Aluminum phosphate modified hydroxyapatite materials and their preparation methods

Abstract

This invention relates to the field of hydroxyapatite technology and discloses aluminum phosphate-modified hydroxyapatite material and its preparation method, comprising the following materials: 1.32g diammonium hydrogen phosphate, 1.33g aluminum chloride, simulated weathering sample, and 200ml deionized water. The modified hydroxyapatite prepared by this invention, by adding an aluminum source during the original protection process, effectively improves the porosity, ultrasonic velocity, and strength of the weathered sample while ensuring aesthetic compatibility. Furthermore, its acid resistance is also improved, effectively enhancing the acid rain resistance of outdoor carbonate rock artifacts.

Description

Technical Field

[0001] This invention relates to the field of hydroxyapatite technology, specifically to aluminum phosphate modified hydroxyapatite materials and their preparation methods. Background Technology

[0002] Hydroxyapatite, also known as hydroxyapatite, is chemically stable. In nature, other calcium phosphate minerals tend to spontaneously transform into hydroxyapatite. Hydroxyapatite has extremely low solubility, essentially making it insoluble and unaffected by natural precipitation. It also exhibits excellent acid resistance, remaining stable in environments with a pH > 4.0. This property protects it from erosion by acidic pollutants such as carbon dioxide, sulfur oxides, and nitrogen oxides in the air. Furthermore, hydroxyapatite possesses moderate mechanical strength and good cementing properties. These properties give it a natural advantage as a material for cultural relic preservation. In recent years, hydroxyapatite has gradually attracted the attention of cultural relic preservationists and has begun to be increasingly studied and applied in the reinforcement and preservation of various cultural relics, including marble, limestone, calcareous sandstone, and oracle bones.

[0003] While hydroxyapatite is an excellent protective material for carbonate rocks with superior acid resistance, its significantly different cell parameters compared to calcite lead to uneven film formation. In contrast, aluminum phosphate, belonging to the hexagonal crystal system, exhibits cell parameters in the a and b directions of the Lab color space that are remarkably similar to calcite, differing only slightly. The solubility product of this substance is approximately 6.3 × 10⁻⁶ at 25°C. -19 It has a much smaller solubility product than calcite and exhibits excellent corrosion resistance.

[0004] Therefore, in response to the problems of hydroxyapatite mentioned above, this study added an aluminum source to the original protection process to prepare a carbonate rock protection material with better corrosion resistance. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, the modified hydroxyapatite prepared in this invention, by adding an aluminum source during the original protection process, effectively improves the porosity, ultrasonic velocity, and strength of weathered samples while ensuring aesthetic compatibility. In addition, its acid resistance is also improved, effectively enhancing the acid rain resistance of outdoor carbonate rock artifacts. This solves the problem that although hydroxyapatite is a very good carbonate rock protection material with excellent acid resistance, its cell parameters differ greatly from those of calcite, resulting in uneven film formation.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: aluminum phosphate modified hydroxyapatite material, wherein the material contains 0.9wt% to 2.5wt% aluminum and 1.1wt% to 4.9wt% phosphorus, and the phosphorus-aluminum ratio is 1.22-1.96.

[0009] The present invention also provides a method for preparing aluminum phosphate modified hydroxyapatite material, comprising the following materials: 1.32g diammonium hydrogen phosphate, 1.33g aluminum chloride, simulated weathering sample and 200ml deionized water;

[0010] It also includes the following specific preparation steps:

[0011] S1. Mix 1.32g of diammonium hydrogen phosphate with 100ml of deionized water to obtain a 0.1mol / L diammonium hydrogen phosphate solution. Add the diammonium hydrogen phosphate solution dropwise to the simulated weathering sample to obtain a weathering sample with a phosphorus source for later use.

[0012] S2. Mix 1.33g of aluminum chloride with 100ml of deionized water to obtain a 0.1mol / L aluminum chloride solution. Then, add the aluminum chloride solution dropwise to the weathered sample with phosphorus source prepared in S1 to obtain a weathered sample with both phosphorus and aluminum sources for later use.

[0013] S3. The 0.1 mol / L diammonium hydrogen phosphate solution prepared in S1 is added dropwise to the weathered sample containing phosphorus and aluminum sources to obtain aluminum phosphate modified hydroxyapatite material, which is designated as PN0.1-Al.

[0014] Preferably, the concentration of the diammonium hydrogen phosphate solution prepared in step S1 is 0.1 mol / L, and the concentration of the aluminum chloride solution prepared in step S2 is 0.1 mol / L.

[0015] Preferably, the amount of diammonium hydrogen phosphate solution added in step S1 is 5 ml, the amount of aluminum chloride solution added in step S2 is 1 ml, the amount of diammonium hydrogen phosphate solution added in step S3 is 1 ml, and the size of the simulated weathering sample in step S1 is 2*2*1 cm.

[0016] (III) Beneficial Effects

[0017] Compared with the prior art, the present invention provides aluminum phosphate modified hydroxyapatite material and its preparation method, which has the following beneficial effects:

[0018] The modified hydroxyapatite prepared in this invention, by adding an aluminum source in the original protection process, effectively improves the porosity, ultrasonic velocity, and strength of weathered samples while ensuring aesthetic compatibility. In addition, its acid resistance is also improved, which can effectively enhance the acid rain resistance of outdoor carbonate rock artifacts. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the preparation method for aluminum phosphate modified hydroxyapatite material proposed in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1:

[0022] Please see Figure 1 Aluminum phosphate modified hydroxyapatite material and its preparation method, including the following materials: 1.32g diammonium hydrogen phosphate, 1.33g aluminum chloride, simulated weathering sample and 200ml deionized water;

[0023] It also includes the following specific preparation steps:

[0024] S1. Mix 1.32g of diammonium hydrogen phosphate with 100ml of deionized water to obtain a 0.1mol / L diammonium hydrogen phosphate solution. Add 5ml of the diammonium hydrogen phosphate solution dropwise into a simulated weathering sample with dimensions of 2*2*1cm to obtain a weathering sample with a phosphorus source for later use.

[0025] S2. Mix 1.33g of aluminum chloride with 100ml of deionized water to obtain a 0.1mol / L aluminum chloride solution. Then, add 1ml of the aluminum chloride solution dropwise to the weathered sample with phosphorus source prepared in S1 to obtain a weathered sample with both phosphorus and aluminum sources for later use.

[0026] S3. Add 1 ml of diammonium hydrogen phosphate solution prepared in S1 to the weathered sample containing phosphorus and aluminum sources to obtain aluminum phosphate modified hydroxyapatite material, and label the aluminum phosphate modified hydroxyapatite material as PN0.1-Al.

[0027] The prepared PN0.1-Al was subjected to colorimetric and color difference tests, as shown below:

[0028] A portable colorimeter was used to test and record the L, a, and b values ​​of the sample surface. The CI E1976 color difference formula and its color development system CI ELAB are used to measure the color space of an object. The color difference ΔE between two colors is the geometric distance between two locations in the CI E1976 (L, a, b) color space, calculated using the following formula:

[0029] ΔE=[(ΔL) 2 +(Δa) 2 +(Δb) 2 ] 1 / 2

[0030] In the formula, △L = Lsample - Lstandard; △a = asample - astandard; △b = bsample - bstandard.

[0031] ΔE is used to evaluate color difference. A smaller ΔE value indicates a smaller color difference. During the experiment, 5 points were randomly selected from the sample for testing, and the average value was taken for analysis. The experimental results are shown in Table 1. According to the acceptable color difference range for cultural relic protection, ΔE is less than 5. The color difference of this material applied to carbonate rock is much smaller than the standard value.

[0032] Table 1. Colorimetric and color difference data of the experimental samples

[0033]

[0034] UT serves as the experimental control group, i.e., hydroxyapatite without the addition of an aluminum source.

[0035] Example 2:

[0036] Based on Example 1, the apparent porosity of the test sample PN0.1-Al was measured:

[0037] Before the test, clean the sample surface and dry it in an electric drying oven at 105℃ until constant weight. The difference between two consecutive weighings 1 hour apart should be less than 0.1%. Before weighing, place the sample in a desiccator to cool to room temperature. Weigh to an accuracy of 0.01g, and record as m1. Place the constant-weighted sample in a tray, add water to cover the sample, and then place it in a vacuum drying oven. Turn on the vacuum pump and evacuate until the residual pressure is less than 0.0013MPa, maintain this pressure for 10 minutes, and then evacuate until no air bubbles appear on the sample. Open the vacuum drying oven, wipe the sample dry, and weigh it to an accuracy of 0.01g, recording as m2. Weigh the sample in water to an accuracy of 0.01g, recording as m3. Then, calculate the apparent porosity of the experimental sample using the following formula:

[0038]

[0039]

[0040] In the formula, q is the apparent porosity of the sample; Dv is the bulk density of the sample.

[0041] The test results are shown in Table 2. The apparent porosity decreased by 20.29%, effectively reducing porosity.

[0042] Table 2. Apparent porosity and change rate of experimental samples

[0043]

[0044] Example 3:

[0045] Based on Example 1, ultrasonic non-destructive testing was performed on the test sample PN0.1-Al:

[0046] The non-metallic ultrasonic testing instrument was used to perform ultrasonic non-destructive testing on the sample. The measurement mode was adopted. Due to the non-uniformity inside the rock sample, in order to reduce the error caused by different test positions, the principle of "fixed point test" should be followed when testing the ultrasonic wave velocity. That is, when testing the same sample at different times, the position of contact with the probe should be kept consistent, and the average value of 5 measurement results should be taken.

[0047] The test results are shown in Table 3. Compared with the control group of 13.87 km / s, the ultrasonic speed of the sample with added material reached 27.94 km / s, an increase of 101.14%.

[0048] Table 3. Ultrasonic velocity and rate of change of the experimental sample.

[0049]

[0050] Example 4:

[0051] Based on Example 1, an acid resistance test was conducted on the test sample PN0.1-Al:

[0052] After drying the sample, weigh it and record its surface morphology. Prepare an acidic solution with pH=3.5 using concentrated sulfuric acid and concentrated nitric acid in a molar ratio of 1:1. Place the sample in the acidic solution and put it in an ultrasonic cleaner at 40 kHz for 5 hours. Remove the sample and wash it with ultrapure water. Then dry it at 55℃ for 18 hours and weigh it. This is one cycle. After ten cycles, test the sample mass.

[0053] The results are shown in Table 4 below. After 10 cycles, compared with the control group, the mass loss rate was 2.10%, and the mass loss rate of the sample with added material was 1.23%, with an acid resistance of 41.48%.

[0054] Table 1. Mass loss rate and inhibition rate of the sample after 10 acid-resistant cycles.

[0055]

[0056] In summary, through the comparison of Examples 1-5, this material effectively improves the porosity and ultrasonic velocity of weathered samples while ensuring aesthetic compatibility, effectively enhances the strength of weathered samples, and also improves its acid resistance, thus effectively improving the acid rain resistance of outdoor carbonate rock artifacts.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An aluminium phosphate-modified hydroxyapatite material characterised in that: The material contains 0.9 wt% to 2.5 wt% aluminum and 1.1 wt% to 4.9 wt% phosphorus, with a phosphorus-aluminum ratio of 1.22-1.96; The preparation method of the aluminum phosphate modified hydroxyapatite material includes the following specific preparation steps: S1: Mix 1.32g of diammonium hydrogen phosphate with 100ml of deionized water to obtain a 0.1mol / L diammonium hydrogen phosphate solution. Add the diammonium hydrogen phosphate solution dropwise to the simulated weathering sample to obtain a weathering sample with a phosphorus source for later use. S2: Mix 1.33g of aluminum chloride with 100ml of deionized water to obtain a 0.1mol / L aluminum chloride solution. Then, add the aluminum chloride solution dropwise to the weathered sample with phosphorus source prepared in S1 to obtain a weathered sample with both phosphorus and aluminum sources for later use. S3: The 0.1 mol / L diammonium hydrogen phosphate solution prepared in S1 is added dropwise to the weathered sample containing phosphorus and aluminum sources to obtain aluminum phosphate modified hydroxyapatite material, which is designated as PN0.1-Al.

2. The aluminum phosphate modified hydroxyapatite material according to claim 1, characterized in that: The amount of diammonium hydrogen phosphate solution added in S1 is 5 ml.

3. The aluminum phosphate modified hydroxyapatite material according to claim 1, characterized in that: The amount of aluminum chloride solution added in S2 is 1 ml.

4. The aluminum phosphate modified hydroxyapatite material according to claim 1, characterized in that: The amount of diammonium hydrogen phosphate solution added in S3 is 1 ml.

5. The aluminum phosphate modified hydroxyapatite material according to claim 1, characterized in that: The simulated weathering sample in S1 has a size of 2*2*1cm.

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