Method for reinforcing red sandstone stone cultural relics in Sichuan and Chongqing regions based on induced mineralization of soybean extracted urease

Abstract

The invention belongs to the technical field of stone cultural relic surface reinforcement, and particularly discloses a method for reinforcing red sandstone stone cultural relics in Sichuan and Chongqing regions based on soybean extracted urease induced mineralization, which comprises the following steps: S1, extraction of soybean urease: taking fresh soybeans, drying and crushing, adding deionized water, stirring, refrigerating, filtering, centrifuging, taking supernatant liquid, and drying to obtain soybean urease; obtaining a soybean urease solution; s2, preparing a cementing liquid: dissolving calcium lignosulphonate in deionized water, adding urea, and fully and uniformly stirring to obtain the cementing liquid; s3, preparing and using the repairing material: mixing the soybean urease solution and the cementing liquid, and applying the mixture to the surface of the cultural relic in batches by adopting a micro-mist spraying method. According to the method provided by the invention, calcium lignosulphonate is adopted to prepare the cementing liquid, the cementing liquid and the soybean urease solution jointly act on the rock surface to induce calcium carbonate deposition, a mineralization protection layer is formed, the weathering resistance is improved, the structure is reinforced, good water and air permeability is kept, and excessive mineralization is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of surface reinforcement of stone cultural relics, and in particular relates to a method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization-inducing effect of urease extracted from soybean. Background Art

[0002] Red sandstone is a sedimentary rock, mainly red, dark red or brownish red. It is named for its rich iron oxides and is widely used in cultural relics carving. The Cretaceous-Jurassic red sandstone is widely distributed in Sichuan and Chongqing, my country. It is mainly characterized by weak cementation and high porosity (18%-25%). Under the continuous action of the subtropical monsoon climate (annual average precipitation 1200-1600 mm, humidity>80%), the rock cement is easily dissolved (permeability coefficient 1×10 -4 cm / s), resulting in surface peeling and structural instability (average annual weathering depth of 0.5-1.2 mm), which is not conducive to the preservation of local stone cultural relics.

[0003] Based on the above factors, the reinforcement materials of stone cultural relics are not only required to have good adhesion, stability and durability, but also to be weather-resistant and breathable, and to preserve the original color of the cultural relics as much as possible. Traditional stone cultural relic reinforcement materials have problems such as poor compatibility, short-term repair effects and potential secondary damage, which can hardly meet the long-term protection needs of stone cultural relics. With the renewal of cultural relic protection concepts, bio-induced mineralization technology has become a new choice for the reinforcement of stone cultural relics. Among them, urease-induced calcium carbonate precipitation technology (EICP) is favored by researchers because it can utilize the calcium carbonate protective layer formed by natural biomineralization to achieve good compatibility between the cultural relic body and the protective layer at the chemical and physical levels, achieving the dual effects of anti-weathering and structural reinforcement.

[0004] However, the existing EICP technology uses calcium chloride as the calcium source, which can easily cause excessive mineralization of the rock surface, produce a permeability inhibition effect, and have a whitening color difference, making it difficult to meet the protection needs of red sandstone cultural relics. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for reinforcing red sandstone stone cultural relics in the Sichuan and Chongqing areas based on the mineralization induced by urease extracted from soybeans. The binder is prepared by calcium lignin sulfonate, and the binder is sprayed on the surface of the red sandstone in batches with a soybean urease solution to quickly induce calcium carbonate deposition to form a mineralized protective layer. The method can significantly improve the weathering resistance of the red sandstone and repair microcracks while maintaining good water permeability and air permeability, avoiding excessive mineralization and penetration inhibition caused by traditional calcium chloride sources. At the same time, the color of calcium lignin sulfonate is similar to that of the original red sandstone rock, and the color difference is small after reinforcement, which does not affect the appearance of the cultural relics, maintains the authenticity of the cultural relics, and effectively solves the problems in the background technology.

[0006] The present invention is achieved through the following technical solutions: A method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybeans, comprising the following steps: S1. Extraction of soybean urease: fresh soybeans are dried and crushed to make them evenly dispersed to obtain soybean fine powder; the soybean fine powder is added to deionized water, stirred on a magnetic stirrer, and refrigerated to obtain a soybean mixed solution; the soybean mixed solution is filtered and centrifuged, and the supernatant is taken to obtain a soybean urease solution; S2. Preparation of a binder: using calcium lignin sulfonate as a calcium source and urea as a urea source, dissolving calcium lignin sulfonate in deionized water, adding urea, and stirring well to obtain a binder; S3, preparation and use of repair materials: the soybean urease solution and the cementing liquid are mixed, and applied to the surface of the cultural relics in batches by a micro-mist spraying method; after spraying, the cultural relics are solidified and maintained; The concentration of calcium lignin sulfonate in the binder is 1-10 mol / L, the concentration of urea is 1-10 mol / L, and the molar concentration ratio of calcium lignin sulfonate to urea is 1:1.

[0007] A further improvement of the present invention is: In S1, the drying temperature is 40-45°C and the drying time is 23-25h.

[0008] Furthermore, in S1, the drying temperature is 40° C. and the drying time is 24 h.

[0009] A further improvement of the present invention is: In S1, the stirring time is 20-40 min, the refrigeration temperature is 4-5° C., and the refrigeration time is 24-28 h.

[0010] Furthermore, in S1, the stirring time is 30 min, the refrigeration temperature is 4° C., and the refrigeration time is 24 h.

[0011] A further improvement of the present invention is: In S1, the centrifugal speed is 4000-5000 r / min, and the centrifugal time is 30-40 min.

[0012] Furthermore, in S1, the centrifugal speed is 4000 r / min and the centrifugal time is 30 min.

[0013] A further improvement of the present invention is: In S2, the calcium lignin sulfonate is made from waste paper as raw material. Beneficial Effects

[0014] Compared with the prior art, the present invention has the following obvious advantages: 1. The method provided by the present invention adopts calcium lignin sulfonate to prepare a binder, which is mixed with a soybean urease solution and then sprayed on the surface of red sandstone in batches by a micro-mist spraying method, so as to quickly induce calcium carbonate deposition and form a mineralized protective layer, which can significantly improve the weathering resistance of red sandstone and repair microcracks while maintaining good water permeability and air permeability, avoiding excessive mineralization and penetration inhibition caused by traditional calcium chloride sources; at the same time, the color of calcium lignin sulfonate is similar to that of the original red sandstone rock, and the color difference is small after reinforcement, which does not affect the appearance of the cultural relics and maintains the authenticity of the cultural relics.

[0015] 2. The present invention provides a method for extracting urease from soybeans, which has a wide source, low cost, and a simple extraction process, and can effectively improve the operability of cultural relics reinforcement projects. Field experiments have shown that soybean urease has strong weather resistance and can adapt to the high humidity and rainfall climate conditions in the Sichuan and Chongqing regions, and can maintain a high catalytic activity and reinforcement effect in the natural environment, providing a more operational and stable technical solution for cultural relics reinforcement.

[0016] 3. The method provided by the present invention is based on the bionic principle and uses calcium carbonate as a reinforcement product. Because it is a natural cementing material in red sandstone and its strength is lower than that of the cultural relic itself, it can act as a sacrificial layer when it is damaged, avoiding additional damage to the main body of the cultural relic, thereby achieving a more gentle and controllable protection effect.

[0017] 4. The raw materials used in the present invention have low pollution. Soybean urease can be degraded in the natural environment without residual harmful substances, which not only ensures the reinforcement effect but also has good environmental friendliness, providing a more sustainable green solution for cultural relics protection; calcium lignin sulfonate is made from waste paper as raw material, which effectively saves costs and realizes the recycling of waste paper. Its weeding and insecticidal properties can also effectively reduce biological diseases on the surface of cultural relics, delay the weathering process, and improve the stability of long-term preservation of cultural relics. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the effect of restoring cultural relics by the method provided by the present invention; Figure 2 The color difference comparison diagram of the red sandstone samples before reinforcement and after reinforcement of Example 1 and Comparative Example 1; Figure 3 It is a line chart comparing the compressive strength of red sandstone samples before reinforcement and after reinforcement of Example 1 and Comparative Example 1; Figure 4 The contact angle comparison diagram of the red sandstone sample before reinforcement and after reinforcement in Example 1; Figure 5 The microstructure comparison diagram of the red sandstone sample before reinforcement and after reinforcement of Example 1 and Comparative Example 1; Figure 6 This is a bar graph showing the change in soybean urease activity under the on-site conditions of Example 2 within one year. DETAILED DESCRIPTION

[0019] The present invention is described in detail below in conjunction with embodiments.

[0020] Example 1: Red sandstone reinforcement test (1) Extraction of soybean urease: fresh soybeans were dried at 40°C for 24 hours, and then crushed to make them evenly dispersed to obtain soybean fine powder; the soybean fine powder was added to deionized water, stirred on a magnetic stirrer for 30 minutes, and refrigerated at 4°C for 24 hours to obtain a soybean mixed liquid; the soybean mixed liquid was filtered to remove large particles of impurities, and then centrifuged at a speed of 4000 r / min for 30 minutes, and the supernatant was taken to obtain a soybean urease solution; (2) Preparation of a binder: Using calcium lignin sulfonate as a calcium source and urea as a urea source, dissolving calcium lignin sulfonate in deionized water, adding urea, and stirring the mixture thoroughly to obtain a binder. The concentration of calcium lignin sulfonate in the binder is 1 mol / L, and the concentration of urea is 1 mol / L. (3) Sample preparation: Weathered red sandstone test blocks from Sichuan and Chongqing were selected to simulate the deterioration state of actual cultural relics; (4) Preparation and use of repair materials: The soybean urease solution and the binder prepared in the above steps (1) and (2) were mixed evenly by a micro-mist spraying method, and then sprayed evenly on the sample surface and crack area in batches; according to the on-site monitoring data, the temperature was set to 35°C, the humidity was set to 90%, and the pH value was set to 8 to allow for full reaction, and then allowed to stand for curing.

[0021] Comparative Example 1 (1) Extraction of soybean urease: fresh soybeans were dried at 40°C for 24 hours, and then crushed to make them evenly dispersed to obtain soybean fine powder; the soybean fine powder was added to deionized water, stirred on a magnetic stirrer for 30 minutes, and refrigerated at 4°C for 24 hours to obtain a soybean mixed liquid; the soybean mixed liquid was filtered to remove large particles of impurities, and then centrifuged at a speed of 4000 r / min for 30 minutes, and the supernatant was taken to obtain a soybean urease solution; (2) Preparation of cementing liquid: using calcium chloride as a calcium source and urea as a urea source, dissolving calcium chloride in deionized water, adding urea, and stirring thoroughly to obtain a cementing liquid, wherein the concentration of calcium chloride in the cementing liquid is 1 mol / L, and the concentration of urea is 1 mol / L; (3) Sample preparation: Weathered red sandstone test blocks from Sichuan and Chongqing were selected to simulate the deterioration state of actual cultural relics; (4) Preparation and use of repair materials: The soybean urease solution and the binder prepared in the above steps (1) and (2) were mixed evenly by a micro-mist spraying method, and then sprayed evenly on the sample surface and crack area in batches; according to the on-site monitoring data, the temperature was set to 35°C, the humidity was set to 90%, and the pH value was set to 8 to allow for full reaction, and then allowed to stand for curing.

[0022] After curing for 7 days, the mechanical properties test, color difference analysis and air permeability evaluation were carried out on the samples before reinforcement and the samples after reinforcement of the above-mentioned embodiment 1 and comparative example 1 to verify the reinforcement effect. The results are shown in the following tables 1-2 and Figure 2-5 ; Table 1 Comparison of strength parameters

[0023] Table 2 Color difference comparison

[0024] Conclusion: It can be seen from Table 1 that compared with Comparative Example 1, the porosity of the sample in Example 1 is improved after reinforcement, and the water permeability and air permeability are better; Figure 2 As shown in Table 2, compared with Comparative Example 1, the color difference of the reinforced sample in Example 1 is smaller and close to the color of the original rock; Figure 3 It can be seen that with the increase of reinforcement times, the compressive strength of the sample is significantly improved, the improvement effect of Example 1 is 49.76%, and that of Comparative Example 1 is 53.46%; Figure 4 It can be seen that after the reinforcement of Example 1, the contact angle of the sample surface increased significantly from about 37.47° before reinforcement to about 71.29° after reinforcement, and the surface hydrophobicity was significantly enhanced.

[0025] In addition, tensile strength tests were conducted on the calcium carbonate products produced on the surfaces of the samples before reinforcement and the samples of Example 1 and Comparative Example 1 after reinforcement. The results are shown in Table 3 below.

[0026] Table 3 Comparison of tensile strength

[0027] Conclusion: It can be seen from Table 3 that the calcium carbonate reinforced products generated after reinforcement in Example 1 and Comparative Example 1 have lower strength than the sample body. Compared with Comparative Example 1, the reinforced product of Example 1 has lower tensile strength and does not cause additional damage to the sample when it fails.

[0028] In summary, the present invention provides a method for preparing a binder using calcium lignin sulfonate to replace the traditional calcium chloride calcium source, which can effectively reduce the whitening phenomenon of the rock after reinforcement; after reinforcement, good water permeability and air permeability can be maintained, and the penetration inhibition effect can be avoided to a certain extent; after reinforcement, the hydrophilicity of the rock surface is significantly reduced, and the waterproof performance is improved, which is suitable for the protection of stone cultural relics that require waterproof and moisture-proof protection; the calcium carbonate reinforcement product produced on the surface of the sample not only plays a role in weathering prevention, but also has a lower strength than the sample body, and can act as a sacrificial layer when it is damaged, avoiding additional damage to the main body of the cultural relic.

[0029] Example 2: Soybean urease activity test (1) Experimental conditions: In order to evaluate the activity of soybean urease under actual environmental conditions, the test was set based on the on-site monitoring results. The experimental temperature was controlled at 5-40°C. On the basis of covering the weak alkaline conditions on site (approximately 7.45-8.25), the pH range was expanded to 3-10 to comprehensively evaluate the urease activity under different acid-base environments.

[0030] (2) Experimental method: A test tube crossover design was used. 10 mL of soybean urease solution extracted according to the method provided by the present invention was mixed with 10 mL of 1 mol / L urea solution to start the reaction. During the process of urease-catalyzed urea hydrolysis, conductive ions are released, causing the conductivity of the solution to gradually increase. Since the initial hydrolysis rate of urea is closely related to the activity of urease, the rate of increase of conductivity can be used as an indirect indicator for evaluating urease activity.

[0031] Under the set temperature and pH conditions, the mixture of soybean urease solution and urea solution was allowed to react for 30 minutes. The conductivity of the solution was then measured using a conductivity meter. The electrode was inserted into the test tube and gently shaken to remove the bubbles in the electrode. The conductivity was recorded after the reading stabilized. The reading was taken once every minute, and the average value was taken after 10 consecutive recordings to calculate the activity level of urease. The test results were plotted as a bar graph, see Figure 6 .

[0032] in conclusion: Figure 6 The results show that soybean urease exhibits good catalytic activity in a wide range of conditions, including temperature of 5-40℃ and pH = 3-10, especially under conditions close to the actual field conditions (temperature of 30-40℃ and pH = 7.5-8.0), the urease activity is high and the conductivity increases significantly. This proves that soybean urease has good adaptability and reaction efficiency in the slightly alkaline field environment of the current project, strong weather resistance, and has practical application potential as a key catalyst in the EICP reaction, providing reliable biomaterial basic support for the subsequent reinforcement of stone cultural relics in the humid and warm natural environment of Sichuan and Chongqing.

[0033] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybeans, characterized in that: The steps include: S1. Extraction of soybean urease: fresh soybeans are dried and crushed to make them evenly dispersed to obtain soybean fine powder; the soybean fine powder is added to deionized water, stirred on a magnetic stirrer, and refrigerated to obtain a soybean mixed solution; the soybean mixed solution is filtered and centrifuged, and the supernatant is taken to obtain a soybean urease solution; S2. Preparation of a binder: using calcium lignin sulfonate as a calcium source and urea as a urea source, dissolving calcium lignin sulfonate in deionized water, adding urea, and stirring well to obtain a binder; S3, preparation and use of repair materials: the soybean urease solution and the cementing liquid are mixed, and applied to the surface of the cultural relics in batches by a micro-mist spraying method; after spraying, the cultural relics are solidified and maintained; The concentration of calcium lignin sulfonate in the binder is 1-10 mol / L, the concentration of urea is 1-10 mol / L, and the molar concentration ratio of calcium lignin sulfonate to urea is 1:

1.

2. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 1, characterized in that: In S1, the drying temperature is 40-45°C and the drying time is 23-25h.

3. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 2, characterized in that: In S1, the drying temperature is 40°C and the drying time is 24h.

4. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 1, characterized in that: In S1, the stirring time is 20-40 min, the refrigeration temperature is 4-5° C., and the refrigeration time is 24-28 h.

5. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 4, characterized in that: In S1, the stirring time is 30 min, the refrigeration temperature is 4°C, and the refrigeration time is 24 h.

6. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 1, characterized in that: In S1, the centrifugal speed is 4000-5000 r / min, and the centrifugal time is 30-40 min.

7. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 6, characterized in that: In S1, the centrifugal speed is 4000 r / min and the centrifugal time is 30 min.

8. The method for reinforcing red sandstone cultural relics in Sichuan and Chongqing based on the mineralization induced by urease extracted from soybean according to claim 1, characterized in that: In S2, the calcium lignin sulfonate is made from waste paper as raw material.

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