Fiber membrane for synchronously separating and degrading oily wastewater as well as preparation method and application of fiber membrane

Abstract

The invention discloses a fibrous membrane for synchronously separating and degrading oily wastewater as well as a preparation method and application of the fibrous membrane. The fiber membrane is prepared by taking a polymer matrix and a photocatalytic medium dispersed in the polymer matrix as raw materials; the polymer matrix is polystyrene, and the photocatalytic medium is graphite phase carbon nitride (g-C3N4). The preparation method comprises the following steps: dissolving polystyrene in an organic solvent to obtain a polystyrene solution; the preparation method comprises the following steps: dispersing g-C3N4 in an organic solvent to obtain a g-C3N4 suspension; and mixing the solution and the suspension to prepare a spinning solution, and performing electrostatic spinning to prepare the fibrous membrane for synchronously separating and degrading the oily wastewater. The fiber membrane disclosed by the invention can efficiently separate an oil-water mixture and an oil-water emulsion, can effectively degrade dyes and antibiotics in water, can further realize separation of the oil-water emulsion and degradation of pollutants in the oil-water emulsion, has the advantages of low cost, simple preparation process and application method, wide applicability and the like, and is suitable for industrial production. The method has application value in the field of treatment and purification of wastewater containing oil and organic pollutants and having complex composition.

Description

Technical Field

[0001] The present application relates to the technical field of oil-water separation, and in particular to a fiber membrane for synchronously separating and degrading oily wastewater, and a preparation method and application thereof. Background Art

[0002] The efficient separation and treatment of industrial oily wastewater is of great significance for environmental protection and human health. Compared with traditional oil-water separation technologies (such as skimming, flotation, centrifugation, etc.), membrane separation technology with special wettability has the advantages of energy saving, environmental protection, and high efficiency, and has obvious technical advantages in the field of oily wastewater treatment and separation. However, the composition of oily wastewater discharged from actual industry is complex. In addition to oil, it often contains organic pollutants such as dyes and antibiotics. Due to the toxicity, non-biodegradability, and carcinogenicity of these organic pollutants, they pose a serious threat to the ecological environment. However, most of the oil-water separation membranes currently studied can only separate oil and water, but cannot remove organic pollutants in water, and polluted water will continue to cause damage to the environment. Photocatalysis is an environmentally friendly and efficient water treatment technology. The degradation products of organic pollutants under photocatalysis are mainly environmentally friendly carbon dioxide and water, which can achieve water purification. Therefore, the development of membrane materials with both oil-water separation and photodegradation functions is very necessary to fundamentally solve the environmental pollution problem of industrial oily wastewater with complex composition and organic pollutants.

[0003] A titanium dioxide-loaded oily wastewater purification net membrane disclosed in Chinese patent CN102764536A can achieve oil-water separation of oily wastewater and degradation of pollutants in water, but because titanium dioxide can only produce photodegradation activity under ultraviolet light and has no light response under visible light, therefore, an ultraviolet light source needs to be used in the degradation process of the membrane, which leads to a relatively low utilization rate of solar energy, limiting its practical application. A multifunctional oil-water separation material disclosed in Chinese patent CN 110102083A and an oil-water separation net membrane with photocatalysis disclosed in CN 106186171A can both separate oil-water mixtures and make full use of sunlight, effectively degrade pollutants under visible light, and achieve separation and purification of wastewater containing oil and organic pollutants. However, the preparation process of the membrane in these technologies is relatively cumbersome or has high operating requirements, and separation and degradation need to be carried out separately in two steps when performing separation and purification, which is time-consuming and energy-consuming, and has high application costs. If separation and degradation can be completed in one step at the same time, the process will be reduced, which is conducive to reducing costs and reducing the difficulty of membrane application. At the same time, the above-mentioned existing technologies can only be used for the separation of oil-water mixtures, and the separation efficiency is low, and the separation and treatment of oil-water emulsions stabilized by surfactants are not discussed. In fact, most actual industrial oily wastewater exists in the form of oil-water emulsions. Compared with oil-water mixtures, oil-water emulsions are more stable and more difficult to separate. Therefore, it is more challenging to separate and purify oil-water emulsions containing organic pollutants. It is urgent to develop a new membrane material that has both visible light degradation function and high-efficiency separation capabilities for oil-water mixtures and oil-water emulsions.

[0004] Expanded polystyrene is widely used as a packaging material, food container material, insulation material, etc. Expanded polystyrene has stable chemical properties, and a large amount of waste is difficult to degrade in nature, which poses great environmental hazards. In particular, the microplastics formed by it pose a great threat to the ecological environment and human health. Polystyrene has excellent spinnability, and can be used to prepare fiber membranes with various functions and uses through mature electrospinning technology. Polystyrene materials have special surface wettability of hydrophobic / oleophilic, and electrospun membranes have large relative area and high porosity. Therefore, the use of polystyrene electrospinning membranes for oil-water separation is expected to achieve high flux and high separation efficiency. Graphitic carbon nitride (gC 3 N 4 ) can efficiently degrade organic pollutants (dyes, antibiotics, etc.) in water under visible light, and has attracted much attention in the field of photodegradation wastewater treatment.

[0005] In summary, the present invention utilizes electrospinning technology to 3 N 4By loading it into recycled polystyrene, it is expected to utilize low-cost plastic waste and simple preparation process to obtain a new membrane material that has the ability to separate oil-water mixtures and oil-water emulsions and has visible light degradation function. It has application potential in the separation and purification of actual industrial oily wastewater with complex composition. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a fiber membrane for synchronous separation and degradation of oily wastewater and a preparation method and application thereof, which overcomes the problems of complex preparation and application process, low separation efficiency, narrow application range, etc. of existing oily wastewater separation membranes.

[0007] On the one hand, the present invention discloses a fiber membrane for synchronous separation and degradation of oily wastewater, wherein the fiber membrane is a fiber membrane made of a polymer matrix and a photocatalytic medium dispersed in the polymer matrix as raw materials, wherein the polymer matrix is ​​polystyrene, and the photocatalytic medium is graphite phase carbon nitride (gC 3 N 4 ), the fiber membrane has a mesh structure composed of fibers interlaced with each other.

[0008] Optionally, the photocatalytic medium accounts for 10% to 60% of the weight of the polymer matrix.

[0009] Optionally, the fiber membrane has a thickness of 0.2 to 1.5 mm.

[0010] Optionally, the fiber diameter in the fiber membrane is 1 to 15 μm.

[0011] The synchronous separation and degradation of oily wastewater fiber membrane has lipophilic / hydrophobic surfaces, can achieve separation of oil-water mixtures and oil-water emulsions, and can degrade organic pollutants such as dyes and antibiotics in water under visible light.

[0012] On the other hand, the present invention also provides a method for preparing the fiber membrane for synchronous separation and degradation of oily wastewater, comprising the following steps: (1) dissolving polystyrene in an organic solvent to obtain a polystyrene solution; (2) gC 3 N 4 Dispersed in an organic solvent, gC 3 N 4 Suspension; (3) The polystyrene solution obtained in step (1) and the gC obtained in step (2) are mixed. 3 N 4 The suspensions are mixed to form a spinning solution, and a fiber membrane for synchronously separating and degrading oily wastewater is prepared by electrostatic spinning.

[0013] Optionally, in step (1), the polystyrene is obtained by recycling waste polystyrene foam, and the recycling step comprises: The waste polystyrene foam is crushed and dissolved in an organic solvent to obtain a solution, the solution is added to a precipitant, filtered, a precipitate is obtained, and vacuum dried to obtain polystyrene.

[0014] Optionally, the organic solvent in the recovery step is dichloromethane or chloroform. Optionally, the sedimentation agent is ethanol or water. Optionally, the process conditions of the vacuum drying are: drying temperature 50-80°C, drying time 6-12 hours.

[0015] Optionally, in step (2), the gC 3 N 4 The method comprises placing the urea in a muffle furnace, heating the temperature to 550°C at a heating rate of 5°C / min, and keeping the temperature for 4 hours.

[0016] Optionally, in step (1) and step (2), the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0017] Optionally, in step (3), the spinning solution concentration is 20-80 wt %. Preferably, the spinning solution concentration is 30-60 wt %.

[0018] Optionally, the electrospinning conditions are as follows: the positive voltage is 10-15 kV, the negative voltage is 2-5 kV, the syringe propulsion speed is 0.1-0.6 mm / min, the receiving distance is 15-30 cm, and the receiver speed is 4000-6000 r / h. Preferably, the electrospinning conditions are as follows: the positive voltage is 12-14 kV, the negative voltage is 2-4 kV, the syringe propulsion speed is 0.2-0.4 mm / min, the receiving distance is 15-25 cm, and the receiver speed is 4500-5500 r / h.

[0019] In a third aspect, the present application also provides an application of the fiber membrane for synchronous separation and degradation of oily wastewater in separation and purification of oily wastewater. The fiber membrane can achieve synchronous separation and degradation purification of oily wastewater. The oily wastewater is an oil-water mixture or an oil-in-water emulsion.

[0020] Compared with the prior art, the fiber membrane for synchronous separation and degradation of oily wastewater and its preparation method and application of the present application have at least the following technical effects: (1) The fiber membrane for simultaneous separation and degradation of oily wastewater of the present invention uses waste polystyrene foam and inexpensive urea as raw materials, and utilizes mature electrospinning preparation technology to convert gC 3 N 4By loading it into polystyrene fibers, a fiber membrane with both oil-water separation and photodegradation functions is obtained. The raw material cost is low, the preparation process is simple and mature, and it is suitable for large-scale industrial production.

[0021] (2) The fiber membrane for simultaneous separation and degradation of oily wastewater of the present invention can still maintain stable surface wettability (hydrophobic / oleophilic) in various harsh environments (strong acid, strong alkali, high salt, etc.), and can quickly and efficiently separate different types of oil-water mixtures and oil-water emulsions under gravity drive without pressurization, and can maintain high separation efficiency and flux after repeated use. At the same time, the membrane has excellent photocatalytic ability under visible light, and can separate oil-water emulsions and degrade organic pollutants in one step, overcoming the problems of step-by-step separation and complex degradation process in the prior art.

[0022] (3) The fiber membrane for simultaneous separation and degradation of oily wastewater of the present invention has the advantages of low cost, simple preparation process and application method, and wide applicability, and has application value in the field of wastewater treatment and purification with complex composition of oily and organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the infrared spectrum of the recycled polystyrene prepared in Example 1 of the present invention.

[0024] Figure 2 gC prepared in Example 2 of the present invention 3 N 4 X-ray diffraction spectrum of .

[0025] Figure 3 Sample photos of the fiber membrane for synchronous separation and degradation of oily wastewater (a) prepared in Example 3 of the present invention and the polystyrene fiber membrane (b) prepared in Comparative Example 1.

[0026] Figure 4 X-ray photoelectron spectrum comparison diagram (a) and N1s peak fitting diagram (b) of the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 of the present invention and the polystyrene fiber membrane prepared in Comparative Example 1.

[0027] Figure 5 The scanning electron microscope photographs and fiber diameter distribution diagrams (a), (b) and element distribution diagram (c) of the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 of the present invention, wherein (d) is the distribution diagram of the C element in the element distribution diagram, and (e) is the distribution diagram of the N element in the element distribution diagram.

[0028] Figure 6 The contact angle test results of oil in air (a) and water in air (b) for the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0029] Figure 7The contact angle test results of oil in air (a) and water in air (b) for the polystyrene fiber membrane prepared in Comparative Example 1 of the present invention.

[0030] Figure 8 The contact angle test results of water in air and oil in air of the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3 of the present invention after being immersed in aqueous solutions of different pH values ​​(a) and different salt solutions of 0.1 mol / L (b) for 24 h.

[0031] Fig. 9 The separation flux and separation efficiency of 10 cycle experiments of separating n-hexane-water mixture by the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0032] Fig.10 The separation flux and separation efficiency of different oil-water mixtures separated by the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 of the present invention.

[0033] Fig.11 These are photos of samples before and after separation and microscope photos of the experiment of separating n-hexane water-in-water emulsion using the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0034] Fig.12 The separation flux and separation efficiency of the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 of the present invention after 10 cycles of separation of n-hexane water emulsion.

[0035] Fig.13 The UV-visible absorption spectrum (a) and degradation curve (b) of methylene blue degradation by the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0036] Fig.14 The UV-visible absorption spectrum (a) and degradation curve (b) of tetracycline hydrochloride degradation by the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0037] Fig.15 Photographs of samples before and after separation and microscope photographs thereof for the one-step separation and degradation of n-hexane water-in-water emulsion containing organic pollutants by the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 of the present invention.

[0038] Fig.16 This is the UV-visible absorption spectra of the eluent after separation with and without illumination in an experiment of synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 of the present invention for one-step separation and degradation of n-hexane water-in-water emulsion containing organic pollutants. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application. Example 1

[0040] Recycling of waste polystyrene foam:

[0041] Weigh 1 g of discarded polystyrene foam plastic fragments and dissolve them in 20 mL of dichloromethane, precipitate them in ethanol, filter them, and vacuum dry them at 60 °C for 8 h to obtain recycled polystyrene.

[0042] Attached Figure 1 Infrared spectrum of the recycled polystyrene prepared in Example 1, 3060 and 3026 cm -1 The peaks at 2922 and 2850 cm-1 are attributed to the stretching vibration absorption of the CH bond on the benzene ring of polystyrene. -1 The peak at can be attributed to CH 2 The stretching vibration of the C-H bonds, 1601, 1493 and 1452 cm -1 The peak at can be attributed to the stretching vibration absorption of the polystyrene benzene ring skeleton. This result shows that recycled polystyrene is obtained by simple treatment of waste polystyrene foam. Example 2

[0043] C 3 N 4 Preparation: Weigh 20 g of urea and spread it in a crucible, put it in a muffle furnace, set the heating rate to 5 °C / min, heat it to 550 °C, keep it warm for 4 h, cool it naturally to room temperature and take it out to obtain gC 3 N 4 .

[0044] Attached Figure 2 gC prepared in Example 2 3 N 4 The X-ray diffraction spectrum of the gC 3 N 4 (100) and (002) crystal planes, which confirms that gC was successfully prepared by thermal decomposition of urea. 3 N 4 . Example 3

[0045] Preparation of fiber membrane for simultaneous separation and degradation of oily wastewater:

[0046] 3 g of the recovered polystyrene obtained in Example 1 was dissolved in 6 mL of N,N-dimethylformamide to prepare a polystyrene solution. 1.2 g of the gC obtained in Example 2 was added. 3 N 4 Dispersed in 3 mL N,N-dimethylformamide, gC 3 N 4 The polystyrene solution prepared above and gC 3 N 4 The suspension was fully mixed to obtain a uniform spinning solution. The spinning solution was injected into the spinneret and spun using an electrospinning machine to obtain a fiber membrane for synchronous separation and degradation of oily wastewater. Spinning conditions: positive voltage of 12 kV, negative voltage of 2 kV, syringe advancement speed of 0.3 mm / min, receiving distance of 18 cm, and receiver speed of 4800 r / h. Comparative Example 1

[0047] Preparation of polystyrene fiber membrane:

[0048] Compared with Example 3, the difference is that gC is not added to the spinning solution. 3 N 4 , the rest is the same as Example 3. Example 4

[0049] Characterization of fiber membrane for simultaneous separation and degradation of oily wastewater:

[0050] Attached Figure 3 (a) and (b) are sample photos of the fiber membrane for synchronous separation and degradation of oily wastewater prepared in Example 3 and the polystyrene fiber membrane prepared in Comparative Example 1. The polystyrene fiber membrane is nearly white in appearance, while the fiber membrane for synchronous separation and degradation of oily wastewater is slightly yellowish. The fibers in both membranes are uniform and dense. Figure 4 (a) is a comparison of the X-ray photoelectron spectra of the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3 and the polystyrene fiber membrane prepared in Comparative Example 1. The oxygen peaks in the two membranes may come from the air or water adsorbed on the membrane surface. Compared with the polystyrene fiber membrane, the fiber membrane for simultaneous separation and degradation of oily wastewater has a nitrogen peak. The peaks at 397.7, 398.8 and 400.1 eV after fitting can be attributed to gC 3 N 4 CN = C, N-(C) 3 and CNH bonds (with Figure 4 (b)). Figure 5The scanning electron microscope photo and fiber diameter distribution diagram and element distribution diagram of the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3. It can be seen from the figure that the fibers are intertwined to form a network structure, the fiber diameter is mainly 2~6 μm, the fiber surface is rough, and nitrogen is evenly distributed on the fiber. The above results confirm that gC 3 N 4 It was successfully loaded into polystyrene fibers. Application Example 1

[0051] Surface wettability of fiber membrane for simultaneous separation and degradation of oily wastewater:

[0052] Attached Figure 6 The contact angle test results of the fiber membrane for simultaneous separation and degradation of oily wastewater prepared in Example 3 show that the contact angle of oil (n-hexane) in air is 0°, and the contact angle of water in air is 124.2°. Figure 7 The contact angle test results of the polystyrene fiber membrane prepared in Comparative Example 1 show that the contact angle of oil (n-hexane) in air is 0°, and the contact angle of water in air is 118.7°. These results show that gC 3 N 4 The loading has little effect on the surface wettability of the membrane, and the fiber membrane for simultaneous separation and degradation of oily wastewater maintains the excellent hydrophobicity / lipophilicity of the polystyrene fiber membrane itself. Figure 8 The contact angle test results of water in air and oil in air for the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 after being immersed in aqueous solutions of different pH values ​​or different salt solutions of 0.1 mol / L for 24 h showed that the membrane maintained stable hydrophobicity / lipophilicity, which is conducive to the application of the membrane in complex actual separation environments of strong acid, strong alkali or high salt. Application Example 2

[0053] Separation of oil-water mixture:

[0054] 40 mL of oil (n-hexane) and 40 mL of deionized water colored with methylene blue were measured and mixed to prepare an oil-water mixture. The synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 was used for separation under gravity drive, that is, the fiber membrane was placed on the stainless steel filter screen of the mobile phase filter as a filter layer, and then the n-hexane-water mixture prepared above was slowly poured into the filter cup of the filter. Because the membrane has lipophilic / hydrophobic properties, n-hexane quickly passes through the membrane, but water is retained. According to the formula η = m 1 / m 0 ×100% (where m 0 and m 1are the mass of oil before and after separation (g) and the formula F = V / At (in V is the volume of oil permeating through the membrane (L), A is the effective separation area of ​​the membrane (m 2 ), t is the separation time (h)). The oil separation flux calculated based on the experimental results is as high as 9589.9 L·m -2 ·h -1 The separation efficiency can reach 99.5%, and the separation flux is still 8700.0 L·m after 10 cycles. -2 ·h -1 Above, the separation efficiency is still above 99.2% (attached Fig. 9 ), which shows that the membrane can efficiently separate n-hexane-water mixture and has excellent recyclability. In addition, the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 also exhibits excellent separation ability for other different oil-water mixtures (such as cyclohexane-water, petroleum ether-water, n-octane-water, etc.) under gravity drive (see Appendix Fig.10 ), the separation flux was higher than 9300.0 L·m -2 ·h -1 The separation efficiency was higher than 99.3%. The above results confirm that the synchronous separation and degradation of oily wastewater fiber membrane prepared by the present invention can efficiently separate a variety of different oil-water mixtures. Application Example 3

[0055] Separation of water-in-oil emulsions:

[0056] Weigh 10 mg of Span 80 and add it to 99 mL of oil (n-hexane), then add 1 mL of deionized water to the above solution, and stir thoroughly to obtain an oil-in-water emulsion. The oil-containing wastewater was separated using the fiber membrane prepared in Example 3 for simultaneous separation and degradation, that is, the fiber membrane was placed on the stainless steel filter screen of the mobile phase filter as a filter layer, and then the above-prepared oil-in-water emulsion was slowly poured into the filter cup of the filter. The results are shown in the attached figure. Fig.11 As shown in the figure, the oil is in an opaque emulsion before separation and becomes a clear and transparent oil after separation. The oil separation flux calculated based on the experimental results is 4951.2 L·m -2 ·h -1 The separation efficiency reached 99.7%, and the separation flux remained at 3700.0 L·m after 10 cycles. -2 ·h -1 Above, the separation efficiency is still above 99.1% (attached Fig.12). This result confirms that the synchronous separation and degradation of oily wastewater fiber membrane prepared by the present invention can not only efficiently separate oil-water mixtures, but also effectively separate surfactant-stabilized oil-in-water emulsions that are relatively difficult to separate, and has excellent recycling performance, and has application potential in the treatment of wastewater containing oil emulsions. Application Example 4

[0057] Degradation dyes:

[0058] Methylene blue was used to simulate dye pollutants, and a methylene blue aqueous solution with a concentration of 10 mg / L was prepared. 100 mg of the synchronous separation and degradation fiber membrane for oil-containing wastewater prepared in Example 3 was added thereto. A xenon lamp (300 W, >400 nm) was used to provide a visible light source, and the light source was 10 cm away from the surface of the methylene blue solution. The methylene blue solution was placed in the dark for 30 min to reach adsorption-desorption equilibrium, and then placed under a xenon lamp. The xenon lamp was turned on for a degradation experiment. 3 mL of solution samples were collected at regular intervals, and the UV-visible absorption spectrum of the samples was measured using a UV-visible spectrophotometer. The results are shown in the attached figure. Fig.13 As shown in (a), with the extension of illumination time, the absorption peak of methylene blue (monitoring wavelength is 663 nm) gradually weakens, and the sample gradually changes from dark blue to colorless. The photocatalytic degradation rate can be expressed by the formula η=(1- c t / c 0 )×100%, where c t is the concentration of methylene blue in the solution sample at illumination time t (mg / L), c 0 is the initial concentration of methylene blue solution (mg / L). Fig.13 The test results of (b) show that the degradation rate of methylene blue is 52.3% after 1 h of illumination, and the degradation rate reaches 95.8% after 3.5 h of illumination. Application Example 5

[0059] Degradation of antibiotics:

[0060] Tetracycline hydrochloride was used to simulate antibiotic pollutants, and a tetracycline hydrochloride aqueous solution with a concentration of 15 mg / L was prepared. According to the above methylene blue degradation experimental method, the synchronous separation and degradation of oily wastewater fiber membrane prepared in Example 3 was used to perform a degradation experiment on tetracycline hydrochloride. Fig.14 As can be seen from the results of (a), with the extension of illumination time, the absorption peak of tetracycline hydrochloride (monitoring wavelength is 356 nm) gradually weakens. Fig.14 The test results of (b) show that the degradation rate of tetracycline hydrochloride is 50.5% after 2 h of illumination, and the degradation rate reaches 89.8% after 5 h of illumination.

[0061] The above results confirm that the fiber membrane for synchronous separation and degradation of oily wastewater prepared by the present invention can effectively degrade dyes and antibiotics in water, and can be used for purification of wastewater containing the above organic pollutants. Application Example 6

[0062] One-step separation and degradation of oil-water emulsion:

[0063] Methylene blue and tetracycline hydrochloride were used to simulate organic pollutants in water, and an oil-in-water emulsion containing methylene blue and tetracycline hydrochloride was prepared. The fiber membrane for synchronous separation and degradation of oil-containing wastewater prepared in Example 3 was used to separate and degrade it in one step. The specific operation steps are as follows: first, an aqueous solution containing methylene blue and tetracycline hydrochloride was prepared, wherein the concentration of methylene blue was 200 mg / L, and the concentration of tetracycline hydrochloride was 100 mg / L. 10 mg of Siban 80 was added to 99 mL of oil (n-hexane), and then 1 mL of the above-prepared aqueous solution containing methylene blue and tetracycline hydrochloride was added to the solution, and the oil-in-water emulsion containing organic pollutants was prepared after sufficient stirring. The fiber membrane was placed on the stainless steel filter screen of the mobile phase filter as a filter layer, and then a xenon lamp was placed directly above the filter cup of the mobile phase filter, and the xenon lamp was turned on. Then, the above-prepared oil-in-water emulsion containing organic pollutants was slowly poured into the filter cup to allow separation and degradation to proceed simultaneously. Attachment Fig.15 The sample photos before and after separation and the corresponding microscope photos are respectively. The oil-in-water emulsion containing organic pollutants is an opaque blue emulsion before separation, and a clear and transparent oil is obtained after separation. Combined with its microscope comparison photos, it can be confirmed that the fiber membrane can effectively separate the oil-in-water emulsion containing organic pollutants. The calculated separation flux is 4156.9 L·m -2 ·h -1 , the separation efficiency is 99.3%. Using the same experimental method as above, a comparative experiment was also conducted, in which the xenon lamp was not turned on, that is, the separation was performed without light. Fig.16 The UV-visible absorption spectra of the eluents of the residual water in the filter cup after the separation experiment under illumination and without illumination are shown respectively. It can be seen that the spectra of the eluent without illumination show strong absorption peaks of methylene blue (664 nm) and tetracycline hydrochloride (356 nm), while the spectra of the eluent under illumination have almost no absorption peaks. This result confirms that while the oil-in-water emulsion containing organic pollutants is separated, the pollutants in the water are degraded under the visible light of the xenon lamp. This confirms that the fiber membrane prepared by the present invention can achieve one-step separation and degradation of the oil-containing emulsion containing organic pollutants, which can overcome the cumbersome process of separation and degradation carried out in steps in most of the existing technologies.

[0064] The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. When the technical features in different embodiments are embodied in the same figure, it can be regarded that the figure also discloses the combination examples of the various embodiments involved.

[0065] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A fiber membrane for synchronous separation and degradation of oily wastewater, characterized in that: The fiber membrane is made of a polymer matrix and a photocatalytic medium dispersed in the polymer matrix as raw materials, the polymer matrix is ​​polystyrene, the photocatalytic medium is graphite phase carbon nitride (g-C3N4), and the fiber membrane has a network structure composed of interlaced fibers.

2. The fiber membrane for synchronous separation and degradation of oily wastewater according to claim 1 is characterized in that: The percentage of the photocatalytic medium to the weight of the polymer matrix is ​​10% to 60%.

3. The fiber membrane for synchronous separation and degradation of oily wastewater according to claim 1 is characterized in that: The thickness of the fiber membrane is 0.2-1.5 mm.

4. The fiber membrane for synchronous separation and degradation of oily wastewater according to claim 1 is characterized in that: The fiber diameter in the fiber membrane is 1 to 15 μm.

5. The method for preparing a fiber membrane for synchronous separation and degradation of oily wastewater according to any one of claims 1 to 4, characterized in that: The steps include: (1) dissolving polystyrene in an organic solvent to obtain a polystyrene solution; (2) dispersing g-C3N4 in an organic solvent to obtain a g-C3N4 suspension; (3) The polystyrene solution obtained in step (1) and the g-C3N4 suspension obtained in step (2) are mixed to form a spinning solution, and a fiber membrane for synchronous separation and degradation of oily wastewater is prepared by electrospinning.

6. The method for preparing a fiber membrane for synchronous separation and degradation of oily wastewater according to claim 5, characterized in that: In step (1) and step (2), the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

7. The method for preparing a fiber membrane for synchronous separation and degradation of oily wastewater according to claim 5, characterized in that: In step (3), the spinning solution concentration is 20-80 wt%.

8. The method for preparing a fiber membrane for synchronous separation and degradation of oily wastewater according to claim 5, characterized in that: In step (3), the electrospinning conditions are as follows: positive voltage is 10-15 kV, negative voltage is 2-5 kV, syringe advancement speed is 0.1-0.6 mm / min, receiving distance is 15-30 cm, and receiver rotation speed is 4000-6000 r / h.

9. The use of the fiber membrane for synchronous separation and degradation of oily wastewater according to claim 1 in separation and purification of oily wastewater, characterized in that: The fiber membrane can realize the synchronous separation and degradation purification of oily wastewater.

10. The use of the fiber membrane for synchronous separation and degradation of oily wastewater according to claim 9 in separation and purification of oily wastewater, characterized in that: The oily wastewater is an oil-water mixture or an oil-in-water emulsion.

Images