Sodium gluconate for concrete admixture as well as preparation method and application of sodium gluconate

Abstract

According to the sodium gluconate for the concrete admixture and the preparation method and application of the sodium gluconate, glucose serves as a raw material, water serves as a solvent, hydrogen peroxide serves as an oxidizing agent, ferrous sulfate serves as a catalyst, glucose is catalytically oxidized and converted into sodium gluconate under the normal-temperature state through low-frequency ultrasonic excitation, the reaction time is short, and the yield is high. And the conversion rate of glucose can reach 97% or above. Compared with the prior art, the method has the advantages of mild reaction conditions, high product conversion rate, high glucose conversion rate and no redundant by-product. Meanwhile, compared with commercially available sodium gluconate, the preparation method has the advantages that the use cost of the sodium gluconate can be saved by 600-1000 yuan / ton, and the synthesized sodium gluconate is in a solution state, can be used without being further dissolved and has a relatively high practical value in the concrete admixture industry.

Description

Technical Field

[0001] The invention belongs to the field of material preparation, and particularly relates to sodium gluconate for concrete admixture and a preparation method and application thereof. Background Art

[0002] Concrete admixtures are an indispensable item in the concrete production process. In order to meet various requirements of concrete, such as collapse resistance, setting time, frost resistance, etc., it is often necessary to add other auxiliary materials besides polycarboxylic acid water reducer to the concrete admixture to meet the requirements. Sodium gluconate is one of such auxiliary materials.

[0003] The main function of sodium gluconate in concrete water reducer is to inhibit the hydration reaction of cement to prolong the setting time of concrete, so that concrete can maintain plasticity for a longer time, ensure that concrete has good workability during construction, and improve construction efficiency. In addition, the addition of sodium gluconate has no adverse effects on various later indicators of concrete. Sodium gluconate has now become the largest and most widely used concrete admixture auxiliary material in the concrete admixture industry.

[0004] At present, the chemical method for preparing sodium gluconate is divided into homogeneous chemical oxidation method, heterogeneous chemical oxidation method and electrolytic oxidation method. The production process of electrolytic oxidation method consumes a lot of energy and the conditions are difficult to control; the heterogeneous chemical oxidation method generally requires precious metals for catalysis, and oxygen needs to be passed during the reaction process, and the conditions are also difficult to control; the homogeneous chemical oxidation method is not only low in cost and simple to operate, but also because the concrete admixture has low requirements for sodium gluconate, the sodium gluconate solution synthesized by the homogeneous chemical oxidation method does not need further separation and purification, and can be used directly, which further saves the cost of sodium gluconate synthesis.

[0005] Although sodium gluconate has advantages such as good retarding effect, its price is relatively high. Taking Anhui Conch New Material Technology Co., Ltd. as an example, the annual purchase volume of sodium gluconate is more than 5,000 tons, and the average purchase price is 4,387 yuan / ton. If the price of sodium gluconate can be reduced by 400-1,000 yuan / ton, the cost can be saved by 2-5 million yuan, which can bring great economic value. In addition, the purchased sodium gluconate needs to be dissolved in advance.

[0006] Therefore, it is very necessary to provide a method for preparing sodium gluconate with low cost. Summary of the invention

[0007] The purpose of the present invention is to provide sodium gluconate for concrete admixture and a preparation method thereof, wherein glucose is used as a raw material, water is used as a solvent, hydrogen peroxide is used as an oxidant, and ferrous sulfate is used as a catalyst, and glucose is catalytically oxidized at room temperature by low-frequency ultrasonic excitation to be converted into sodium gluconate, the reaction time is short, and the conversion rate of glucose can reach more than 97%, thereby solving the problem that sodium gluconate for concrete admixture is high in price and needs to be dissolved in advance.

[0008] Another object of the present invention is to provide an application of sodium gluconate for concrete admixture, which is used for concrete preparation. The sodium gluconate obtained by the present invention is in a solution state and can be used without further dissolution, and has high practical value in the concrete admixture industry.

[0009] The specific technical solutions of the present invention are as follows:

[0010] A method for preparing sodium gluconate for concrete admixture, specifically comprising:

[0011] Glucose is dissolved in water, and then a catalyst is added. Under low-frequency ultrasonic conditions, an oxidant is added dropwise thereto. After the reaction, the mixture is neutralized to obtain sodium gluconate for concrete admixture.

[0012] The mass ratio of glucose to water is 0.8-1:1;

[0013] The mass ratio of glucose to catalyst is 300-350:1;

[0014] The catalyst is ferrous sulfate;

[0015] The mass ratio of glucose to oxidant is 1:1-1.5;

[0016] The oxidant is hydrogen peroxide with a mass concentration of 30%;

[0017] The adding of oxidant dropwise refers to adding the oxidant dropwise;

[0018] The low-frequency ultrasound has an ultrasound frequency of 25KHz;

[0019] The reaction refers to a reaction time of 0.8-1.2h under 25KHz low-frequency ultrasound conditions;

[0020] The reaction is carried out at room temperature;

[0021] The neutralization refers to adding liquid caustic soda for neutralization, and the mass concentration of the liquid caustic soda is 30%.

[0022] Preferably, the preparation method of sodium gluconate for concrete admixture provided by the present invention is:

[0023] According to the mass percentage, 180 parts of glucose were dissolved in 205 parts of water, and then 0.54 parts of ferrous sulfate catalyst was added after the dissolution. Then, 25KHz low-frequency ultrasound was turned on and 227 parts of hydrogen peroxide were dripped drop by drop. After the addition was completed, the reaction was continued for one hour, and finally 130 parts of liquid alkali was added for neutralization to obtain a sodium gluconate solution with a mass content of 40%.

[0024] The invention provides sodium gluconate for concrete admixture, which is prepared by adopting the above preparation method.

[0025] The application of sodium gluconate for concrete admixture provided by the present invention is used for concrete preparation, and the sodium gluconate is directly used as a retarder for concrete preparation without the need for additional dissolution or configuration.

[0026] The preparation method of sodium gluconate for concrete admixture of the present invention mainly comprises the following reaction processes:

[0027] Fe 2+ +H2O2→Fe 3+ +OH - +HO (1)

[0028] Fe 3+ +H2O2→Fe 2+ +H + +HO2 (2)

[0029] Fe 3+ +HO2·→Fe 2+ +O2+H + (3)

[0030] It can be seen from the above reaction equation that H2O2 will generate hydroxyl radicals with strong oxidizing ability through the Fenton reaction in the presence of ferrous ions, and the effect of ultrasound can not only stimulate the occurrence of the Fenton reaction and make the hydroxyl radicals more evenly present in the solution, but also enable glucose to react with hydroxyl radicals more fully.

[0031] According to the latest market price of raw materials, the cost price of preparing one ton of sodium gluconate with a content of 40% using the present invention is 1,430 yuan, while the price of commercially available sodium gluconate calculated at a concentration of 40% is 1,750 yuan. The present invention can reduce the cost by 320 yuan / ton, which can be reduced by 800 yuan / ton when converted into solid.

[0032] Compared with the prior art, the present invention provides a preparation method for synthesizing sodium gluconate from glucose by catalyzing glucose in one pot under the action of low-frequency ultrasound, with mild reaction conditions and high product conversion rate, with a glucose conversion rate of more than 97% and up to 99%, and a sodium gluconate yield of 98%. There are no unnecessary by-products. At the same time, compared with commercially available sodium gluconate, the preparation method of the present invention can save the use cost of sodium gluconate by 600-1000 yuan / ton, and the synthesized sodium gluconate is in a solution state and can be used without further dissolution, which has high practical value in the concrete admixture industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the infrared spectrum of the product of Example 1. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0036] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0037] Example 1

[0038] A preparation method of sodium gluconate for concrete admixture is:

[0039] According to the mass fraction, 180 parts of glucose were dissolved in 205 parts of water, and then 0.54 parts of ferrous sulfate catalyst was added after the dissolution. At room temperature, low-frequency ultrasound at a frequency of 25KHz was then turned on, and 227 parts of 30% hydrogen peroxide solution was dripped dropwise. After the addition was completed, the reaction was continued for one hour, and finally 130 parts of liquid alkali was added for neutralization to obtain a sodium gluconate solution with a mass content of 40%. The infrared spectrum of the product is shown in FIG. Figure 1 shown.

[0040] Comparative Example 1

[0041] A preparation method of sodium gluconate for concrete admixture is:

[0042] In parts by mass: 180 parts of glucose are dissolved in 205 parts of water, and then 0.54 parts of ferrous sulfate as a catalyst are added after dissolution. At room temperature, 227 parts of 30% hydrogen peroxide are added dropwise. After the addition is completed, the reaction is continued for one hour. Finally, 130 parts of liquid alkali are added for neutralization to obtain a sodium gluconate solution.

[0043] In order to verify the necessity of ultrasonic excitation, the present invention compares the conversion rate of sodium gluconate synthesized by the method described in Comparative Example 1 without ultrasonic excitation and that by using ultrasonic excitation in Example 1. The conversion rate is calculated by high performance liquid chromatography on the residual amount of product glucose. The test results are shown in Table 1.

[0044] Table 1 Comparison of preparation results of Example 1 and Comparative Example 1

[0045] type Test conditions Glucose conversion rate Sodium gluconate yield Comparative Example 1 blank 20％ 15％ Example 1 Low frequency ultrasound excitation 99％ 98％

[0046] It can be seen from Table 1 above that, without ultrasonic excitation, the glucose conversion rate is only 20%, and the yield of sodium gluconate is only 15%. However, the yield of sodium gluconate synthesized under ultrasonic excitation using Example 1 of the method of the present invention reaches 98%, which shows that ultrasonic excitation is a necessary condition for sufficient reaction.

[0047] The performance of the sodium gluconate synthesized under ultrasonic excitation was tested in accordance with the "Test Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency" (GB / T 1346-2011). The effect of sodium gluconate on the setting time of cement was tested. The dosage was 0.2%. The test results are shown in Table 2 below.

[0048] Table 2 Results of using different sodium gluconates in cement

[0049]

[0050]

[0051] It can be seen from the results in the above table that the initial setting and final setting times of cement made of commercially available sodium gluconate are consistent with those in the examples, indicating that the retarding properties of the sodium gluconate synthesized in the present invention are consistent with those of commercially available sodium gluconate, and the sodium gluconate synthesis method of the present invention can synthesize sodium gluconate with a higher conversion rate.

[0052] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing sodium gluconate for concrete admixture, characterized in that: The preparation method is specifically: Dissolve glucose in water, add a catalyst, and then drop an oxidant into the water under low-frequency ultrasonic conditions. After the reaction, neutralize the water to obtain the product.

2. The preparation method according to claim 1, characterized in that: The mass ratio of glucose to water is 0.8-1:

1.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the glucose to the catalyst is 300-350:

1.

4. The preparation method according to claim 1 or 3, characterized in that: The catalyst is ferrous sulfate.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the glucose to the oxidant is 1:1-1.

5.

6. The preparation method according to claim 1 or 5, characterized in that: The oxidant is hydrogen peroxide with a mass concentration of 30%.

7. The preparation method according to claim 1, characterized in that: The low-frequency ultrasound refers to 25KHz; the reaction refers to a reaction time of 0.8-1.2h under low-frequency ultrasound conditions.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: dissolving 180 parts of glucose in 205 parts of water by mass, adding 0.54 parts of ferrous sulfate as a catalyst after the glucose is dissolved, then starting 25KHz low-frequency ultrasound, dripping 227 parts of hydrogen peroxide drop by drop, continuing the reaction for one hour after the dripping is completed, and finally adding 130 parts of liquid alkali for neutralization, so as to obtain a sodium gluconate solution with a mass content of 40%.

9. Sodium gluconate for concrete admixture prepared by the preparation method according to any one of claims 1 to 8.

10. An application of sodium gluconate for concrete admixture according to claim 9, characterized in that: Used in concrete preparation.

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