A method for desalination of immovable masonry cultural relics

Abstract

The present invention discloses a method for desalting immovable masonry cultural relics, wherein the salt is a soluble sulfate or chloride salt, and a double-layer sponge is applied with an infrared heat source, and a precipitation agent in the oil-absorbing sponge and soluble salt ions rapidly undergo precipitation reaction in the water-saturated sponge layer, resulting in a rapid decrease in the concentration of soluble salt ions around the contact surface to form a concentration difference, thereby accelerating the dissolution of soluble salts and ion migration in the cultural relics; at the same time, an external heat source can accelerate the volatilization of the solution on the outside of the oil-absorbing sponge, thereby driving the outward migration of soluble salt ions, and avoiding the inward diffusion of the precipitant to form barium sulfate precipitation in the cultural relics. The method is based on the idea of ​​accelerating ion diffusion, has the advantages of being fast, efficient and convenient, is suitable for desalting various cultural relics with complex surfaces, and can provide technical support for the removal of sulfates in various immovable cultural relics and cultural relics with fragile surface layers.

Description

Technical Field

[0001] The invention belongs to the technical field of cultural relic protection, and in particular relates to desalination protection treatment of outdoor large-scale masonry cultural relics, and desalination treatment of cultural relics eroded by salt damage. Background Art

[0002] Large outdoor masonry cultural relics are an extremely important type of cultural relics in historical and cultural heritage. However, because they are in an open or semi-enclosed environment, they are easily eroded by soluble salts, and surface weathering phenomena such as salt precipitation, crispness and peeling caused by salt damage occur. For example, the Xi'an city wall has mud, peeling and alkali efflux on the surface due to soluble salt erosion; ceramic cultural relics in Longxian and other museums have been subjected to stress corrosion due to chloride crystallization until the crispness and peeling are completely gone. The porous structure of ceramic cultural relics is conducive to the enrichment of harmful soluble salts, and thus they are damaged by stress during the dissolution-crystallization process of soluble salts, resulting in crispness and peeling. Due to the large size and immovability of outdoor masonry cultural relics, it is impossible to use auxiliary desalination methods such as solution immersion and ultrasonic treatment like small masonry cultural relics, which makes desalination difficult. At the same time, the fragile ceramic cultural relics have low strength themselves, and there is a painted layer on the surface of painted ceramic cultural relics, which cannot be achieved by immersion and ultrasonic assisted desalination.

[0003] At present, the paper pulp paste method is mainly used for desalination of the surface of large outdoor masonry cultural relics. For small ceramic cultural relics with better texture, there are a series of desalination methods. For example, a method for removing sulfate from outdoor crisp brick cultural relics (201711118861.X) is to convert sodium sulfate into barium sulfate and precipitate it in the cultural relic body. This method has the hidden danger of harmful salts hidden inside the cultural relic body and is easy to aggravate the stress damage of the cultural relic body; Wang Liqin et al. proposed in "Application of Composite Material Pasting Desalination Technology in Desalination of Fragile Pottery" to use super absorbent resin to make composite desalination pads with carrier materials to desalinate objects. However, this technology requires burying the cultural relics in a sandbox at a certain depth and pressurizing them, which will cause a certain degree of damage to fragile cultural relics; In addition, Su Bomin et al. designed a desalination board in "Experimental Study on the Application of New Synthetic Desalination Materials in the Treatment of Salt Damage Murals in Mogao Grottoes" to desalinate murals through absorbent materials. This method can remove more white crystalline salts precipitated on the surface of the murals after drying, while the residual crystalline salt inside will still damage the cultural relics. Summary of the invention

[0004] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and to provide a method for removing soluble salts from immovable masonry cultural relics by using double-layer cotton application and auxiliary heating.

[0005] In view of the above purpose, the technical scheme adopted by the present invention is as follows: spray deionized water on the brick and stone cultural relics to dissolve harmful soluble salts, apply a water-absorbing cotton layer saturated with deionized water, and then apply an oil-absorbing cotton layer saturated with precipitant solution on the water-absorbing cotton layer, and then irradiate with infrared light to heat the oil-absorbing cotton layer at a temperature not exceeding 40° C. for 5 to 15 minutes. Repeat the above method 5 to 10 times according to the desalination effect.

[0006] The above-mentioned soluble salt is a sulfate or a chloride; wherein, when the soluble salt is a sulfate, the precipitant solution is a reverse microemulsion with a barium acetate aqueous solution as the aqueous phase; when the soluble salt is a chloride, the precipitant solution is a reverse microemulsion with a silver acetate aqueous solution as the aqueous phase.

[0007] The reverse microemulsion consists of an oil phase, an aqueous phase, a compound surfactant and a co-surfactant, wherein the oil phase is cyclohexane, the aqueous phase is a 0.05-0.30 mol / L barium acetate aqueous solution or a 0.05-0.30 mol / L silver acetate aqueous solution, the amount of the aqueous phase added is 1%-3% of the volume of the oil phase, the compound surfactant is a mixture of polyoxyethylene castor oil and Span-80 in a mass ratio of 1:0.6-3.0, the compound surfactant accounts for 1%-2% of the total volume of the reverse microemulsion, the co-surfactant is ethanol, and the mass volume ratio of the compound surfactant to the co-surfactant is 1g:1-2mL.

[0008] Furthermore, it is preferred that the thickness of the water-absorbing cotton layer is 5 to 10 mm, and the thickness of the oil-absorbing cotton layer is 5 to 20 mm.

[0009] Furthermore, it is preferred to use 200-300W infrared lamp for irradiation, and adjust the distance so that the surface temperature of the oil-absorbing cotton layer does not exceed 40°C.

[0010] The beneficial effects of the present invention are as follows:

[0011] The present invention adopts a method of double-layer cotton application and infrared heat source heating to remove soluble salts in immovable brick and stone cultural relics, that is: the first layer is a water-absorbing cotton layer, which is soaked in deionized water until saturated (the cultural relic body can be sprayed with deionized water as needed to dissolve harmful soluble salts); the second layer is an oil-absorbing cotton layer, which is soaked in a precipitant solution until saturated; at the same time, an external heating device such as an infrared lamp is used to heat the oil-absorbing cotton layer. The precipitant in the oil-absorbing cotton layer and the soluble salt ions rapidly undergo precipitation reaction in the water-absorbing cotton layer saturated with deionized water, resulting in a rapid decrease in the concentration of soluble salt ions around the contact surface to form a concentration difference, which accelerates the dissolution and ion migration of soluble salts in the cultural relics; at the same time, the entire desalination process is assisted by external heat source heating treatment (the heat source temperature is controlled to be slightly higher than room temperature and not more than 40°C. Too high a temperature will cause the oil phase to evaporate too quickly, and too low a temperature will reduce the outward migration rate of soluble salt ions). The external heat source can accelerate the volatilization of the solution on the outside of the oil-absorbing cotton layer, thereby driving the outward migration of soluble salt ions and avoiding the inward diffusion of the precipitant to form precipitation in the cultural relics. This method is based on the idea of ​​quickly forming a concentration difference of soluble salt ions and accelerating ion diffusion through precipitation reactions. The precipitant is used to achieve rapid removal of soluble salts, and the isolation water layer is used to prevent the precipitant from diffusing into the cultural relics. The external heating method is used to accelerate the outward diffusion of the solution. The concentration of soluble salt ions is rapidly reduced, thereby forming a solution concentration difference to accelerate the diffusion of soluble salt ions, and the harmful soluble salts inside the cultural relics are quickly removed. The method of the present invention is simple to operate and has the advantages of rapid, efficient and convenient desalination. Different precipitants can be used to achieve rapid and efficient removal of soluble salts inside large outdoor masonry cultural relics. It is suitable for desalination treatment of various cultural relics with complex surfaces and can provide technical support for the removal of sulfate and chloride salts in various immovable cultural relics and cultural relics with fragile surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the desalination method of the present invention.

[0013] Figure 2 This is the appearance and particle size diagram of the reverse microemulsion obtained in Example 1.

[0014] Figure 3 These are the initial photos of the seven brick simulation samples in methods 1 to 7 and their appearance after being immersed in NaSO4 aqueous solution and after desalination.

[0015] Figure 4 This is a bar graph of the sulfur content of the seven brick simulation samples before and after desalination in methods 1 to 7. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0017] Example 1

[0018] like Figure 1 As shown, after spraying deionized water on the masonry cultural relics body with sulfate salt damage to dissolve the harmful soluble salt, a water-absorbing sponge layer (10 mm thick) saturated with deionized water is first applied to the masonry cultural relics body, and then an oil-absorbing sponge layer (10 mm thick) saturated with reverse microemulsion with 0.2 mol / L barium acetate aqueous solution as the water phase is applied to the water-absorbing sponge layer, and then irradiated with a 250W infrared lamp and heated at no more than 40°C for 10 minutes. The above method is repeated 10 times according to the desalination effect. The preparation method of the reverse microemulsion is as follows: 0.6 g of polyoxyethylene castor oil EL (HLB = 12.5) and 0.4 g of Span-80 (HLB = 4.3) are taken, mixed evenly, 1.5 mL of ethanol is added thereto and stirred evenly, the mixed solution is added to 100 mL of cyclohexane stirred at room temperature, and 1.5 mL of 0.2 mol / L barium acetate aqueous solution is added dropwise to the system, stirring continuously for 30 min, standing for 2 h, and taking the supernatant, which is the desired reverse microemulsion, which has a transparent appearance and a particle size concentrated around 200 nm. Figure 2 shown.

[0019] Example 2

[0020] Deionized water was sprayed on the masonry cultural relics with chloride salt damage to dissolve the harmful soluble salts, and then a water-absorbing sponge layer (10 mm thick) saturated with deionized water was pasted on the masonry cultural relics, and then an oil-absorbing sponge layer (10 mm thick) saturated with reverse microemulsion with 0.2 mol / L silver acetate aqueous solution as the water phase was pasted on the water-absorbing sponge layer, and then irradiated with a 250W infrared lamp and heated at no more than 40°C for 10 minutes. The above method was repeated 10 times according to the desalination effect. The preparation method of the reverse microemulsion is as follows: 0.6 g of polyoxyethylene castor oil EL (HLB=12.5) and 0.4 g of Span-80 (HLB=4.3) are taken, mixed evenly, 1.5 mL of ethanol is added thereto and stirred evenly, the mixed solution is added to 100 mL of cyclohexane stirred at room temperature, and 1.5 mL of 0.2 mol / L silver acetate aqueous solution is added dropwise to the system, stirring is continued for 30 min, and then the mixture is allowed to stand for 2 h, and the supernatant is taken, which is the desired reverse microemulsion.

[0021] To demonstrate the beneficial effects of the present invention, the inventors used different methods to desalinate brick simulation samples of 4cm×4cm×2cm in size. The specific steps are as follows: seven brick simulation samples were ultrasonically cleaned and then dried, soaked in a 5% NaSO4 aqueous solution for one week, and then taken out and dried in the shade. The following methods were used to apply desalination to seven brick simulation samples, which were recorded as samples No. 1 to No. 7.

[0022] Method 1

[0023] Deionized water double-layer application method: Soak two 10mm thick absorbent sponges in deionized water in advance to make them saturated with deionized water, and then apply the two saturated deionized water absorbent sponges to the surface of the brick simulation sample for desalination treatment. Repeat this method 10 times, 15 minutes each time. Dry naturally after desalination.

[0024] Method 2

[0025] Double-layer application of barium acetate aqueous solution: Soak two 10mm thick water-absorbing sponges in 0.2mol / L barium acetate aqueous solution in advance to saturate the barium acetate aqueous solution, and then apply the two water-absorbing sponges saturated with barium acetate aqueous solution to the surface of the brick simulation sample for desalination treatment. Repeat this method 10 times, 15 minutes each time. Dry naturally after desalination.

[0026] Method 3

[0027] Barium acetate reverse microemulsion double-layer application method: soak two 10 mm thick oil-absorbing sponges in a reverse microemulsion (preparation method is the same as in Example 1) with a 0.2 mol / L barium acetate aqueous solution as the aqueous phase, so that they are saturated with the reverse microemulsion, and then stack and apply the two saturated reverse microemulsion oil-absorbing sponges to the surface of the brick simulation sample for desalination treatment. Repeat this method 10 times, 15 minutes each time. Dry naturally after desalination.

[0028] Method 4:

[0029] Deionized water / barium acetate aqueous solution composite application method: prepare two 10mm thick water-absorbing sponges in advance, soak one in deionized water to make it saturated with deionized water, and soak the other in 0.2mol / L barium acetate aqueous solution to make it saturated with barium acetate aqueous solution. Apply the water-absorbing sponge saturated with deionized water to the surface of the brick simulation sample, and then stack the water-absorbing sponge saturated with barium acetate aqueous solution on it for desalination treatment. Repeat this method 10 times, 15 minutes each time. Dry naturally after desalination.

[0030] Method 5:

[0031] Deionized water / barium acetate aqueous solution composite application method plus infrared light source: prepare two 10mm thick water-absorbing sponges in advance, soak one in deionized water to make it saturated with deionized water, and soak the other in 0.2mol / L barium acetate aqueous solution to make it saturated with barium acetate aqueous solution. Apply the water-absorbing sponge saturated with deionized water to the surface of the brick simulation sample, and then stack the water-absorbing sponge saturated with barium acetate aqueous solution on it, and apply infrared light source 20cm away from the top layer of water-absorbing sponge. The irradiation temperature of the infrared lamp does not exceed 40℃ for desalination treatment. Repeat this method 10 times, 15min each time. Dry naturally after desalination.

[0032] Method 6:

[0033] Deionized water / barium acetate reverse microemulsion composite application method: soak a 10 mm thick water-absorbing sponge in deionized water in advance to saturate it with deionized water, and soak a 10 mm thick oil-absorbing sponge in a reverse microemulsion (preparation method is the same as Example 1) with 0.2 mol / L barium acetate aqueous solution as the aqueous phase to saturate it with reverse microemulsion. Apply the water-absorbing sponge saturated with deionized water to the surface of the brick simulation sample, and then stack the oil-absorbing sponge saturated with reverse microemulsion for desalination treatment. Repeat this method 10 times, 15 minutes each time. Dry naturally after desalination.

[0034] Method 7:

[0035] Deionized water / barium acetate reverse microemulsion composite application method plus infrared light source: soak a 10mm thick water-absorbing sponge in deionized water in advance to saturate it with deionized water, and soak a 10mm thick oil-absorbing cotton in a reverse microemulsion with a 0.2mol / L barium acetate aqueous solution as the aqueous phase (preparation method is the same as Example 1) to saturate it with reverse microemulsion. Apply the water-absorbing sponge saturated with deionized water to the surface of the brick simulation sample, and then stack the oil-absorbing sponge saturated with reverse microemulsion on it, and irradiate it with an infrared light source 20cm away from the top layer of the oil-absorbing cotton layer. The irradiation temperature of the infrared lamp does not exceed 40°C for desalination treatment. Repeat this method 10 times, 10 minutes each time. Dry naturally after desalination.

[0036] The initial photos of the seven brick simulation samples in methods 1 to 7 and their appearance after being soaked in NaSO4 aqueous solution and after desalination are as follows Figure 3 As shown. Figure 3 It can be seen that the appearance of the bricks after desalination is very different from that of the initial bricks.

[0037] The sulfur content on the surface of seven brick simulation samples before and after the above treatment was analyzed by XRF, and the resulting bar graph is as follows: Figure 4As shown, the results show that the deionized water desalination method is time-consuming and inefficient, while the reverse microemulsion desalination can solve this problem well. During the implementation process, heat source assistance is performed to help the evaporation of ions in the sponge layer solution, avoid excessive solution penetration, and effectively remove harmful soluble salts in cultural relics. The operation method of the present invention is simple, has good desalination effect and high desalination efficiency.

Claims

1. A method for desalination of immovable masonry cultural relics, characterized in that: Spray deionized water on the brick and stone cultural relics to dissolve harmful soluble salts, then apply a water-absorbing cotton layer saturated with deionized water, and then apply an oil-absorbing cotton layer saturated with precipitant solution on the water-absorbing cotton layer, and then use infrared light to irradiate and heat the oil-absorbing cotton layer at no more than 40°C for 5 to 15 minutes; Repeat the above method 5 to 10 times according to the desalination effect; The soluble salt is a sulfate or a chloride; when the soluble salt is a sulfate, the precipitant solution is a reverse microemulsion with a barium acetate aqueous solution as the aqueous phase; when the soluble salt is a chloride, the precipitant solution is a reverse microemulsion with a silver acetate aqueous solution as the aqueous phase.

2. The method for desalination of immovable masonry cultural relics according to claim 1, characterized in that: The reverse microemulsion consists of an oil phase, an aqueous phase, a compound surfactant and a co-surfactant, wherein the oil phase is cyclohexane, the aqueous phase is a 0.05-0.30 mol / L barium acetate aqueous solution or a 0.05-0.30 mol / L silver acetate aqueous solution, the amount of the aqueous phase added is 1%-3% of the volume of the oil phase, the compound surfactant is a mixture of polyoxyethylene castor oil and Span-80 in a mass ratio of 1:0.6-3.0, the compound surfactant accounts for 1%-2% of the total volume of the reverse microemulsion, the co-surfactant is ethanol, and the mass volume ratio of the compound surfactant to the co-surfactant is 1g:1-2mL.

3. The method for desalination of immovable masonry cultural relics according to claim 1, characterized in that: The thickness of the water-absorbing cotton layer is 5 to 10 mm, and the thickness of the oil-absorbing cotton layer is 5 to 20 mm.

4. The method for desalination of immovable masonry cultural relics according to claim 1, characterized in that: Use 200-300W infrared lamp to irradiate, and adjust the distance so that the surface temperature of the oil-absorbing cotton layer does not exceed 40℃.

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