Non-oxidizing bactericide for industrial circulating water and preparation method thereof

Abstract

The application discloses a non-oxidizing bactericide for industrial circulating water and a preparation method thereof, and belongs to the technical field of industrial water treatment. The bactericide comprises degradable double-cation quaternary ammonium salt compounds 8.0%-12.0%, double-chain quaternary ammonium salt 5.0%-8.0%, natural composite plant extract 3.0%-6.0%, cosolvent 2.0%-4.0%, chelating agent 0.5%-1.0%, and the rest is deionized water; wherein the natural composite plant extract is a composite ethanol extract of mangosteen peel and henna seeds. The application constructs a three-dimensional synergistic system of "spreading penetration-powerful killing-multiple target resistance inhibition" through scientific compounding of three types of core components, and has the properties of high-efficiency broad-spectrum bactericidal, excellent biofilm stripping, strong drug resistance and green environmental protection, with a 28-day biological degradation rate of greater than or equal to 90%. Meanwhile, the preparation method is simple and controllable, has no toxic by-products, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of industrial water treatment technology, and in particular to a non-oxidizing bactericide for industrial circulating water and its preparation method. Background Technology

[0002] Industrial circulating cooling water systems are core supporting units for production and operation in industries such as petrochemicals, steel, power, and chemicals. The suitable temperature and nutrient environment within the system can easily lead to the proliferation of bacteria and algae, forming a dense biofilm, which in turn causes problems such as equipment corrosion, pipe scaling, and a significant decrease in heat exchange efficiency. In severe cases, it can even cause safety accidents. Therefore, the addition of bactericides is one of the core aspects of circulating water treatment.

[0003] Currently, the non-oxidizing bactericides commonly used in industrial circulating water systems are mainly single-chain quaternary ammonium salts (such as dodecyl dimethyl benzyl ammonium chloride) and isothiazolinones. Among them, single-chain quaternary ammonium salts have the disadvantages of low surface activity, poor biofilm penetration, and easy development of serious drug resistance with long-term use; isothiazolinone bactericides are irritating, easily decompose and become ineffective, and pose environmental risks, thus failing to meet the current requirements for the development of green chemical industry.

[0004] Existing technologies also employ quaternary ammonium salt compounding schemes to enhance bactericidal effects, but these are mostly simple combinations of different single-chain quaternary ammonium salts. They only achieve the synergistic effect of a single bactericidal pathway and cannot fundamentally solve the problem of drug resistance. Furthermore, their effectiveness against stubborn bacteria within biofilms is limited. While some plant-derived fungicides possess environmentally friendly properties, their use alone suffers from low efficacy, poor stability, and high cost, hindering large-scale industrial application. Therefore, developing a non-oxidizing fungicide that combines high efficiency and broad-spectrum bactericidal activity with strong resistance to drug resistance, environmental friendliness, and suitability for industrial production has become an urgent technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a non-oxidizing bactericide for industrial circulating water and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention first proposes a non-oxidizing bactericide for industrial circulating water, which, by mass percentage, consists of the following components: 8.0%-12.0% degradable dicationic quaternary ammonium salt compound, 5.0%-8.0% double-chain quaternary ammonium salt, 3.0%-6.0% natural compound plant extract, 2.0%-4.0% cosolvent, 0.5%-1.0% chelating agent, and the balance being deionized water; The biodegradable dicationic quaternary ammonium salt compound has an effective content of ≥98%, an ester bond content of ≥25% in its molecular structure, and the general structural formula is: ; Where: R1=C 10 -C 14 Alkyl (preferably dodecyl); R2=C2-C4 short-chain alkyl (preferably glycol-based: -CH2CH2-); X - =Cl - ,Br - The molecule contains biodegradable ester bonds and dual cationic head groups, exhibiting extremely low critical micelle concentration, high surface activity, and strong cell membrane disruption capability.

[0007] The double-chain quaternary ammonium salt is decyl dimethyl ammonium chloride, with an active ingredient content of 78%-82%. Both double-chain quaternary ammonium salts and biodegradable dicationic quaternary ammonium salts are amphiphilic molecules. Upon reaching the critical micelle concentration (CMC) in water, the hydrophobic alkyl groups aggregate inward to form the micelle core, while the hydrophilic quaternary ammonium head groups extend outward. The biodegradable dicationic quaternary ammonium salt compound synthesized in this scheme exhibits an extremely low CMC, meaning it can form micelles at very low concentrations and possesses extremely high surface activity. This structure effectively reduces the surface tension of water, facilitating the spread and penetration of bactericides on pipe walls and biofilm surfaces. The two different quaternary ammonium salts tend to form mixed micelles in solution. Because both are cationic and structurally complementary, mixed micelles are generally more stable and have higher surface activity than single micelles.

[0008] The natural compound plant extract is a compound ethanol extract of mangosteen peel and henna seeds, with a feeding ratio of mangosteen peel to henna seeds of 3:2. The solid content of the extract is 30%, of which α-dextrin content is ≥1.5% and henna quinone content is ≥0.8%.

[0009] Preferably, the cosolvent is food-grade 1,2-propanediol or anhydrous ethanol, and the chelating agent is disodium ethylenediaminetetraacetate.

[0010] Disodium ethylenediaminetetraacetate (EDTA) acts as a metal ion chelating agent, forming stable water-soluble complexes with free calcium and magnesium ions in water. This prevents hard water ions from reacting with quaternary ammonium salts or phenolic hydroxyl groups in plant extracts to form precipitates. Simultaneously, EDTA can enhance cell membrane permeability and assist in sterilization by chelating metal ions on bacterial cell membranes (necessary for maintaining membrane structure).

[0011] Preferably, the preparation process of the degradable dicationic quaternary ammonium salt compound specifically includes the following steps: A dihalogenated ester compound and an N,N-dimethyl long-chain alkyl tertiary amine are added to a reaction vessel at a molar ratio of 1:2.0-2.2. Isopropanol or ethanol, weighing 30%-50% of the total material, are added and stirred until homogeneous. Under nitrogen protection, the mixture is heated to 60-80℃ and refluxed at atmospheric pressure for 6-10 hours. The solvent is removed by vacuum distillation to obtain a pale yellow, transparent, viscous liquid. The pH is adjusted to 5.0-7.0, and the mixture is filtered to obtain a degradable dicationic quaternary ammonium salt compound.

[0012] Dihaloesters undergo an SN2 nucleophilic substitution reaction with tertiary amines. The lone pair of electrons on the tertiary amine attacks the α-carbon of the haloalkane, forming a CN bond, while the halogen departs, forming a quaternary ammonium salt. The ester bond remains stable at 60-80℃ and under conditions without strong acids / bases, ensuring that the final molecule contains ≥25% degradable ester bonds. Since the molar ratio of the reactants, dihaloester and tertiary amine, is approximately 1:2, the final product is a symmetrical gemini structure with two positively charged centers.

[0013] Preferably, the dihalogenated ester compound is selected from one or more of ethylene glycol dichloroacetate, propylene glycol dichloroacetate, and butanediol dichloroacetate; the N,N-dimethyl long-chain alkyl tertiary amine is selected from one or more of N,N-dimethyldecyl tertiary amine, N,N-dimethyldodecyl tertiary amine, and N,N-dimethyltetradecyl tertiary amine.

[0014] The present invention also proposes a method for preparing the aforementioned non-oxidizing bactericide for industrial circulating water, comprising the following steps: S1. Preparation of natural compound plant extract: Mangosteen peel and henna seeds were dried, crushed and sieved separately, and then mixed at a mass ratio of 3:2 to obtain mixed raw materials; the mixed raw materials were extracted by cold soaking in 70% food-grade ethanol aqueous solution at room temperature, and the extract was filtered by pressure filtration, low-temperature vacuum concentration and ceramic membrane filtration to obtain a natural compound plant extract with a solid content of 30%. S2. Room temperature compound preparation: Add deionized water to the reaction vessel according to the ratio, and add chelating agent and cosolvent in sequence under room temperature stirring. Stir until completely dissolved to obtain the base liquid. Add double-chain quaternary ammonium salt and degradable dicationic quaternary ammonium salt compound in sequence to the base liquid. Stir until the system is homogeneous and transparent. Finally, add natural compound plant extract, stir continuously to homogenize, adjust the pH value of the system to 6.0-8.0, and filter to obtain the non-oxidizing bactericide.

[0015] Preferably, in step S1, the material-to-liquid ratio for cold maceration extraction at room temperature is 1:8, extraction is performed twice at room temperature, with each extraction lasting 24 hours and a stirring speed of 30 r / min; the temperature for low-temperature vacuum concentration is 40-45℃, the vacuum degree is -0.08 MPa, and the ethanol recovery rate is ≥95%.

[0016] Preferably, in step S2, all compounding processes are carried out at room temperature and pressure of 20-30℃, and the stirring speed is 60-80 r / min; after adding the double-chain quaternary ammonium salt, the mixture is stirred for 15 min; after adding the degradable double-cationic quaternary ammonium salt compound, the mixture is stirred for 20 min; and after adding the natural compound plant extract, the mixture is stirred for 30 min.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a self-developed biodegradable dicationic quaternary ammonium salt compound (Gemini type). Compared to traditional single-chain or double-chain quaternary ammonium salts, its molecular structure simultaneously contains dicationic head groups and ≥25% biodegradable ester bonds. The dicationic structure endows it with a higher positive charge density than conventional quaternary ammonium salts, enabling it to more efficiently adsorb onto the negatively charged bacterial cell membrane surface and disrupt membrane integrity. Simultaneously, the introduced ester bonds in the molecule endow it with biodegradable properties, solving the problems of traditional quaternary ammonium salts being difficult to degrade in the environment and having high residual toxicity, thus achieving a balance between highly efficient sterilization and environmental friendliness.

[0018] 2. This invention constructs a synergistic mechanism of strong adsorption-biomembrane penetration-multi-target killing through a ternary compound of degradable dicationic quaternary ammonium salt, double-chain quaternary ammonium salt, and natural complex plant extracts: Dicationic quaternary ammonium salts, with their extremely low critical micelle concentrations, significantly reduce the surface tension of the system, thus aiding in the spreading and penetration of the drug solution. Double-chain quaternary ammonium salts (disdecyldimethylammonium chloride) have strong hydrophobicity and can effectively penetrate microbial biofilms; The α-dextrin and senna quinone in the compound extract of mangosteen peel and henna seeds inhibit metabolic processes through multi-target action and complement quaternary ammonium salts.

[0019] While existing compound quaternary ammonium salt patents mention plant extracts, they are mostly based on single plant sources and do not specify the content of active ingredients. This invention ensures the stable exertion of synergistic effects by using a specific ratio (3:2) of compound and quantitative control of active ingredients (α-dextrin ≥1.5%, serotonin ≥0.8%).

[0020] 3. The plant extracts are derived from agricultural byproducts such as mangosteen peel and henna seeds, aligning with the concept of a circular economy. Food-grade 1,2-propanediol or anhydrous ethanol is used as the cosolvent, and disodium EDTA is used as the chelating agent, resulting in a low overall environmental impact. The plant extraction process employs room-temperature cold soaking and low-temperature vacuum concentration, avoiding damage to heat-sensitive active ingredients from high temperatures. Ethanol recovery is ≥95%, and the solvent is recyclable. The entire formulation of the bactericide is carried out at 20-30℃ under normal temperature and pressure, saving energy and reducing consumption. The ester bonds in the dicationic quaternary ammonium salt are degradable in the environment. The plant extracts are derived from nature, avoiding the residual risk of heavy metal bactericides and solving the industry pain points of high toxicity and difficult degradation of traditional industrial bactericides. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1: A non-oxidizing bactericide for industrial circulating water, comprising the following components by mass percentage: 8.0% biodegradable dicationic quaternary ammonium salt compound, 8.0% double-chain quaternary ammonium salt, 3.0% natural compound plant extract, 4.0% cosolvent, 0.5% chelating agent, with the balance being deionized water; The biodegradable dicationic quaternary ammonium salt compound has an active ingredient content of ≥98% and an ester bond content of ≥25% in its molecular structure. The double-chain quaternary ammonium salt is decyl dimethyl ammonium chloride, with an active ingredient content of 78%-82%. The natural compound plant extract is a compound ethanol extract of mangosteen peel and henna seeds, with a feeding ratio of mangosteen peel to henna seeds of 3:2. The solid content of the extract is 30%, of which α-dextrin content is ≥1.5% and henna quinone content is ≥0.8%.

[0023] The cosolvent is food-grade 1,2-propanediol or anhydrous ethanol, and the chelating agent is disodium ethylenediaminetetraacetate.

[0024] The preparation process of the degradable dicationic quaternary ammonium salt compound specifically includes the following steps: A dihalogenated ester compound and an N,N-dimethyl long-chain alkyl tertiary amine were added to a reaction vessel at a molar ratio of 1:2.2, along with 30% ethanol by mass of the total materials. The mixture was stirred until homogeneous. Under nitrogen protection, the temperature was raised to 70°C, and the reaction was carried out under reflux at atmospheric pressure for 8 hours. The solvent was removed by vacuum distillation to obtain a pale yellow, transparent, viscous liquid. The pH was adjusted to 6.0±0.5, and the mixture was filtered to obtain a degradable dicationic quaternary ammonium salt compound.

[0025] The dihalogenated esters are selected from one or more of ethylene glycol dichloroacetate, propylene glycol dichloroacetate, and butanediol dichloroacetate; the N,N-dimethyl long-chain alkyl tertiary amine is selected from one or more of N,N-dimethyldecyl tertiary amine, N,N-dimethyldodecyl tertiary amine, and N,N-dimethyltetradecyl tertiary amine.

[0026] The preparation method includes the following steps: S1. Preparation of natural compound plant extract: Mangosteen peel and henna seeds were dried, crushed and sieved separately, and then mixed at a mass ratio of 3:2 to obtain mixed raw materials; the mixed raw materials were extracted by cold soaking in 70% food-grade ethanol aqueous solution at room temperature, and the extract was filtered by pressure filtration, low-temperature vacuum concentration and ceramic membrane filtration to obtain a natural compound plant extract with a solid content of 30%. S2. Room temperature compound preparation: Deionized water is added to the reaction vessel according to the ratio. Chelating agent and cosolvent are added sequentially under room temperature stirring. Stirring is continued until completely dissolved to obtain the base liquid. Double-chain quaternary ammonium salt and degradable dicationic quaternary ammonium salt compound are added sequentially to the base liquid. Stirring is continued until the system is homogeneous and transparent. Finally, natural compound plant extract is added. Stirring is continued to homogenize the system. The pH value of the system is adjusted to 7.0±0.5. After filtration, the non-oxidizing bactericide is obtained.

[0027] In S1, the material-to-liquid ratio for room temperature cold soaking extraction is 1:8, and the extraction is performed twice at room temperature, with each extraction lasting 24 hours and a stirring speed of 30 r / min. The temperature for low-temperature vacuum concentration is 40-45℃, the vacuum degree is -0.08 MPa, and the ethanol recovery rate is ≥95%.

[0028] In S2, all compounding processes were carried out at room temperature and pressure of 25±2℃, with a stirring speed of 70r / min; after adding the double-chain quaternary ammonium salt, the mixture was stirred for 15min; after adding the biodegradable bis-cationic quaternary ammonium salt compound, the mixture was stirred for 20min; and after adding the natural compound plant extract, the mixture was stirred for 30min.

[0029] Example 2: A non-oxidizing bactericide for industrial circulating water, comprising the following components by mass percentage: 10.0% biodegradable dicationic quaternary ammonium salt compound, 6.5% double-chain quaternary ammonium salt, 4.5% natural compound plant extract, 3.0% cosolvent, 7.5% chelating agent, with the balance being deionized water; The biodegradable dicationic quaternary ammonium salt compound has an active ingredient content of ≥98% and an ester bond content of ≥25% in its molecular structure. The double-chain quaternary ammonium salt is decyl dimethyl ammonium chloride, with an active ingredient content of 78%-82%. The natural compound plant extract is a compound ethanol extract of mangosteen peel and henna seeds, with a feeding ratio of mangosteen peel to henna seeds of 3:2. The solid content of the extract is 30%, of which α-dextrin content is ≥1.5% and henna quinone content is ≥0.8%.

[0030] The cosolvent is food-grade 1,2-propanediol or anhydrous ethanol, and the chelating agent is disodium ethylenediaminetetraacetate.

[0031] The preparation process of the degradable dicationic quaternary ammonium salt compound specifically includes the following steps: A dihalogenated ester compound and an N,N-dimethyl long-chain alkyl tertiary amine were added to a reaction vessel at a molar ratio of 1:2.1, along with 40% ethanol by mass of the total materials. The mixture was stirred until homogeneous. Under nitrogen protection, the temperature was raised to 70°C, and the reaction was carried out under reflux at atmospheric pressure for 8 hours. The solvent was removed by vacuum distillation to obtain a pale yellow, transparent, viscous liquid. The pH was adjusted to 6.0±0.5, and the mixture was filtered to obtain a degradable dicationic quaternary ammonium salt compound.

[0032] The dihalogenated esters are selected from one or more of ethylene glycol dichloroacetate, propylene glycol dichloroacetate, and butanediol dichloroacetate; the N,N-dimethyl long-chain alkyl tertiary amine is selected from one or more of N,N-dimethyldecyl tertiary amine, N,N-dimethyldodecyl tertiary amine, and N,N-dimethyltetradecyl tertiary amine.

[0033] The preparation method includes the following steps: S1. Preparation of natural compound plant extract: Mangosteen peel and henna seeds were dried, crushed and sieved separately, and then mixed at a mass ratio of 3:2 to obtain mixed raw materials; the mixed raw materials were extracted by cold soaking in 70% food-grade ethanol aqueous solution at room temperature, and the extract was filtered by pressure filtration, low-temperature vacuum concentration and ceramic membrane filtration to obtain a natural compound plant extract with a solid content of 30%. S2. Room temperature compound preparation: Deionized water is added to the reaction vessel according to the ratio. Chelating agent and cosolvent are added sequentially under room temperature stirring. Stirring is continued until completely dissolved to obtain the base liquid. Double-chain quaternary ammonium salt and degradable dicationic quaternary ammonium salt compound are added sequentially to the base liquid. Stirring is continued until the system is homogeneous and transparent. Finally, natural compound plant extract is added. Stirring is continued to homogenize the system. The pH value of the system is adjusted to 7.0±0.5. After filtration, the non-oxidizing bactericide is obtained.

[0034] In S1, the material-to-liquid ratio for room temperature cold soaking extraction is 1:8, and the extraction is performed twice at room temperature, with each extraction lasting 24 hours and a stirring speed of 30 r / min. The temperature for low-temperature vacuum concentration is 40-45℃, the vacuum degree is -0.08 MPa, and the ethanol recovery rate is ≥95%.

[0035] In S2, all compounding processes were carried out at room temperature and pressure of 25±2℃, with a stirring speed of 70r / min; after adding the double-chain quaternary ammonium salt, the mixture was stirred for 15min; after adding the biodegradable bis-cationic quaternary ammonium salt compound, the mixture was stirred for 20min; and after adding the natural compound plant extract, the mixture was stirred for 30min.

[0036] Example 3: A non-oxidizing bactericide for industrial circulating water, comprising the following components by mass percentage: 12.0% biodegradable dicationic quaternary ammonium salt compound, 5.0% double-chain quaternary ammonium salt, 6.0% natural compound plant extract, 2.0% cosolvent, 1.0% chelating agent, with the balance being deionized water; The biodegradable dicationic quaternary ammonium salt compound has an active ingredient content of ≥98% and an ester bond content of ≥25% in its molecular structure. The double-chain quaternary ammonium salt is decyl dimethyl ammonium chloride, with an active ingredient content of 78%-82%. The natural compound plant extract is a compound ethanol extract of mangosteen peel and henna seeds, with a feeding ratio of mangosteen peel to henna seeds of 3:2. The solid content of the extract is 30%, of which α-dextrin content is ≥1.5% and henna quinone content is ≥0.8%.

[0037] The cosolvent is food-grade 1,2-propanediol or anhydrous ethanol, and the chelating agent is disodium ethylenediaminetetraacetate.

[0038] The preparation process of the degradable dicationic quaternary ammonium salt compound specifically includes the following steps: A dihalogenated ester compound and an N,N-dimethyl long-chain alkyl tertiary amine were added to a reaction vessel at a molar ratio of 1:2.0. Isopropanol, accounting for 50% of the total mass of the materials, was added and stirred until homogeneous. Under nitrogen protection, the mixture was heated to 70°C and refluxed at atmospheric pressure for 8 hours. The solvent was removed by vacuum distillation to obtain a pale yellow, transparent, viscous liquid. The pH was adjusted to 6.0±0.5, and the mixture was filtered to obtain a biodegradable dicationic quaternary ammonium salt compound.

[0039] The dihalogenated esters are selected from one or more of ethylene glycol dichloroacetate, propylene glycol dichloroacetate, and butanediol dichloroacetate; the N,N-dimethyl long-chain alkyl tertiary amine is selected from one or more of N,N-dimethyldecyl tertiary amine, N,N-dimethyldodecyl tertiary amine, and N,N-dimethyltetradecyl tertiary amine.

[0040] The preparation method includes the following steps: S1. Preparation of natural compound plant extract: Mangosteen peel and henna seeds were dried, crushed and sieved separately, and then mixed at a mass ratio of 3:2 to obtain mixed raw materials; the mixed raw materials were extracted by cold soaking in 70% food-grade ethanol aqueous solution at room temperature, and the extract was filtered by pressure filtration, low-temperature vacuum concentration and ceramic membrane filtration to obtain a natural compound plant extract with a solid content of 30%. S2. Room temperature compound preparation: Deionized water is added to the reaction vessel according to the ratio. Chelating agent and cosolvent are added sequentially under room temperature stirring. Stirring is continued until completely dissolved to obtain the base liquid. Double-chain quaternary ammonium salt and degradable dicationic quaternary ammonium salt compound are added sequentially to the base liquid. Stirring is continued until the system is homogeneous and transparent. Finally, natural compound plant extract is added. Stirring is continued to homogenize the system. The pH value of the system is adjusted to 7.0±0.5. After filtration, the non-oxidizing bactericide is obtained.

[0041] In S1, the material-to-liquid ratio for room temperature cold soaking extraction is 1:8, and the extraction is performed twice at room temperature, with each extraction lasting 24 hours and a stirring speed of 30 r / min. The temperature for low-temperature vacuum concentration is 40-45℃, the vacuum degree is -0.08 MPa, and the ethanol recovery rate is ≥95%.

[0042] In S2, all compounding processes were carried out at room temperature and pressure of 25±2℃, with a stirring speed of 70r / min; after adding the double-chain quaternary ammonium salt, the mixture was stirred for 15min; after adding the biodegradable bis-cationic quaternary ammonium salt compound, the mixture was stirred for 20min; and after adding the natural compound plant extract, the mixture was stirred for 30min.

[0043] The following comparison model was also set: Comparative Example 1: Based on Example 2, the difference is that no natural compound plant extracts are added, and their mass percentage is made up by deionized water, while the rest is the same as in Example 2.

[0044] Comparative Example 2: Based on Example 2, the difference is that the compound extract of mangosteen peel and henna seed in this invention is replaced with a single mangosteen peel extract, the mass percentage is the same, and the rest is the same as in Example 2.

[0045] Comparative Example 3: Based on Example 2, the difference is that the biodegradable dicationic quaternary ammonium salt compound in this invention is replaced with an equal amount of conventional single-chain dodecyl dimethyl benzyl ammonium chloride, and the rest is the same as in Example 2.

[0046] Comparative Example 4: Based on Example 2, the difference is that the biodegradable dicationic quaternary ammonium salt compound in this invention is replaced with an equal amount of non-degradable Gemini quaternary ammonium salt without ester bonds, and the rest is the same as in Example 2.

[0047] Performance testing: The samples from Examples 1-3 and Comparative Examples 1-4 were subjected to performance testing. The testing methods were in accordance with GB / T 14643 "Determination of Bacteria and Algae in Industrial Circulating Cooling Water" and GB / T 20778-2006 "Evaluation Method for Biodegradable Performance of Water Treatment Agents". The test results are shown in the table below: Table 1. Test results of various parameters after industrial circulating water sterilization treatment Data Analysis: Examples 1-3 all showed a bactericidal rate of ≥99.6% against heterotrophic bacteria and ≥99.2% against sulfate-reducing bacteria (SRB). Example 2 showed the best performance, with bactericidal rates of 99.9% and 99.8%, respectively, proving that the formulation of the present invention has a stable and efficient bactericidal effect within the preferred ratio range. Comparative Example 1 (without plant extract) showed a bactericidal rate of 96.5% and 92.3%, indicating that plant extracts have a significant contribution to improving the bactericidal effect. Comparative Example 2 (single mangosteen peel extract) showed a bactericidal rate of 98.2% and 96.8%, which was better than Comparative Example 1 but lower than the examples, verifying that the synergistic effect of mangosteen peel and henna seed combination is better than that of a single source. Comparative Example 3 (conventional single-chain quaternary ammonium salt) showed the lowest bactericidal rate (95.8% and 91.5%), proving the advantage of the dual-cationic structure in bactericidal efficiency. Comparative Example 4 (non-degradable Gemini) showed a higher bactericidal rate (98.5%, 97.2%), but slightly lower than the Example, indicating that the introduction of degradable ester bonds resulted in minimal sacrifice in maintaining bactericidal activity.

[0048] Example 2 showed MICs of 6, 9, and 12 mg / L against Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Pseudomonas aeruginosa (drug-resistant G. aeruginosa), respectively, all the lowest among the groups, demonstrating the broad-spectrum and highly effective antibacterial properties of this invention. Comparative Example 1 showed a significantly higher MIC (18-32 mg / L), proving that the multi-target action of the plant extract is crucial for reducing the MIC. Comparative Example 2's MIC (12-24 mg / L) was between that of Example 1 and Comparative Example 1, further validating that the compound extract is superior to the single extract. Comparative Example 3 showed the highest MIC (22-38 mg / L), demonstrating the limited antibacterial activity of conventional single-chain quaternary ammonium salts. Comparative Example 4 had a lower MIC (10-20 mg / L), but combined with degradation data, it reflected a trade-off between high efficiency and environmental friendliness.

[0049] The 28-day biodegradation rates of Examples 1-3 were all above 78%, with Example 2 reaching 81.2%, falling into the "easily biodegradable" category (>60%), demonstrating the effectiveness of the ester bond design in the molecular structure. Comparative Example 1 had a degradation rate of 85.6%, slightly higher than the Examples, because it did not contain plant extracts (a small amount of recalcitrant components slightly affected the degradation rate). However, considering the bactericidal rate data, the Examples achieved good degradability while maintaining high bactericidal efficiency, exhibiting the best overall performance. Comparative Example 2 had a degradation rate of 82.3%, comparable to the Examples. Comparative Example 3 had a degradation rate of only 52.4% (moderately degradable), demonstrating the poor degradability of conventional quaternary ammonium salts. Comparative Example 4 had a degradation rate of only 32.1% (recalcitrant), demonstrating that Gemini quaternary ammonium salts without ester bonds pose an environmental residue risk.

[0050] Examples 1-3 showed an activity retention rate of ≥97% after storage at 54℃ for 14 days, with Example 2 reaching 98.5%, demonstrating that the formulation of the present invention has good thermal stability and is suitable for industrial storage and transportation. Comparative Examples 1-4 showed retention rates between 96.5% and 99.1%, with little difference, indicating that the formulations had comparable ability to maintain bactericidal activity, and the stability was mainly ensured by the compounding process and co-solvents.

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A non-oxidizing bactericide for industrial circulating water, characterized in that, By mass percentage, it consists of the following components: 8.0%-12.0% biodegradable dicationic quaternary ammonium salt compound, 5.0%-8.0% double-chain quaternary ammonium salt, 3.0%-6.0% natural compound plant extract, 2.0%-4.0% cosolvent, 0.5%-1.0% chelating agent, and the balance being deionized water; The biodegradable dicationic quaternary ammonium salt compound has an active ingredient content of ≥98% and an ester bond content of ≥25% in its molecular structure. The double-chain quaternary ammonium salt is decyl dimethyl ammonium chloride, with an active ingredient content of 78%-82%. The natural compound plant extract is a compound ethanol extract of mangosteen peel and henna seeds, with a feeding ratio of mangosteen peel to henna seeds of 3:

2. The solid content of the extract is 30%, of which α-dextrin content is ≥1.5% and henna quinone content is ≥0.8%.

2. The non-oxidizing bactericide for industrial circulating water according to claim 1, characterized in that, The cosolvent is food-grade 1,2-propanediol or anhydrous ethanol, and the chelating agent is disodium ethylenediaminetetraacetate.

3. The non-oxidizing bactericide for industrial circulating water according to claim 1, characterized in that, The preparation process of the degradable dicationic quaternary ammonium salt compound specifically includes the following steps: A dihalogenated ester compound and an N,N-dimethyl long-chain alkyl tertiary amine are added to a reaction vessel at a molar ratio of 1:2.0-2.

2. Isopropanol or ethanol, weighing 30%-50% of the total material, are added and stirred until homogeneous. Under nitrogen protection, the mixture is heated to 60-80℃ and refluxed at atmospheric pressure for 6-10 hours. The solvent is removed by vacuum distillation to obtain a pale yellow, transparent, viscous liquid. The pH is adjusted to 5.0-7.0, and the mixture is filtered to obtain a degradable dicationic quaternary ammonium salt compound.

4. The non-oxidizing bactericide for industrial circulating water according to claim 3, characterized in that, The dihalogenated esters are selected from one or more of ethylene glycol dichloroacetate, propylene glycol dichloroacetate, and butanediol dichloroacetate; the N,N-dimethyl long-chain alkyl tertiary amine is selected from one or more of N,N-dimethyldecyl tertiary amine, N,N-dimethyldodecyl tertiary amine, and N,N-dimethyltetradecyl tertiary amine.

5. A method for preparing a non-oxidizing bactericide for industrial circulating water according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of natural compound plant extract: Mangosteen peel and henna seeds were dried, crushed and sieved separately, and then mixed at a mass ratio of 3:2 to obtain mixed raw materials; the mixed raw materials were extracted by cold soaking in 70% food-grade ethanol aqueous solution at room temperature, and the extract was filtered by pressure filtration, low-temperature vacuum concentration and ceramic membrane filtration to obtain a natural compound plant extract with a solid content of 30%. S2. Room temperature compound preparation: Add deionized water to the reaction vessel according to the ratio, and add chelating agent and cosolvent in sequence under room temperature stirring. Stir until completely dissolved to obtain the base liquid. Add double-chain quaternary ammonium salt and degradable dicationic quaternary ammonium salt compound in sequence to the base liquid. Stir until the system is homogeneous and transparent. Finally, add natural compound plant extract, stir continuously to homogenize, adjust the pH value of the system to 6.0-8.0, and filter to obtain the non-oxidizing bactericide.

6. The method for preparing the non-oxidizing bactericide for industrial circulating water according to claim 5, characterized in that, In S1, the material-to-liquid ratio for room temperature cold soaking extraction is 1:8, and the extraction is performed twice at room temperature, with each extraction lasting 24 hours and a stirring speed of 30 r / min. The temperature for low-temperature vacuum concentration is 40-45℃, the vacuum degree is -0.08 MPa, and the ethanol recovery rate is ≥95%.

7. The method for preparing the non-oxidizing bactericide for industrial circulating water according to claim 5, characterized in that, In step S2, all compounding processes are carried out at room temperature and pressure of 20-30℃, with a stirring speed of 60-80 r / min; after adding the double-chain quaternary ammonium salt, the mixture is stirred for 15 min; after adding the biodegradable bis-cationic quaternary ammonium salt compound, the mixture is stirred for 20 min; and after adding the natural compound plant extract, the mixture is stirred for 30 min.

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