Preparation method of electrically-controlled anti-pollution decontamination oil-water separation stainless steel mesh

Abstract

The invention relates to a preparation method of an oil-water separation stainless steel mesh capable of resisting and removing dirt through electric control, and belongs to the technical field of new materials. The preparation method comprises the following steps: firstly, assembling a layer of carbon nanotubes on the surface of the stainless steel mesh through a vacuum self-assembly technology, then quickly dip-coating a poly (styrene-co-maleic anhydride) cross-linking agent, dip-coating polyethyleneimine to generate a cross-linked copolymer coating, and finally preparing the super-hydrophilic / underwater super-oleophobic stainless steel mesh. After the stainless steel mesh is used as a cathode, pollution can be slowed down by using electrostatic repulsive force between polarized charges and pollutants, and surface polluted components can be stripped and removed. The separation flux of the stainless steel mesh to the oil-water emulsion reaches 1200 liters per square meter per hour, the separated water can reach the national sewage discharge standard, the anti-pollution and decontamination performance of the stainless steel mesh is greatly improved under the electrostatic repulsion action of polarized charges, and long-acting separation of various oil-water emulsions can be achieved.

Description

Technical Field

[0001] The invention relates to an oil-water separation material, in particular to a method for preparing an electrically controlled anti-fouling and decontamination oil-water separation stainless steel net, belonging to the technical field of new materials. Background Art

[0002] With the rapid development of modern industrialization, a large amount of oily wastewater is discharged into freshwater, which seriously endangers the marine ecosystem and even human health. The waste oil in the water usually exists in the form of suspension and emulsification. The suspended oil and water exist independently of each other, and can usually be effectively separated by gravity. The emulsified oil is stably dispersed in the water in the form of tiny droplets, which is difficult to treat. At present, the traditional oil-water emulsion treatment technologies mainly include centrifugation, flocculation, and flotation. However, these methods generally have obvious shortcomings, such as low separation accuracy and high energy consumption of centrifugation; flocculation will cause secondary pollution to the water body; flotation has a slow treatment rate and low accuracy. Moreover, in recent years, the discharge standard of oil content in sewage has been increased from 40mg / L to 5mg / L, which has put forward higher requirements for the treatment of oily emulsion wastewater. The traditional oil-water separation technology has gradually failed to meet the production and emission needs of the current industry. Therefore, new oil-water emulsion treatment technology is urgently needed.

[0003] In recent years, membrane separation technology has been considered to be the most promising technology in the field of oil-water emulsion treatment due to its advantages such as high separation accuracy, low energy consumption, recoverable concentrate and easy modular assembly. The core of membrane separation technology is membrane materials. Micro-nanostructure and chemical composition are two key factors affecting the wettability of membrane materials. Most commonly used hydrophilic chemical components contain polar groups such as hydroxyl and amino groups. These polar groups are protonated to make the membrane surface charged. This type of membrane material is called a charged membrane. The advantage of a charged membrane is that it uses the electrostatic repulsion between the surface charge of the membrane and the pollutants with the same charge to reduce membrane fouling; while the limitation is that it increases the adsorption of pollutants with opposite charges, causing the membrane material to lose its super wettability, which seriously affects the long-term separation performance of the membrane. Traditional strategies for treating membrane fouling include emulsion pretreatment, backwashing, chemical cleaning and photodegradation. Although these technologies have alleviated the problem of membrane fouling to a certain extent, they have disadvantages such as secondary pollution, shortened membrane service life, interrupted membrane separation process and increased operating costs. Combining electric field and membrane separation process to form an electrically controlled membrane is currently a hot research topic in the field of membrane material anti-fouling and anti-fouling. Conductive membranes are commonly used as cathodes. Conductive membranes exhibit antifouling and decontamination properties under the action of an external electric field. However, the free charges generated on the surface of the conductive membrane under the action of the electric field are in an unstable free state, which limits the application of conductive membranes. Under the action of an external electric field, the internal positive and negative charges of dielectric materials shift to generate polarized charges, which are bound charges that cannot move freely. Therefore, using these polarized charges to achieve the repulsion and stripping of pollutants on the membrane surface is a new research idea.

[0004] In order to solve the key problem that the surface of membrane materials is easily contaminated, resulting in low separation efficiency and difficulty in achieving long-term separation, the present invention prepares an electrically controlled anti-fouling and decontamination oil-water separation stainless steel mesh, which significantly improves the service life of the membrane material by utilizing the electrostatic repulsion effect of polarized charges, and can be used for the long-term separation of a variety of oil-water emulsions. Summary of the invention

[0005] The present invention specifically relates to a method for preparing an electrically controlled anti-fouling and decontamination oil-water separation stainless steel mesh. The stainless steel mesh prepared by the method significantly improves the service life in the oil-water separation process, effectively solves the current problems of easy contamination of separation membranes and reduced separation flux, and realizes long-term separation.

[0006] The implementation process of the present invention is briefly explained below. First, a layer of carbon nanotubes is assembled on the surface of a stainless steel mesh by a vacuum self-assembly method, and then a poly(styrene-co-maleic anhydride) crosslinking agent is quickly dip-coated, followed by a polyethyleneimine dip-coated crosslinked copolymer coating, and finally a super-hydrophilic / underwater super-oleophobic stainless steel mesh is prepared.

[0007] The present invention specifically relates to a method for preparing an electrically controlled anti-fouling and decontamination oil-water separation stainless steel mesh, which is achieved through the following specific steps:

[0008] (1) First, the stainless steel mesh is ultrasonically cleaned with acetone solution, ethanol solution, and deionized water for ten minutes in sequence, and then the stainless steel mesh is ultrasonically etched in a 0.5-1.5 mol / L hydrochloric acid solution for 10 minutes, and then placed in a 60°C oven to dry for 12 hours for use.

[0009] (2) 1-5 mg of carboxylic acid carbon nanotubes were ultrasonically dispersed in 50 ml of ethanol for 1 hour, and then the carboxylic acid carbon nanotube solution uniformly dispersed after ultrasonication was vacuum filtered onto a clean stainless steel mesh and placed in an oven at 60 degrees Celsius for drying.

[0010] (3) 1-3 g of poly(styrene-co-maleic anhydride) (PSMA) was dissolved in 100 ml of N,N-dimethylformamide (DMF) and magnetically stirred for 30 minutes, and then the dried stainless steel mesh was immersed in the PSMA solution for 5-20 seconds. It was then immersed in a 3-5wt% polyethyleneimine (PEI) solution for 20-40 minutes. Finally, the stainless steel mesh was suspended in a gradient temperature increase to dry the PEI into a film, that is, first dried in a 60 degree Celsius oven for 10-14 hours, and then dried in ovens at 100 degrees Celsius, 120 degrees Celsius and 150 degrees Celsius for 1-3 hours, and finally a super hydrophilic / underwater super oleophobic oil-water separation stainless steel mesh was obtained.

[0011] The method for preparing the oil-water separation stainless steel mesh provided by the present invention can realize the efficient and lasting separation of the oil-in-water emulsion, so as to realize large-scale promotion and application in the field of oily wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Attached Figure 1 This is a scanning electron microscope image of the stainless steel mesh prepared in the present invention.

[0013] Attached Figure 2 This is a picture of the contact angles of water droplets in the air and underwater lubricating oil on the surface of the stainless steel mesh prepared by the present invention.

[0014] Attached Figure 3 A diagram showing the separation effect of the stainless steel mesh prepared by the present invention on lubricating oil-in-water emulsion.

[0015] Attached Figure 4 The anti-fouling performance of the stainless steel mesh prepared by the present invention is compared with and without the action of polarized charges. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0017] Example 1, first the stainless steel mesh was ultrasonically cleaned with acetone solution, ethanol solution and deionized water for ten minutes, then the stainless steel mesh was ultrasonically etched in 1 mol per liter hydrochloric acid solution for 10 minutes, and then dried in a 60 degree Celsius oven for 12 hours. 4 mg of carboxylic acid carbon nanotubes (CNT) were ultrasonically dispersed in 50 ml of ethanol for 1 hour, and then the carboxyl carbon nanotube solution uniformly dispersed after ultrasound was vacuum filtered onto the cleaned stainless steel mesh, and placed in a 60 degree Celsius oven for drying. 2 grams of poly (styrene-co-maleic anhydride) (PSMA) was dissolved in 100 ml of N, N-dimethylformamide (DMF) and magnetically stirred for 30 minutes, and then the dried stainless steel mesh was immersed in the PSMA solution for 10 seconds. It was then immersed in a 4wt% polyethyleneimine (PEI) solution for 30 minutes. Finally, the stainless steel mesh was suspended and heated in a gradient manner to dry the PEI into a film, that is, it was first dried in an oven at 60 degrees Celsius for 12 hours, and then dried in ovens at 100 degrees Celsius, 120 degrees Celsius and 150 degrees Celsius for 2 hours, finally obtaining a super hydrophilic / underwater super oleophobic oil-water separation stainless steel mesh.

[0018] Attached Figure 1 The scanning electron microscope images of carbon nanotube / stainless steel mesh and carbon nanotube / stainless steel mesh modified by polyethyleneimine are shown in Figure 1. As can be seen from the figure, carbon nanotubes are evenly assembled on the surface of the stainless steel mesh, reducing the pore size. After cross-linking and dip-coating modification, a layer of cross-linked microspheres is evenly coated on the surface, significantly improving the surface roughness.

[0019] Attached Figure 2 This is an optical picture of the contact angles of water droplets in the air and underwater lubricating oil on the surface of the stainless steel mesh prepared in this experiment. As can be seen from the figure, the stainless steel mesh exhibits excellent superhydrophilicity and underwater superoleophobicity, with the contact angle of water droplets in the air being 0° and the contact angle of underwater lubricating oil reaching 160.4±1°.

[0020] Attached Figure 3 The figure shows the separation effect of the prepared stainless steel mesh on the water-in-lubricating oil emulsion. As can be seen from the figure, there are many oil droplets in the emulsion before separation, and there are almost no residual oil droplets after separation by the prepared stainless steel mesh, which proves that the stainless steel mesh has a good separation effect.

[0021] Attached Figure 4 The figure shows the anti-fouling performance comparison of the prepared stainless steel mesh with and without the electric field. As can be seen from the figure, the flux reduction coefficient (FDR) of the membrane increases significantly under the electric field, proving that the electrostatic repulsion of the polarized charges generated under the electric field significantly improves the anti-fouling performance of the membrane.

Claims

1. The present invention specifically relates to a method for preparing an electrically controlled anti-fouling and decontamination oil-water separation stainless steel mesh, which is specifically obtained by the following method: (1) First, the stainless steel mesh is ultrasonically cleaned with acetone solution, ethanol solution, and deionized water for ten minutes in sequence, and then the stainless steel mesh is ultrasonically etched in a 0.5-1.5 mol / L hydrochloric acid solution for 10 minutes, and then dried in an oven at 60 degrees Celsius for 12 hours for use. (2) 1-5 mg of carboxylic acid carbon nanotubes were ultrasonically dispersed in 50 ml of ethanol for 1 hour, and then the carboxylic acid carbon nanotube solution uniformly dispersed after ultrasonication was vacuum filtered onto a clean stainless steel mesh and placed in an oven at 60 degrees Celsius for drying. (3) 1-3 g of poly(styrene-co-maleic anhydride) (PSMA) was dissolved in 100 ml of N,N-dimethylformamide (DMF) and magnetically stirred for 30 minutes, and then the dried stainless steel mesh was immersed in the PSMA solution for 5-20 seconds. It was then immersed in a 3-5wt% polyethyleneimine (PEI) solution for 20-40 minutes. Finally, the stainless steel mesh was suspended in a gradient temperature increase to dry the PEI into a film, that is, first dried in a 60 degree Celsius oven for 10-14 hours, and then dried in ovens at 100 degrees Celsius, 120 degrees Celsius and 150 degrees Celsius for 1-3 hours, and finally a super hydrophilic / underwater super oleophobic oil-water separation stainless steel mesh was obtained.

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