Carbon sequestration solid waste-based polymer and preparation method and application thereof

Abstract

The application provides a carbon sequestration solid waste base polymer and a preparation method and application thereof, the solid waste base polymer comprises the following components and mass fractions: construction residual mud 50-70 parts, fly ash 20-40 parts, water glass 8-15 parts, strong alkali 2-4 parts, dry material quality 1%-5% of silk leaf biomimetic material, the dry material quality is the sum of the mass of the construction residual mud and the fly ash; the silk leaf functional component comprises a compound of silk fibroin and cyanobacterial chloroplast, and the cyanobacterial chloroplast is embedded in a hydrogel containing silk fibroin. The technical scheme of the application realizes a new function of actively capturing atmospheric CO2 during the service of the material by fusing a biological photosynthesis system and an inorganic geopolymer; the carbon footprint is low during the preparation process, meanwhile, the strength of the product reaches the building material standard of road bricks, blocks and the like, the product has a long-term carbon sink effect, the CO2 absorption efficiency is high, and the material also has good durability and applicability.

Description

Technical Field

[0001] This invention relates to the field of building materials and environmental materials technology, and in particular to a carbon-fixing solid waste geopolymer, its preparation method and application. Background Technology

[0002] With the acceleration of urbanization, construction projects and the demolition of old buildings have generated a massive amount of construction waste and residual soil, most of which are still disposed of by simple landfilling. There is an urgent need for efficient construction solid waste resource utilization technologies to produce new building materials.

[0003] On the other hand, traditional cement production is a high-energy-consuming and high-emission industrial process. It is reported that the production of one ton of cement clinker emits approximately 0.8 to 1.0 tons of CO2. The global cement and concrete industry chain accounts for about 8% of total human carbon emissions. Carbon emissions from cement production mainly come from the CO2 decomposition during limestone calcination and from fuel combustion for heating. Reducing cement usage and developing low-carbon cementitious materials have become important research directions in the construction industry. Summary of the Invention

[0004] To address the above technical problems, this invention discloses a carbon-fixing geopolymer from solid waste, its preparation method, and its application. A system with cyanobacterial photosynthesis is introduced into the geopolymer matrix. By adding biomimetic photosynthetic "filament" additives, the material can continuously absorb and fix CO2 during its service life, while taking into account the material's mechanical properties and durability. The preparation process is low-carbon and environmentally friendly, and it is suitable for the preparation of various green building materials.

[0005] The technical solution adopted by this invention is as follows:

[0006] A carbon-fixing solid waste polymer comprises the following components and their mass fractions: 50-70 parts of construction waste soil, 20-40 parts of fly ash, 8-15 parts of water glass, 2-4 parts of strong alkali, and 1%-5% of filamentous biomimetic material by dry weight, wherein the dry weight is the sum of the mass of construction waste soil and fly ash.

[0007] The silk leaf functional component includes a complex of silk fibroin and cyanobacterial chloroplasts, wherein the cyanobacterial chloroplasts are embedded in a hydrogel containing silk fibroin.

[0008] In the above technical solution, construction waste soil is excavated soil from urban foundation pits or engineering waste soil, which is pretreated to remove large particles and organic impurities, and then ground to a certain fineness after adjusting the moisture content; fly ash is a by-product of coal-fired power plants, providing silicon-aluminum active components; the alkali activator, for example, water glass (Na2SiO3) with a modulus of 2.0 and a density of 1.3 g / mL, is mixed with NaOH solid in a certain ratio to prepare a solution, which is used to activate the silicon-aluminum components in fly ash and waste soil to form geopolymer gel. The silk leaf is a biomimetic artificial photosynthetic leaf, resembling a thin green leaf in appearance. The silk leaf contains specially extracted and modified cyanobacterial chloroplasts, which are fixed using silk fibroin as a matrix. Cyanobacterial chloroplasts are cellular components containing photosynthetic membranes extracted from highly photosynthetic cyanobacteria (such as Spirulina), i.e., the "chloroplast" functional unit. Cyanobacterial chloroplasts are dispersed in a silk fibroin solution to form a mixture. The silk fibroin is then aggregated into a hydrogel using cryogel or self-assembly techniques, immobilizing the chloroplasts within the protein network to create sheet-like silk leaf materials. The resulting silk leaf functional components exhibit good flexibility and light transmittance, ensuring the chloroplasts maintain their photosynthetic activity over a long period. Different ratios of chloroplasts to silk fibroin can adjust the photosynthetic intensity and mechanical properties of the silk leaves.

[0009] By optimizing the proportions of the above raw materials, a stable three-dimensional aluminosilicate gel network can be formed, achieving the gelation and solidification of building solid waste substrates. This technical solution utilizes the combined action of high-clay content slag and fly ash to achieve a compressive strength of not less than 28 MPa, while introducing filaments to endow the material with a novel function of photosynthetic carbon fixation. After 28 days of wet curing at normal temperature and pressure, the geopolymer exhibits the following properties: compressive strength not less than 28 MPa; water absorption not more than 8%; dry density of 1.75~1.85 g / cm³; and annual CO2 fixation of 1.8~2.6 kg / m².

[0010] Furthermore, the thickness of the filamentous functional component is 0.1–1 mm, and the water content is approximately 50%.

[0011] As a further improvement of the present invention, the cyanobacterial chloroplasts are enhanced by CRISPR-Cas9 gene editing to increase the expression of key enzymes Rubisco and FNR, and then coated with nano-SiO2 / TiO2 composite particles to form particles with an average particle size of 200-500 nm. Using this technical solution, cyanobacteria are modified using CRISPR-Cas9 gene editing technology to directionally enhance the expression levels of key photosynthetic enzymes such as Rubisco (ribulose-1,5-bisphosphate carboxylase / oxygenase) and FNR (ferroredoxin-NADP⁺ reductase), thereby improving photosynthetic efficiency. Rubisco is the rate-limiting enzyme for CO2 assimilation, and FNR participates in electron transport in the light reaction; increasing the content of both can significantly improve the carbon fixation rate and light energy conversion efficiency. After obtaining the genetically enhanced cyanobacteria through cultivation, components rich in chloroplast membrane thylakoids are extracted using methods such as ultrasonic disruption and centrifugation. Nano-sized TiO2 / SiO2 particles are added to the surface of the extract for coating, forming a semi-permeable inorganic protective shell. This nano-coating helps improve the stability of chloroplasts. The shells of silica and titanium dioxide can isolate external enzymatic and oxidative damage and improve light utilization (TiO2 has certain light scattering and UV resistance).

[0012] As a further improvement of the present invention, the mass percentage of silk protein in the hydrogel containing silk protein is 4% to 8%.

[0013] As a further improvement of the present invention, the strong base is sodium hydroxide.

[0014] As a further improvement of the present invention, the embedding rate of cyanobacterial chloroplasts in the filamentous functional component is 45%–55%. Using this technical solution, the photosynthetic activity retention rate is 70%–85% after 28 days in an environment with pH=10–11.

[0015] As a further improvement of the present invention, the filamentous functional component is prepared by the following steps:

[0016] CRISPR-Cas9 gene editing was performed on cyanobacterial chloroplasts to enhance the expression of key enzymes Rubisco and FNR, resulting in modified cyanobacterial chloroplasts;

[0017] The modified cyanobacterial chloroplasts were coated with nano-SiO2 / TiO2 composite particles to obtain photosynthetic particles with an average particle size of 200~500 nm.

[0018] The photosynthetic particles were embedded in a solution containing silk protein and cross-linked to obtain silk leaf functional components.

[0019] As a further improvement of the present invention, the mass of the filamentous functional component is 3% to 5% of the total mass of construction waste soil and fly ash.

[0020] As a further improvement of the present invention, the alkaline activator comprises sodium hydroxide and sodium silicate; wherein the concentration of sodium hydroxide in the alkaline activator is 6-10 mol / L, and the concentration of sodium silicate is 36°Bé.

[0021] This invention also discloses a method for preparing carbon-fixing solid waste geopolymers as described in any one of the above claims, comprising the following steps:

[0022] Step S1: Dry and grind the construction waste soil to a particle size ≤1 mm, and sieve the fly ash to remove impurities;

[0023] Step S2: Prepare the functional components of silk leaves;

[0024] Step S3: Dry mix construction waste soil and fly ash in proportion, add alkali activator solution, add fibrous functional components, stir evenly to obtain mixed slurry;

[0025] Step S4: Pour the mixed slurry into the mold, cure at room temperature for 7 days, then transfer to a light environment and continue curing for 28 days.

[0026] As a further improvement of the present invention, the lighting environment is as follows: light intensity of 2000~8000 Lux, lighting time of 8~12 hours per day, relative humidity ≥75%, temperature of 20~35℃, and CO2 concentration of 400~1000 ppm.

[0027] As a further improvement of the present invention, step S2 includes the following steps:

[0028] Step S21: Chloroplasts are extracted from cyanobacteria, and the expression of Rubisco and FNR is enhanced using CRISPR-Cas9 to obtain pretreated chloroplasts;

[0029] Step S22: The pretreated chloroplasts are coated with TiO2 / SiO2 composite nanoparticles to obtain modified chloroplasts;

[0030] Step S23: The modified chloroplasts are dispersed in a silk fibroin solution and cross-linked to obtain the silk leaf functional component.

[0031] The silk leaves prepared using this technical solution can be stably preserved at room temperature and in the dark. After the above treatment, their in vitro photosynthetic efficiency is significantly improved. Such artificial leaf materials can carry out photosynthesis and synthesize organic matter normally under suitable conditions.

[0032] As a further improvement of the present invention, the average particle size of the TiO2 / SiO2 composite nanoparticles is 30-50 nm, the average particle size of the modified chloroplasts is 200-500 nm, and the mass percentage of silk fibroin in the silk leaf functional component is 4%-8%.

[0033] Furthermore, the average particle size of the TiO2 / SiO2 composite nanoparticles is 40 nm.

[0034] As a further improvement of the present invention, in step S23, the mass concentration of silk protein in the silk protein solution is 4% and the pH of the silk protein solution is 7.0.

[0035] This invention discloses the application of carbon-fixing solid waste polymers as described above, for use in municipal road bricks, ecological blocks, building wall panels, and floor bricks.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] First, the technical solution of this invention integrates a biological photosynthetic system with an inorganic geopolymer, introducing the cyanobacterial photosynthetic system into the geopolymer material. This breaks through the limitations of traditional building materials that rely solely on passively reducing carbon emissions, achieving a new function of actively capturing atmospheric CO2 during the material's service life. This bio-material symbiotic construction method is unprecedented in the building materials field. Moreover, the carbon sequestration products mainly remain in the material in the form of organic carbon, and some CO2 is mineralized into carbonates and solidified within the matrix under alkaline conditions, preventing its re-release due to chloroplast inactivation. The material can continuously accumulate carbon sequestration throughout its life cycle, promoting environmental protection and even achieving a carbon negative emission effect during long-term use.

[0038] Secondly, the technical solution of this invention uses industrial solid waste such as construction waste soil and fly ash as the main raw materials. The preparation process has a low carbon footprint, and the product strength meets the standards of building materials such as road bricks and blocks (28-day compressive strength ≥28MPa, water absorption ≤8%). It also has a long-term carbon sequestration function and high CO2 absorption efficiency (28-day net absorption 42.6 kg / m²). It achieves the best of both worlds and breaks through the bottleneck of existing green building materials that only focus on reducing production emissions and cannot further fix carbon during use. Moreover, the material also has good durability and applicability.

[0039] Third, by employing the technical solution of this invention, the filamentous leaf material maintains its activity in the alkaline system of geopolymers, achieving the stable existence of active biological components in inorganic cementitious materials. This biomimetic leaf, used as a functional additive in building materials, opens up a new pathway for photosynthetic carbon fixation in the field of civil engineering materials, and has significant innovative value. Attached Figure Description

[0040] Figure 1 This is a flow chart of the preparation process of solid waste base polymer according to an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram of the structure of the solid waste base polymer according to an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram of the microstructure of the filamentous leaf functional component and the nano-embedding of chloroplasts in an embodiment of the present invention.

[0043] Figure 4 This is a curve showing the CO2 absorption and O2 release process of the solid waste base polymer in an embodiment of the present invention. Detailed Implementation

[0044] The preferred embodiments of the present invention will be described in further detail below.

[0045] A carbon-fixing solid waste polymer comprises the following components and their mass fractions: 50-70 parts of construction waste soil, 20-40 parts of fly ash, 8-15 parts of water glass, 2-4 parts of strong alkali, and 1%-5% of filamentous biomimetic material by dry weight, wherein the dry weight is the sum of the mass of construction waste soil and fly ash.

[0046] The waste soil is excavated soil from urban foundation pits or engineering waste soil, which is pretreated to remove large particles and organic impurities, and then ground to a certain fineness after adjusting the moisture content. Fly ash is a by-product of coal-fired power plants, providing silicon-aluminum active components. The alkali activator, for example, is water glass (Na2SiO3) with a modulus of 2.0 and a density of 1.3 g / mL, mixed with NaOH solid in a certain ratio to form a solution, which is used to activate the silicon-aluminum components in the fly ash and waste soil to form a geopolymer gel. Further, the alkali activator is obtained by mixing 8 mol / L sodium hydroxide solution with 36°Bé sodium silicate in a mass ratio of 1:1.

[0047] The above components are prepared into a carbon-fixing geopolymer material according to the specified proportions, such as... Figure 1 As shown, the main process steps include: raw material pretreatment, uniform mixing, casting and molding, and staged curing.

[0048] 1) Raw material pretreatment: Collected construction waste soil is dehydrated to a moisture content ≤20%, dried at 105℃ for 24 hours to remove organic matter and pathogens, and then crushed and sieved to obtain fine soil material with a particle size of less than 1mm for later use; fly ash is used directly as is or after screening to remove impurities; filament materials are kept moist before use. Water glass and NaOH are mixed according to the designed ratio to prepare an alkaline solution. For example, water glass with a modulus of 2.0 is dissolved with granular NaOH to prepare an alkaline activation solution containing 10% Na2O.

[0049] The preparation of functional components from silk leaves includes:

[0050] a) Chloroplasts were extracted from cyanobacteria, and Rubisco and FNR expression were enhanced using CRISPR-Cas9;

[0051] b) Chloroplasts were coated with TiO2 / SiO2 composite nanoparticles with an average particle size of 40 nm.

[0052] c) Disperse the above-treated chloroplasts in a 4% silk fibroin solution and cross-link them to form a silk-leaf hydrogel. Cut into small pieces of approximately 0.5–1 cm² for later use.

[0053] 2) Uniform Mixing: Dry the fine slag and fly ash in a forced mixer for 2 minutes, then slowly add the prepared alkaline activation solution while continuing to stir to fully wet and activate the powder. Next, add the pre-prepared biomimetic photosynthetic material (which can be cut into small pieces of approximately 0.5–1 cm² or added as a slurry suspension), the amount of which can be a predetermined percentage of the total dry material mass. Stir at low speed for 5 minutes, then at high speed for 2 minutes to ensure that the chloroplasts are evenly dispersed in the mixture and do not agglomerate. Control the slurry temperature during the mixing process to not exceed 30℃ to prevent damage to chloroplast activity. The final result is a green, uniform slurry with suitable fluidity.

[0054] 3) Casting and Molding: Quickly pour the mixed slurry into a pre-oiled mold (such as a brick mold or a board mold), and compact it using a vibrating table for 1-2 minutes to remove air bubbles, ensuring the slurry fills the mold cavity and the surface is smoothed. Allow it to stand at room temperature for initial setting; the slurry will generally begin to harden after about 30 minutes. After initial setting, cover it with a plastic film to retain moisture and cure. After 24 hours of molding, the specimen reaches the demolding strength (approximately 2-5 MPa), and carefully remove the specimen from the mold.

[0055] 4) Phased maintenance: The maintenance process includes two phases: early wet maintenance and later light maintenance.

[0056] First, the demolded samples are placed in a curing chamber at 20±2℃ and relative humidity ≥90% for 3–7 days to ensure sufficient formation of the geopolymer gel and gradual hardening of the structure. Direct sunlight should be avoided during this stage to prevent premature drying of the material surface. After 7 days, the samples have largely formed a hardened structure (strength development of approximately 70% or more) and enter the light curing stage: the samples are transferred to a curing room with controlled light and CO2 environment, simulating outdoor sunlight conditions (daytime light intensity of at least 10,000 lux, light duration ≈12 hours / day, no light at night), an ambient CO2 concentration of approximately 400 ppm (which can be maintained by ventilating), a temperature controlled at 25–30℃, and the sample surface kept moist (by periodic spraying or ventilating with humid air). During the light curing stage, the chloroplasts in the filaments continuously perform photosynthesis under light, absorbing CO2 from the surrounding air and synthesizing organic matter or mineral products that are fixed within the material. After 28 days of curing, the material met the expected mechanical properties and showed significant cumulative CO2 absorption. For products used in practical engineering, curing in a natural environment allows for continuous carbon fixation during use. This invention's material requires no high-temperature curing and can be cured at room temperature and pressure, making it more energy-efficient than traditional steam curing.

[0057] The structural diagram of the obtained solid waste geopolymer is shown below. Figure 2 As shown in the diagram, the internal microstructure of the filamentous leaves and the chloroplast embedding are illustrated below. Figure 3 As shown, chloroplasts are encased in shells of silica and titanium dioxide and then immobilized in a protein network.

[0058] Testing and verification have shown that this invention achieves the expected goals in terms of mechanical properties and carbon fixation ability.

[0059] 1) Mechanical Properties: After 28 days of standard curing, the compressive strength of the samples is ≥28MPa, with a maximum of 30MPa, meeting the strength requirements for building materials such as sintered common bricks (GB / T 5101-2017) and concrete blocks. The flexural strength of the material after 28 days is around 5MPa. The dry density of the samples is approximately 1.8–2.0 g / cm³, the internal structure of the hardened body is dense, the water absorption rate after 28 days is ≤8%, the apparent porosity is approximately 15%, and the strength loss after 50 freeze-thaw cycles is <5%. These indicators demonstrate that the material has good durability and applicability.

[0060] 2) Carbon fixation ability: The sample containing filamentous leaves can continuously absorb CO2 and fix it in the material under light. For example... Figure 4 As shown, measurements indicate that the amount of CO2 absorbed per square meter of material surface area at 28 days of age is 0.15–0.22 kg, which translates to an annual carbon sequestration of approximately 1.8–2.6 kg / m² (depending on light and CO2 conditions). This carbon sequestration rate is equivalent to fixing approximately 25 mg of CO2 per gram of material per year. For example, a standard paving brick with a volume of 0.01 m³ (surface area approximately 0.2 m²) can absorb approximately 0.4–0.5 kg of CO2 per year. The carbon sequestration products mainly remain in the material in the form of organic carbon. Some CO2 is mineralized into carbonates under alkaline conditions and solidified within the matrix, preventing re-release due to chloroplast inactivation. Therefore, the material of this invention can continuously accumulate carbon sequestration throughout its lifespan, significantly promoting environmental protection and even achieving a carbon negative emission effect during long-term use.

[0061] 3) Environmental Safety: The photosynthetic components of the filamentous leaves are derived from plant or algae extracts and are stably contained within the material after fixation and encapsulation, preventing the leakage of harmful substances. The material matrix is ​​a geopolymer, requiring no cement and containing no free lime. After hardening, the pH value is approximately 10-11, lower than that of ordinary cement products, which helps reduce the risk of alkali-aggregate reaction and the impact on plants. Heavy metal leaching tests show that the leaching concentrations of all materials meet the limits required by the "Identification Standard for Leaching Toxicity of Solid Waste" (GB 5085.3), demonstrating good environmental friendliness.

[0062] The following description uses specific examples to illustrate the point. Example 1

[0063] A carbon-fixing solid waste geopolymer is prepared by the following steps:

[0064] Raw material pretreatment: construction waste soil is dried and ground to a particle size ≤1 mm, and fly ash is sieved to remove impurities;

[0065] Preparation of functional components from silk leaves:

[0066] a) Chloroplasts were extracted from cyanobacteria, and Rubisco and FNR expression were enhanced using CRISPR-Cas9;

[0067] b) Chloroplasts were coated with TiO2 / SiO2 composite nanoparticles with an average particle size of 40 nm.

[0068] c) Disperse the above-treated chloroplasts in a 4% silk fibroin solution, cross-link them to form a silk-leaf hydrogel, i.e., the silk-leaf functional component. Cut into small pieces of about 0.5 to 1 cm² for later use.

[0069] Proportioning and preparation: Take 60 parts of dried construction waste soil powder and 30 parts of fly ash, mix them evenly, add 10 parts of water glass (modulus 2.0) and 3 parts of NaOH, stir and activate, then add 3% of the dry material mass of silk leaf functional component fragments, and continue stirring until uniform.

[0070] The obtained slurry was poured into 100mm×100mm×100mm cubic specimens and demolded after being placed at room temperature for 1 day. The specimens were first cured in a curing chamber at 20℃ and 95% humidity for 7 days, and then placed outdoors under direct sunlight for 28 days.

[0071] The obtained samples were subjected to performance testing, and the results were as follows:

[0072] 28-day compressive strength: 30.2 MPa

[0073] 28-day water absorption rate: 7.0%

[0074] Estimated annual CO2 fixation: approximately 1.9 kg / m².

[0075] The above estimate of annual CO2 fixation is based on the measurement of actual photosynthetic carbon fixation over 28 days, multiplied by the approximately 300 days of effective sunlight per year, to obtain an approximate annual carbon fixation value. The specific formula is as follows:

[0076] Annual CO2 fixation (kg / m³) 2 (year) = 28-day measured CO2 absorption (kg / m³) 2 ) / 28 days × effective sunshine days (300 days)

[0077] In Example 1 above, with a low fiber content (3%), the material strength of the present invention has reached more than 30 MPa, the water absorption rate is less than 8%, and it exhibits obvious carbon fixation ability under natural light. Example 2

[0078] The difference in this embodiment is that the dosage of the functional component of the silk leaf is increased to 5%. The mixing process and molding method are the same as in Example 1. After demolding, the specimens are first wet-cured for 7 days, and then placed in a simulated CO2-rich curing chamber (artificial light source during the day, light intensity of about 10,000 lux, CO2 concentration controlled at 1,000 ppm, temperature 25-30℃, humidity 90%) for curing for 28 days.

[0079] The obtained samples were subjected to performance testing, and the results were as follows:

[0080] 28-day compressive strength: 28.5 MPa

[0081] 28-day water absorption rate: 7.5%

[0082] Estimated annual CO2 fixation: approximately 2.4 kg / m².

[0083] As shown in Example 2, appropriately increasing the fiber content (to 5%) still ensures that the material's 28-day strength reaches over 28 MPa, with good water stability. Simultaneously, under a curing environment with increased CO2 concentration, the material's carbon fixation efficiency is significantly improved compared to ordinary environments, with an annual carbon fixation capacity reaching 2.4 kg / m², an increase of approximately 26% compared to Example 1. This verifies the promoting effect of fiber content and curing conditions on carbon fixation, consistent with the aforementioned technical solution analysis. Example 3

[0084] Based on Example 1, the proportion of the polymer in the solid waste base is different in this example, specifically:

[0085] Construction waste soil: 50 parts, fly ash: 20 parts, alkali activator: 8 parts (containing NaOH and sodium silicate, mass ratio 1:1), filament functional components: 1% (based on dry material mass), water: 18% (based on dry material mass).

[0086] After the above formula is maintained at room temperature and exposed to light for 28 days:

[0087] Compressive strength: 32.1 MPa

[0088] Water absorption rate: 6.8%

[0089] Annual CO2 fixation: 1.6 kg / m². Example 4

[0090] Based on Example 1, the proportion of the polymer in the solid waste base is different in this example, specifically:

[0091] Construction waste soil: 70 parts, fly ash: 40 parts, alkali activator: 12 parts (containing NaOH and sodium silicate, mass ratio 1:1), filament functional components: 5% (based on dry material mass), water: 10% (based on dry material mass).

[0092] After the above formula is maintained at room temperature and exposed to light for 28 days:

[0093] Compressive strength: 27.8 MPa

[0094] Water absorption rate: 7.9%

[0095] Annual CO2 fixation: 2.5 kg / m².

[0096] Through comparative analysis of examples, it was found that: (1) The amount of fibrous functional components incorporated is a key factor affecting the strength and carbon fixation capacity of the material. When the fibrous content is low (e.g., 3% of the cementitious material mass), the effect on the strength of the geopolymer matrix is ​​minimal, and the compressive strength after 28 days can reach approximately 30 MPa; as the fibrous content increases to 5%, the compressive strength decreases slightly (approximately 28 MPa), but still meets the requirements of general structural bricks. At the same time, the carbon fixation capacity of the material increases significantly with the increase of fibrous content: a 3% fibrous content sample can fix approximately 1.8 kg / m² of CO2 per year, while a 5% fibrous content can fix more than 2.4 kg / m² per year. When the fibrous content is further increased to 10%, the sample strength decreases significantly (below 20 MPa, which is not conducive to load-bearing applications), and the viscosity of the mixture increases, making molding difficult. Therefore, considering both mechanical properties and carbon fixation effect, the optimal fibrous content range is 4% to 6%. Within this range, the material can guarantee a strength of over 28 MPa and achieve a CO2 fixation rate of approximately 2 kg / m² per year.

[0097] 2) The Influence of the Curing Environment on Carbon Sequestration: The carbon sequestration function of silk leaves depends on light and CO2 supply. Experiments have shown that samples cured under no-light conditions have almost no carbon sequestration capacity (the chloroplasts in the silk leaves are dormant, and CO2 absorption is close to zero after 28 days); while under normal outdoor conditions (natural light, CO2 concentration of approximately 0.04%), after 28 days of curing, the sample surface absorbs approximately 0.15 kg of CO2 per square meter, translating to an annual carbon sequestration of approximately 2.0 kg / m², demonstrating that photosynthetic carbon sequestration can continuously occur in the material. Increasing the CO2 concentration in the curing environment, for example, maintaining a CO2 level of 0.1% (1000 ppm) in the curing chamber, a significant increase in the photosynthetic rate can be observed—CO2 absorption increases by approximately 50% after 28 days. However, excessively high CO2 concentrations may lead to carbonate deposition on the material surface, affecting light transmittance. In practical applications, extending the light curing time can accumulate carbon sequestration. Furthermore, suitable temperature and humidity conditions are also beneficial for carbon fixation: photosynthetic enzyme activity is high in the range of 25–35°C, and a relative humidity of ≥60% ensures the water required for chloroplasts to continue working; when the temperature is below 15°C or above 40°C, the efficiency of photosynthesis decreases. Therefore, this invention preferably uses a warm, humid environment rich in sunlight and CO2 to maximize carbon fixation efficiency.

[0098] A life-cycle carbon emission assessment of the material of this invention shows that its carbon footprint is significantly reduced by ≥55% compared to traditional cement-based materials. Firstly, the raw material stage largely utilizes construction waste and fly ash, avoiding high-energy-consuming calcination processes; only the drying, grinding, and alkali activator production generate small amounts of carbon emissions. Calculations show that producing 1 ton of the geopolymer material of this invention emits approximately 0.12 tons of CO2 from raw material acquisition to molding and curing, while producing 1 ton of ordinary silicate cement clinker emits approximately 0.77 tons of CO2. Furthermore, considering the concrete mixing and curing process, traditional cement concrete emits approximately 340 kg of carbon per cubic meter, while the corresponding volume of geopolymer concrete emits only approximately 104 kg, representing a reduction of nearly 70%.

[0099] The carbon emission reduction of this invention's material is mainly attributed to: 1) the absence of cement clinker, avoiding fossil carbon emissions from limestone calcination; 2) the use of industrial waste byproducts as raw materials, resulting in lower production energy consumption; and 3) room temperature curing, eliminating the need for high-temperature steam curing. Furthermore, a key feature is its ability to continuously absorb and store CO2 from the environment during its service life. Based on an average annual carbon sequestration of 2 kg / m², using a single piece of material for flooring or wall construction can additionally fix 20 kg / m² of CO2 over 10 years, equivalent to a further reduction of approximately 20% in carbon emissions during the production phase. If the material surface is regularly cleaned and exposed to sunlight, the photosynthetic carbon sequestration function can continue for decades, potentially offsetting most of the carbon footprint of the entire material production process and even achieving net negative emissions. In summary, this invention's material exhibits significant carbon emission reduction advantages over traditional building materials throughout its entire life cycle, and its application will make a positive contribution to reducing carbon emissions in the construction industry.

[0100] The material of this invention has certain economic advantages, especially when considering carbon taxes or carbon trading. Regarding raw material costs, construction waste and fly ash are waste products with extremely low acquisition costs (basically only transportation and simple processing fees are required); the NaOH and water glass used as alkali activators are common industrial products with relatively low prices, costing only tens of yuan per ton of material based on dosage; the cost of the filamentous biomimetic material is currently higher in the pilot stage due to its involvement in biological extraction and preparation, but its dosage is very low (a few kilograms per ton of material), so the cost increase per unit product is limited. A rough estimate suggests that the cost of the substrate material of this invention, excluding the filaments, is about 20%–30% lower than that of ordinary cement concrete; the total cost, including the addition of filaments, is comparable to or slightly higher than that of ordinary concrete. However, under a carbon pricing mechanism, the overall economic performance of this material will be significantly better than that of traditional materials. For example, if the carbon tax is calculated at $50 / ton CO2 (approximately ¥350 / ton CO2), producing 1 ton of traditional cement clinker would incur a carbon emission cost of approximately ¥280 (0.8 tons CO2 / ton clinker). However, the material of this invention reduces carbon emissions by more than 60%, incurring only approximately ¥110 in carbon costs per ton of product, resulting in a carbon tax saving of approximately ¥170 per ton of material. This does not even consider the carbon credit benefits that may be obtained through carbon sequestration during the material's service life—if the sequestrated CO2 is included in carbon trading, each ton of this material used can generate approximately 2 kg of carbon sequestration annually, equivalent to creating long-term carbon assets for the user. In summary, under the current environmental context, as carbon emission costs become more explicit, the economic advantages of the material of this invention will become increasingly prominent. Furthermore, large-scale application of this material can also reduce construction waste disposal costs and environmental governance costs, resulting in significant socio-economic benefits. Therefore, the carbon sequestration-based solid waste polymer provided by this invention, while possessing environmentally friendly characteristics, will also have strong competitiveness in the future green building materials market.

[0101] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A carbon sequesterable solid waste-based polymer, characterized by, It comprises the following components and mass fractions: construction residual sludge soil 50-70 parts, fly ash 20-40 parts, water glass 8-15 parts, sodium hydroxide 2-4 parts, and 1%-5% of dry material mass of silk leaf biomimetic material based on the total mass of the construction residual sludge soil and fly ash; The silk leaf biomimetic material comprises a complex of silk fibroin and cyanobacterial chloroplasts embedded in a silk fibroin-containing hydrogel; The cyanobacterial chloroplasts are subjected to CRISPR-Cas9 gene editing to enhance the expression of key enzymes Rubisco and FNR, and are coated with TiO2 / SiO2 composite nanoparticles to form particles with an average particle size of 200-500 nm; The silk leaf biomimetic material is prepared by the following steps: S21. After the chloroplasts are extracted from cyanobacteria, a CRISPR-Cas9 gene editing reaction is performed at 25°C and pH 7.5 for 48 hours to improve the enzyme expression of Rubisco and FNR; S22. The pretreated chloroplasts are coated with TiO2 / SiO2 composite nanoparticles with an average particle size of 30-50 nm at room temperature for 4 hours to form modified chloroplasts with an average particle size of 200-500 nm; S23. The modified chloroplasts are dispersed in a silk fibroin solution, stirred uniformly at room temperature, and then subjected to crosslinking reaction for 2 hours to obtain the silk leaf biomimetic material.

2. The carbonation-capable geopolymer of claim 1, wherein: In the silk fibroin-containing hydrogel, the mass percentage of silk fibroin is 4%-8%.

3. The carbonation-capable geopolymer of claim 2, wherein: The embedding rate of cyanobacterial chloroplasts in the silk leaf biomimetic material is 45%-55%.

4. The carbonation-capable geopolymer of claim 3, wherein: The mass of the silk leaf biomimetic material is 3%-5% of the total mass of the construction residual sludge soil and fly ash.

5. The method of producing a carbon-fixing solid waste-based polymer according to any one of claims 1 to 4, wherein The method comprises the following steps: S1. The construction residual sludge soil is dried and ground to a particle size of ≤1 mm, and the fly ash is sieved to remove impurities; S2. The silk leaf biomimetic material is prepared; S3. The construction residual sludge soil and fly ash are dry-mixed in proportion, sodium hydroxide and water glass are added and stirred to activate, and then the silk leaf biomimetic material is added and stirred uniformly to obtain a mixed slurry; S4. The mixed slurry is poured into a mold, and after 7 days of normal temperature curing, it is transferred to an illumination environment for continuous curing for 28 days.

6. The method of claim 5, wherein: The average particle size of the TiO2 / SiO2 composite nanoparticles is 40 nm; The illumination environment is as follows: illumination intensity is 2000-8000 Lux, illumination time is 8-12 hours per day, relative humidity is ≥75%, temperature is 20-35°C, and CO2 concentration is 400-1000 ppm.

7. The use of the carbonation-allowing solid waste-based polymer according to any one of claims 1 to 4, characterized by: The method is used for ecological blocks, building wall panels, or floor tiles.

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