Cross-linked modified omentum, preparation method, application, and oily wastewater treatment device and method

Abstract

The present invention relates to the field of oil-water separation, and specifically to a cross-linked modified mesh, a preparation method, and its application, as well as an apparatus 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) modifying the polypropylene fibers using a hydrophilic modification compound under the action of a cross-linking agent to obtain modified polypropylene fibers; (3) subjecting the modified polypropylene fibers to a web-forming treatment to obtain a cross-linked modified mesh having a three-dimensional network. The method of the present invention has a simple preparation process, and the resulting mesh has a high oil-water separation efficiency, a long-lasting modification effect that does not affect the mechanical properties of the base material, a low operating cost, no secondary pollution, and can ensure that the effluent indicators are stable and meet standards even in long-term operation.

Description

Technical Field

[0001] The present invention relates to the field of oil-water separation, and in particular to a cross-linked modified omentum, a preparation method thereof, and an application thereof, as well as a treatment device and a treatment method for oily wastewater. Background Art

[0002] Oily wastewater causes serious pollution and damage to the hydrosphere, biosphere, and atmosphere, endangering human health and the living environment. The treatment of oily wastewater is an urgent problem that needs to be solved today. The treatment of oily wastewater based on membrane separation technology 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 when separating oil-water emulsions, traditional two-dimensional porous polymer separation membranes have a trade-off effect in flux and selectivity, making it difficult to achieve both high permeability and high selectivity. The flux decays quickly, the separation efficiency is low, external driving pressure is required, fouling is easy to occur, the types of oily wastewater that can be treated are limited, and it is impossible to separate water-in-oil and oil-in-water emulsions at the same time.

[0003] The essence of oil-water separation is an interface problem. By designing the special wettability of the material surface and taking advantage of the difference in the residence time of the oil-water two-phase penetration behavior when the oil-water mixture contacts the surface of a composite material with special wettability, oil-water separation can be achieved without other auxiliary measures such as chemical agents. In other words, the selective interception technology can be used to treat oily wastewater, which is currently the cutting-edge technology for oil-water separation.

[0004] Blending membrane materials with hydrophilic polymers can impart lasting hydrophilicity to polypropylene fibers. However, the disadvantage is that the blending components need to be able to co-crystallize with polypropylene and not be destroyed at high temperatures. Otherwise, the degree of crystallization of polypropylene will be affected, reducing the mechanical properties and modification effect of the polypropylene fiber, and the preparation parameters need to be readjusted. Using hydrophilic substances such as ethanol, certain surfactants, or amphiphilic solvents to soak and coat polypropylene fibers is a simple modification method, but the substances are easily washed away and lost, rendering the oil-water wetting balance performance control ineffective. Restoring performance requires further modification after the failure. Furthermore, current oil-water separation materials still suffer from low oil-water separation efficiency.

[0005] Therefore, it is necessary to develop a material with high oil-water separation efficiency. The preparation process of this material is simple, the modification effect is long-lasting and does not affect the mechanical properties of polypropylene itself. In addition, the operating cost of this material is low, it will not cause secondary pollution, and long-term operation can ensure that the water effluent indicators are stable and meet the standards. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a cross-linked modified omentum and a preparation method and application thereof, as well as a treatment device and a treatment method for oily wastewater. The omentum preparation process is simple, has a high oil-water separation efficiency, a long-lasting modification effect without affecting the mechanical properties of the main material, has a low operating cost, will not cause secondary pollution, and can ensure that the effluent indicators are stable and meet the standards during long-term operation.

[0007] In order to achieve the above object, the present invention provides a method for preparing a cross-linked modified omentum, which comprises:

[0008] (1) melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers;

[0009] (2) modifying the polypropylene fiber using a hydrophilic modification compound under the action of a crosslinking agent to obtain a modified polypropylene fiber;

[0010] (3) The modified polypropylene fiber is subjected to a mesh-forming process to obtain a cross-linked modified mesh film having a three-dimensional mesh shape.

[0011] The second aspect of the present invention provides a cross-linked modified omentum prepared by the method described above.

[0012] The third aspect of the present invention provides the use of the cross-linked modified omentum as described above in treating oily wastewater.

[0013] A fourth aspect of the present invention provides a device for treating oily wastewater, which comprises, in order according to the direction of the material, a liquid storage tank and an oil-water separator;

[0014] Wherein, the liquid storage tank is used to store oily wastewater; the oil-water separator is filled with the cross-linked modified mesh membrane as described above for oil-water separation;

[0015] The oil-water separator is further connected to a water production tank and an oil collecting tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collecting tank is used to receive the oil phase from the oil-water separator.

[0016] A fifth aspect of the present invention provides a method for treating oily wastewater, which is carried out in the apparatus described above. The method comprises: introducing the oily wastewater in the liquid storage tank into an oil-water separator for oil-water separation.

[0017] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0018] 1. The cross-linked modified omentum prepared by the method provided by the present invention has the function of intercepting oil and conducting water, and has a high oil-water separation efficiency.

[0019] 2. The preparation method provided by the present invention is simple in preparation, does not require overly complex equipment, and is suitable for industrial-scale production. Furthermore, it can achieve a strong bond between the modifier and the base material without significantly affecting the mechanical properties of the base material, resulting in a long-lasting modification effect and ensuring stable and satisfactory water quality even in long-term operation.

[0020] 3. The oily wastewater treatment device provided by the present invention has a compact structure and a small size. When it is used to treat oily wastewater, the treatment process is safe and explosion-proof, with low operating costs and high efficiency, and does not produce any waste residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The invention provides a device for treating oily wastewater.

[0022] Description of Reference Numerals

[0023] 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-Production water tank; 9-Oil collecting tank. DETAILED DESCRIPTION

[0024] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0025] In a first aspect, the present invention provides a method for preparing a cross-linked modified omentum, 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) modifying the polypropylene fiber using a hydrophilic modification compound under the action of a crosslinking agent to obtain a modified polypropylene fiber;

[0028] (3) The modified polypropylene fiber is subjected to a mesh-forming process to obtain a cross-linked modified mesh film having a three-dimensional mesh shape.

[0029] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared omentum and further ensure the long-term effectiveness of the omentum, preferably, in step (1), the polypropylene has a melt index of 100-1000 g / 10 min at a temperature of 230° C. and a load of 2.16 kg according to the ASTM D1238-13 method. The inventors of the present invention have found that polypropylene in this melt index range has better fluidity and processability, and the mechanical properties of the prepared omentum are better, which is more conducive to improving the oil removal rate of the omentum.

[0030] According to the present invention, in order to further make the omentum effective for a long time, preferably, the antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl) phosphite (such as the commercially available antioxidant 168), a mixture of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol and tris(2,4-di-tert-butylphenyl) phosphite (such as the commercially available antioxidant B215) and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol (such as the commercially available antioxidant B225).

[0031] According to the present invention, preferably, the ratio of the polypropylene to the antioxidant is 9-99:1 by weight.

[0032] According to the present invention, preferably, the melting temperature is 175-210°C (for example, 175°C, 180°C, 190°C, 200°C, 210°C).

[0033] According to the present invention, in order to make the spinning solution more uniform and thus further improve the oil-water separation efficiency of the prepared omentum, preferably, the method further comprises: stirring and degassing after melting.

[0034] According to the present invention, the specific operation of the stirring is not particularly limited, as long as it can make the melted material more uniform. Preferably, the stirring method includes: stirring for 1-4 hours under nitrogen flow.

[0035] According to the present invention, preferably, the degassing conditions include: a temperature of 175-210° C., and standing for 0.5-2 hours for degassing.

[0036] 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.

[0037] According to the present invention, preferably, the spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution.

[0038] According to the present invention, in order to further improve the oil removal rate of the omentum, the spinning conditions are such that the diameter of the polypropylene fiber is 10-40 μm (for example, 10 μm, 20 μm, 30 μm, 40 μm).

[0039] It is understood that the specific operating conditions of the extrusion, spinning, stretching and cooling are not particularly limited, as long as the diameter of the obtained polypropylene fiber is 10-40 μm. However, according to the present invention, preferably, the extrusion conditions include: a temperature of 160-200°C (for example, 160°C, 170°C, 180°C, 190°C, 200°C). The extrusion device is not particularly limited, and is preferably fed into a screw extruder through a pipeline. For example, the spinning solution is fed into a screw extruder through a pipeline and extruded, wherein the pipeline temperature, i.e., the extrusion temperature, is 160-200°C.

[0040] According to the present invention, preferably, the spinning conditions include: a spinneret aperture of 0.05-2 mm, and a temperature of 145-180°C.

[0041] According to the present invention, preferably, the stretching conditions include: using airflow stretching, the airflow temperature is 120-150°C, and the stretching spinning speed is 100-400 m / min. It can be understood that the spinning speed refers to the speed at which the fiber is formed during the airflow stretching process.

[0042] According to the present invention, preferably, the cooling condition includes: using air cooling, and the air temperature is 5-20°C.

[0043] According to the present invention, preferably, before modification, the method further comprises: washing and drying the polypropylene fibers in sequence. The washing is to remove impurities adhering to the polypropylene fibers, and the drying is to remove liquid adhering to the washed polypropylene fibers. The specific washing and drying methods are not particularly limited. Preferably, the washing is performed by first soaking the fibers in ethanol for 4-12 hours, followed by at least three rinses in deionized water. Preferably, the drying is performed at 65-75°C for at least 24 hours.

[0044] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared omentum and further make the omentum effective for a long time, preferably, in step (2), the modification method includes: immersing the polypropylene fiber in a first crosslinking agent solution for pretreatment to obtain a polypropylene fiber with a surface covered with a crosslinking agent; immersing the polypropylene fiber with a surface covered with a crosslinking agent in a hydrophilic modified compound solution for deposition to obtain deposited polypropylene fiber; immersing the deposited polypropylene fiber in a second crosslinking agent solution and performing a crosslinking reaction under the action of a catalyst to obtain a modified polypropylene fiber.

[0045] The inventors of the present invention have found in their research that when the polypropylene fiber is immersed in a first crosslinking agent solution for pretreatment, the surface energy of the polypropylene fiber can be reduced, so that the first crosslinking agent covers the surface of the polypropylene fiber as much as possible; when the polypropylene fiber with the surface covered by the crosslinking agent is immersed in a hydrophilic modification compound solution, the hydrophilic modification compound can be spread more evenly on the surface of the polypropylene fiber, and the first crosslinking agent that has already covered the surface of the polypropylene fiber can now simultaneously have an affinity for the hydrophilic modification compound and the polypropylene fiber. This amphiphilic effect can make the combination of the hydrophilic modification compound and the polypropylene fiber more firmly. In this way, the deposition amount of the hydrophilic modification compound can also be flexibly adjusted. The deposited polypropylene fiber is then immersed in a second crosslinking agent solution, which can be crosslinked in situ, further fixing the modification compound, thereby making the modification effect more durable. Through this deposition and crosslinking method, the surface of the polypropylene fiber can be given new oil-water wetting properties, and the modification of the polypropylene will be more limited to the surface of the polypropylene fiber, with less impact on the mechanical properties of the polypropylene fiber itself.

[0046] According to the present invention, preferably, the amount of the first cross-linking agent in the first cross-linking agent solution is 100-500 g relative to 1 kg of polypropylene fiber.

[0047] According to the present invention, in order to cover the surface of the polypropylene fiber with a larger amount of the first cross-linking agent so that it can be affinity with more hydrophilic modified compounds and further improve the oil-water separation efficiency of the prepared omentum, preferably, the pretreatment conditions include: time of 24-72h and temperature of 25-75°C.

[0048] According to the present invention, preferably, before deposition, the method further comprises: drying the polypropylene fiber with the surface covered with the cross-linking agent to remove the solvent attached to the surface.

[0049] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared omentum and further make the omentum effective for a long time, preferably, the molecular weight of the hydrophilic modified compound is 61-20000 g / mol.

[0050] According to the present invention, in order to deposit more hydrophilic modification compounds and further improve the oil-water separation efficiency of the prepared omentum, preferably, the mass ratio of the polypropylene fibers to the hydrophilic modification compound in the hydrophilic modification compound solution is 100:5-30. The concentration and amount of the hydrophilic modification compound solution are not particularly limited, as long as they meet the above ranges.

[0051] According to the present invention, in order to further improve the oil-water separation efficiency of the prepared omentum and further make the omentum effective for a long time, preferably, the hydrophilic modified compound is selected from at least one of polyethyleneimine, polylysine, polyarginine, ethanolamine, histidine, chitosan quaternary ammonium salt, and carboxymethyl chitosan. The inventors of the present invention have found in research that the use of such hydrophilic modified compounds can better cooperate with polypropylene fibers to play a role, so that the prepared omentum has better oil interception and water conduction functions and higher oil-water separation efficiency.

[0052] According to the present invention, in order to deposit more hydrophilic modified compounds and further improve the oil-water separation efficiency of the prepared membrane, preferably, the deposition conditions include: time of 12-48 hours and temperature of 25-75°C.

[0053] According to the present invention, preferably, after deposition, the deposited polypropylene fibers are dried to remove the solvent attached to the surface.

[0054] Relative to 1 kg of polypropylene fiber, the amount of the second cross-linking agent in the second cross-linking agent solution is 50-200 g.

[0055] According to the present invention, in order to further enhance the crosslinking effect and thereby improve the oil-water separation efficiency of the prepared omentum, preferably, the first crosslinking agent and the second crosslinking agent are each independently selected from at least one of glutaraldehyde, formaldehyde, succinyl dialdehyde, glyoxal, ethylene glycol bisglycidyl ether, and epichlorohydrin. More preferably, the first crosslinking agent and the second crosslinking agent are the same.

[0056] According to the present invention, in order to further enhance the crosslinking effect and thus improve the oil-water separation efficiency of the prepared omentum, preferably, the catalyst is selected from any one of sulfuric acid, hydrochloric acid, or nitric acid. For example, a sulfuric acid solution with a concentration of 45-50% by mass, a hydrochloric acid solution with a concentration of 32-38% by mass, or a nitric acid solution with a concentration of 64-70% by mass can be selected.

[0057] According to the present invention, preferably, the amount of the catalyst used is 5-50 g relative to 1 kg of polypropylene fiber. It is understood that if the catalyst used is a sulfuric acid solution with a concentration of 48% by mass, the amount of the catalyst used refers to the amount of sulfuric acid in the sulfuric acid solution, not the amount of the sulfuric acid solution used.

[0058] According to the present invention, preferably, the cross-linking reaction conditions include: a time of 1-6 hours and a temperature of 25-75°C. The inventors of the present invention have found that when the above conditions are adopted, better cross-linking effects can be achieved while reducing time and energy costs. It is understood that during the cross-linking reaction, the materials can also be stirred to make the materials more uniform, the reaction more complete, and achieve better cross-linking effects.

[0059] According to the present invention, preferably, before the web forming process, the method further comprises: sequentially subjecting the polypropylene fibers that have undergone the cross-linking reaction to coagulation treatment, washing, and drying.

[0060] Preferably, the coagulation treatment method comprises immersing the cross-linked polypropylene fibers in an alkaline aqueous solution. More preferably, the alkaline aqueous solution is an aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide, or ammonia, with a mass concentration of 1-10% by mass; and the coagulation treatment lasts for 1-12 hours. The inventors of the present invention have discovered that the coagulation treatment described above can enhance the mechanical strength of the polypropylene fibers without affecting the modification effect, further ensuring that the prepared mesh can maintain its effectiveness and long-term operation.

[0061] The washing and drying methods are not particularly limited, as long as they can remove impurities attached to the coagulated polypropylene fibers and the liquid attached after washing. Preferably, the washing method is to rinse with deionized water for more than 12 hours; and the drying method is to dry at 75-85°C.

[0062] According to the present invention, preferably, the web forming method comprises: carding, needling, and heat-sealing in sequence. It is understood that the carding is to use a carding machine to comb the fibers so that they are arranged neatly into a shape, the needling is to use a needle loom to needle the formed fibers so that the fibers are intertwined and connected to form a web, and the heat-sealing is to use a hot melt adhesive to further fix the fibers into a web film.

[0063] According to the present invention, preferably, the conditions of the web forming process are such that the weight of the cross-linked modified web is 150-650 g / m 2 (For example, it can be 150g / m 2 , 200g / m 2 , 300g / m 2 , 400g / m 2 , 500g / m 2 , 600g / m 2 , 650g / m 2) thickness is 25-80 mm (for example, 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm); more preferably, the conditions of the web forming process make the weight of the cross-linked modified web be 200-500 g / m 2 , with a thickness of 30-60 mm. Within a certain numerical range, increasing the grammage and thickness of the modified omentum increases the critical penetration pressure, improves the oil retention and repellency, and increases the oil removal rate, but decreases the flux. However, the inventors of the present invention have discovered that when the grammage and thickness of the omentum fall within the above ranges, it is possible to maintain a high oil removal rate and a large flux when treating oily wastewater, meeting the requirements of large-scale industrial applications.

[0064] In a second aspect, the present invention provides a cross-linked modified omentum prepared by the method described above.

[0065] According to the present invention, preferably, the omentum has a three-dimensional network structure.

[0066] According to the present invention, preferably, in the omentum, the content ratio of the structural unit derived from polypropylene to the structural unit derived from the hydrophilic modified compound is 100:5-30.

[0067] According to the present invention, preferably, the weight of the mesh is 150-650g / m 2 , thickness is 25-80mm; more preferably, the weight of the omentum is 200-500g / m 2 , thickness is 30-60mm.

[0068] According to the present invention, preferably, the omentum further contains an antioxidant.

[0069] According to the present invention, preferably, in the omentum, the content ratio of the polypropylene to the antioxidant is 9-99:1 by weight.

[0070] In a third aspect, the present invention provides the use of the cross-linked modified omentum as described above in treating oily wastewater.

[0071] 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;

[0072] Wherein, the liquid storage tank is used to store oily wastewater; the oil-water separator is filled with the cross-linked modified mesh membrane as described above for oil-water separation;

[0073] The oil-water separator is further connected to a water production tank and an oil collecting tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collecting tank is used to receive the oil phase from the oil-water separator.

[0074] According to the present invention, the oily wastewater treatment device preferably further includes a sewage tank located between the liquid storage tank and the oil-water separator, the sewage tank being 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, a sewage tank outlet, and a gas inlet; the sewage tank inlet is connected to the liquid storage tank via a pipeline, the sewage tank outlet is connected to the oil-water separator via a pipeline, and the gas inlet is used to input gas into the sewage tank to push the oily wastewater into the oil-water separator.

[0075] According to the present invention, preferably, the oily wastewater treatment device further comprises a sewage pump located on a pipeline between the liquid storage tank and the sewage tank, for pumping the sewage in the liquid storage tank into the sewage tank.

[0076] According to the present invention, preferably, according to the flow of materials, the oily wastewater treatment device further includes a flow regulating valve, a flow meter and a feed pump sequentially arranged on the pipeline between the wastewater tank and the oil-water separator.

[0077] According to the present invention, the oil-water separator is preferably provided with a sewage inlet, a water phase outlet, and an oil phase outlet. The sewage inlet is located at the upper portion of the oil-water separator. The sewage inlet is used to introduce oily sewage from the liquid storage tank into the oil-water separator, the water phase outlet is used to draw the water phase separated by the cross-linked modified membrane out of the oil-water separator and into the water production tank, and the oil phase outlet is used to draw the oil phase separated by the cross-linked modified membrane out of the oil-water separator and into the oil collection tank.

[0078] It is understood that when oily wastewater is separated through the oil-water separator, the cross-linked modified membrane loaded therein has hydrophilic and oleophobic properties. Under the combined effects of selective retention and coalescence separation, the aqueous phase will pass through the cross-linked modified membrane and enter the lower portion of the oil-water separator, while the oil phase will be retained and remain in the upper portion 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 portion of the oil-water separator.

[0079] 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 collecting tank is communicated with the oil phase outlet of the oil-water separator through a pipeline.

[0080] Among them, when the above-mentioned device is used to treat oily wastewater, the treatment process is safe and explosion-proof, and no waste residue is generated after the treatment. The efficiency is high and the operating cost is low.

[0081] In a fifth aspect, the present invention provides a method for treating oily wastewater, which is carried out in the apparatus described above. The method comprises: introducing the oily wastewater in the liquid storage tank into an oil-water separator for oil-water separation.

[0082] According to the present invention, in order to further improve the oil-water separation efficiency, preferably, the ratio of the loading volume of the cross-linked modified omentum to the volume of the oil-water separator is 1:2-4 (e.g., 1:2, 1:3, 1:4). The loading volume can be the volume of the omentum loaded under conventional loading operations in the art. For example, it can be the volume of the omentum loaded into the bed of the oil-water separator under layered compaction at 0.2 MPa.

[0083] According to the present invention, preferably, in the oil-water separator, relative to the cross-linked modified mesh membrane with a filling volume of 300L, the oily wastewater feed rate is 0.1-0.5m 3 The inventors of the present invention have found in their research that when the above range is met, the cross-linked modified omentum and the oily wastewater can be more fully contacted, thereby achieving a higher oil removal rate.

[0084] According to the present invention, preferably, the temperature of the oily wastewater is 40-60°C.

[0085] According to a particularly preferred embodiment of the present invention, the preparation of the cross-linked modified omentum and the treatment of the oily wastewater are carried out according to the following method:

[0086] (1) Preparing a spinning solution: polypropylene with a melt index of 550-650 g / 10 min and an antioxidant tris(2,4-di-tert-butylphenyl)phosphite, in a weight ratio of 17-21:1, are added to a spinning kettle equipped with a stirring device for mixing, heated to 187-193° C. for melting, and stirred under nitrogen for 3.3-3.7 hours. After stopping stirring, the mixture is allowed to stand at 187-193° C. for degassing for 0.8-1.2 hours to obtain a spinning solution. The spinning solution is then filtered through a filter.

[0087] Spinning: The filtered spinning solution is fed into a screw extruder through a pipeline for extrusion at a temperature of 183-187°C. The solution is then pumped through a metering pump through the spinneret of a spinning assembly for spinning at a temperature of 147-153°C and an aperture of 0.8-1.2mm. The solution is then stretched by a high-temperature airflow at a temperature of 143-147°C and a spinning speed of 280-310m / min to form nascent fibers. The nascent fibers are then cooled with air at a temperature of 13-15°C to obtain polypropylene fibers of uniform thickness.

[0088] The polypropylene fiber was first soaked and washed with ethanol for 5.5-6.5 hours, then washed with deionized water for at least 3 times to remove impurities adsorbed on the surface of the polypropylene fiber, and then placed in an oven at 70°C for more than 24 hours to remove moisture adsorbed on the surface.

[0089] Pretreatment: The polypropylene fibers are immersed in a glutaraldehyde solution (a first crosslinking agent solution) to obtain a surface-coated polypropylene fiber. The mass of the first crosslinking agent in the first crosslinking agent solution is 280-370 g per 1 kg of the polypropylene fiber. The pretreatment time is 46-49 hours, and the pretreatment temperature is 49-51 hours. After pretreatment, the surface-coated polypropylene fibers are air-dried to remove the solvent adhering to the surface.

[0090] Deposition: Immerse the polypropylene fiber, surface-coated with a crosslinker, in a solution of a hydrophilic modification compound at 49-51°C for 34-38 hours. The hydrophilic modification compound is carboxymethyl chitosan with a molecular weight of 8,000-12,000. The amount of the hydrophilic modification compound solution is such that, by weight, the ratio of structural units derived from polypropylene to structural units derived from the hydrophilic modification compound in the omentum is 8-11:1. After the hydrophilic modification compound is deposited on the surface of the polypropylene fiber, it is removed to obtain the deposited polypropylene fiber, which is then air-dried.

[0091] Cross-linking Reaction: The deposited polypropylene fibers were immersed in a glutaraldehyde solution (second cross-linking agent solution) and simultaneously added with 34-38% by mass hydrochloric acid (catalyst), with the catalyst amount being 26-34 g per kg of polypropylene fiber. The cross-linking reaction was conducted at 53-58°C with stirring for 4.5-5.5 hours. The mass of the second cross-linking agent in the second cross-linking agent solution was 140-180 g per kg of polypropylene fiber. The cross-linked polypropylene fibers were then immersed in a 7.5-8.5% by mass calcium hydroxide aqueous solution for coagulation for 5.5-6.5 hours. The fibers were then rinsed with deionized water for at least 12 hours and dried at 80°C to yield modified polypropylene fibers.

[0092] Web forming treatment: Take modified polypropylene fiber, card it into a web, needle punch it, and heat-seal it to obtain a three-dimensional cross-linked modified web.

[0093] (2) The mesh is compacted and loaded into the bed of the oil-water separator in layers, with the ratio of the mesh loading volume to the volume of the oil-water separator being 1:2.5-3.5;

[0094] (3) The oily wastewater in the storage tank with a temperature of 45-55°C is pumped into the wastewater tank through a wastewater pump;

[0095] (4) Open the flow regulating 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 regulating valve, the water flow rate is controlled to be 0.1-0.2m / s relative to the cross-linked modified membrane with a filling volume of 300L. 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.

[0096] The present invention will be described in detail below by way of examples. In the following examples, in the following examples and test examples:

[0097] Antioxidant 168, the ingredient is tris(2,4-di-tert-butylphenyl) phosphite;

[0098] Antioxidant B215, a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and tris(2,4-di-tert-butylphenyl) phosphite;

[0099] Antioxidant B225, composed of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0100] The polypropylene melt index is determined by ASTM D1238-13 method at a temperature of 230°C and a load weight of 2.16 kg.

[0101] The test method of the gram weight is as follows: first take a sample with a gram weight tester, then weigh it with a balance, and the number of grams obtained is divided by the area to obtain the gram weight (g / m 2 ).

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

[0103] 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.

[0104] The oil content in water is determined according to the national standard GB / T16488-1996 Water quality - Determination of petroleum, animal and vegetable oils.

[0105] The oil removal rate is calculated as follows:

[0106] Wherein, C0 represents the oil content of the oily wastewater in the wastewater tank, in mg / L;

[0107] C represents the oil content of the water phase in the water production tank, in mg / L.

[0108] Furthermore, unless otherwise specified, the materials described are all commercially available.

[0109] like Figure 1As shown, the oily wastewater treatment device of the present invention comprises, in order of material flow, 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 collection tank 9. Liquid storage tank 1 stores oily wastewater at a temperature of 40-60°C and is connected to sewage pump 2 via a pipeline. Sewage pump 2 is connected to the sewage tank inlet of sewage tank 3 via a pipeline and is used to pump the oily wastewater in liquid storage tank 1 into sewage tank 3. The sewage tank outlet of sewage tank 3 is connected to feed pump 6 via a pipeline, on which flow regulating valve 4 and flow meter 5 are sequentially installed. The feed pump is connected to the sewage inlet of oil-water separator 7 via a pipeline and is used to pump the wastewater in sewage tank 3 into oil-water separator 7 for treatment. Oil-water separator 7 is filled with a modified mesh membrane to treat the oily wastewater, that is, to separate the oil phase from the water phase. The oil-water separator includes 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.

[0110] Examples 1-9 and Comparative Examples 1-2

[0111] (1) Preparation of spinning solution: Polypropylene and antioxidant are added to a spinning kettle equipped with a stirring device and mixed. The mixture is heated to a certain temperature to melt the mixture and stirred for a period of time under nitrogen flow. After stopping the stirring, the mixture is allowed to stand and deaerate to obtain a spinning solution. The spinning solution is then filtered through a filter.

[0112] Spinning: The filtered spinning solution is fed into a screw extruder through a pipeline for extrusion; it is then spun through the spinneret of the spinning assembly via a metering pump; it is then stretched by high-temperature airflow to form nascent fibers; the nascent fibers are cooled by air to obtain polypropylene fibers of uniform thickness.

[0113] The polypropylene fiber was first soaked and washed with ethanol, and then washed with deionized water for at least 3 times to remove impurities adsorbed on the surface of the polypropylene fiber. It was then placed in an oven and dried at 70°C for more than 24 hours to remove moisture adsorbed on the surface.

[0114] Pretreatment: The polypropylene fiber is immersed in a first crosslinking agent solution for pretreatment to obtain a polypropylene fiber with a surface covered with the crosslinking agent. After pretreatment, the polypropylene fiber with a surface covered with the crosslinking agent is air-dried to remove the solvent attached to the surface.

[0115] Deposition: The polypropylene fiber with the surface covered with a cross-linking agent is immersed in a hydrophilic modified compound solution for deposition. The hydrophilic modified compound is deposited on the surface of the polypropylene fiber for a period of time and then taken out to obtain the deposited polypropylene fiber, which is then dried.

[0116] Cross-linking reaction: The deposited polypropylene fibers are immersed in a second cross-linking agent solution, a catalyst is added, and a cross-linking reaction is carried out under stirring. The cross-linked polypropylene fibers are then immersed in an alkaline aqueous solution for coagulation, then rinsed with deionized water for more than 12 hours and dried at 80°C to obtain modified polypropylene fibers.

[0117] (3) Netting treatment: Take modified polypropylene fibers, comb them into a net, needle punch them, and heat-seal and reinforce them to obtain a cross-linked modified net film with a three-dimensional network.

[0118] The condition parameters of each step and each material parameter of Examples 1-9 and Comparative Examples 1-2, as well as the gram weight and thickness of the web are shown in Table 1-5.

[0119] Table 1

[0120]

[0121]

[0122] Table 2

[0123]

[0124] Table 3

[0125]

[0126] Table 4

[0127]

[0128]

[0129] Table 5

[0130]

[0131]

[0132] Among them, Comparative Example 1 is carried out according to the method of Example 5, except that no 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 process; wherein, m (polypropylene resin: antioxidant) refers to the amount ratio of the polypropylene and the antioxidant by weight; m (polypropylene fiber: hydrophilic modified compound) refers to the mass ratio of the polypropylene fiber and the hydrophilic modified compound in the hydrophilic modified compound solution.

[0133] Test Example 1

[0134] Take the oily wastewater from a refinery, the pH of the wastewater is 8, and the oil content is 15134 mg / L.

[0135] 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.

[0136] The specific method is:

[0137] (1) The products prepared in Examples 1-9 and Comparative Examples 1-2 were compacted and loaded into the bed of an oil-water separator in layers.

[0138] (2) The oily wastewater in the storage tank with a temperature of 40-60°C is pumped into the wastewater tank through a wastewater pump;

[0139] (3) Open the flow regulating 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 regulating valve, the flow rate of the oily sewage is controlled to be 0.1-0.5m / s relative to the modified membrane with a filling volume of 300L. 3 / h.

[0140] The specific operating conditions are shown in Table 6.

[0141] After stable operation, water from the production tank was collected, its oil content was measured, and the oil removal rate was calculated. The results are shown in Table 6.

[0142] The loading ratio is the ratio of the loading volume of the cross-linked modified omentum to the volume of the oil-water separator, and the feed rate is the feed rate relative to a loading volume of 300 L of the cross-linked modified omentum.

[0143] The tensile strength of the products prepared in Examples 1-9 and Comparative Examples 1-2 was measured respectively. The results are shown in Table 6.

[0144] Table 6

[0145]

[0146] The results in Table 6 show that the cross-linked modified omentum prepared using the technical solution of the present invention still achieved a high oil removal rate during oil-water separation even after six months of operation, demonstrating that the omentum prepared using the technical solution of the present invention can ensure long-term effectiveness. Furthermore, a comparison with the data from Comparative Example 1 reveals that the tensile strength of the omentum prepared using the present invention is similar to that of the unmodified omentum in Comparative Example 1, but with a superior oil removal effect. This demonstrates that the technical solution of the present invention can achieve even higher oil-water separation efficiency without compromising the mechanical properties of the underlying material.

[0147] Furthermore, the omentum prepared using the technical solution of the present invention has a simple preparation process and is suitable for industrial-scale production. Furthermore, the oil-water separation process using the device of the present invention is safe and explosion-proof, has low operating costs, high efficiency, and does not generate waste residue or cause secondary pollution.

[0148] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cross-linked modified omentum, characterized in that: The method includes: (1) melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers; (2) modifying the polypropylene fiber using a hydrophilic modified compound under the action of a crosslinking agent to obtain a modified polypropylene fiber; (3) forming a web from the modified polypropylene fiber to obtain a cross-linked modified web membrane having a three-dimensional network; In step (2), the modification method comprises: immersing the polypropylene fiber in a first crosslinking agent solution for pretreatment to obtain a polypropylene fiber with a surface covered with a crosslinking agent; immersing the polypropylene fiber with a surface covered with a crosslinking agent in a hydrophilic modification compound solution for deposition to obtain deposited polypropylene fiber; immersing the deposited polypropylene fiber in a second crosslinking agent solution and performing a crosslinking reaction under the action of a catalyst to obtain a modified polypropylene fiber; The first cross-linking agent and the second cross-linking agent are each independently selected from at least one of glutaraldehyde, formaldehyde, succinaldehyde, glyoxal, ethylene glycol bisglycidyl ether and epichlorohydrin; The hydrophilic modification compound is selected from at least one of polyethyleneimine, polylysine, polyarginine, ethanolamine, histidine, chitosan quaternary ammonium salt, and carboxymethyl chitosan; The amount of the first cross-linking agent in the first cross-linking agent solution is 100-500 g relative to 1 kg of polypropylene fiber; The pretreatment conditions include: time of 24-72h, temperature of 25-75°C; The amount of the second cross-linking agent in the second cross-linking agent solution is 50-200 g relative to 1 kg of polypropylene fiber; The catalyst is selected from any one of sulfuric acid, hydrochloric acid or nitric acid; Relative to 1 kg of polypropylene fiber, the amount of the catalyst is 5-50 g; The conditions of the cross-linking reaction include: time of 1-6 hours and temperature of 25-75°C.

2. The method according to claim 1, wherein In step (1), according to the ASTM D1238-13 method, the polypropylene has a melt index of 100-1000 g / 10 min at a temperature of 230° C. and a load weight of 2.16 kg; And / or, the antioxidant is selected from at least one of tris(2,4-di-tert-butylphenyl)phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; and / or, the polypropylene and antioxidant are used in a ratio of 9-99:1 by weight; and / or, the melting temperature is 175-210° C.; And / or, the spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution; And / or, the spinning conditions are such that the diameter of the polypropylene fiber is 10-40 μm.

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

4. The method according to claim 1, wherein The molecular weight of the hydrophilic modified compound is 61-20000 g / mol; and / or, the mass ratio of the polypropylene fiber to the hydrophilic modification compound in the hydrophilic modification compound solution is 100:5-30; And / or, the deposition conditions include: a time of 12-48 hours and a temperature of 25-75°C.

5. The method according to claim 1, wherein The web forming method includes: carding, needle punching, and heat sealing in sequence; And / or, the conditions of the web forming process are such that the weight of the cross-linked modified web is 150-650 g / m 2 , thickness is 25-80mm.

6. The method according to claim 1, wherein The conditions of the web forming process make the weight of the cross-linked modified web film be 200-500 g / m 2 , thickness is 30-60mm.

7. A cross-linked modified omentum prepared by the method according to any one of claims 1 to 6.

8. The cross-linked modified omentum according to claim 7, wherein The omentum has a three-dimensional network structure; and / or, in the omentum, the content ratio of the structural unit derived from polypropylene to the structural unit derived from the hydrophilic modified compound is 100:5-30; And / or, the gram weight of the omentum is 150-650g / m 2 , thickness is 25-80mm; And / or, the omentum further contains an antioxidant; And / or, in the omentum, the content ratio of the polypropylene to the antioxidant is 9-99:1 by weight.

9. The cross-linked modified omentum according to claim 7, wherein The weight of the omentum is 200-500g / m 2 , thickness is 30-60mm.

10. Use of the cross-linked modified omentum according to any one of claims 7 to 9 in treating oily wastewater.

11. A device for treating oily wastewater, comprising, in order according to the flow 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 cross-linked modified mesh membrane according to any one of claims 7 to 9 for oil-water separation; The oil-water separator is further connected to a water production tank and an oil collecting tank respectively. The water production tank is used to receive the water phase from the oil-water separator, and the oil collecting tank is used to receive the oil phase from the oil-water separator.

12. A method for treating oily wastewater, characterized in that: The method is carried out in the device according to claim 11, and comprises: introducing the oily wastewater in the liquid storage tank into the oil-water separator to separate the oil and water.

13. The processing method according to claim 12, wherein: In the oil-water separator, the ratio of the filling volume of the cross-linked modified omentum to the volume of the oil-water separator is 1:2-4.

14. The processing method according to claim 12, wherein: In the oil-water separator, relative to the cross-linked modified membrane with a filling volume of 300L, the oily wastewater flow rate is 0.1-0.5m 3 / h.

15. The processing method according to claim 12, wherein: The temperature of the oily wastewater is 40-60°C.

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