Modified mesh membrane and preparation method and application and device and method for treating oily wastewater

Abstract

The present invention relates to the field of modified materials, and in particular to an ultraviolet-induced modified mesh membrane, a preparation method and application thereof, and a device and method for treating oily wastewater. The method comprises: (1) melting polypropylene and an optional antioxidant to obtain a spinning solution, spinning the spinning solution to obtain polypropylene fibers; (2) using a modified functional monomer solution to graft-modify the polypropylene fibers under the action of ultraviolet light to obtain modified polypropylene fibers; (3) subjecting the modified polypropylene fibers to a web-forming treatment to obtain a three-dimensional porous modified mesh membrane.

Description

Technical Field

[0001] The invention relates to the field of modified materials, and in particular to a modified mesh membrane and a preparation method thereof, and an application device and a method for treating oily wastewater. Background Art

[0002] Oil pollution is extremely harmful to environmental protection and ecological balance. It is also extremely difficult to treat oily wastewater, with low efficiency and high cost. It is one of the most difficult industrial wastewaters to treat today. When treating oily wastewater based on membrane separation technology, it has the advantages of low energy consumption, high single-stage separation efficiency, flexible and simple operation process, low environmental pollution, and strong versatility. However, when treating oily wastewater, especially oil-water emulsion separation, there is a trade-off effect between flux and selectivity of traditional two-dimensional porous polymer separation membranes. It is difficult to have both high permeability and high selectivity. The flux decays quickly, the separation efficiency is not high, external driving pressure is required, it is easy to cause contamination, the types of oily wastewater to be treated are limited, and it is impossible to separate water-in-oil and oil-in-water emulsions at the same time. The essence of oil-water separation is an interface problem. By designing the special wettability of the material surface and taking advantage of the different residence times of the oil-water two-phase permeation behavior when the oil-water mixture contacts the surface of the composite material with special wettability, oil-water separation can be achieved without other auxiliary measures such as chemical agents. That is, the selective interception technology can be used to treat oily wastewater, which is the current cutting-edge technology for oil-water separation. Preliminary studies determined polypropylene as the basic raw material through screening of membrane materials, and then used appropriate methods to regulate and modify the oil-water wetting balance properties of the material surface to prepare the oil-water separation membrane.

[0003] Melt blending of hydrophilic polymers and polypropylene is a method for obtaining hydrophilicity and improving the oil-water wetting balance of fibers. Inorganic nanoparticles treated with coupling agents are added to the spinning solution to enhance fiber strength while also obtaining better hydrophilicity. These are all methods for modifying the composition of the spinning solution, but they will affect the overall performance of the material and require the spinning parameters to be readjusted accordingly. In addition, the existing polypropylene modification technology still has problems such as complex preparation process, harsh reaction conditions, poor repeatability, and low separation efficiency of the prepared membrane.

[0004] Therefore, it is necessary to develop a material with high separation efficiency. The preparation process of this material is simple, the conditions are mild, it is easy to operate, has good repeatability, low cost and energy consumption, and does not significantly affect the performance of the polypropylene material itself. When using this material for oil-water separation, it is safe and will not cause secondary pollution. Long-term operation can also ensure that the effluent indicators are stable and meet the standards. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a modified mesh membrane and a preparation method and an apparatus and method for using and treating oily wastewater. The preparation method has a simple process and does not significantly affect the performance of the main material. When the modified mesh membrane prepared by the method is used for oil-water separation, it has a high oil removal rate, does not cause secondary pollution, has a low treatment cost, and can remain effective for a long time.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a modified mesh membrane having an oil-water separation function, the method comprising:

[0007] (1) melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers;

[0008] (2) using a modified functional monomer solution to graft-modify the polypropylene fiber under the action of ultraviolet light to obtain a modified polypropylene fiber;

[0009] (3) The modified polypropylene fiber is subjected to a mesh processing to obtain a three-dimensional porous modified mesh membrane.

[0010] The second aspect of the present invention provides a modified omentum prepared by the method described above.

[0011] The third aspect of the present invention provides the use of the modified mesh membrane provided in the first aspect or the third aspect of the present invention in treating oily wastewater.

[0012] A fourth aspect of the present invention provides a treatment device for oily wastewater, which comprises, in order according to the direction of the material: a liquid storage tank and an oil-water separator;

[0013] Wherein, the liquid storage tank is used to store oily wastewater; the oil-water separator is filled with the modified mesh membrane as described above, which is used to separate oil from water;

[0014] The oil-water separator is also connected to a water production tank and an oil collection tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collection tank is used to receive the oil phase from the oil-water separator.

[0015] A fifth aspect of the present invention provides a method for treating oily wastewater. The method is carried out in the device as described above, and the method comprises: introducing the oily wastewater in the liquid storage tank into an oil-water separator to separate the oil and water.

[0016] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0017] 1. The modified mesh membrane prepared by the method of the present invention has a three-dimensional porous structure and can achieve a higher oil removal rate when used for oil-water separation.

[0018] 2. The preparation method provided by the present invention does not affect the strength and other properties of the main material. The preparation process is simple, the conditions are mild, the operation is easy, the repeatability is good, and the preparation cost and energy consumption are low.

[0019] 3. The oily wastewater treatment device provided by the present invention is small in size. When it is used for treating oily wastewater, the treatment process is safe and explosion-proof, the operating cost is low, no waste residue is generated, and long-term operation can ensure that the effluent indicators are stable and meet the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The invention provides a device for treating oily wastewater.

[0021] Description of Reference Numerals

[0022] 1-liquid storage tank; 2-sewage pump; 3-sewage tank; 4-flow regulating valve; 5-flow meter; 6-feed pump; 7-oil-water separator; 8-water production tank; 9-oil collecting tank. DETAILED DESCRIPTION

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] In the present invention, the "porosity" mentioned refers to the percentage of the volume of pores in the material to the total volume of the material.

[0025] In a first aspect, the present invention provides a method for preparing a modified mesh membrane with oil-water separation function, the method comprising:

[0026] (1) melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers;

[0027] (2) using a modified functional monomer solution to graft-modify the polypropylene fiber under the action of ultraviolet light to obtain a modified polypropylene fiber;

[0028] (3) The modified polypropylene fiber is subjected to a mesh processing to obtain a three-dimensional porous modified mesh membrane.

[0029] It is understood that whether to use an antioxidant in the preparation process can be selected according to the needs of the prepared product.

[0030] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, in step (1), according to the ASTMD1238-13 method, the melt index of the polypropylene at a temperature of 230°C and a load weight of 2.16 kg is 100-1000g / 10min. The inventors of the present invention have found in their research that the polypropylene in this melt index range has good fluidity, processability and mechanical properties of the prepared modified mesh, and can better cooperate with the modified functional monomer without significantly affecting the polypropylene main material, thereby obtaining a better modification effect and making the prepared modified mesh have a higher oil removal rate.

[0031] According to the present invention, in order to further make the modified mesh membrane effective for a long time, preferably, the antioxidant is selected from at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (which can be the commercially available antioxidant 1010), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (which can be the commercially available antioxidant 1076) and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (which can be the commercially available antioxidant 1790).

[0032] According to the present invention, the usage ratio of the polypropylene to the antioxidant is 9-99:1 by weight.

[0033] According to the present invention, preferably, the melting temperature is 175-210°C (for example, it can be 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C).

[0034] According to the present invention, in order to make the spinning solution more uniform, so that the oil-water separation efficiency of the prepared modified mesh is higher, preferably, stirring and degassing are performed after melting. More preferably, the stirring conditions include: stirring for 1-4 hours under the condition of nitrogen gas; the degassing conditions include: the temperature is 175-210°C, and the degassing is allowed to stand for 0.5-2 hours.

[0035] According to the present invention, preferably, before spinning, the spinning solution is subjected to solid-liquid separation to remove the unmelted solid phase therein. The method of the solid-liquid separation is not particularly limited, and is preferably filtration.

[0036] According to the present invention, preferably, the spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution.

[0037] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh, preferably, the spinning conditions make the diameter of the polypropylene fiber 10-40μm (for example, 10μm, 20μm, 30μm, 40μm).

[0038] According to the present invention, preferably, the extrusion temperature is 160-200°C. The device used for the extrusion is not particularly limited, and preferably the extrusion is carried out through a pipeline input screw extruder. For example, the spinning solution is input through a pipeline into a screw extruder for extrusion, and the pipeline temperature of the pipeline input screw extruder, i.e., the extrusion temperature, is 160-200°C.

[0039] According to the present invention, preferably, the spinning conditions include: the spinneret aperture is 0.05-2 mm, and the spinning temperature is 145-180°C.

[0040] According to the present invention, preferably, the stretching conditions include: airflow stretching, the airflow temperature is 120-150°C, and the stretching spinning speed is 100-500m / min. It can be understood that the spinning speed refers to the speed of forming fibers during the airflow stretching process.

[0041] According to the present invention, preferably, the cooling conditions include: using air cooling, the temperature of the air is 5-20°C.

[0042] According to the present invention, preferably, before the polypropylene fiber is grafted and modified, the method further comprises: washing and drying the polypropylene fiber in sequence. It can be understood that the washing is to remove impurities adsorbed on the surface of the polypropylene fiber, and the drying is to remove the liquid attached to the surface of the polypropylene fiber after washing. The washing and drying methods are not particularly limited, wherein the washing method is preferably to first immerse in ethanol for washing for 4-12 hours, and then wash with deionized water for at least 3 times, and the drying method is preferably to dry at 65-75°C for more than 24 hours.

[0043] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh, preferably, in step (2), the graft modification method includes: immersing the polypropylene fiber in a solution containing a first photoinitiator, subjecting the immersed polypropylene fiber to a first ultraviolet light treatment to obtain a polypropylene fiber whose surface is covered with the photoinitiator; immersing the polypropylene fiber whose surface is covered with the photoinitiator in a solution containing a modified functional monomer and a second photoinitiator, and modifying it under the action of a second ultraviolet light to obtain a modified polypropylene fiber.

[0044] The inventors of the present invention have found in their research that by immersing the polypropylene fiber in a solution containing a first photoinitiator, the photoinitiator can be adsorbed onto the surface of the polypropylene fiber through the intermolecular association between the polypropylene fiber and the photoinitiator. After the first ultraviolet light treatment, the light-sensitive photoinitiator decomposes to generate free radicals. The surface of the polypropylene fiber covered with the photoinitiator is actually covered with free radicals formed by the photoinitiator. Then, the polypropylene fiber covered with the photoinitiator on the surface is immersed in a solution containing a modified functional monomer and a second photoinitiator. Under the action of the second ultraviolet light, the second initiator also decomposes to generate free radicals. The free radicals formed by the first photoinitiator covering the surface of the polypropylene fiber and the free radicals formed by the second photoinitiator act together to initiate the free radical polymerization growth of the modified functional monomer on the surface of the polypropylene fiber, thereby obtaining a molecular chain directly connected to the surface of the polypropylene fiber. The inventors of the present invention have found in their research that the penetration ability of ultraviolet light is low, and the modification induced by ultraviolet light treatment can be more controlled on the surface of the material, and has less effect on the mechanical properties of the polypropylene body. Moreover, compared with the traditional existing methods, the method described above has obvious flexibility. By adjusting the amount of photoinitiator and the type and feed ratio of active monomers, the density of the grafted molecular chain, the type and length (i.e., molecular weight) of the grafted chain can be flexibly adjusted to achieve fine control of the oil-water wetting balance performance of the polypropylene surface.

[0045] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh, preferably, the mass ratio of the polypropylene modified fiber to the first photoinitiator in the solution containing the first photoinitiator is 100:5-10. The solvent in the solution of the first photoinitiator is not particularly limited, and is preferably one of ethanol, methanol, butanol or n-hexane.

[0046] According to the present invention, preferably, the soaking conditions include: time of 1-6 hours and temperature of 20-55°C.

[0047] It can be understood that after the soaked modified polypropylene fiber is taken out, it is first dried to remove the solvent therein, and then subjected to the first ultraviolet light treatment.

[0048] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, the conditions of the first ultraviolet light treatment include: in an inert gas atmosphere, the time is 0.5-3min, the temperature is 20-55°C, and the first ultraviolet light wavelength is 300-400nm. For example, at 25°C in a nitrogen atmosphere, ultraviolet light with a wavelength of 365nm is used for 2min to obtain a polypropylene fiber with a surface covered with a photoinitiator.

[0049] According to the present invention, in order to further improve the oil-water separation rate of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, the first photoinitiator is selected from at least one of 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone (which can be commercially available initiator 2959), 1,1'-[methylenebis(4,1-phenylene)]bis(2-hydroxy-2-methyl-1-propanone) (which can be commercially available initiator 127), 1-hydroxycyclohexyl phenyl ketone (which can be commercially available initiator 184), 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone (which can be commercially available initiator 907) and ethyl 2,4,6-trimethylbenzoylphenylphosphonate (which can be commercially available initiator TPO-L).

[0050] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, the mass ratio of the polypropylene fiber with a surface covered with a photoinitiator and the modified functional monomer in the solution containing the modified functional monomer and the second photoinitiator is 100:10-60.

[0051] According to the present invention, preferably, the mass ratio of the polypropylene fiber with the surface covered with the photoinitiator to the second photoinitiator in the solution containing the modified functional monomer and the second photoinitiator is 100:0.5-5. An aqueous solution containing the modified functional monomer and an ethanol or methanol solution containing the second photoinitiator can be prepared separately, and then the two are mixed, and the mixed homogeneous solution is ultrasonically degassed for 1-6 hours to obtain a solution containing the modified functional monomer and the second photoinitiator.

[0052] According to the present invention, preferably, the modified functional monomer is selected from at least one of acrylic acid, methacrylic acid, methyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, and N,N-dimethylacrylamide. It can be understood that the modified functional monomer as described above has better hydrophilicity, can better modify the oil-water wetting balance performance of the polypropylene surface, further improve the critical penetration pressure of the oil, so that when the oily wastewater contacts the mesh membrane, the water can pass more smoothly and has a higher separation flux, while the oil is better retained.

[0053] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, the second photoinitiator is selected from at least one of 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone (which can be a commercially available initiator 2959), 1,1'-[methylenebis(4,1-phenylene)]bis(2-hydroxy-2-methyl-1-propanone) (which can be a commercially available initiator 127), 1-hydroxycyclohexylphenyl ketone (which can be a commercially available initiator 184), 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone (which can be a commercially available initiator 907) and ethyl 2,4,6-trimethylbenzoylphenylphosphonate (which can be a commercially available initiator TPO-L). More preferably, the first photoinitiator and the second photoinitiator are the same initiator.

[0054] According to the present invention, preferably, the modification conditions include: time of 4-8 hours, temperature of 20-55° C., and wavelength of the second ultraviolet light of 300-400 nm. More preferably, the first ultraviolet light and the second ultraviolet light have the same wavelength.

[0055] According to the present invention, preferably, before the web forming process, the method further comprises: washing and drying the modified polypropylene fiber in sequence. The washing method may be to place the modified polypropylene fiber in an acetone solution and start ultrasound, the ultrasound time may be 12-24 hours, and then rinse with deionized water for more than 12 hours. The drying method may be drying at 75-85°C.

[0056] According to the present invention, preferably, in step (3), the web forming method comprises: sequentially performing carding, needling and heat sealing reinforcement.

[0057] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared modified mesh and further make the modified mesh effective for a long time, preferably, the mesh forming treatment conditions make the mesh weight 100-700g / m 2 , thickness is 20-70mm, porosity is 50-90%; more preferably, the netting treatment conditions make the net weight 200-500g / m 2 , thickness is 30-60mm, porosity is 60-85%. The inventors of the present invention have found in their research that when the above range, especially the range of the mesh porosity, is met, it can maintain a high oil removal rate and a large flux when used to treat oily wastewater, meeting the requirements of large-scale industrial applications.

[0058] In a second aspect, the present invention provides a modified omentum prepared by the method described above.

[0059] According to the present invention, preferably, the modified mesh is a three-dimensional porous mesh.

[0060] According to the present invention, preferably, the modified web has a gram weight of 100-700 g / m 2 (For example, it can be 100g / m 2 , 200g / m 2 , 300g / m 2 , 400g / m 2 , 500g / m 2 , 600g / m 2 , 700g / m 2 and the values ​​within the range formed by any two of the above values), the thickness is 20-70 mm (for example, it can be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm and the values ​​within the range formed by any two of the above values), and the porosity is 50-90 volume % (for example, it can be 50%, 60%, 70%, 80%, 90%); more preferably, the gram weight of the modified mesh is 200-500 g / m 2 , thickness is 30-60 mm, and porosity is 60-85% by volume.

[0061] According to the present invention, preferably, in the modified omentum, the content ratio of the structural unit derived from polypropylene to the structural unit derived from the modified functional monomer is 100:10-60 by weight.

[0062] According to the present invention, in order to further ensure long-term effectiveness, preferably, the modified omentum further contains an antioxidant.

[0063] According to the present invention, preferably, the antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (which may be commercially available antioxidant 1010), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (which may be commercially available antioxidant 1076) and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (which may be commercially available antioxidant 1790).

[0064] According to the present invention, preferably, in the modified omentum, the content ratio of the structural unit derived from polypropylene to the antioxidant is 9-99:1 by weight.

[0065] In a third aspect, the present invention provides the use of the modified mesh membrane as described above in treating oily wastewater.

[0066] In a fourth aspect, the present invention provides a treatment device for oily wastewater, which comprises, in order according to the direction of the material: a liquid storage tank and an oil-water separator;

[0067] Wherein, the liquid storage tank is used to store oily wastewater; the oil-water separator is filled with the modified mesh membrane as described above, which is used to separate oil from water;

[0068] The oil-water separator is also connected to a water production tank and an oil collection tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collection tank is used to receive the oil phase from the oil-water separator.

[0069] According to the present invention, preferably, the oily wastewater treatment device further comprises a sewage tank located between the liquid storage tank and the oil-water separator, and the sewage tank is used to receive the oily wastewater from the liquid storage tank and transport it to the oil-water separator. The sewage tank is provided with a sewage tank inlet and a sewage tank outlet; wherein the sewage tank inlet is connected to the liquid storage tank through a pipeline, and the sewage tank outlet is connected to the oil-water separator through a pipeline. According to the present invention, preferably, the oily wastewater treatment device further comprises a sewage pump located on the pipeline between the liquid storage tank and the sewage tank, which is used to pump the sewage in the liquid storage tank into the sewage tank.

[0070] According to the present invention, preferably, according to the flow of materials, the oily wastewater treatment device further comprises a flow regulating valve, a flow meter and a feed pump which are sequentially arranged on the pipeline between the wastewater tank and the oil-water separator.

[0071] According to the present invention, preferably, the oil-water separator is provided with a sewage inlet, a water phase outlet and an oil phase outlet. The sewage inlet is located at the upper part of the oil-water separator. The sewage inlet is used to introduce the oily sewage from the liquid storage tank into the oil-water separator, the water phase outlet is used to lead the water phase obtained after separation by the modified mesh membrane out of the oil-water separator and into the water production tank, and the oil phase outlet is used to lead the oil phase obtained after separation by the modified mesh membrane out of the oil-water separator and into the oil collection tank.

[0072] It can be understood that when the oily wastewater is separated through the oil-water separator, the modified mesh membrane filled therein has the function of hydrophilicity and oleophobicity. Under the selective interception effect, the water phase will pass through the modified mesh membrane and enter the lower part of the oil-water separator, and the oil phase will be intercepted and remain in the upper part of the oil-water separator. Preferably, the oil phase outlet is located at the top of the oil-water separator, and the water phase outlet is located at the lower part of the oil-water separator.

[0073] According to the present invention, preferably, the water production tank is communicated with the water phase outlet of the oil-water separator through a pipeline, and the oil collection tank is communicated with the oil phase outlet of the oil-water separator through a pipeline.

[0074] In a fifth aspect, the present invention provides a method for treating oily wastewater, characterized in that the method is carried out in the device as described above, and the method comprises: introducing the oily wastewater in the liquid storage tank into an oil-water separator to separate the oil and water.

[0075] According to the present invention, preferably, in the oil-water separator, the ratio of the filling volume of the modified mesh membrane to the volume of the oil-water separator is 1:2-4.

[0076] According to the present invention, preferably, in the oil-water separator, relative to the modified mesh membrane with a filling volume of 300L, the inflow rate of the oily wastewater is 0.1-0.5m 3 / h. The inventors of the present invention have found in their research that when the above range is met, the modified mesh membrane and the oily wastewater can be more fully contacted, and a higher oil removal rate can be obtained.

[0077] According to the present invention, preferably, the temperature of the oily wastewater is 40-60°C.

[0078] The loading volume may be the volume of the omentum loaded under conventional loading operations in the art, for example, the volume of the omentum loaded into the bed layer of the oil-water separator by layered compaction at 0.2 MPa.

[0079] According to a particularly preferred embodiment of the present invention, the preparation of the modified mesh membrane and the treatment of the wastewater are carried out according to the following method:

[0080] (1) Polypropylene with a melt index of 450-550 g / 10 min and antioxidant 1790 are added to a spinning kettle equipped with a stirring device and mixed, wherein the weight ratio of the antioxidant to the polypropylene is 20-30:1; melting is performed at 182-187° C.; stirring is then performed for 1.7-2.2 h under nitrogen flow; after stopping stirring, the spinning solution is allowed to stand for 0.5-0.6 h at 182-187° C. for degassing to obtain a spinning solution.

[0081] The spinning solution is filtered through a filter and then extruded at a temperature of 177-183°C; then spinning is performed with a spinneret aperture of 0.3-0.7m and a spinning temperature of 168-172°C; primary fibers are formed after being stretched by airflow at a temperature of 132-138°C, wherein the stretching spinning speed is 250-290m / min; and the primary fibers are cooled by air at 9-11°C to obtain polypropylene fibers.

[0082] For the polypropylene fiber, first immerse it in ethanol for washing for 9-11 hours, then wash it with deionized water for at least 3 times to remove impurities adsorbed on the surface of the polypropylene fiber; then place it in an oven and dry it at 70°C for more than 24 hours to remove moisture adsorbed on the surface.

[0083] The dried polypropylene fiber is immersed in a solution containing a first photoinitiator, wherein the first photoinitiator is initiator 907, the solvent of the solution is ethanol, the mass ratio of the polypropylene modified fiber to the first photoinitiator in the solution containing the first photoinitiator is 100:8-9, the fiber is immersed for 3.2-3.8 hours, the immersion temperature is 32-38° C., and the fiber is taken out after immersion and dried naturally; the dried polypropylene fiber is irradiated with a first ultraviolet light with a wavelength of 355-370 nm for 1.8-2.3 minutes in a N2 atmosphere at 32-38° C. to obtain a fiber filament whose surface is covered with a photoinitiator.

[0084] A solution containing a modified functional monomer and a second photoinitiator is prepared and the solution is ultrasonically degassed for 3 hours. In the solution, the modified functional monomer is methyl methacrylate, the second photoinitiator is initiator 907, the solvent is ethanol, the amount ratio of the modified functional monomer in the polypropylene fiber with the photoinitiator on the surface to the solution containing the modified functional monomer and the second photoinitiator is 100:35-42; the amount ratio of the second photoinitiator in the polypropylene fiber with the photoinitiator on the surface to the solution containing the modified functional monomer and the second photoinitiator is 100:2.5-3.5. The polypropylene fiber with the photoinitiator on the surface is immersed in the above solution and placed under the second ultraviolet light for modification. The modification time is 6.5-7.3 hours, the temperature is 32-38° C., and the wavelength of the second ultraviolet light is 355-370 nm. After modification, the fiber is taken out to obtain a modified polypropylene fiber.

[0085] The modified polypropylene fiber is first soaked in acetone and then ultrasonically cleaned for 12 hours, then rinsed with deionized water for 12 hours, and then placed in an oven at 80°C for drying. The modified polypropylene fiber after drying is taken out, and a modified web is obtained after being carded, needle-punched, and heat-sealed for reinforcement. The web-forming treatment conditions make the web weight 300-360g / m 2 , thickness is 43-48 mm, and porosity is 79-84% by volume.

[0086] (2) Layering and compacting the modified mesh membrane into the bed of the oil-water separator, wherein the ratio of the volume of the modified mesh membrane to the volume of the oil-water separator is 1:2.5-3.5;

[0087] (3) Pumping the oily wastewater in the liquid storage tank at a temperature of 40-60°C into the wastewater tank through a wastewater pump;

[0088] (4) Open the flow control valve and flow meter, and pump the liquid in the sewage tank into the oil-water separator through the feed pump. By adjusting the flow control valve, the feed rate is controlled to be 0.1-0.2m / s relative to the filling volume of 300L modified mesh membrane. 3 / h, the oily wastewater is treated, the separated oil phase enters the oil collecting tank through the oil phase outlet, and the water phase without the oil phase enters the water production tank through the water phase outlet.

[0089] The present invention will be described in detail below by way of examples. In the following examples and test examples:

[0090] Antioxidant 1010, the ingredient is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

[0091] Antioxidant 1076, the ingredient is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate;

[0092] Antioxidant 1790, the ingredient is 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione;

[0093] Initiator 2959, composed of 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone;

[0094] Initiator 127, composed of 1,1'-[methylenebis(4,1-phenylene)]bis(2-hydroxy-2-methyl-1-propanone);

[0095] Initiator 184, composed of 1-hydroxycyclohexyl phenyl ketone;

[0096] Initiator 907, composed of 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone;

[0097] Initiator TPO-L, composed of ethyl 2,4,6-trimethylbenzoylphenylphosphonate

[0098] The polypropylene melt index is measured by ASTM D1238-13 method at a temperature of 230° C. and a load weight of 2.16 kg.

[0099] The test method of the gram weight is: first use a gram weight tester to take a sample, then weigh it with a balance, and the number of grams obtained is divided by the area to get the gram weight (g / m 2 ).

[0100] The porosity was measured by mercury intrusion porosimetry using an Autopore IV-9500 fully automatic mercury intrusion porosimeter.

[0101] The tensile strength was tested using a 3342 universal material testing machine from INSTRON, USA. The total length of the specimen was 40 mm, the test temperature was 25 °C, and the loading speed was 40 mm / min.

[0102] The diameter of polypropylene fibers was measured using an XL-30 field emission scanning electron microscope.

[0103] The oil content in water is determined according to the national standard "GB / T 16488-1996 Water quality - Determination of petroleum, animal and vegetable oils".

[0104] The oil removal rate is calculated as follows:

[0105] Wherein, C0 represents the oil content of the oily wastewater in the wastewater tank, in mg / L;

[0106] C represents the oil content of the water phase in the water production tank, in mg / L.

[0107] Furthermore, unless otherwise specified, the materials described are all commercially available.

[0108] like Figure 1 As shown, the treatment device for oily wastewater of the present invention includes a liquid storage tank 1, a sewage pump 2, a sewage tank 3, a flow regulating valve 4, a flow meter 5, a feed pump 6, an oil-water separator 7, a water production tank 8 and an oil collecting tank 9 in sequence according to the direction of the material. The liquid storage tank 1 is used to store oily wastewater, wherein the temperature of the wastewater is 40-60°C, and is connected to the sewage pump 2 through a pipeline; the sewage pump 2 is connected to the sewage tank inlet of the sewage tank 3 through a pipeline, and is used to pump the oily wastewater in the liquid storage tank 1 into the sewage tank 3. The sewage tank outlet of the sewage tank 3 is connected to the feed pump 6 through a pipeline, and a flow regulating valve 4 and a flow meter 5 are arranged on the pipeline in sequence. The feed pump is connected to the sewage inlet of the oil-water separator 7 through a pipeline, and is used to pump the sewage in the sewage tank 3 into the oil-water separator 7 for treatment. The oil-water separator 7 is filled with a modified mesh membrane to treat the oily wastewater, that is, to separate the oil phase and the water phase. The oil-water separator comprises an oil phase outlet and a water phase outlet. The oil phase outlet is connected to the oil collecting tank 9 through a pipeline, and the water phase outlet is connected to the water production tank 8 through a pipeline.

[0109] Examples 1-9 and Comparative Examples 1-2

[0110] (1) Polypropylene and an antioxidant are added to a spinning kettle equipped with a stirring device, mixed and melted, and then stirred for a period of time under nitrogen flow. After stopping the stirring, the mixture is allowed to stand for a period of time for degassing to obtain a spinning solution.

[0111] The spinning solution is filtered through a filter screen, input into a screw extruder through a pipeline and extruded, and then ejected through a spinneret of a spinning assembly by a metering pump. Primary fibers are formed after being stretched by air flow, and the primary fibers are cooled by cooling air to obtain polypropylene fibers of uniform thickness.

[0112] The polypropylene fiber is first immersed in ethanol for washing, and then washed with deionized water for at least 3 times to remove impurities adsorbed on the surface of the polypropylene fiber; then it is placed in an oven and dried at 70°C for more than 24 hours to remove moisture adsorbed on the surface; the dried polypropylene fiber is immersed in a solution containing a first photoinitiator, and then taken out and dried naturally after a period of time; the dried polypropylene fiber is exposed to a first ultraviolet light in a N2 atmosphere to obtain a fiber filament whose surface is covered with a photoinitiator.

[0113] A modified functional monomer aqueous solution is prepared, mixed with a solution containing a second photoinitiator, and subjected to ultrasonic degassing treatment to obtain a homogeneous solution system, i.e., a solution containing the modified functional monomer and the second photoinitiator; a polypropylene fiber with the surface covered with the photoinitiator is immersed in the above solution, placed under a second ultraviolet light for a period of time, and then taken out to obtain a modified polypropylene fiber.

[0114] (3) The modified polypropylene fiber is first soaked in acetone and then ultrasonically cleaned for 12 hours, then rinsed with deionized water for 12 hours, and then dried in an oven at 80°C. The dried modified polypropylene fiber is taken and combed into a web, needle-punched, and heat-sealed to obtain a modified web film.

[0115] The condition parameters of each step and the material parameters of Example 1-9 and Comparative Example 1-2, as well as the gram weight, thickness and porosity of the mesh are shown in Table 1-5.

[0116] Table 1

[0117]

[0118] Table 2

[0119]

[0120]

[0121] Table 3

[0122]

[0123] Table 4

[0124]

[0125]

[0126] Table 5

[0127]

[0128]

[0129] Among them, Comparative Example 1 is carried out according to the method of Example 5, except that no grafting modification is performed; Comparative Example 2 is carried out according to the method of Example 5, except that the polypropylene fiber is not subjected to a web forming treatment; m (polypropylene resin: antioxidant) refers to the amount of the polypropylene and the antioxidant by weight.

[0130] Test Case

[0131] The modified omentum prepared in Example 1-9 and Comparative Example 1-2 was taken and its tensile strength was measured respectively. The results are shown in Table 6.

[0132] Take oily wastewater from a refinery, the pH value of the wastewater is 7, and the oil content is 11942 mg / L.

[0133] Take the modified omentum prepared in Examples 1-9 and Comparative Examples 1-2, which have been used for more than 6 months before this test, and Figure 1 The oily wastewater is treated in the oily wastewater treatment device shown.

[0134] The specific method is:

[0135] (1) The products prepared in Examples 1-9 and Comparative Examples 1-2 were respectively layered, compacted and loaded into the bed of an oil-water separator.

[0136] (2) Pump the oily wastewater in the liquid storage tank at a temperature of 40-60°C into the wastewater tank through a wastewater pump;

[0137] (3) Open the flow control valve and flow meter, and pump the liquid in the sewage tank into the oil-water separator through the feed pump. By adjusting the flow control valve, the flow rate of the oily sewage is controlled to be 0.1-0.5m / s relative to the filling volume of the 300L modified mesh membrane. 3 / h.

[0138] The specific operating conditions are shown in Table 6.

[0139] After the operation is stable, water in the water production tank is taken to measure the oil content and the oil removal rate is calculated. The results are shown in Table 6.

[0140] The packing ratio is the ratio of the packing volume of the modified mesh membrane to the volume of the oil-water separator.

[0141] Table 6

[0142]

[0143] From the data in Table 6, it can be seen that the modified omentum prepared by the technical solution of the present invention can still achieve a high oil removal rate when used for oil-water separation after 6 months of operation. It can be seen that the omentum prepared by the technical solution of the present invention can ensure long-term effectiveness. Compared with the product of the unmodified comparative example 1, the tensile strength of the modified omentum prepared by Examples 1-9 did not change significantly. The above results show that the modified omentum prepared by the method of the present invention can achieve a high oil removal rate without affecting the performance of the main material. Comparative Examples 1-2 did not adopt the technical solution of the present invention and the effect was poor.

[0144] In addition, the method of the present invention has a simple preparation process, mild conditions, easy operation, good repeatability, low preparation cost and energy consumption, and when the modified mesh prepared by the method of the present invention and the device provided by the present invention are used for oil removal, the treatment process is safe and explosion-proof, the operating cost is low, and no waste residue is generated.

[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a modified mesh membrane having an oil-water separation function, characterized in that: The method includes: (1) melting polypropylene and an antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers; (2) using a modified functional monomer solution to graft-modify the polypropylene fiber under the action of ultraviolet light to obtain a modified polypropylene fiber; (3) forming a web of modified polypropylene fibers to obtain a three-dimensional porous modified web membrane; Wherein, in step (1), according to the ASTM D1238-13 method, the melt index of the polypropylene at a temperature of 230° C. and a load weight of 2.16 kg is 500-1000 g / 10 min; Wherein, in step (2), the grafting modification method comprises: immersing the polypropylene fiber in a solution containing a first photoinitiator, subjecting the immersed polypropylene fiber to a first ultraviolet light treatment to obtain a polypropylene fiber whose surface is covered with the photoinitiator; immersing the polypropylene fiber whose surface is covered with the photoinitiator in a solution containing a modified functional monomer and a second photoinitiator, and modifying the fiber under the action of a second ultraviolet light to obtain a modified polypropylene fiber; Wherein, the usage ratio of the polypropylene to the antioxidant is 9-99:1 by weight; Wherein, the mass ratio of the polypropylene fiber to the first photoinitiator in the solution containing the first photoinitiator is 100:5-10; Wherein, the mass ratio of the polypropylene fiber with the surface covered with the photoinitiator to the modified functional monomer and the modified functional monomer in the solution containing the second photoinitiator is 100:10-60; Wherein, the mass ratio of the polypropylene fiber with the surface covered with the photoinitiator to the second photoinitiator in the solution containing the modified functional monomer and the second photoinitiator is 100:0.5-5; The modified functional monomer is selected from at least one of acrylic acid, methacrylic acid, methyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, and N,N-dimethylacrylamide.

2. The method according to claim 1, wherein: The antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

3. The method according to claim 1, wherein: The melting temperature is 175-210°C.

4. The method according to claim 1, wherein: The method further comprises: stirring and degassing after melting.

5. The method according to claim 1, wherein: The spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution.

6. The method according to claim 1, wherein: The spinning conditions are such that the diameter of the polypropylene fiber is 10-40 μm.

7. The method according to claim 1, wherein: The soaking conditions include: time of 1-6 hours and temperature of 20-55°C.

8. The method according to claim 1, wherein: The conditions of the first ultraviolet light treatment include: in an inert gas atmosphere, the time is 0.5-3 minutes, the temperature is 20-55° C., and the wavelength of the first ultraviolet light is 300-400 nm.

9. The method according to claim 1, wherein: The first photoinitiator is selected from at least one of 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 1,1'-[methylenebis(4,1-phenylene)]bis(2-hydroxy-2-methyl-1-propanone), 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

10. The method according to claim 1, wherein: The second photoinitiator is selected from at least one of 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 1,1'-[methylenebis(4,1-phenylene)]bis(2-hydroxy-2-methyl-1-propanone), 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholine-1-propanone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

11. The method according to claim 1, wherein: The modification conditions include: time of 4-8 hours, temperature of 20-55° C., and wavelength of the second ultraviolet light of 300-400 nm.

12. The method according to claim 1, wherein: In step (3), the web forming method comprises: combing, needling and heat-sealing reinforcement in sequence.

13. The method according to claim 1, wherein: The conditions of the web forming process are such that the weight of the web is 100-700 g / m 2 , thickness is 20-70mm, and porosity is 50-90%.

14. The method according to claim 13, wherein: The conditions of the web forming process are such that the weight of the web is 200-500 g / m 2 , thickness is 30-60mm, porosity is 60-85%.

15. The modified omentum prepared by the method according to any one of claims 1 to 14.

16. The modified omentum according to claim 15, wherein: The modified mesh is a three-dimensional porous mesh.

17. The modified omentum according to claim 15, wherein: The modified web has a gram weight of 100-700 g / m 2 , thickness is 20-70 mm, and porosity is 50-90% by volume.

18. The modified omentum according to claim 17, wherein: The modified web has a gram weight of 200-500 g / m 2 , thickness is 30-60 mm, and porosity is 60-85% by volume.

19. The modified omentum according to claim 15, wherein: In the modified mesh, the content ratio of the structural unit derived from polypropylene to the structural unit derived from the modified functional monomer is 100:10-60 by weight.

20. The modified omentum according to claim 15, wherein: The modified omentum also contains an antioxidant.

21. The modified omentum according to claim 20, wherein: The antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

22. The modified omentum according to claim 20, wherein: In the modified mesh, the content ratio of the structural unit derived from polypropylene to the antioxidant is 9-99:1 by weight.

23. Use of the modified mesh membrane according to any one of claims 15 to 22 in treating oily wastewater.

24. A treatment device for oily wastewater, which comprises, in order according to the direction of the material: Liquid storage tank and oil-water separator; Wherein, the liquid storage tank is used to store oily wastewater; the oil-water separator is filled with the modified mesh membrane according to any one of claims 15 to 22 for oil-water separation; The oil-water separator is also connected to a water production tank and an oil collection tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collection tank is used to receive the oil phase from the oil-water separator.

25. A method for treating oily wastewater, characterized in that: The method is carried out in the device described in claim 24, and the method comprises: introducing the oily wastewater in the liquid storage tank into the oil-water separator to separate the oil and water.

26. The method according to claim 25, wherein: In the oil-water separator, the ratio of the filling volume of the modified mesh membrane to the volume of the oil-water separator is 1:2-4.

27. The method according to claim 25, wherein: In the oil-water separator, relative to the modified mesh membrane with a filling volume of 300L, the inflow rate of the oily wastewater is 0.1-0.5m 3 / h.

28. The method according to claim 25, wherein: The temperature of the oily wastewater is 40-60°C.

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