Method for mineralizing, reinforcing and protecting weathered sandstone cultural relics by using carbon sequestration bacteria

Abstract

The invention discloses a method for mineralizing, reinforcing and protecting weathered sandstone cultural relics through carbon sequestration bacteria, and belongs to the technical field of cultural relic protection and restoration. In order to solve the problems of residue of deliquescent anionic salt and generation of bad byproduct ammonia gas in the existing technology for reinforcing and protecting sandstone cultural relics by microbial mineralization, the reinforcing depth and strength are improved in a lower-carbon and higher-efficiency manner, and an aspartic acid chelated calcium liquid containing low-solubility active magnesium oxide is effectively permeated into weathered sandstone; the carbon capture and nucleation effects of the bacillus mucilaginosus with the carbon sequestration function are utilized, on one hand, carbon dioxide in air is captured and converted into carbonate needed by mineralization, on the other hand, carbonate in an ammonium carbonate solution which is easy to volatilize and decompose is locked and used for carbonate mineral crystallization, and meanwhile ammonium ions are inhibited from being converted into ammonia gas to overflow; calcium carbonate and basic magnesium carbonate are induced to be subjected to intercrystallization nucleation, and a high-strength cementation structure is formed in pores of the weathered sandstone and is used for permeating, reinforcing and protecting the weathered sandstone cultural relics.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for protecting and consolidating weathered sandstone cultural relics by carbon fixation bacteria mineralization, and belongs to the technical field of cultural relic protection and restoration. BACKGROUND

[0002] Sandstone cultural relics, especially grottoes and statues, are exposed to the natural environment for a long time. Due to the characteristics of sandstone material itself, compared with other common stone materials, sandstone has a large pore ratio, low strength, and weak weathering resistance, which leads to more prominent weathering damage threats to sandstone cultural relics. How to effectively consolidate and protect them is an urgent need in the field of cultural relic protection. For weathered sandstone cultural relics, it is necessary to use permeable consolidation and protection materials or surface sealing and protection materials for treatment, which requires that the consolidation and protection materials or sealing and protection materials and their processes can fully penetrate into the small pores or cracks of weathered sandstone, and at the same time, the strength and weather resistance of the consolidated and protected weathered sandstone can be greatly improved. The cementing material should also be compatible with the material quality of the cultural relics, so as to effectively improve the consolidation and protection effect of the weathered sandstone cultural relics.

[0003] Prior art scheme one

[0004] Existing stone cultural relic restoration and protection mostly uses inorganic materials such as barium oxide, high modulus potassium silicate, and hydraulic lime, or organic polymer materials such as epoxy resin and silicate for filling and restoration. Among them, inorganic materials have good aging resistance and are compatible with the material quality of stone cultural relics. Organic polymer materials have good permeability and hardening strength, and can fully penetrate into the small pores or cracks of weathered sandstone, effectively improving the strength of weathered sandstone cultural relics.

[0005] Defects of prior art scheme one

[0006] Inorganic consolidation and protection materials are mainly plastic solid materials or granular slurry materials, which have high viscosity and poor permeability, and are difficult to effectively penetrate into the small pores or cracks of weathered sandstone, resulting in poor permeability consolidation and protection effect for weathered sandstone. Organic polymer materials have certain toxicity and cannot meet the current green environmental protection requirements. Moreover, they are prone to aging and discoloration, and have poor weather resistance.

[0007] Prior art scheme two

[0008] Microbial mineralization repair technology is a new low-carbon and environmentally friendly cultural relic repair technology. Based on the urease reaction, the technology provides the mineralization bacteria with a substrate rich in calcium, magnesium ions and carbon source, and through the urease and nucleation of the mineralization bacteria, carbonate mineral crystals with cementation effect are precipitated to cement the stone cracks and weathered loose mineral particles, or a hard protective layer is formed on the surface of the cultural relic stone. The carbonate minerals induced by the technology are the same as or close to the natural mineral components contained in the cultural relic stone, and have excellent material compatibility with the cultural relic stone and good weather resistance of inorganic mineral materials; one prior art proposes to immerse the stone cultural relics in a mixed solution containing mineralization bacteria and calcium chloride or calcium nitrate tetrahydrate, so that a calcium carbonate protective film is generated on the surface of the stone to protect the interior of the stone from erosion; another prior art proposes to apply a mixed solution of mineralization bacteria, urea and calcium nitrate to the surface of the stone to generate a mineralization reaction and form a continuous and dense calcium carbonate protective hard layer on the surface of the stone, thereby achieving surface reinforcement and protection of the stone cultural relics.

[0009] Defects of the second prior art

[0010] The reaction substrate used in the existing microbial mineralization technology for reinforcing and protecting sandstone cultural relics usually contains high-concentration calcium chloride or calcium acetate. The chloride ions or acetate ions remaining in the weathered sandstone pores after the mineralization reaction are easy to form anions with strong hygroscopicity. Among them, chloride salts are generally considered to be potentially harmful salts in the protection of stone cultural relics. Under the repeated dry-wet changes and precipitation in outdoor environments, part of the anions with strong hygroscopicity gradually infiltrate and diffuse to the deeper part of the sandstone, and the other part repeatedly dissolves and crystallizes in the shallow layer of the sandstone, resulting in whitening or even crumbly appearance on the surface of the sandstone cultural relics, which not only affects the sensory of the reinforced sandstone cultural relics, but also poses a risk of long-term weather resistance degradation of the sandstone cultural relics. In addition, the existing microbial mineralization reinforcement and protection technology still has environmental problems due to the production of ammonia gas as a byproduct of urease mineralization. SUMMARY

[0011] Technical problem: how to avoid the use of chloride salts or other easily deliquescent anion salts that have potential risks to stone cultural relics in microbial mineralization technology, make full use of carbon dioxide in the air, greatly improve the infiltration and reinforcement depth and strength of weathered sandstone, inhibit the production of ammonia gas as a byproduct of microbial mineralization reaction, and achieve reinforcement and protection of weathered sandstone cultural relics in a more low-carbon way. This is the main technical problem solved by the present application.

[0012] Technical solution: The application provides a method for protecting and reinforcing weathered sandstone cultural relics by using carbon-fixing bacteria mineralization, and the method comprises the following steps: by means of the creative material formula and process, aspartic acid chelated calcium liquid containing low-solubility active magnesium oxide is effectively infiltrated into weathered sandstone, dried and crystallized in the sandstone pores, and then, the infiltrated Bacillus mucilaginosus and ammonium carbonate solution are sprayed, so that the method for obtaining carbonate by hydrolyzing urea in the existing mineralization reaction technology based on microorganism urease is broken through, the carbon capture and nucleation of Bacillus mucilaginosus with the function of carbon fixation are utilized, on one hand, carbon dioxide in the air is captured and converted into carbonate required for mineralization, on the other hand, the carbonate in the volatile and decomposable ammonium carbonate solution is locked for carbonate mineral crystallization, meanwhile, the ammonium ion is inhibited from being converted into ammonia gas and overflowed, and the calcium carbonate and basic magnesium carbonate are induced to alternately crystallize and nucleate, so that a high-strength cementation structure is formed in the pores of the weathered sandstone.

[0013] In order to achieve the purpose of the application, the application discloses a method for protecting and reinforcing weathered sandstone cultural relics by using carbon-fixing bacteria mineralization, and the method is characterized in that the method comprises the following steps: a. 0.1-0.2 g / L of polysorbate-80 is added into aspartic acid chelated calcium saturated solution, and ultrasonic oscillation is performed for 5-10 min to prepare a calcium source liquid; b. 5-15 parts of active magnesium oxide and 82-100 parts of the calcium source liquid are uniformly mixed to prepare a calcium-magnesium-based repair liquid; c. The calcium-magnesium-based repair liquid is repeatedly sprayed onto the surface of dry weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then, natural air drying is performed for 24-32 h; d. The aspartic acid chelated calcium saturated solution is repeatedly sprayed onto the surface of the weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then, natural air drying is performed for 24-48 h; e. 20-40 g / L of Bacillus mucilaginosus powder is added into 5 mol / L of ammonium carbonate solution, and stirring is uniformly performed, then the liquid is repeatedly sprayed onto the surface of the weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then, natural air drying is performed to complete the protection and reinforcement.

[0014] The beneficial effects of the present application are: (1) the problem of low solubility of active magnesium oxide leading to difficulty in infiltrating weathered sandstone pores is overcome, and the calcium-magnesium-based repair liquid can deeply penetrate the weathered sandstone, greatly improving the reinforcement depth and strength of the weathered sandstone; (2) the inorganic mineral microstructure of the generated basic magnesium carbonate and calcium carbonate intercrystallization greatly improves the weather resistance of the reinforced sandstone, overcoming the poor bonding weather resistance of organic reinforcing materials, and the reinforcement product is more close to natural rock in mineral composition and sensory; (3) the defects of residual of undesirable by-products in the existing microbial mineralization reinforcement technology are overcome, the biological carbonation of Bacillus mucilaginosus efficiently converts carbon dioxide in the atmosphere into carbonate minerals with reinforcement effect, while greatly reducing the release amount of ammonia gas in the microbial mineralization reaction, so that there is no residual of salts such as chlorides which have potential harm to cultural relics in the reinforced sandstone cultural relics, and there is also no residual of high-hygroscopic salts such as acetates which have a significant impact on the sensory of open-air sandstone cultural relics, which is more environmentally friendly and safe. DETAILED DESCRIPTION

[0015] Example 1

[0016] In this example, a method for mineralization reinforcement and protection of weathered sandstone cultural relics by using carbon-fixing bacteria is used to reinforce and protect a strongly weathered sandstone grotto, and the material of the cultural relics is strongly weathered calcareous cemented quartz sandstone with a weathering layer depth of 15 cm. The method steps are as follows: a. 0.1 g / L of polysorbate-80 is added to the aspartic acid chelated calcium saturated solution, and ultrasonic oscillation is performed for 5 min to prepare a calcium source liquid; b. 15 parts of active magnesium oxide and 100 parts of the calcium source liquid are mixed uniformly to prepare a calcium-magnesium-based repair liquid; c. The calcium-magnesium-based repair liquid is repeatedly sprayed onto the surface of the dry weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then naturally air-dried for 32 h; d. The aspartic acid chelated calcium saturated solution is repeatedly sprayed onto the surface of the weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then naturally air-dried for 48 h; e. 40 g / L of Bacillus mucilaginosus powder is added to a 5 mol / L ammonium carbonate solution, stirred uniformly, and repeatedly sprayed onto the surface of the weathered sandstone until the liquid cannot continue to infiltrate from the surface of the sandstone, and then naturally air-dried to complete the reinforcement and protection.

[0017] Example 2

[0018] In this example, a method for mineralization reinforcement and protection of weathered sandstone cultural relics by using carbon-fixing bacteria is used to reinforce and protect a moderately weathered sandstone statue, and the material of the cultural relics is moderately weathered calcareous cemented feldspar sandstone with a weathering layer depth of 7 cm. The method steps are as follows: a. Poly sorbate-80 was mixed into aspartic acid chelated calcium saturated solution at a dosage of 0.15 g / L, and a calcium source solution was prepared by ultrasonic oscillation for 8 min; b. 10 parts of active magnesium oxide and 91 parts of the calcium source solution were mixed uniformly to prepare a calcium-magnesium-based repair solution; c. The calcium-magnesium-based repair solution was repeatedly sprayed onto the surface of the dry weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried for 28 h; d. The aspartic acid chelated calcium saturated solution was repeatedly sprayed onto the surface of the weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried for 36 h; e. Bacillus mucilaginosus powder was mixed into an ammonium carbonate solution with a concentration of 5 mol / L at a dosage of 30 g / L, stirred uniformly, and repeatedly sprayed onto the surface of the weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried to complete the reinforcement and protection.

[0019] Example 3

[0020] In this example, a method for reinforcing and protecting slightly weathered sandstone historical relics by carbon-fixing bacteria mineralization was used to reinforce and protect slightly weathered sandstone historical relics. The material of the historical relics was slightly weathered siliceous cemented quartz sandstone, and the weathering layer depth was 2.5 cm. The method steps were as follows: a. Poly sorbate-80 was mixed into aspartic acid chelated calcium saturated solution at a dosage of 0.2 g / L, and a calcium source solution was prepared by ultrasonic oscillation for 10 min; b. 5 parts of active magnesium oxide and 82 parts of the calcium source solution were mixed uniformly to prepare a calcium-magnesium-based repair solution; c. The calcium-magnesium-based repair solution was repeatedly sprayed onto the surface of the dry weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried for 24 h; d. The aspartic acid chelated calcium saturated solution was repeatedly sprayed onto the surface of the weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried for 24 h; e. Bacillus mucilaginosus powder was mixed into an ammonium carbonate solution with a concentration of 5 mol / L at a dosage of 20 g / L, stirred uniformly, and repeatedly sprayed onto the surface of the weathered sandstone until the liquid could no longer infiltrate the surface of the sandstone, and then naturally air-dried to complete the reinforcement and protection.

Claims

1. A method for reinforcing and protecting weathered sandstone cultural relics by mineralization using carbon-fixing bacteria, characterized in that The steps of this method are as follows: a. Add polysorbate 80 to a saturated solution of calcium aspartate chelate at a dosage of 0.1 to 0.2 g / L and ultrasonically vibrate for 5 to 10 minutes to prepare a calcium source solution. b. Mix 5-15 parts of active magnesium oxide and 82-100 parts of calcium source solution by mass to prepare a calcium-magnesium-based repair solution; c. Repeatedly spray the calcium-magnesium-based repair liquid onto the dry weathered sandstone surface until the liquid can no longer penetrate the sandstone surface, and then allow it to air dry for 24 to 32 hours; d. Repeatedly spray the saturated solution of aspartic acid chelated calcium onto the surface of the weathered sandstone until the liquid can no longer penetrate the sandstone surface, and then allow it to air dry for 24 to 48 hours; e. Add 20-40 g / L of Bacillus subtilis powder to a 5 mol / L ammonium carbonate solution, stir evenly, and spray repeatedly onto the surface of the weathered sandstone until the liquid can no longer penetrate the sandstone surface. Then allow it to dry naturally to complete the reinforcement and protection.