Super-hydrophobic sponge material for high-efficiency separation of stratified and emulsified oil-water mixtures, and preparation method and application thereof

Abstract

The application discloses super-hydrophobic sponge material for high-efficiency separation of layered and emulsified oil-water mixture and a preparation method and application thereof. Metal oxide powder is added into a silane modifier, solid residues are filtered out after sufficient reaction under certain air humidity to obtain a target modified liquid, and the target modified liquid is used for hydrophobic modification of melamine sponge to obtain super-hydrophobic sponge blocks for high-efficiency separation of layered oil-water mixture; meanwhile, the waste sponge blocks are crushed and modified according to the same method to obtain super-hydrophobic sponge powder for high-efficiency separation of emulsified oil-water mixture. The super-hydrophobic sponge powder is used to realize continuous demulsification of crude oil salt water emulsion through a self-built instrument, and the feasibility of on-site application is proved. The application provides a new material for high-efficiency separation of layered and emulsified oil-water mixture, and provides a new strategy for reuse of waste sponge, and realizes the environmental protection concept of 'waste treatment with waste and waste into treasure'.

Description

Technical Field

[0001] This invention belongs to the field of functional materials and oil-water separation, and specifically relates to a method for preparing and applying a superhydrophobic sponge material. Background Technology

[0002] The continuous and vigorous development of industry inevitably produces large quantities of oil-water mixtures. If these industrial byproducts are not treated in a timely and effective manner, they will greatly affect the efficiency of enterprises and seriously pollute the environment. Oil-water mixtures can be broadly classified into layered oil-water mixtures and emulsion oil-water mixtures based on their appearance. The former is commonly found in oily wastewater discharged from industries and in frequent marine oil spills, where oil and water ultimately form two immiscible phases due to differences in density and polarity. Emulsion oil-water mixtures can be mainly divided into two categories based on the difference between the continuous phase and the dispersed phase: oil-in-water emulsions and water-in-oil emulsions. Statistics show that 90-95% of the world's crude oil production is produced in emulsion form, with water-in-oil emulsions being the most prevalent. Except during waterless oil recovery, water-bearing crude oil is violently disturbed when flowing through formation pores, pipelines, pumps, valves, or during sudden degassing, forming a homogeneous and stable emulsion under the action of natural surfactants and reservoir particles in the crude oil.

[0003] Traditional oil-water separation methods are mainly divided into physical, chemical, and biological methods. Physical methods such as gravity sedimentation, centrifugation, and electro-dehydration are energy-intensive and require large-scale equipment. Chemical demulsification has poor adaptability and can easily cause secondary pollution due to the toxicity and corrosiveness of the demulsifiers themselves. Biodegradation methods are costly and inefficient, and have not yet been widely used. Recently, a simple method for achieving efficient and rapid separation through material wettability has gradually come into focus. Inspired by this method, a large number of materials with different selectivity to oil and water have been developed and reported. For example, modified 2D / 3D materials such as polymer membranes, metal meshes, fabrics, nanomaterial microarrays, and porous sponges are widely used in oil-water separation. Three-dimensional porous sponges, in particular, have become a rising star in the industry due to their porosity, high specific surface area, and excellent oil storage capacity. Modifiers are typically chemical reagents that can improve the surface roughness and surface energy of the substrate.

[0004] However, the above materials can only be used alone to separate layered oil-water mixtures or emulsified oil-water compounds. There are few reports of materials that can be used for efficient separation of both at the same time. Moreover, the above emulsion separation experiments are mostly limited to ideal models, that is, using a single-component alkane or organic solvent as the oil phase, using deionized water as the water phase, adopting an extreme oil-water ratio, and not considering the influence of temperature and formation particles on the demulsification effect. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a superhydrophobic sponge material for the efficient separation of layered and emulsion oil-water mixtures, its preparation method, and its application. This invention aims to obtain a sponge material that can achieve efficient separation of both layered and emulsion oil-water mixtures, possessing stable superhydrophobic properties, excellent mechanical properties, and durability, thus realizing the green and environmentally friendly concept of "treating waste with waste and turning waste into treasure." Simultaneously, the sponge material can be used for the continuous and efficient demulsification of crude oil-in-salt emulsions containing quartz sand particles.

[0006] The method for preparing a superhydrophobic sponge material for efficient separation of layered and emulsion oil-water mixtures provided by this invention includes the following:

[0007] The modified porous sponge substrate was ultrasonically cleaned and dried with petroleum ether and ethanol, respectively. Metal oxide powder was added to silane modifier and reacted fully under certain air humidity. The target modified liquid was obtained by filtration. The cleaned and dried sponge was immersed in the obtained target modified liquid and then removed. The residual modified liquid was squeezed out and dried to obtain a superhydrophobic sponge block for efficient separation of layered oil-water mixtures.

[0008] The waste sponge block (such as the sponge block that has lost its mechanical properties and oil storage capacity after being repeatedly used to separate layered oil-water mixtures) is crushed, ultrasonically cleaned with petroleum ether and ethanol respectively and dried, and then modified with the same modification liquid in the same way to obtain superhydrophobic sponge powder for efficient separation of emulsion oil-water mixtures.

[0009] In the above method, the porous sponge is preferably a commercial sponge (melamine sponge) whose main component is a formaldehyde-melamine-sodium bisulfite copolymer.

[0010] In the above method, the metal oxide is preferably iron(III) oxide.

[0011] In the above method, the silane modifier is further described as a toluene solution of methyltrichlorosilane.

[0012] Preferably, the volume fraction of methyltrichlorosilane in the silane modifier is 0.1% to 3.0%; more preferably, the ratio of the metal oxide to the silane modifier is 2g of metal oxide powder added per 100mL of modifier.

[0013] In the above method, the metal oxide powder is further added to the silane modifier and the mixture is stirred gently for 25 to 35 minutes at an air humidity of 30% to 80%.

[0014] In the above method, the soaking time of the sponge in the modified liquid is 10-150 min, and the drying temperature is 85-95℃.

[0015] In the above method, a high-speed pulverizer is used to pulverize the waste sponge blocks. The pulverizer (FTT1000A) has a rated speed of about 32,000 rpm and a pulverizing time of 1 to 8 minutes.

[0016] In the above method, further, the amount of the modified liquid used is sufficient to fully wet the sponge.

[0017] This invention also provides superhydrophobic sponge blocks and superhydrophobic sponge powder materials prepared by the above method. The superhydrophobic sponge powder material can be directly reused by crushing and remodeling waste superhydrophobic block materials, thereby saving resources and being environmentally friendly.

[0018] This invention also provides the application of the above-mentioned superhydrophobic sponge material in the efficient separation of layered and emulsion oil-water mixtures. The application involves using bulk superhydrophobic sponge material for the separation of layered oil-water mixtures and powdered superhydrophobic sponge material for the separation of emulsion oil-water mixtures.

[0019] The present invention also provides the application of the above-mentioned powdered superhydrophobic sponge material in the demulsification of crude oil-in-salt emulsion in oilfields.

[0020] The mechanism of oil-water separation of the superhydrophobic sponge material described in this invention is as follows (wherein the chemical reaction mechanism is as follows). Figure 1 (As shown): The transformation of melamine sponge from hydrophilic to superhydrophobic is caused by a synergistic effect of three processes. First, silanization: Methyltrichlorosilane is a very reactive chemical reagent that reacts with trace amounts of water in the air to form silanols. These silanols further condense to form oligomers. When the melamine sponge is immersed in the modification solution, the free hydroxyl groups on the oligomers form hydrogen bonds with the secondary amines of the melamine sponge. Then, under high-temperature conditions (drying process), dehydration occurs, and covalent bonds are formed, completing the silanization of the melamine sponge. Second, the byproduct of methyltrichlorosilane hydrolysis, hydrogen chloride, reacts with iron(III) oxide, consuming the hydrogen chloride in the system while generating a large amount of Fe. 2+ Fe 3+ The ions were then completely oxidized to Fe during subsequent heating. 3+ The empty orbitals of these ions coordinate with the lone pairs of electrons on the N and O atoms of the sponge skeleton, further reducing the surface energy. Third, silanization also increases the surface roughness of the melamine sponge skeleton; according to the Wenzel model, this change in roughness also improves the material's wettability. Due to the special oil-water selectivity of superhydrophobic sponges, they can act as adsorbents to achieve efficient separation of layered oil-water mixtures by selectively absorbing the oil phase. Furthermore, due to the size effect and oil-water selectivity, the crushed superhydrophobic sponge powder can also act as a filter material, selectively allowing the oil phase to pass through while repelling the water phase, thus achieving efficient separation of emulsion-like oil-water mixtures.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The superhydrophobic sponge block prepared in this invention, as an adsorbent material, possesses stable superhydrophobic properties and excellent mechanical properties. It can be repeatedly used for the efficient separation of layered oil-water mixtures, with a separation efficiency approaching 100%. The superhydrophobic sponge powder prepared by breaking down and re-modifying waste or reused block sponges that have lost their mechanical properties in the separation of layered oil-water mixtures, can be used as a filter material for the efficient separation of emulsion oil-water mixtures, with a demulsification efficiency of 97.65%–99.33%. It can also achieve continuous demulsification of crude oil-containing brine emulsions containing quartz sand particles. This invention realizes the green material concept of "treating waste with waste and turning waste into treasure."

[0023] 2. The sponge prepared by this invention can achieve stable superhydrophobicity and has excellent mechanical properties and durability.

[0024] 3. The sponge material matrix of the present invention is melamine commercial sponge, which is lightweight, porous and inexpensive. The modifying reagent is widely available, inexpensive and used in small quantities. Moreover, the preparation method is simple, mild and energy-efficient, and suitable for industrial production.

[0025] 4. The application method provided by this invention takes into account the field working conditions, that is, when preparing simulated crude oil-salt emulsion, crude oil is used as the oil phase and salt water is used as the water phase, adopting a more suitable oil-water ratio, and taking into account the influence of temperature and reservoir particles, providing a theoretical basis and technical support for the practical application of superhydrophobic sponge materials, and has broad application prospects. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the superhydrophobic modification chemical mechanism of the present invention.

[0027] Figure 2 The images show actual contact angle diagrams of the samples prepared in Example 2 and Comparative Examples 1-3 (A shows the superhydrophobic properties and actual contact angle diagram of the sponge in Example 2, and B-D show actual contact angle diagrams of the sponges prepared in Comparative Examples 1-3, respectively).

[0028] Figure 3 The stress-strain curve of sample MS-0.5-30-30 prepared in Example 2 is shown.

[0029] Figure 4 The bar chart shows the oil absorption ratio of sample MS-0.5-30-30 prepared in Example 2.

[0030] Figure 5The following is a graph showing the durability test results of sample MS-0.5-30-30 prepared in Example 2 (A is a bar graph of the contact angle after 24 hours of extreme environmental treatment, and B is a graph of repeated oil absorption).

[0031] Figure 6 The image shows a comparison of scanning electron microscope (SEM) images of sample MS-0.5-30-30 prepared in Example 2 and an unmodified clean sponge block (A is the SEM image of the original sponge block, and B is the SEM image of the modified sponge block).

[0032] Figure 7 This is a comparison of the pore size distribution curves of sample MS-0.5-30-30 prepared in Example 2 and the unmodified clean sponge block.

[0033] Figure 8 The image shows a comparison of the infrared spectra of sample MS-0.5-30-30 prepared in Example 2 and an unmodified clean sponge block.

[0034] Figure 9 The X-ray photoelectron spectra of sample MS-0.5-30-30 prepared in Example 2 are compared with those of an unmodified clean sponge block (A is the full spectrum, B and C are the high-resolution fine spectra of O1s and N1s, respectively).

[0035] Figure 10 The images show a comparison of the separation performance of sample MS-0.5-30-30 prepared in Example 2 and unmodified clean sponge block in separating layered oil-water mixtures (A is a real photo of the modified sponge block separating layered n-dodecane-water mixture, B is a real photo of the original sponge block separating layered n-dodecane-water mixture, and C is a real photo of the modified sponge block separating layered chloroform-water mixture).

[0036] Figure 11 Figure 17 shows the results of the separation performance test of the superhydrophobic sponge powder prepared in Example 17 on an ideal water-in-oil emulsion model (A is a schematic diagram of the process, B is an optical microscope image of the emulsion before demulsification, with the inset showing the appearance of the emulsion, C is an optical microscope image of the filtrate after demulsification, with the inset showing the appearance of the filtrate, and D is a comparison of the demulsification flux and demulsification efficiency of the modified sponge powder on different emulsion models).

[0037] Figure 12 The figure shows the test results of the separation performance of the superhydrophobic sponge powder prepared in Example 17 on crude oil-in-salt emulsion (A is a schematic diagram of the self-made device, and B is a diagram of the demulsification mechanism). Detailed Implementation

[0038] The following detailed embodiments further illustrate the superhydrophobic sponge of the present invention, which can be used for efficient separation of layered and emulsion oil-water mixtures.

[0039] In the following examples, bulk melamine sponge blocks were purchased from Beijing Kelinmei High-Tech Materials Co., Ltd.; methyltrichlorosilane (98%) was purchased from Shanghai Titan Technology Co., Ltd.; toluene (99.5%) was purchased from Chengdu Kelong Chemical Co., Ltd.; ferric oxide (≥97%) and ferric chloride (98%) were purchased from Tianjin Fuchen Chemical Reagent Co., Ltd.; various oils and other organic solvents were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; crude oil, Span-80, mineralization information and 80-100 mesh quartz sand were provided by PetroChina Changqing Oilfield Branch; the deionized water used in the experiment was self-made by an ultrapure water system with a resistivity of 18.25 MΩ·cm.

[0040] Example 1

[0041] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.1% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting hydrophobic sponge block was designated MS-0.1-30-30.

[0042] Example 2

[0043] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-30.

[0044] Example 3

[0045] Methyltrichlorosilane was added to toluene to prepare 100 mL of silane modifier with a volume fraction of 1.0%. 2 g of iron oxide powder was added, and the mixture was stirred and reacted for 30 min at 30% air humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-1.0-30-30.

[0046] Example 4

[0047] Methyltrichlorosilane was added to toluene to prepare 100 mL of silane modifier with a volume fraction of 1.5%, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% air humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-1.5-30-30.

[0048] Example 5

[0049] Methyltrichlorosilane was added to toluene to prepare 100 mL of 2.0% silane modifier by pipette, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-2.0-30-30.

[0050] Example 6

[0051] Methyltrichlorosilane was added to toluene to prepare 100 mL of silane modifier with a volume fraction of 3.0%, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% air humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-3.0-30-30.

[0052] Example 7

[0053] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 40% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-40-30.

[0054] Example 8

[0055] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipette, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 50% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-50-30.

[0056] Example 9

[0057] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 60% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-60-30.

[0058] Example 10

[0059] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipette, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 70% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-70-30.

[0060] Example 11

[0061] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 80% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-80-30.

[0062] Example 12

[0063] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 10 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-10.

[0064] Example 13

[0065] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipette, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 60 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-60.

[0066] Example 14

[0067] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 90 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-90.

[0068] Example 15

[0069] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipetting, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 120 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-120.

[0070] Example 16

[0071] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier by pipette, and 2 g of iron oxide powder was added. The mixture was stirred and reacted for 30 min at 30% humidity. The solid was then filtered off to obtain the target modified solution. A clean melamine sponge block was immersed in the above target modified solution for 150 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was designated MS-0.5-30-150.

[0072] Comparative Example 1

[0073] At 30% air humidity, a clean melamine sponge block was immersed in 100 mL of toluene solvent for 30 min, then removed and the residual solvent was squeezed out. The sponge block was then dried in an oven at 90℃. The resulting sponge block was designated MS-TL.

[0074] Comparative Example 2

[0075] Prepare a 100 mL saturated ferric chloride toluene solution at 30% air humidity. Soak a clean melamine sponge in the above saturated solution for 30 min, then remove it and squeeze out the residual solution. Dry it in an oven at 90℃. The resulting hydrophobic sponge block is denoted as MS-FeCl3.

[0076] Comparative Example 3

[0077] Methyltrichlorosilane was added to toluene to prepare 100 mL of 0.5% silane modifier. After stirring and reacting for 30 min at 30% humidity, a clean melamine sponge block was immersed in the modified solution for 30 min, then removed and the residual modified solution was squeezed out. Finally, it was dried in an oven at 90℃. The resulting superhydrophobic sponge block was named MS-MTCS.

[0078] Example 17

[0079] Waste sponge blocks were placed in a high-speed pulverizer and pulverized for 4 minutes at the rated speed. Then, hydrophobic modification was carried out according to the steps described in Example 2 to obtain superhydrophobic sponge powder.

[0080] Example 18 Wettability Test

[0081] The wettability of the modified sponge blocks prepared in Examples 1-16 and Comparative Examples 1-3 was tested using a German DSA25 optical contact angle meter. Specifically, at room temperature and pressure, 8 μL of deionized water was injected at a time using a microsyringe, and the sample was moved upwards using the seated drop method to drop the droplet onto the sample surface. The droplet image was captured using a standard CCD camera, and the contact angle (WCA) of the sample was measured. Three different locations were measured for each sample, and the average value of the results was taken as the final contact angle of the sample to reduce error. It is generally considered that when WCA > 90°, the material is hydrophobic, and vice versa; furthermore, when WCA > 150°, the material is superhydrophobic.

[0082] The preparation conditions and wettability test results of Examples 1-16 are shown in Table 1. The test results show that, except for sample MS-0.1-30-30 prepared in Example 1, all samples prepared under the conditions described in the other examples achieved stable superhydrophobicity. However, with the increase of various variables, methyltrichlorosilane continued to hydrolyze and condense, forming a thicker polysiloxane film on the surface of the sponge skeleton, and even gradually detached from the skeleton, gradually blocking the sponge pores, increasing the sponge mass while reducing the sponge's porosity and oil storage space. Therefore, considering time and economic cost, contact angle, and mass gain ratio, sample MS-0.5-30-30 prepared under the conditions described in Example 2 showed the best performance, and its corresponding preparation conditions are the optimal preparation conditions. The superhydrophobic properties and actual contact angle of MS-0.5-30-30 are shown in the table below. Figure 2 As shown in Figure A.

[0083] Table 1.

[0084]

[0085]

[0086] The preparation conditions and wettability test results of Comparative Examples 1-3 are shown in Table 2. As can be seen from the table data, the sponge MS-TL treated with toluene solvent did not exhibit hydrophobicity. This is because toluene itself only acts as a solvent and cannot change the sponge's wettability. However, sponges MS-FeCl3 and MS-MTCS treated with saturated ferric chloride toluene solution and 0.5% (v / v) methyltrichlorosilane toluene solution showed some hydrophobicity, but neither achieved superhydrophobicity. Comparing the comparative examples in Table 2 with the examples in Table 1, it is clear that the sponges prepared by the modification method provided by this invention exhibit superior superhydrophobicity compared to the sponges in the comparative examples. The actual contact angles of the three comparative sponges are shown in the table below. Figure 2 As shown in B to D.

[0087] Table 2.

[0088]

[0089] Example 19 Mechanical Performance Test

[0090] Taking the MS-0.5-30-30 sample prepared in Example 2 as an example, the mechanical properties of the hydrophobic modified sponge block were tested using an Instron 5567 universal testing machine. Specifically, using a 100N force sensor, the sponge block was subjected to 50 cycles of compression testing with a maximum deformation of 70% at a loading rate of 5 mm / min.

[0091] The mechanical property test results of the MS-0.5-30-30 sample prepared in Example 2 are as follows: Figure 3 As shown. By comparing the stress-strain curves of each cycle, it can be found that the stress-strain curves of the other cycles, except for the first cycle, almost overlap, indicating that its compressive strength has not changed significantly. Even after 50 cycles of compression in air, the modified sponge block can still return to its original shape after the external force is removed, without plastic deformation or wrinkles.

[0092] Example 20 Oil Absorption Ratio Test

[0093] Taking the sample MS-0.5-30-30 prepared in Example 2 as an example, adsorption tests were conducted on different oils and organic solvents. Specifically, the modified sponge block was placed in the above-mentioned pure liquid without water, allowing it to freely adsorb until saturation. The change in mass of the sponge block before and after adsorption was weighed, and the oil absorption ratio was calculated according to formula (1):

[0094]

[0095] In the formula: Q represents the oil absorption ratio, g / g; m a and m b The numbers represent the mass of the modified sponge block after oil absorption and before oil absorption, respectively, in grams.

[0096] The oil absorption ratio test results of the MS-0.5-30-30 sample prepared in Example 2 are as follows: Figure 4 As shown in the figure, the modified sponge block has excellent oil storage capacity, capable of absorbing 76 to 180 times its own weight in oil or organic solvents. The different oil absorption ratios are mainly due to the differences in density, viscosity, and volatility of the oil and organic solvents.

[0097] Example 21 Durability Test

[0098] Taking the MS-0.5-30-30 sample prepared in Example 2 as an example, its wettability was observed after being placed in an extreme environment for 24 hours. In addition, 50 cycles of oil absorption experiments were conducted on the modified sponge block, and the oil absorption retention rate after 50 cycles was calculated to comprehensively evaluate the durability of the modified sponge block. The oil absorption retention rate was calculated according to formula (2):

[0099]

[0100] In the formula: R represents the oil absorption retention rate, %; Q 50 Q1 and Q2 represent the oil absorption ratios for the 50th and 1st cycles, respectively, in g / g.

[0101] The durability test results of the MS-0.5-30-30 sample prepared in Example 2 are as follows: Figure 5 As shown in the left figure, the modified sponge block maintains good hydrophobicity even after 24 hours of treatment in various extreme environments. In particular, the contact angle remains stable above 150° after immersion in salt water, high-temperature treatment, and ultrasonic treatment with petroleum ether. The slight decrease in contact angle after immersion in acid and alkali solutions and ultrasonic treatment with toluene is mainly due to the corrosion of the polysiloxane on the surface of the modified sponge block by the acid and alkali solutions and the impact of toluene on the Fe in the modified sponge block. 3+ The dilution effect of ions. As shown in the right figure, the modified sponge block maintains good oil absorption capacity after 50 adsorption-extrusion cycles of various oils and organic solvents. Depending on the oil and organic solvent, the oil retention rate ranges from 50.41% to 93.69%, mainly due to the viscosity and volatility of the oil and solvent. Low-viscosity, easily volatile chloroform is almost completely expelled in each cycle and does not remain in the sponge block. Furthermore, cyclic oil absorption testing with chloroform does not cause the sponge block skeleton to collapse, hence its extremely high oil retention rate. Conversely, high-viscosity, non-volatile oils are difficult to completely extrude from the sponge block and gradually accumulate within it, further reducing the oil storage space and causing the sponge block to collapse, resulting in a lower oil retention rate. In summary, the modified sponge block exhibits excellent durability.

[0102] Example 22 Surface morphology observation

[0103] Taking the sample MS-0.5-30-30 prepared in Example 2 as an example, the surface morphology of the modified sponge block after gold sponging was observed using a Thermo Quattro S scanning electron microscope from the Netherlands at an accelerating voltage of 10kV, with an unmodified clean sponge block as a control.

[0104] The scanning electron microscopy results of the MS-0.5-30-30 sample and the unmodified clean sponge block prepared in Example 2 are as follows: Figure 6 As shown. Figure 6 A scanning electron microscope image of an unmodified clean sponge block, which is a three-dimensional porous material composed of a highly interconnected skeleton. The skeleton surface is clean and flat, the skeleton thickness is about 5 μm, and the pore size varies from 100 to 200 μm. Figure 6 B is a scanning electron microscope image of the modified sponge block. The overall porous structure is consistent with the original sponge, but its skeleton surface has micro-nano-sized uneven structures with obvious roughness. This change in surface roughness is one of the reasons for the sponge's transformation from hydrophilic to superhydrophobic.

[0105] Example 23 Pore size distribution and porosity testing

[0106] Taking the MS-0.5-30-30 sample prepared in Example 2 as an example, the pore size distribution and porosity of the modified sponge block were tested using a Micromeritics Autopore IV9500 mercury porosimeter, with an unmodified clean sponge block as a control. Mercury was gradually injected into the sponge under nitrogen pressure. The pore size distribution curve and a series of related parameters can be obtained based on the relationship between pressure and injection volume. This is an effective strategy for characterizing the porous structure of materials (especially macroporous materials, >50 nm).

[0107] The pore size distribution curves of sample MS-0.5-30-30 and unmodified clean sponge block prepared in Example 2 are shown below. Figure 7 As shown in Table 3, the porosity and other related parameters are as follows. According to the pore size distribution curve and parameter table, the sponge blocks before and after modification have the same pore size distribution trend and similar parameter values, indicating that the hydrophobic modification has not changed the porous and lightweight characteristics of the melamine sponge blocks, and they still maintain almost the same hierarchical porous structure.

[0108] Table 3.

[0109]

[0110] Example 24 Chemical Structure Characterization

[0111] Taking the MS-0.5-30-30 sample prepared in Example 2 as an example, the chemical structure of the modified sponge block was characterized using a Nicolet 380 Fourier transform infrared spectrometer (FIR) from the United States, with an unmodified clean sponge block as a control. Specifically: a small amount of dried sample was taken and ground into an extremely fine powder with a trace amount of potassium bromide, pressed into a transparent sheet, and fixed with a clamping tool. Then, the sample was placed together in the infrared spectrometer at 4000–400 cm⁻¹. -1 Scanning is performed within the wavelength range.

[0112] The infrared spectra of sample MS-0.5-30-30 and unmodified clean sponge block prepared in Example 2 are as follows: Figure 8 As shown. Before modification, the original sponge measured 810, 1155, 1539, and 3336 cm⁻¹. -1 The peaks at 985, 1329, and 1471 cm⁻¹ respectively indicate triazine ring bending, C–O stretching, C=N stretching, and N–H (secondary amine) stretching. -1 The peak centered at 2914 cm represents the C–H bend. -1 The absorption peak at that location is due to C–H stretching. After modification, the C–H stretching peak of the superhydrophobic sponge was significantly enhanced and red-shifted to 2968 cm⁻¹. -1This is attributed to the C–H stretching of -CH3 in methylsilanes, and a significant decrease in the N–H stretching peak was also observed. Furthermore, at 766, 1018, 1105, and 1271 cm⁻¹... -1 A distinct Si-O-Si characteristic absorption peak was observed. All of the above comparisons indicate that the sponge has been successfully silanized. This silanization reduces the surface polarity and surface energy of the sponge, which is one of the important mechanisms leading to the sponge's transformation from hydrophilic to superhydrophobic.

[0113] Example 25 Elemental Characterization

[0114] Taking the MS-0.5-30-30 sample prepared in Example 2 as an example, the elemental composition and surface chemical state of the modified sponge block were analyzed using Axis Supra X-ray photoelectron spectroscopy (XPS), with an unmodified clean sponge block as a control. Specifically, the incident radiation was monochromatic Al Kα X-rays, the full-spectrum scan power was 75 W, the high-resolution fine-spectrum scan power was 150 W, and all spectra were calibrated using the C1s peak at 284.6 eV.

[0115] The X-ray photoelectron spectra of the sample MS-0.5-30-30 and the unmodified clean sponge block prepared in Example 2 are as follows: Figure 9 As shown in the diagram, a comparison of the full spectrum reveals that the original sponge exhibits peaks for C, N, O, Na, and S, confirming that the main component of the sponge is a formaldehyde-melamine-sodium bisulfite copolymer. In contrast, additional peaks for Si and Fe were observed in the modified sponge. Furthermore, a comparison of the fine spectrum shows that the O1s peak in the modified sponge is significantly enhanced and shifted towards higher binding energies, while the N1s peak weakens but also shifts towards higher binding energies. The change in peak intensity is due to the polysiloxane film attached to the surface of the sponge skeleton, which introduces more O elements but covers the N elements of the sponge skeleton itself. The shift in binding energy is due to the Fe... 3+ The coordination between N and O atoms, and the low polarity and low surface energy of the metal complex, cause the binding energy of N and O elements to shift to higher directions. This is another mechanism that leads to the transformation of sponges from hydrophilic to superhydrophobic.

[0116] Example 26 Separation of Layered Oil-Water Mixtures

[0117] Taking the sample MS-0.5-30-30 prepared in Example 2 as an example, the separation performance of the modified sponge block on the layered oil-water mixture was studied by adsorption separation method, with an unmodified clean sponge block as a control. Specifically, a certain volume of dyed oil was poured into water to form a layered oil-water mixture. The sponge was placed in the mixture and allowed to freely adsorb until saturation. Then, it was squeezed out and the adsorbed liquid was collected. The above process was repeated until the oil phase could no longer be separated. The change in the volume of the oil phase in the original mixture before and after separation was observed and the separation efficiency was calculated.

[0118] The separation performance of the layered oil-water mixture of sample MS-0.5-30-30 and unmodified clean sponge block prepared in Example 2 is as follows: Figure 10 As shown in the actual images, through multiple adsorption-extrusion processes, the modified sponge block can quickly and completely separate the n-dodecane floating on the surface of the aqueous phase, achieving a separation efficiency close to 100%. In contrast, because the original sponge is amphiphilic, it cannot separate layered oil-water mixtures; the separated liquid remains an oil-water mixture. Furthermore, the modified sponge block can also rapidly and efficiently separate high-density oil phases (such as chloroform) simply by pressing the modified sponge block into the liquid and bringing it into contact with underwater chloroform. In summary, the modified sponge block exhibits excellent separation performance for layered oil-water mixtures.

[0119] Example 27 Separation of Emulsion Oil-Water Mixture

[0120] Taking the superhydrophobic sponge powder prepared in Example 17 as an example, the separation performance of the modified sponge powder for an ideal water-in-oil emulsion model was studied by filtration separation method. Specifically: fluorescein-stained deionized water and oil phase were mixed at a volume ratio of 1:49, and then 0.1 wt% of Span-80 surfactant was added to the above mixture. The mixture was homogenized at 4000 rpm for 2 h to prepare an ideal water-in-oil emulsion model. The above stable emulsion was then poured into a transparent glass tube filled with compacted modified sponge powder at the bottom, and a demulsification experiment was carried out under gravity. The microstructure of the system before and after demulsification was observed using an optical microscope (blue light excitation), and the demulsification flux and demulsification efficiency were calculated to comprehensively evaluate its demulsification performance. The demulsification flux and demulsification efficiency were calculated according to formulas (3) and (4):

[0121]

[0122]

[0123] In the formula: F represents the demulsification flux, L·m -2 ·h -1 V represents the amount of demulsification, L; S represents the cross-sectional area of ​​the glass tube, m. -2 ; t represents the time to break down the milk, h; η d Represents demulsification efficiency, %; c b and c a The values ​​represent the water content of the emulsion and filtrate before and after demulsification, respectively, in %. This value was measured using a Byes 8A micro moisture analyzer.

[0124] The superhydrophobic sponge powder prepared in Example 17 exhibits the following separation performance in an ideal water-in-oil emulsion model: Figure 11As shown in the figure, comparing optical microscopic images before and after demulsification reveals that in the pre-demulsification image, numerous luminescent water droplets ranging from several micrometers to tens of micrometers are randomly distributed in the continuous oil, while in the post-demulsification filtrate image, no luminescent water droplets are observed, and the filtrate is completely black. This qualitatively demonstrates the successful demulsification of the water-in-oil emulsion, and this phenomenon can be explained by the size effect and oil-water selectivity. The demulsification flux and efficiency graphs show that the modified sponge powder exhibits extremely high demulsification efficiency for various ideal water-in-oil emulsion models, ranging from 97.65% to 99.33% depending on the viscosity of the emulsion system. Correspondingly, the demulsification flux decreases exponentially with increasing emulsion viscosity. This is mainly because high-viscosity emulsions can fully contact the modified sponge powder and be completely demulsified.

[0125] Furthermore, considering actual working conditions, a continuous demulsification experiment was conducted on crude oil-salt emulsions at a certain temperature using self-made equipment. Specifically, self-made saline solution was added to crude oil at a volume ratio of 1:4, and 0.1 wt% of Span-80 surfactant and 0.2 wt% of 80-100 mesh quartz sand were added to the mixture. Emulsification was performed using an emulsifying homogenizer at approximately 12,000 rpm for 30 minutes, and the mixture was heated to 40°C to simulate the actual produced fluid from the Changqing Oilfield. Prepared modified sponge powder was loaded into a filter and compacted. The emulsion was pumped into the filter at a flow rate of 30 mL / min using a peristaltic pump for demulsification, and the demulsified liquid was collected at the tail end. The appearance of the system before and after demulsification was observed, and the demulsification efficiency was calculated.

[0126] The mineralization information of the self-made brine is shown in Table 4.

[0127] Table 4.

[0128] ion <![CDATA[Na + ,K + ]]> <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ ]]> <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> <![CDATA[HCO3 - ]]> TDS Concentration (mg / L) 15777.5 4356.3 444.3 31481.5 2190.1 381.6 54700

[0129] The separation performance of the superhydrophobic sponge powder prepared in Example 17 on crude oil-in-salt emulsion is as follows: Figure 12 As shown, the crude oil-in-salt emulsion before demulsification was a turbid brownish-yellow color, while the filtrate after demulsification was pure black, and no quartz sand particles were found in the system. This is because the brine and quartz sand particles in the emulsion were blocked in the filter by the modified sponge powder, and only the crude oil passed through the filter and was collected at the end of the hose. A unit mass of modified sponge powder can demulsify at least 60 mL of crude oil-in-salt emulsion, and the demulsification efficiency is higher than 94%. In summary, the superhydrophobic sponge powder also has excellent separation performance for crude oil-in-salt emulsions, providing a theoretical basis and technical support for the field application of this material in oil fields.

[0130] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art, under the guidance of the present invention, can make many specific modifications without departing from the spirit and scope of the claims, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A method for the production of superhydrophobic sponge material for efficient separation of stratified or emulsified oil-water mixtures, characterized in that, The application comprises the following steps: The modified porous sponge is cleaned with petroleum ether and ethanol respectively and dried; the metal oxide powder is added into the silane modifier, and after 25-35 min of stirring reaction under the air humidity of 30%-80%, the target modification liquid is obtained by filtration; The above cleaned and dried porous sponge is soaked in the target modification liquid, and after 10-150 min of soaking, the residual target modification liquid is squeezed out and dried at 85-95°C to obtain the super-hydrophobic sponge block for high-efficiency separation of layered oil-water mixture; The porous sponge is a commercial sponge with formaldehyde-melamine-sodium bisulfite copolymer as the main component; The metal oxide is ferroferric oxide; The volume fraction of methyltrichlorosilane in the silane modifier is 0.1%-3.0%; the ratio of ferroferric oxide to silane modifier is 2 g of metal oxide powder per 100 mL of silane modifier; The waste sponge block is crushed, cleaned with petroleum ether and ethanol respectively and dried, and modified with the above target modification liquid according to the same method to obtain the super-hydrophobic sponge powder for high-efficiency separation of emulsified oil-water mixture; The waste sponge block is the above super-hydrophobic sponge block that has lost mechanical properties and oil storage capacity after repeated use in separation of layered oil-water mixture.

2. The method of claim 1, wherein, The waste sponge block is crushed by a high-speed crusher, and the rated speed of the crusher is 32000 rpm, and the crushing time is 1-8 min.

3. A super-hydrophobic sponge material prepared by the method of claim 1 or 2.

4. The application of the super-hydrophobic sponge material of claim 3, wherein the super-hydrophobic sponge block is used for separation of layered oil-water mixture, and the super-hydrophobic sponge powder is used for separation of emulsified oil-water mixture.

5. The application of claim 4, wherein the super-hydrophobic sponge powder is used in demulsification of salt water emulsion of oilfield crude oil.

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