; pH=3.4.

According to the present invention, a composite nanofibrous membrane for immobilized microorganisms to repair diesel-polluted water, its preparation method comprises the following steps:

(1) Add needle-shaped nano-hydroxyapatite to the solvent system composed of N,N-dimethylformamide and acetone, perform the first ultrasonic wave, then add polyester thermoplastic polyurethane, stir evenly, and carry out the second Secondary ultrasonication, static defoaming, to obtain a uniform spinning solution S3;

(2) Spinning the spinning solution S3 by electrospinning to obtain a TPU/nHA composite nanofiber film;

(3) After drying the TPU/nHA composite nanofiber membrane, obtain a composite nanofiber membrane for immobilized microorganisms to repair diesel-polluted water;

Wherein, in step (1), the volume ratio of N,N-dimethylformamide and acetone in the solvent system is 3:1, and the ratio of the needle-shaped nano-hydroxyapatite:solvent system is 0.5-1.5 : 100W/V, the first ultrasonic treatment is 10-30min (preferably 20-30min) at 25°C, 40KHz, 650W, and the stirring is at 120r/min, 30°C for 5-10h (preferably 6-8h), the second ultrasonic treatment is ultrasonic treatment at 25°C, 40KHz, 650W for 10-30min (preferably 10-15min), and the standing defoaming is standing at 25°C for 5 minutes ~15min (preferably 10~15min) to defoam, the spinning solution S3 contains polyester thermoplastic polyurethane 22%W/V;

In step (2), the spinning process conditions are: spinning voltage 10-20kv (preferably 17-20kv), spinning distance 10-20cm (preferably 15-20cm), ambient temperature 25±5°C, humidity 40 -45%;

In step (3), the post-drying treatment is to dry in a vacuum oven at -0.085 MPa and 65°C for 5-10 days (preferably 7-10 days) to evaporate all the solvents.

The invention optimizes the mass concentration of TPU in the process of electrospinning TPU nanofiber membrane, optimizes the microstructure of the fiber membrane to the greatest extent, makes it have better mechanics and biocompatibility, and then maximizes its immobilized microbial cells effect and the efficiency of remediation of polluted water. During the process of nHA blending modified TPU nanofiber membrane, due to the excellent adsorption and biocompatibility of nHA, the nHA exposed on the surface of the fiber adds a large number of adsorption sites for the composite membrane, making the fiber membrane more effectively immobilized free cells in the environment. Based on the optimization of the mass concentration of nHA, the effect of the joint action of nHA and the fiber membrane is maximized, and the immobilization and repair effect of the composite membrane are improved.

In order to further understand the present invention, a composite nanofiber membrane and its preparation method for immobilized microorganism remediation of diesel-polluted water provided by the present invention will be described below in conjunction with examples. The scope of protection of the present invention is not limited by the following examples.

Example 1

A nanofibrous membrane for immobilized microorganisms to repair diesel-polluted water, the preparation method of which comprises the following steps:

(1) Mix N,N-dimethylformamide and acetone uniformly at a volume ratio of 3:1 to prepare a solvent system, and then add polyester thermoplastic polyurethane to the solvent system, at a speed of 120r/min and a temperature of 30 Stirring at ℃ for 8 hours to obtain a uniform and transparent spinning solution S1, the spinning solution S1 contains polyester thermoplastic polyurethane 12% W/V;

(2) Under the conditions of 25°C, 40KHz, and 650W, ultrasonically treat the spinning solution S1 for 15 minutes, then let it stand at 25°C for 10 minutes to defoam, and naturally cool to room temperature to obtain the spinning solution S2, which is ready for use;

(3) The spinning solution S2 is spun by electrospinning, and the spinning voltage is controlled to be 18kv, the spinning distance is 15cm, the ambient temperature is 30°C, and the humidity is 45%, to obtain a thermoplastic polyurethane nanofiber film (TPU nanofiber film );

(4) Put the TPU nanofiber membrane in a vacuum oven, dry it at -0.085MPa, 65°C for 7 days to volatilize all the solvents, and cool it to room temperature naturally to obtain nano Fiber membrane.

Example 2

The preparation of the nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 1, except that the spinning solution S1 contained 14% W/V of polyester thermoplastic polyurethane.

Example 3

The preparation of the nanofibrous membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 1, except that the spinning solution S1 contained 16% W/V of polyester thermoplastic polyurethane.

Example 4

The preparation of the nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 1, except that the spinning solution S1 contained 18% W/V of polyester thermoplastic polyurethane.

Example 5

The preparation of the nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 1, except that the spinning solution S1 contained 20% W/V of polyester thermoplastic polyurethane.

Example 6

The preparation of the nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 1, except that the spinning solution S1 contained 22% W/V of polyester thermoplastic polyurethane.

Fig. 2 is a scanning electron microscope image of the nanofibrous membranes prepared in Examples 1-6 and used for immobilized microorganisms to remediate diesel-polluted water. It can be seen from the figure that when the spinning solution S1 contains 22% polyester thermoplastic polyurethane, the microscopic appearance of the nanofiber membrane is the best, and the fiber shape is uniform; the spinning solution S1 contains polyester thermoplastic polyurethane 12% or At 14% or 16%, there are a lot of beads in the nanofiber membrane; although when the spinning solution S1 contains polyester thermoplastic polyurethane 18% or 20%, the nanofiber membrane beads are significantly reduced, but it is obvious that the spinning solution S1 The fiber shape of the nanofibrous membrane is the best when the polyester thermoplastic polyurethane is contained in 22%.

Example 7

Preparation of composite nanofibrous membranes for immobilized microorganisms to remediate diesel-polluted water, the steps are as follows:

(1) Mix N,N-dimethylformamide and acetone uniformly at a volume ratio of 3:1 to prepare a solvent system, and then add needle-shaped nano-hydroxyapatite to the solvent system, and the needle-shaped nano-hydroxyapatite The ratio of apatite:solvent system is 0.5:100W/V, ultrasonic treatment at 25°C, 40KHz, 650W for 25min, then adding polyester thermoplastic polyurethane, stirring at 120r/min, temperature 30°C for 8h, Ultrasonic treatment was performed at 25°C, 40KHz, and 650W for 15 minutes, then stood at 25°C for 10 minutes to defoam, and cooled naturally to room temperature to obtain a uniform spinning solution S3. The polyester-type thermoplastic polyurethane in the spinning solution S3 The mass concentration is 22%;

(2) The spinning solution S3 is spun by electrospinning, the spinning voltage is 18kv, the spinning distance is 15cm, the ambient temperature is 30°C, and the humidity is 45%, to obtain thermoplastic polyurethane/nano hydroxyapatite Composite nanofiber membrane (TPU/nHA composite nanofiber membrane);

(3) Put the TPU/nHA composite nanofiber membrane in a vacuum oven, dry it at -0.085MPa and 65°C for 7 days to evaporate all the solvents, and cool it down to room temperature naturally to obtain an immobilized microorganism for repairing diesel pollution. Composite nanofiber membranes for water.

Example 8

The preparation of a composite nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 7, except that the ratio of needle-shaped nano-hydroxyapatite:solvent system was 1:100W/V.

Example 9

The preparation of a composite nanofiber membrane for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 7, except that the ratio of needle-shaped nano-hydroxyapatite:solvent system was 1.5:100W/V.

Fig. 3 is a scanning electron micrograph of the composite nanofibrous membrane prepared in Examples 7-9 for immobilized microorganisms to remediate diesel-polluted water. Wherein, Fig. 3 A is the electron micrograph of the composite nanofiber membrane prepared in Example 7, and it can be seen that the nHA particles introduced on the surface of its fiber are less; There are many nHA particles; FIG. 3C is an electron micrograph of the composite nanofibrous membrane prepared in Example 9, and it can be seen that the surface-bound nHA particles are the most.

The nanofiber membranes or composite nanofiber membranes prepared in Examples 6 to 9 with a size of 1cm × 1cm for immobilized microorganisms to remediate diesel-polluted water were respectively placed in 20mL inorganic salt medium, and 1mL _OD600 of 0.2 wax was added thereto. Bacillus cereus (Bacillus cereus) LY-1 bacterium liquid, and according to the final concentration of 0.3% w/v, add the diesel oil that is filtered and sterilized as the sole carbon source, and cultivate it in a rotary shaker (100rpm) at 40±1°C for 3 days to obtain Immobilized fibrous membrane. Take the immobilized fiber membrane out of the inorganic salt medium, rinse it with normal saline three times to remove impurities, then soak it in 4% glutaraldehyde solution and place it in a refrigerator at 4°C for 30 minutes, then rinse it with sterile normal saline 3 times, then freeze in -20°C refrigerator for 24h, and then place the frozen immobilized fiber membrane in a freeze dryer (-65°C, vacuum 20Pa) to dry for 24h, and finally take out the sample and spray it with gold and use SEM observe. The results are shown in Figure 4. Compared with the nanofibrous membrane prepared in Example 6, the composite nanofibrous membranes prepared in Examples 7-9 showed better immobilization effects; among them, the composite nanofibrous membrane prepared in Example 9 A dense biofilm is formed on the surface, and the immobilization effect is the best.

5A to 5C are XRD diagrams, water contact angle diagrams and tensile property diagrams of the nanofiber membranes or composite nanofiber membranes prepared in Examples 6-9. The results of XRD patterns showed that nHA particles were successfully introduced into the composite nanofibrous membrane. The water contact angle diagram shows that with the increase of nHA content in the spinning solution S3, the hydrophilicity of the membrane increases, thereby improving the biocompatibility of the membrane; although the corresponding lipophilicity decreases slightly, it is not obvious, so it still has Considerable oil absorption effect. The tensile property diagram shows that the increase of nHA content in the spinning solution S3 reduces the mechanical properties of the membrane, but the mechanical properties of the composite nanofiber membrane when the ratio of needle-like nano-hydroxyapatite:solvent system is 1.5:100W/V Still good enough for a variety of environments.

The nanofiber membranes or composite nanofiber membranes prepared in Examples 6 to 9 with a size of 1cm × 1cm for immobilized microorganisms to remediate diesel-polluted water were respectively placed in 20mL inorganic salt medium, and 1mL _OD600 of 0.2 wax was added thereto. Bacillus cereus (Bacillus cereus) LY-1 bacterial liquid, and filter-sterilized diesel oil was added as the sole carbon source at a final concentration of 0.3% w/v, and cultured in a rotary shaker (100 rpm) at 40±1°C for 3 days. Only adding bacterial solution without fiber membrane was used as planktonic cells, and no bacterial solution or fiber membrane was added as sterile control (sterile control). Hydrocarbons and their derivatives were extracted from the culture medium after 3 days of degradation using high-resolution GC-FID analysis. The extraction process and sample processing are as follows: use petroleum ether (60-90) as the extraction solvent at room temperature for extraction. All measurements were performed on an Agilent 7890B equipped with a split/splitless SSL injector and FID detector. The furnace temperature of the GC part is 40°C, maintained for 3 minutes, heated to 275°C at a rate of 12°C/min and maintained for 8 minutes. 1 μL of sample was injected at 300°C, splitless. The chromatographic column is Agilent 19091J-413 HP-5, 30m×320μm×0.25μm. The nitrogen carrier gas was maintained at a constant flow rate of 1.5 ml/min. From the repair performance characterization diagram (Figure 5D), it can be seen that compared with the repair effect of free cells, the nanofiber membrane-immobilized microorganisms and the composite nanofiber membrane-immobilized microorganism treatment groups showed a better diesel degradation rate, and the diesel oil degradation rate prepared in Example 6 The diesel oil degradation rate of microorganisms immobilized on nanofiber membranes increased by 4.33 percentage points compared with free cells; with the increase of nHA content, the diesel fuel degradation rate of microorganisms immobilized on composite nanofiber membranes gradually increased. Among them, the composite nanofibers prepared in Example 9 The diesel degradation rate of membrane-immobilized microorganisms increased by 20.64 percentage points compared with free cells.

Comparative example 1

The preparation of nanofiber membranes for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 6, except that the spinning voltage was 10 kv and the spinning distance was 15 cm when spinning the spinning solution S2.

Comparative example 2

The preparation of nanofiber membranes for immobilized microorganisms to remediate diesel-polluted water was basically the same as in Example 6, except that the spinning solution S2 was spun with a spinning voltage of 18kv and a spinning distance of 10cm.

The microscopic morphology of the nanofibrous membranes prepared in Example 6 and Comparative Examples 1-2 was observed. As can be seen from Figure 6, when other conditions are constant, reducing the spinning voltage and reducing the spinning distance are all unfavorable to the fiber membrane morphology; the fiber thickness in the nanofiber membrane made in Comparative Example 1 is not uniform and accompanied by the appearance of beads; Although the nanofibrous membrane prepared in Example 2 has no beads, the fiber diameter is too thick and accompanied by bonding; the nanofibrous membrane prepared in Example 6 has uniform fiber thickness and better fiber shape.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (10)

1. A preparation method of a composite nanofiber membrane for treating diesel polluted water by immobilized microorganisms is characterized by comprising the following steps of: the method comprises the following steps:

(1) Adding nano hydroxyapatite into a solvent system consisting of N, N-dimethylformamide and acetone, performing ultrasonic treatment for 10-30 min, adding thermoplastic polyurethane, stirring for 5-10 h at the speed of 120r/min and the temperature of 30 ℃, performing ultrasonic treatment for 10-30 min again, and standing for 5-15 min to remove foam, so as to obtain uniform spinning solution S3;

(2) Spinning the spinning solution S3 by adopting an electrostatic spinning method to obtain a thermoplastic polyurethane/nano hydroxyapatite composite nanofiber membrane;

(3) And (3) drying and post-treating the thermoplastic polyurethane/nano hydroxyapatite composite nanofiber membrane to obtain the composite nanofiber membrane for treating diesel polluted water by immobilized microorganisms.

2. The method of manufacturing according to claim 1, characterized in that: in the step (1), the solvent system is prepared from N, N-dimethylformamide and acetone according to a volume ratio of 3: 1.

3. The method of manufacturing according to claim 1, characterized in that: in step (1), the nano hydroxyapatite powder: the proportion of the solvent system is 0.5-1.5: 100W/V.

4. A method of preparation according to claim 3, characterized in that: in step (1), the nano hydroxyapatite powder: the ratio of the solvent system was 1.5:100W/V.

5. The method of manufacturing according to claim 1, characterized in that: in the step (1), the mass fraction of the thermoplastic polyurethane in the spinning solution S3 is 8% -22%.

6. The method of manufacturing according to claim 5, wherein: in the step (1), the mass fraction of the thermoplastic polyurethane in the spinning solution S3 is 22%.

7. The method of manufacturing according to claim 1, characterized in that: in the step (2), the spinning process conditions are as follows: the spinning voltage is 10-20 kv, and the spinning distance is 10-20 cm.

8. The method of manufacturing according to claim 1, characterized in that: in the step (3), the process conditions of the drying post-treatment are as follows: and drying for 5-10 days in a vacuum oven under the condition of minus 0.085MPa and 65 ℃.

9. A composite nanofiber membrane made by the method of claim 1.

10. Use of the composite nanofiber membrane of claim 9 for repairing diesel contaminated water.