Superhydrophobic bacterial cellulose, its preparation, and its application in the remediation of water pollutants.

Abstract

This invention discloses a superhydrophobic bacterial cellulose, its preparation method, and its applications. The superhydrophobic bacterial cellulose is a superhydrophobic material formed by grafting vinyl laurate onto the surface of bacterial cellulose through a silane coupling agent. The preparation method of this invention is simple, mild, and allows for controllable conditions, and is expected to achieve efficient adsorption and removal of pollutants in lake water, providing theoretical support and technical guidance for lake water environment management.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and relates to a superhydrophobic bacterial cellulose, its preparation method, and its application in the remediation of pollutants in lake water. Background Technology

[0002] Lakes, a vital source of water resources for human survival, are a gift from nature. However, with industrialization, organic pollution has become a pressing issue for lake water environments. Industrial pollution sources are currently the largest source of organic pollution, including industrial waste discharge, the extensive use of pesticides in agriculture, and the direct discharge of domestic wastewater. These organic compounds enter lakes through surface runoff, atmosphere-water exchange, atmospheric deposition, and groundwater infiltration. Once in lakes, these organic compounds migrate and transform through physical, chemical, and biological processes. Biomigration and transformation are crucial pathways by which toxic organic pollutants in lake systems cause environmental harm. These substances are hydrophobic and can accumulate in biological fats. Therefore, even low concentrations in lakes can cause persistent toxicity through the aquatic food chain, potentially harming human health.

[0003] Lake organic pollutants contain a large amount of oily substances, such as n-hexane and toluene, which hinder light penetration into the water and reduce dissolved oxygen levels. Therefore, the removal of oily pollutants is crucial. Currently, a large number of carbon-based adsorbent materials are used in water pollution remediation processes. However, most traditional adsorbent materials, such as activated carbon, are in powder form, making reuse and effective recycling impossible. Studies have shown that novel adsorbent materials can achieve highly efficient removal of pollutants from lake water, but their high cost and complex processes limit their large-scale application in lake water pollution remediation. Furthermore, many currently used adsorbent materials cannot be naturally degraded by the environment, causing secondary pollution of the water environment. Therefore, designing and preparing a class of low-cost, simple-process, and stable environmentally friendly adsorbent materials holds promise for breaking through the bottlenecks in the application of adsorbent materials in lake water pollution remediation. Summary of the Invention

[0004] The purpose of this invention is to provide a superhydrophobic bacterial cellulose, its preparation method, and its application in the remediation of pollutants in lake water. This invention uses bacterial cellulose, a low-cost and widely available polymeric biomass material, as the substrate. By in-situ grafting vinyl lauryl ester (Vi-La), it acquires superhydrophobic properties while achieving environmental friendliness. This improves the hydrophobicity of Vi-La and enhances the adsorption properties of the grafted Vi-La molecules, thereby effectively adsorbing organic pollutants in lakes. Furthermore, it possesses excellent mechanical properties and is easily reusable.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A superhydrophobic bacterial cellulose, which is a superhydrophobic material formed by grafting vinyl laurate onto the surface of bacterial cellulose through a silane coupling agent.

[0007] Preferably, the vinyl lauryl ester is grafted onto the surface of the bacterial cellulose via an in-situ reaction.

[0008] Preferably, the silane coupling agent is vinyltrimethoxysilane.

[0009] Preferably, the vinyl lauryl ester is linked to the alkenyl group of the silane coupling agent by a polymerization reaction.

[0010] The present invention also provides a method for preparing the above-mentioned superhydrophobic bacterial cellulose, comprising the following steps:

[0011] (1) Bacterial cellulose (BC) and silane coupling agent were reacted and then dried to obtain a composite material;

[0012] (2) The composite material, initiator and vinyl laurate obtained in step (1) are reacted in a solvent and then dried to obtain the superhydrophobic bacterial cellulose.

[0013] Preferably, the reaction described in step (1) is carried out in an aqueous solvent.

[0014] Preferably, the aqueous solvent is an ethanol-water mixture.

[0015] Preferably, the volume ratio of ethanol to water in the aqueous solvent is 1:1.

[0016] Preferably, the reaction temperature in step (1) is 60°C.

[0017] Preferably, the reaction time in step (1) is 6 hours.

[0018] Preferably, the drying process described in step (1) or step (2) is freeze drying.

[0019] Preferably, the molar ratio of the silane coupling agent to the terminal hydroxyl group of the bacterial cellulose in step (1) is 10:1 to 1:2.

[0020] Preferably, the initiator in step (2) is a free radical polymerization initiator.

[0021] Preferably, the initiator is azoisobutyronitrile.

[0022] Preferably, the solvent in step (2) is an alcohol solvent.

[0023] Preferably, the alcohol solvent is methanol.

[0024] Preferably, the ratio of the composite material, initiator, and vinyl lauryl ester used in step (2) is 1:0.1~0.5:1~5.

[0025] Preferably, the reaction temperature in step (2) is 40 ~ 80 ℃, and most preferably 60 ℃.

[0026] Preferably, the reaction time in step (2) is 4 to 8 hours. Most preferably, it is 6 hours.

[0027] The present invention also provides the application of the superhydrophobic bacterial cellulose in the remediation of water pollutants.

[0028] Compared with the prior art, the advantages of this invention are:

[0029] (1) The method of the present invention is simple and convenient, low in cost, and requires mild reaction conditions.

[0030] (2) The superhydrophobic bacterial cellulose prepared by this invention has a high adsorption capacity and fast adsorption kinetics. It also has good stability and can maintain a high adsorption capacity in complex water environments.

[0031] (3) In addition to superhydrophobic properties, the superhydrophobic bacterial cellulose prepared by this invention has higher chemical crystallinity, higher chemical purity, better mechanical properties, and is more durable than traditional cellulose.

[0032] (4) The superhydrophobic bacterial cellulose prepared by the present invention is obtained by in-situ grafting of hydrophobic long chains. Compared with hydrophobic materials prepared by direct loading in situ, the present invention can effectively improve the utilization rate of hydrophobic long chains and avoid the steric hindrance between macromolecules.

[0033] (5) The superhydrophobic bacterial cellulose prepared by the present invention has better hydrophobicity than the hydrophobic material itself. The main reason is that by in-situ grafting, the structure and arrangement of the hydrophobic long chains can be effectively changed. In particular, the ultrafine nanofibers of bacterial cellulose can make the hydrophobic long chains arranged in an orderly manner on its surface, effectively improving its hydrophobic properties. Attached Figure Description

[0034] Figure 1 These are optical photographs of BC and BC / Vi-La; among them Figure 1 (a) is an optical photograph of BC. Figure 1 (b) is an optical photograph of the BC / Vi-La composite material prepared according to the present invention.

[0035] Figure 2 This is a comparison chart of the water contact angles of BC / Vi-La prepared with different amounts of A171.

[0036] Figure 3 This is a comparison chart of the adsorption capacity of BC / Vi-La prepared with different amounts of Vi-La for oily pollutants in water.

[0037] Figure 4 This is a comparison chart of the adsorption capacity of BC / Vi-La prepared with different amounts of AIBN for oily pollutants in water.

[0038] Figure 5 This is a comparison chart of the adsorption capacity of BC / Vi-La prepared at different reaction temperatures for oily pollutants in water.

[0039] Figure 6 This is a comparison chart of the adsorption capacity of BC / Vi-La prepared at different reaction times for oily pollutants in water.

[0040] Figure 7 This is a comparison chart of the adsorption capacity of BC / Vi-La-1 for oily pollutants in water under different pH environments.

[0041] Figure 8 This is a comparison chart of the adsorption capacity of BC / Vi-La-1 for oily pollutants in water under different inorganic anion conditions.

[0042] Figure 9 This is a comparison chart of the adsorption capacity of BC / Vi-La-1 for oily pollutants in water bodies under the condition of dissolved organic matter.

[0043] Figure 10 This is a comparison chart of the water contact angles of BC / Vi-La-1, Vi-La superhydrophobic materials, and BC / Vi-La-22.

[0044] Figure 11 This is a comparison chart of the adsorption capacity of BC / Vi-La-1, Vi-La superhydrophobic materials and BC / Vi-La-22 for oily pollutants in water. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings, embodiments, and comparative examples.

[0046] Example 1

[0047] 1. Preparation of superhydrophobic bacterial cellulose:

[0048] Step 1: Take a bacterial cellulose (BC) membrane (30 mm × 30 mm) and immerse it in a mixed solution of ethanol and water (volume ratio 1:1).

[0049] Step 2: Add vinyltrimethoxysilane (A171) to the solution obtained in Step 1, and react at 60 °C for 6 hours under the condition of cooling circulating water bath. Then, take out the sample, wash it repeatedly with ethanol and water, and freeze-dry to obtain BC-A171 composite material.

[0050] Step 3: Immerse the BC-A171 composite material obtained in Step 2 and vinyl lauryl ester (Vi-La) in methanol, and then slowly add azobisisobutyronitrile (AIBN).

[0051] Step 4: The solution obtained in Step 3 is reacted under cooling circulating water bath conditions. The final product is washed with water and then freeze-dried (10 Pa, -40 ℃) to obtain BC / Vi-La superhydrophobic bacterial cellulose material.

[0052] Optical photographs of BC and BC / Vi-La before and after grafting, as shown below. Figure 1 As shown.

[0053] By adjusting the amounts of A171, Vi-La, and AIBN in the preparation process, a series of materials were obtained. The specific amounts and the materials obtained are shown in Table 1.

[0054] Table 1. Relationship between raw material dosage, reaction temperature, and obtained materials during the preparation process.

[0055] Name of the material produced A171 (mmol) Vi-La (mmol) AIBN (mmol) Reaction temperature (°C) Reaction time (h) BC / Vi-La-1 0.1 0.03 0.02 60 6 BC / Vi-La-2 0.01 0.03 0.02 60 6 BC / Vi-La-3 0.05 0.03 0.02 60 6 BC / Vi-La-4 0.15 0.03 0.02 60 6 BC / Vi-La-5 0.05 0.03 0.02 60 6 BC / Vi-La-6 0.1 0.01 0.02 60 6 BC / Vi-La-7 0.1 0.02 0.02 60 6 BC / Vi-La-8 0.1 0.04 0.02 60 6 BC / Vi-La-9 0.1 0.05 0.02 60 6 BC / Vi-La-10 0.1 0.03 0.01 60 6 BC / Vi-La-11 0.1 0.03 0.03 60 6 BC / Vi-La-12 0.1 0.03 0.04 60 6 BC / Vi-La-13 0.1 0.03 0.05 60 6 BC / Vi-La-14 0.1 0.03 0.02 40 6 BC / Vi-La-15 0.1 0.03 0.02 50 6 BC / Vi-La-16 0.1 0.03 0.02 70 6 BC / Vi-La-17 0.1 0.03 0.02 80 6 BC / Vi-La-18 0.1 0.03 0.02 60 4 BC / Vi-La-19 0.1 0.03 0.02 60 5 BC / Vi-La-20 0.1 0.03 0.02 60 7 BC / Vi-La-21 0.1 0.03 0.02 60 8 BC / Vi-La-22 0.1 0.03 0.02 60 6 Vi-La superhydrophobic material 0 0.03 0.02 60 6

[0056] 2. Hydrophobicity test of BC / Vi-La superhydrophobic bacterial cellulose

[0057] A relatively flat surface of different materials was selected, and the contact angle of different materials was measured using a contact angle meter. Contact angle images were captured by a high-speed camera, and the water contact angle was calculated using Young's equation.

[0058] The results are as follows Figure 2 As shown, the water contact angle of BC / Vi-La is positively linearly correlated with the amount of A171 used. When the amount of A171 is increased to 0.1 mmol, the water contact angle reaches 153.68°. Further increasing the amount of A171 cannot increase the contact angle further. Therefore, the optimal amount of A171 is 0.1 mmol.

[0059] 3. Adsorption performance test of BC / Vi-La superhydrophobic bacterial cellulose:

[0060] Step 1: Select n-hexane (5 mL) as an oily model pollutant and add it to 100 mL of water to simulate polluted water.

[0061] Step 2: Weigh 10 mg of BC / Vi-La superhydrophobic bacterial cellulose and add it to the polluted water. Adjust the pH using hydrochloric acid and sodium hydroxide.

[0062] Step 3: After the adsorption is complete, the BC / Vi-La superhydrophobic bacterial cellulose is removed from the solution, freeze-dried, weighed, and analyzed for adsorption capacity.

[0063] Step 4: Sonicate desorption in a methanol solution containing 0.1 mol / L NaOH, then wash multiple times with ethanol and pure water, freeze-dry for use in cyclic experiments.

[0064] In step 1, you may choose to add or not add inorganic anions and dissolved organic matter.

[0065] In step 2, the solution pH value can be selected as 5.0, 6.0, 7.0, 8.0, or 9.0.

[0066] The specific test conditions are shown in Table 2:

[0067] Table 2. Test conditions for adsorption performance of superhydrophobic bacterial cellulose

[0068] Test number pH conditions for adsorption Other interfering substances and their concentrations in the environment 1 7.0 none 2 5.0 none 3 6.0 none 4 8.0 none 5 9.0 none 6 7.0 100 mg / L, NaCl 7 7.0 <![CDATA[100 mg / L,Na2CO3]]> 8 7.0 <![CDATA[100 mg / L,Na2SO4 <!-- 4 -->]]> 9 7.0 <![CDATA[100 mg / L,NaNO3]]> 10 7.0 100 mg / L, HA 11 7.0 100 mg / L, BSA

[0069] Adsorption capacity test results are as follows Figure 3-6 As shown.

[0070] like Figure 3 As shown, the amount of Vi-La affects the hexane adsorption capacity of BC / Vi-La. The results indicate that the adsorption capacity of the material increases with the increase of Vi-La amount. When the Vi-La amount reaches 0.03 mmol, the adsorption capacity of the material reaches 3.295 g / 10 mg. Further increasing the Vi-La amount does not significantly increase the adsorption capacity of the material.

[0071] like Figure 4 As shown, the amount of AIBN affects the hexane adsorption capacity of BC / Vi-La. With the increase of AIBN amount, the adsorption capacity of the material increases. When the amount of AIBN reaches 0.02 mmol, the adsorption capacity of the material reaches 3.295 g / 10 mg. Further increasing the amount of AIBN does not result in a significant increase in the adsorption capacity of the material.

[0072] like Figure 5 As shown, the reaction temperature affects the hexane adsorption capacity of BC / Vi-La. With the increase of reaction temperature, the adsorption capacity of the material shows a trend of first increasing and then leveling off. When the reaction temperature reaches 60 °C, the adsorption capacity of the material reaches 3.295 g / 10 mg.

[0073] like Figure 6As shown, the reaction time affects the hexane adsorption capacity of BC / Vi-La. With the extension of the reaction time, the adsorption capacity of the material shows a trend of first increasing and then leveling off. When the reaction time reaches 6 h, the adsorption capacity of the material reaches 3.295 g / 10 mg.

[0074] Therefore, the optimal conditions for preparing BC / Vi-La are: controlling the amount of A171 to 0.1 mmol, the amount of Vi-La to 0.03 mmol, the amount of AIBN to 0.02 mmol, the reaction temperature to 60 ℃, and the reaction time to 6 h.

[0075] like Figure 7 As shown, the BC / Vi-La-1 composite material maintained an adsorption capacity of 3.295 g / 10 mg across a wide pH range (5–9); a system without any added substances was selected as the control group. Figure 8 , 9 It can be seen that the adsorption of n-hexane by the BC / Vi-La-1 composite material is less affected by inorganic anions and dissolved organic matter, demonstrating the material's excellent environmental adaptability.

[0076] 4. Comparison of hydrophobic properties of BC / Vi-La superhydrophobic bacterial cellulose

[0077] comprehensive Figure 10 The results show that the water contact angle of the in-situ grafted composite material is higher than that of the directly polymerized superhydrophobic material and also higher than that of the loaded superhydrophobic material, indicating that in-situ grafting can effectively improve the hydrophobicity of the material. Figure 11 The results show that the adsorption capacity of the composite material grafted in situ is higher than that of the directly polymerized superhydrophobic material and also higher than that of the loaded superhydrophobic material, indicating that in situ grafting can effectively improve the adsorption capacity of the material.

[0078] In summary, the BC / Vi-La composite material prepared by this invention has good practical application prospects in the remediation of lake water pollution.

Claims

1. A superhydrophobic bacterial cellulose, characterized in that, It is a superhydrophobic material formed by grafting vinyl laurate onto the surface of bacterial cellulose with a silane coupling agent; the vinyl laurate is connected to the alkenyl group of the silane coupling agent by a polymerization reaction; the molar ratio of the silane coupling agent to the terminal hydroxyl group of the bacterial cellulose is 10:1 to 1:

2.

2. The method for preparing the superhydrophobic bacterial cellulose according to claim 1, characterized in that, Includes the following steps: (1) After reacting bacterial cellulose and silane coupling agent, the mixture is dried to obtain a composite material; (2) The composite material, initiator and vinyl laurate obtained in step (1) are reacted in a solvent and then dried to obtain the superhydrophobic bacterial cellulose.

3. The preparation method according to claim 2, characterized in that, The reaction described in step (1) is carried out in an aqueous solvent.

4. The preparation method according to claim 3, characterized in that, The aqueous solvent is an ethanol-water mixture.

5. The preparation method according to claim 4, characterized in that, The volume ratio of ethanol to water in the aqueous solvent is 1:

1.

6. The preparation method according to claim 2, characterized in that, The reaction temperature in step (1) is 60°C; the reaction time is 6 hours.

7. The preparation method according to claim 2, characterized in that, The initiator mentioned in step (2) is a free radical polymerization initiator.

8. The preparation method according to claim 7, characterized in that, The initiator is azoisobutyronitrile.

9. The preparation method according to claim 2, characterized in that, The solvent mentioned in step (2) is an alcohol solvent.

10. The preparation method according to claim 9, characterized in that, The alcohol solvent is methanol.

11. The preparation method according to claim 2, characterized in that, The reaction temperature in step (2) is 40 ~ 80 °C; the reaction time is 4 ~ 8 h.

12. The preparation method according to claim 11, characterized in that, The reaction temperature is 60°C, and the reaction time is 6 hours.

13. The application of the superhydrophobic bacterial cellulose of claim 1 in the remediation of water pollutants.

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