Sodium acetate solution as well as preparation method and application thereof

Abstract

The invention discloses a sodium acetate solution and a preparation method and application thereof, and relates to the technical field of carbon source agents.According to the preparation method, sodium carbonate is adopted to replace traditional sodium hydroxide to serve as an alkali source, sodium acetate is prepared through a mild neutralization reaction, and use of highly corrosive raw materials and generation of volatile organic compounds are avoided; and a multifunctional modified stabilizer system is introduced. The system is composed of calcium-based montmorillonite, a quaternary ammonium salt surfactant, a sodium modifying agent and a chitosan derivative, and the stability of a sodium acetate solution is remarkably improved through an intercalation modification process. The addition of the modified stabilizer not only enhances the anti-settling and anti-layering capabilities of the sodium acetate solution, but also endows the product with excellent heavy metal adsorption performance and antibacterial effect, and effectively solves the problems that a traditional sodium acetate solution is easy to breed microorganisms and poor in stability when stored in a high-temperature and high-humidity environment. The preparation method can be widely applied to the fields of sewage treatment, aquaculture and the like.

Description

Technical Field

[0001] This application relates to the technical field of carbon source reagents, and in particular to a sodium acetate solution, its preparation method, and its application. Background Technology

[0002] Currently, in the field of wastewater treatment, the supply of carbon sources is the core link in achieving biological denitrification and degradation of organic matter. Sodium acetate, due to its advantages such as high carbon source purity, high microbial utilization rate, and fast reaction speed, is widely used in the denitrification treatment process of municipal sewage and industrial wastewater. Traditionally, sodium acetate solution is prepared using sodium hydroxide as the alkali source, generated through the neutralization reaction of acetic acid and sodium hydroxide. However, this process has several problems: Firstly, sodium hydroxide is a highly corrosive raw material, requiring specialized equipment for transportation and storage. Furthermore, the reaction process is prone to localized overheating, leading to a sudden rise in system temperature, which not only increases energy consumption but may also exacerbate acetic acid volatilization, generating large amounts of waste gas and causing secondary environmental pollution. Secondly, sodium hydroxide is a high-cost raw material, and the sodium acetate solution produced by the neutralization reaction has poor stability, easily leading to microbial growth and solution stratification during long-term storage. Especially in high-temperature and high-humidity environments, additional preservatives are required, further increasing production and treatment costs. To address the aforementioned issues, the preparation process of sodium acetate using sodium carbonate as the alkali source has gradually become a research hotspot. Sodium carbonate is not only low in corrosiveness and high in safety, but also reacts with acetic acid in a mild manner, effectively controlling the volatilization of VOCs.

[0003] Currently, with the increasing industrial agglomeration in industrial parks, the complexity of water quality faced by integrated wastewater treatment plants is growing, especially in parks with concentrated chemical, electronics, and food processing industries, which places higher demands on the performance of sodium acetate as a carbon source. When multiple parks are concentrated in one area, for example, due to the mixing of food processing wastewater, the number of bacteria in the wastewater is high, and the total number of bacteria in the water is even higher during the high temperatures of summer. This wastewater treatment plant needs to add sodium acetate as a carbon source to improve denitrification efficiency, but traditional sodium acetate solutions have some shortcomings in practical applications. After being stored in an environment above 35°C for more than 72 hours in summer, the solution becomes turbid and develops an odor, and microbial growth leads to a decrease in carbon source utilization, requiring frequent tank cleaning and affecting the continuity of treatment. At the same time, Cu²⁺ and Ni²⁺ in the wastewater tend to accumulate in the biofilm, inhibiting microbial activity, shortening the membrane cleaning cycle to 15 days / time, and increasing operation and maintenance costs. In addition, high concentrations of bacteria in the wastewater not only consume some carbon source, but may also cause biofouling of the membrane module, further reducing treatment efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a sodium acetate solution with good stability, excellent heavy metal adsorption performance and antibacterial effect, which can be applied in multiple fields such as wastewater treatment.

[0005] Firstly, the sodium acetate solution, its preparation method, and its application provided in this application adopt the following technical solution: A sodium acetate solution comprises the following raw materials: sodium carbonate, water, acetic acid, antibacterial agent, and modified stabilizer; the modified stabilizer comprises calcium-based montmorillonite, quaternary ammonium salt surfactant, sodium-modifying agent, and chitosan derivative; the mass ratio of calcium-based montmorillonite, quaternary ammonium salt surfactant, sodium-modifying agent, and chitosan derivative is 110:(5-10):(15-40):(75-130); the quaternary ammonium salt surfactant comprises a sodium phosphate salt, an epoxy-containing monomer I, and a tertiary amine-containing monomer II.

[0006] By employing the above technical solution, sodium acetate is produced by reacting sodium carbonate and acetic acid. The reaction is mild, and the byproducts are CO2 and water, which are easily separated and purified. The resulting solution has high purity and few impurities. Simultaneously, the addition of antibacterial agents inhibits microbial growth and extends the shelf life of the solution. Adding modified stabilizers significantly improves the stability and functionality of the sodium acetate solution. Through the action of a sodium-modifying agent, Na⁺ replaces Ca²⁺ in the interlayer of calcium-based montmorillonite, forming an intermediate that increases the interlayer spacing and enhances adsorption capacity. In quaternary ammonium salt surfactants, the phosphate functional groups provided by sodium phosphate salts and the epoxy groups of epoxy monomer one react with the tertiary amine groups of tertiary amine monomer two, allowing them to intercalate into the interlayer of montmorillonite, further expanding the interlayer spacing and enhancing its compatibility with chitosan derivatives. Chitosan derivatives, containing amino and hydroxyl functional groups, can bind to the surface of montmorillonite and the active groups of quaternary ammonium salts through hydrogen bonds and electrostatic attraction, constructing a stable network structure. This not only improves the anti-settling and anti-stratification ability of sodium acetate solution but also endows it with additional functions such as thickening and film formation. In the preparation of the modified stabilizer, the components are combined in a mass ratio of 110:(5-10):(15-40):(75-130) to maximize the synergistic effect within the modified stabilizer, ultimately improving the stability, functionality, and storage properties of the sodium acetate solution.

[0007] Optionally, the mass ratio of the sodium phosphate salt, the epoxy group-containing monomer one, and the tertiary amine-containing monomer two is 1:(2-4):(2-5).

[0008] By employing the above technical solution, the phosphate functional group provided by the sodium phosphate salt serves as the reaction initiation site. It first undergoes a ring-opening reaction with the epoxy group in monomer one containing an epoxy group. The ring structure of the epoxy group breaks under the nucleophilic attack of the phosphate group, forming an intermediate containing a hydroxyl group and a phosphate ester bond. Controlling the amount of monomer one at this point ensures that each sodium phosphate salt molecule is grafted with a sufficient amount of epoxy ring-opening unit, reserving ample active sites for the subsequent quaternization reaction. The tertiary amine group in monomer two, which is subsequently added, undergoes a quaternization reaction with the residual epoxy group or other active groups in the intermediate. The nitrogen atom of the tertiary amine group acts as a nucleophilic center, combining with the active carbon atom after the epoxy group ring-opening to form a quaternary ammonium salt structure. At this ratio, the amount of tertiary amine-containing monomer retains the hydrophilicity and coordination ability of the phosphate ester group while introducing hydrophobicity and cationic activity through the quaternary ammonium salt group. Ultimately, this ratio allows the quaternary ammonium salt surfactant to simultaneously possess good surface activity, dispersibility, and stability, making it suitable for subsequent intercalation synergy with montmorillonite.

[0009] Optionally, the chitosan derivative is any one of chitosan oligosaccharide, hydroxypropyl chitosan, or xanthate-modified chitosan.

[0010] By adopting the above technical solutions, the carboxyl groups introduced by chitosan oligosaccharides can enhance the electrostatic binding force with cations on the montmorillonite surface. Simultaneously, the hydrophilicity of the carboxyl groups can improve its dispersibility in sodium acetate solution, facilitating the construction of a stable network. The hydroxypropyl groups in hydroxypropyl chitosan are flexible groups, which can weaken the rigidity of the chitosan molecular chain, enhance its compatibility with quaternary ammonium salt surfactants, reduce aggregation, and improve the uniformity of the stabilizer. The xanthic acid groups in xanthated chitosan possess both coordination and hydrophilicity, forming coordination bonds with interlayer metal ions in montmorillonite to strengthen the binding, and further enhancing the anti-settling ability of the solution system through strong hydrophilicity. It also has heavy metal adsorption properties. Comparing the three, chitosan oligosaccharides exhibit stronger electrostatic interactions, hydroxypropyl chitosan has better compatibility, and xanthated chitosan demonstrates more prominent coordination and hydrophilic synergy. All three can enhance the stability and functionality of the system through the interaction of their functional groups with montmorillonite and quaternary ammonium salts.

[0011] Optionally, the method for preparing xanthate-modified chitosan includes the following steps: Chitosan and carbon disulfide are heated and stirred under alkaline conditions to precipitate. The precipitate is washed and dried to obtain xanthan acidified chitosan.

[0012] By adopting the above technical solution, chitosan and carbon disulfide are heated and stirred under alkaline conditions. The alkaline environment allows the amino and hydroxyl groups in the chitosan molecules to form negatively charged active sites, which undergo nucleophilic addition reactions with carbon disulfide, efficiently introducing xanthic acid groups, which can stably bind to the chitosan molecular chain. Subsequent precipitation, washing and drying steps can accurately remove unreacted carbon disulfide, alkaline byproducts and other impurities, avoiding residual substances from affecting the structural stability of the product. The resulting xanthic acid-modified chitosan not only retains the original biocompatibility of chitosan, but also significantly improves its chelating, hygroscopic and bioadhesive properties due to the introduction of xanthic acid groups, making it suitable for the adsorption of heavy metals in wastewater.

[0013] Optionally, the tertiary amine-containing monomer II is either lauramidopropyl dimethyl tertiary amine or dodecyl dimethyl tertiary amine.

[0014] By employing the above-mentioned technical solutions, both lauramide propyl dimethyl tertiary amine and dodecyl dimethyl tertiary amine contain tertiary amine functional groups, endowing the monomers with excellent basicity and nucleophilic reactivity. The amide bond introduced in the former enhances molecular polarity and biocompatibility, while the dodecyl hydrophobic chain in the latter emphasizes hydrophobicity. Both can be functionally modified through quaternization of the tertiary amine groups. By selecting these two tertiary amine monomers, the controllability of the reaction can be ensured by relying on the tertiary amine functional groups, and their structural differences can be adapted to different application scenarios.

[0015] Optionally, the sodium-sodium agent is either sodium silicate or sodium pyrophosphate.

[0016] By adopting the above technical solutions, sodium silicate and sodium pyrophosphate, as sodizing agents, share a core advantage: sodium ions can sodize and modify calcium-based montmorillonite. Sodium silicate contains silicate ions, whose anions readily form colloidal systems, enhancing the dispersibility and stability of the modified material. Sodium pyrophosphate contains pyrophosphate ions, exhibiting a stronger ability to chelate metal ions and reducing interference from metal impurities during the sodizing process.

[0017] Optionally, the preparation method of the modified stabilizer includes the following steps: S1. Disperse calcium-based montmorillonite in a solvent, add quaternary ammonium salt surfactant and sodium-forming agent, heat and stir, filter, wash, dry, and grind to obtain an intermediate; S2. Disperse the intermediate in a solvent, add an acid solution, add the chitosan derivative, stir, centrifuge to obtain a solid, wash the solid, and dry to obtain the modified stabilizer.

[0018] By adopting the above technical solution, in step S1, the sodium ions of the sodium-modifying agent further enhance the interlayer cation exchange, and the quaternary ammonium groups of the quaternary ammonium salt can undergo ion exchange with the calcium ions in the interlayer of calcium-based montmorillonite, realizing the transformation of calcium groups into intermediates, widening the interlayer spacing and improving interfacial activity. In step S2, the acid solution protonates the amino groups of the chitosan derivative, causing them to bind to the interlayer of the intermediate through electrostatic interactions and anchor them in the interlayer of montmorillonite; the finally obtained modified stabilizer has both layered structural stability and interfacial adhesion.

[0019] Optionally, the preparation method of the quaternary ammonium salt surfactant includes the following steps: Add the sodium phosphate salt to an acidic solvent, adjust the pH to 2-4, add monomer one containing an epoxy group, heat and stir, add monomer two containing a tertiary amine, adjust the pH to 8-10, heat and stir to obtain a quaternary ammonium salt surfactant.

[0020] By employing the above technical solution, the phosphorus-containing sodium salt is activated under acidic conditions, undergoing a ring-opening reaction with the epoxy group of epoxy monomer one to introduce a phosphorus-containing group. Subsequently, the pH is adjusted to be alkaline, which facilitates the reaction of the tertiary amine group of monomer two (containing a tertiary amine) with the active sites in the system, completing the quaternization. The resulting quaternary ammonium salt surfactant possesses both phosphorus and quaternary ammonium group characteristics, exhibiting superior surface activity and dispersing properties.

[0021] Secondly, the sodium acetate solution, its preparation method, and its application provided in this application adopt the following technical solution: A method for preparing a sodium acetate solution includes the following steps: Heat water, add sodium carbonate and acetic acid while stirring, stir until the pH does not change, add water, stir, add modifier stabilizer and antibacterial agent, stir, and adjust the pH to 7.5-9 to obtain sodium acetate solution.

[0022] By employing the above technical solution, sodium carbonate reacts with acetic acid under heating and stirring. Hydrogen ions and carbonate ions gradually combine to generate carbon dioxide and water. Stirring until the pH remains unchanged ensures a complete reaction and avoids raw material residue. After adjusting the concentration with water, stabilizers and antibacterial agents are added to inhibit the possible aggregation of impurity ions or component decomposition in the solution. Finally, adjusting the pH to a weakly alkaline environment maintains the dissociation equilibrium of sodium acetate, preventing its hydrolysis and deterioration, while also providing excellent antibacterial effects.

[0023] Thirdly, the sodium acetate solution, its preparation method, and its application provided in this application adopt the following technical solution: An application of a sodium acetate solution in wastewater treatment and aquaculture water conditioning.

[0024] In this formula, some of the ingredients and their functions are as follows: Sodium carbonate: Sodium carbonate is the core raw material for sodium acetate. The carbonate ions it contains can undergo an acid-base reaction with the carboxyl groups of acetic acid. The carbonate ions gradually combine with the hydrogen ions released from acetic acid to produce carbon dioxide, water, and sodium acetate. This reaction is mild and the byproducts are easily separated, ensuring efficient production of sodium acetate while avoiding the introduction of additional impurities.

[0025] Water: Water mainly acts as a solvent in the preparation of sodium acetate solution, dissolving sodium carbonate, acetic acid, and the generated sodium acetate, ensuring sufficient contact between the reactants. Simultaneously, water promotes ion dissociation during heating and stirring, facilitating the reaction between carbonate and acetate carboxyl groups.

[0026] Acetic acid: Acetic acid is one of the core raw materials for the preparation of sodium acetate. Its carboxyl functional group can react with the carbonate ion of sodium carbonate to produce carbon dioxide, water and sodium acetate.

[0027] Antibacterial agents: The main function of antibacterial agents is to inhibit the growth of microorganisms in sodium acetate solution, thereby extending shelf life. Simultaneously, antibacterial agents can synergistically enhance antibacterial effects with chitosan derivatives. The amino and other functional groups of chitosan derivatives can adsorb microorganisms, increasing the contact efficiency between the antibacterial agent and microorganisms. Through synergy, the two further enhance the antibacterial effect.

[0028] Calcium-based montmorillonite: Calcium-based montmorillonite is a core raw material for preparing modified stabilizers. Its interlayer contains exchangeable calcium ions, and its surface forms a negatively charged layered structure. During modification, its interlayer calcium ions exchange with the sodium ions of the sodilator and can also replace the quaternary ammonium groups of the quaternary ammonium salt surfactant, significantly widening the interlayer spacing after conversion into an intermediate. This enhances the anti-sedimentation and anti-stratification ability of sodium acetate solution, while also adsorbing impurities.

[0029] Sodium-modifying agent: Sodium silicate is used as the sodium-modifying agent in this application. Its core function is to achieve sodium modification of calcium-based montmorillonite. The sodium ions it contains can undergo ion exchange with calcium ions between the calcium-based montmorillonite layers, displacing calcium ions and transforming the calcium-based montmorillonite into an intermediate, significantly widening the interlayer spacing and improving adsorption and interfacial activity. This process produces no harmful byproducts, optimizing the structural properties of montmorillonite and laying the foundation for subsequent quaternary ammonium salt intercalation and chitosan derivative bonding.

[0030] Chitosan derivatives: Chitosan derivatives are key functional components of modified stabilizers, and their amino and hydroxyl functional groups can play multiple roles. In acidic solutions, the protonated amino groups can electrostatically bind to the negatively charged groups on the surface of intermediates. Hydroxyl groups or other carrier groups can also form hydrogen bonds with quaternary ammonium salt surfactants. These effects anchor the chitosan derivatives within the montmorillonite layers, constructing a stable network that enhances the anti-sedimentation and anti-stratification capabilities of sodium acetate solutions. Furthermore, due to their hydrophilicity or coordination properties, they impart functions such as heavy metal adsorption to the solution, ensuring stability and functionality throughout the entire preparation process.

[0031] Sodium hexametaphosphate: In this application, the sodium hexametaphosphate is used as the sodium hexametaphosphate. Sodium hexametaphosphate, as a sodium hexametaphosphate salt, is a key starting material for the preparation of quaternary ammonium salt surfactants. Its phosphate functional groups are activated under acidic conditions, initiating a nucleophilic attack on the epoxy group of the epoxy monomer, causing the epoxy ring structure to break and forming an intermediate containing a hydroxyl group and a phosphate ester bond, reserving active sites for subsequent quaternization. Simultaneously, the coordinating ability of the phosphate group endows the final quaternary ammonium salt surfactant with good dispersibility, allowing it to smoothly intercalate between montmorillonite layers and enhancing its compatibility with chitosan derivatives.

[0032] Monomer 1 containing epoxy groups: Under acidic conditions, the epoxy group is nucleophilically attacked by the phosphate group of sodium hexametaphosphate, causing the ring structure to break and forming an intermediate containing a hydroxyl group and a phosphate ester bond, reserving an active site for subsequent reactions; subsequently, the residual active group of the intermediate reacts with the tertiary amine group of monomer 2 containing tertiary amine. Through the ring-opening and linking effects of the epoxy groups, the phosphorus group and the quaternary ammonium group are combined into the same molecule, endowing the quaternary ammonium salt surfactant with hydrophobic and cationic activity.

[0033] Monomer II containing tertiary amine: Under alkaline conditions, the nitrogen atom of the tertiary amine group acts as a nucleophilic center, undergoing a quaternization reaction with the intermediate formed after ring opening of the epoxy-containing monomer I, generating a quaternary ammonium salt structure. Simultaneously, its own amide bond or long alkyl chain endows the product with polarity, biocompatibility, and hydrophobicity, making the quaternary ammonium salt surfactant also possess cationic activity, enabling efficient intercalation of montmorillonite.

[0034] In summary, this application includes at least one of the following beneficial technical effects: 1. Compared with existing technologies, this method involves the reaction of a sodium phosphate salt, an epoxy-containing monomer, and a tertiary amine-containing monomer. Under acidic conditions, the phosphate is activated and undergoes nucleophilic attack on the epoxy group for ring opening. Then, under alkaline conditions, the tertiary amine group completes quaternization, forming a surfactant with both a phosphate group and a quaternary ammonium salt structure. The phosphate group endows the product with excellent dispersibility and coordination ability, while the quaternary ammonium group provides cationic activity and hydrophobicity, enabling the surfactant to efficiently intercalate into the montmorillonite interlayer, enhancing its compatibility with chitosan derivatives, and laying the foundation for constructing a stable functional system. 2. Compared with existing technologies, the modified stabilizer uses calcium-based montmorillonite as its core, which is converted into an intermediate by a sodium-based agent, significantly expanding the interlayer spacing. Quaternary ammonium salt surfactants enter the interlayer through ion exchange intercalation, further enhancing interfacial activity. Chitosan derivatives are anchored in the interlayer through electrostatic attraction and hydrogen bonding, constructing a stable network structure. When this modified stabilizer is added to sodium acetate solution, it significantly improves the system's anti-settling and anti-stratification capabilities, while also endowing it with antibacterial activity and heavy metal adsorption functions, comprehensively enhancing the storage stability of sodium acetate solution in complex environments. Detailed Implementation

[0035] Unless otherwise specified, the parameters and sources of the specific chemical substances used in the embodiments and comparative examples of this application are all commercially available products. Chitosan, product number: S11064-500g, degree of deacetylation 90%, viscosity ≤500cps, Shanghai Yuanye Biotechnology Co., Ltd. Glycidyl methacrylate, product number: S60373-500g, Shanghai Yuanye Biotechnology Co., Ltd. Chitosan oligosaccharide, product number: S31060-500g, MW<3000, brand: Yuanye; Calcium-based montmorillonite, CAS No.: 1302-78-9, Guangzhou Yifeng Chemical Technology Co., Ltd.; Antibacterial agent, 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one, product number: CMIT / MIT-14, Weifang Yukai Chemical Co., Ltd. Example 1

[0036] A method for preparing a sodium acetate solution includes the following steps: The first step is to prepare the modified stabilizer.

[0037] A 0.1 t sodium hexametaphosphate solution was provided, and the pH was adjusted to 4 with a 10 wt% nitric acid solution. 0.3 t glycidyl methacrylate was added, and the mixture was heated to 70°C and stirred at 500 rpm for 2 hours to obtain the first mixture. Maintaining a constant temperature of 70°C, 0.2 t lauramidopropyl dimethyl tertiary amine was mixed with the first mixture, and the pH was adjusted to 8 with a 5 wt% sodium hydroxide aqueous solution. The mixture was heated to 90°C and stirred at 500 rpm for 3 hours. The mixture was then dried at 60°C under a vacuum of -0.08 MPa for 10 hours to obtain the quaternary ammonium salt surfactant.

[0038] 0.11 t of calcium-based montmorillonite was dispersed in 0.8 t of water to obtain a calcium-based montmorillonite dispersion. 0.008 t of quaternary ammonium salt surfactant and 0.03 t of sodium silicate were mixed with the calcium-based montmorillonite dispersion, heated to 65 °C, and stirred at 500 rpm for 30 h to obtain a second mixture. The second mixture was filtered to obtain a solid, which was washed three times with water. The solid from the last wash was dried at 60 °C for 10 h and activated at 110 °C for 0.5 h to obtain an activated solid. The activated solid was ground to obtain an intermediate.

[0039] The obtained intermediate was dispersed in 1 t of water to obtain a calcium-based montmorillonite dispersion. The pH of the calcium-based montmorillonite dispersion was adjusted to 3 with 10 wt% nitric acid solution to obtain an acidic calcium-based montmorillonite dispersion. The acidic calcium-based montmorillonite dispersion was mixed with 0.095 t of chitosan oligosaccharide, heated to 70 °C, and stirred at 500 rpm for 5 h to obtain a third mixture. The third mixture was centrifuged at 800 rpm for 20 min to obtain a centrifuged solid. The centrifuged solid was washed three times with water, dried at 60 °C and a vacuum of -0.08 MPa for 8 h, and ground to obtain a modified stabilizer.

[0040] The second step is to prepare a sodium acetate solution.

[0041] 10 tons of water were provided and the water temperature was controlled at 10°C. 4 tons of sodium carbonate were added, and the mixture was stirred at 500 rpm for 1 hour to obtain a sodium carbonate solution. The sodium carbonate solution was then added to 7.18 tons of 70 wt% acetic acid solution, and stirred at 500 rpm for 1 hour. Acetic acid was added to adjust the pH to 9, yielding a fourth mixture. This fourth mixture was then added to 9.85 tons of water, and stirred at 500 rpm for 1 hour. 0.2 tons of a modifier and 0.1 tons of 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one were added, and the mixture was stirred at 500 rpm for 1 hour. 70 wt% acetic acid solution was added to adjust the pH to 8, yielding a sodium acetate solution. Example 2

[0042] The difference between Example 2 and Example 1 is that the 0.2t lauramidopropyl dimethyl tertiary amine in Example 1 is replaced with 0.3t lauramidopropyl dimethyl tertiary amine. Example 3

[0043] The difference between Example 3 and Example 1 is that the 0.2t lauramidopropyl dimethyl tertiary amine in Example 1 is replaced with 0.4t lauramidopropyl dimethyl tertiary amine. Example 4

[0044] The difference between Example 4 and Example 2 is that 0.008t of quaternary ammonium salt surfactant is replaced with 0.005t of quaternary ammonium salt surfactant. Example 5

[0045] The difference between Example 5 and Example 2 is that 0.008t of quaternary ammonium salt surfactant is replaced with 0.007t of quaternary ammonium salt surfactant. Example 6

[0046] The difference between Example 6 and Example 2 is that 0.008t of quaternary ammonium salt surfactant is replaced with 0.01t of quaternary ammonium salt surfactant. Example 7

[0047] The difference between Example 7 and Example 2 is that 0.095t of chitosan oligosaccharide is replaced with 0.095t of hydroxypropyl chitosan. Example 8

[0048] The difference between Example 8 and Example 2 is that 0.095t of chitosan oligosaccharide is replaced with 0.095t of xanthan acidified chitosan.

[0049] The preparation method of xanthan acidified chitosan includes the following steps: 0.095 μL of chitosan was dispersed in 385 L of 25% sodium hydroxide solution and stirred at 500 rpm for 30 min to obtain the fifth mixture. The fifth mixture was added to 75 L of carbon disulfide and stirred at 300 rpm for 4 h at 40 °C to obtain the sixth mixture. The pH of the sixth mixture was adjusted to 7.0 with 25 wt% hydrochloric acid, and 1000 L of 95% methanol solution was added, causing a precipitate to form. After standing for 30 min, the supernatant was discarded, and the precipitate was retained. The precipitate was washed three times with 75% ethanol solution, and after each wash, it was centrifuged at 3000 rpm for 15 min to collect the precipitate. The precipitate was then washed twice with anhydrous ethanol. The product after the final wash was dried at 50 °C under a vacuum of -0.08 MPa for 24 h, and then ground to obtain xanthated chitosan. Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 8 is that the 0.095t xanthate-modified chitosan in Example 8 is replaced with 0.095t carboxymethyl chitosan. Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 8 is that the 0.2t lauramidopropyl dimethyl tertiary amine in Example 8 is replaced with 0.2t dodecyl dimethyl tertiary amine. Comparative Example 3

[0052] The difference between Comparative Example 3 and Example 8 is that 0.2t of modified stabilizer was replaced with 0t of modified stabilizer. Application examples

[0053] 10m 3 Wastewater from a lake polluted with heavy metals such as lead and copper (wastewater indicators: COD 82.6 mg / L, total phosphorus 1.1 mg / L, ammonia nitrogen 3.4 mg / L, water transmittance 65.8%) and 0.5 t of sludge from the bottom of the polluted lake were added to a simulated treatment tank at a concentration of 200 g / m³. 3 The sodium acetate solutions prepared in Examples 1-8 and Comparative Examples 1-3 were added, and air aeration was performed at a rate of 10 m³ / h. 3 / (m³・h), aeration time 4h, to fully activate the added sodium acetate capacity. After activation, aeration is performed every 8h, with each aeration time lasting 0.5h, to ensure sufficient dissolved oxygen content in the water. After continuous aeration for 10 days, the main water quality indicators of the simulated treatment tank are tested. Test Example 1

[0054] Antibacterial properties: Tested according to GB / T 38502-2020 "Laboratory Test Methods for the Bactericidal Efficacy of Disinfectants", the selected bacterial strains being Staphylococcus aureus ATCC 6538 (China Agricultural Microbiological Culture Collection Center) and Escherichia coli ACCC 04281 (China Agricultural Microbiological Culture Collection Center). First, a concentration of 1×10⁻⁶ needs to be prepared. 8 -5×10 8 A suspension of Staphylococcus aureus and Escherichia coli at CFU / mL was prepared, along with a 0.3% bovine serum albumin solution as an organic interfering agent to simulate a wastewater environment. Sodium acetate solutions prepared in Examples 1-8 and Comparative Examples 1-3 were diluted to 100 mg / L with standard hard water. Then, under 20°C water bath conditions, 0.5 mL of bacterial suspension, 0.5 mL of organic interfering agent, and 4.0 mL of sodium acetate solution were added sequentially to a sterile test tube. After thorough mixing and timing for 20 minutes, 0.5 mL of the mixture was immediately added to a test tube containing 4.5 mL of neutralizing agent (PBS solution containing 5 g / L sodium thiosulfate and 3 g / L Tween 80), mixed, and allowed to react for 10 minutes to terminate the activity of residual disinfectant. Finally, 1.0 mL of the neutralized sample was taken for further processing. Viable bacterial counts were performed (incubated at 36℃ for 48 hours). The experiment was repeated three times, with a positive control group (using deionized water instead of disinfectant) and a negative control group (containing only neutralizing agent and culture medium). The logarithmic kill value (KL) was calculated by comparing the average viable bacterial concentrations of the experimental group and the positive control group. The logarithmic kill value (KL) = (logarithmic value of average viable bacterial concentration in the positive control group - logarithmic value of viable bacterial concentration in the experimental group). The antibacterial rate (%) was expressed as [1 - 10⁻ᴷᴸ] × 100%. The test results are shown in Table 1.

[0055]

[0056] Test Example 2 Metal ion adsorption test: 1 g of wastewater treatment agent was added to 50 mL of a 20 mg / L lead ion solution at 25 °C, and the lead ion concentration was measured after 60 min. The test results are shown in Table 2.

[0057] Stability: Take 500 mL of sodium acetate solution sample and place it in a sealed polyethylene container. First, freeze it completely at -20℃ for 15 h. After freezing, remove the sample and thaw it naturally at 25℃ for 10 h. This is recorded as one freeze / thaw cycle. Repeat this operation until 5 cycles are completed. During the cycle, record the appearance of the sample before freezing and after thawing each time. After 5 cycles, use vacuum filtration (using a 0.45 μm filter membrane) to separate the precipitated solid crystals in the sample. After drying at 105℃ to constant weight, weigh the sample and calculate the crystallization rate. Crystallization rate = (mass of precipitated sodium acetate crystals / initial total mass of sodium acetate in the sample) × 100%. At the same time, use acid-base titration to detect the sodium acetate content in the sample and calculate the retention rate. Sodium acetate retention rate = (sodium acetate content after cycle / initial sodium acetate content) × 100%. The low-temperature stability is judged as qualified or unqualified if the crystallization rate is ≤0.5% and the sodium acetate retention rate is ≥98%. The test results are shown in Table 2.

[0058]

[0059] A comparative analysis of Examples 1-3 revealed that the sodium acetate solution prepared in Example 2 exhibited the best performance. This is likely due to the optimal mass ratio of sodium hexametaphosphate, glycidyl methacrylate, and lauramide propyl dimethylamine. The polyphosphate groups of sodium hexametaphosphate provide chelating sites and a dispersion framework, while the epoxy groups of glycidyl methacrylate act as bridges, enabling ring-opening reactions with the hydroxyl groups of sodium hexametaphosphate and the amino groups of lauramide propyl dimethylamine. The optimal mass ratio of these three components in Example 2 avoided the insufficient dosage in Example 1, which resulted in fewer quaternization active sites and reduced binding sites for the antibacterial component; it also prevented excessive cross-linking of the molecular chains caused by excessive dosage in Example 3, thus avoiding decreased dispersibility and uneven distribution of the subsequently prepared modified stabilizer in the sodium acetate solution. The quaternary ammonium salt surfactant generated at this ratio has a regular structure, which can efficiently achieve sodium-based modification when reacting with calcium-based montmorillonite, thereby enhancing the adsorption channels between montmorillonite layers. At the same time, it provides sufficient anchoring sites for the loaded chitosan derivative. Ultimately, in terms of antibacterial performance, the quaternary ammonium salt and antibacterial agent synergistically enhance the inhibitory effect on Staphylococcus aureus and Escherichia coli. In terms of heavy metal adsorption, the multiple components provide abundant chelation sites to reduce the concentration of lead ions. Moreover, the stabilizer is evenly dispersed, ensuring that the sodium acetate solution meets the low-temperature stability requirements, and the overall performance reaches the optimal level.

[0060] Comparative analysis of Examples 2 and 4-6 revealed that the sodium acetate solution prepared in Example 2 exhibited the best performance. This is likely due to the optimal mass ratio of calcium-based montmorillonite, quaternary ammonium surfactant, sodium silicate, and chitosan oligosaccharide. Calcium-based montmorillonite serves as the core carrier, the quaternary ammonium surfactant achieves sodium-based modification through cation exchange, sodium silicate enhances the interlayer stability of montmorillonite, and chitosan oligosaccharide provides antibacterial and heavy metal adsorption sites. The amount of quaternary ammonium surfactant used in Example 2 is moderate. It avoids the insufficient sodium-based modification of montmorillonite and narrow interlayer channels, which would reduce chitosan loading and active sites, as seen in Examples 4 and 5. It also prevents the excessive use in Example 6, which would lead to oversaturation of the montmorillonite surface charge, resulting in aggregation and reduced dispersibility and adsorption efficiency. At this ratio, the interlayer spacing of the modified montmorillonite is expanded, allowing for efficient loading of chitosan oligosaccharide. In terms of antibacterial properties, the quaternary ammonium salt and antibacterial agent synergistically enhance the inhibition rate against Staphylococcus aureus and Escherichia coli. In heavy metal adsorption, the interlayer channels of montmorillonite and the functional groups of chitosan derivatives work together to reduce lead ion concentration. The modified stabilizer is uniformly dispersed and effectively inhibits sodium acetate crystallization, ensuring the solution's low-temperature stability meets requirements.

[0061] Comparative analysis of Examples 2, 7-8, and Comparative Example 1 revealed that the sodium acetate solution prepared in Example 8 exhibited the best performance. This may be due to the use of different chitosan derivatives. Example 8 used xanthated chitosan. Xanthated chitosan introduces xanthic acid groups through the reaction of chitosan with carbon disulfide. These groups not only contain strong chelating sulfur-oxygen double bonds, forming stable cyclic chelates with lead ions and significantly improving the adsorption efficiency of lead ions and heavy metals, but also enhance the binding force between chitosan and intermediates, making the modified stabilizer structure more stable. In contrast, chitosan oligosaccharides have fewer chelating sites and weaker heavy metal adsorption capacity; carboxymethyl chitosan has greater steric hindrance due to its carboxymethyl group, resulting in lower binding efficiency with montmorillonite. Regarding antibacterial properties, the xanthic acid groups of xanthated chitosan can disrupt bacterial cell membrane permeability, and combined with the quaternary ammonium groups of quaternary ammonium salt surfactants, it exhibits high antibacterial rates against Staphylococcus aureus and Escherichia coli. In addition, xanthan acidified chitosan has better hydrophilicity and molecular flexibility, and can be uniformly dispersed in sodium acetate solution, inhibiting the precipitation of sodium acetate crystals during low-temperature freezing or thawing, thus ensuring good solution stability.

[0062] A comparative analysis of Example 8 and Comparative Example 2 revealed that the sodium acetate solution prepared in Example 8 exhibited better performance. This may be due to the use of different monomers containing tertiary amines. Example 8 demonstrated superior performance because it employed laurylamidopropyl dimethyl tertiary amine, which contains more amide groups than the dodecyl dimethyl tertiary amine in Comparative Example 2. These amide groups enhance the binding force with intermediates and xanthate-modified chitosan through hydrogen bonding, resulting in a more robust loading of the quaternary ammonium salt surfactant and reducing the loss of active components. The amide groups also increase the affinity for bacterial cell membranes, leading to a high antibacterial rate in the prepared sodium acetate solution. Furthermore, the modified stabilizer exhibited excellent dispersibility in the sodium acetate solution, ensuring its good stability.

[0063] A comparative analysis of Example 8 and Comparative Example 3 revealed that the sodium acetate solution prepared in Example 8 with the addition of a modified stabilizer was significantly more effective than that in Comparative Example 3 without the modified stabilizer. This is because the modified stabilizer is a composite system of an intermediate-loaded quaternary ammonium salt surfactant and xanthate-modified chitosan. It contains active functional groups such as quaternary ammonium groups and xanthate groups. The quaternary ammonium groups can disrupt bacterial cell membranes, while the xanthate groups can form stable chelates with lead ions, synergistically enhancing antibacterial and heavy metal adsorption effects. This results in a high antibacterial rate and reduced lead ion concentration for Staphylococcus aureus. Comparative Example 3, lacking these active sites, exhibited a low antibacterial rate and a high lead ion concentration. Furthermore, the layered structure and dispersion effect of the modified stabilizer inhibited the low-temperature crystallization of sodium acetate. In Comparative Example 3, without the modified stabilizer, sodium acetate easily precipitated, resulting in poor stability and a weak antibacterial effect. The modified stabilizer, through the synergistic effect of multiple components, comprehensively improves the overall performance of the sodium acetate solution.

[0064] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A sodium acetate solution, characterized in that, The preparation raw materials include sodium carbonate, water, acetic acid, antibacterial agent and modified stabilizer; the modified stabilizer includes calcium-based montmorillonite, quaternary ammonium salt surfactant, sodium agent, chitosan derivative; the mass ratio of the calcium-based montmorillonite, quaternary ammonium salt surfactant, sodium agent and chitosan derivative is 110: (5-10): (15-40): (75-130); the quaternary ammonium salt surfactant includes phosphorus-containing sodium salt, epoxy-containing monomer one and tertiary amine-containing monomer two.

2. The sodium acetate solution according to claim 1, characterized in that, The mass ratio of the phosphorus-containing sodium salt, epoxy-containing monomer one and tertiary amine-containing monomer two is 1: (2-4): (2-5).

3. The sodium acetate solution according to claim 1, characterized in that, The chitosan derivative is any one of chitooligosaccharide, hydroxypropyl chitosan and xanthated chitosan.

4. The sodium acetate solution according to claim 3, characterized in that, The preparation method of the xanthated chitosan includes the following steps: The chitosan is heated, stirred under alkaline condition, precipitate is separated out, the precipitate is washed and dried, and the xanthated chitosan is obtained.

5. The sodium acetate solution according to claim 1, characterized in that, The tertiary amine-containing monomer two is any one of lauryl amido propyl dimethyl tertiary amine and dodecyl dimethyl tertiary amine.

6. The sodium acetate solution of claim 1, wherein, The sodium agent is any one of sodium silicate and sodium pyrophosphate.

7. The sodium acetate solution according to claim 1, characterized in that, The preparation method of the modified stabilizer includes the following steps: S1, the calcium-based montmorillonite is dispersed in a solvent, the quaternary ammonium salt surfactant and sodium agent are added, heated, stirred, filtered, washed, dried, ground, and the intermediate is obtained; S2, the intermediate is dispersed in a solvent, an acid solution is added, the chitosan derivative is added, heated, stirred, centrifuged to obtain a solid, the solid is washed and dried, and the modified stabilizer is obtained.

8. The sodium acetate solution according to claim 7, characterized in that, The preparation method of the quaternary ammonium salt surfactant includes the following steps: The phosphorus-containing sodium salt is added into an acid solvent, the pH is adjusted to 2-4, the epoxy-containing monomer one is added, heated and stirred, the tertiary amine-containing monomer two is added, the pH is adjusted to 8-10, heated and stirred, and the quaternary ammonium salt surfactant is obtained.

9. The method of producing a sodium acetate solution according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: The water is heated, the sodium carbonate is added under stirring, the acetic acid is added, the pH is stirred until no change, water is added, stirred, the modified stabilizer and antibacterial agent are added, stirred, the pH is adjusted to 7.5-9, and the sodium acetate solution is obtained.

10. The application of the sodium acetate solution in any one of claims 1-8 in sewage treatment and water body regulation of aquaculture.

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