Method for removing iron sulfide compounds in wood sample

Abstract

The invention relates to the technical field of iron sulfide removal, and discloses a method for removing iron sulfide in a wood sample. The method comprises the following steps: dipping a wood sample in a chelating agent aqueous solution, and removing a sulfur-iron compound; wherein the chelating agent is selected from hydroxyethyl ethylenediamine triacetic acid trisodium salt, iminodisuccinic acid tetrasodium salt or a combination of the hydroxyethyl ethylenediamine triacetic acid trisodium salt and the iminodisuccinic acid tetrasodium salt. According to the method provided by the invention, the hydroxyethyl ethylenediamine triacetic acid trisodium salt, the iminodisuccinate tetrasodium salt or a combination thereof is selected as the desalting chelating agent, and compared with other chelating agents, the hydroxyethyl ethylenediamine triacetic acid trisodium salt and the iminodisuccinate tetrasodium salt are excellent in desalting effect, higher in safety and environmental protection property and lower in cost; when the method is applied to protection of the waterlogged wooden cultural relics and removal of sulfur and iron compounds contained in the waterlogged wooden cultural relics, the method can be suitable for ocean water-out wooden cultural relics or high-salt stratum soil-out wooden cultural relics, and the method is wide in application range and high in practicability and has important significance on promotion of protection of the waterlogged wooden cultural relics.

Description

Technical Field

[0001] The present invention relates to the technical field of removing iron sulfide compounds, and particularly to a method for removing iron sulfide compounds from wood samples. Background Art

[0002] The average concentration of SO in seawater is 29 mmol / L, which is hundreds of times that in fresh water (0.1 mmol / L). In the anoxic environment at the bottom of the sea, sulfate-reducing bacteria (SRB) can reduce SO 4 2- to S 4 2- , and then generate H 2- S. The reaction equations are SO 2 4 2- + 4H 2 = S 2- + 4H 2 O, 2H + + S 2- = H 2 S. These H 2 S can react with Fe(II) derived from corroded ironware to form various iron sulfide compounds such as pyrite (FeS 2 ), marcasite (FeS), and greigite (Fe 3 S 4 ).

[0003] Iron sulfide compounds are usually deposited in the wooden cultural relics from marine effluent. After the wooden cultural relics are salvaged from the water, the iron sulfide compounds will oxidize when they encounter air and moisture in the environment, generating sulfuric acid and various sulfates, causing an increase in the acidity of the cultural relics. The specific reactions are as follows: FeS 2 (s) + 7 / 2O 2 + (n + 1)H 2 O → FeSO 4 ·nH 2 O(s) + H 2 SO 4 (aq); FeS 2 (s) + 15 / 4O 2 + 5 / 2H 2 O → FeOOH(s) + 2H 2 SO 4 (aq). If this process is not controlled, the organic matter will gradually degrade, ultimately leading to the collapse of the hull and causing irreparable losses.

[0004] ​Regarding the problem of wood acidification caused by iron sulfide compounds, the existing solutions can be roughly divided into two categories: one is the removal of iron sulfide compounds, and the other is the neutralization of acidification products. Among them, the neutralization of acidification products is applicable to large-scale wooden cultural relics that have completed the preliminary protection treatment and are in the display process. However, this method only treats the symptoms but not the root cause, the effect is limited to the wood surface, and the durability is poor and it is easy to recur. Therefore, for wooden cultural relics unearthed from the sea or high-salt strata and analyzed and detected to have a risk of iron sulfide compound deposition, the iron sulfide compound removal treatment should be carried out first, and then subsequent protection steps such as soluble salt removal, dehydration and shaping, and filling and strengthening should be carried out. Otherwise, it may pose great potential hazards to the protection and preservation of these wooden cultural relics.

[0005] At present, iron sulfide compounds in wood are mainly removed by making complexing reagents form stable complexes with iron. Commonly used complexing agents include ethylenediamine-di(2-hydroxy-4-tolyl)acetic acid (EDDHMA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (EDTPA), etc. Among them, EDDHMA is a compound with extremely strong ability to form complexes with iron ions, which can increase the solubility of iron sulfide compounds and effectively remove iron ions. However, this process must be carried out under alkaline conditions, and the risk of wood degradation caused by the alkaline environment is relatively high; EDTA has been listed as a prohibited substance by the European Union's 2002 / 371 / EC due to its poor biodegradability in the water environment and its metal complexes; EDTPA has the defects of relatively high toxicity and relatively high price.

[0006] The volume of waterlogged wooden cultural relics such as boats is large, and a large amount of complexing agent is required for desalination treatment, and a large amount of waste liquid will also be generated. Therefore, developing a method for removing iron sulfide compounds that is efficient, environmentally friendly, and low-cost is of great significance for the protection of waterlogged wooden cultural relics. Summary of the Invention

[0007] The present invention aims to at least solve one of the above technical problems existing in the prior art. For this reason, one of the purposes of the present invention is to provide a method for removing iron sulfide compounds from wooden samples.

[0008] The second purpose of the present invention is to provide the application of this method in the protection of waterlogged wooden cultural relics.

[0009] In order to achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0010] The first aspect of the present invention provides a method for removing iron sulfide compounds from wooden samples, including the following steps:

[0011] Immerse the wooden sample in an aqueous solution of a chelating agent to remove iron sulfide compounds;

[0012] Among them, the chelating agent is selected from trisodium hydroxyethyl ethylenediaminetriacetate, tetrasodium iminodisuccinate or a combination thereof.

[0013] In some embodiments of the present invention, the pH of the chelating agent aqueous solution is 5-9.

[0014] In some specific embodiments of the present invention, the pH of the chelating agent aqueous solution is 5-8.

[0015] In some preferred embodiments of the present invention, the pH of the chelating agent aqueous solution is 6-8.

[0016] In the present invention, the chelating agent aqueous solution can remove iron sulfide compounds in the woody sample within the range of pH = 5-9. When pH = 6-8, the dissolution ability of iron and sulfur elements is relatively balanced, and the desalting effect is good. Moreover, under such weak acidic to weak alkaline conditions, the risk of wood degradation caused by a strong alkaline environment can be reduced, and the dosage of alkaline pH adjustment reagents can be reduced, thereby reducing costs.

[0017] In some embodiments of the present invention, the concentration of the chelating agent aqueous solution is 1-30 mmol / L.

[0018] In some specific embodiments of the present invention, the concentration of the chelating agent aqueous solution is 20-30 mmol / L.

[0019] In some preferred embodiments of the present invention, when the chelating agent is trisodium hydroxyethyl ethylenediaminetriacetate, the concentration of the chelating agent aqueous solution is 5-20 mmol / L.

[0020] In some preferred embodiments of the present invention, when the chelating agent is tetrasodium iminodisuccinate, the concentration of the chelating agent aqueous solution is 25-30 mmol / L.

[0021] In the present invention, the chelating agent aqueous solution used has the ability to remove iron sulfide compounds in the woody sample within the concentration range of 1-30 mmol / L, indicating that the chelating agent has excellent ability to remove poorly soluble salts, which is beneficial to reducing the dosage of the chelating agent, reducing costs, and reducing the environmental impact caused by the large amount of chelating agent used.

[0022] In some embodiments of the present invention, the solid-liquid ratio of the woody sample to the chelating agent aqueous solution is 1 g:(1-2) L.

[0023] In some specific embodiments of the present invention, the solid-liquid ratio of the woody sample to the chelating agent aqueous solution is 1 g:(1-1.5) L.

[0024] In some embodiments of the present invention, the temperature of the impregnation is 15-50 °C.

[0025] In some specific embodiments of the present invention, the temperature of the impregnation is 20 - 25 °C.

[0026] In the present invention, the temperature of the impregnation is considered in terms of the removal efficiency of the iron sulfide compound and the influence of temperature on the structure of the wood sample. Generally, an increase in temperature will accelerate the chemical reaction rate, which is beneficial to the complexation reaction between the chelating agent and metal ions in the iron sulfide compound within a certain range, improving the removal efficiency. If the temperature is too low (below 15 °C), the reaction rate between the chelating agent and the iron sulfide compound will slow down, and the removal efficiency will decrease significantly. If the temperature is too high (above 50 °C), it is likely to cause the reaction to proceed violently, increasing side reactions. In addition, when the temperature is between 15 - 50 °C, it generally will not cause obvious damage to the structure and properties of the wood. If the temperature exceeds 50 °C, it may cause thermal degradation of components such as cellulose and hemicellulose in the wood, resulting in problems such as reduced strength, color change, and poor toughness of the wood. When the impregnation temperature is 20 - 25 °C (room temperature), it can not only ensure the removal efficiency of the iron sulfide compound, reduce the influence of temperature on the structure of the wood sample, but also avoid the process from being too cumbersome due to heating or cooling.

[0027] In some embodiments of the present invention, the method further includes the step of real - time monitoring the contents of Fe element and S element in the chelating agent aqueous solution, and the impregnation ends when the contents of both Fe element and S element no longer increase.

[0028] In some embodiments of the present invention, the time of the impregnation is 10 - 30 d.

[0029] In some specific embodiments of the present invention, the time of the impregnation is 15 - 25 d.

[0030] In the present invention, there is no particular limitation on the specific wood species of the wood sample, and the method is generally applicable to wood samples of various wood species.

[0031] In some specific embodiments of the present invention, the wood species of the wood sample include Pinus wood, Pinus hard pine, and Dipterocarpaceae trees.

[0032] In some embodiments of the present invention, the wood sample is pretreated before the impregnation treatment, and the pretreatment includes removing surface impurities.

[0033] The second aspect of the present invention provides the application of the method described in the first aspect of the present invention in the protection of wood products.

[0034] In some embodiments of the present invention, the protection is to remove iron sulfide compounds from wood products.

[0035] In some embodiments of the present invention, the wood products include water - saturated wood products.

[0036] In some embodiments of the present invention, the water-saturated wood products include wood products soaked in seawater for a long time or buried in high-salt strata for a long time.

[0037] In some embodiments of the present invention, the high-salt strata include marine sedimentary plains or alluvial plains.

[0038] In some embodiments of the present invention, the wood products soaked in seawater for a long time include marine-exposed wood cultural relics.

[0039] In some embodiments of the present invention, the wood products buried in high-salt strata for a long time include wood cultural relics unearthed from high-salt strata.

[0040] In some embodiments of the present invention, in the wood products soaked in seawater for a long time, the content of Fe element is 5wt%-15wt%, and the content of S element is 2wt%-15wt%.

[0041] In some specific embodiments of the present invention, in the wood products soaked in seawater for a long time, the content of Fe element is 10wt%-15wt%, and the content of S element is 10wt%-15wt%.

[0042] In some embodiments of the present invention, in the wood products buried in high-salt strata for a long time, the content of Fe element is 0.5wt%-5wt%, and the content of S element is 1wt%-5wt%.

[0043] In some specific embodiments of the present invention, in the wood products buried in high-salt strata for a long time, the content of Fe element is 1wt%-4wt%, and the content of S element is 2wt%-5wt%.

[0044] In the present invention, the content of iron sulfide compounds in water-saturated wood products is related to their soaking / burial time and the differences in the pore structures of different wood species. Soaking / burial for several years or hundreds of years will cause the deposition of iron sulfide compounds, and with the extension of time, the deposition amount of iron sulfide compounds may increase. For wood products of wood species with loose texture and large porosity, iron sulfide compounds are more likely to deposit inside the products; for wood products of wood species with dense texture and small porosity, iron sulfide compounds are more likely to deposit on the surface of the products. And during the soaking / burial period, the structure of water-saturated wood products may also change under the influence of the environment. Therefore, for water-saturated wood products with the actual content of iron sulfide compounds (or the content of Fe element and S element) not within the above range, the same desalination effect can be achieved by adjusting the dosage of the chelating agent or the impregnation time.

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] 1) The method for removing iron sulfide compounds from woody samples provided by the present invention selects trisodium hydroxyethylenediaminetriacetate, tetrasodium iminodisuccinate or a combination thereof as a desalting chelating agent. Compared with other chelating agents, trisodium hydroxyethylenediaminetriacetate and tetrasodium iminodisuccinate have excellent desalting effects, higher safety and environmental friendliness, and lower costs.

[0047] 2) The method for removing iron sulfide compounds from woody samples provided by the present invention can be widely applied to the protection of wood products, especially for removing iron sulfide compounds from waterlogged wood cultural relics of different wood species unearthed from the sea or high-salt strata. The method provided by the present invention has strong practicability, meets the protection requirements of wood products such as waterlogged wood cultural relics, and is of great significance for promoting the protection of waterlogged wood cultural relics. Description of the Drawings

[0048] Figure 1 It is a comparison chart of the removal effects of seven chelating agents on iron sulfide compounds in Example 1;

[0049] Figure 2 It is the desalting effect of HEDTA-3Na aqueous solution with different pH values in Example 2;

[0050] Figure 3 It is the desalting effect of IDS-4Na aqueous solution with different pH values in Example 2;

[0051] Figure 4 It is the desalting effect of HEDTA-3Na aqueous solution with different concentrations in Example 3;

[0052] Figure 5 It is the desalting effect of IDS-4Na aqueous solution with different concentrations in Example 3;

[0053] Figure 6 It is the appearance comparison of the specimen block XBJ before and after treatment with HEDTA-3Na aqueous solution in Example 4;

[0054] Figure 7 It is the appearance comparison of the specimen block XBJ before and after treatment with IDS-4Na aqueous solution in Example 4;

[0055] Figure 8 It is the appearance comparison of the specimen block MS before and after treatment with HEDTA-3Na aqueous solution in Example 5;

[0056] Figure 9 It is the appearance comparison of the specimen block MS before and after treatment with IDS-4Na aqueous solution in Example 5. Detailed Embodiments

[0057] The content of the present invention will be further described in detail through specific embodiments below. Unless otherwise specified, the raw materials, reagents or devices used in the embodiments can be obtained from conventional commercial channels or can be obtained by methods of the prior art. Unless otherwise specified, the test or measurement methods are conventional methods in the art.

[0058] Example 1

[0059] In this example, from the aspects of desalination effect, safety, environmental protection and cost, trisodium hydroxyethyl ethylenediaminetriacetate, tetrasodium iminodisuccinate were compared with five other common chelating agents to evaluate the applicability of these chelating agents in removing iron sulfide compounds from water-saturated wooden cultural relics:

[0060] Table 1 is the basic information table of the seven chelating agents in Example 1:

[0061] Table 1 Basic Information of the Seven Chelating Agents in Example 1

[0062]

[0063]

[0064] The specific method is as follows:

[0065] The seven chelating agents were respectively dissolved in water to prepare 200 mL of 10 mmol / L chelating agent aqueous solutions, and the pH of the solutions was adjusted to 7 with sodium hydroxide;

[0066] A sample block of waterlogged wooden cultural relic from the sea was taken. The wood species was identified as Pinus. Its Fe element content was 10.5 wt%, and the S element content was 2.2 wt%. It was ground into powder, and 7 portions of 0.2 g of sample powder were weighed and respectively put into tea bag bags;

[0067] At room temperature, the tea bag bags were respectively immersed in the seven chelating agent aqueous solutions, taken out after 15 d, and the contents of Fe element and S element in the solutions before and after soaking the sample powder were detected by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0068] Figure 1 For the comparison chart of the removal effects of the seven chelating agents on iron sulfide compounds in Example 1, from Figure 1It can be seen that after soaking the sample powder, in the GA-Na aqueous solution, the contents of Fe element and S element are similar and both are less than 10 mg / L, indicating that with GA-Na as the chelating agent, the dissolution effects of Fe element and S element are equivalent, but the overall desalting ability is weak; compared with GA-Na, in the CA aqueous solution, HEDP aqueous solution and EDTA-2Na aqueous solution, the contents of Fe element and S element increase slightly. Among them, the content of Fe element is about 13 mg / L, and the contents of S element are about 9 mg / L, 16 mg / L and 12 mg / L respectively, indicating that the desalting abilities of the three are slightly better than that of GA-Na; in the DETPA aqueous solution, the content of Fe element is about 24 mg / L, but the content of S element is only about 8 mg / L, indicating that the dissolution effects of Fe element and S element are unbalanced; compared with the above several chelating agents, in the HEDTA-3Na aqueous solution, the content of Fe element is about 26 mg / L and the content of S element is about 13 mg / L, and the desalting effect is the best; in the IDS-4Na aqueous solution, the content of Fe element is about 18 mg / L and the content of S element is about 9 mg / L, and the dissolution effects of Fe element and S element are more balanced than those of DETPA. In contrast, compared with the other chelating agents, HEDTA-3Na, IDS-4Na and DETPA have stronger abilities to form complexes with iron ions under the same conditions. However, the desalting effects of chelating agents on iron sulfide compounds need to be comprehensively reflected by the increments of Fe element and S element in the chelating agent aqueous solution. Therefore, the desalting effects of HEDTA-3Na and IDS-4Na are better.

[0069] Table 2 Comprehensive evaluation table of seven chelating agents in Example 1

[0070] Chelating agent Desalination effect Safety Environmental protection Cost HEDTA-3Na ★★★ ★★ ★★ ★★ IDS-4Na ★★ ★★★ ★★★ ★★ EDTA-2Na ★☆ ★★ ★★ ★★ DETPA ★★ ★ ★★ ★☆ HEDP ★☆ ★ ★★ ★ CA ★☆ ★★ ★★★ ★★ GA-Na ★ ★★★ ★★★ ★★★

[0071] Note: The desalting effect is evaluated with reference to Figure 1 For evaluation, the higher the star rating, the better the desalting effect; the safety is evaluated with reference to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), the higher the star rating, the better the safety; the environmental friendliness is evaluated with reference to the Water Environment Hazard (WGK) in Germany, the higher the star rating, the better the environmental friendliness; the cost is evaluated with reference to the quotations of Sigma-Aldrich Company in the United States and Jinjinle Chemical Co., Ltd., the higher the star rating, the lower the unit price.

[0072] Table 2 is the comprehensive evaluation table of seven chelating agents in Example 1. It can be seen from Table 2 that the desalination effect of HEDTA-3Na is the best, followed by DETPA and IDS-4Na. However, compared with HEDTA-3Na and IDS-4Na, DETPA has lower safety and environmental protection performance and a higher price. As for chelating agents such as GA-Na, CA, and EDTA-2Na, although they have good safety and environmental protection performance and moderate costs, they all have the defect of insufficient desalination ability. In addition to poor desalination ability, HEDP also has the same defects as DETPA, namely lower safety and environmental protection performance and a higher price. Chelating agents with lower safety and environmental protection performance have a high risk coefficient during use, are likely to have an adverse impact on the environment, and will also increase the difficulty of post-treatment of wastewater. Chelating agents with a higher price consume a large amount of chelating agent and have a higher cost when used for the removal of iron sulfide compounds in large-volume waterlogged wooden cultural relics such as boats. Therefore, when choosing a chelating agent, it is necessary to consider both the desalination effect and safety, environmental protection, and cost, so as to reduce the difficulty of waste liquid treatment, environmental pollution, and treatment cost while achieving efficient desalination. Compared with other chelating agents, HEDTA-3Na and IDS-4Na are significantly more suitable for removing iron sulfide compounds in waterlogged wooden cultural relics.

[0073] Example 2

[0074] In this example, the pH conditions for the removal of iron sulfide compounds by HEDTA-3Na and IDS-4Na were optimized:

[0075] Five portions of 200 mL of 10 mmol / L aqueous solutions of HEDTA-3Na and IDS-4Na were prepared, and the pH values of the aqueous solutions were adjusted to 5, 6, 7, 8, and 9 respectively;

[0076] A waterlogged marine wooden cultural relic specimen block was taken. The wood species was identified as Pinus. Its Fe element content was 10.5 wt%, and the S element content was 2.2 wt%. It was ground into powder, and 10 portions of 0.2 g of sample powder were weighed and placed into tea bag bags respectively;

[0077] At room temperature, the tea bag bags were immersed in the chelating agent aqueous solutions respectively, taken out after 15 days, and the contents of Fe and S elements in the solutions before and after soaking the sample powder were detected by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0078] Figure 2 For the desalination effect of HEDTA-3Na aqueous solutions with different pH values in Example 2, from Figure 2It can be seen that HEDTA-3Na aqueous solutions with pH = 5 - 9 can all remove iron sulfide compounds. As the pH value increases, the content of Fe element in the aqueous solution gradually decreases, and the content of S element gradually increases, indicating that the more acidic the chelating agent aqueous solution is, the more conducive to the dissolution of Fe element, while the more alkaline it is, the more conducive to the dissolution of S element. When pH = 6, the desalination effect of HEDTA-3Na is the best.

[0079] Figure 3 For the desalination effect of IDS-4Na aqueous solutions with different pH values in Example 2, from Figure 3 It can be seen that HEDTA-3Na aqueous solutions with pH = 5 - 9 can all remove iron sulfide compounds. When the pH is close to neutral, the dissolution effects of Fe element and S element are relatively balanced, and the desalination effect at this time is relatively good, and the neutral environment can reduce the corrosion of wood fibers by alkali.

[0080] Example 3

[0081] In this example, the concentration conditions for HEDTA-3Na and IDS-4Na to remove iron sulfide compounds were optimized:

[0082] Both HEDTA-3Na and IDS-4Na were respectively prepared into aqueous solutions with concentrations of 1 mmol / L, 5 mmol / L, 10 mmol / L, 20 mmol / L, and 30 mmol / L, with a volume of 200 mL each and a pH of 7;

[0083] A sample block of marine-exposed wooden cultural relics was taken, and the wood species was identified as Pinus. Its Fe element content was 10.5 wt%, and its S element content was 2.2 wt%. It was ground into powder, and 10 portions of 0.2 g sample powder were weighed and respectively packed into tea bags;

[0084] At room temperature, the tea bags were respectively immersed in the chelating agent aqueous solutions, taken out after 15 d, and the contents of Fe element and S element in the solution before and after soaking the sample powder were detected by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0085] Figure 4 For the desalination effect of HEDTA-3Na aqueous solutions with different concentrations in Example 3, from Figure 4 It can be seen that HEDTA-3Na aqueous solutions with concentrations of 1 - 30 mmol / L can all remove iron sulfide compounds. In the range of 1 - 20 mmol / L, the contents of Fe element and S element in the solution both increase with the increase of the concentration of the chelating agent aqueous solution. When the concentration is 20 mmol / L, the content of Fe element in the solution is about 12 mg / L, and the content of S element is about 19 mg / L. At this time, the desalination effect is the best.

[0086] Figure 5For the desalination effect of IDS-4Na aqueous solutions with different concentrations in Example 3, as can be seen from Figure 5 it, the IDS-4Na aqueous solutions with concentrations of 1-30 mmol / L can all remove iron sulfide compounds. When the concentration is 30 mmol / L, the content of Fe element in the solution is about 8.5 mg / L, and the content of S element is about 9 mg / L. The dissolution effects of Fe element and S element are relatively balanced, and the desalination effect is the best at this time.

[0087] Example 4

[0088] In this example, HEDTA-3Na and IDS-4Na were used to remove iron sulfide compounds from the marine-excavated wooden cultural relic specimen block XBJ respectively:

[0089] Prepare an aqueous solution of 5 L of 20 mmol / L HEDTA-3Na and adjust the pH = 7 with sodium hydroxide. Prepare an aqueous solution of 5 L of 30 mmol / L IDS-4Na and adjust the pH = 7 with sodium hydroxide;

[0090] Take two marine-excavated wooden cultural relic specimen blocks XBJ, the wood species is identified as a tree of the family Dipterocarpaceae, and the initial contents of Fe element and S element are shown in Table 3. At room temperature, after washing the specimen blocks with pure water to remove surface impurities, immerse them in the HEDTA-3Na aqueous solution and the IDS-4Na aqueous solution respectively, and monitor the contents of Fe element and S element in the HEDTA-3Na aqueous solution / IDS-4Na aqueous solution in real time. After 20 days, it is found that the contents of Fe element and S element no longer increase. Take out the specimen blocks, compare the appearance changes of the specimen blocks XBJ before and after treatment, and use inductively coupled plasma atomic emission spectrometry (ICP-AES) to detect the contents of Fe element and S element in the specimen blocks.

[0091] Figure 6 For the appearance comparison of the specimen block XBJ before and after treatment with the HEDTA-3Na aqueous solution in Example 4, among them, Figure 6 (a) in it is the specimen block before treatment with the HEDTA-3Na aqueous solution, Figure 6 and (b) in it is the specimen block after treatment with the HEDTA-3Na aqueous solution; Figure 7 For the appearance comparison of the specimen block XBJ before and after treatment with the IDS-4Na aqueous solution in Example 4, among them, Figure 7 and (a) in it is the specimen block before treatment with the IDS-4Na aqueous solution, Figure 7 and (b) in it is the specimen block after treatment with the IDS-4Na aqueous solution. As can be seen from Figure 6 and Figure 7It can be seen that after treatment with the aqueous solutions of HEDTA-3Na and IDS-4Na, the color of the marine-excavated wooden cultural relic specimen block XBJ became lighter, indicating that the yellowish-brown substances on the surface of the specimen block had been dissolved and removed, restoring the original morphology and color. Among them, the white substances on the surface of the specimen block were speculated to be shell calcification deposits.

[0092] Table 3 shows the data on the removal effect of HEDTA-3Na and IDS-4Na on iron sulfide compounds in marine-excavated wooden cultural relics. It can be seen from Table 3 that before the treatment with HEDTA-3Na, the contents of Fe and S elements in the XBJ specimen block were 12.5 wt% and 12.7 wt% respectively; after the treatment with HEDTA-3Na, the contents of Fe and S elements in the XBJ specimen block were 2.43 wt% and 3.69 wt% respectively, and the contents of Fe and S elements decreased by 80.56% and 70.94% respectively; after the treatment with IDS-4Na, the contents of Fe and S elements in the XBJ specimen block were 7.30 wt% and 7.79 wt% respectively, and the contents of Fe and S elements decreased by 41.60% and 38.66% respectively. It shows that both HEDTA-3Na and IDS-4Na have a certain removal effect on iron sulfide compounds in marine-excavated wooden cultural relics, and HEDTA-3Na has a better desalination ability.

[0093] Table 3 Data on the removal effect of HEDTA-3Na and IDS-4Na on iron sulfide compounds in marine-excavated wooden cultural relics

[0094] Fe element content (wt%) S element content (wt%) Before treatment 12.5 12.7 After treatment with HEDTA-3Na 2.43 3.69 After treatment with IDS-4Na 7.30 7.79

[0095] Example 5

[0096] In this example, HEDTA-3Na and IDS-4Na were used to remove iron sulfide compounds from the marine-deposited plain wooden cultural relic specimen block MS respectively:

[0097] Prepare an aqueous solution of 5 L of 20 mmol / L HEDTA-3Na and adjust the pH = 7 with sodium hydroxide. Prepare an aqueous solution of 5 L of 30 mmol / L IDS-4Na and adjust the pH = 7 with sodium hydroxide;

[0098] Take two pieces of wooden cultural relic samples MS from marine sedimentary plain. The wood species is identified as one of the hard pines in the genus Pinus. The initial contents of Fe element and S element are shown in Table 4. At room temperature, wash the sample blocks with pure water to remove surface impurities, and then immerse them in HEDTA-3Na aqueous solution and IDS-4Na aqueous solution respectively. Monitor the contents of Fe element and S element in the HEDTA-3Na aqueous solution / IDS-4Na aqueous solution in real time. After 20 days, it is found that the contents of Fe element and S element no longer increase. Take out the sample blocks, compare the appearance changes of the sample blocks MS before and after treatment, and use inductively coupled plasma atomic emission spectrometry (ICP-AES) to detect the contents of Fe element and S element in the sample blocks.

[0099] Figure 8 For the appearance comparison of the sample block MS before and after treatment with HEDTA-3Na aqueous solution in Example 5, among them, Figure 8 (a) in it is the sample block before treatment with HEDTA-3Na aqueous solution, Figure 8 (b) in it is the sample block after treatment with HEDTA-3Na aqueous solution; Figure 9 For the appearance comparison of the sample block MS before and after treatment with IDS-4Na aqueous solution in Example 5, among them, Figure 9 (a) in it is the sample block before treatment with IDS-4Na aqueous solution, Figure 9 (b) in it is the sample block after treatment with IDS-4Na aqueous solution. From Figure 8 and Figure 9 it can be seen that after treatment with HEDTA-3Na and IDS-4Na aqueous solutions, the surface of the wooden cultural relic sample block MS from the marine sedimentary plain changes from dark brown to light yellowish brown, and the color is more natural.

[0100] Table 4 shows the data of the removal effect of HEDTA-3Na and IDS-4Na on the iron sulfide compounds in the wooden cultural relics from the marine sedimentary plain. It can be seen from Table 4 that before treatment with HEDTA-3Na, the contents of Fe element and S element in the MS sample block are 1.62 wt% and 2.48 wt% respectively; after treatment with HEDTA-3Na, the contents of Fe element and S element in the MS sample block are 0.60 wt% and 1.49 wt% respectively, and the contents of Fe element and S element decrease by 62.96% and 39.92% respectively. After treatment with IDS-4Na, the contents of Fe element and S element in the MS sample block are 0.99 wt% and 1.79 wt% respectively, and the contents of Fe element and S element decrease by 38.89% and 27.82% respectively; it shows that both HEDTA-3Na and IDS-4Na have a certain removal effect on the iron sulfide compounds in the wooden cultural relics from the marine sedimentary plain, and the desalination effect of HEDTA-3Na is better.

[0101] Table 4 Desalination effect data of HEDTA-3Na and IDS-4Na on iron sulfide compounds in unearthed wooden cultural relics from marine alluvial plains

[0102] Fe element content (wt%) S element content (wt%) Before treatment 1.62 2.48 After treatment with HEDTA-3Na 0.60 1.49 After treatment with IDS-4Na 0.99 1.79

[0103] The above results show that the present invention selects trisodium hydroxyethyl ethylenediamine triacetate or tetrasodium iminodisuccinate as chelating agents, which have desalination and decolorization effects on unearthed wooden cultural relics of different wood species from marine water and high-salt strata. Compared with other chelating agents, these two chelating agents also have the characteristics of safety, environmental protection and low cost. For unearthed wooden cultural relics from different sources, the desalination ability of trisodium hydroxyethyl ethylenediamine triacetate is better than that of tetrasodium iminodisuccinate. Regarding the difference in desalination effects among unearthed wooden cultural relics from different sources, it is speculated that it is related to the deposition position of iron sulfide compounds in the wooden cultural relics. For iron sulfide compounds mainly deposited on the surface, the desalination effect is better.

Claims

1. A method for removing ferrous sulfide compounds from a wood sample, characterized in that: The following steps are involved: The wood sample is immersed in an aqueous solution of a chelating agent to remove sulfide and iron compounds; Wherein, the chelating agent is selected from trisodium hydroxyethylethylenediaminetriacetate, tetrasodium iminodisuccinate or a combination thereof.

2. The method according to claim 1, characterized in that The pH of the chelating agent aqueous solution is 5-9.

3. The method according to claim 1, characterized in that The concentration of the chelating agent aqueous solution is 1-30 mmol / L.

4. The method according to claim 3, characterized in that The solid-to-liquid ratio of the wood sample to the chelating agent aqueous solution is 1g: (1-2)L。 5. The method according to claim 3, characterized in that: The immersion time is 10-30 days.

6. Use of the method according to any one of claims 1 to 5 in the protection of wooden products.

7. The use according to claim 6, characterized in that: The wooden products include water-saturated wooden products.

8. The use according to claim 7, characterized in that: The water-saturated wooden products include wooden products that have been immersed in seawater for a long time or buried in high-salt strata for a long time.

9. The use according to claim 8, characterized in that: The wooden products soaked in seawater for a long time include wooden cultural relics recovered from the ocean; And / or, the wooden products buried in the high-salt strata for a long time include wooden cultural relics unearthed from the high-salt strata.

10. The use according to claim 8 or 9, characterized in that: In the wooden product immersed in seawater for a long time, the content of Fe element is 5wt%-15wt%, and the content of S element is 2wt%-15wt%; And / or, in the wooden product buried in the high-salt stratum for a long time, the content of Fe element is 0.5wt%-5wt%, and the content of S element is 1wt%-5wt%.

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