A sodium acetate solution, a preparation method and application thereof

Abstract

The application discloses a sodium acetate solution and a preparation method and application thereof, relates to the technical field of carbon source medicaments, and adopts sodium carbonate instead of traditional sodium hydroxide as an alkali source to prepare sodium acetate through a mild neutralization reaction, avoids the use of a strongly corrosive raw material and the generation of volatile organic compounds, and introduces a multifunctional modified stabilizer system. The system is composed of calcium-based montmorillonite, a quaternary ammonium salt surfactant, a sodiumizing agent and a chitosan derivative, and the stability of the sodium acetate solution is significantly improved through an intercalation modification process. The addition of the modified stabilizer not only enhances the anti-settling and anti-layering capacity 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 prone to breeding microorganisms and poor in stability during storage in a high-temperature and high-humidity environment. The preparation method can be widely applied to the fields of sewage treatment and aquaculture.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon source agents, in particular to a sodium acetate solution and a preparation method and application thereof. BACKGROUND

[0002] At present, in the field of sewage treatment, the supply of carbon source is the core link to realize biological denitrification and degradation of organic matter. Sodium acetate is widely used in the denitrification treatment process of municipal sewage and industrial wastewater due to its advantages of high carbon source purity, high microbial utilization rate and fast reaction speed. The preparation of traditional sodium acetate solution is mostly based on sodium hydroxide as an alkali source, which is generated by neutralization reaction of acetic acid and sodium hydroxide. However, this process has some problems. On the one hand, sodium hydroxide is a strong corrosive material, which requires special equipment for transportation and storage. In the reaction process, the local overheating can cause a sudden rise in system temperature, which not only increases energy consumption, but also can cause the volatilization of acetic acid to increase, resulting in a large amount of waste gas and environmental secondary pollution. On the other hand, the cost of sodium hydroxide raw material is relatively high, and the stability of the sodium acetate solution generated by the neutralization reaction is poor. During long-term storage, problems such as microbial growth and solution layering can easily occur, especially in high temperature and high humidity environments, which requires additional addition of preservatives, further increasing production and processing costs. To solve the above problems, the preparation process of sodium acetate with sodium carbonate as an alkali source has gradually become a research hotspot. Sodium carbonate not only has low corrosion and high safety, but also has a mild reaction process with acetic acid, which can effectively control the volatilization of VOCs.

[0003] At present, with the improvement of industrial park industrial agglomeration, the complexity of water quality faced by comprehensive sewage treatment plants is increasing, especially in industrial parks with high concentration of chemical industry, electronics and food processing. Higher requirements are put forward for the performance of sodium acetate carbon source. When multiple parks are concentrated in an area, such as the mixing of food processing wastewater, the number of bacteria contained in the sewage is high, and the total number of bacteria in the water body is higher in summer high temperature. The sewage treatment plant needs to add sodium acetate as a carbon source to improve the denitrification efficiency, but the traditional sodium acetate solution has some shortcomings in actual application. After being stored in an environment above 35℃ for more than 72 hours, the solution appears turbid and has an odor, and the microbial growth leads to a decrease in carbon source utilization rate, which requires frequent cleaning of the storage tank, affecting the continuity of treatment. At the same time, Cu²⁺ and Ni²⁺ in the sewage can easily accumulate in the biofilm, inhibiting microbial activity, shortening the membrane cleaning cycle to 15 days per time, and increasing the operation and maintenance cost. In addition, high concentration of bacteria in the sewage not only consumes part of the carbon source, but also can cause biological pollution of the membrane module, further reducing the treatment efficiency. SUMMARY

[0004] The purpose of the present 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 sewage treatment.

[0005] The first aspect of the application provides a sodium acetate solution, a preparation method and application thereof, which adopts the following technical scheme:

[0006] The sodium acetate solution comprises the following preparation raw materials: sodium carbonate, water, acetic acid, an antibacterial agent and a modified stabilizer; the modified stabilizer comprises calcium-based montmorillonite, a quaternary ammonium salt surfactant, a sodiumizing agent and a chitosan derivative; the mass ratio of the calcium-based montmorillonite, the quaternary ammonium salt surfactant, the sodiumizing agent and the chitosan derivative is 110: (5-10): (15-40): (75-130); the quaternary ammonium salt surfactant comprises a phosphorus-containing sodium salt, an epoxy-containing monomer one and a tertiary amine-containing monomer two.

[0007] By adopting the above technical scheme, sodium acetate is generated by reacting sodium carbonate and acetic acid, the reaction is mild, and the by-products are CO2 and water, which are easy to separate and purify, and the obtained solution has high purity and few impurities; meanwhile, the addition of the antibacterial agent can inhibit the breeding of microorganisms and prolong the shelf life of the solution. The modified stabilizer can significantly improve the stability and functionality of the sodium acetate solution. The calcium-based montmorillonite is subjected to the action of the sodiumizing agent, Na+ replaces Ca2+ in the interlayer to form an intermediate, the interlayer spacing is increased, and the adsorption capacity is enhanced. The phosphoric acid functional group provided by the phosphorus-containing sodium salt in the quaternary ammonium salt surfactant, the epoxy group of the epoxy-containing monomer one and the tertiary amine group of the tertiary amine-containing monomer two react, can intercalate into the interlayer of the montmorillonite, further expand the interlayer spacing and enhance the compatibility with the chitosan derivative; the chitosan derivative contains functional groups such as amino groups and hydroxyl groups, which can be combined with the active groups of the montmorillonite surface and the quaternary ammonium salt through hydrogen bonds and electrostatic attraction to construct a stable network structure, which not only improves the anti-settling and anti-layering capacity of the sodium acetate solution, but also endows it with certain thickening and film-forming functions. The components in the preparation of the modified stabilizer are matched in a mass ratio of 110: (5-10): (15-40): (75-130), so that the internal synergistic effect of the modified stabilizer is maximized, and finally the stability, functionality and storage of the sodium acetate solution are improved.

[0008] Optionally, the mass ratio of the phosphorus-containing sodium salt, the epoxy-containing monomer one and the tertiary amine-containing monomer two is 1: (2-4): (2-5).

[0009] By adopting the technical scheme, the phosphate functional group provided by the phosphorus-containing sodium salt is a reaction starting site, which first undergoes ring-opening reaction with the epoxy group in the monomer one, the ring structure of the epoxy group is broken under the nucleophilic attack of the phosphate, and an intermediate containing a hydroxyl group and a phosphate bond is formed; at this time, the amount of monomer one is controlled to ensure that each phosphorus-containing sodium salt molecule grafts sufficient epoxy ring-opening units, reserving sufficient active sites for subsequent quaternization reaction. The tertiary amine group in the monomer two containing the tertiary amine added subsequently will undergo quaternization reaction with the residual epoxy group or other active groups of the intermediate, and the nitrogen atom of the tertiary amine group will combine with the active carbon atom after the ring-opening of the epoxy group to form a quaternary ammonium salt structure. Under this proportion, the amount of the monomer containing the tertiary amine retains the hydrophilicity and coordination ability of the phosphate group, and introduces hydrophobicity and cationic activity through the quaternary ammonium salt group. Finally, the proportion makes the quaternary ammonium salt surfactant have good surface activity, dispersibility and stability at the same time, which is suitable for subsequent intercalation and synergistic effect with montmorillonite.

[0010] Optionally, the chitosan derivative is any one of chitooligosaccharide, hydroxypropyl chitosan or xanthated chitosan.

[0011] By adopting the technical scheme, the carboxyl group introduced by chitooligosaccharide can enhance the electrostatic binding force with the surface cations of montmorillonite, and the hydrophilicity of the carboxyl group can improve its dispersibility in sodium acetate solution, which is beneficial to the construction of a stable network. The hydroxypropyl group of hydroxypropyl chitosan is a flexible group, which can weaken the rigidity of the chitosan molecular chain, enhance the compatibility of the chitosan with the quaternary ammonium salt surfactant, reduce agglomeration and improve the uniformity of the stabilizer. The xanthate group of xanthated chitosan has both coordination and hydrophilicity, which can form a coordination bond with the metal ions between the layers of montmorillonite to strengthen the binding, further improve the anti-settling ability of the solution system through strong hydrophilicity, and also has heavy metal adsorption performance. In comparison, the electrostatic interaction of chitooligosaccharide is stronger, the compatibility of hydroxypropyl chitosan is better, and the coordination and hydrophilicity of xanthated chitosan are more prominent. All of them can improve the stability and functionality of the system through the interaction of functional groups with montmorillonite and quaternary ammonium salt.

[0012] Optionally, the preparation method of the xanthated chitosan comprises the following steps:

[0013] The chitosan and carbon disulfide are heated under alkaline conditions, stirred, and a precipitate is precipitated, washed and dried, to obtain xanthated chitosan.

[0014] By adopting the technical scheme, the chitosan and carbon disulfide are heated and stirred under alkaline conditions, the alkaline environment can make the amino and hydroxyl groups in the chitosan molecules form negative active sites, and the nucleophilic addition reaction with carbon disulfide occurs, and the xanthate group is efficiently introduced, which can be stably combined with the chitosan molecular chain; the subsequent steps of precipitation, washing and drying can accurately remove the unreacted carbon disulfide, alkaline by-products and other impurities, so as to avoid the influence of residual substances on the structural stability of the product, and finally the xanthated chitosan is obtained, which not only retains the original biological compatibility of chitosan, but also significantly improves the chelation, moisture absorption and biological adhesion performance due to the introduction of xanthate groups, and is suitable for heavy metal adsorption in sewage.

[0015] Optionally, the tertiary amine-containing monomer II is any one of lauryl amide propyl dimethyl tertiary amine and dodecyl dimethyl tertiary amine.

[0016] By adopting the technical scheme, lauryl amide propyl dimethyl tertiary amine and dodecyl dimethyl tertiary amine both contain tertiary amine functional groups, which endow the monomer with excellent basicity and nucleophilic reactivity. The former introduces an amide bond to enhance the polarity and biocompatibility of the molecule, and the latter's dodecyl hydrophobic chain highlights the hydrophobicity. Both of them can be functionally modified through quaternization reaction of the tertiary amine group. By selecting these two kinds of tertiary amine monomers, the controllability of the reaction can be ensured by relying on the tertiary amine functional groups, and different application scenarios can be adapted through structural differences.

[0017] Optionally, the sodium agent is any one of sodium silicate and sodium pyrophosphate.

[0018] By adopting the technical scheme, sodium silicate and sodium pyrophosphate are used as sodium agents, and the core advantage lies in that sodium ions can realize sodium modification of calcium-based montmorillonite. Sodium silicate contains silicate, and its anion can form a colloidal system, which can enhance the dispersibility and stability of the modified material. Sodium pyrophosphate contains pyrophosphate, which has stronger chelation ability for metal ions, and can reduce the interference of metal impurities during the sodium modification process.

[0019] Optionally, the preparation method of the modified stabilizer comprises the following steps:

[0020] S1, dispersing calcium-based montmorillonite in a solvent, adding a quaternary ammonium salt surfactant and a sodium agent, heating and stirring, filtering, washing, drying, and grinding to obtain an intermediate;

[0021] S2, dispersing the intermediate in a solvent, adding an acid solution, adding a chitosan derivative, stirring, centrifuging to obtain a solid, washing the solid, and drying to obtain the modified stabilizer.

[0022] By adopting the technical scheme, the sodium ions of the sodium agent in step S1 further strengthen the interlayer cation replacement, the quaternary ammonium group of the quaternary ammonium salt can be ion exchanged with the calcium ions in the interlayer of the calcium-based montmorillonite, the conversion from the calcium-based to the intermediate is realized, the interlayer spacing is widened, and the interface activity is improved. In step S2, the amino group of the chitosan derivative is protonated by the acid solution, so that the amino group is combined with the intermediate in the interlayer through electrostatic action and is anchored in the interlayer of the montmorillonite; and finally, the prepared modified stabilizer has both the layered structure stability and the interface adhesion.

[0023] Optionally, the preparation method of the quaternary ammonium salt surfactant comprises the following steps:

[0024] The phosphorus-containing sodium salt is added into an acid solvent, the pH is adjusted to 2-4, a monomer containing an epoxy group is added, heating and stirring are performed, a monomer containing a tertiary amine is added, the pH is adjusted to 8-10, heating and stirring are performed, and the quaternary ammonium salt surfactant is obtained.

[0025] By adopting the technical scheme, the acid condition activates the phosphorus-containing sodium salt, and the ring-opening reaction of the epoxy group of the monomer containing an epoxy group is introduced into the phosphorus-containing group; the pH is subsequently adjusted to be alkaline, which is beneficial to the reaction of the tertiary amine group of the monomer containing a tertiary amine with the active sites in the system, and the quaternization is completed. The prepared quaternary ammonium salt surfactant has both the phosphorus group and the quaternary ammonium group characteristics, and the surface activity and the dispersion performance are better.

[0026] In a second aspect, the sodium acetate solution and the preparation method and application thereof provided by the present application adopt the following technical scheme:

[0027] A preparation method of a sodium acetate solution comprises the following steps:

[0028] Water is heated, sodium carbonate is added under stirring, acetic acid is added, stirring is performed until the pH is unchanged, water is added, stirring is performed, a modified stabilizer and an antibacterial agent are added, stirring is performed, the pH is adjusted to 7.5-9, and the sodium acetate solution is obtained.

[0029] By adopting the technical scheme, the sodium carbonate and the acetic acid are reacted under heating and stirring, the hydrogen ions and the carbonate ions are gradually combined to generate carbon dioxide and water, the stirring is performed until the pH is unchanged to ensure that the reaction is complete and the raw materials are avoided to be left, the concentration is adjusted by adding water, and then the stabilizer and the antibacterial agent are added to inhibit the possible impurity ion agglomeration or component decomposition in the solution; finally, the pH is adjusted to a weak alkaline environment to maintain the dissociation balance of the sodium acetate, prevent the hydrolysis and deterioration of the sodium acetate, and also play a good antibacterial effect.

[0030] In a third aspect, the sodium acetate solution and the preparation method and application thereof provided by the present application adopt the following technical scheme:

[0031] The application of the sodium acetate solution in sewage treatment and water body regulation in aquaculture.

[0032] In this recipe, part of the raw materials and their role as follows:

[0033] Sodium carbonate: Sodium carbonate is the core raw material of sodium acetate, which contains carbonate that can react with the carboxyl group of acetic acid. Carbonate gradually combines with the hydrogen ion dissociated from acetic acid to generate carbon dioxide and sodium acetate. This reaction is mild and the byproduct is easy to separate, which not only guarantees the efficient generation of sodium acetate, but also avoids introducing additional impurities.

[0034] Water: Water is mainly used as a solvent in the preparation of sodium acetate solution, which can dissolve sodium carbonate, acetic acid and sodium acetate, so that the reactants can fully contact. At the same time, water promotes ion dissociation when heated and stirred, which helps the reaction of carbonate and acetic acid carboxyl group.

[0035] Acetic acid: Acetic acid is one of the core raw materials for preparing sodium acetate, which contains carboxyl groups that can react with the carbonate of sodium carbonate to generate carbon dioxide, water and sodium acetate.

[0036] Antibacterial agent: The main role of the antibacterial agent is to inhibit the growth of microorganisms in the sodium acetate solution to extend the shelf life. At the same time, the antibacterial agent can synergize with the chitosan derivative to resist bacteria. The functional groups such as amino groups of the chitosan derivative can adsorb microorganisms, enhancing the contact efficiency of the antibacterial agent and the microorganisms, and the two can synergize to further improve the antibacterial effect.

[0037] Calcium-based montmorillonite: Calcium-based montmorillonite is the core raw material for preparing modified stabilizer, which contains exchangeable calcium ions in the interlayer and a negative electric layer structure on the surface. In the modification, the calcium ions in the interlayer are ion-exchanged with sodium ions of the sodium agent, and can also be replaced by quaternary ammonium groups of the quaternary ammonium salt surfactant, and the interlayer spacing of the intermediate is significantly widened. This improves the anti-settling and anti-layering ability of the sodium acetate solution, and also has the effect of adsorbing impurities.

[0038] Sodium agent: The sodium agent in this application is sodium silicate. The core role is to realize the sodium modification of calcium-based montmorillonite. The sodium ions contained in the sodium agent can be ion-exchanged with the calcium ions in the interlayer of calcium-based montmorillonite, replacing the calcium ions to convert calcium-based montmorillonite into an intermediate, significantly widening the interlayer spacing and improving adsorption and interfacial activity. This process has no harmful byproducts, which not only optimizes the structure and performance of montmorillonite, but also lays a foundation for the subsequent intercalation of quaternary ammonium salt and combination of chitosan derivative.

[0039] Chitosan derivative: Chitosan derivative is the key functional component of the modified stabilizer, which contains functional groups such as amino and hydroxyl groups that can play multiple roles. The protonated amino groups in the acid solution can be combined with the negative groups on the surface of the intermediate through electrostatic attraction. The hydroxyl groups or other groups can also form hydrogen bonds with the quaternary ammonium salt surfactant. These effects make the chitosan derivative anchored in the interlayer of montmorillonite, building a stable network, which not only improves the anti-settling and anti-layering ability of the sodium acetate solution, but also endows the solution with heavy metal adsorption and other functions due to its hydrophilicity or coordination, ensuring the stability and functionality during the entire preparation process.

[0040] Phosphorus-containing sodium salt: The phosphorus-containing sodium salt in the present application is sodium hexametaphosphate. Sodium hexametaphosphate, as a phosphorus-containing sodium salt, is a key starting material for preparing quaternary ammonium salt surfactants. The phosphate functional group contained therein is activated under acidic conditions and initiates a nucleophilic attack on the epoxy group of the first epoxy-containing monomer, causing the epoxy ring structure to break, forming an intermediate containing a hydroxyl group and a phosphate ester bond, reserving an active site for subsequent quaternization. At the same time, the coordination ability of the phosphate group gives the final quaternary ammonium salt surfactant good dispersibility, allowing it to smoothly intercalate between the layers of montmorillonite, enhancing the compatibility with chitosan derivatives.

[0041] First epoxy-containing monomer: Under acidic conditions, the epoxy group will be attacked by the phosphate nucleophile of sodium hexametaphosphate, and the ring structure will be broken to form an intermediate containing a hydroxyl group and a phosphate ester bond, reserving an active site for subsequent reactions; then the active groups remaining in the intermediate react with the tertiary amine group of the second tertiary amine-containing monomer. Through the ring-opening and linking action of the epoxy group, the phosphorus group and the quaternary ammonium group are combined into the same molecule, giving the quaternary ammonium salt surfactant hydrophobicity and cationic activity.

[0042] Second tertiary amine-containing monomer: Under alkaline conditions, the nitrogen atom of the tertiary amine group acts as a nucleophilic center and undergoes quaternization with the intermediate formed after the ring-opening of the first epoxy-containing monomer, generating a quaternary ammonium salt structure. At the same time, its own amide bond or long alkyl chain gives the product polarity, biocompatibility and hydrophobicity, allowing the quaternary ammonium salt surfactant to have both cationic activity and be able to intercalate into montmorillonite efficiently.

[0043] In summary, the present application includes at least one of the following beneficial technical effects:

[0044] 1. Compared with the prior art, by reacting the phosphorus-containing sodium salt, the first epoxy-containing monomer and the second tertiary amine-containing monomer, the phosphate salt is activated and attacks the epoxy group under acidic conditions, and then the tertiary amine group completes quaternization under alkaline conditions, forming a surfactant with both phosphorus groups and quaternary ammonium salt structures. The phosphorus group gives the product excellent dispersibility and coordination ability, and the quaternary ammonium group provides cationic activity and hydrophobicity, allowing the surfactant to intercalate into the interlayer of montmorillonite efficiently, enhancing the compatibility with chitosan derivatives, and laying a foundation for building a stable functional system;

[0045] 2. Compared with the prior art, the modified stabilizer takes calcium-based montmorillonite as the core, is converted into an intermediate by a sodiumizing agent, and the interlayer spacing is significantly expanded; the quaternary ammonium salt surfactant intercalates into the interlayer by ion exchange, further strengthening the interfacial activity; the chitosan derivative is anchored in the interlayer through electrostatic attraction, hydrogen bonding and other actions, building a stable network structure. After the modified stabilizer is added to a sodium acetate solution, the anti-settling and anti-layering abilities of the system are significantly improved, and the system is also given antibacterial activity and heavy metal adsorption function, comprehensively enhancing the storage stability of the sodium acetate solution in complex environments. DETAILED DESCRIPTION

[0046] The parameters, sources of the specific chemicals used in the examples and comparative examples of the present application are as follows, and each raw material used is a commercially available product unless otherwise specified:

[0047] Chitosan, item number: S11064-500g, degree of deacetylation 90%, viscosity ≤500 cps, Shanghai Yuan Ye Biotechnology Co., Ltd.;

[0048] Glycidyl methacrylate, item number: S60373-500g, Shanghai Yuan Ye Biotechnology Co., Ltd.;

[0049] Chitooligosaccharide, item number: S31060-500g, MW <3000, brand: Yuan Ye;

[0050] Calcium-based montmorillonite, CAS number: 1302-78-9, Guangzhou Yifeng Chemical Technology Co., Ltd.;

[0051] Antibacterial agent, 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one, item number: CMIT / MIT-14, Weifang Yuke Chemical Co., Ltd. Example 1

[0052] A preparation method of a sodium acetate solution, comprising the following steps:

[0053] First step, preparation of a modified stabilizer.

[0054] 0.1 t of sodium hexametaphosphate solution is provided, and the pH is adjusted to 4 with a 10 wt% nitric acid solution, 0.3 t of glycidyl methacrylate is added, heated to 70°C, and stirred at 500 rpm for 2 h to obtain a first mixture. The first mixture is kept at a constant temperature of 70°C, 0.2 t of lauryl amido propyl dimethyl tertiary amine is mixed with the first mixture, the pH is adjusted to 8 with a 5 wt% sodium hydroxide aqueous solution, heated to 90°C, and stirred at 500 rpm for 3 h, and then dried at 60°C under a vacuum degree of -0.08 MPa for 10 h to obtain a quaternary ammonium salt surfactant.

[0055] 0.11 t of calcium-based montmorillonite is 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 are 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 is filtered to obtain a solid, the solid is washed with water for 3 times, the solid after the last water washing is dried at 60°C for 10 h, and then activated at 110°C for 0.5 h to obtain an activated solid. The activated solid is ground to obtain an intermediate.

[0056] 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 a 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 with water three times, dried at 60 °C under a vacuum degree of -0.08 MPa for 8 h, and ground to obtain a modified stabilizer.

[0057] In the second step, a sodium acetate solution was prepared.

[0058] 10 t of water was provided and the water temperature was controlled at 10 °C. 4 t of sodium carbonate was added, stirred at 500 rpm for 1 h to obtain a sodium carbonate solution. The sodium carbonate solution was added to 7.18 t of a 70 wt% acetic acid solution, stirred at 500 rpm for 1 h, and 0.2 t of the modified stabilizer and 0.1 t of 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one were added, stirred at 500 rpm for 1 h, and 70 wt% acetic acid solution was added to adjust the pH to 8 to obtain the sodium acetate solution. Example 2

[0059] The difference between this example 2 and example 1 is that 0.008 t of the quaternary ammonium salt surfactant in example 2 is replaced by 0.005 t of the quaternary ammonium salt surfactant. Example 3

[0060] The difference between this example 3 and example 1 is that 0.2 t of lauryl amido propyl dimethyl tertiary amine in example 1 is replaced by 0.4 t of lauryl amido propyl dimethyl tertiary amine. Example 4

[0061] The difference between this example 4 and example 2 is that 0.008 t of the quaternary ammonium salt surfactant is replaced by 0.005 t of the quaternary ammonium salt surfactant. Example 5

[0062] The difference between this example 5 and example 2 is that 0.008 t of the quaternary ammonium salt surfactant is replaced by 0.007 t of the quaternary ammonium salt surfactant. Example 6

[0063] The difference between this example 6 and example 2 is that 0.008 t of the quaternary ammonium salt surfactant is replaced by 0.01 t of the quaternary ammonium salt surfactant. Example 7

[0064] This example 7 differs from example 2 in that 0.095t chitooligosaccharide is replaced by 0.095t hydroxypropyl chitosan. Example 8

[0065] This example 8 differs from example 2 in that 0.095t chitooligosaccharide is replaced by 0.095t xanthated chitosan.

[0066] The preparation method of the xanthated chitosan comprises the following steps:

[0067] The 0.095t chitosan is dispersed in 385L of 25% sodium hydroxide solution, stirred at 500rpm for 30min to obtain a fifth mixture. The fifth mixture is added into 75L of carbon disulfide, stirred at 300rpm for 4h at 40℃ to obtain a sixth mixture. The sixth mixture is adjusted to pH 7.0 with 25wt% hydrochloric acid, 1000L of 95% methanol solution is added, and the precipitate is separated after standing for 30min, and the supernatant is discarded, and the precipitate is reserved. The precipitate is washed with 75% ethanol solution for three times, and the precipitate is collected by centrifugation at 3000rpm for 15min after each washing, and the precipitate is washed with anhydrous ethanol for two times, and the product after the last washing is dried at 50℃ under a vacuum degree of -0.08MPa for 24h, and ground to obtain the xanthated chitosan. Comparative example 1

[0068] This comparative example 1 differs from example 8 in that the 0.095t xanthated chitosan in example 8 is replaced by 0.095t carboxymethyl chitosan. Comparative example 2

[0069] This comparative example 2 differs from example 8 in that the 0.2t lauryl amido propyl dimethyl tertiary amine in example 8 is replaced by 0.2t dodecyl dimethyl tertiary amine. Comparative example 3

[0070] This comparative example 3 differs from example 8 in that the 0.2t modified stabilizer is replaced by 0t modified stabilizer.

[0071] Application example

[0072] 10m 3 The polluted lake sewage (sewage indexes are COD 82.6mg / L, total phosphorus 1.1mg / L, ammonia nitrogen 3.4mg / L, and water transmittance 65.8%) containing heavy metals such as lead and copper, and 0.5t of the bottom sludge of the polluted lake are put into a simulated treatment tank, and 200g / m 3 The sodium acetate solution prepared in examples 1-8 and comparative examples 1-3 is added, and air aeration is carried out, and the aeration amount is 10m 3(m3.h), aeration time 4h, fully activate the capacity of sodium acetate added. After activation, every 8h, aeration was carried out for 0.5h, to ensure that the water dissolved oxygen content was sufficient. After 10 days of continuous aeration, the main water quality indicators of the simulation treatment pool were detected.

[0073] Test Example 1

[0074] Antibacterial performance: tested according to GB / T 38502-2020 "Laboratory disinfectant germicidal efficacy test method", and the selected bacteria were Staphylococcus aureus ATCC 6538 (China Agricultural Microbial Culture Collection Center) and Escherichia coli ACCC 04281 (China Agricultural Microbial Culture Collection Center). First, 1x10 8 -5x10 8 CFU / mL of Staphylococcus aureus and Escherichia coli bacterial suspension was prepared, and 0.3% bovine serum albumin solution was prepared as an organic interferent to simulate sewage environment, and the sodium acetate solution samples prepared by Examples 1-8 and Comparative Examples 1-3 were diluted to 100 mg / L with standard hard water; then under the condition of 20℃ water bath, 0.5mL bacterial suspension, 0.5mL organic interferent and 4.0mL sodium acetate solution were added into a sterile test tube in turn, mixed thoroughly and started timing, 20min later, 0.5mL mixed solution was taken and added into a test tube containing 4.5mL neutralizing agent (5g / L sodium thiosulfate and 3g / L Tween 80 in PBS solution), mixed and acted for 10min to terminate the activity of residual disinfectant, finally, 1.0mL neutralized sample was taken for viable culture counting (36℃ incubation for 48h), the test was repeated for 3 times and the positive control group (using deionized water instead of disinfectant) and negative control group (containing only neutralizing agent and culture medium) were set synchronously, finally, the average viable concentration of the experimental group and the positive control group was compared to calculate the killing logarithm value (KL), KL=(logarithm value of average viable concentration of positive control group-logarithm value of viable concentration of experimental group), and the antibacterial rate (%)=[1-10⁻ᴷᴸ]x100% to represent the antibacterial rate. The test results are shown in Table 1.

[0075]

[0076] Test Example 2

[0077] Metal ion adsorption test: 1g of sewage treatment agent was added to 50mL of lead ion solution with a concentration of 20mg / L at 25℃, and the lead ion concentration was detected after 60min. The test results are shown in Table 2.

[0078] Stability: Take 500 mL of sodium acetate solution sample, place the sample in a sealed polyethylene container, first freeze completely at -20℃ for 15h; after freezing is completed, take out the sample and place it at 25℃ for natural thawing for 10h, record the sample appearance state before freezing and after thawing during the cycle process, after 5 cycles, separate the solid crystals precipitated from the sample by filtration method (using 0.45μm filter membrane), dry at 105℃ to constant weight, then weigh and calculate the crystallization rate. Crystallization rate = (mass of precipitated sodium acetate crystals / total mass of initial sodium acetate in the sample) x 100%. At the same time, detect the sodium acetate content in the sample by acid-base titration method and calculate the retention rate. Sodium acetate retention rate = (sodium acetate content after cycle / initial sodium acetate content) x 100%, within the range of crystallization rate ≤0.5% and sodium acetate retention rate ≥98% is the pass criterion for low-temperature stability. The test results are shown in Table 2.

[0079]

[0080] Comparative analysis of Examples 1-3 shows that the sodium acetate solution prepared in Example 2 has the best performance. The possible reason is that the mass ratio of sodium hexametaphosphate, glycidyl methacrylate and lauryl amido propyl dimethyl tertiary amine is optimal. The polyphosphate of sodium hexametaphosphate can provide chelation sites and dispersion skeleton, the epoxy group of glycidyl methacrylate acts as a bridge and can undergo ring-opening reaction with the hydroxyl group of sodium hexametaphosphate and the amino group of lauryl amido propyl dimethyl tertiary amine. The mass ratio of the three in Example 2 avoids the insufficient amount of quaternary ammonium active sites in Example 1, reducing the antibacterial component binding sites; it also prevents excessive cross-linking of molecular chains in Example 3, avoiding the decrease in dispersibility leading to uneven distribution of the subsequently prepared modified stabilizer in the sodium acetate solution. The structure of the quaternary ammonium surfactant generated under this ratio is regular, and when it interacts with calcium-based montmorillonite, it can efficiently achieve sodium-based modification, improving the interlayer adsorption channel of montmorillonite; at the same time, it provides sufficient anchoring sites for loading chitosan derivatives, ultimately achieving synergistic enhancement of the inhibition effect of quaternary ammonium salt and antibacterial agent on Staphylococcus aureus and Escherichia coli in terms of antibacterial performance; in terms of heavy metal adsorption, the multiple components provide rich chelation sites to reduce the concentration of lead ions; and the stabilizer is uniformly dispersed, ensuring the low-temperature stability of the sodium acetate solution to be qualified, and the comprehensive performance is optimal.

[0081] Comparative analysis of Examples 2, 4-6 found that the sodium acetate solution prepared in Example 2 had the best performance. The possible reason is that the mass ratio of calcium-based montmorillonite, quaternary ammonium salt surfactant, sodium silicate and chitosan oligosaccharide is optimal. Calcium-based montmorillonite is the core carrier, quaternary ammonium salt surfactant is modified to sodium-based by cation exchange, sodium silicate can enhance the stability of the interlayer of montmorillonite, and chitosan oligosaccharide provides antibacterial and heavy metal adsorption sites. The amount of quaternary ammonium salt surfactant in Example 2 is moderate. It not only avoids the insufficient sodium-based modification of montmorillonite in Examples 4 and 5, which narrows the interlayer channel and reduces the loading capacity and active sites of chitosan. It also prevents the excessive use of montmorillonite in Example 6, which causes the surface charge of montmorillonite to be oversaturated, resulting in agglomeration, reduced dispersibility and adsorption efficiency. Under this ratio, the interlayer spacing of montmorillonite is expanded after modification, and chitosan oligosaccharide can be efficiently loaded. In terms of antibacterial performance, quaternary ammonium salt and antibacterial agent synergistically improve the inhibition rate of Staphylococcus aureus and Escherichia coli; in heavy metal adsorption, the interlayer channel of montmorillonite and the functional groups of chitosan derivatives work together to reduce the concentration of lead ions. The modified stabilizer is uniformly dispersed, which can effectively inhibit the crystallization of sodium acetate and ensure the low-temperature stability of the solution to be qualified.

[0082] Comparative analysis of Examples 2, 7-8 and Comparative Example 1 found that the sodium acetate solution prepared in Example 8 had the best performance. The possible reason is the use of different chitosan derivatives. Xanthated chitosan is used in Example 8. Xanthated chitosan introduces xanthate groups by reacting chitosan with carbon disulfide. This group not only contains a strong chelating ability of sulfur-oxygen double bond, which can form a stable ring chelate with lead ions, greatly improving the heavy metal adsorption efficiency of lead ions; at the same time, the xanthate group can enhance the binding force between chitosan and intermediates, making the structure of the modified stabilizer more stable. In contrast, chitosan oligosaccharide has fewer chelating sites and weaker heavy metal adsorption capacity; the steric hindrance of carboxymethyl chitosan is larger, and the combination efficiency with montmorillonite is low. In terms of antibacterial performance, the xanthate group of xanthated chitosan can destroy the permeability of the bacterial cell membrane, and the quaternary ammonium group of the quaternary ammonium salt surfactant has high antibacterial rate for Staphylococcus aureus and Escherichia coli. In addition, xanthated chitosan has better hydrophilicity and molecular flexibility, and can be uniformly dispersed in the sodium acetate solution, inhibiting the crystallization of sodium acetate during the low-temperature freezing or thawing process, and ensuring good solution stability.

[0083] Comparative analysis of Example 8 and Comparative Example 2 shows that the sodium acetate solution prepared in Example 8 has better performance. The possible reason is that different tertiary amine-containing monomers are used. The performance of Example 8 is better because lauryl amide propyl dimethyl tertiary amine is used, which contains more amide groups than the dodecyl dimethyl tertiary amine of Comparative Example 2. The group enhances the binding force with the intermediate and xanthated chitosan through hydrogen bonding, making the quaternary ammonium salt surfactant more firmly loaded, reducing the loss of active components. The amide group improves the affinity with the bacterial cell membrane, so that the prepared sodium acetate solution has high antibacterial rate, and the modified stabilizer has good dispersibility in the sodium acetate solution, ensuring good stability of the sodium acetate solution.

[0084] Comparative analysis of Example 8 and Comparative Example 3 shows that the sodium acetate solution prepared in Example 8 has a significantly better effect of adding a modified stabilizer than Comparative Example 3 without adding a modified stabilizer. Because the modified stabilizer is a composite system of the intermediate loaded quaternary ammonium salt surfactant and xanthated chitosan. It contains active functional groups such as quaternary ammonium groups and xanthate groups. The quaternary ammonium group can destroy the bacterial cell membrane, and the xanthate group can form a stable chelate with lead ions, which synergistically improves the antibacterial and heavy metal adsorption effects, so that the antibacterial rate of Staphylococcus aureus is high and the lead ion concentration is low. Without these active sites in Comparative Example 3, the antibacterial rate is low and the lead ion concentration is high. At the same time, the layered structure and dispersion effect of the modified stabilizer can inhibit the low-temperature crystallization of sodium acetate; without the modified stabilizer in Comparative Example 3, sodium acetate is easy to precipitate, has poor stability, and has poor antibacterial effect. The modified stabilizer improves the comprehensive performance of the sodium acetate solution through the synergistic effect of multiple components.

[0085] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, any equivalent changes made on the basis of the structure, shape, and principle of the present application should be covered within the protection scope of the present 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 raw material of the quaternary ammonium salt surfactant includes phosphorus-containing sodium salt, epoxy-containing monomer one and tertiary amine-containing monomer two; The modified stabilizer is prepared by the following preparation method: S1, dispersing the calcium-based montmorillonite in a solvent, adding the quaternary ammonium salt surfactant and the sodium agent, heating, stirring, filtering, washing, drying and grinding to obtain an intermediate; S2, dispersing the intermediate in a solvent, adding an acid solution and the chitosan derivative, heating, stirring, centrifuging to obtain a solid, washing the solid and drying to obtain the modified stabilizer; The sodium acetate solution is prepared by the following preparation method: 4 parts of sodium carbonate are added into 10 parts of water to obtain a sodium carbonate solution; after the sodium carbonate solution is added into 7.18 parts of 70wt% acetic acid solution and stirred, acetic acid is added to adjust the pH to 9 to obtain a mixture; after the mixture is added into 9.85 parts of water and stirred, 0.2 parts of the modified stabilizer and 0.1 parts of the antibacterial agent are added and stirred, and then 70wt% acetic acid solution is added to adjust the pH to 8.

2. The sodium acetate solution according to claim 1, characterized in that, The mass ratio of the phosphorus-containing sodium salt, the epoxy-containing monomer one and the 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 xanthated chitosan is prepared by the following preparation method: Chitosan and carbon disulfide are heated under alkaline conditions, stirred, and a precipitate is precipitated, the precipitate is washed and dried to obtain the xanthated chitosan.

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 quaternary ammonium salt surfactant is prepared by the following preparation method: 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 to obtain the quaternary ammonium salt surfactant.

8. The sodium acetate solution according to any one of claims 1-7 is applied in sewage treatment and water body regulation of aquaculture.

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