RU1775392C - Sorbic acid cleaning method - Google Patents

Abstract

Usage: as an intermediate in the chemical industry. SUMMARY OF THE INVENTION: mixing sorbic acid CH3CH = CH-CH = CH-COOH, BF SbHbOa with water at a weight ratio of 1: 0.89-0.92 at 13-15 ° C, followed by filtration at the same temperature. 1 tab.

Description

The present invention relates to methods for purifying substances and can be used in the chemical industry.

A known method for producing pure sorbic acid with a desired particle size spectrum, comprising mixing sorbic acid with water, heating the suspension to 150 ° C under elevated pressure, then cooling the suspension with stirring, followed by evaporation of crystals of purer sorbic acid.

The disadvantages of this method include significant energy consumption, and the need to work at elevated temperatures (105-150 ° C) and pressures far above atmospheric.

These disadvantages are eliminated in the method of purification of sorbic acid used on TPO Pigment.

A known method of purification of sorbic acid, according to which through a fixed layer of sorbic acid paste (SC), filtered from a cooled mother liquor, water is passed at a temperature of 410 ° C in an amount of 6.5 kg of water per 1 kg of dry SC. At the same time, approximately 1% of the initial dry CK mixture is removed with wash water.

The main disadvantage of this cleaning method is the significant consumption of washing water.

This drawback is caused by the presence of a fixed layer of crystals, in which the supplied water rinses the channels, the impurity solution and part of sorbic acid, and passes through them, passing other areas with high resistance. In this case, non-washed stagnant zones remain, having a high content of unremoved impurities, an increased amount of washing water is consumed, losses of sorbic acid with washing water increase, and the performance of the filtering apparatus decreases.

Rinsing water containing impurities removed from the layer and some amount of dissolved sorbic acid requires obligatory subsequent purification.

The aim of the invention is to reduce the water consumption for washing sorbic acid.

This goal is achieved by the fact that sorbic acid is mixed with water at a mass ratio of 1: (0.89-0.92), and mixing and filtration is carried out at a temperature of 13-15 ° C.

For the most complete removal of soluble impurities from the surface of the particles with a minimum flow rate of wash water, the following must be performed.

Ensure that the entire surface of the particles is wetted with water, which is done if the volume of the wash water (VnpOM.) Is larger or the free pore volume of the dry sorbic acid layer (Vnop drySK) is injured

VnpOM, Vnop dry SC,

Remove contact between particles of sorbic acid, which is accomplished by mixing sorbic acid with water if VnpoMi Vnop is dry.

The solvent of the impurity in water, which is possible if the concentration of impurities in the wash water (Ex.) Is less than the concentration of the saturated solution (,), i.e. (Ex.

Remove by filtration wash water containing dissolved impurities.

To prevent losses of sorbic acid with wash water of more than 1% of its initial mass, which corresponds to losses of sorption acid when it is washed by a known method. The amount of loss of sorbic acid due to its dissolution in the wash water depends on the flow rate and temperature of the wash water.

The following has been experimentally established:

most of the soluble impurities in water are located on the surface of sorbic acid crystals;

said impurities are much more soluble in water than sorbic acid.

This makes it possible to drastically reduce the volume of water supplied to the mixture for purification of sorbic acid according to the proposed method.

The lowest bulk density of dry sorbic acid in various batches is 600-610 kg / m, and the free pore volume of dry sorbic acid is 0.8360, 809 l / kg, respectively.

To ensure complete wetting of the particles of sorbic acid, dry throughout the layer at the beginning of mixing, we have accepted and experimentally confirmed that the mass of water supplied to the mixing should be 1.1 times larger than the free pore volume, i.e. the mass of water supplied to the mixing is 0.920, 89 kg of water per 1 kg of dry sorbic acid. It has been experimentally confirmed that with this ratio, a mobile homogeneous mixture of sorbic acid with water is rapidly obtained. Necessary

0 to note that, as a result of mixing sorbic acid with water, the free pore volume of the wet mixture decreases to 0.51-0.50 l / kg, respectively.

With a large array ratio

5 sorbic acid to water, obtaining by mixing a homogeneous moving mass will be difficult, which will lead to incomplete removal of impurities from the surface of the particles. As shown by us

0 experiments, with a lower mass ratio of sorbic acid to water, the quality of the washed sorbic acid is not significantly improved, and the flow rate and loss of sorbic acid with filtrate

5 increase.

The temperature limits for purification of sorbic acid by the proposed method, equal to 13-15 ° C, were found experimentally. The results of experimental verification of the proposed method are presented in examples 1 and 2, in which the melting point of the starting and purified sorbic acid is equal to the average of 3 determinations.

5 The invention is illustrated by the following examples.

An example implementation of the proposed method (see, examples 1-2, table).

100 g dry crude sorbic

0 acids were charged into a 500 ml flask, 89-92 ml of water was added, cooled to a temperature of 15-13 ° C, respectively, and stirred until a homogeneous mass was obtained. The resulting mixture was filtered through filter paper on a Buchner funnel in vacuo. The purified sorbic acid was dried under vacuum at a temperature of 60 ° C and the melting point was determined (at least 3 samples). Measured

0 filter volume, its temperature. Titration with an aqueous NaOH solution in the presence of phenolphthalein determined the total acid content in the filtrate. Using the curve we received earlier

Claims (1)

5 of the solubility of sorbic acid in water, the concentration of sorbic acid and its mass in the filtrate were found at the temperature of the filtrate. The mass of dissolved substances in the filtrate was found by drying to a constant mass under vacuum at 60 ° С 25 ml of the filtrate, followed by o, for the entire volume of the filtrate. The mass of soluble impurities removed with the filtrate was found by subtracting the mass of sorbic acid in the filtrate from the mass of substances dissolved in the filtrate. According to the described method, experiments were also carried out on the purification of sorbic acid by the proposed method at the limiting values of the temperature and the mass of water supplied for mixing (see, examples 3-8, table). From examples 1 and 2 it is seen that when cleaning the source of sorbic acid according to the proposed method, within the characteristics indicated in the distinguishing part (water consumption and temperature of the mixture), the amount of the removed mixture does not exceed 1% of the mass of the original sorbic acid, and the melting temperature increases from 130, 1 for crude sorbic acid up to 130.83130, 88 ° C for purified sorbic acid. From example 3 it is seen that as a result of purification at a temperature exceeding that indicated in the distinctive part and a consumption of water for mixing lower than that indicated in the distinctive part, the quality of purification decreases and the average temperature of the purified sorbic acid is 130.70 ° C. In addition the amount of sorbic acid removed with the filtrate increases (loss of SC). Example 4 shows that, as a result of purification at a temperature lower than that indicated in the distinctive part and the flow rate of water for mixing in excess of the flow rate, In the distinguishing part, the quality of the cleaning is reduced and the average melting point of the purified sorbic acid is 130.78 ° C. From the examples given in the table, it can be seen that when cleaning is carried out at a temperature and water consumption for mixing, different from the values indicated in the distinctive part , losses of SC with the filtrate increase with a simultaneous deterioration in the quality of treatment (see examples 3, 57), water consumption increases with a simultaneous deterioration in quality (see Example 4), deterioration in the quality of purification (see Examples 6, 8). To compare the proposed and known method for purification of sorbic acid, laboratory purification of sorbic acid was carried out according to a known method. For this, 100 g of crude dry sorbic acid was placed on a filter paper layer in a 100 mm Buchner funnel. 0.65 L of water was fed into the funnel at a temperature of 7 ° C, which was passed from top to bottom through a fixed layer of sorbic acid. The volume of the filtrate, its temperature, and the total content of acidic substances were measured. The washed sorbic acid was dried under vacuum at C and then its melting point was determined. The results are presented below. The results of the purification of sorbic acid by a known method. 100 g of dry sorbic acid was charged to purify. Served for washing 650 g of water. The temperature of the wash water was 7 C. 1.120 g of dissolved substances, including 0.275 g of sorbic acid, were removed with the filtrate. The melting point of sorbic acid before purification is 130.1 ° C. The melting point of sorbic acid after purification is 130.73 ° C. Comparison of experimental results. A thorough check of the proposed method (examples 1 and 2, table) and the known method shows the following: purification of sorbic acid by the proposed method allows to obtain sorbic acid of a higher degree of purification. Thus, the melting point of sorbic acid purified by the proposed method is 130.83-130.88 ° C and by the known method 130.73 ° C; loss of sorbic acid with filtrate during purification by the proposed method is 0.375-0.378 g per 21 kg of the original sorbic acid, and by the known method 2.75 g per 1 kg of the original sorbic acid, i.e., the loss of sorbic acid by the proposed method, about; 7 times less than the known; water consumption, when cleaning sorbic acid according to the proposed method is 0.89-0.92 kg per 1 kg of dry sorbic acid, and according to the known method is 6.5 kg per 1 kg of dry sorbic acid, t, e, water consumption by the proposed method is 7.1-7.3 times less than the known one. The above results allow us to conclude that the proposed method is more economical and efficient. SUMMARY OF THE INVENTION A method for purifying sorbic acid by treating it with water, followed by filtration, characterized in that, in order to reduce water consumption, sorbic acid is mixed with water when they are The results of the purification of sorbic acid by the proposed method at the extreme and transcendent values of the temperature and volume of water supplied mass ratio of 1: 0.89-0.92. moreover, mixing and filtering is carried out at 1315 ° C.