Modified phosphogypsum with mildew-proof and antibacterial properties and preparation method thereof

Abstract

The application discloses modified phosphogypsum with mildew-proof and antibacterial properties and a preparation method thereof, and belongs to the field of phosphogypsum mildew-proof and antibacterial treatment. The modified phosphogypsum with mildew-proof and antibacterial properties comprises the following raw materials in percentage by mass: 0.2%-0.5% of water-soluble quaternary ammonium salt bacteriostatic agent, 14%-24% of inorganic alkaline material, 46%-56% of phosphogypsum powder and 29.8%-35.8% of water; wherein the water-soluble quaternary ammonium salt bacteriostatic agent comprises 0.1%-0.3% of benzalkonium chloride and 0.1%-0.3% of cetyltrimethylammonium bromide; the inorganic alkaline material comprises 5%-20% of P.O 42.5 ordinary portland cement and 3%-9% of Ca(OH)2; the amount of the quaternary ammonium salt bacteriostatic agent and the inorganic alkaline material used for reducing the original single-doped modification to achieve the same mildew-proof effect is reduced through synergistic effect, the cost required for phosphogypsum resource treatment is reduced, and meanwhile, the optimal mildew-proof effect can be achieved without affecting the strength of the phosphogypsum.

Description

Technical Field

[0001] This invention belongs to the field of anti-mildew and antibacterial treatment of phosphogypsum, specifically relating to a modified phosphogypsum with anti-mildew and antibacterial properties and its preparation method. Background Technology

[0002] Mold growth on phosphogypsum building materials is particularly frequent in humid regions like Guizhou. This is because most phosphogypsum building materials are made directly from industrial solid waste phosphogypsum that has undergone high-temperature calcination. Under high humidity conditions, the porous phosphogypsum absorbs moisture from the air, and residual soluble phosphorus, fluorine, and other impurities create a slightly acidic environment on the surface, leading to the rapid growth and reproduction of mold. Improving the mold resistance of phosphogypsum building materials to inhibit and kill mold on their surface is a major challenge that urgently needs to be addressed in their production and application.

[0003] Currently, research on mold prevention in the construction field is not in-depth, both domestically and internationally. Methods for effectively reducing mold germination and growth in mold-resistant building materials mainly focus on designing anti-mold coatings to prevent mold colonization on building material surfaces. However, the application of anti-mold coatings has certain limitations: (1) Limited durability: Anti-mold coatings usually need to be recoated periodically because their anti-mold effect weakens over time. This means regular maintenance and recoating are required, increasing usage costs and workload; (2) Limited effectiveness: Anti-mold coatings can effectively prevent mold growth, but cannot completely eliminate existing mold. If a serious mold problem exists before coating application, relying solely on anti-mold coatings may not eradicate the root cause of the mold; (3) Impact on human health: Some anti-mold coatings may contain harmful substances, such as volatile organic compounds (VOCs), which may have a certain impact on human health. Therefore, when choosing an anti-mold coating, it is necessary to select low-VOC products and ensure good ventilation during construction; (4) Environmental impact: Some anti-mold coatings contain chemicals that may pollute the environment. These chemicals may enter the soil and water sources, causing negative impacts on the ecosystem; (5) The scope of application of anti-mold coatings is limited: anti-mold coatings are mainly applicable to indoor walls, ceilings and floors, etc. For some other special materials or scenarios, such as bathrooms, kitchens and other high humidity environments, the effect of anti-mold coatings may not be ideal; Although anti-mold coatings can prevent the growth of mold to a certain extent, there are certain shortcomings and drawbacks in terms of durability, effect, impact on human health and environment.

[0004] In addition to the above, the field of building anti-mildew can also incorporate one or more antibacterial systems into building materials. The antibacterial substances contained in these systems can be broadly classified into three categories: natural antibacterial substances, organic antibacterial substances, and inorganic antibacterial substances. Natural antibacterial substances are derived from natural plants or animals, possessing a relatively broad antibacterial spectrum and exhibiting certain inhibitory effects against various bacteria, fungi, and viruses. However, their preparation is difficult and costly, and they are easily affected by environmental and external factors, resulting in poor stability. Inorganic antibacterial substances are classified into silver-based, zinc-based, titanium-based, and copper-based substances, etc., possessing advantages such as a broad antibacterial spectrum, high safety, and long-term antibacterial properties. However, their antibacterial effect is affected by the physicochemical properties of the material, limiting their application range. Organic antibacterial substances are derived from artificial synthesis or modification, exhibiting high stability and cost-effectiveness, and have a wide range of applications, suitable for different materials and environments. However, a small portion possesses certain toxicity and hazards, and should not be used excessively. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a modified phosphogypsum with anti-mildew and antibacterial properties and its preparation method, thereby solving the problems in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A modified phosphogypsum with anti-mildew and antibacterial properties comprises the following raw materials in weight percentages: 0.2%-0.5% water-soluble quaternary ammonium salt antibacterial agent, 14%-24% inorganic alkaline material, 46%-56% phosphogypsum powder, and 29.8%-35.8% water.

[0008] Furthermore, the water-soluble quaternary ammonium salt antibacterial agent comprises: 0.1%-0.3% by mass of benzalkonium chloride and 0.1%-0.3% by mass of hexadecyltrimethylammonium bromide.

[0009] Furthermore, the inorganic alkaline material comprises: 5%-20% by mass of P·O 42.5 ordinary silicate cement and 3%-9% by mass of Ca(OH)2.

[0010] Furthermore, the pH value of the modified phosphogypsum raw materials after mixing is 12-14.

[0011] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties includes the following steps:

[0012] S1, P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder are poured into a container according to the proportion and stirred evenly;

[0013] S2, pour benzalkonium chloride and hexadecyltrimethylammonium bromide into a container filled with water and stir at a constant temperature to dissolve;

[0014] S3: First, pour the water in which benzalkonium chloride and hexadecyltrimethylammonium bromide were dissolved in S2 into a mixing container, then pour in the solid powder mixed in step S1 and let it stand. Then stir and pour it into a mold for molding.

[0015] Further, the benzalkonium chloride is 0.1%-0.3% by mass, the hexadecyltrimethylammonium bromide is 0.1%-0.3% by mass, the P·O 42.5 ordinary silicate cement is 5%-20% by mass, the Ca(OH)2 is 3%-9% by mass, the phosphogypsum powder is 46%-56% by mass, and the water is 29.8%-35.8% by mass.

[0016] Furthermore, in S1, the dry material is mechanically stirred at a rate of 1900 r / min for 2 hours in a mechanical mixer.

[0017] Further, in S2, the container is placed in a heat-collecting constant-temperature magnetic stirrer and stirred and dissolved for 20 minutes at 800 r / min and 40°C.

[0018] Furthermore, in S3, a cement paste mixer is used. The mixture is mixed at low speed for 10 seconds, then at high speed for 20 seconds, and then the mixer is turned off. The paste is poured into the mold while being slowly mixed with a mixing rod.

[0019] The above-mentioned modified phosphogypsum with anti-mildew and antibacterial properties is used in construction.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention applies quaternary ammonium salt antibacterial agents to the antifungal modification of phosphogypsum, and greatly improves the antifungal performance and antifungal durability of the modified phosphogypsum material through the synergistic effect of inorganic alkaline materials. It can also reduce the amount of quaternary ammonium salt antibacterial agents and inorganic alkaline materials required to achieve the same antifungal effect by single-component modification through synergistic effect, thereby reducing the cost required for the resource utilization of phosphogypsum. At the same time, it can achieve the optimal antifungal effect without affecting the strength of phosphogypsum.

[0022] 2. Quaternary ammonium salt antibacterial agents are used as organic antibacterial substances, which have low toxicity, high antibacterial efficiency and broad spectrum. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0024] The modification process of phosphogypsum will be described below using the following examples and comparative examples;

[0025] Example 1

[0026] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0027] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.8% water;

[0028] The preparation process is as follows:

[0029] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0030] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0031] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0032] Example 2

[0033] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0034] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.2% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.7% water;

[0035] The preparation process is the same as in Example 1.

[0036] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0037] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0038] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0039] Example 3

[0040] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0041] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.3% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.6% water;

[0042] The preparation process is the same as in Example 1.

[0043] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0044] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0045] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0046] Example 4

[0047] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0048] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.2% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.7% water;

[0049] The preparation process is the same as in Example 1.

[0050] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0051] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0052] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0053] Example 5

[0054] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0055] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.3% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.6% water;

[0056] The preparation process is the same as in Example 1.

[0057] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0058] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0059] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0060] Example 6

[0061] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0062] Take the following raw materials in the indicated weight percentages: 5% P·O 42.5 ordinary Portland cement, 3% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 56% phosphogypsum powder, and 35.8% water;

[0063] The preparation process is as follows:

[0064] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0065] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0066] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0067] Example 7

[0068] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0069] Take the following raw materials in the indicated weight percentages: 15% P·O 42.5 ordinary Portland cement, 3% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 50% phosphogypsum powder, and 31.8% water;

[0070] The preparation process is the same as in Example 6.

[0071] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0072] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0073] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0074] Example 8

[0075] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0076] Take the following raw materials in the indicated weight percentages: 20% P·O 42.5 ordinary Portland cement, 3% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 47% phosphogypsum powder, and 29.8% water;

[0077] The preparation process is the same as in Example 6.

[0078] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0079] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0080] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0081] Example 9

[0082] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0083] Take the following raw materials in the indicated weight percentages: 5% P·O 42.5 ordinary Portland cement, 9% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 52% phosphogypsum powder, and 33.8% water;

[0084] The preparation process is the same as in Example 6.

[0085] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0086] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0087] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0088] Example 10

[0089] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0090] Take the following raw materials in the indicated weight percentages: 15% P·O 42.5 ordinary Portland cement, 9% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 0.1% hexadecyltrimethylammonium bromide (CTAB), 46% phosphogypsum powder, and 29.8% water;

[0091] The preparation process is the same as in Example 6.

[0092] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0093] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0094] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0095] It is worth mentioning that the raw materials for preparing modified phosphogypsum include quaternary ammonium salt antibacterial agents and inorganic alkaline materials;

[0096] The types of antibacterial agents are not limited to benzalkonium chloride and hexadecyltrimethylammonium bromide as described in Examples 1-10. They can also be water-soluble commercial quaternary ammonium salt antibacterial agents that are widely used in the market, such as benzalkonium bromide and domiphen. Regardless of the type of water-soluble quaternary ammonium salt antibacterial agent, it can be used in conjunction with alkaline materials to improve the antifungal properties of phosphogypsum.

[0097] Furthermore, the types of inorganic alkaline materials are not limited to ordinary Portland cement (P·O 42.5) and Ca(OH)2 as described in Examples 1-5. They can also be inorganic alkaline materials such as quicklime, NaOH, or KOH. Regardless of the type of inorganic alkaline material, as long as it contains OH groups that can cause free OH groups to form in phosphogypsum, it is acceptable. - Furthermore, the pH value of the modified system can be brought to the range of 12-14 after mixing, and both can be used in this invention.

[0098] Comparative Example 1

[0099] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0100] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.1% benzalkonium chloride (BAC), 51% phosphogypsum powder, and 32.9% water;

[0101] The preparation process is as follows:

[0102] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0103] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0104] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0105] Comparative Example 2

[0106] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0107] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.2% benzalkonium chloride (BAC), 51% phosphogypsum powder, and 32.8% water;

[0108] The preparation process was the same as that of Comparative Example 1.

[0109] Comparative Example 3

[0110] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0111] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.3% benzalkonium chloride (BAC), 51% phosphogypsum powder, and 32.7% water;

[0112] The preparation process was the same as that of Comparative Example 1.

[0113] Comparative Example 4

[0114] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0115] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.4% benzalkonium chloride (BAC), 51% phosphogypsum powder, and 32.6% water;

[0116] The preparation process was the same as that of Comparative Example 1.

[0117] Comparative Example 5

[0118] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0119] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.5% benzalkonium chloride (BAC), 51% phosphogypsum powder, and 32.5% water;

[0120] The preparation process was the same as that of Comparative Example 1.

[0121] Comparative Example 6

[0122] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0123] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary Portland cement, 6% Ca(OH)2, 0.1% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.9% water;

[0124] The preparation process is as follows:

[0125] S1. First, pour P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder into a container according to the proportion, and mechanically mix the dry materials in a mechanical mixer at a rate of 1900 r / min for 2 hours.

[0126] S2. Pour the weighed benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) into a container filled with water, and place the container in a heat-collecting constant temperature magnetic stirrer. Stir and dissolve the mixture for 20 minutes at 800 r / min and 40°C.

[0127] S3. First, pour the water in which benzalkonium chloride (BAC) and hexadecyltrimethylammonium bromide (CTAB) were dissolved in step S2 into the mixing container. Then, pour in the solid powder that was mixed evenly in step S1 and let it stand for 1 minute. Then, start the cement paste mixer, mix at low speed for 10 seconds, then mix at high speed for 20 seconds and then turn off the mixer. While slowly mixing with a mixing rod, pour the slurry into a test mold of appropriate size.

[0128] Comparative Example 7

[0129] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0130] Take the following raw materials in the following weight percentages: 10% P·O 42.5 ordinary silicate cement, 6% Ca(OH)2, 0.2% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.8% water.

[0131] The preparation process was the same as that of Comparative Example 6.

[0132] Comparative Example 8

[0133] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0134] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary silicate cement, 6% Ca(OH)2, 0.3% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.7% water.

[0135] The preparation process was the same as that of Comparative Example 6.

[0136] Comparative Example 9

[0137] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0138] Take the following raw materials by weight percentage: 10% P·O 42.5 ordinary silicate cement, 6% Ca(OH)2, 0.4% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.6% water.

[0139] The preparation process was the same as that of Comparative Example 6.

[0140] Comparative Example 10

[0141] A method for preparing modified phosphogypsum with anti-mildew and antibacterial properties;

[0142] Take the following raw materials in the indicated weight percentages: 10% P·O 42.5 ordinary silicate cement, 6% Ca(OH)2, 0.5% hexadecyltrimethylammonium bromide (CTAB), 51% phosphogypsum powder, and 32.5% water.

[0143] The preparation process was the same as that of Comparative Example 6.

[0144] Below are experimental cases of anti-mold performance:

[0145] The evaluation of the anti-mildew properties of the material surface shall be carried out in accordance with the anti-mildew grade table in section 7.5 of the "Test Method for Anti-mildew Properties of Coatings" (GB / T 1741-2020).

[0146] Table 1. Mold growth and evaluation of samples

[0147] Mold growth Anti-mildew rating Anti-mold rate A (%) No growth 0 A＝100 Trace growth (moldy area <10%) 1 90＜A＜100 Small amount of growth (moldy area ≥10% and <30%) 2 70＜A≤90 Moderate growth (moldy area ≥30% and <60%) 3 40＜A≤70 Severe growth (moldy area ≥60% and ≤100%) 4 0≤A≤40

[0148] The mold species used in this study's anti-mold experiment followed the "Determination of Anti-mold Resistance of Coatings" (GB / T1741-2020), selecting *Aspergillus niger* (ATCC16404 second-generation slant culture) provided by the Shanghai Center for Biotechnology Preservation as the mold infection source. The anti-mold level was evaluated by comparing the area contaminated by *Aspergillus niger* mycelium with the total area of ​​the material tested. The experimental results of Examples 1-10 and Comparative Examples 1-10 are shown in Table 2 below:

[0149] Table 2 Results of Antifungal Grade Assessment

[0150]

[0151] According to the table above:

[0152] When the amount of inorganic alkaline material added during the modification process is consistent, the anti-mold effect of BAC or CTAB alone is not as good as that of the combination of the two. Furthermore, without changing the amount of BAC and CTAB added, changing the amount of Ca(OH)2 added is more likely to affect the anti-mold effect of the modified system than changing the amount of cement added.

[0153] In summary, compared with cement at the same dosage, Ca(OH)2 has a stronger ability to enhance the alkalinity of the system, thus more easily influencing the synergistic effect with quaternary ammonium salt antibacterial agents and resulting in a better antifungal effect. Furthermore, BAC and CTAB not only exhibit synergistic antifungal effects with inorganic alkaline materials (cement, Ca(OH)2), but as different quaternary ammonium salt antibacterial agents, they also mutually enhance each other's antifungal effects, further improving the material's antifungal efficacy.

[0154] Principle Analysis:

[0155] The synergistic effect of inorganic alkaline materials and quaternary ammonium salt antibacterial agents lies in the fact that when mold spores attach to the surface of modified PG test blocks, OH- not only denatures the proteins on the mold spores and accelerates the rate at which quaternary ammonium ions destroy the phospholipid bilayer of the cell membrane, making the mold spores more easily inactivated, but also changes the permeability of the hyphal cell membrane, affecting the metabolism of mold and thus inhibiting its growth and reproduction.

[0156] Furthermore, low-dosage quaternary ammonium salt antibacterial agents alone do not provide good antifungal effects for phosphogypsum. The antifungal effect only improves with increasing dosage; generally, a dosage of at least 0.5 wt% of quaternary ammonium salt antibacterial agent based on the total mass of phosphogypsum is required. At the same dosage of quaternary ammonium salt antibacterial agent, phosphogypsum modified systems incorporating alkaline substances achieve stronger antibacterial effects. The synergistic effect of quaternary ammonium salt antibacterial agents and alkaline materials can improve the antifungal properties and durability of modified phosphogypsum systems.

[0157] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0158] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A modified phosphogypsum with anti-mildew and antibacterial properties, characterized in that, The raw materials include the following percentages by weight: 0.2%-0.5% water-soluble quaternary ammonium salt antibacterial agent, 14%-24% inorganic alkaline material, 46%-56% phosphogypsum powder, and 29.8%-35.8% water; The water-soluble quaternary ammonium salt antibacterial agent comprises: 0.1%-0.3% by weight of benzalkonium chloride and 0.1%-0.3% by weight of hexadecyltrimethylammonium bromide; The inorganic alkaline material comprises: 5%-20% by mass of P·O 42.5 ordinary silicate cement and 3%-9% by mass of Ca(OH)2; The pH value of the modified phosphogypsum raw materials after mixing is 12-14.

2. The method for preparing modified phosphogypsum with antifungal and antibacterial properties according to claim 1, characterized in that, Includes the following steps: S1, P·O 42.5 ordinary Portland cement, Ca(OH)2 and phosphogypsum powder are poured into a container according to the proportion and stirred evenly; S2, pour benzalkonium chloride and hexadecyltrimethylammonium bromide into a container filled with water and stir at a constant temperature to dissolve; S3: First, pour the water in which benzalkonium chloride and hexadecyltrimethylammonium bromide were dissolved in S2 into a mixing container, then pour in the solid powder mixed in step S1 and let it stand. Then stir and pour it into a mold for molding.

3. The method for preparing modified phosphogypsum with antifungal and antibacterial properties according to claim 2, characterized in that, In S1, the dry material is mechanically stirred at a rate of 1900 r / min for 2 hours in a mechanical mixer.

4. The method for preparing modified phosphogypsum with antifungal and antibacterial properties according to claim 2, characterized in that, In S2, place the container in a heat-collecting, constant-temperature magnetic stirrer and stir to dissolve for 20 minutes at 800 r / min and 40°C.

5. The method for preparing modified phosphogypsum with antifungal and antibacterial properties according to claim 2, characterized in that, In S3, a cement paste mixer is used. The mixture is mixed at low speed for 10 seconds, then at high speed for 20 seconds, and then the mixer is turned off. The paste is poured into the mold while being slowly mixed with a mixing rod.

6. The application of the modified phosphogypsum with anti-mildew and antibacterial properties as described in claim 1 in the field of construction.

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