Surface modified mesh membrane and preparation method and application thereof, and treatment device and treatment method for oily wastewater

Abstract

The present invention relates to the field of modified materials, and particularly to a surface-modified mesh and its preparation method, application, a sewage-containing treatment device and a treatment method. The surface-modified mesh has a three-dimensional network structure, and the material of the surface-modified mesh is polypropylene associated with a surfactant on the surface; wherein, the grammage of the surface-modified mesh is not less than 100 g / m<supgt;2< / supgt;, the thickness is not less than 25 mm, and the porosity is greater than 50% by volume. The surface-modified mesh has the characteristics of high oil removal rate, high flux and low energy consumption, and does not affect the inherent properties of the bulk material such as physical strength, chemical stability, radiation resistance, etc. When the surface-modified mesh is used for oil-water separation, the operation is simple, the energy consumption is low, the operation cost is low, no secondary pollution will be caused, and the effluent index can be stably up to the standard during long-term operation, that is, it is effective in the long term.

Description

Technical Field

[0001] The present invention relates to the field of modified materials, and particularly to a surface-modified mesh, a preparation method and application thereof, an oil-containing sewage treatment device and a treatment method. Background Art

[0002] The treatment of oil-containing sewage is extremely difficult, with low efficiency and high cost. It is one of the industrial wastewaters that are difficult to treat nowadays. The existing oil-containing sewage treatment technologies have disadvantages such as long time, large equipment volume, fast equipment corrosion rate, and use of a large amount of chemical agents. Therefore, new technologies need to be developed for treatment.

[0003] The treatment of oil-containing sewage by membrane separation technology is based on the microporous sieving effect of the membrane and the special wetting performance of the membrane for separation. This method has the advantages of simplicity, high efficiency, flexible and simple operation, low environmental pollution, strong versatility, etc., and is an important future development direction of oil-water separation membranes. However, in the treatment of oil-containing sewage, especially in the separation of oil-water emulsions, there is a trade-off effect between flux and selectivity for traditional two-dimensional porous polymer separation membranes, making it difficult to have both high permeability and high selectivity. The flux decays relatively fast, the separation efficiency is not high, an external driving pressure is required, fouling is easy to occur, and the types of oil-containing sewage that can be treated are limited, etc. To overcome the deficiencies of traditional two-dimensional structure polymer membranes, some researchers use wire meshes, organic microfiltration membranes, etc. as substrates, and dip-coat or paint superhydrophilic substances on them to construct micro-nano structures to form meshes, which can effectively overcome the weaknesses of two-dimensional symmetric membranes such as low pressure resistance, fast flux decay, and low separation efficiency. However, the preparation methods of such meshes are complex, the service life is short, and the resistance to swelling and chemical agents is poor, and they cannot adapt to the separation of oil-water mixtures in complex chemical environments, making it 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, and low energy consumption. When using this material for oil-water separation, the operation is simple, the operating cost is low, no secondary pollution is caused, and the effluent index can be stably up to standard during long-term operation. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above problems existing in the prior art, and provide a surface-modified mesh, a preparation method and application thereof, an oil-containing sewage treatment device and a treatment method. The surface-modified mesh has the characteristics of high oil removal rate, high flux, and low energy consumption. When using this material for oil-water separation, the operation is simple, the energy consumption is low, the operating cost is low, no secondary pollution is caused, and the effluent index can be stably up to standard during long-term operation.

[0006] To achieve the above purpose, in the first aspect of the present invention, a surface-modified mesh is provided. The surface-modified mesh has a three-dimensional network structure, and the material of the surface-modified mesh is polypropylene associated with a surfactant on the surface;

[0007] Among them, the grammage of the surface-modified web is not less than 100 g / m 2 , the thickness is not less than 25 mm, and the porosity is greater than 50% by volume.

[0008] The second aspect of the present invention provides a method for preparing a surface-modified web, the method comprising:

[0009] (1) Melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers;

[0010] (2) Immersing the polypropylene fibers in a surfactant solution for surface modification to obtain surface-modified polypropylene fibers;

[0011] (3) Conducting a web-forming treatment on the surface-modified polypropylene fibers to obtain a surface-modified web having a three-dimensional network structure.

[0012] The third aspect of the present invention provides a surface-modified web prepared by the method as described above.

[0013] The fourth aspect of the present invention provides the application of the surface-modified web provided in the first aspect or the third aspect of the present invention in treating oily sewage.

[0014] The fifth aspect of the present invention provides a device for treating oily sewage. According to the flow direction of the material, the treatment device sequentially includes: a storage tank and an oil-water separator;

[0015] Among them, the storage tank is used for storing oily sewage; the oil-water separator is filled with the surface-modified web provided in the first aspect or the third aspect of the present invention for oil-water separation;

[0016] Among them, the oil-water separator is also respectively connected to a water production tank and an oil collection tank. The water production tank is used for receiving the water phase from the oil-water separator, and the oil collection tank is used for receiving the oil phase from the oil-water separator.

[0017] The sixth aspect of the present invention provides a method for treating oily sewage. The method is carried out in the device as described above, and the method includes: introducing the oily sewage in the storage tank into the oil-water separator for oil-water separation.

[0018] Through the above technical solutions, the present invention can achieve the following beneficial effects:

[0019] 1. The surface-modified web provided by the present invention has a three-dimensional network structure and has the function of water conduction and oil interception. The surface-modified web of the present invention improves the critical penetration pressure of oil. When oily sewage passes through the web, water can pass through smoothly and has a high separation flux. Compared with traditional two-dimensional polymer membranes, the surface-modified web of the present invention has the characteristics of high separation efficiency, high flux, and low energy consumption.

[0020] 2. The surface-modified web provided by the present invention does not affect the inherent properties of the matrix material such as physical strength, chemical stability, and radiation resistance. The preparation process is simple, and the modification process and conditions are easy to control. After impregnation and drying treatments, the hydrophilic active substances are firmly adsorbed on the fiber surface, not easily lost or volatilized, and can achieve long-term effectiveness. If it is found that the selective retention ability of the web decreases during the oil removal process, the web can be washed and then the above-mentioned impregnation / drying method can be used to restore its function. No large amount of harmful waste liquid is generated during the entire modification process, which is environmentally friendly and pollution-free, energy-saving and efficient, and the hydrophilicity is maintained for a long time, suitable for industrial production.

[0021] 3. The oil-containing sewage treatment device provided by the present invention has a compact structure, small volume, and is fully enclosed; when it is used for treating oil-containing sewage, the treatment process is safe and explosion-proof, with a small pressure drop, low energy consumption, low operating cost, and the recovered waste oil can be recycled and reused, without generating any waste residue, and the effluent index can be stably up to standard even during long-term operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is an oil-containing sewage treatment device provided by the present invention.

[0023] DESCRIPTION OF THE REFERENCE NUMERALS

[0024] 1 - liquid storage tank; 2 - sewage pump; 3 - sewage tank; 4 - flow regulating valve; 5 - flowmeter; 6 - feed pump; 7 - oil-water separator; 8 - water production tank; 9 - oil collection tank. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as 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 the first aspect of the present invention, a surface-modified web is provided, the surface-modified web has a three-dimensional network structure, and the material of the surface-modified web is polypropylene associated with a surfactant on the surface;

[0028] Among them, the grammage of the surface-modified web is not less than 100 g / m 2 , the thickness is not less than 25 mm, and the porosity is greater than 50% by volume.

[0029] For example, the grammage of the web can be 150 - 650 g / m 2 (e.g., it can be 150 g / m 2 , 200 g / m 2 , 300 g / m 2 , 400 g / m 2 , 500 g / m 2 , 600 g / m 2 , 650 g / m 2 and values within the range formed by any two of the above values), the thickness can be 25 - 80 mm (e.g., it can be 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm and values within the range formed by any two of the above values), and the porosity can be 60 - 85 vol% (e.g., it can be 60 vol%, 65 vol%, 70 vol%, 75 vol%, 80 vol%, 82 vol%, 85 vol%). Applying the surface - modified web surface to oil - water separation can obtain a high oil - water separation efficiency, that is, it can achieve a high oil removal rate.

[0030] According to the present invention, in order to further improve the oil removal rate of the surface - modified web, preferably, the grammage of the surface - modified web is 200 - 500 g / m 2 , the thickness is 30 - 60 mm, and the porosity is 65 - 82 vol%.

[0031] According to the present invention, in order to further improve the surface - modification effect, make the surface - modified web have a higher oil removal rate, and further ensure long - term effectiveness, preferably, by weight, in the surface - modified web, the content ratio of polypropylene and surfactant is 100:1 - 30.

[0032] According to the present invention, in order to further improve the oil removal rate of the surface - modified web, 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 - 1000 g / 10 min, more preferably 400 - 800 g / 10 min. The inventors of the present invention found in the research that polypropylene within this melt - index range has good fluidity, processability, and the mechanical properties of the prepared surface - modified web are good. It can obtain a good modification effect without significantly affecting the polypropylene matrix material, making the oil removal rate of the prepared surface - modified web higher.

[0033] According to the present invention, in order to further improve the oil removal rate of the surface-modified mesh and further ensure long-term effectiveness, preferably, the molecular weight of the surfactant is 100-1000 g / mol (for example, it can be any value within the range formed by any two values among 100 g / mol, 200 g / mol, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol, 1000 g / mol and above).

[0034] According to the present invention, in order to further improve the oil removal rate of the surface-modified mesh and further ensure long-term effectiveness, preferably, the surfactant is selected from at least one of hydrocarbon surfactants and fluorocarbon surfactants. It can be understood that the fluorocarbon surfactant refers to a surfactant obtained by completely or partially replacing the hydrogen atoms in the hydrocarbon chain of the hydrocarbon surfactant with fluorine atoms, that is, a surfactant obtained by replacing the hydrocarbon chain with a fluorocarbon chain in the molecular structure. The non-polar group in the fluorocarbon surfactant has the property of being oil-repellent. The surface-modified mesh modified by such a surfactant has enhanced hydrophilic and oil-repellent properties, that is, enhanced selective retention ability and oil removal rate.

[0035] It can be understood that the surfactant described above has a relatively low molecular weight, is not easily volatile, and has good hydrophilicity. The surface-modified mesh prepared by using the surfactant and polypropylene described above can improve the oil removal rate while further ensuring long-term effectiveness.

[0036] According to the present invention, in order to further improve the oil removal rate of the surface-modified mesh and further ensure long-term effectiveness, preferably, the hydrocarbon surfactant is selected from at least one of sodium diisobutyl sulfosuccinate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium diisooctyl sulfosuccinate.

[0037] According to the present invention, in order to further improve the oil removal rate of the surface-modified mesh and further ensure long-term effectiveness, preferably, the fluorocarbon surfactant is selected from at least one of dodecafluorocarbon alkyl succinate sulfonate, potassium perfluorobutanesulfonate, and tetraethylammonium perfluorooctanesulfonate. The above fluorocarbon surfactants are relatively inexpensive. When the fluorocarbon surfactant and the hydrocarbon surfactant are used in combination, the oil removal rate can be improved while reducing the production cost.

[0038] According to the present invention, in order to further ensure that the surface-modified mesh can maintain long-term effectiveness, preferably, the surface-modified mesh also contains an antioxidant.

[0039] According to the present invention, in order to further ensure that the surface-modified web can remain effective for a long time, preferably, the antioxidant is selected from at least one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (which can be commercially available antioxidant 1010), triphenyl phosphite tris(2,4-di-tert-butyl) (which can be commercially available antioxidant 168), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (which can be commercially available antioxidant 1076), and 2,6-di-tert-butyl-4-methylphenol (which can be commercially available antioxidant 264).

[0040] According to the present invention, preferably, by weight, the content ratio of the polypropylene and the antioxidant is 9-99:1.

[0041] In a second aspect, the present invention provides a method for preparing a surface-modified web, the method comprising:

[0042] (1) Melting polypropylene and an optional antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers;

[0043] (2) Immersing the polypropylene fibers in a surfactant solution for surface modification to obtain surface-modified polypropylene fibers;

[0044] (3) Conducting a web-forming treatment on the surface-modified polypropylene fibers to obtain a surface-modified web having a three-dimensional network structure.

[0045] According to the present invention, in order to further improve the oil removal rate of the surface-modified web, preferably, 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 100-1000 g / 10 min, preferably 400-800 g / 10 min.

[0046] According to the present invention, in order to further ensure that the surface-modified web can remain effective for a long time, preferably, the antioxidant is selected from at least one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (which can be commercially available antioxidant 1010), triphenyl phosphite tris(2,4-di-tert-butyl) (which can be commercially available antioxidant 168), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (which can be commercially available antioxidant 1076), and 2,6-di-tert-butyl-4-methylphenol (which can be commercially available antioxidant 264).

[0047] According to the present invention, in order to further ensure that the surface-modified web can remain effective for a long time, preferably, by weight, the dosage ratio of the polypropylene and the antioxidant is 9-99:1.

[0048] According to the present invention, preferably, the temperature of the melting is 175 - 200 °C (for example, it can be 175 °C, 180 °C, 185 °C, 190 °C, 195 °C, 200 °C). It can be understood that the time of the melting is not particularly limited as long as it can ensure that the polypropylene and the optional antioxidant can be melted as much as possible.

[0049] According to the present invention, in order to make the spinning solution more uniform and enable the prepared surface-modified web to have a higher oil removal rate, preferably, the method further includes: stirring and degassing after melting.

[0050] According to the present invention, preferably, the conditions of the stirring include: stirring for 1 - 4 h in an inert gas atmosphere. The specific composition of the inert gas is not particularly limited, for example, it can be a gas such as nitrogen that does not react with the melted material.

[0051] According to the present invention, preferably, the conditions of the degassing include: the temperature is 175 - 200 °C, and standing for 0.5 - 2 h for degassing. The degassing temperature can be the same as the melting temperature.

[0052] According to the present invention, preferably, before spinning, the method further includes: performing solid-liquid separation on the spinning solution. It can be understood that through solid-liquid separation, the unmelted solid phase can be removed from the spinning solution. Among them, the specific method of the solid-liquid separation is not particularly limited, and filtration is preferred.

[0053] According to the present invention, preferably, the spinning method further includes: extruding, spinning, stretching, and cooling the spinning solution in sequence.

[0054] According to the present invention, in order to further improve the oil removal rate of the surface-modified web, preferably, the spinning conditions make the diameter of the polypropylene fiber 10 - 40 μm (for example, it can be any value within the range formed by any two values among 10 μm, 20 μm, 30 μm, 40 μm and above).

[0055] According to the present invention, preferably, the conditions of the extrusion include: the temperature is 145 - 180 °C (for example, it can be 145 °C, 150 °C, 160 °C, 170 °C, 180 °C). Among them, the extrusion device is not particularly limited, and it is preferably extruded through a pipeline into a screw extruder. For example, the spinning solution is input into the screw extruder through a pipeline and extruded, where the pipeline temperature, i.e., the extrusion temperature, is 145 - 180 °C.

[0056] According to the present invention, preferably, the conditions of the spinning include: the aperture of the spinneret is 0.1 - 2 mm, and the spinning temperature is 100 - 150 °C.

[0057] According to the present invention, preferably, the conditions for stretching include: using air current stretching, the temperature of the air current being 120 - 150 °C, and the spinning speed for stretching being 100 - 400 m / min. It can be understood that the spinning speed refers to the speed at which fibers are formed during the air current stretching process.

[0058] According to the present invention, preferably, the conditions for cooling include: using air cooling, the air temperature being 5 - 20 °C.

[0059] According to the present invention, in order to further improve the surface modification effect, preferably, before surface modification, the method further includes: washing and drying the polypropylene fibers in sequence. It can be understood that the washing is to remove the impurities attached to the polypropylene fibers, and the drying is to remove the moisture adsorbed by the polypropylene fibers after washing. More preferably, the washing method is to soak in ethanol for more than 12 hours first, and then wash with deionized water at least 3 times. More preferably, the drying is carried out at 65 - 75 °C for more than 24 hours.

[0060] According to the present invention, in order to further improve the surface modification effect, so that the surface modified mesh has a higher oil removal rate and further ensure long-term effectiveness, preferably, in step (2), the molecular weight of the surfactant is 100 - 1000 g / mol.

[0061] According to the present invention, in order to further improve the surface modification effect, so that the surface modified mesh has a higher oil removal rate and further ensure long-term effectiveness, preferably, the surfactant is selected from at least one of hydrocarbon surfactants and fluorocarbon surfactants.

[0062] According to the present invention, in order to further improve the surface modification effect, so that the surface modified mesh has a higher oil removal rate and further ensure long-term effectiveness, preferably, the hydrocarbon surfactant is selected from at least one of sodium diisobutyl sulfosuccinate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium diisooctyl sulfosuccinate.

[0063] According to the present invention, in order to further improve the surface modification effect, so that the surface modified mesh has a higher oil removal rate and further ensure long-term effectiveness, preferably, the fluorocarbon surfactant is selected from at least one of dodecafluorooctyl sulfosuccinate, potassium perfluorobutanesulfonate, and tetraethylammonium perfluorooctanesulfonate.

[0064] According to the present invention, in order to further improve the surface modification effect, so that the surface-modified web has a higher oil removal rate and further ensure long-term effectiveness, preferably, the mass ratio of the polypropylene fiber to the surfactant in the surfactant solution is 100:0.4 - 50. It can be understood that when the surfactant is within the above range, a better surface modification effect can be obtained while making full use of the materials.

[0065] It can be understood that after the polypropylene fiber is impregnated in the low-molecular-weight non-volatile surfactant solution, the surfactant will adsorb and desorb on the surface of the polypropylene fiber until the adsorption-desorption equilibrium is reached, and the adsorption amount reaches the maximum. Generally, when the adsorption amount is larger, a better modification effect can be obtained, and the surface-modified web has a higher oil removal rate.

[0066] According to the present invention, the conditions such as the temperature and time of the surface modification are not particularly limited, as long as the adsorption-desorption of the surfactant on the surface of the polypropylene fiber can reach equilibrium as soon as possible to obtain the maximum adsorption amount. Preferably, the conditions for the surface modification include: the time is 20 - 60 min (for example, it can be 20 min, 30 min, 40 min, 50 min, 60 min), and the temperature is 20 - 80 °C (for example, it can be 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C).

[0067] According to the present invention, preferably, before the web-forming treatment, the method further includes: drying the surface-modified polypropylene fiber. The specific method of the drying is not particularly limited. Preferably, the drying method is to dry for more than 12 hours under the condition of 55 - 65 °C.

[0068] According to the present invention, in order to further improve the oil removal rate of the surface-modified web, preferably, the method of the web-forming treatment includes: carding into a web, needling, and heat-sealing reinforcement in sequence. It can be understood that

[0069] The carding into a web means using a carding machine to card the fibers to make them arranged neatly and formed; the needling means using a needling machine to needle the formed fibers to make the fibers interweave and bond with each other to form a web; the heat-sealing reinforcement means using a hot melt bonding machine to further fix the fibers to form a web.

[0070] According to the present invention, in order to further improve the oil removal rate of the surface-modified web, preferably, the conditions of the web-forming treatment make the grammage of the surface-modified web not less than 100 g / m 2 , the thickness is not less than 25 mm, and the porosity is greater than 50% by volume; more preferably, the conditions of the web-forming treatment make the grammage of the surface-modified web be 200 - 500 g / m 2, with a thickness of 30 - 60 mm and a porosity of 65 - 82% by volume.

[0071] In a third aspect, the present invention provides a surface - modified mesh membrane prepared by the method as described above.

[0072] In a fourth aspect, the present invention provides the application of the surface - modified mesh membrane provided in the first aspect and the third aspect in treating oily sewage.

[0073] In a fifth aspect, the present invention provides a device for treating oily sewage. According to the flow direction of the material, the treatment device sequentially includes: a liquid storage tank and an oil - water separator;

[0074] Wherein, the liquid storage tank is used for storing oily sewage; the oil - water separator is filled with the surface - modified mesh membrane provided in the first aspect or the third aspect of the present invention for oil - water separation;

[0075] Wherein, the oil - water separator is also respectively connected to a water production tank and an oil collection tank. The water production tank is used for receiving the water phase from the oil - water separator, and the oil collection tank is used for receiving the oil phase from the oil - water separator.

[0076] According to the present invention, preferably, the device for treating oily sewage further includes a sewage tank located between the liquid storage tank and the oil - water separator. The sewage tank is used for receiving the oily sewage from the liquid storage tank and transporting it to the oil - water separator. Wherein, the sewage tank is provided with a sewage tank inlet and a sewage tank outlet; wherein, the sewage tank inlet is communicated with the liquid storage tank through a pipeline, and the sewage tank outlet is communicated with the oil - water separator through a pipeline.

[0077] According to the present invention, preferably, the device for treating oily sewage further includes a sewage pump on the pipeline between the liquid storage tank and the sewage tank, which is used for pumping the sewage in the liquid storage tank into the sewage tank.

[0078] According to the present invention, preferably, according to the material flow direction, the device for treating oily sewage further includes a flow regulating valve, a flow meter and a feed pump sequentially arranged on the pipeline between the sewage tank and the oil - water separator.

[0079] According to the present invention, preferably, the oil - water separator is provided with a sewage inlet, a water phase outlet and an oil phase outlet. The sewage inlet is located at the upper part of the oil - water separator. Wherein, the sewage inlet is used for introducing the oily sewage from the liquid storage tank into the oil - water separator, the water phase outlet is used for leading out the water phase obtained after separation by the surface - modified mesh membrane from the oil - water separator and introducing it into the water production tank, and the oil phase outlet is used for leading out the oil phase obtained after separation by the surface - modified mesh membrane from the oil - water separator and introducing it into the oil collection tank.

[0080] It is understandable that when separating the oily sewage through the oil-water separator, the surface-modified mesh filled therein has the function of being hydrophilic and oleophobic. Under the combined action of selective retention and coalescence separation, the water phase will pass through the surface-modified mesh and enter the lower part of the oil-water separator, while the oil phase will be retained and remain at the top 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.

[0081] According to the present invention, preferably, the water production tank is connected to the water phase outlet of the oil-water separator through a pipeline, and the oil collection tank is connected to the oil phase outlet of the oil-water separator through a pipeline.

[0082] In a sixth aspect, the present invention provides a method for treating oily sewage, which is carried out in the device as described above. The method includes: introducing the oily sewage in the liquid storage tank into the oil-water separator for oil-water separation.

[0083] According to the present invention, preferably, in the oil-water separator, the ratio of the filling volume of the surface-modified mesh to the volume of the oil-water separator is 1:2-4.

[0084] According to the present invention, preferably, in the oil-water separator, relative to the surface-modified mesh with a filling volume of 300L, the inlet rate of the oily sewage is 0.1-0.5m 3 / h.

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

[0086] Among them, the filling volume can be the volume of the mesh filled under the conventional filling operation in the art. For example, it can be the volume of the mesh filled into the bed layer of the oil-water separator by layered compaction under 0.2MPa.

[0087] According to a particularly preferred embodiment of the present invention, the preparation of the surface-modified mesh and the treatment of the oily sewage are carried out according to the following method:

[0088] (1) Take polypropylene with a melt index of 450-550 g / 10 min and antioxidant 1010 and add them to a spinning kettle with a stirring device for mixing. Among them, by weight, the dosage ratio of polypropylene to antioxidant 1010 is 20-26:1; carry out melting at 183-187°C, then stir for 1.8-2.2 h under a nitrogen atmosphere, stop stirring and stand for degassing at 183-187°C for 1.3-1.6 h to obtain a spinning solution;

[0089] After filtering the spinning solution through a filter screen, it is fed into a screw extruder through a pipeline and extruded under the condition that the extrusion temperature is 168 - 173 °C; then it is spun through the spinneret of the spinning pack by a metering pump. The aperture of the spinneret is 0.3 - 0.8 mm and the temperature is 127 - 132 °C; then it forms primary fibers after being stretched by air flow. The temperature of the air flow is 138 - 142 °C and the spinning speed is 260 - 290 m / min; then the primary fibers are cooled by cooling air. The temperature of the cooling air is 9 - 11 °C, and polypropylene fibers are obtained.

[0090] The polypropylene fibers are soaked in ethanol for more than 12 hours, then washed 3 times with deionized water to remove the impurities adsorbed on the surface of the polypropylene fibers, and then placed in an oven for drying to remove the moisture adsorbed on the surface.

[0091] The dried polypropylene fibers are immersed in a surfactant solution for surface modification to obtain surface-modified polypropylene fibers. In the surfactant solution, the surfactant is dodecafluorocarbon alkyl succinate sulfonate and sodium dodecyl sulfate. The mass ratio of the polypropylene fibers to the surfactant is 100:11 - 18; the temperature of surface modification is 48 - 54 °C and the time of surface modification is 28 - 33 min.

[0092] Then the surface-modified polypropylene fibers are dried at 55 - 65 °C for more than 12 hours. The dried surface-modified polypropylene fibers are taken, carded into a web, needled, and heat-sealed and reinforced to obtain a surface-modified web with a three-dimensional network structure.

[0093] (2) The surface-modified web is layered and compacted and filled into the bed layer of the oil-water separator. The filling volume of the surface-modified web and the volume of the oil-water separator are in a ratio of 1:2.5 - 3.5;

[0094] (3) The oily sewage with a temperature of 40 - 60 °C in the storage tank is pumped into the sewage tank by a sewage pump;

[0095] (4) Open the flow regulating valve and the flow meter, and pump the liquid in the sewage tank into the oil-water separator through a feed pump. By adjusting the flow regulating valve, control the inlet water flow within 0.1 - 0.2 m 3 / h for the treatment of oily sewage. The separated oil phase enters the oil collecting tank through the oil phase outlet, and the water phase from which the oil phase has been removed enters the produced water tank through the water phase outlet.

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

[0097] Antioxidant 1010, the component is pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0098] Antioxidant 168, with the component of tris(2,4-di-tert-butyl)phenyl phosphite;

[0099] Antioxidant 1076, with the component of n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

[0100] Antioxidant 264, with the component of 2,6-di-tert-butyl-4-methylphenol;

[0101] Sodium dodecyl sulfate, with a molecular weight of 288.38 g / mol;

[0102] Sodium diisobutyl sulfosuccinate, with a molecular weight of 332.35 g / mol;

[0103] Sodium diisooctyl sulfosuccinate, with a molecular weight of 445.57 g / mol;

[0104] Sodium dodecylbenzenesulfonate, with a molecular weight of 348.48 g / mol;

[0105] Perfluorocarbon alkyl sulfosuccinate, with a molecular weight of 556.19 g / mol;

[0106] Potassium perfluorobutanesulfonate, with a molecular weight of 338.2 g / mol;

[0107] Tetraethylammonium perfluorooctanesulfonate, with a molecular weight of 629.37 g / mol;

[0108] The determination of the melt index of polypropylene is carried out by the method of ASTM D1238-13 at a temperature of 230 °C and a load weight of 2.16 kg.

[0109] The test method for the grammage is as follows: First, take a sample with a grammage tester, then weigh it with a balance, and divide the obtained gram number by the area to get the grammage (g / m 2 ).

[0110] The porosity is measured by the mercury intrusion method using an Autopore IV-9500 fully automatic mercury intrusion porosimeter.

[0111] The tensile strength is tested by a 3342 universal material testing machine of INSTRON Company, USA. The total length of the specimen is 40 mm, the test temperature is 25 °C, and the loading speed is 40 mm / min.

[0112] The oil content in the oily sewage is determined according to the national standard "GB / T 16488-1996 Determination of Petroleum and Animal and Vegetable Oils in Water Quality".

[0113] The calculation method of the oil removal rate is:

[0114] Among them, C0 represents the oil content of the oily sewage in the sewage tank, with the unit of mg / L;

[0115] C represents the oil content of the water phase in the water production tank, with the unit of mg / L.

[0116] And, unless otherwise specified, the materials are all commercially available.

[0117] As Figure 1 shown, the treatment device for oily sewage of the present invention, according to the flow direction of the materials, successively includes a liquid storage tank 1, a sewage pump 2, a sewage tank 3, a flow regulating valve 4, a flowmeter 5, a feed pump 6, an oil-water separator 7, a water production tank 8 and an oil collection tank 9. Among them, the liquid storage tank 1 is used for storing oily sewage, the sewage temperature therein is 40 - 60 °C, and it is connected to the sewage pump 2 through a pipeline; the sewage pump 2 is connected to the sewage tank inlet of the sewage tank 3 through a pipeline, and is used for pumping the oily sewage in the liquid storage tank 1 into the sewage tank 3. The sewage tank outlet of the sewage tank 3 is connected to the feed pump 6 through a pipeline, and a flow regulating valve 4 and a flowmeter 5 are successively arranged on this pipeline. The feed pump is connected to the sewage inlet of the oil-water separator 7 through a pipeline, and is used for pumping the sewage in the sewage tank 3 into the oil-water separator 7 for treatment. The oil-water separator 7 is filled with a surface-modified mesh membrane to treat the oily sewage, that is, to separate the oil phase and 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 collection tank 9 through a pipeline, and the water phase outlet is connected to the water production tank 8 through a pipeline.

[0118] Examples 1 - 10 and Comparative Examples 1 - 2

[0119] (1) Take polypropylene and antioxidant and add them to a spinning kettle with a stirring device for mixing, and conduct melting. Then, stir for a period of time under the condition of passing nitrogen, stop stirring and stand for degassing to obtain a spinning solution;

[0120] After filtering the spinning solution through a filter screen, input it into a screw extruder through a pipeline for extrusion, and then spray it through the spinneret of the spinning component by a metering pump. Then, form a primary fiber after air stretching, and cool the primary fiber with cooling air to obtain polypropylene fibers with uniform thickness.

[0121] (3) Immerse the polypropylene fibers in ethanol for more than 12 hours, then wash them 3 times with deionized water to remove the impurities adsorbed on the surface of the polypropylene fibers. Then, place them in an oven at 70 °C for drying for more than 24 hours to remove the water adsorbed on the surface. Immerse the dried polypropylene fibers in a surfactant solution for surface modification to obtain surface-modified polypropylene fibers, and then dry them at 60 °C for 12 hours; weigh the dried surface-modified polypropylene fibers, and prepare a selective retention mesh membrane with a certain gram weight after carding into a web, needling and heat-sealing reinforcement.

[0122] The condition parameters of each step, the parameters of each material, as well as the gram weight, thickness, and porosity of the mesh for Examples 1-10 and Comparative Examples 1-2 are shown in Tables 1-3.

[0123] Table 1

[0124]

[0125]

[0126] Table 2

[0127]

[0128]

[0129] Table 3

[0130] Example Porosity (volume %) <![CDATA[Web grammage (g / m 2 )]]> Retinal thickness (mm) 1 65 500 40 2 82 200 50 3 70 430 30 4 79 260 50 5 77 320 40 6 76 380 60 7 73 400 40 8 71 420 50 9 85 150 25 10 60 650 80 Comparative Example 1 77 320 40 Comparative Example 2 - (Non-reticular) -

[0131] Among them, Comparative Example 1 was carried out according to the method of Example 5. The difference is that the polypropylene fibers were not immersed in the surfactant solution, that is, no surface modification was carried out, and the polypropylene fibers obtained by spinning were directly subjected to web-forming treatment; Comparative Example 2 was carried out according to the method of Example 5. The difference is that the surface-modified polypropylene fibers obtained after surface modification were not subjected to web-forming treatment. m(polypropylene resin: antioxidant) refers to the dosage ratio of the polypropylene and the antioxidant by weight.

[0132] Test Example

[0133] The modified meshes prepared in Examples 1-10 and Comparative Examples 1-2 were taken, and their tensile strengths were measured respectively. The results are shown in Table 4.

[0134] The oily wastewater from a certain refinery was taken. After measurement, the pH of the wastewater was 7.5 and the oil content was 7386 mg / L.

[0135] The surface-modified meshes prepared in Examples 1-10 and Comparative Examples 1-2, which had been used for more than 5 months before this test, were respectively used for treating oily sewage in the oily sewage treatment device as shown in Figure 1 shown.

[0136] The specific method is as follows:

[0137] (1) The products prepared in Examples 1-10 and Comparative Examples 1-2 were respectively packed into the bed layer of the oil-water separator in a stratified and compacted manner.

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

[0139] (3) Open the flow regulating valve and the flowmeter, and pump the liquid in the sewage tank into the oil-water separator via the feed pump. By adjusting the flow regulating valve, control is such that, relative to the packing volume of 300 L of the modified mesh, the inlet speed of the oily sewage is 0.1 - 0.5 m 3 / h.

[0140] After stable operation, take the water in the water production tank, measure the oil content therein, and calculate the oil removal rate. The results are shown in Table 4. Among them, the packing ratio is the ratio of the packing volume of the surface-modified mesh to the volume of the oil-water separator, and the inlet speed is the inlet speed relative to the surface-modified mesh with a packing volume of 300 L.

[0141] Table 4

[0142]

[0143]

[0144] It can be seen from the above results that the mesh prepared by adopting the technical solution of the present invention can still obtain a relatively high oil removal rate during oil-water separation after running for 5 months. It can be seen that the mesh prepared by the technical solution of the present invention can maintain a high-efficiency oil removal function for a long time. Comparative Examples 1 - 2 do not adopt the technical solution of the present invention, and the effects are poor. Moreover, compared with the product of Comparative Example 1 without modification, the meshes prepared in Examples 1 - 10 have a higher tensile strength, that is, modification by the method of the present invention will not reduce the physical strength of the bulk polypropylene fiber.

[0145] In addition, when preparing the mesh by adopting the technical solution of the present invention, the preparation is simple and suitable for industrial promotion. And if the oil removal function of the mesh decreases after a long time of use, the mesh can be washed and then the above impregnation / drying method can be used again to restore its function, and the operation is also relatively simple. Moreover, when using the technical solution of the present invention for oil-water separation, the energy consumption is low, no waste residue is generated, no secondary pollution is caused, the treatment process is safe and explosion-proof, the separation speed is fast, the flux is relatively high, and water conduction and oil interception can be achieved with low energy consumption relying on the action of liquid column static pressure, etc.

[0146] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a surface-modified mesh, characterized in that, The method includes: (1) Melting polypropylene and an antioxidant to obtain a spinning solution, and spinning the spinning solution to obtain polypropylene fibers; (2) Immersing the polypropylene fibers in a surfactant solution for surface modification to obtain surface-modified polypropylene fibers; (3) Conducting a web-forming treatment on the surface-modified polypropylene fibers to obtain a surface-modified web with a three-dimensional network structure; Among them, in step (1), according to the ASTM D1238-13 method, the melt index of the polypropylene is 400-800 g / 10 min at a temperature of 230 °C and a load weight of 2.16 kg; Among them, the conditions for the web-forming treatment are such that the basis weight of the surface-modified web is not less than 100 g / m 2 , the thickness is not less than 25 mm, and the porosity is greater than 50% by volume; Among them, by weight, the dosage ratio of the polypropylene and the antioxidant is 9-99:1; Among them, in step (2), the molecular weight of the surfactant is 100-1000 g / mol; Among them, the surfactant is selected from at least one of hydrocarbon surfactants and fluorocarbon surfactants.

2. The method according to claim 1, wherein The antioxidant is selected from at least one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris((2,4-di-tert-butyl)phenyl phosphite), n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,6-di-tert-butyl-4-methylphenol.

3. The method according to claim 1, wherein, The temperature of the melting is 175-200 °C.

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

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

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

7. The method according to claim 1, wherein The hydrocarbon surfactant is selected from at least one of sodium diisobutyl sulfosuccinate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium diisooctyl sulfosuccinate.

8. The method according to claim 1, wherein, The fluorocarbon surfactant is selected from at least one of dodecafluorocarbon alkyl succinate sulfonate, potassium perfluorobutanesulfonate, and tetraethylammonium perfluorooctanesulfonate.

9. The method according to claim 1, wherein The mass ratio of the polypropylene fibers to the surfactant in the surfactant solution is 100:0.4-50; And / or, the surface modification conditions include: a time of 20-60 min and a temperature of 20-80 °C.

10. The method according to claim 1, wherein, The web-forming treatment method includes: sequentially carding into a web, needling, and thermally bonding for reinforcement.

11. The method according to claim 1, wherein, The conditions of the web-forming treatment result in the basis weight of the surface-modified web being 200 - 500 g / m 2 , the thickness being 30 - 60 mm, and the porosity being 65 - 82 vol%.

12. A surface-modified web prepared by the method according to any one of claims 1-11.

13. Use of the surface-modified web according to claim 12 in treating oily sewage.

14. A treatment device for oily sewage, according to the flow direction of the material, the treatment device successively includes: A liquid storage tank and an oil-water separator; Among them, the liquid storage tank is used to store oily sewage; the oil-water separator is filled with the surface-modified web according to claim 12 for oil-water separation; Among them, the oil-water separator is further connected to a water production tank and an oil collection tank respectively. The water production tank is used to receive the aqueous phase from the oil-water separator, and the oil collection tank is used to receive the oil phase from the oil-water separator.

15. A method for treating oily sewage, characterized in that, The method is carried out in the device according to claim 14, and the method includes: introducing the oily sewage in the liquid storage tank into the oil-water separator for oil-water separation.

16. The method according to claim 15, wherein, In the oil-water separator, the filling volume ratio of the surface-modified web to the volume of the oil-water separator is 1:2-4.

17. The method according to claim 15, wherein In the oil-water separator, with respect to the surface-modified mesh with a filling volume of 300 L, the inlet speed of the oily sewage is 0.1 - 0.5 m 3 / h.

18. The method according to claim 15, wherein, The temperature of the oily sewage is 40 - 60 °C.

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