Hollow fiber mediated biological concrete carbon fixation fiber, preparation method and concrete

Abstract

The invention relates to the cross technical field of building materials and microorganism mineralization, and discloses a hollow fiber mediated biological concrete carbon fixation fiber, a preparation method and concrete.The carbon fixation fiber comprises a fiber carrier providing a transportation path and a diffusion channel for CO2 and carbon fixation microorganisms loaded on the fiber carrier, and the solid carbon fibers are applied to concrete as reinforcing fibers. According to the invention, carbon-fixing microorganisms are loaded on the surface of a fiber carrier with a hollow structure, so that carbon-fixing fibers with a stable microorganism-carrier composite system are formed; the carbon fixation fiber is applied to concrete, a transportation path and a diffusion channel are provided for CO2 in a concrete matrix through hollow mediation, and through directional mineralization of carbon fixation microorganisms on an interface where the reinforced fiber and the concrete are replaced, the carbon fixation amount is increased, meanwhile, the interface bonding force is enhanced, and the low-carbon concrete with the high CO2 storage capacity and the excellent mechanical property is prepared. And a new material and a new process are provided for a carbon neutralization target in the building industry.

Description

Technical Field

[0001] The present invention relates to the technical field of intersection between building materials and microbial mineralization, and in particular to hollow fiber-mediated bioconcrete solid carbon fibers, a preparation method and concrete. Background Art

[0002] The climate crisis, triggered by surging global carbon emissions, poses a severe threat to the ecological environment. The construction industry, a key source of carbon emissions, sees its core material, concrete, see its annual production continue to climb, projected to exceed 5.5 billion tons by 2025. Carbonate decomposition and fuel combustion during cement production contribute approximately 8% of global CO2 emissions (2.8 billion tons annually). Furthermore, overexploitation of river sand resources is exacerbating ecological pressures. Against this backdrop, the combination of seawater sand concrete (SWSSC) and fiber-reinforced polymer (FRP) bars has emerged as a strategic solution for coastal projects. However, the inherently high alkaline environment of concrete (pH > 12.5) can easily degrade the FRP bar-concrete interface, restricting its application.

[0003] The International Energy Agency (IEA) points out that even with a transition to renewable energy, carbon capture, utilization, and storage (CCUS) technologies will still need to process 100 million to 1 billion tons of CO2 annually by 2050 to achieve net-zero emissions. Concrete carbonation curing technology injects CO2 into the matrix and mineralizes it into stable carbonates (such as CaCO3 and MgCO3). This not only permanently fixes carbon but also significantly reduces the pore fluid pH to 8-10, completely eliminating the risk of alkaline corrosion of FRP rebar. This technology also optimizes the microstructure of concrete, improving its mechanical properties and durability, making it a key path in the transition to low-carbon building materials.

[0004] However, current carbonation curing technologies face two major bottlenecks: First, the dense structure of concrete restricts CO2 diffusion, resulting in a carbon sequestration efficiency typically less than 25%; second, the technology generally relies on high-pressure or high-concentration CO2 sources, making the carbon capture-compression-transport chain energy-intensive and incompatible with the principle of carbon neutrality. Consequently, biocatalytic carbon sequestration has attracted attention due to its mild reaction conditions. However, direct bacterial incorporation methods face key obstacles: bioenzymes are easily inactivated in highly alkaline environments (pH > 12.5), and the CO2 transfer efficiency within concrete is limited. Summary of the Invention

[0005] In view of the fact that the physical limitations of CO2 transmission to the interior of existing concrete carbonization and carbon fixation technologies are still difficult to overcome, and the defects of the separation of carbon fixation and enhancement performance are still difficult to overcome, this application proposes a hollow fiber-mediated microbial concrete carbon fiber, in which the fiber carrier provides a transport path and diffusion channel for CO2, significantly reducing the CO2 diffusion resistance; the fiber carrier itself serves as the CO2 transport path, improving the CO2 transmission efficiency; the carbon-fixing microorganisms loaded on the fiber carrier are directionally mineralized at the fiber-matrix interface, strengthening the interfacial bonding, and solving the problem of the separation of carbon fixation and enhancement performance. The specific solution is as follows: Hollow fiber-mediated bioconcrete carbon fiber, including: a fiber carrier that provides a transport path and a diffusion channel for CO2, and carbon-fixing microorganisms loaded on the fiber carrier; The fiber carrier is a hollow structure.

[0006] Preferably, the fiber carrier is a natural hollow fiber and / or a synthetic hollow fiber.

[0007] Preferably, the carbon-fixing microorganisms have the characteristics of accelerating the hydration of CO2 to form carbonate ions, and dissolving the alkaline substances in the concrete matrix by secreting organic acids to form carbonate precipitates; The carbon-fixing microorganism is Bacillus subtilis.

[0008] A method for preparing hollow fiber-mediated bioconcrete-solidified carbon fibers, the method being applied to the preparation of hollow fiber-mediated bioconcrete-solidified carbon fibers, the method comprising: S1, preparing hollow fiber yarns using natural hollow fibers and / or synthetic hollow fibers; S2, pre-treating the hollow fiber filaments, and sequentially performing alkali modification, impurity removal, and drying on the pre-treated hollow fiber filaments to obtain a fiber carrier, wherein the fiber carrier has the function of improving the antistatic and flame retardancy of the hollow fiber filaments while maintaining the original mechanical properties of the hollow fiber filaments; S3, performing surface treatment on the fiber carrier to increase its roughness; S4, soaking the fiber carrier in a culture solution of carbon-fixing microorganisms to obtain hollow fiber-mediated bioconcrete-fixed carbon fibers; The fiber volume content of the fiber carrier is 0.5 kg / m 3 ~1.5 kg / m 3 ; The concentration of the carbon fixation microbial culture solution is 2×10 3 CFU / m~2×10 9 CFU / ml, soak at constant temperature for 12h.

[0009] Preferably, the alkali treatment in S2 is performed by soaking in an organic amine solution at room temperature for 12 hours; The organic amine solution is an ethanolamine solution.

[0010] Preferably, the pretreatment process of the hollow fiber in S2 includes soaking in an alkaline solution and then washing with clean water; the impurity removal process in S2 includes washing with an alcohol solution and then repeatedly washing with clean water.

[0011] Preferably, the alkaline solution is 80% sodium hydroxide solution, soaked at 80°C for 24 hours; The alcohol solution is a 50% anhydrous ethanol solution.

[0012] The network is embedded in the matrix to form a rapid CO2 transport pathway, achieving deep regional gradient mineralization.

[0013] In response to existing concrete carbonization and carbon sequestration technologies, this application provides a hollow fiber-mediated bioconcrete, which uses hollow fiber-mediated bioconcrete solid carbon fibers as a reinforcement matrix embedded in the concrete matrix to prepare carbon sequestration concrete that has both carbon sequestration and improved mechanical properties. The specific solution is as follows: A hollow fiber-mediated bioconcrete, the carbon-fixing concrete comprising: a concrete matrix and reinforcing fibers embedded in the concrete matrix; The reinforcing fibers are the hollow fiber-mediated bioconcrete solid carbon fibers; The hollow fiber-mediated bioconcrete carbon fiber provides a transport path and diffusion channel for CO2 in the concrete matrix through hollow mediation, and provides a living environment for the loaded carbon-fixing microorganisms. On the other hand, the loaded carbon-fixing microorganisms are directionally mineralized at the interface between the reinforced fiber and the concrete, thereby increasing the carbon fixation amount and strengthening the interface bonding.

[0014] Preferably, the concrete matrix is ​​formed by mixing steel slag, cementitious material, sand and gravel aggregate and water.

[0015] Preferably, the carbonization and carbon fixation method of the carbon-fixing concrete includes: S1, preparation of concrete matrix material; S2, adding the hollow fiber-mediated bioconcrete solid carbon fiber into the concrete matrix material, stirring to uniformly disperse it in the concrete matrix material, and pouring it into the corresponding mold for solidification; S3, place the solidified concrete in a carbonation curing box at 50% CO2, 50% RH, and 25°C and cure for 7d, 14d, and 28d respectively.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The fiber carrier in this application is a hollow structure that provides a diffusion channel for CO2. The fiber carrier itself serves as a CO2 transport path, which provides a living environment for carbon-fixing microorganisms to solve the physical limitations of CO2 internal transmission in the prior art. On the one hand, carbon-fixing microorganisms accelerate the hydration of CO2 to form carbonate ions, and on the other hand, they secrete organic acids to dissolve Ca in steel slag. 2+ / Mg 2+ , forming carbonate precipitation; to achieve directional mineralization at the fiber-matrix interface, strengthen interface bonding, and solve the problem of carbon fixation-enhancement performance separation; Among them, natural hollow fibers are preferably sisal fibers, and synthetic hollow fibers are preferably polypropylene fibers. Since the cavity diameter of sisal / polypropylene fibers is 3 to 4 orders of magnitude larger than the capillary pores of concrete, the CO2 diffusion resistance is significantly reduced; and the fiber network is embedded in the matrix to form a rapid CO2 transport path, achieving deep regional gradient mineralization; When preparing hollow fiber-mediated bioconcrete carbon fibers, the hollow fibers are first alkali-modified. The surfaces of the hollow fibers of natural fibers (sisal fibers) and synthetic fibers (polypropylene fibers) are subjected to high-temperature alkali etching to enhance their surface roughness, thereby increasing the pore size of the PP fiber surface. The modified hollow fibers are then loaded with carbon-fixing microorganisms. While providing a living environment for fluorocarbon microorganisms, the hollow fiber structure serves as a high-speed CO2 diffusion channel, accelerating the carbonization reaction and increasing the amount of carbon fixed. At the same time, the bacteria are directed to mineralize at the fiber-matrix interface, strengthening interfacial bonding, thereby promoting the transmission of CO2 during carbonization curing and increasing the degree of carbonization. The fibers are then immersed in a bacterial solution of carbon-fixing microorganisms so that the carbon-fixing microorganisms are loaded on the surface of the fiber carrier, thereby preparing hollow fiber-mediated bioconcrete carbon fibers.

[0017] The present invention incorporates hollow fiber-mediated bioconcrete solid carbon fibers into carbonization-cured concrete as reinforced fibers for concrete. The hollow fiber lumen provides a channel for the transmission of CO2, thereby increasing the amount of carbon fixed and the strength of carbonization-cured sea sand concrete. The carbon-fixing microorganisms loaded on the fiber carrier are specifically Bacillus mucilaginosus. When added to carbonization-cured sea sand concrete, the mineralization effect of the bacteria increases the amount of carbon fixed and improves the density of the concrete, thereby improving the mechanical properties of the concrete. For example, Bacillus mucilaginosus can dually catalyze the mineralization of CO2: on the one hand, it accelerates the hydration of CO2 to generate carbonate ions, and on the other hand, it secretes organic acids to dissolve Ca in steel slag. 2+ / Mg 2+ , forming carbonate precipitation; the matrix of concrete is made of a mixture of steel slag, cementitious materials, sand and gravel aggregates, and water. Steel slag is used as an auxiliary cementitious material to replace cement. Its calcium-magnesium-rich minerals (CaO, MgO) provide a highly active ion source for the carbonation reaction, while realizing the resource utilization of solid waste.

[0018] In this application, specimens with bacteria and hollow fibers incorporated alone, as well as fiber-loaded hollow fibers, are prepared to test the degree of carbonization and mechanical properties at different carbonization ages. Saturated calcium hydroxide solution is used as a control for curing to analyze the improvement effect of fiber-loaded bacteria under carbonization, thereby preparing carbon-fixing concrete with both carbon sequestration and improved mechanical properties.

[0019] This invention not only solves the problem of limited carbonization depth of CO2 in concrete, but also combines modified hollow fibers and Bacillus subtilis through innovative theories and methods to achieve carbonization degree and carbon fixation while improving the mechanical properties of carbonation-cured concrete. It has important theoretical significance and practical application value. This technology provides a scalable low-carbon material solution for the construction, marine engineering and CCUS industries, combining structural safety and carbon neutrality benefits, and is in line with the needs of global sustainable development strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the hollow fiber bacteria-loaded enhanced carbonization and carbon fixation method of the present invention; Figure 2 Schematic diagram of fiber processing, specimen forming and curing in an embodiment of the present invention; Figure 3 The microstructure diagram of the hollow fiber, fiber carrier, and fiber carrier loaded with microorganisms prepared in the embodiments of the present invention; Figure 4 Schematic diagram of carbonization degree of concrete at different ages in an embodiment of the present invention; Figure 5 Schematic diagram of the influence of different factors on the compressive strength at different ages (7d, 14d, 28d) in the embodiment of the present invention; Figure 6 Schematic diagram of the influence of different factors on 28d flexural strength in an embodiment of the present invention; Figure 7 This is a graph showing the XRD test results of 28d microscopic properties under different factors in the embodiments of the present invention. Figure 8 This is the TG test result diagram of the 28d microscopic properties under different factors of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example 1: The hollow fiber-mediated bioconcrete carbon fiber fixation includes: a fiber carrier that provides a transport path and a diffusion channel for CO2, and carbon-fixing microorganisms loaded on the fiber carrier.

[0023] The fiber support is a hollow structure, wherein the fiber support is a hollow fiber filament prepared from natural hollow fibers and / or synthetic hollow fibers.

[0024] The carbon-fixing microorganisms have the characteristics of accelerating the hydration of CO2 to form carbonate ions, and dissolving the alkaline substances in the concrete matrix by secreting organic acids to form carbonate precipitation; The carbon-fixing microorganism is Bacillus subtilis.

[0025] Example 2: A method for preparing hollow fiber-mediated bioconcrete solid carbon fibers, the preparation method comprising: S1, preparing hollow fiber yarns using natural hollow fibers and / or synthetic hollow fibers, wherein natural hollow fibers include but are not limited to sisal fibers, and synthetic hollow fibers include but are not limited to polypropylene fibers (PP fibers); the hollow fiber yarns in this embodiment are hollow sisal fibers and hollow PP fibers mixed together with a length of 15 mm; S2, the length of S1 is 15 mm, the volume dosage is 0.5 kg / m 3 The mixed hollow sisal fiber and hollow PP fiber are pretreated (specifically, the hollow fiber is placed in an 80% sodium hydroxide cleaning solution, soaked at 80°C for 24 hours, and then rinsed with clean water), the pretreated hollow fiber is sequentially subjected to an alkali modification treatment (immersed in an organic amine solution for 12 hours to alkali-modify the hollow fiber), first washed twice with a 50% anhydrous ethanol solution, and finally repeatedly rinsed with clean water to remove impurities, and then naturally dried to obtain a fiber carrier, wherein the fiber carrier has the ability to improve the antistatic and flame retardancy of the hollow fiber while maintaining the original mechanical properties of the hollow fiber; S3, performing surface treatment on the fiber support (specifically, high-temperature alkali etching) to increase its roughness; S4, the modified hollow fiber was placed in the carbon fixation microbial culture medium (i.e., the concentration was 2×10 3 CFU / m3 of Bacillus mucilaginosus concentrate), and the container was placed in a constant temperature box and soaked for 12 hours to obtain hollow fiber-mediated bioconcrete solid carbon fibers, that is, sisal fibers and PP fibers loaded with Bacillus mucilaginosus.

[0026] Example 3: A method for preparing hollow fiber-mediated bioconcrete solid carbon fibers, the preparation method comprising: S1, preparing hollow fiber filaments using natural hollow fibers and / or synthetic hollow fibers, wherein the natural hollow fibers include but are not limited to sisal fibers, and the synthetic hollow fibers include but are not limited to polypropylene fibers (PP fibers); in this embodiment, the hollow fiber filaments are mixed hollow sisal fibers and hollow PP fibers with a length of 15 mm; S2, the length of S1 is 15 mm, the volume dosage is 1.0 kg / m 3 The mixed hollow sisal fiber and hollow PP fiber are pretreated (specifically, the hollow fiber is placed in an 80% sodium hydroxide cleaning solution, soaked at 80°C for 24 hours, and then rinsed with clean water), the pretreated hollow fiber is sequentially subjected to an alkali modification treatment (immersed in an organic amine solution for 12 hours to alkali-modify the hollow fiber), first washed twice with a 50% anhydrous ethanol solution, and finally repeatedly rinsed with clean water to remove impurities, and then naturally dried to obtain a fiber carrier, wherein the fiber carrier has the ability to improve the antistatic and flame retardancy of the hollow fiber while maintaining the original mechanical properties of the hollow fiber; S3, performing surface treatment on the fiber support (specifically, high-temperature alkali etching) to increase its roughness; S4, the modified hollow fiber was placed in the carbon fixation microbial culture medium (i.e., the concentration was 2×10 6 CFU / ml of Bacillus subtilis concentrate), the container was placed in a constant temperature box and soaked for 12 hours to obtain hollow fiber-mediated bioconcrete solid carbon fibers, that is, sisal fibers and PP fibers loaded with Bacillus subtilis.

[0027] Example 4: A method for preparing hollow fiber-mediated bioconcrete solid carbon fibers, the preparation method comprising: S1, preparing hollow fiber filaments using natural hollow fibers and / or synthetic hollow fibers, wherein the natural hollow fibers include but are not limited to sisal fibers, and the synthetic hollow fibers include but are not limited to polypropylene fibers (PP fibers); in this embodiment, the hollow fiber filaments are mixed hollow sisal fibers and hollow PP fibers with a length of 15 mm; S2, the length of S1 is 15 mm, the volume dosage is 1.5 kg / m 3The mixed hollow sisal fiber and hollow PP fiber are pretreated (specifically, the hollow fiber is placed in an 80% sodium hydroxide cleaning solution, soaked at 80°C for 24 hours, and then rinsed with clean water), the pretreated hollow fiber is sequentially subjected to an alkali modification treatment (immersed in an organic amine solution for 12 hours to alkali-modify the hollow fiber), first washed twice with a 50% anhydrous ethanol solution, and finally repeatedly rinsed with clean water to remove impurities, and then naturally dried to obtain a fiber carrier, wherein the fiber carrier has the ability to improve the antistatic and flame retardancy of the hollow fiber while maintaining the original mechanical properties of the hollow fiber; S3, performing surface treatment on the fiber support (specifically, high-temperature alkali etching) to increase its roughness; S4, the modified hollow fiber was placed in the carbon fixation microbial culture medium (i.e., the concentration was 2×10 9 CFU / ml of Bacillus subtilis concentrate), the container was placed in a constant temperature box and soaked for 12 hours to obtain hollow fiber-mediated bioconcrete solid carbon fibers, that is, sisal fibers and PP fibers loaded with Bacillus subtilis.

[0028] Example 5: A hollow fiber-mediated biocarbon sequestration concrete, comprising: a concrete matrix and reinforcing fibers embedded in the concrete matrix; The reinforcing fibers are the hollow fiber-mediated bioconcrete-solidified carbon fibers prepared in Examples 2 to 4; The hollow fiber-mediated bioconcrete carbon fiber provides a transport path and diffusion channel for CO2 in the concrete matrix through hollow mediation, and provides a living environment for the loaded carbon-fixing microorganisms. On the other hand, the loaded carbon-fixing microorganisms are directionally mineralized at the interface between the reinforced fiber and the concrete, thereby increasing the carbon fixation amount and strengthening the interface bonding.

[0029] The concrete matrix is ​​formed by mixing steel slag, cementitious materials, sand and gravel aggregates and water.

[0030] Example 6: A method for preparing hollow fiber-mediated biocarbon sequestration concrete, specifically comprising: In Examples 2 to 4, the concentration of Bacillus mucilaginosus was 2×10 3 CFU / ml, 2×10 6 CFU / ml and 2×10 9 CFU / ml; the volume dosage of sisal fiber and PP fiber were 0.5 kg / m 3 , 1 kg / m 3 , 1.5 kg / m 3; Other factors remain unchanged, the prepared sisal fibers and PP fibers loaded with Bacillus mucilaginosus are respectively added to the same concrete matrix, and corresponding carbon-fixing concrete specimens are prepared respectively. The specific preparation steps of the carbon-fixing concrete specimens are as follows: (1) Pour the cementitious material and various sand and gravel aggregates into a mixer and dry mix them; (2) Mix the water (concentrated bacterial solution) evenly and pour it into the blender until the mixture reaches the target fluidity; (3) Add the sisal fiber and PP fiber loaded with Bacillus subtilis prepared in Examples 2 to 4 into the blender in small amounts and in multiple times to uniformly disperse them; (4) Stirring for 2 minutes, quickly stirring and then pouring out immediately, respectively completing the three concrete specimens corresponding to Examples 2 to 4, and completing the preparation process of the concrete specimens.

[0031] The molding sizes of the concrete specimens are 100mm×100mm×100mm cubic specimens and 100mm×100mm×400mm prism specimens.

[0032] Example 7: like Figure 1 As shown, the three concrete specimens prepared in Example 6 were demoulded and placed in 50% CO 2 The concrete specimens were carbonized and cured in a carbonization curing box at 50% RH and 25℃ for 7d, 14d and 28d respectively; some mix concrete specimens were placed in calcium hydroxide solution and cured for 28d as a control.

[0033] The following comparative examples analyze and illustrate the effects of different fiber carriers, different concentrations of added bacterial solution, different volume additions of sisal fiber, and different volume additions of PP fiber on the carbonization degree, mechanical properties, and microscopic properties of the prepared sea sand concrete specimens.

[0034] Comparative Example 1: This comparative example analyzes the effects of different fiber carriers on the carbonization degree, mechanical properties and microscopic tests of sea sand concrete. In this comparative example, cement, steel slag, sea sand, 5mm~20mm crushed stone, water and water reducer are used as raw materials to prepare concrete matrix materials. The fiber content is 1.5 kg / m 3 Different fiber carriers were placed in a bacterial concentration of 2×10 6 After being immersed in concentrated bacterial liquid with a CFU / ml, hollow fibers mediated by bio-concrete solidified carbon fibers with different fiber carriers were obtained, and the hollow fibers mediated by bio-concrete solidified carbon fibers with different fiber carriers were respectively incorporated into concrete matrix materials to prepare sea sand concrete specimens with hollow fibers mediated by bio-concrete solidified carbon fibers with different fiber carriers. The raw material ratios of the sea sand concrete specimens with different fiber carriers are shown in Table 1: Table 1 Raw material ratios of sea sand concrete specimens with different fiber carriers

[0035] The preparation process of sea sand concrete specimens of hollow fiber-mediated bioconcrete with carbon fibers fixed to the concrete surface with different fiber carriers is as follows: (1) Pour the cementitious material and aggregate into a mixer and dry mix for 2 minutes; (2) Mix the water reducer and water evenly, pour them into a mixer, and wet mix for 3 minutes until the mixture reaches the target fluidity; (3) Finally, add the bacterial solution, fiber or fiber-loaded bacteria into the blender and stir for 1 min. Then, load the fibers into molds of 100 mm × 100 mm × 100 mm and 100 mm × 100 mm × 400 mm to complete the preparation process.

[0036] After 24 h of molding, the molds were removed and the prepared 100 mm × 100 mm × 100 mm compression test pieces and 100 mm × 100 mm × 400 mm flexural test pieces were placed in 50% CO 2 The specimens were cured in a carbonization curing box at 50% RH and 25°C for 7, 14, and 28 days. The specimens cured for 7, 14, and 28 days were then subjected to compressive strength tests and carbonization degree tests. The specimens cured for 28 days were subjected to flexural strength tests and microscopic property tests (X-ray diffraction analysis and thermogravimetric analysis). The specimens cured in water for 28 days were subjected to compressive strength tests.

[0037] The carbonization degree of the split specimens cured for 28 days was tested using a 1% phenolphthalein solution. The carbonization degree was determined by calculating the ratio of the carbonized area of ​​the colorless region to the total cross-sectional area.

[0038] The carbonization degree, mechanical properties and microscopic test results were analyzed in a coordinated manner, and the microstructure of fiber-loaded bacteria was shown as follows: Figure 3 As shown in the figure, the change law of carbonization degree is as follows Figure 4 As shown in the figure, the mechanical properties change law is as follows Figure 5 (a) and Figure 6 As shown, the microscopic properties are Figure 7 (a) and 8(a), the carbonization results of hollow fiber-mediated bioconcrete with different fiber carriers are shown in Table 2.

[0039] Table 2 Carbonization results of hollow fiber-mediated bioconcrete with different fiber carriers

[0040] Analysis of the carbonization degree test results shows that under carbonization curing conditions, the carbonization degree of hollow fiber-mediated bioconcrete prepared with different fiber carriers is improved to varying degrees compared with the control group at different ages. When carbonization curing reaches 28 days, the carbonization degree of sisal fiber-loaded bacteria and PP fiber-loaded bacteria is increased by 26.62% and 33.33% respectively compared with the control group.

[0041] Analysis of the mechanical properties test results shows that under carbonization curing conditions, the compressive strength of hollow fiber-mediated bioconcrete prepared with different fiber carriers is improved to varying degrees compared with the control group at different ages. When carbonization curing reaches 28 days, the compressive strength of sisal fiber-loaded bacteria and PP fiber-loaded bacteria are increased by 25.88% and 30.21% respectively compared with the control group; the flexural strength is increased by 12.83% and 17.69% respectively.

[0042] Analysis of microscopic performance test results reveals that in the control group without BM, the main component of the concrete paste is Ca(OH)2, with a small amount of CaCO3 formed from the XRD patterns. In the SB and PB groups, Ca(OH)2 is almost completely converted to CaCO3; the CaCO3 diffraction peak in the PB group is the highest of all groups. Furthermore, the study indicates that at temperatures between 600°C and 800°C, corresponding to the decomposition of calcium carbonate, the carbon fixation rate in the control group without bacteria and fiber addition was 17.37%, while that in the SB and PB groups was 23.31% and 24.48%, respectively, representing increases of 5.94% and 7.11% compared to the control group. Carbonic anhydrase secreted by Bacillus mucilaginosus accelerates CO2 dissolution and promotes early CaCO3 precipitation (MICP). The CaCO3 precipitate fills microcracks and pores, increasing density and, consequently, improving mechanical properties. Furthermore, the hollow fibers provide a relatively stable space for BM to survive and function. The hollow fiber lumen provides CO2 for the MICP generated by the BM. Its unique pore structure also directs sufficient CO2 to diffuse into microbial-rich areas, optimizing the spatial distribution of the carbonization reaction. The hollow fiber and enzymes work together to synergistically promote carbonization.

[0043] Comparative Example 2: This comparative example investigates the effects of adding different concentrations of bacterial solution on the carbonization, mechanical properties and micro-properties of carbonized sea sand concrete. 3 CFU / ml, 2×10 6 CFU / ml, 2×10 9 CFU / ml, and was added into the concrete matrix at 10% of water. The specific proportion is shown in Table 3, and the other parameters are consistent with those in Comparative Example 1.

[0044] Table 3 Mix ratio of sea sand concrete prepared with different concentrations of bacterial solution

[0045] The macro properties of sea sand concrete prepared with different proportions were tested. The macro properties test results are shown in Table 4. The change law of carbonization degree is as follows: Figure 4 As shown in the figure, the mechanical properties change law is as follows Figure 5 (b) and Figure 6 As shown, the microscopic properties are Figure 7 (b) and 8(b).

[0046] Table 4 Carbonation degree of sea sand concrete with different bacterial concentrations

[0047] From the carbonization degree of sea sand concrete with different bacterial concentrations in Table 4, it can be seen that under carbonization curing conditions, the carbonization degree of concrete mixed with bacteria is improved to varying degrees compared with the control group at different ages. When carbonization curing reaches 28 days, the bacterial solution concentration is 2×10 6 The carbonization degree increased the most at CFU / ml, which was 30.0% higher than that of the control group.

[0048] Analysis of the mechanical properties test results of sea sand concrete with different bacterial concentrations shows that under carbonization curing conditions, the mechanical properties of carbonization-cured sea sand concrete first increase and then decrease at three different bacterial concentrations; and the mechanical properties of sea sand concrete with carbonization curing at a bacterial concentration of 2×10 6 The compressive strength and flexural strength reached their maximum values ​​when the carbonization curing reached 50 CFU / ml. After carbonization curing for 28 days, the compressive strength and flexural strength of group B2 were increased by 19.96% and 8.85% respectively compared with group C.

[0049] The microscopic performance test results of sea sand concrete with different bacterial concentrations were analyzed. From the XRD spectrum, it can be found that the diffraction peak intensity of CaCO3 in the carbonized concrete samples with BM addition was significantly improved, while the diffraction peak intensity of Ca(OH)2 was weakened, indicating that the minerals were gradually carbonized with the addition of BM. The diffraction peak of Ca(OH)2 in group B2 was the weakest, indicating that the carbonization efficiency was the highest at this concentration. Carbonic anhydrase (CA) produced by BM catalyzes the generation of a large amount of carbonate ions, as shown in formulas (1) and (2). Ca(OH)2 reacts with carbonate ions and is completely converted into CaCO3, so the CaCO3 peak of the carbonized specimens with bacterial addition is much higher than that of the control concrete. At the same time, according to the thermogravimetric results, the carbon fixation rates of the carbonized specimens with different addition amounts of B1, B2, and B3 were 19.4%, 21.9%, and 20.4%, respectively, which were 2.1%, 4.6%, and 3.1% higher than those of the control, respectively. With the increase of BM concentration, the Ca in the environment increased. 2+ 、 and H +The concentration of bacteria increases accordingly. High concentrations of bacteria can regulate the growth characteristics of nucleation sites and promote the precipitation of carbonates by increasing the concentration of catalytic enzymes. When bacteria over-aggregate, nutrients (such as urea and Ca 2+ ) is rapidly depleted, causing the later metabolism to stagnate. At the same time, the local supersaturation state will trigger disordered crystallization of CaCO3, thereby weakening the bonding force between the interfaces and reducing the compressive strength.

[0050] (1) (2) Comparative Example 3: This example explores the effects of different volumetric dosages of sisal fiber on the carbonization, mechanical properties, and microscopic properties of carbonization-cured sea sand concrete.

[0051] The raw material composition in this comparative example does not include the PP fiber and bacterial solution described in comparative example 1, and the amount of sisal fiber used is 0.5 kg / m 3 , 1.0kg / m 3 , 1.5kg / m 3 , the other parameters are the same as those in Comparative Example 1.

[0052] The test ratio of this embodiment is shown in Table 5, the macro performance test results are shown in Table 6, and the microstructure of the sisal fiber after modification is shown in Table 6. Figure 3 As shown in the figure, the change law of carbonization degree is as follows Figure 4 As shown in the figure, the mechanical properties change law is as follows Figure 5 (c) and Figure 6 As shown, the microscopic properties are Figure 7 (c) and 8(c).

[0053] Table 5 Mix proportion of sea sand concrete with different sisal fiber content

[0054] Table 6 Carbonization results of sea sand concrete with different sisal fiber content

[0055] Analysis of the carbonization degree test results of sea sand concrete with different sisal fiber content shows that under carbonization curing conditions, the carbonization degree of concrete with sisal fiber added is higher than that of the control group at different ages. When carbonization curing reaches 28 days, the carbonization degree of concrete with sisal fiber content of 1.0 kg / m 3 The carbonization degree was the greatest when the reaction mixture was heated, increasing by 33.33% compared with the control group.

[0056] The mechanical properties test results of sea sand concrete with different sisal fiber content were analyzed. It can be found that under carbonization curing conditions, the mechanical properties of carbonization cured sea sand concrete increased first and then decreased under the three fiber content. When the sisal fiber content was 1.0 kg / m 3 The compressive and flexural strengths reached their maximum values ​​at 28 days of carbonization curing. At 28 days of carbonization curing, the compressive and flexural strengths of group S2 increased by 16.35% and 9.96%, respectively, compared to those of group C. The decline in mechanical properties at 28 days may be due to the decomposition of natural fibers at 28 days, which increases the concrete's pore structure.

[0057] The microscopic performance test results of sea sand concrete with different sisal fiber content were analyzed. From the XRD spectrum, it can be found that the diffraction peak intensity of CaCO3 in the carbonized concrete samples with sisal fiber added is significantly improved, while the diffraction peak intensity of Ca(OH)2 is weakened. Figure 2 The microstructure of the sisal fibers after alkali modification shows that the surface of the fibers is distributed with lumen openings. The lumen openings provide a permeation channel for CO2 during the carbonization curing process. CO2 enters the concrete through the fiber lumen, thereby promoting the increase of carbonization degree. The diffraction peak of CaCO3 in the S2 group is the strongest, indicating that the fiber content is 1.0 kg / m 3 At the same time, according to the thermogravimetric results, it can be found that the carbon fixation rates of the samples with different addition amounts of S1, S2, and S3 are 19.12%, 21.4%, and 20.5%, respectively, which are 1.8%, 4.1%, and 3.2% higher than those of the control group.

[0058] Comparative Example 4: This comparative example analyzes the carbonization performance, mechanical properties and micro properties of sea sand concrete with different PP fiber content. The difference from comparative example 1 is that this comparative example does not contain sisal fiber and carbon fixation bacteria solution in comparative example 1. The other parameters are consistent with those in Example 1. 3 , 1.0 kg / m 3 , 1.5 kg / m 3 The effect of adding different amounts of PP fiber on the carbonization of carbonization-cured sea sand concrete was investigated. The proportions of the components in this comparative example are shown in Table 7, with the dosages of 0.5 kg / m 3 , 1.0 kg / m 3 , 1.5 kg / m 3 The macro performance test results of sea sand concrete with PP fiber are shown in Table 8. The microstructure of PP fiber after modification is as follows: Figure 3 As shown in the figure, the change law of carbonization degree is as follows Figure 4 As shown in the figure, the mechanical properties change law is as follows Figure 5 (d) and Figure 6 As shown, the microscopic properties are Figure 7 (d) and 8(d).

[0059] Table 7 Mix ratio of sea sand concrete with different PP fiber content

[0060] Table 8 Carbonization results of sea sand concrete with different PP fiber content

[0061] The carbonization degree test results of sea sand concrete with different PP fiber content were analyzed. It can be found that under carbonization curing conditions, the carbonization degree of concrete with PP fiber added is higher than that of the control group at different ages. Similar to sisal fiber, when carbonization curing reaches 28 days, the PP fiber content is 1.0 kg / m 3 The carbonization degree increased the most when the mixture was heated, which was 36.6% higher than that of the control group.

[0062] Analysis of the mechanical properties test results of sea sand concrete with different PP fiber content shows that under carbonization curing conditions, the mechanical properties of carbonization cured sea sand concrete first increase and then decrease under different fiber content; when the sisal fiber content is 1.0 kg / m 3 The compressive and flexural strengths reached their maximum values ​​at 28 days of carbonization curing. At 28 days of carbonization curing, the compressive and flexural strengths of group P2 increased by 17.50% and 10.40%, respectively, compared to those of group C. The decline in mechanical properties at 28 days may be due to excessive fiber content, resulting in uneven mixing and the formation of clusters. These clusters acted as stress concentration points, triggering preferential crack propagation.

[0063] The microscopic performance test results of sea sand concrete with different sisal fiber content were analyzed. From the XRD spectrum, it can be found that in the carbonized concrete sample with sisal fiber added, the diffraction peak intensity of CaCO3 is significantly improved, while the diffraction peak intensity of Ca(OH)2 is weakened, similar to the results of sisal fiber. Figure 2 The microstructure of the modified PP fiber shows that the pore size of the surface of the modified PP fiber increases, which promotes the transmission of CO2 during the carbonization curing process, thereby promoting the improvement of the carbonization degree. The diffraction peak of CaCO3 in the P2 group is the strongest, indicating that the fiber content is 1.0 kg / m 3 At the same time, according to the thermogravimetric results, it can be found that the carbon fixation rates of the samples with different addition amounts of P1, P2, and P3 are 19.63%, 21.58%, and 20.53%, respectively, which are 2.26%, 4.21%, and 3.16% higher than those of the control group.

[0064] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. Hollow fiber-mediated bioconcrete solid carbon fiber, characterized in that, include: A fiber carrier that provides a transport path and diffusion channel for CO2, and carbon-fixing microorganisms loaded on the fiber carrier; The fiber carrier is a hollow structure.

2. The hollow fiber-mediated bioconcrete carbon fiber according to claim 1, characterized in that: The fiber carrier is a natural hollow fiber and / or a synthetic hollow fiber.

3. The hollow fiber-mediated bioconcrete carbon fiber according to claim 1, characterized in that: The carbon-fixing microorganisms have the characteristics of accelerating the hydration of CO2 to form carbonate ions, and dissolving the alkaline substances in the concrete matrix by secreting organic acids to form carbonate precipitation; The carbon-fixing microorganism is Bacillus subtilis.

4. A method for preparing hollow fiber-mediated bioconcrete solid carbon fibers, characterized in that: The preparation method is applied to the preparation of hollow fiber-mediated bioconcrete solid carbon fibers according to any one of claims 1 to 3, and the preparation method comprises: S1, preparing hollow fiber yarns using natural hollow fibers and / or synthetic hollow fibers; S2, pre-treating the hollow fiber filaments, and sequentially performing alkali modification, impurity removal, and drying on the pre-treated hollow fiber filaments to obtain a fiber carrier, wherein the fiber carrier has the function of improving the antistatic and flame retardancy of the hollow fiber filaments while maintaining the original mechanical properties of the hollow fiber filaments; S3, performing surface treatment on the fiber carrier to increase its roughness; S4, soaking the fiber carrier in a culture solution of carbon-fixing microorganisms to obtain hollow fiber-mediated bioconcrete-fixed carbon fibers; The fiber volume content of the fiber carrier is 0.5 kg / m 3 ~1.5 kg / m 3 ; The concentration of the carbon fixation microbial culture solution is 2×10 3 CFU / m~2×10 9 CFU / ml, soak at constant temperature for 12h.

5. The method for preparing hollow fiber-mediated bioconcrete solid carbon fibers according to claim 4, characterized in that: The alkali treatment in S2 is carried out by soaking in an organic amine solution at room temperature for 12 h; The organic amine solution is an ethanolamine solution.

6. The method for preparing hollow fiber-mediated bioconcrete solid carbon fibers according to claim 4, characterized in that: The pretreatment process of the hollow fiber in S2 includes soaking in an alkaline solution and then washing with clean water; the impurity removal process in S2 includes washing with an alcohol solution and then repeatedly washing with clean water.

7. The method for preparing hollow fiber-mediated bioconcrete solid carbon fibers according to claim 6, characterized in that: The alkaline solution is 80% sodium hydroxide solution, soaked at 80°C for 24 hours; The alcohol solution is a 50% anhydrous ethanol solution.

8. A hollow fiber-mediated bioconcrete, characterized in that: The carbon sequestration concrete comprises: a concrete matrix and reinforcing fibers embedded in the concrete matrix; The reinforcing fiber is the hollow fiber-mediated bioconcrete solid carbon fiber according to any one of claims 1 to 3; The hollow fiber-mediated bioconcrete carbon fiber provides a transport path and diffusion channel for CO2 in the concrete matrix through hollow mediation, and provides a living environment for the loaded carbon-fixing microorganisms. On the other hand, the loaded carbon-fixing microorganisms are directionally mineralized at the interface between the reinforced fiber and the concrete, thereby increasing the carbon fixation amount and strengthening the interface bonding.

9. The hollow fiber-mediated bioconcrete according to claim 8, characterized in that: The concrete matrix is ​​formed by mixing steel slag, cementitious materials, sand and gravel aggregates and water.

10. The hollow fiber-mediated bioconcrete according to claim 8, characterized in that: The carbonization and carbon fixation method of the carbon-fixing concrete comprises: S1, preparation of concrete matrix material; S2, adding the hollow fiber-mediated bioconcrete solid carbon fiber into the concrete matrix material, stirring to uniformly disperse it in the concrete matrix material, and pouring it into the corresponding mold for solidification; S3, place the solidified concrete in a carbonation curing box at 50% CO2, 50% RH, and 25°C and cure for 7d, 14d, and 28d respectively.

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