Preparation method of low-cost, simple and efficient super-hydrophobic sponge material

Abstract

The invention relates to a preparation method of a low-cost, simple and efficient super-hydrophobic sponge material. Oil liquid leakage, organic solvent leakage and organic waste liquid treatment are hot spots of environmental protection, and preparation of a hydrophobic and oleophylic separation material can solve the problem. The hydrophobic modified sponge material not only can quickly absorb oil and organic liquid, but also can recover the absorbed oil and organic liquid through simple extrusion. Sponge with rich pores, high elasticity and good friction resistance is selected as a modified substrate material, a hydrophobic stock solution is prepared by adopting a one-pot method, hydroxyl silicone oil is used as a raw material of a hydrophobic agent, orthosilicate and polyisocyanates are used as curing cross-linking agents, a micro-nano binary structure is formed on the sponge by utilizing micro-nano silicon dioxide, and the hydrophobic stock solution is prepared by adopting a one-pot method. And the hydrophobicity is further improved by the long-carbon-chain silane coupling agent. The preparation method comprises the following steps: soaking sponge in the hydrophobic stock solution, performing preliminary curing of hydroxyl silicone oil, and then performing vacuumizing, heating and curing, thereby obtaining the super-hydrophobic and super-oleophylic sponge material.

Description

Technical Field

[0001] The invention relates to the modification technology of polymer sponge materials, oil-water separation and organic waste liquid recovery and treatment fields, and in particular to a low-cost, simple and efficient preparation method of super-hydrophobic sponge materials. Background Art

[0002] In modern society, the demand for oil resources is growing day by day. Frequent offshore oil exploration and transportation activities have caused frequent oil spills at sea at home and abroad. On the one hand, the accidents have caused huge economic losses; on the other hand, when oil spills occur, oil will quickly spread in the seawater, pollute the seawater, and form a continuous oil film on the sea surface. The oil film drifts with the ocean current, which not only harms the marine ecology but also has a significant impact on the environmental problems in coastal areas. Similarly, the leakage of organic solvents in chemical plants and the discharge of organic waste liquids have become the main factors that seriously affect the safety of the environment, ecology and water resources. Therefore, how to quickly and efficiently deal with leaked oil, organic solvents and industrial organic waste liquids has become an urgent problem faced by academia and industry, and has also attracted widespread attention from governments and the public. Among the many oil-absorbing materials, sponges have gradually attracted people's attention as a material with strong adsorption capacity, fast absorption speed, light weight and low price. The surface of ordinary unmodified sponges contains hydrophilic groups, which makes the sponges have a certain hydrophilicity. Therefore, the sponges will absorb water while absorbing oil, so that the sponges do not have the ability to separate oil and water. The oil-water separation ability of sponges can be greatly improved through hydrophobic modification technology. According to relevant research, there are currently two methods for hydrophobic modification of sponges: one is to increase the surface roughness of the finished sponge and reduce its surface energy; the other is to change the original formula, add modified substances, and change the reaction conditions during the sponge production process to improve the performance of the sponge.

[0003] Invention patent CN108926874A uses porous, high surface area, degradable chitosan sponge as the substrate, and prepares a superoleophilic / superhydrophobic sponge through two hydrophobic modifications. The sponge has good oil absorption performance, but the raw materials required are expensive and the preparation process is complicated, which greatly limits its practical application.

[0004] Patent CN110387062A uses a dip coating method to apply an organic dispersion of nano-silicon dioxide and MQ silicone resin on the surface of the sponge. During the drying process, as the solvent evaporates, the MQ silicone resin and nano-silicon dioxide separate and deposit on the surface of the sponge. The micro-nano structure and the hydrophobic layer are attached to the surface of the sponge by dip coating. When used repeatedly, they are not firm enough and are easy to fall off, affecting the hydrophobic and lipophilic properties.

[0005] CN103537120A reports that metal oxides are deposited on the surface of a polyurethane sponge skeleton, and then a silane coupling agent is connected to the sponge through the hydroxyl groups on the surface of the oxide to obtain an oil-absorbing sponge. The material prepared by the above method has good oil absorption performance, but the sponge has fatal problems such as poor mechanical stability during use: slight friction or touch will cause the material surface to lose super-hydrophobic and super-oleophilic properties, greatly reducing the oil-water separation effect of the material.

[0006] Gao et al. prepared copper foams of deposited graphene diyne and polydimethylsiloxane (Advanced Materials, 2016, 28, 168-173). These new materials have good oil-water separation performance, but also have the disadvantages of complex preparation process, expensive raw materials, poor durability, etc.

[0007] There are many patents and papers at home and abroad that have studied the hydrophobic modification of various sponge materials. In summary, there are the following shortcomings: ① Expensive raw materials. For example, the use of carbon nanotubes, graphene, silver and other materials; the use of fluorine-containing hydrophobic agents is not only expensive, but also brings environmental problems. ② The steps are cumbersome and time-consuming. ③ The sponge is not chemically bonded to the hydrophobic agent and micro-nano particles, but only physically adsorbed. The hydrophobic layer is easy to fall off and cannot be reused. ④ A large amount of organic solvents such as benzene and toluene are used, and environmental pollution during the preparation process and post-processing is inevitable. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a low-cost, simple and efficient method for preparing a super-hydrophobic sponge material to overcome the deficiencies in the above-mentioned prior art.

[0009] The present invention is achieved through the following technical solutions:

[0010] The present invention discloses a low-cost, simple and efficient method for preparing a super-hydrophobic sponge material, comprising the following steps:

[0011] Step 1: Soak and clean the commercially available sponge with anhydrous ethanol and deionized water, and then dry it in a vacuum at 50-100°C.

[0012] Step 2: Add 100 parts by mass of hydroxy silicone oil, 1-10 parts by mass of orthosilicate, 1-10 parts by mass of polyisocyanate, 0.05-2 parts by mass of organic tin catalyst, 5-15 parts by mass of hydrophilic micro-nano silica, and 2-10 parts by mass of long carbon chain silane coupling agent into a three-necked flask and stir evenly to form a super hydrophobic agent stock solution.

[0013] Step 3: Immerse the above-treated sponge into the super-hydrophobic agent stock solution, stir and react under nitrogen at 60-120°C, take out the sponge after 10-60 minutes, gently squeeze out the liquid in the sponge pores, put it into a vacuum drying oven for vacuum heating and curing at a curing temperature of 60-120°C and a time of 5-30 minutes to obtain a super-hydrophobic sponge material.

[0014] Preferably, the sponge is a polyurethane sponge, a melamine sponge, or a cellulose sponge, with a size of 2 cm*2 cm*2 cm and a pore size of 200-1000 nanometers.

[0015] Preferably, the hydroxy silicone oil has a viscosity of 20-50 mPa·S (25° C.) and a hydroxy content of 4%-10%.

[0016] Preferably, the orthosilicate is methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate.

[0017] Preferably, the polyisocyanate is toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate.

[0018] Preferably, the organotin catalyst is dibutyltin dilaurate, stannous octoate, or dibutyltin diacetate.

[0019] Preferably, the hydrophilic micro-nano silica particles have a diameter of 20 nm-5 um.

[0020] Preferably, the long carbon chain silane coupling agent is dodecyltrimethoxysilane, hexadecyltrimethoxysilane, or octadecyltrimethoxysilane.

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

[0022] The invention discloses a method for preparing a low-cost, simple and efficient super-hydrophobic sponge for oil-water separation. The one-pot method is adopted to include two conditions necessary for preparing super-hydrophobic materials, namely, a hydrophobic agent with hydrophobic modification and micro-nano particles with improved roughness. Hydroxyl silicone oil is used as the main body of the hydrophobic agent, and orthosilicate is used as a curing cross-linking agent. The hydrophobic layer formed after curing contains a large amount of silicon and methyl with low surface energy, which wraps the sponge skeleton and makes it hydrophobic. In order to increase the adhesion between the hydrophobic agent and the sponge skeleton, polyisocyanate is selected as a curing cross-linking agent at the same time. The carbamate formed by the reaction of the polyisocyanate with the hydroxyl silicone oil is also an important component of the polyurethane sponge, thereby increasing the compatibility of the hydrophobic layer with the polyurethane sponge. At the same time, the isocyanate group can react with the carbamate group, amino group and hydroxyl group in the polyurethane sponge, melamine sponge and cellulose sponge, so that the hydrophobic layer and the sponge are chemically bonded, so that it is not easy to fall off. The organotin catalyst can produce a good catalytic effect on the above reaction. The surface of hydrophilic silica micro-nano particles contains a large number of hydroxyl groups, which can undergo curing and cross-linking reactions with hydroxy silicone oil and orthosilicate. The dehydration between the silanol groups forms Si-O-Si bonds, which not only gives the surface of the sponge skeleton a micro-nano binary structure, greatly increases the roughness, but also increases the hydrophobicity. The long carbon chain silane coupling agent hydrolyzes in the system to form silanol groups, which can react with hydroxy silicone oil, orthosilicate, and hydrophilic silica micro-nano particles to form silane ethers, thereby bonding the long carbon chain to the sponge skeleton, further increasing the hydrophobicity.

[0023] The advantages of the present invention are: ① All raw materials are cheap and easily available. ② The one-pot method is adopted, and the preparation process is simple and efficient. The most important curing stage in the reaction process adopts the method of vacuum heating, which can quickly remove small molecules such as water and alcohol generated by the reaction, accelerate the curing speed, and shorten the curing time. ③ The hydrophobic agent and micro-nanoparticles are connected to the sponge in the form of chemical bonds, and the modification effect is firm and stable, and can be reused many times. ④ A particularly outstanding point is that the entire preparation process does not use organic solvents, which is green and environmentally friendly.

[0024] The low-cost, simple and efficient super-hydrophobic sponge for oil-water separation disclosed by the invention is widely used in the recovery and treatment of organic waste liquid, the treatment of oily wastewater and the cleaning of oil leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The following are scanning electron microscope images of the polyurethane sponge before and after hydrophobic modification in Example 1 of the present invention, wherein (a) and (c) are images before modification, magnified 500 times and 20,000 times, respectively; and (b) and (d) are images after modification, magnified 500 times and 20,000 times, respectively.

[0026] Figure 2These are the shape diagrams of water droplets and oil droplets dropped into the polyurethane sponge before and after hydrophobic modification and the corresponding static water contact angle measurement diagrams in Example 1 of the present invention, wherein (a) and (b) are before modification; (c) and (d) are after modification.

[0027] Figure 3 1 is a diagram of the oil-water separation process before and after the hydrophobic modification of the polyurethane sponge in Example 1 of the present invention, wherein (a) is before modification and (b) is after modification. DETAILED DESCRIPTION

[0028] Example 1

[0029] A polyurethane sponge with a size of 2cm*2cm*2cm and an average pore size of 250nm was soaked and cleaned with ethanol and deionized water respectively and then dried. 20g hydroxy silicone oil (viscosity of 25mPa·S), 1.2g ethyl orthosilicate, 1.5g toluene diisocyanate, 0.2g dibutyltin dilaurate, 2g micro-nano hydrophilic silica (particle size 20nm, 100nm, 500nm, 1um, 2um each 0.4g), 1g octadecyl alkyl trimethoxy silane were added to a three-necked flask, nitrogen was passed through, and the above sponge was placed therein after stirring for 10 minutes, and the sponge was taken out after stirring and reacting at 60°C for 30 minutes, and the liquid in the sponge pores was gently squeezed out, and then the sponge was placed in a vacuum drying oven and vacuumed and heated and cured at 60°C for 30 minutes to obtain a super hydrophobic sponge material.

[0030] Example 2

[0031] A melamine sponge with a size of 2cm*2cm*2cm and an average pore size of 200nm was soaked and cleaned with ethanol and deionized water respectively and then dried. 20g hydroxy silicone oil (viscosity of 50mPa·S), 1g methyl orthosilicate, 1.6g isophorone diisocyanate, 0.15g stannous octoate, 2.5g micro-nano hydrophilic silica (particle size 20nm, 50nm, 100nm, 500nm, 1um, each 0.5g), 1.2g hexadecyl alkyl trimethoxy silane were added to a three-necked flask, nitrogen was passed through, and the above sponge was placed in it after stirring for 10 minutes, and the reaction was stirred at 80℃ for 20 minutes. After that, the sponge was taken out, the liquid in the sponge pores was gently squeezed out, and then the sponge was placed in a vacuum drying oven at 80℃ for vacuum heating and curing for 20 minutes to obtain a super hydrophobic sponge material.

[0032] Example 3

[0033] A cellulose sponge with a size of 2cm*2cm*2cm and an average pore size of 500nm was soaked and washed with ethanol and distilled water respectively and then dried. 20g hydroxy silicone oil (viscosity of 50mPa·S), 1.8g butyl orthosilicate, 1.4g hexamethylene diisocyanate, 0.12g stannous octoate, 1.8g micro-nano hydrophilic silica (particle size 100nm, 500nm, 1um, 2um, 5um, each 0.36g), 1g octadecyl alkyl trimethoxy silane were added to a three-necked flask, nitrogen was passed through, and the above sponge was added after stirring for 10 minutes, and the sponge was taken out after stirring and reacting at 90°C for 25 minutes, and the liquid in the sponge pores was gently squeezed out, and then the sponge was placed in a vacuum drying oven at 100°C for vacuum heating and curing for 25 minutes to obtain a super hydrophobic sponge material.

[0034] from Figure 1 It can be seen that the polyurethane sponge skeleton is very clean and smooth before modification, and after modification, the silica micro-nano particles adhere tightly together to form a micro-nano binary structure on the sponge skeleton, making it have sufficient roughness, which is one of the necessary conditions for hydrophobic modification. When combined with low surface energy substances, super hydrophobic materials are obtained. Figure 2 It can be seen that before modification, water droplets and oil droplets on the sponge surface are hemispherical, and the water contact angle is 95°; after modification, water droplets on the sponge surface are spherical, and the water contact angle is 156° and the rolling angle is 5.8°, while the oil droplets are quickly absorbed by the sponge, and the contact angle is 0°. Figure 3 It can be seen that the polyurethane sponge before modification can absorb oil from the water surface, but the oil absorption is not high and there is oil leakage; the modified sponge can quickly absorb all the oil and almost no water, and the oil-water separation effect is excellent. The tested oils include lubricating oil, gasoline, paraffin oil, edible oil, n-hexane, carbon tetrachloride, etc. The oil-water separation effect is relatively good. The modified sponge can absorb 50-65 times its own weight of oil. After repeating the test 20 times, the oil absorption did not change. After 50 times, the oil absorption was 98% of the maximum amount. After 100 times, the oil absorption can still reach 92%, indicating that the modified sponge hydrophobic layer is firmly combined with the sponge and can be reused.

[0035] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material, characterized in that: The specific steps include: (1) Select commercially available sponges, soak and wash them with anhydrous ethanol and deionized water, and dry them in a vacuum at 50-100°C; (2) adding 100 parts by mass of hydroxy silicone oil, 1-10 parts by mass of orthosilicate, 1-10 parts by mass of polyisocyanate, 0.05-2 parts by mass of organotin catalyst, 5-15 parts by mass of hydrophilic micro-nano silica, and 2-10 parts by mass of long carbon chain silane coupling agent into a three-necked flask and stirring to form a super hydrophobic agent stock solution; (3) Immerse the treated sponge into the super-hydrophobic agent stock solution, stir and react under nitrogen at 60-120° C., take out the sponge after reacting for 10-60 minutes, gently squeeze out the liquid in the sponge pores, put it into a vacuum drying oven for vacuum heating and curing, the curing temperature is 60-120° C., and the time is 5-30 minutes, so as to obtain a super-hydrophobic sponge material.

2. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The sponge in (1) refers to various commercially available sponges, including polyurethane sponge, melamine sponge, cellulose sponge, with a size of 2cm*2cm*2cm and a pore size of 200-1000 nanometers.

3. A low-cost, simple and efficient method for preparing a super hydrophobic sponge material according to claim 1, characterized in that: The hydroxy silicone oil in (2) has a viscosity of 20-50 mPa·S (25° C.) and a hydroxy content of 4%-10%.

4. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The orthosilicate in (2) is methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate.

5. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The polyisocyanate in (2) is toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or dicyclohexylmethane diisocyanate.

6. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The organic tin catalyst in (2) is dibutyltin dilaurate, stannous octoate, or dibutyltin diacetate.

7. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The hydrophilic micro-nano silica particles in (2) have a particle size of 20nm-5um.

8. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The (2) medium-long carbon chain silane coupling agent is dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

9. A low-cost, simple and efficient method for preparing a super-hydrophobic sponge material according to claim 1, characterized in that: The low-cost, simple and efficient super-hydrophobic sponge material prepared is used in the fields of oil-water separation and recovery and treatment of organic waste liquid.

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