A sodium formate-based deicing agent, and a preparation method and application thereof

Abstract

This application provides an antifreeze agent based on sodium formate, its preparation method, and its application. The preparation method of the antifreeze agent includes the following steps: Step S1: Dissolving a zirconium-based metal salt and an organic ligand in an organic solvent, and forming a framework structure between zirconium ions and the organic ligand through a solvothermal reaction to obtain a MOF material; wherein the organic ligand includes at least one of 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid; Step S2: Activating the carboxyl groups on a polycarboxylate superplasticizer, and reacting it with the amino groups on the MOF material to obtain a polycarboxylate-modified MOF material; Step S3: Immersing the polycarboxylate-modified MOF material in an aqueous sodium salt solution, allowing the sodium salt to be adsorbed and loaded onto the polycarboxylate-modified MOF material to obtain the antifreeze agent; wherein the sodium salt includes sodium formate. The antifreeze agent obtained by this method has good long-lasting antifreeze and water-reducing effects, and can be used to prepare novel wall materials with good antifreeze capabilities.

Description

Technical Field

[0001] This application belongs to the field of antifreeze production technology, specifically relating to an antifreeze based on sodium formate, its preparation method, and its application. Background Technology

[0002] With the development of construction engineering technology, the construction of concrete projects in frigid regions is receiving increasing attention. In low-temperature environments, the hydration reaction of concrete is slow, and early strength development is insufficient, making it highly susceptible to external factors such as freeze-thaw cycles, thus reducing the durability of the project. Therefore, developing efficient, environmentally friendly, and economical concrete antifreeze agents is of great significance.

[0003] Existing antifreeze agents mainly include chloride salts (such as calcium chloride) and organic antifreeze agents. Although calcium chloride has good antifreeze properties, its high corrosiveness poses a threat to the durability of reinforced concrete structures; while some organic antifreeze agents are limited due to their high cost and environmental pollution issues. In addition, some traditional antifreeze agents may affect the hydration process of concrete in low-temperature environments, resulting in unsatisfactory early strength development, which in turn affects the progress and quality of the project.

[0004] In recent years, sodium formate has gradually attracted attention due to its low corrosivity, good environmental friendliness, and certain hydration-promoting effect. Sodium formate can decompose into Na+ in cement paste. + and formate ions (HCOO) - These ions can regulate the surface charge of cement particles and promote particle dispersion, thus playing a role in water reduction to some extent. Simultaneously, sodium formate has antifreeze effects in low-temperature environments, helping to improve winter construction conditions. However, the mainstream method for using sodium formate as a concrete antifreeze agent is still to add it to concrete as an antifreeze component. However, sodium formate is easily soluble in water and releases too quickly into the concrete system, easily leaching away and failing to effectively exert its long-term antifreeze and water-reducing effects. Therefore, it is necessary to optimize the preparation process of sodium formate-based antifreeze agents to improve these problems.

[0005] Patent CN110423038A discloses a water-reducing agent and its preparation method, an antifreeze agent and its uses, and concrete. The antifreeze agent is prepared by blending a water-reducing agent with a non-oxidizing salt. The water-reducing agent includes isopentenyl alcohol polyoxyethylene ether and allyl alcohol polyoxyethylene ether, and at least one of acrylic acid and maleic anhydride. The molar ratio of isopentenyl alcohol polyoxyethylene ether to allyl alcohol polyoxyethylene ether is 1:0.8. The non-oxidizing salt includes sodium formate and sodium thiocyanate. However, this antifreeze agent, by blending sodium formate with the water-reducing agent and other additives, does not effectively solve the problem of rapid release and easy loss of sodium formate.

[0006] Therefore, there is a need to provide a sodium formate-based antifreeze agent with good long-lasting antifreeze and water-reducing effects. Summary of the Invention

[0007] In view of this, this application provides an antifreeze based on sodium formate, its preparation method and application. The antifreeze, through the slow release of sodium formate and its structural optimization, can achieve good long-lasting antifreeze and water reduction effects.

[0008] In a first aspect, this application provides a method for preparing a sodium formate-based antifreeze, comprising the following steps:

[0009] Step S1: Dissolve zirconium-based metal salt and organic ligand in an organic solvent, and form a framework structure between zirconium ions and organic ligand through a solvothermal reaction to obtain MOF material; wherein, the organic ligand includes at least one of 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid;

[0010] Step S2: After activating the carboxyl groups on the polycarboxylate superplasticizer, react it with the amino groups on the MOF material to obtain the polycarboxylate modified MOF material;

[0011] Step S3: Immerse the polycarboxylate-modified MOF material in an aqueous sodium salt solution to allow the sodium salt to be adsorbed and loaded onto the polycarboxylate-modified MOF material, thereby obtaining an antifreeze agent; wherein the sodium salt includes sodium formate.

[0012] Based on this application, in order to overcome the problem of sodium formate being released too quickly and easily lost during concrete preparation in related technologies, the inventors prepared an aminated zirconium-based MOF material. The zirconium-based MOF material has a good specific surface area, providing a large number of adsorption sites for sodium formate adsorption, thus effectively loading sodium formate. Simultaneously, the zirconium-based MOF material has high chemical stability, maintaining a stable structure even in the high pH environment of concrete, reducing premature release of sodium formate due to MOF material disintegration. The pore structure of the zirconium-based MOF material also limits the diffusion rate of sodium formate, achieving a slow-release effect. Furthermore, the organic ligand used is amino-containing terephthalic acid, resulting in a zirconium-based MOF material with active amino groups. By activating the carboxyl groups on the polycarboxylate superplasticizer, an amidation reaction occurs with the amino groups on the MOF material, thereby grafting amino groups onto the surface of the MOF material. Polycarboxylate superplasticizer; the polycarboxylate superplasticizer on the surface of MOF material still contains unreacted carboxyl groups, which are adsorbed onto the surface of cement particles during cement hydration, giving the MOF material itself a certain water-reducing effect. The synergistic release of sodium formate continuously improves the dispersibility of cement paste, thereby effectively increasing the water reduction rate. On the other hand, the polycarboxylate superplasticizer grafted onto the MOF surface is equivalent to forming a "flexible protective layer" on the surface, which can promote the dispersion of MOF material in concrete paste and adjust the release rate of sodium formate, reducing the decrease in fluidity caused by excessive sodium formate treatment. Simultaneously, because this antifreeze agent can release sodium formate slowly and effectively, combined with the polycarboxylate superplasticizer on the MOF material surface, it can reduce the internal porosity and capillary volume of concrete by making cement particles more uniformly dispersed. Combined with sodium formate, it can lower the freezing point of water, effectively reducing the damage to the internal structure of concrete caused by freeze-thaw cycles. Therefore, the antifreeze agent obtained by this method has good long-term antifreeze and water-reducing effects.

[0013] In some embodiments, step S1 specifically includes: dissolving 5 parts of zirconium-based metal salt, 7-15 parts of organic ligand and 20-50 parts of glacial acetic acid in 300-600 parts of N,N-dimethylformamide, and reacting in a high-pressure reactor at 115-130°C for 18-30 hours to obtain MOF material.

[0014] In some of the above embodiments, the MOF material prepared under the above conditions has a more uniform pore structure, which can further increase the loading of sodium formate in the MOF material, thereby giving the antifreeze a better long-lasting antifreeze and water-reducing effect.

[0015] In some embodiments, the zirconium-based metal salt comprises ZrOCl2·8H2O.

[0016] In some of the above embodiments, using ZrOCl2·8H2O as a zirconium-based metal salt, compared with using ZrCl4 as a zirconium-based metal salt, can reduce the chloride ion content in the MOF material, thereby reducing the chloride content in the antifreeze agent and reducing its impact on concrete performance.

[0017] In some embodiments, the organic ligand comprises 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid, wherein the mass ratio of 2-aminoterephthalic acid to 2,5-diaminoterephthalic acid is 1:0.2 to 0.5.

[0018] Based on the above embodiments, the inventors discovered that the choice of organic ligands affects the long-term antifreeze and water-reducing effects of antifreeze. When using 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:0.2 to 0.5 as organic ligands, the antifreeze exhibits better long-term antifreeze and water-reducing effects. This may be because different mass ratios of 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid affect the amino content on the surface of the MOF material, which in turn affects the crosslinking density with the polycarboxylate superplasticizer, thus affecting the release rate of sodium formate and consequently the performance of the antifreeze. Furthermore, different organic ligands also affect the coordination environment of zirconium ions, thereby influencing the pore structure of the MOF material and also impacting the performance of the antifreeze.

[0019] In some embodiments, step S2 specifically includes: dissolving 1-3 parts of polycarboxylate superplasticizer, 0.1-0.3 parts of EDC and 0.1-0.3 parts of NHS in 300-600 parts of buffer solution with pH 5-6.5, then adding 5 parts of MOF material, and reacting for 4-8 hours to obtain polycarboxylate modified MOF material.

[0020] In some of the above embodiments, by activating the polycarboxylate superplasticizer with EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) and NHS (N-hydroxysuccinimide), the carboxyl groups on the surface of the polycarboxylate superplasticizer can be made to have good reactivity, and can undergo amidation reaction with the amino groups on the surface of the MOF material at room temperature, thereby grafting the polycarboxylate superplasticizer onto the MOF material to obtain a polycarboxylate modified MOF material.

[0021] It is understandable that polycarboxylic acid can promote the dispersion of MOF materials and regulate the release rate of sodium formate by forming a "flexible protective layer" on the MOF material. On the other hand, polycarboxylic acid can also provide more sites for sodium formate adsorption and binding on the MOF material (through electrostatic, hydrogen bonding and other forces), thereby increasing the loading of antifreeze on sodium formate.

[0022] It should be noted that the sodium formate loading in the antifreeze can be roughly determined by thermogravimetric analysis (TGA). Specifically, TGA is performed on the unadsorbed polycarboxylate-modified MOF material to obtain the grafting content of the polycarboxylate superplasticizer in the antifreeze; then, TGA is performed on the antifreeze with adsorbed sodium formate to obtain the total mass of the polycarboxylate superplasticizer and sodium formate in the antifreeze. Subtracting the two yields the sodium formate loading in the antifreeze. As an example, the sodium formate loading in the antifreeze of one embodiment of this application is 25.8 wt%.

[0023] In some embodiments, step S3 specifically includes: immersing 5 parts of polycarboxylate-modified MOF material in 300-600 parts of sodium salt aqueous solution for 24-36 hours to obtain an antifreeze agent; wherein the sodium salt aqueous solution contains 20%-40% sodium formate by mass.

[0024] In some of the above embodiments, under the above conditions, the polycarboxylate-modified MOF material can be fully loaded with sodium formate, thereby increasing the sodium formate loading in the antifreeze and thus giving the antifreeze a better long-lasting antifreeze and water-reducing effect.

[0025] In some embodiments, the sodium salt aqueous solution further includes sodium phosphate, wherein the mass fraction of sodium phosphate in the sodium salt aqueous solution is 2% to 5%.

[0026] In some of the above embodiments, the inventors discovered that loading an appropriate amount of sodium phosphate into the antifreeze during the loading of sodium formate can further improve the performance of the antifreeze. The reason may be that loading an appropriate amount of sodium phosphate into the antifreeze allows sodium ions to slow down the dissolution of sodium formate through ion competition, and the leached phosphate ions can form a weak complex with sodium formate, which can increase the residence time of sodium formate in the antifreeze, thereby controlling the release rate of sodium formate in the antifreeze and giving the antifreeze a better long-lasting antifreeze and water-reducing effect.

[0027] Secondly, this application provides a sodium formate-based antifreeze, prepared according to the method described in any embodiment of the first aspect.

[0028] According to this application, since the antifreeze is obtained by the method described in any embodiment of the first aspect, it has the beneficial effects of the first aspect.

[0029] Thirdly, this application provides a concrete building material, including the antifreeze agent described in any embodiment of the second aspect.

[0030] According to this application, it includes an antifreeze agent according to any embodiment of the second aspect, which has good long-lasting antifreeze and water-reducing effects, and can make concrete building materials have higher strength and antifreeze ability, thus enabling the concrete building materials to be used as new wall materials with better antifreeze ability.

[0031] In some embodiments, the dosage of the antifreeze agent is 0.5% to 2.5% of the cement dosage. Based on the above embodiments, when the dosage of the antifreeze agent is within the above range, it can better exert its water-reducing and long-term antifreeze effects, giving concrete building materials better strength and antifreeze resistance. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0033] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this application, unless otherwise specified, "parts" refers to "parts by mass".

[0036] The solution of this application will be described below with reference to the following specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available products, and the devices or equipment used are all purchased from conventional market sales channels.

[0037] Polycarboxylate superplasticizer, purchased from Kron Chemicals, high-performance polycarboxylate superplasticizer SPC-100.

[0038] Example 1

[0039] Preparation of antifreeze based on sodium formate:

[0040] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, and then 8 parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:0.2.

[0041] Two parts of polycarboxylate superplasticizer were dissolved in 450 parts of MES buffer at pH 5.5, and then 0.15 parts of EDC and 0.15 parts of NHS were added. The mixture was stirred and activated at room temperature for 30 min. Five parts of MOF material were ultrasonically dispersed in 50 parts of MES buffer at pH 5.5 and mixed with the activated polycarboxylate superplasticizer solution. The mixture was reacted at room temperature for 6 h, centrifuged, washed three times with water, and then washed three times with ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the polycarboxylate modified MOF material.

[0042] Five parts of polycarboxylate-modified MOF material were immersed in 400 parts of sodium salt aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and vacuum dried at 60°C for 12 hours to obtain the antifreeze. The sodium salt aqueous solution contained 35% sodium formate and 3.5% sodium phosphate.

[0043] Example 2

[0044] Preparation of antifreeze based on sodium formate:

[0045] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, and then eight parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:0.5.

[0046] Two parts of polycarboxylate superplasticizer were dissolved in 450 parts of MES buffer at pH 5.5, and then 0.15 parts of EDC and 0.15 parts of NHS were added. The mixture was stirred and activated at room temperature for 30 min. Five parts of MOF material were ultrasonically dispersed in 50 parts of MES buffer at pH 5.5 and mixed with the activated polycarboxylate superplasticizer solution. The mixture was reacted at room temperature for 6 h, centrifuged, washed three times with water, and then washed three times with ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the polycarboxylate modified MOF material.

[0047] Five parts of polycarboxylate-modified MOF material were immersed in 400 parts of sodium salt aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and vacuum dried at 60°C for 12 hours to obtain the antifreeze. The sodium salt aqueous solution contained 35% sodium formate and 3.5% sodium phosphate.

[0048] Example 3

[0049] Preparation of antifreeze based on sodium formate:

[0050] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, then eight parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid.

[0051] Two parts of polycarboxylate superplasticizer were dissolved in 450 parts of MES buffer at pH 5.5, and then 0.15 parts of EDC and 0.15 parts of NHS were added. The mixture was stirred and activated at room temperature for 30 min. Five parts of MOF material were ultrasonically dispersed in 50 parts of MES buffer at pH 5.5 and mixed with the activated polycarboxylate superplasticizer solution. The mixture was reacted at room temperature for 6 h, centrifuged, washed three times with water, and then washed three times with ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the polycarboxylate modified MOF material.

[0052] Five parts of polycarboxylate-modified MOF material were immersed in 400 parts of sodium salt aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and vacuum dried at 60°C for 12 hours to obtain the antifreeze. The sodium salt aqueous solution contained 35% sodium formate and 3.5% sodium phosphate.

[0053] Example 4

[0054] Preparation of antifreeze based on sodium formate:

[0055] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, and then 8 parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:1.

[0056] Two parts of polycarboxylate superplasticizer were dissolved in 450 parts of MES buffer at pH 5.5, and then 0.15 parts of EDC and 0.15 parts of NHS were added. The mixture was stirred and activated at room temperature for 30 min. Five parts of MOF material were ultrasonically dispersed in 50 parts of MES buffer at pH 5.5 and mixed with the activated polycarboxylate superplasticizer solution. The mixture was reacted at room temperature for 6 h, centrifuged, washed three times with water, and then washed three times with ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the polycarboxylate modified MOF material.

[0057] Five parts of polycarboxylate-modified MOF material were immersed in 400 parts of sodium salt aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and vacuum dried at 60°C for 12 hours to obtain the antifreeze. The sodium salt aqueous solution contained 35% sodium formate and 3.5% sodium phosphate.

[0058] Example 5

[0059] Preparation of antifreeze based on sodium formate:

[0060] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, and then 8 parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:0.2.

[0061] Two parts of polycarboxylate superplasticizer were dissolved in 450 parts of MES buffer at pH 5.5, and then 0.15 parts of EDC and 0.15 parts of NHS were added. The mixture was stirred and activated at room temperature for 30 min. Five parts of MOF material were ultrasonically dispersed in 50 parts of MES buffer at pH 5.5 and mixed with the activated polycarboxylate superplasticizer solution. The mixture was reacted at room temperature for 6 h, centrifuged, washed three times with water, and then washed three times with ethanol. The mixture was then vacuum dried at 60 °C for 12 h to obtain the polycarboxylate modified MOF material.

[0062] Five parts of polycarboxylate-modified MOF material were immersed in 400 parts of a 35% sodium formate aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and vacuum dried at 60°C for 12 hours to obtain the antifreeze.

[0063] Comparative Example 1

[0064] Preparation of antifreeze based on sodium formate:

[0065] Five parts of ZrOCl2·8H2O were dissolved in 500 parts of N,N-dimethylformamide, then eight parts of organic ligand and 40 parts of glacial acetic acid were added. After mixing, the mixture was transferred to a high-pressure reactor and reacted at 120°C for 24 h. After centrifugation, the mixture was washed three times with N,N-dimethylformamide and then three times with ethanol. The mixture was then vacuum dried at 80°C for 7 h to obtain the MOF material. The organic ligand was 2-aminoterephthalic acid.

[0066] Five parts of MOF material were immersed in 400 parts of a 35% sodium formate aqueous solution for 30 hours for adsorption. After centrifugation, the material was washed twice with ethanol and dried under vacuum at 60°C for 12 hours to obtain the antifreeze.

[0067] Test section

[0068] The antifreeze agents obtained from each embodiment and comparative example were tested according to GB / T 8076-2008 "Concrete Admixtures". The dosage of the antifreeze agent was 1.5 wt% of the cement content, and its water reduction rate and slump retention rate after 1 hour were tested.

[0069] Referring to JGJ 55-2000 "Specification for Mix Proportioning of Ordinary Concrete", concrete cubes (water-cement ratio of 0.4) with dimensions of 100mm×100mm×100mm were prepared with an antifreeze dosage of 1.5wt% of cement. Following the rapid freezing method in "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", the concrete was cured for 7 days, then placed at -15℃ for 4 hours, and then at 20℃ for 4 hours. This cycle was repeated 100 times, and the mass loss rate was recorded.

[0070] Table 1

[0071] Water reduction rate (%) 1-hour slump retention rate (%) Quality loss rate (%) Example 1 35.6 86.3 1.12 Example 2 34.9 87.6 1.08 Example 3 30.5 79.6 2.26 Example 4 29.5 85.3 1.69 Example 5 31.2 78.3 2.01 Comparative Example 1 18.6 56.8 4.69

[0072] As shown in Table 1, the antifreeze agents obtained in each embodiment have higher water reduction rates, 1-hour slump retention rates, and lower mass loss rates compared to the comparative example, indicating that the antifreeze agents obtained in each embodiment have good water reduction and long-term antifreeze effects. This may be because, in Comparative Example 1, MOF material was directly used to load sodium formate, and the water reduction effect of the released sodium formate alone was poor. In contrast, the polycarboxylate superplasticizer on the MOF surface in each embodiment achieved a better water reduction effect. However, the loaded sodium formate was more easily lost compared to the other embodiments, resulting in poorer slump retention and long-term antifreeze performance.

[0073] As can be seen from Examples 1 to 4, the use of different organic ligands to prepare MOF materials has a certain impact on the water-reducing and antifreeze properties of the antifreeze. When the organic ligands are 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid in a mass ratio of 1:0.2 to 0.5, the antifreeze has better water-reducing and long-lasting antifreeze effects.

[0074] As can be seen from Examples 1 and 5, by loading a small amount of sodium phosphate into the antifreeze, sodium formate can be used in conjunction to give the antifreeze a better water-reducing and long-lasting antifreeze effect.

[0075] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a sodium formate-based antifreeze, characterized in that, Includes the following steps: Step S1: Dissolve zirconium-based metal salt and organic ligand in an organic solvent, and form a framework structure between zirconium ions and organic ligand through a solvothermal reaction to obtain MOF material; wherein, the organic ligand includes at least one of 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid; Step S2: After activating the carboxyl groups on the polycarboxylate superplasticizer, react it with the amino groups on the MOF material to obtain the polycarboxylate modified MOF material; Step S3: Immerse the polycarboxylate-modified MOF material in an aqueous sodium salt solution to allow the sodium salt to be adsorbed and loaded onto the polycarboxylate-modified MOF material, thereby obtaining an antifreeze agent; wherein the sodium salt includes sodium formate.

2. The method according to claim 1, characterized in that, Step S1 specifically includes: Five parts of zirconium-based metal salt, 7-15 parts of organic ligand and 20-50 parts of glacial acetic acid were dissolved in 300-600 parts of N,N-dimethylformamide and reacted in a high-pressure reactor at 115-130°C for 18-30 h to obtain MOF material.

3. The method according to claim 1 or 2, characterized in that, The zirconium-based metal salt includes ZrOCl2·8H2O.

4. The method according to claim 1 or 2, characterized in that, The organic ligands include 2-aminoterephthalic acid and 2,5-diaminoterephthalic acid, wherein the mass ratio of 2-aminoterephthalic acid to 2,5-diaminoterephthalic acid is 1:0.2 to 0.

5.

5. The method according to claim 1, characterized in that, Step S2 specifically includes: Dissolve 1-3 parts of polycarboxylate superplasticizer, 0.1-0.3 parts of EDC and 0.1-0.3 parts of NHS in 300-600 parts of buffer solution with pH 5-6.5, then add 5 parts of MOF material and react for 4-8 hours to obtain polycarboxylate modified MOF material.

6. The method according to claim 1, characterized in that, Step S3 specifically includes: Five parts of polycarboxylate-modified MOF material were immersed in 300-600 parts of sodium salt aqueous solution for 24-36 hours to obtain an antifreeze agent; wherein the sodium salt aqueous solution contained sodium formate at a mass fraction of 20%-40%.

7. The method according to claim 6, characterized in that, The sodium salt aqueous solution also includes sodium phosphate, and the mass fraction of sodium phosphate in the sodium salt aqueous solution is 2% to 5%.

8. An antifreeze based on sodium formate, characterized in that, Prepared according to the method according to any one of claims 1 to 7.

9. A concrete building material, characterized in that, Includes the antifreeze agent as described in claim 8.

10. The concrete building material according to claim 9, characterized in that, The dosage of the antifreeze agent is 0.5% to 2.5% of the cement dosage.