SU33146A1 - The method of obtaining concentrated solutions of lactic acid - Google Patents

Description

The present invention relates to methods for preparing concentrated solutions of lactic acid by treating concentrated solutions of lactic calcium salts with sulfuric acid in the presence of free lactic acid.

The invention consists in the fact that a mixture of a solution or crystals of milk calcium with time is subjected to evaporation (with a solution of lactic acid, after which the resulting solution is processed in the usual way with sulfuric acid and filtered from gypsum by ordinary filtration.

The following methods are known for producing concentrated lactic acid.

The first method is reduced to the evaporation of lactic acid solutions. This method has a number of discharges / of which the main ones are: significant losses of lactic acid during evaporation of its solutions, large formation of lactic anhydrides during evaporation, and a hard to resolve issue.

The second method of obtaining concentrated lactic acid, as described in term, patents No. 221112 and No. 222741 (see Fortschrftte derTeerfarbenfabrikation. Dr. F. Friedlaerider, vol. 10, pp. 85--87),

(186)

The aim is to avoid the shortcomings of the first method just indicated, and that the evaporation is not a solution of lactic acid, but a solution of calcium lactate. Next, one stripped off calcium lactate solution is mixed with concentrated molar acid, and then decomposed with sulfuric acid, or one stripped off calcium calcium lactate solution is decomposed by sulfuric acid, to which concentrated lactic acid has previously been added.

The work on the second method of obtaining concentrated lactic acid from a number of difficulties: 1) after the decomposition of calcium lactate with sulfuric acid, a precipitate of gypsum is obtained (along with lactic acid). This gypsum after lactic acid filters does contain significant quantities of the latter. Washing the resulting gypsum precipitate here is therefore necessary. As a result of washing this sediment, wash water is obtained, containing a relatively small percentage of lactic acid. Concentration of this wash water according to the second method is a long and complex job that is not justified in practice; 2) in order to obtain highly concentrated lactic acid (ooo / o), it is necessary to preserve the mpoflbHcfc method, | It is cracked calcium lactate, which is a matter of profitability of production.

The proposed method of preparing concentrated lactic acid has the aim of eliminating the above mentioned disadvantages of the first and second methods and consists in the fact that lactic acid containing solutions are concentrated in the presence of a lactic acid salt, followed by decomposition with sulfuric acid in the usual way.

Example 1. In a 120 kg solution of varnish, calcium tata, containing 20% CHsCHOHCOOv

Sn Snons; oo. °°

dairy acid supplement with: obsession, UNHELD. The mixture is evaporated to 100 KI, then treated with the required amount of sulfuric acid, filtered from the precipitated gypsum. The filtrate contains approximately 40% lactic acid, ..

Example 2. In 180 KI calcium lactate solution containing 30%

SNS € HONSOO CH.CHOHGOO / °

solution of lactic acid with a content of 40% CHNSOHONS. The mixture is evaporated to 195 kg and then treated with the required amount of sulfuric acid. After filtering out gypsum from the filter, a lactic acid solution is obtained with a content of about.

Pr im € 3. 150 to ASTShera varnish; tata calcium containing 40

SNSNONSOOCH

SNSNONSOOH

solution of lactic acid with a content of 60% CHNSOHONS. The mixture is evaporated to 195 kg and then processed by a three-; / buffered amount of sulfuric acid. After filtration of the precipitated gypsum, a solution of lactic acid is obtained, containing approximately 80% of CH 2 CHONSOL.

The subject matter of the invention.

Claims (2)

1. A method of preparing 5 centric solutions of lactic acid by treating concentrated solutions: a lactic calcium salt with sulfuric acid in the presence of free lactic acid, characterized in that the mixture is concentrated by evaporation to a concentration of sulfuric acid with a dilute lactic acid solution, after which The treatments-i are concentrated; the solution is sulfuric acid in the usual way: and the resulting solution of lactic acid is separated from gypsum by ordinary filtration. 2. With the method according to claim 1 use; wash water from sediment gypsum, pblyJ. according to claim 1, as a weak solution of lactic acid for mixing with calcium lactic acid. According to claim 1.