Membrane with interception function, preparation method, application, and device and method for treating oily wastewater

Abstract

The present invention relates to the field of oil-water separation materials, and more particularly to a mesh with an intercepting function, a preparation method, and an apparatus and method for its application and treatment of oily wastewater. The mesh is composed of polypropylene combined with inorganic nanoparticles, and has a three-dimensional porous network structure; wherein the gram weight of the mesh is not less than 100g / m 2 The thickness is not less than 20mm. The mesh has the characteristics of high oil removal rate, high flux and low energy consumption, i.e., two highs and one low. When the mesh is used for oil-water separation, the operation is simple, the operating cost is low, the effect is stable, and the long-term operation can ensure that the water output index can be stably met.

Description

Technical Field

[0001] The invention relates to the field of oil-water separation materials, and in particular to a mesh membrane with an interception function, a preparation method thereof, and an application and a device and method for treating oily wastewater. Background Art

[0002] Oily wastewater is a large, widespread, and severely harmful wastewater. Oil enters the aquatic environment through various pathways, forming oily wastewater. Oily wastewater originates from a wide range of sources, with industrial production generating a particularly large volume. Oily wastewater in the petrochemical industry includes oilfield water, well flushing water, tank separation water, refinery wastewater, and petrochemical plant wastewater. my country's refining industry alone produces hundreds of millions of tons of oily wastewater annually. This oily wastewater has a complex composition. Besides oil, it also contains impurities such as solid particles, salts, and various organic compounds, and has a high chemical oxygen demand (COD). Discharged directly without treatment can severely pollute the environment. 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 when treating oily wastewater. However, traditional two-dimensional porous polymer separation membranes have a trade-off effect in flux and selectivity when treating oily wastewater, especially for oil-water emulsion separation. It is difficult to achieve both high permeability and high selectivity. In addition, the flux decays rapidly, the separation efficiency is not high, external driving pressure is required, it is easy to cause fouling, the types of oily wastewater that can be treated are limited, and it is impossible to simultaneously separate water-in-oil and oil-in-water emulsions.

[0003] In order to overcome the shortcomings of traditional two-dimensional structural polymer membranes, some studies have used silk screen, organic microfiltration membranes, etc. as substrates, and dip-coated super-hydrophilic materials on them to construct micro-nano structures to form mesh membranes. This can effectively overcome the weaknesses of two-dimensional symmetrical membranes such as poor pressure resistance, rapid flux attenuation, and low separation efficiency. However, the preparation method of this type of mesh membrane is complicated, the service life is short, and the resistance to expansion and chemicals is poor. It cannot adapt to the separation of oil-water mixtures in complex chemical environments, and it is difficult to achieve large-scale industrial applications.

[0004] Therefore, it is necessary to develop an oil-water separation material with high separation efficiency, high flux, low energy consumption, and stable combination of modified substances and main materials. The preparation process of this material is simple, and it can ensure safety during use, low energy consumption, low operating cost, no secondary pollution, and long-term operation can also ensure that the water 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 mesh with interception function and a preparation method as well as an apparatus and method for applying and treating oily wastewater. The mesh has a three-dimensional porous network structure and has the characteristics of high oil removal rate, high flux and low energy consumption, i.e., two highs and one low. When the mesh is used for oil-water separation, the operation is simple and the effect is stable. Long-term operation can also ensure that the effluent indicators are stable and meet the standards, i.e., it is effective for a long time.

[0006] In order to achieve the above object, the present invention provides a mesh with a retention function, wherein the mesh is composed of polypropylene combined with inorganic nanoparticles, and the mesh has a three-dimensional porous network structure; wherein the gram weight of the mesh is not less than 100g / m 2 , thickness not less than 20mm.

[0007] A second aspect of the present invention provides a method for preparing an omentum having an interception function, the method comprising:

[0008] (1) melting polypropylene and inorganic nanoparticles to obtain a spinning solution;

[0009] (2) spinning the spinning solution to obtain polypropylene fibers;

[0010] (3) The polypropylene fibers are subjected to a web-forming process to obtain the web membrane having a three-dimensional network structure and a retention function.

[0011] The third aspect of the present invention provides a mesh membrane with interception function prepared by the method as described above.

[0012] A fourth aspect of the present invention provides a use of the omentum with interception function provided by the first aspect or the third aspect of the present invention in treating oily wastewater.

[0013] A fifth 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] The liquid storage tank is used to store oily wastewater; the oil-water separator is filled with a membrane with a retention function as provided in the first or third aspect of the present invention, 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 sixth 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 mesh with interception function provided by the present invention increases the critical penetration pressure of oil. When oily wastewater passes through the mesh, water can pass through it first and smoothly with a higher separation flux, while the oil is intercepted, that is, it can intercept oil and guide water to achieve oil-water separation, and has the characteristics of high oil removal rate, high flux, and low energy consumption, that is, two highs and one low.

[0019] 2. The retention membrane provided by the present invention features uniform dispersion of inorganic nanoparticles in polypropylene, resulting in a high loading, significantly improving the membrane's hydrophilicity and oil removal efficiency. Furthermore, the membrane exhibits a three-dimensional porous network structure with appropriate pore size and porosity, making it easy to assemble and integrate with other processes.

[0020] 3. The oily wastewater treatment device provided by the present invention has a compact structure, small size, and is fully enclosed. When it is used for the treatment of oily wastewater, the treatment process is safe and explosion-proof, with a small pressure drop, simple operation, low operating cost, no secondary pollution, stable effect, and long-term operation can ensure that the effluent indicators are stable and meet the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a SEM image of the omentum prepared in Example 3 of the present invention;

[0022] Figure 2 The invention provides a device for treating oily wastewater.

[0023] Description of Reference Numerals

[0024] 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

[0025] 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.

[0026] 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.

[0027] In a first aspect, the present invention provides a mesh membrane with a retention function, wherein the mesh membrane is composed of polypropylene combined with inorganic nanoparticles, and the mesh membrane has a three-dimensional porous network structure;

[0028] The weight of the mesh is not less than 100 g / m 2 , thickness not less than 20mm.

[0029] For example, the weight of the web can be 100-700 g / m 2 (100g / m 2 , 200g / m 2 , 300g / m 2 , 400g / m 2 , 500g / m 2 , 600g / m 2 , 700g / m 2 and a value within the range formed by any two of the above values), the thickness of the omentum can be 20-70 mm (for example, it can be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm and a value within the range formed by any two of the above values).

[0030] The inorganic nanoparticles can regulate the oil-water wetting balance of the membrane, enhancing the hydrophilicity of the membrane. The membrane has a three-dimensional porous network structure, i.e., a three-dimensional porous network structure that is interconnected. The inventors of the present invention have discovered in their research that when the membrane is used for oil-water separation, after the oily wastewater comes into contact with the membrane, water quickly spreads and adheres to the membrane surface or pores to form a hydration layer. This hydration layer has a great adhesion to the membrane surface, thereby preventing oil droplets from contacting the membrane surface. At the same time, because the density of water is generally greater than that of oil, it is located in the lower layer. Due to the incompatibility and huge surface tension between water and oil, the oil cannot curl into a sphere on the water surface and forms a sheet. As the oil increases, an oil phase is formed, which separates the oil and water. If a small amount of oil droplets penetrate the pores of the surface membrane into the three-dimensional inner structure of the mesh, the coalescence of the polymer fibers that make up the mesh can cause the oil droplets to contact and aggregate, eventually forming oil droplets of sufficient diameter. These droplets, under the buoyancy of the water and the force of the current, fall off and float up to form a continuous oil phase, achieving the purpose of oil removal. Compared with traditional two-dimensional oil-water separation materials, the mesh with a three-dimensional porous network structure provided by the present invention can achieve higher oil-water separation efficiency, that is, higher oil removal rate.

[0031] In addition, the inventors of the present invention also found in their research that compared with conventional separation membranes such as ultrafiltration membranes, the mesh membrane with interception function of the present invention has a fast separation speed and high flux, and can achieve water diversion and oil interception with low energy consumption by relying on the static pressure of the liquid column and other effects.

[0032] According to the present invention, even if the above-mentioned weight and thickness are met, the purpose of the present invention can be achieved. In order to further improve the oil removal rate of the mesh, preferably, the weight of the mesh is not less than 200g / m 2 , thickness is not less than 30mm; more preferably, the gram weight of the omentum is 200-600g / m 2 , thickness is 30-60mm.

[0033] According to the present invention, in order to further improve the oil removal rate of the omentum, preferably, the pore size of the omentum is not less than 5 μm (for example, it can be 5-75 μm), more preferably 10-65 μm, and the porosity is not less than 45% by volume (for example, it can be 45-95% by volume), more preferably 60-90% by volume. It is understood that when the above ranges, especially the pore size and porosity ranges, are met, the critical penetration pressure of the oil can be further increased, further ensuring a higher oil removal rate and flux, and better meeting the scale requirements of industrial applications.

[0034] According to the present invention, to further improve the oil removal rate of the omentum, the polypropylene preferably has a melt index of 100-1200 g / 10 min at a temperature of 230°C and a load of 2.16 kg, as determined by ASTM D1238-13. The inventors have discovered that polypropylene within this melt index range exhibits excellent flowability, processability, and mechanical properties of the resulting omentum, further enhancing the omentum's oil removal rate.

[0035] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the content ratio of polypropylene to inorganic nanoparticles in the omentum is 9-100:1 by weight.

[0036] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the average particle size of the inorganic nanoparticles is 20-200nm (for example, it can be 20nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 200nm and a value within the range formed by any two of the above values).

[0037] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, the inorganic nanoparticles are selected from at least one of nano-silicon dioxide, nano-titanium dioxide, nano-silicon carbide and nano-calcium carbonate.

[0038] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the inorganic nanoparticles are combined with polypropylene through a coupling agent. The inventors of the present invention have found in research that when a coupling agent is used, the alkoxy group in the coupling agent reacts with the hydroxyl group present on the surface of the inorganic nanoparticles, which can make the coupling agent and the nanoparticle surface combine in the form of a chemical bond, and can also be cross-linked or transesterified with polypropylene, making the inorganic nanoparticles and polypropylene combination more stable. The addition of the coupling agent can also make the inorganic nanoparticles more evenly dispersed in the polypropylene, have better compatibility with polypropylene, have a higher filling amount, and can further enhance the hydrophilicity and mechanical properties of the polypropylene separation membrane, further improve the oil removal rate of the omentum, and further ensure the stability of the effect.

[0039] According to the present invention, preferably, the coupling agent is selected from at least one of a silane coupling agent and a titanate coupling agent.

[0040] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the silane coupling agent is selected from at least one of n-octyltriethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, phenyltrichlorosilane, methylphenyldichlorosilane, and vinyltriacetoxysilane.

[0041] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the titanate coupling agent is selected from at least one of triisostearoyl isopropyl titanate, triisopropyl dioctyl pyrophosphate acyloxy titanate and triisopropyl dodecylbenzenesulfonyl titanate.

[0042] In a second aspect, the present invention provides a method for preparing an omentum having a retention function, the method comprising:

[0043] (1) melting polypropylene and inorganic nanoparticles to obtain a spinning solution;

[0044] (2) spinning the spinning solution to obtain polypropylene fibers;

[0045] (3) The polypropylene fibers are subjected to a web-forming process to obtain the web membrane having a three-dimensional network structure and a retention function.

[0046] According to the present invention, preferably, before melting, the method further comprises: drying the polypropylene to remove any moisture that may be adsorbed therein. The specific method and conditions for drying are not particularly limited. Preferably, the drying conditions include: a temperature of 70-90°C and a drying time of 2-6 hours.

[0047] According to the present invention, in order to further improve the oil removal rate of the omentum, preferably, 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 100-1200 g / 10 min.

[0048] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, and / or, by weight, the amount of polypropylene and inorganic nanoparticles is such that, by weight, the content ratio of polypropylene to inorganic nanoparticles in the omentum is 9-100:1;

[0049] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the average particle size of the inorganic nanoparticles is 20-200 nm.

[0050] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the inorganic nanoparticles are selected from at least one of nano-silicon dioxide, nano-titanium dioxide, nano-silicon carbide, and nano-calcium carbonate.

[0051] According to the present invention, in order to further improve the oil removal rate of the omentum and further ensure long-term effectiveness, preferably, the inorganic nanoparticles are combined with polypropylene through a coupling agent.

[0052] According to the present invention, preferably, the coupling agent is selected from at least one of a silane coupling agent and a titanate coupling agent.

[0053] According to the present invention, preferably, the silane coupling agent is selected from at least one of n-octyltriethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, phenyltrichlorosilane, methylphenyldichlorosilane, and vinyltriacetoxysilane;

[0054] According to the present invention, preferably, the titanate coupling agent is selected from at least one of triisostearoyl isopropyl titanate, triisopropyl dioctyl pyrophosphate acyloxy titanate and triisopropyl dodecylbenzenesulfonyl titanate.

[0055] It is understood that the use of an antioxidant or not can be selected according to the requirements of the omentum to be prepared. The specific composition and dosage of the antioxidant can be conventionally selected in the art and will not be described in detail here.

[0056] According to the present invention, preferably, the melting temperature is 175-230°C (for example, 175°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C); it can be understood that the melting time is not particularly limited as long as it can ensure that the polypropylene and inorganic nanoparticles can be melted as much as possible.

[0057] According to the present invention, in order to make the spinning solution more uniform and improve the oil removal rate of the prepared mesh, preferably, the method further comprises: stirring and degassing after melting.

[0058] According to the present invention, preferably, the stirring conditions include: stirring in an inert gas atmosphere for 1-4 hours, wherein the inert gas is a gas that does not react with the molten material, such as nitrogen.

[0059] According to the present invention, the degassing conditions include: a temperature of 175-230° C. and standing for 1-2 hours.

[0060] 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.

[0061] According to the present invention, preferably, the spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution.

[0062] 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).

[0063] According to the present invention, preferably, the extrusion conditions include: a temperature of 175-230°C (for example, 175, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C). The extrusion device is not particularly limited, and preferably, the extrusion is carried out by feeding the spinning solution 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 175-230°C.

[0064] According to the present invention, preferably, the spinning conditions include: a spinneret aperture of 0.05-2 mm, and a temperature of 170-220°C.

[0065] 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.

[0066] According to the present invention, preferably, the cooling condition includes: using air cooling, and the air temperature is 5-20°C.

[0067] According to the present invention, preferably, in order to further improve the oil removal rate of the web and further ensure long-term effectiveness, the web forming process preferably includes: carding, needling, and heat-sealing reinforcement in sequence. It can be understood that the carding process is to use a carding machine to comb the fibers so that they are arranged and formed; the needling process 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 reinforcement is to use a hot melt adhesive to further fix the fibers into shape to form the web.

[0068] According to the present invention, preferably, the conditions of the web forming process are such that the weight of the web is not less than 100 g / m 2 , preferably not less than 200g / m 2 , thickness is not less than 20mm, preferably not less than 30mm.

[0069] According to the present invention, preferably, the conditions of the reticulation treatment are such that the pore size of the reticulation is not less than 5 μm, preferably 10-65 μm, and the porosity is not less than 45% by volume, preferably 60-90% by volume.

[0070] In a third aspect, the present invention provides a mesh membrane with interception function prepared by the method described above.

[0071] In a fourth aspect, the present invention provides a use of a mesh membrane with interception function as provided in the first or third aspect of the present invention in treating oily wastewater.

[0072] In a fifth 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;

[0073] The liquid storage tank is used to store oily wastewater; the oil-water separator is filled with a membrane with a retention function as provided in the first or third aspect of the present invention, for oil-water separation;

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 lead the water phase obtained after membrane separation 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 membrane separation out of the oil-water separator and into the oil collection tank.

[0079] It is understood that when oily wastewater is separated through the oil-water separator, the material filled therein has hydrophilic and oleophobic properties. Under the combined effects of selective retention and coalescence separation, the water phase will pass through the membrane and enter the lower part of the oil-water separator, while the oil phase will be retained 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.

[0080] 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.

[0081] In a sixth 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 for oil-water separation.

[0082] According to the present invention, preferably, in the oil-water separator, the ratio of the filling volume of the mesh membrane with interception function to the volume of the oil-water separator is 1:2-4.

[0083] The packing volume may be the volume of the omentum packed under conventional packing operations in the art, for example, the volume of the omentum packed into the oil-water separator bed layer by layer compaction at 0.2 MPa.

[0084] According to the present invention, preferably, in the oil-water separator, relative to the mesh membrane with interception function with a filling volume of 300L, the oily wastewater inlet speed is 0.1-0.5m 3 / h;

[0085] According to the present invention, preferably, the temperature of the oily wastewater is 40-60°C.

[0086] According to a particularly preferred embodiment of the present invention, the preparation of the omentum with interception function and the treatment of oily wastewater are carried out according to the following method:

[0087] (1) Polypropylene with a melt index of 550-650 g / 10 min is first dried at 83-88° C. for 3.8-4.2 h; nano-calcium carbonate treated with a methylphenyldichlorosilane coupling agent is then mixed with the dried polypropylene, wherein the amount of polypropylene and the inorganic nanoparticles is such that, by weight, the amount ratio of polypropylene to nano-calcium carbonate in the web is 13-20:1, and the particle size of the nanoparticles is 25-35 nm; and the mixture is melted at a melting temperature of 205-212° C.; the mixture is stirred at nitrogen for 1.8-2.2 h, and after stopping the stirring, the mixture is allowed to stand at 205-212° C. for degassing for 1.8-2 h to obtain a spinning solution.

[0088] After the spinning solution is filtered through a filter screen, it is fed into a screw extruder through a pipeline for extrusion at a temperature of 205-212° C.; the spinning solution is then spun at a temperature of 198-202° C. and a spinneret aperture of 0.8-1.2 mm; the solution is then stretched by airflow at a temperature of 143-146° C. and a spinning speed of 130-180 m / min; and the solution is then cooled by air at a temperature of 9-12° C. to obtain polypropylene fibers.

[0089] The polypropylene fibers are combed, needled, and heat-sealed to obtain the mesh having a three-dimensional network structure and a retention function. The mesh forming process conditions are such that the mesh has a grammage of 400-430 g / m 2 The thickness of the omentum is 45-55 mm, the pore size of the omentum is 25-30 μm, and the porosity of the omentum is 72-74% by volume.

[0090] (2) The mesh membrane is compacted and loaded into the bed layer of the oil-water separator in layers at 0.2 MPa, with the volume ratio of the mesh membrane to the volume of the oil-water separator being 1:2.5-3.5;

[0091] (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;

[0092] (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, control the water flow rate at 0.1-0.2m 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.

[0093] The present invention will be described in detail below by way of examples. In the following examples and test examples:

[0094] The polypropylene melt index is measured using the ASTM D1238-13 method at a temperature of 230° C. and a load weight of 2.16 kg.

[0095] 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 ).

[0096] The diameter of polypropylene fibers was measured using an XL-30 field emission scanning electron microscope.

[0097] 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.

[0098] The oil removal rate is calculated as follows:

[0099] Wherein, C0 represents the oil content of the oily wastewater in the wastewater tank, in mg / L;

[0100] C represents the oil content of the water phase in the water production tank, in mg / L.

[0101] Furthermore, unless otherwise specified, the materials described are all commercially available.

[0102] like Figure 2 As 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 from 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 also connected to the sewage inlet of oil-water separator 7 via a pipeline and is used to pump the wastewater from sewage tank 3 into oil-water separator 7 for treatment. Oil-water separator 7 is equipped with a membrane with a retention function to treat the oily wastewater, specifically separating 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.

[0103] Examples 1-10 and Comparative Examples 1-2

[0104] (1) Polypropylene is dried first, and then added into a spinning kettle with a stirring device to mix with inorganic nanoparticles and melted. Then, the mixture is stirred under nitrogen flow. After stopping the stirring, the mixture is allowed to stand for degassing to obtain a spinning solution.

[0105] (2) After the spinning solution is filtered through the filter screen, it is input into the screw extruder through the pipeline and extruded, and then spun through the spinneret of the spinning assembly through the metering pump, and then stretched by the air flow to form nascent fibers. The nascent fibers are cooled by cooling air to obtain polypropylene fibers with uniform thickness.

[0106] (3) Polypropylene fibers are taken, and after being combed into a net, needle-punched, and heat-sealed for reinforcement, the net membrane having a three-dimensional network structure and a retention function is obtained.

[0107] The condition parameters of each step and each material parameter of Examples 1-10 and Comparative Examples 1-2, as well as the gram weight, thickness, pore size and porosity of the omentum are shown in Tables 1 and 2.

[0108] Table 1

[0109]

[0110] Table 2

[0111]

[0112] Table 3

[0113]

[0114]

[0115] Among them, Comparative Example 1 is carried out according to the method of Example 3, except that inorganic nanoparticles are not added during melting; Comparative Example 2 is carried out according to the method of Example 3, except that the polypropylene fiber is not subjected to a web forming process; m (polypropylene resin: inorganic nanoparticles) refers to the amount of polypropylene and inorganic nanoparticles used so that, by weight, the content ratio of polypropylene and inorganic nanoparticles in the web.

[0116] Furthermore, the SEM image of the omentum with interception function prepared in Example 3 is as follows: Figure 1 shown.

[0117] Test Case

[0118] The oily wastewater from a certain refinery was measured to have a pH of 7.5 and an oil content of 16,750 mg / L.

[0119] Take the omentum with interception function prepared in Examples 1-10 and Comparative Examples 1-2, which have been used for more than 6 months before this test, and Figure 2 The oily wastewater is treated in the oily wastewater treatment device shown.

[0120] The specific method is:

[0121] (1) The products prepared in Examples 1-10 and Comparative Examples 1-2 were respectively compacted and loaded into the bed of an oil-water separator in layers at 0.2 MPa.

[0122] (2) Pump the oily wastewater in the storage tank at a temperature of 40-60°C into the wastewater tank through a wastewater pump;

[0123] (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, control the feed speed at 0.1-0.5m 3 / h.

[0124] The specific operating conditions are shown in Table 4.

[0125] 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 4.

[0126] The filling ratio is the ratio of the filling volume of the membrane with interception function to the volume of the oil-water separator, and the feed rate is the feed rate of the membrane with interception function relative to a filling volume of 300L.

[0127] Table 4

[0128]

[0129]

[0130] The results in Table 4 show that the retaining membrane prepared using the technical solution of the present invention still achieved a high oil removal rate during oil-water separation after six months of operation, indicating that the membrane prepared using the technical solution of the present invention can ensure long-term effectiveness. Comparative Examples 1-2, which did not use the technical solution of the present invention, showed inferior results.

[0131] Furthermore, the preparation of the omentum using the technical solution of the present invention is simple and suitable for industrial promotion. Furthermore, the use of the technical solution of the present invention for oil-water separation has low energy consumption, does not generate waste residue, and does not cause secondary pollution. Furthermore, the separation speed is fast and the throughput is high. By utilizing the effects of the static pressure of the liquid column, water diversion and oil interception can be achieved with low energy consumption.

[0132] 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 an omentum with a retention function, characterized in that: The method includes: (1) melting polypropylene and inorganic nanoparticles to obtain a spinning solution; (2) spinning the spinning solution to obtain polypropylene fibers; (3) forming the polypropylene fibers into a web to obtain the web having a three-dimensional network structure and a retention function; 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 100-1200 g / 10 min; The netting process conditions are such that the netting weight is not less than 100 g / m 2 , thickness not less than 20mm; Wherein, in step (2), the spinning method further comprises: sequentially extruding, spinning, stretching and cooling the spinning solution; Wherein, the extrusion conditions include: temperature of 175-230°C; The spinning conditions include: a spinneret aperture of 0.05-2 mm and a temperature of 170-220° C. The stretching conditions include: air flow stretching, the air flow temperature is 120-150° C., and the stretching spinning speed is 100-400 m / min; The cooling conditions include: using air cooling, the air temperature is 5-20°C; Wherein, the inorganic nanoparticles are combined with polypropylene through a coupling agent.

2. The method according to claim 1, wherein The amounts of polypropylene and inorganic nanoparticles used are such that, by weight, the content ratio of polypropylene to inorganic nanoparticles in the omentum is 9-100:

1.

3. The method according to claim 1, wherein The average particle size of the inorganic nanoparticles is 20-200 nm.

4. The method according to claim 1, wherein The inorganic nanoparticles are selected from at least one of nano-silicon dioxide, nano-titanium dioxide, nano-silicon carbide and nano-calcium carbonate.

5. The method according to claim 1, wherein The coupling agent is selected from at least one of a silane coupling agent and a titanate coupling agent.

6. The method according to claim 5, wherein: The silane coupling agent is selected from at least one of n-octyltriethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, phenyltrichlorosilane, methylphenyldichlorosilane, and vinyltriacetoxysilane.

7. The method according to claim 5, wherein: The titanate coupling agent is selected from at least one of triisostearoyl isopropyl titanate, triisopropyl dioctyl pyrophosphate acyloxy titanate and triisopropyl dodecylbenzenesulfonyl titanate.

8. The method according to claim 1, wherein In step (1), the melting temperature is 175-230°C.

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

10. The method according to claim 9, wherein: The stirring conditions include: stirring in an inert gas atmosphere for 1-4 hours.

11. The method according to claim 9, wherein: The degassing conditions include: temperature of 175-230° C., and standing for 1-2 hours.

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

13. The method according to claim 1, wherein In step (3), the web forming process comprises: carding, needling and heat sealing in sequence.

14. The method according to claim 1, wherein The conditions of the web forming process are such that the weight of the web is not less than 200 g / m 2 , thickness not less than 30mm.

15. The method according to claim 1, wherein The conditions of the web forming treatment are such that the pore size of the web is not less than 5 μm and the porosity is not less than 45% by volume.

16. The method according to claim 15, wherein The conditions of the reticulation treatment are such that the pore size of the reticulation membrane is 10-65 μm and the porosity is 60-90% by volume.

17. A mesh membrane with interception function prepared by the method according to any one of claims 1 to 16.

18. Use of the omentum with interception function according to claim 17 in treating oily wastewater.

19. 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 mesh membrane with interception function according to claim 17 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.

20. A method for treating oily wastewater, characterized in that: The method is carried out in the device according to claim 19, and comprises: introducing the oily wastewater in the liquid storage tank into the oil-water separator to separate the oil and water.

21. The method according to claim 20, wherein In the oil-water separator, the ratio of the filling volume of the membrane with interception function to the volume of the oil-water separator is 1:2-4.

22. The method according to claim 20, wherein In the oil-water separator, the oily wastewater flow rate is 0.1-0.5m / s relative to the membrane with interception function with a filling volume of 300L. 3 / h.

23. The method according to claim 20, wherein The temperature of oily wastewater is 40-60℃.

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