Preparation method and application of anhydrous citric acid

A technology of anhydrous citric acid and citric acid, applied in the separation/purification of carboxylic acid compounds, organic chemistry, etc., can solve problems such as uneven distribution, affecting taste or utility, increasing production costs, etc., to improve temperature uniformity, Avoid the effect of excessive grain growth and reduce the cooling rate

Inactive Publication Date: 2022-04-12
NINGXIANG XINYANG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, the former is restricted by the size of the seed crystal and its dispersion uniformity, and it is not easy to obtain fine-grained and uniform grains, while the latter is easy to induce crystal aggregation growth and cause the grain distribution to be too wide
[0004] Some fields such as solid additives have high requirements on product particle size and distribution. If the particles are too coarse or unevenly distributed, it will directly affect its taste or effectiveness.
In order to obtain fine-grained anhydrous citric acid, the existing practice is to perform secondary mechanical crushing on the crystallized product, which increases the production cost

Method used

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  • Preparation method and application of anhydrous citric acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] The preparation method of anhydrous citric acid is provided, comprising the following steps:

[0038] (1) Add citric acid into deionized water and heat to 90° C. to prepare a clear solution with a mass fraction of citric acid of 80%.

[0039] (2) Under the action of ultrasound, the clarified solution in step (1) was cooled to 84°C at a uniform speed to reach a state close to saturation, wherein the power of the ultrasound was 200W, the frequency was 20kHz, and the cooling time was 6min.

[0040] (3) Keep the ultrasonic effect unchanged, and carry out gradient cooling to the solution obtained in step (2) under negative pressure conditions; during the cooling process, the pressure is 15kPa; the initial cooling rate is 0.1°C / min, and the temperature drops every 10°C The rate drops by 0.01°C / min, and the temperature drops to 44°C.

[0041] (4) The product obtained in step (3) is centrifuged and dried to obtain anhydrous citric acid.

Embodiment 2

[0043] The preparation method of anhydrous citric acid is provided, comprising the following steps:

[0044] (1) Add citric acid into deionized water and heat to 90° C. to prepare a clear solution with a mass fraction of citric acid of 80%.

[0045] (2) Under the action of ultrasound, the clarified solution in step (1) was cooled to 84°C at a uniform speed to reach a state close to saturation, wherein the power of ultrasound was 300W, the frequency was 30kHz, and the cooling time was 6min.

[0046] (3) Keep the ultrasonic effect unchanged, and carry out gradient cooling to the solution obtained in step (2) under negative pressure conditions; during the cooling process, the pressure is 10kPa; The rate drops by 0.006°C / min, and the temperature drops to 44°C.

[0047] (4) The product obtained in step (3) is centrifuged and dried to obtain anhydrous citric acid.

Embodiment 3

[0049] The preparation method of anhydrous citric acid is provided, comprising the following steps:

[0050] (1) Add citric acid into deionized water and heat to 90° C. to prepare a clear solution with a mass fraction of citric acid of 80%.

[0051] (2) Under the action of ultrasound, the clarified solution in step (1) was cooled to 84°C at a uniform speed to reach a state close to saturation, wherein the power of ultrasound was 400W, the frequency was 20kHz, and the cooling time was 6min.

[0052] (3) Keep the ultrasonic effect unchanged, and carry out gradient cooling to the solution obtained in step (2) under negative pressure conditions; during the cooling process, the pressure is 15kPa; the initial cooling rate is 0.1°C / min, and the temperature drops every 10°C The rate drops by 0.01°C / min, and the temperature drops to 44°C.

[0053] (4) The product obtained in step (3) is centrifuged and dried to obtain anhydrous citric acid.

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Abstract

The invention provides a preparation method and application of anhydrous citric acid, and relates to the technical field of organic acids. The method comprises the following steps: cooling an unsaturated solution of citric acid to a saturated state under the ultrasonic action; the ultrasonic action is kept unchanged, and cooling crystallization is performed at the speed of 0.05-0.2 DEG C / min; and carrying out solid-liquid separation, and drying the solid phase. The method can be used for preparing crystal grains with finer granularity and more uniform granularity, improving the quality of the anhydrous citric acid and overcoming the defect that the granularity and distribution of the product are difficult to control in the existing crystallization method.

Description

technical field [0001] The invention relates to the technical field of organic acids, in particular to a preparation method and application of anhydrous citric acid. Background technique [0002] Citric acid is a kind of organic acid, which is often used as an additive in food, pharmaceutical, chemical and other fields. Citric acid usually exists in the form of anhydrate or monohydrate. Crystallization in cold water mainly produces monohydrate, and crystallization in hot water (critical temperature 36.6°C) produces anhydrate. Compared with citric acid monohydrate, anhydrous citric acid is more suitable for use as an additive in foods such as solid beverages because it does not contain crystal water. [0003] The existing crystallization methods of anhydrous citric acid mainly include adding seed crystals and evaporative crystallization. Among them, the former is restricted by the size of the seed crystal and its dispersion uniformity, and it is not easy to obtain fine-grai...

Claims

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Application Information

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IPC IPC(8): C07C51/42C07C51/43C07C59/265
Inventor 石志勇
Owner NINGXIANG XINYANG CHEM
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