A hydrophobic oleophilic aerogel environment-friendly composite material for oil-water separation and a preparation method thereof

Abstract

This invention discloses a hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation, comprising: mixing and stirring a mixture of silicon tetrachloride and magnesite powder, followed by precipitation to obtain a SiO2 / MgSiO3 nano-hybrid material; immersing a melamine sponge in a hexane solution containing monomethyltrichlorosilane, then washing the sponge with ethanol and drying it to obtain a modified porous sponge; hydrolyzing the modified porous sponge in a mixture of glacial acetic acid and ethanol, then adding the SiO2 / MgSiO3 nano-hybrid material and a 10% sodium hydroxide ethanol solution to obtain a second-modified porous sponge; and finally air-drying the second-modified porous sponge in a mixture of trimethylchlorosilane and a monohydric alcohol to obtain the hydrophobic and oleophilic aerogel environmentally friendly composite material. The raw materials used in this invention are inexpensive and readily available, allowing for large-scale industrial production and filling a gap in the market for hydrophobic and oil-absorbing sponge production.

Description

Technical Field

[0001] This invention belongs to the field of oil-water separation, specifically relating to a hydrophobic and oil-absorbing environmentally friendly composite material that can be used for oil-water separation. Background Technology

[0002] With the development of the current electronics and photovoltaic industries, the demand for polysilicon is gradually increasing. Polysilicon production is the most fundamental link in the integrated circuit and photovoltaic industries. However, silicon tetrachloride is generated as a byproduct during polysilicon production, and the production environment is usually a closed space. Silicon tetrachloride decomposes when heated or exposed to moisture, releasing toxic and corrosive fumes that can seriously affect human organs. Improper emissions can also cause serious pollution problems. This invention uses silicon tetrachloride as a raw material to effectively treat the byproduct problem, greatly increasing the recycling rate of silicon tetrachloride and improving environmental benefits.

[0003] Most current oil-absorbing materials are porous materials such as foam and aerogel. Gel-type high-efficiency oil-absorbing materials are expensive, and when oil is squeezed out of the gel, it causes changes to the fragile molecular cross-linked structure of the material, greatly reducing its reusability.

[0004] In the field of oil-absorbing and hydrophobic materials, melamine sponge, as a commercially available polymer sponge material with a three-dimensional porous structure, has become an ideal adsorption substrate material due to its excellent performance. While there are many reports on graphene superhydrophobic sponges among new materials, all of which can achieve oil-water separation, these modification methods suffer from stringent preparation conditions and cumbersome processes, hindering large-scale market production. This invention provides a hydrophobic and oil-absorbing environmentally friendly composite material that can be used for oil-water separation, significantly improving the oil-water separation effect and achieving a high reusability rate, while also possessing environmental and cleaning properties. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation, characterized in that it includes:

[0009] A mixture of silicon tetrachloride and magnesite powder was mixed and stirred before precipitation to obtain SiO2 / MgSiO3 nano-hybrid materials.

[0010] Melamine sponge was soaked in a hexane solution containing methyltrichlorosilane. After the melamine sponge was removed, it was washed with ethanol and dried to obtain a modified porous sponge.

[0011] After hydrolyzing the modified porous sponge in a mixed solution of glacial acetic acid and ethanol, SiO2 / MgSiO3 nano-hybrid material and ethanol solution with sodium hydroxide concentration of 10% were added to obtain the secondary modified porous sponge.

[0012] The modified porous sponge was placed in a mixed solution of trimethylchlorosilane and monohydric alcohol and air-dried naturally to obtain a hydrophobic and oleophilic aerogel environmentally friendly composite material.

[0013] As a preferred embodiment of the preparation method described in this invention, the silicon tetrachloride mixture is a by-product of polycrystalline silicon production, wherein silicon tetrachloride accounts for 72% by mass, trichlorosilane accounts for 27%, and the magnesium carbonate content in the magnesite powder is ≥80%.

[0014] In a preferred embodiment of the preparation method described in this invention, the mass ratio of the silicon tetrachloride mixture to the magnesite powder is 1:0.05-1.

[0015] In a preferred embodiment of the preparation method described in this invention, the n-hexane solution containing monomethyltrichlorosilane is a n-hexane solution with a monomethyltrichlorosilane concentration of 0.3% to 0.7%.

[0016] In a preferred embodiment of the preparation method described in this invention, the mass ratio of glacial acetic acid to ethanol in the glacial acetic acid and ethanol mixed solution is 1:1.1 to 1.5.

[0017] As a preferred embodiment of the preparation method of the present invention, the mixed solution of trimethylchlorosilane and monohydric alcohol has a molar ratio of trimethylchlorosilane to monohydric alcohol of 1:1 to 10:1, and the monohydric alcohol includes, but is not limited to, one or more of methanol, ethanol, propanol, and isopropanol.

[0018] As a preferred embodiment of the preparation method described in this invention, the modified porous sponge is placed in a mixed solution of glacial acetic acid and ethanol for hydrolysis, wherein the hydrolysis time is 1 to 4 hours.

[0019] In a preferred embodiment of the preparation method described in this invention, the porous sponge treated with a mixed solution of trimethylchlorosilane and monohydric alcohol is placed in a container for natural air drying, wherein the air drying time is 5 to 12 hours.

[0020] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation.

[0021] In a preferred embodiment of the preparation method described in this invention, the aerogel environmentally friendly composite material has a specific surface area of ​​167–176 m². 2 / g; the contact angle with surface water is 148°~153°, and the contact angle with oil is >0° and ≤0.2°; it can quickly absorb organic oil stains within 0.02s, and EDX analysis shows that the surface composition contains Si and Mg elements; the average distribution size of the attached silica aerogel is 20nm.

[0022] Beneficial effects of this invention:

[0023] (1) The raw materials of this invention are inexpensive and easy to obtain, and can be used for large-scale industrial production, filling the gap in the market for the production of hydrophobic and oil-absorbing sponges.

[0024] (2) The oil absorption rate and oil absorption capacity of the present invention are significantly improved compared with commercially available sponges.

[0025] (3) The present invention has a high resolution rate, reaching 92% for the first time, with few dead adsorption phenomena and good recyclability.

[0026] (4) The present invention uses the by-products of polycrystalline silicon as raw materials, providing a new way to utilize pollutants. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 The image shows the microscopic contact angle of the original sponge material of this invention, with a water contact angle of 115°.

[0029] Figure 2 The image shows the microscopic contact angle of the composite material in Example 1 of this invention, which has a water contact angle of 153°.

[0030] Figure 3 The image shows the microscopic contact angle of the composite material in Example 2 of this invention, which has a water contact angle of 150°.

[0031] Figure 4 The image shows the microscopic contact angle of the composite material in Example 3 of this invention, which has a water contact angle of 148°.

[0032] Figure 5The image shows the microscopic contact angle of the composite material of Comparative Example 1 of this invention, which has a water contact angle of 131°.

[0033] Figure 6 The image shows the microscopic contact angle of the composite material in Comparative Example 2 of this invention, which has a water contact angle of 151°.

[0034] Figure 7 The image shows the microscopic contact angle of the composite material in Comparative Example 3 of this invention, which has a water contact angle of 114°. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] The silicon tetrachloride mixture used in the examples is a byproduct of polysilicon production, in which silicon tetrachloride accounts for 72% by mass, followed by trichlorosilane, accounting for 27%, which is commercially available, and 1% is impurities.

[0039] The magnesite powder used in the examples is a magnesite sample from the Honghu Minerals brand. After testing, the magnesium carbonate content is 95.7%, which is a common characteristic in the industry and is a commercially available type.

[0040] The melamine sponge used in this example is the LD-1539F model from the Ledian brand, a common commercially available type with a specific surface area of ​​154 m². 2 / g, which has general characteristics of the industry.

[0041] The 0.7% hexane solution of methyltrichlorosilane used in the examples: 8g of chloromethane and 6g of silicon powder were synthesized into a methylchlorosilane mixture under the catalyst of cuprous chloride, and then purified by distillation to 100g of hexane solution to obtain a 0.7% hexane solution of methyltrichlorosilane. It can be diluted with hexane to a 0.3% hexane solution of methyltrichlorosilane.

[0042] The glacial acetic acid solution used in the examples was a high-concentration glacial acetic acid solution of 99.8% from the DAKTARIN brand. The concentration used in the experiment was 30%, which was diluted before use and is a common commercially available type.

[0043] The ethanol solution used in the examples is the Xiaoxianbang brand 98-0 model, with a concentration of 95%, which is a common commercially available type.

[0044] The trimethylchlorosilane used in the examples is the 0-type product from the Ron Reagents brand, with a concentration of 96%, and the solvent is n-hexane, a common commercially available type.

[0045] Example 1

[0046] (1) The mixture of silicon tetrachloride and magnesite powder were mixed at a mass ratio of 1:0.1 and immersed in a ceramic container filled with water. After high-frequency vibration and stirring for 25 min, the mixture was precipitated for 2 h to obtain SiO2 / MgSiO3 nano-hybrid material.

[0047] (2) The melamine sponge was soaked in a hexane solution with a concentration of 0.7% of monomethyltrichlorosilane for 30 minutes. After the sponge was taken out, it was washed with ethanol and dried to obtain the modified porous sponge.

[0048] (3) The modified porous sponge was placed in a mixture of glacial acetic acid and ethanol with a mass ratio of 1:1.3 for 2 hours to hydrolyze. The sponge was then placed in an empty container. SiO2 / MgSiO3 nano-hybrid material and ethanol solution with a sodium hydroxide concentration of 10% were added to the empty container in a ratio of 1:1.7 to obtain the porous sponge after secondary modification.

[0049] (4) The obtained secondary modified porous sponge was placed in a mixed solution of trimethylchlorosilane and ethanol in a molar ratio of 1:5 to complete the silanization treatment, and then air-dried for 7 hours to obtain a hydrophobic and oleophilic aerogel environmentally friendly composite material.

[0050] The composite material obtained in this step was subjected to isothermal adsorption-desorption curves using a BET physical adsorption analyzer. The specific surface area of ​​the product, calculated by the gas adsorption method, was 176 m². 2 / g (using a Micro-3Flex instrument from the USA); the contact angle with surface water was observed to be 153° and the contact angle with oil was close to 0° by microscopic imaging using the water drop method. It can quickly absorb organic oil stains within 0.02s. EDX analysis showed that the surface composition contained Si and Mg elements. TEM particle size analysis showed that the average distribution size of the attached silica aerogel was 20nm, and MgSiO3 and Mg(OH)2 molecules were attached to the surface.

[0051] Example 2

[0052] The difference from Example 1 is that in step (1), the silicon tetrachloride mixture and magnesite powder are in a mass ratio of 1:0.05.

[0053] The composite material obtained through this step has a specific surface area of ​​170 m². 2 / g; the contact angle with surface water is 150°, and the contact angle with oil is close to 0°. It can quickly absorb organic oil stains within 0.02s. EDX analysis shows that the surface composition contains Si and Mg elements. The attached silica aerogel particles are 20nm in size, and MgSiO3 and Mg(OH)2 molecules are attached to the surface.

[0054] Example 3

[0055] The difference from Example 1 is that in step (2), the melamine sponge is soaked in a hexane solution with a methyltrichlorosilane concentration of 0.3% for 30 minutes.

[0056] The specific surface area of ​​the composite material obtained through this step is 167 m². 2 / g; the contact angle with surface water is 148°, and the contact angle with oil is about 0.2°. It can quickly absorb organic oil stains within 0.04s. EDX analysis shows that the surface composition contains Si and Mg elements. The attached silica aerogel particles are 20nm in size, and MgSiO3 and Mg(OH)2 molecules are attached to the surface.

[0057] Comparative Example 1: Lacking the addition of magnesite powder (lacking the reaction step with silicon tetrachloride and magnesium element).

[0058] Silicon tetrachloride was hydrolyzed, and excess sodium hydroxide solution was added. After high-frequency vibration and stirring for 25 min, precipitation was carried out for 2 h to obtain SiO2 hydrogel. Melamine sponge was soaked in a 0.7% hexane solution of monomethyltrichlorosilane for 30 min. The sponge was then removed, washed with ethanol, and dried to obtain modified porous sponge. The modified porous sponge was placed in a 1:1.3 mixture of glacial acetic acid and ethanol for 2 h for hydrolysis. It was then placed in an empty container, and SiO2 hydrogel and 10% anhydrous ethanol of sodium hydroxide concentration were added to the empty container in a 1:2.0 ratio to obtain a second-modified porous sponge. The obtained second-modified porous sponge was placed in a 1:5 mixture of trimethylchlorosilane and monohydric alcohol to complete the silanization treatment. After natural air drying for 7 h, a hydrophobic and oleophilic aerogel environmentally friendly composite material was obtained.

[0059] The specific surface area of ​​the composite material obtained through this step is 179 m². 2 / g; the contact angle with surface water is 131°, and the contact angle with oil is approximately 0.7°. It can rapidly absorb organic oil within 0.13s. EDX analysis shows that the surface composition contains Si element, and the average distribution size of the attached silica aerogel is 18nm. It is evident that the lack of magnesium carbonate raw material leads to a significant decrease in the contact angle with water and a weakening of oil absorption properties.

[0060] Comparative Example 2: A hexane solution with a high concentration of methyltrichlorosilane was used.

[0061] The difference from Example 1 is that in step (2), the melamine sponge is soaked in a hexane solution with a methyltrichlorosilane concentration of 2% for 30 minutes.

[0062] The specific surface area of ​​the composite material obtained through this step is 181 m². 2 / g; the contact angle with surface water is 151°, and the contact angle with oil is close to 0°. It can quickly absorb organic oil stains within 0.02s. EDX analysis shows that the surface has Si and Mg elements. The attached silica aerogel particles are 20nm in size. MgSiO3 and Mg(OH)2 molecules are attached to the surface. It can be seen that although the excess monomethyltrichlorosilane can increase the amount of silane coupling agent modified on the melamine sponge surface, the effect is not obvious.

[0063] Comparative Example 3: The anhydrous ethanol with a sodium hydroxide concentration of 10% in step (3) was replaced with anhydrous ethanol.

[0064] The difference from Example 1 is that in step (3), SiO2 / MgSiO3 nano-hybrid material and ethanol solution are added to an empty container in a ratio of 1:2.0.

[0065] The specific surface area of ​​the composite material obtained through this step is 169 m². 2 / g; the contact angle with surface water is 114°, and the contact angle with oil is close to 0°. It can quickly absorb organic oil stains within 0.03s. EDX analysis shows that the surface has Si and Mg elements. The attached silica aerogel particles are 20nm in size. Dark fibers are attached to the surface. The composite material is dark yellow. It is determined that the surface is complexed with MgSiO3 fibers, which have both oleophilic and hydrophilic properties, which is inconsistent with the original design.

[0066] Comparative Example 4: A hexane solution with a low concentration of methyltrichlorosilane.

[0067] The difference from Example 1 is that in step (1), the melamine sponge is soaked in a hexane solution with a methyltrichlorosilane concentration of 0.1%.

[0068] The specific surface area of ​​the composite material obtained through this step is 163 m². 2 / g; the contact angle with surface water is 142°, and the contact angle with oil is close to 0°. It can quickly absorb organic oil stains within 0.02s. EDX analysis showed that the surface successfully contained Si and Mg elements. The size of the attached silica aerogel particles was 20nm, indicating that MgSiO3 and Mg(OH)2 molecules were attached to the surface. It can be seen that the low concentration of monomethyltrichlorosilane will affect the amount of silane coupling agent modified on the melamine sponge surface.

[0069] Oil absorption test method for oil-absorbing felt:

[0070] 1. Prepare experimental instruments and equipment:

[0071] a) One oil tank, the length and width of which should be larger than the size of the sample to be inspected.

[0072] b) One electronic balance with an accuracy of ±0.01g.

[0073] c) One metal mesh, 40 mesh.

[0074] d) Stopwatch.

[0075] 2. Sample Preparation

[0076] 2.1 Cut oil-absorbing felt samples with dimensions of 10×10cm in accordance with the requirements of GB / T 13760.

[0077] 2.2 For oil-absorbing felts made of fabric-wrapped oil-absorbing particles, a complete oil-absorbing unit can be cut according to the felt structure as an oil-absorbing felt sample.

[0078] 3. Experimental Procedure

[0079] 3.1 Pour oil into the oil tank, with the oil level ≥ 10cm.

[0080] 3.2 Weigh the oil-absorbing felt sample before absorption.

[0081] 3.3 After weighing, place the oil-absorbing felt sample flat in the oil and let it stand for 5 minutes. Then, remove the oil-absorbing felt sample from the oil tank and place it flat on the metal mesh for 5 minutes.

[0082] 3.4 Weigh the oil-absorbing felt sample after oil absorption.

[0083] 3.5 The oil absorption ratio of the oil-absorbing felt sample is calculated according to the following formula (1):

[0084]

[0085] In the formula: R xy - represents the oil absorption ratio of the oil-absorbing felt, in g / g; m oh - is the mass of the oil-absorbing felt sample after absorbing oil and allowing it to stand, in g; m oq - represents the mass of the oil-absorbing felt sample before oil absorption, in grams.

[0086] 4. Experimental Results

[0087] Three sets of oil absorption tests were conducted, and the average oil absorption ratio was taken as the test result.

[0088] Table 1 shows the oil absorption ratio of the composite materials obtained in the examples and comparative examples.

[0089]

[0090]

[0091] The oil absorption ratio is expressed as a percentage. In Example 1, the oil absorption ratio of n-ethane is 31-34, which means that 10g of sponge can absorb 3.1-3.4g of n-ethane.

[0092] Comparative Example 5

[0093] CN 115058057 A discloses a method for preparing and applying hydrophobically modified melamine sponge. The method utilizes vinyltrimethoxysilane and nano-titanium dioxide to perform surface hydrophobic modification on melamine sponge. The method combines nano-titanium dioxide with melamine sponge through a vinyltrimethoxysilane silanization reaction to improve the oil-water selectivity of melamine sponge.

[0094] In Comparative Example 5, titanium dioxide, as a hydrophilic material, exhibits significant oil absorption but lacks obvious oil-water separation properties. During synthesis, titanium dioxide, due to its characteristics, can be directly condensed with melamine sponge (the melamine sponge in the patent) via a silane coupling agent (vinyltrimethoxysilane). However, the nano-silica aerogel ultimately modified in this patent cannot be directly modified onto the melamine sponge surface using a silane coupling agent. This patent obtains a SiO2 / MgSiO3 nano-hybrid material from silicon tetrachloride and magnesite powder, which is first modified onto the sponge surface using a silane coupling agent (monomethyltrichlorosilane), and then silanized to obtain a surface-modified silica aerogel. Regarding material selection, the magnesite powder (low cost) and silicon tetrachloride (waste utilization) used in this process effectively solve the pollution problem in the polysilicon production industry, providing a new approach to pollution control. In contrast, the nano-titanium dioxide used in Comparative Example 5 is expensive and cannot be mass-produced.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing a hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation, characterized in that: include, A mixture of silicon tetrachloride and magnesite powder was mixed and stirred before precipitation to obtain SiO2 / MgSiO3 nano-hybrid materials; Melamine sponge was soaked in a hexane solution containing methyltrichlorosilane. After the melamine sponge was removed, it was washed with ethanol and dried to obtain a modified porous sponge. After hydrolyzing the modified porous sponge in a mixed solution of glacial acetic acid and ethanol, SiO2 / MgSiO3 nano-hybrid material and a 10% sodium hydroxide ethanol solution were added to obtain the secondary modified porous sponge. The modified porous sponge was placed in a mixed solution of trimethylchlorosilane and monohydric alcohol and air-dried naturally to obtain a hydrophobic and oleophilic aerogel environmentally friendly composite material.

2. The preparation method according to claim 1, characterized in that: The silicon tetrachloride mixture is a byproduct of polysilicon production, wherein silicon tetrachloride accounts for 72% by mass, trichlorosilane accounts for 27%, and the magnesium carbonate content in the magnesite powder is ≥80%.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the silicon tetrachloride mixture to the magnesite powder is 1:0.05~1.

4. The preparation method according to claim 1, characterized in that: The n-hexane solution containing monomethyltrichlorosilane is a n-hexane solution with a monomethyltrichlorosilane concentration of 0.3% to 0.7%.

5. The preparation method according to claim 1, characterized in that: In the glacial acetic acid and ethanol mixed solution, the mass ratio of glacial acetic acid to ethanol is 1:1.1~1.

5.

6. The preparation method according to claim 1, characterized in that: The mixed solution of trimethylchlorosilane and monohydric alcohol, wherein the molar ratio of trimethylchlorosilane to monohydric alcohol is 1:1 to 10:1, and the monohydric alcohol includes one or more of methanol, ethanol, propanol, and isopropanol.

7. The preparation method according to claim 1, characterized in that: The modified porous sponge is placed in a mixed solution of glacial acetic acid and ethanol for hydrolysis, wherein the hydrolysis time is 1-4 hours.

8. The preparation method according to claim 1, characterized in that: The porous sponge treated with the mixed solution of trimethylchlorosilane and monohydric alcohol is air-dried naturally for 5 to 12 hours.

9. A hydrophobic and oleophilic aerogel environmentally friendly composite material for oil-water separation prepared by the preparation method according to any one of claims 1 to 8.

10. The aerogel environmentally friendly composite material as described in claim 9, characterized in that: The specific surface area of the aerogel environment-friendly composite material is 167-176 m 2 / g; the contact angle with surface water is 148-153 degrees, the contact angle with oil is >0 degrees and ≤0.2 degrees; the organic oil stain can be quickly absorbed within 0.02 seconds, the surface composition is analyzed by EDX to have Si and Mg elements; the attached silica aerogel has an average distribution size of 20 nm.

Images