Carbonic anhydrase catalyzed co2 mineralization reinforced bamboo fiber composite material and preparation method thereof

Abstract

The application discloses a kind of carbonic anhydrase catalysis CO2 Mineralization enhanced bamboo fiber composite material and preparation method thereof, belong to environmental protection material field.The composite material formula includes by weight parts 15-20 parts of terephthalic acid, 1,4-butanediol 16-25 parts, catalyst 0.2-1 part, bamboo fiber 50-55 parts, calcium chloride 5-8 parts, carbonic anhydrase 0.01-0.03 parts, pH regulator 1-2 parts, antioxidant 0.3-1 part.The preparation process is first used carbonic anhydrase mineralization bamboo fiber, and obtains mineralization bamboo fiber, and PBT is synthesized under the catalysis of catalyst to obtain mineralization bamboo fiber-PBT copolyester composite material.The composite material prepared by the scheme has the characteristics of degradability, low cost, good interfacial compatibility and excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly materials, and in particular to a carbonic anhydrase-catalyzed CO2 mineralization-enhanced bamboo fiber composite material and its preparation method. Background Technology

[0002] Bamboo fiber possesses advantages such as high specific strength, high specific modulus, wide availability, low price, renewability, and biodegradability, earning it the reputation of "green fiber" and "natural glass fiber." Composite materials synthesized with bamboo fiber as reinforcement and other materials are resource-saving and environmentally friendly green building materials. They can replace wood, plastics, and steel, possessing extremely high economic, ecological, and social value. Research by scholars both domestically and internationally has shown that bamboo fiber can significantly enhance the properties of polymers and inorganic materials.

[0003] Terephthalic acid and 1,4-butanediol can be polymerized to form a high molecular weight polymer material (PBT). PBT has excellent rigidity, dimensional stability, low moisture absorption, high strength, fatigue resistance, and wear resistance, but it is notch sensitive (prone to stress cracking), has poor hydrolysis resistance, and insufficient low-temperature toughness. To address these shortcomings, it is often blended with other polymer materials to enhance its mechanical properties.

[0004] PBT is a polyester polymer containing easily hydrolyzable ester bonds. It is readily degraded by enzymes under microbial action, making it an environmentally friendly thermoplastic. Fiber-reinforced composites are a new type of material made by combining fiber materials with a polymer matrix through a composite process. They possess excellent properties such as lightweight, high strength, fatigue resistance, creep resistance, and corrosion resistance, and are widely used in construction, aerospace, and transportation. Glass fibers and carbon fibers are commonly used to modify PBT; however, poor interfacial compatibility and structural uniformity between these fibers and the polymer matrix are bottlenecks restricting its development, resulting in limited performance improvements in the prepared composites.

[0005] Carbonic anhydrase is a zinc-containing enzyme widely found in living organisms. It can catalyze the reaction of carbon dioxide and water to produce carbonate ions, playing an important role in mineralization and deposition. It has been successfully applied in reducing carbon dioxide emissions. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a carbonic anhydrase-catalyzed CO2 mineralization-reinforced bamboo fiber composite material. Another purpose of this invention is to provide a method for preparing a carbonic anhydrase-catalyzed CO2 mineralization-reinforced bamboo fiber composite material, so as to solve the defects in the above-mentioned background technology, such as poor interfacial compatibility and poor structural uniformity between fiber materials and polymers.

[0007] Technical solution: A carbonic anhydrase-catalyzed CO2 mineralization-enhanced bamboo fiber composite material, characterized in that the formula contains, by weight, 15-20 parts of terephthalic acid, 16-25 parts of 1,4-butanediol, 0.2-1 parts of catalyst, 50-55 parts of bamboo fiber, 5-8 parts of calcium chloride, 0.01-0.03 parts of carbonic anhydrase, 1-2 parts of pH adjuster, and 0.3-1 parts of antioxidant.

[0008] Preferably, the catalyst is tetraethyl titanate and stannous octoate.

[0009] Preferably, the pH adjuster is one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, or sodium carbonate aqueous solution.

[0010] Preferably, the antioxidant is one of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0011] A method for preparing a carbonic anhydrase-catalyzed CO2 mineralization-reinforced bamboo fiber composite material includes the following steps:

[0012] S1: Add bamboo fiber, carbonic anhydrase, and calcium chloride to a phosphate buffered saline (PBS) solution with a pH of 6.2-8.9 according to the formula ratio, stir and mix evenly to obtain reaction solution 1, wherein the weight ratio of the buffered saline solution to bamboo fiber is 10:1.

[0013] S2: Pass CO2 gas into reaction solution 1 prepared in step S1, control the system temperature at 10-40℃, add pH adjuster solution dropwise, control the pH of the reaction solution at 5-8, until the system no longer absorbs CO2 gas, and obtain reaction solution 2.

[0014] S3: Filter the reaction solution 2 prepared in step S2, wash the filter residue with deionized water until neutral, and dry the washed filter residue to remove moisture to obtain mineralized cellulose.

[0015] S4: Mix terephthalic acid, 1,4-butanediol and tetraethyl titanate catalyst evenly according to the formula. Under the protection of an inert gas atmosphere, heat to 190-250℃ and stir for 6-10 hours. After the reaction is completed, cool the reaction solution to 60-80℃ and remove the by-reaction products by vacuum distillation to obtain polybutylene terephthalate.

[0016] S5: Add the mineralized cellulose prepared in step S3 to the polybutylene terephthalate prepared in step S4, then add the catalyst stannous octoate, heat to 250-300℃ and stir for 2-4 hours in an inert gas stream, add an antioxidant to the reaction system and stir for 30 minutes to obtain carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material.

[0017] Preferably, in step S1, the length of the bamboo fiber is 8-17 mm.

[0018] Preferably, in step S2, the mass concentration of the pH adjuster solution is 10-20%.

[0019] Preferably, in step S3, the water content of the mineralized cellulose is not higher than 0.3%.

[0020] Preferably, in step S4, the inert gas is one of carbon dioxide, nitrogen, or argon.

[0021] Beneficial effects:

[0022] (1) This invention uses carbonic anhydrase to catalyze the hydration reaction of carbon dioxide, generating carbonate ions, which then react with calcium ions in the formula to form calcium carbonate precipitate, thereby achieving the purpose of mineralizing bamboo fiber. Since bamboo fiber can uniformly adsorb carbonic anhydrase in the formula, carbonic anhydrase then catalyzes CO2 and water to hydrate efficiently. The generated carbonate ions then react with CaCl2, and the precipitated CaCO3 particles are evenly distributed and uniformly attached to the bamboo fiber. This avoids the problems of poor uniformity, easy aggregation of calcium carbonate, and increased particle size of calcium carbonate caused by directly using calcium carbonate and bamboo fiber in physical blending.

[0023] (2) After terephthalic acid and 1,4-butanediol are copolymerized to form polybutylene phthalate (PBT) polymer, bamboo fiber contains a large number of hydroxyl groups in its molecular structure. Under the action of a catalyst, bamboo fiber reacts with PBT through transesterification and esterification reactions and then couples to form bamboo fiber-PBT copolyester. This solves the problem of poor interfacial compatibility between bamboo fiber and PBT and improves the mechanical properties of the composite material.

[0024] (3) The mineralized bamboo fiber obtained by mineralizing bamboo fiber with carbonic anhydrase can further enhance the bonding force between bamboo fiber and PBT when it is copolymerized with PBT to form a composite material, compared with the unmineralized bamboo fiber. The structure is more uniform and the mechanical properties of bamboo fiber-PBT copolyester are further improved.

[0025] (4) Both PBT and bamboo fiber are biodegradable materials. The composite material prepared is a new type of environmentally friendly material. Bamboo fiber is widely available and has low cost. Attached Figure Description

[0026] Figure 1 Thermogravimetric analysis (TGA) diagrams of the composite materials prepared in Example 1 and Comparative Example 1 are shown. Detailed Implementation

[0027] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0028] Example 1

[0029] Add 55 kg of bamboo fiber with an average length of 15 mm, 0.03 kg of carbonic anhydrase, 8 kg of calcium chloride, and 550 kg of phosphate buffered saline (PBS) solution with a pH of 8.9 to a reaction vessel, and stir to mix evenly.

[0030] Introduce CO2 gas into the above reaction solution, control the system temperature at 10-40℃, add 20% NaOH aqueous solution dropwise to adjust the pH of the reaction solution, control the pH of the reaction solution at 5-8, until the system no longer absorbs CO2 gas, consuming approximately 2 kg of NaOH aqueous solution, and then stop the reaction.

[0031] The above reaction solution was centrifuged and filtered. The filtrate could be recycled. The filter residue was washed with deionized water until neutral. The washed filter residue was dried at 80°C to remove moisture. The moisture content was measured to be 0.2%, and mineralized cellulose was obtained.

[0032] Add 20 kg of terephthalic acid, 25 kg of 1,4-butanediol, and 0.5 kg of tetraethyl titanate catalyst to another reaction vessel, stir and mix evenly, evacuate the reaction vessel and replace it with nitrogen, heat to 250℃ and stir for 6 hours. After the reaction is completed, cool the reaction solution to 80℃ and remove the by-reaction products by vacuum distillation to obtain polybutylene terephthalate.

[0033] Mineralized cellulose was added to the above reaction vessel, followed by 0.5 kg of stannous octoate catalyst. Nitrogen gas was introduced into the reaction vessel, and the temperature was raised to 300°C and stirred for 2 hours. Then, 1 kg of antioxidant 1010 was added and stirred for 30 minutes to obtain CO2 mineralized reinforced bamboo fiber composite material 1.

[0034] Example 2

[0035] Add 50 kg of bamboo fiber with an average length of 8 mm, 0.01 kg of carbonic anhydrase, 5 kg of calcium chloride, and 500 kg of phosphate buffered saline (PBS) solution with a pH of 6.2 to the reaction vessel, and stir to mix evenly.

[0036] Introduce CO2 gas into the above reaction solution, control the system temperature at 10-40℃, add 15% KOH aqueous solution dropwise to adjust the pH of the reaction solution, control the pH of the reaction solution at 5-8, until the system no longer absorbs CO2 gas, consuming about 1 kg of KOH aqueous solution, and then stop the reaction.

[0037] The above reaction solution was centrifuged and filtered. The filter residue was washed with deionized water until neutral. The washed filter residue was dried at 80°C to remove moisture. The moisture content was measured to be 0.3%, and mineralized cellulose was obtained.

[0038] Add 15 kg of terephthalic acid, 16 kg of 1,4-butanediol, and 0.2 kg of tetraethyl titanate catalyst to another reaction vessel, stir and mix evenly, evacuate the reaction vessel and replace it with carbon dioxide gas, heat to 190℃ and stir for 10 h. After the reaction is completed, cool the reaction solution to 60℃ and remove the by-reaction products by vacuum distillation to obtain polybutylene terephthalate.

[0039] Mineralized cellulose was added to the above reaction vessel, followed by 0.4 kg of stannous octoate catalyst. Carbon dioxide was then introduced into the reaction vessel, and the temperature was raised to 250°C and stirred for 4 hours. 0.3 kg of antioxidant 1076 was added, and the mixture was stirred for 30 minutes to obtain CO2 mineralized reinforced bamboo fiber composite material 2.

[0040] Comparative Example 1

[0041] Add 55 kg of bamboo fiber with an average length of 15 mm, 0.03 kg of carbonic anhydrase, 5 kg of calcium chloride, and 550 kg of phosphate buffered saline (PBS) solution with a pH of 8.9 to a reaction vessel, and stir to mix evenly.

[0042] Introduce CO2 gas into the above reaction solution, control the system temperature at 10-40℃, add 10% Na2CO3 aqueous solution dropwise to adjust the pH of the reaction solution, control the pH of the reaction solution at 5-8, until the system no longer absorbs CO2 gas, consuming approximately 2 kg of Na2CO3 aqueous solution, and then stop the reaction.

[0043] The above reaction solution was centrifuged and filtered. The filtrate could be recycled. The filter residue was washed with deionized water until neutral. The washed filter residue was dried at 80°C to remove moisture. The moisture content was measured to be 0.2%, and mineralized cellulose was obtained.

[0044] Add 20 kg of terephthalic acid, 25 kg of 1,4-butanediol, and 0.5 kg of tetraethyl titanate catalyst to another reaction vessel, stir and mix evenly, evacuate the reaction vessel and replace it with argon gas, heat to 250℃ and stir for 6 hours. After the reaction is completed, cool the reaction solution to 80℃ and remove the by-reaction products by vacuum distillation to obtain polybutylene terephthalate.

[0045] Mineralized cellulose was added to the above reaction vessel, argon gas was introduced into the reaction vessel, the temperature was raised to 300℃ and stirred for 2 hours, 1.0 kg of antioxidant 168 was added, and the mixture was stirred for 30 minutes to obtain CO2 mineralized reinforced bamboo fiber composite material 3.

[0046] Comparative Example 2

[0047] 20 kg of terephthalic acid, 25 kg of 1,4-butanediol, and 0.5 kg of tetraethyl titanate catalyst were added to a reaction vessel and stirred until homogeneous. After the reaction vessel was evacuated, nitrogen gas was used to replace the evacuation gas. The temperature was raised to 250°C and stirred for 6 hours. After the reaction was completed, the reaction solution was cooled to 80°C and the by-products were removed by vacuum distillation to obtain polybutylene terephthalate.

[0048] Add 55 kg of bamboo fiber with an average length of 15 mm and 0.5 kg of calcium carbonate to the above reaction vessel, introduce nitrogen into the reaction vessel, heat to 300℃ and stir for 2 hours, add 0.3 kg of antioxidant 168, stir for 30 minutes to obtain bamboo fiber composite material 4.

[0049] Thermogravimetric analysis:

[0050] Samples: Take composite material 1 (mineralized + copolymerized) and composite material 3 (mineralized + blended), pulverize them, and vacuum dry them at 80°C to constant weight. Place about 5 mg of the sample in a sample crucible.

[0051] Instrument: TA2900;

[0052] Test: Heating rate is 10℃ / min, range is 125-700℃;

[0053] Results: See appendix for details. Figure 1 .

[0054] The degradation temperature of composite material 1 is 546℃, while that of composite material 3 is 404℃. Composite material 1 has better stability than composite material 3, indicating that the interfacial compatibility of composite material 1 is higher than that of composite material 3.

[0055] Tensile strength test:

[0056] Sample: Type 1A, dimensions 25mm×5mm×1mm, prepared by injection molding;

[0057] Instrument: Universal testing machine, uniaxial tensile test;

[0058] Test: The test rate was 3 mm / min, and the test temperature was 25℃. Each sample was tested three times, and the average value was taken. The results are shown in the table below.

[0059] Bending strength test:

[0060] Sample: 80mm×10mm×4mm in size, prepared by injection molding;

[0061] Instrument: Universal testing machine;

[0062] Test: Span 64mm, loading speed 2mm / min, results are shown in the table below.

[0063] Summary table of mechanical performance test results

[0064] sample Composite Material 1 Composite Material 2 Composite Material 3 Composite Material 4 Tensile strength (MPa) 97.86 93.45 76.14 66.49 Flexural strength MPa 89.54 86.82 72.76 55.98

[0065] The results in the table above show that the tensile strength of composite material 3 is 14.5% higher and the flexural strength is 30% higher than that of composite material 4. This indicates that when mineralized bamboo fiber obtained by mineralizing bamboo fiber with carbonic anhydrase is blended with PBT to form a composite material, it can enhance the bonding force between bamboo fiber and PBT, resulting in better structural uniformity and improved mechanical properties compared to unmineralized bamboo fiber. The tensile strength of composite material 1 is 28.5% higher and the flexural strength is 23.1% higher than that of composite material 3. This indicates that the mineralization of bamboo fiber with carbonic anhydrase, under the catalysis of a catalyst, further couples with PBT to form a mineralized bamboo fiber-PBT copolyester, which further improves the mechanical properties of the composite material, solves the problem of poor interfacial compatibility between bamboo fiber and PBT, and ultimately significantly improves the mechanical properties of the composite material, greatly expanding the application scenarios of bamboo fiber materials.

Claims

1. A method for preparing a carbonic anhydrase-catalyzed CO2 mineralization-reinforced bamboo fiber composite material, characterized in that, The composite material comprises, by weight, 15-20 parts of terephthalic acid, 16-25 parts of 1,4-butanediol, 0.2-1 parts of catalyst, 50-55 parts of bamboo fiber, 5-8 parts of calcium chloride, 0.01-0.03 parts of carbonic anhydrase, 1-2 parts of pH adjuster, and 0.3-1 parts of antioxidant. The catalyst is tetraethyl titanate and stannous octoate; The pH adjuster is one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and sodium carbonate aqueous solution; The antioxidant is one of antioxidant 1010, antioxidant 1076, and antioxidant 168; The method for preparing the composite material is characterized by comprising the following steps: S1: Add bamboo fiber, carbonic anhydrase, and calcium chloride to a phosphate buffered saline (PBS) solution with a pH of 6.2-8.9 according to the formula ratio, stir and mix evenly to obtain reaction solution 1, wherein the weight ratio of the buffered saline solution to bamboo fiber is 10:

1. S2: Pass CO2 gas into reaction solution 1 prepared in step S1, control the system temperature at 10-40℃, add pH adjuster solution dropwise, control the pH of the reaction solution at 5-8, until the system no longer absorbs CO2 gas, and obtain reaction solution 2. S3: Filter the reaction solution 2 prepared in step S2, wash the filter residue with deionized water until neutral, and dry the washed filter residue to remove moisture to obtain mineralized cellulose. S4: Mix terephthalic acid, 1,4-butanediol and tetraethyl titanate catalyst evenly according to the formula. Under the protection of an inert gas atmosphere, heat to 190-250℃ and stir for 6-10 hours. After the reaction is completed, cool the reaction solution to 60-80℃ and remove the by-reaction products by vacuum distillation to obtain polybutylene terephthalate. S5: Add the mineralized cellulose prepared in step S3 to the polybutylene terephthalate prepared in step S4, then add the catalyst stannous octoate, and stir the reaction at 250-300℃ for 2-4 hours in an inert gas stream. Add an antioxidant to the reaction system and stir for 30 minutes to obtain carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material.

2. The method for preparing carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material according to claim 1, characterized in that, In step S1, the length of the bamboo fiber is 8-17 mm.

3. The method for preparing carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material according to claim 1, characterized in that, In step S2, the mass concentration of the pH adjuster solution is 10-20%.

4. The method for preparing carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material according to claim 1, characterized in that, In step S3, the water content of the mineralized cellulose is not higher than 0.3%.

5. The method for preparing carbonic anhydrase-catalyzed CO2 mineralization reinforced bamboo fiber composite material according to claim 1, characterized in that, In steps S4 and S5, the inert gas is either nitrogen or argon.

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