A gypsum-based antibacterial material and its preparation method and application

Abstract

The present invention discloses a gypsum-based antibacterial material, its preparation method and application. The present invention relates to the technical field of antibacterial materials. The preparation method is as follows: gypsum powder and a dispersion liquid are mixed in a certain solid-liquid ratio, and the mixture is stirred thoroughly to obtain a first slurry; a certain amount of a crystal phase converter and a crystal morphology directing agent are added to the first slurry, and the mixture is stirred and reacted for a period of time to obtain a second slurry; an antibacterial precursor is added to the second slurry, the pH value of the slurry is adjusted to acidic, and the mixture is stirred and reacted to obtain a third slurry; the third slurry is filtered, washed, dried and crushed to obtain the gypsum-based antibacterial material; the relative texture coefficient of the 204 crystal plane of the gypsum-based antibacterial material is greater than 0.1. The present invention prepares an α-CaSO4·0.5H2O material with intrinsic antibacterial activity through gypsum crystal transformation and in-situ structural regulation.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial materials, and in particular to a gypsum-based antibacterial material and a preparation method and application thereof. Background Art

[0002] By-product gypsum, as a by-product or waste residue generated in industrial production, includes desulfurized gypsum, phosphogypsum, citric acid gypsum, fluorinated gypsum, copper gypsum, titanium gypsum, etc., which has the characteristics of large quantity, complex impurity composition, and high content of harmful impurities. At present, the comprehensive utilization rate of by-product gypsum is relatively low, and it is still mainly stored, which not only wastes land resources but also causes serious pollution to the environment. In recent years, by-product gypsum has been widely used in building materials, agriculture and other fields, but it is still mainly low-value-added products. Due to the constraints of transportation distance, product stability, etc., its large-scale, high-value and bulk application is limited. Therefore, there is an urgent need to increase the added value of by-product gypsum, develop high-value products that can consume by-product gypsum in bulk, and promote the large-scale application of by-product gypsum.

[0003] Byproduct gypsum, primarily composed of CaSO4·2H2O, can be further processed to replace high-purity natural gypsum. Among gypsum and its numerous derivatives, α-CaSO4·0.5H2O exhibits significant potential in high-value-added applications such as high-end building materials, ceramics, molds, bone and wound repair, and drug delivery due to its advantages such as a complete crystal structure and low heat of hydration. This material also boasts physical strength over three times that of ordinary gypsum powder. Therefore, developing high-value-added α-CaSO4·0.5H2O products using byproduct gypsum as a raw material is an important means of overcoming the bottleneck in the large-scale consumption of byproduct gypsum.

[0004] When traditional α-CaSO4·0.5H2O materials are used in high-value-added applications such as building materials, ceramics, and molds, they exhibit a strong hydrophilicity when exposed to high humidity, which can promote bacterial growth and reproduction. The large number of bacteria present on and within the surface of the α-CaSO4·0.5H2O material poses a serious threat to public safety. For example, when used in high-end building materials, α-CaSO4·0.5H2O can indirectly increase the incidence of respiratory infections such as asthma. When used in high-value medical bandages, bacteria attached to the surface can cause wound infections due to their close proximity to wounds. Therefore, developing α-CaSO4·0.5H2O materials with excellent antibacterial properties is crucial for improving people's living environments, reducing the risk of bacterial infection, and further promoting the large-scale application of α-CaSO4·0.5H2O materials.

[0005] Currently, some research on the antibacterial α-CaSO4·0.5H2O material has focused on imparting antimicrobial properties by physically mixing various antimicrobial agents with it. This process causes the antimicrobial agent to agglomerate, significantly reducing its bactericidal properties and typically requiring an increased dosage to meet antimicrobial requirements. Furthermore, physical mixing of the α-CaSO4·0.5H2O material with the antimicrobial agent creates a physical barrier between the antimicrobial agent and bacteria, hindering direct contact between the agent and bacteria and severely degrading its antimicrobial properties. Summary of the Invention

[0006] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a gypsum-based antibacterial material and a preparation method and application thereof.

[0007] A method for preparing a gypsum-based antibacterial material of the present invention comprises the following steps:

[0008] Step S1, crushing gypsum ore or by-product gypsum into gypsum powder;

[0009] Step S2, mixing the gypsum powder obtained in step S1 with the dispersion at a certain solid-liquid ratio, and stirring thoroughly to obtain a first slurry;

[0010] Step S3, adding a certain amount of crystal phase conversion agent and crystal morphology directing agent to the first slurry obtained in step S2, stirring and reacting for a period of time to obtain a second slurry;

[0011] Step S4, adding an antibacterial precursor to the second slurry obtained in step S3, adjusting the pH value of the slurry to acidic, and stirring the mixture to obtain a third slurry;

[0012] Step S5, filtering, washing, drying, and crushing the third slurry in step S4 to obtain the gypsum-based antibacterial material;

[0013] The relative texture coefficient of the 204 crystal plane of the gypsum-based antibacterial material is greater than 0.1.

[0014] Furthermore, in step S3, the phase transition agent is one or more of sodium salt, calcium salt, potassium salt, and magnesium salt; and\or,

[0015] The anion in the salt is one of sulfate ion, chloride ion, nitrate ion and acetate ion; and\or,

[0016] The mass ratio of the phase transition agent to the by-product gypsum powder is 0.01 to 100:100.

[0017] Furthermore, in step S3, the crystal morphology directing agent is one or more of sodium tartrate, succinic acid, sodium citrate, malic acid, sodium lauryl sulfate, hexadecyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate; and\or,

[0018] The mass ratio of the crystal morphology directing agent to the by-product gypsum powder is 0.01 to 100:100.

[0019] Furthermore, in step S3, the stirring reaction temperature is 10 to 200° C. and the time is 0.1 to 24 h.

[0020] Furthermore, in step S1, the by-product gypsum includes one or more of desulfurized gypsum, phosphogypsum, citric acid gypsum, fluorinated gypsum, copper gypsum and titanium gypsum; and\or,

[0021] In step S2, the dispersion liquid is one or more of water, ethanol, methanol, formic acid, n-hexane, ammonium sulfate solution, ammonium nitrate solution, and ammonium carbonate solution; and\or,

[0022] The mass volume ratio of the gypsum powder to the dispersion is 1:1 to 100 g / mL.

[0023] Furthermore, in step S4, the antibacterial precursor is one or more of cerium salt, zinc salt, magnesium salt, gallium salt, silver salt, manganese salt, copper salt, and iron salt; and\or,

[0024] The anion in the salt is one of sulfate ion, chloride ion, nitrate ion and acetate ion; and\or,

[0025] The mass ratio of the antibacterial precursor to the gypsum powder is 0.01 to 100:100.

[0026] Furthermore, in step S4, the pH adjuster is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, sodium hydroxide, sodium dihydrogen phosphate, and Tris-buffer.

[0027] Furthermore, in step S4, the stirring reaction temperature is 10 to 200° C. and the time is 0.1 to 24 h; and\or,

[0028] In step S5, the drying temperature is 40-200° C. and the crushing time is 0.1-1 h.

[0029] A gypsum-based antibacterial material prepared by the above-mentioned preparation method.

[0030] An application of the gypsum-based antibacterial material as described above is used in high-end building materials, ceramics, molds, bandages, and bone / wound repair drugs.

[0031] Beneficial effects of the present invention:

[0032] (1) The gypsum crystallization technology provided by the present invention for preparing antibacterial gypsum materials has mild reaction conditions, low cost, simple and easy technology, controllable crystal form, high yield, and high-purity product, which significantly reduces the cost of preparing α-CaSO4·0.5H2O using by-product gypsum.

[0033] (2) The high-value-added gypsum-based antibacterial material provided by the present invention has intrinsic antibacterial activity; the present invention improves the relative texture coefficient of the 204 face of the α-CaSO4·0.5H2O crystal and the intrinsic antibacterial activity of the α-CaSO4·0.5H2O material by regulating the crystal plane during the process of preparing the α-CaSO4·0.5H2O material by crystallization of natural gypsum or by-product gypsum, and the antibacterial component in the gypsum-based antibacterial material is coordinated and bonded with α-CaSO4·0.5H2O, which significantly improves the antibacterial activity of the antibacterial component and can simultaneously achieve efficient disinfection of Gram-negative bacteria and Gram-positive bacteria, with an antibacterial rate of >99%, meeting the national Class I antibacterial standard.

[0034] (3) The α-CaSO4·0.5H2O in the gypsum-based antibacterial material provided by the present invention improves the release rate of the antibacterial components and accelerates the disinfecting of bacteria. The gypsum-based antibacterial material provided by the present invention has a low content of active antibacterial components but excellent antibacterial properties. Compared with traditional physically mixed antibacterial materials, the amount of antibacterial components added is significantly reduced, and the production and application costs of the antibacterial materials are significantly reduced.

[0035] (4) The gypsum-based antibacterial material provided by the present invention, when used for sterilization, releases less metal ions, has high stability, low biological toxicity, exhibits excellent antibacterial efficacy, is simple to operate, low in cost, safe and reliable, has certain biological characteristics and biological functions, and increases the added value of natural gypsum and by-product gypsum products. It can be promoted and applied in high-end building materials, ceramics, molds, bandages, bone / wound repair and other fields, significantly increases the added value of natural gypsum and by-product gypsum, promotes the resource utilization of natural gypsum and by-product gypsum, and can effectively save resources and protect the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figures 1a to 1d These are the X-ray diffraction patterns of the antibacterial materials HH-2, HH-3, HH-4 and HH-1;

[0037] Figure 2a This is the SEM image of HH-4 antibacterial material;

[0038] Figure 2b This is the SEM image of HH-1 antibacterial material;

[0039] Figure 3a This is the TEM spectrum of HH-4 antibacterial material;

[0040] Figure 3bThis is the TEM spectrum of HH-1 antibacterial material;

[0041] Figure 4 This is the antibacterial effect diagram of HH-2 antibacterial material on Staphylococcus aureus (S. aureus);

[0042] Figure 5 This is the antibacterial effect diagram of HH-3 antibacterial material on Staphylococcus aureus (S. aureus);

[0043] Figure 6 This is the antibacterial effect diagram of HH-4 antibacterial material on Staphylococcus aureus (S. aureus);

[0044] Figure 7 This is the antibacterial effect diagram of HH-4 antibacterial material on Escherichia coli (E.coli);

[0045] Figure 8 This is the antibacterial effect diagram of HH-1 antibacterial material on Staphylococcus aureus (S. aureus);

[0046] Figure 9 This is the antibacterial effect diagram of HH-1 antibacterial material on Escherichia coli (E.coli). DETAILED DESCRIPTION

[0047] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0048] Example 1

[0049] The crushed phosphogypsum powder was mixed with water in a mass-to-volume ratio of 1:10 (g:mL) to form a slurry. After thorough stirring, a certain mass of potassium sulfate and sodium citrate were added, wherein the mass ratios of potassium sulfate, sodium citrate to phosphogypsum powder were 1:3 and 1:10, respectively, and the mixture was stirred at 100°C for 6 hours; a certain mass of copper nitrate was added, wherein the mass ratio of copper sulfate to phosphogypsum powder was 1:50, the reaction pH was adjusted to 7, and the mixture was stirred at 100°C for 2 hours; after the reaction was completed, the mixture was filtered, washed, and dried at 70°C to obtain a doped powder filter cake, which was then ground to obtain a phosphogypsum-based antibacterial material, labeled HH-1.

[0050] Comparative Example 1

[0051] The crushed phosphogypsum powder was mixed with water in a mass-to-volume ratio of 1:10 (g:mL) to form a slurry. After sufficient stirring, a certain mass of sodium sulfate and sodium tartrate were added, wherein the mass ratios of sodium sulfate and sodium tartrate to phosphogypsum powder were 1:5 and 1:10, respectively, and the mixture was stirred at 95°C for 6 hours; a certain mass of zinc sulfate was added, wherein the mass ratio of zinc sulfate to phosphogypsum powder was 1:20, the reaction pH was adjusted to 2, and the mixture was stirred at 95°C for 1 hour; after the reaction was completed, the mixture was filtered, washed, and dried at 70°C to obtain a doped powder filter cake, which was then ground to obtain a phosphogypsum-based antibacterial material, labeled HH-2.

[0052] Comparative Example 2

[0053] The crushed fluorgypsum powder was mixed with n-hexane in a mass-to-volume ratio of 1:30 (g:mL) to form a slurry. After sufficient stirring, a certain mass of sodium chloride and succinic acid were added, wherein the mass ratios of sodium chloride, succinic acid and fluorgypsum powder were 1:50 and 1:25, respectively, and the mixture was stirred at 120°C for 6 hours; a certain mass of cerium nitrate was added, wherein the mass ratio of cerium nitrate to phosphogypsum powder was 1:50, the reaction pH was adjusted to 5, and the mixture was stirred at 100°C for 3 hours; after the reaction was completed, the mixture was filtered, washed, and dried at 70°C to obtain a doped powder filter cake, which was then ground to obtain a phosphogypsum-based antibacterial material labeled HH-3.

[0054] Comparative Example 3

[0055] The crushed phosphogypsum powder was mixed with water in a mass-to-volume ratio of 1:4 (g:mL) to form a slurry. After sufficient stirring, a certain mass of sodium sulfate and succinic acid were added, wherein the mass ratios of sodium sulfate, succinic acid and phosphogypsum powder were 1:5 and 1:8, respectively, and the mixture was stirred at 90°C for 4 hours; a certain mass of copper nitrate was added, wherein the mass ratio of copper nitrate to phosphogypsum powder was 1:10, the reaction pH was adjusted to 3, and the mixture was stirred at 100°C for 1 hour; after the reaction was completed, the mixture was filtered, washed, and dried at 70°C to obtain a doped powder filter cake, which was then ground to obtain a phosphogypsum-based antibacterial material, labeled HH-4.

[0056] Antibacterial performance test of by-product gypsum-based antibacterial materials

[0057] (1) Antibacterial test against Staphylococcus aureus (S. aureus)

[0058] In this embodiment, antibacterial experiments on Staphylococcus aureus (S. aureus) were conducted using HH-1, HH-2, HH-3, HH-4 and HH-1 antibacterial materials.

[0059] The bacterial activation process is as follows: First, remove the stored Staphylococcus aureus and place it in a biosafety cabinet. Then, use an inoculating loop to add one colony to 5 mL of liquid culture medium and incubate in a constant temperature shaker for 12 hours at 180 rpm and 37°C.

[0060] Next, dilute the bacterial suspension (S. aureus): Label the 12-hour resuscitation suspension as No. 0. Remove four 1.5 mL sterile centrifuge tubes and label them No. 1, No. 2, No. 3, and No. 4. Add 900 μL of LB liquid medium to sterile centrifuge tube No. 1. Add 100 μL of the 12-hour resuscitation suspension to centrifuge tube No. 1. Mix thoroughly with a pipette. Remove 100 μL and add it to centrifuge tube No. 2, continue mixing. Repeat this process until the suspension is diluted to centrifuge tube No. 4, for a dilution factor of 10,000.

[0061] Next is the addition of materials: prepare 6 50mL sterile centrifuge tubes and mark them. Among them, no antibacterial materials are added to the control centrifuge tube, and only 10mL of LB culture medium is added. The remaining centrifuge tubes are added with 10mg of HH-2 antibacterial material, 10mg of HH-3 antibacterial material, 10mg of HH-4 antibacterial material, 10mg of HH-1 antibacterial material and 10mL of LB culture medium as experimental groups. Then take 100μL of the 10,000-fold diluted bacterial solution and add it to the control and experimental group centrifuge tubes respectively, and culture in a constant temperature shaker at 37°C for 4 hours.

[0062] Next, perform plate plating: Sterilize the prepared culture dishes, place them in a safety cabinet, and label them. Remove 50 μL of the bacterial solution from the control and experimental groups, cultured for 4 hours, and drip it onto the culture dishes. Add four sterile glass beads and roll for 2 minutes in each direction. Spread three culture dishes for each sample as a parallel group. Finally, place the coated culture dishes in a 37°C incubator and incubate overnight.

[0063] Finally, plate counts were performed and photos were taken to calculate the antibacterial rates of different samples and compare their antibacterial properties. All experimental operations were performed in a biological safety cabinet.

[0064] (2) Antibacterial test on Escherichia coli (E. coli)

[0065] In this embodiment, the antibacterial materials HH-4 and HH-1 were used to conduct antibacterial experiments on Escherichia coli (E. coli).

[0066] (1) First, remove the stored E. coli and place it in a biosafety cabinet. Then, use an inoculating loop to pick up a colony and add it to 5 mL of liquid culture medium. Incubate in a constant temperature shaker for 12 hours at a speed of 180 rpm and a temperature of 37°C.

[0067] (2) Mark the bacterial solution that has been revived for 12 hours as No. 0, and then take out four 1.5 mL sterile centrifuge tubes and mark them as No. 1, No. 2, No. 3, and No. 4. Add 900 μL of LB liquid culture medium to sterile centrifuge tube No. 1, take 100 μL of the bacterial solution that has been activated for 12 hours to the 1.5 mL centrifuge tube, mix it evenly with a pipette, take out 100 μL and transfer it to centrifuge tube No. 2 and continue mixing evenly, perform gradient dilution, and dilute it to centrifuge tube No. 4 in the same way, with a dilution factor of 10,000 times.

[0068] (3) Prepare three 50 mL sterile centrifuge tubes and label them. The control centrifuge tube does not contain any antimicrobial material, but only contains 10 mL of LB culture medium. Each of the remaining centrifuge tubes contains 10 mg of HH-4 antimicrobial material, 10 mg of HH-1 antimicrobial material, and 10 mL of LB culture medium, serving as the experimental group. Then, take 100 μL of the 10,000-fold diluted bacterial solution and add it to the control and experimental tubes, respectively. Incubate in a 37°C constant temperature shaker for 4 hours.

[0069] (4) Place the prepared culture dishes in a safety cabinet and label them. Take out 50 μL of the bacterial solution from the control group and the experimental group after 4 hours of culture and drip it into the culture dishes. Then add 4 sterile glass beads and roll in each direction for 2 minutes. Coat 3 culture dishes for each sample as a parallel group. Finally, place the coated culture dishes in a 37℃ constant temperature incubator and culture for 15 hours.

[0070] (5) Finally, plate counts were performed and photographs were taken to calculate the antibacterial rates of different antibacterial materials and compare their antibacterial properties. All antibacterial experiments were conducted in a biosafety cabinet in the microbiology laboratory.

[0071] Figures 1a to 1d These are the X-ray diffraction patterns of the antibacterial materials HH-2, HH-3, HH-4 and HH-1. It can be seen from the figure that the main phase in the material is α-CaSO4·0.5H2O, and the characteristic peak of the α-CaSO4·0.5H2O phase is sharp and has high intensity, indicating that the synthesized hemihydrate gypsum has good crystallinity and high crystal order.

[0072] Table 1 shows the relative texture coefficients of the antibacterial materials HH-2, HH-3, HH-4 and HH-1. It can be seen from the table that the relative texture coefficient of the (204) crystal plane of the HH-1 sample is significantly higher than that of the other samples, indicating that the degree of orientation of the (204) crystal plane of the HH-1 sample is significantly higher than that of the other samples.

[0073] Table 1

[0074]

[0075] Figure 2aThis is the SEM image of the HH-4 antibacterial material. It can be observed that the material is mainly a rod-like structure with a length of about 12-40μm and a diameter of 1-3μm; among them, the relative texture coefficient of the 204 crystal plane is 0.075.

[0076] Figure 2b This is the SEM image of the HH-1 antibacterial material. It can be observed that the material is mainly a regular hexagonal prism structure with a regular hexagonal side length of about 8μm; among them, the relative texture coefficient of the 204 crystal plane is 0.551.

[0077] Figure 3a This is a TEM image of the HH-4 antibacterial material. It can be observed that the material also has a rod-like structure, approximately 18 μm in length and 1 μm in diameter. The 400 crystal plane is the side of the rod-like structure, and the 204 crystal plane is the end face of the rod-like structure.

[0078] Figure 3b This is a TEM image of the HH-1 antibacterial material. It can be observed that the material is primarily composed of a regular hexagonal prism structure with a side length of approximately 8 μm. The 204 crystal planes form the top and bottom surfaces of the regular hexagonal prism structure, while the 400 crystal planes form the side surfaces.

[0079] Figure 4 This is the antibacterial effect diagram of HH-2 antibacterial material on Staphylococcus aureus (S. aureus). It can be observed from the figure that the antibacterial effect of the HH-2 sample is poor.

[0080] Figure 5 This is the antibacterial effect diagram of HH-3 antibacterial material on Staphylococcus aureus (S. aureus). It can be observed from the figure that the antibacterial effect of the HH-3 sample is obvious, and the antibacterial rate is about 50%.

[0081] Figure 6 This is the antibacterial effect diagram of HH-4 antibacterial material on Staphylococcus aureus (S. aureus). It can be observed from the figure that the antibacterial effect of the HH-4 sample is obvious, and the antibacterial rate is about 50%.

[0082] Figure 7 This is the antibacterial effect diagram of HH-4 antibacterial material on Escherichia coli (E. coli). It can be observed from the figure that the antibacterial effect of the HH-4 sample is obvious, and the antibacterial rate is about 80%.

[0083] Figure 8 This is the antibacterial effect diagram of HH-1 antibacterial material on Staphylococcus aureus (S. aureus). It can be observed from the figure that the antibacterial effect of the HH-1 sample is obvious, and the antibacterial rate is about 80%.

[0084] Figure 9This is the antibacterial effect diagram of HH-1 antibacterial material on Escherichia coli (E. coli). It can be seen from the figure that the antibacterial effect of the HH-1 sample is obvious, the antibacterial rate is greater than 99%, and it meets the national Class I antibacterial standard.

[0085] Any matters not mentioned above shall be subject to the existing technology.

[0086] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a gypsum-based antibacterial material, characterized in that: The steps include: The crushed phosphogypsum powder was mixed with water at a mass volume ratio of 1 g:10 mL to form a slurry. After thorough stirring, a certain mass of potassium sulfate and sodium citrate were added, where the mass ratios of potassium sulfate, sodium citrate to phosphogypsum powder were 1:3 and 1:10, respectively, and the mixture was stirred at 100°C for 6 h. A certain mass of copper nitrate was added, where the mass ratio of copper sulfate to phosphogypsum powder was 1:50, the reaction pH was adjusted to 7, and the mixture was stirred at 100°C for 2 h. After the reaction was completed, the mixture was filtered, washed, and dried at 70°C to obtain a doped powder filter cake, which was then ground to obtain a phosphogypsum-based antibacterial material.

2. The method for preparing a gypsum-based antibacterial material according to claim 1, wherein: The regulator for adjusting the pH value of the reaction is one or more of hydrochloric acid, sulfuric acid, phosphoric acid, sodium hydroxide, sodium dihydrogen phosphate, and Tris-buffer.

3. A gypsum-based antibacterial material prepared by the preparation method according to claim 1 or 2.

4. An application of the gypsum-based antibacterial material according to claim 3, characterized in that: Used in high-end building materials, ceramics, molds, bandages, and bone / wound repair drugs.

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