阅读说明：本技术 利用硫氨酯尾液制备巯基乙酸钠临界饱和水溶液的方法 (Method for preparing critical saturated aqueous solution of sodium thioglycolate by utilizing thiourethane tail liquid ) 是由 王丽艳 李芳� 沈文斌 于 2020-07-24 设计创作，主要内容包括：一种利用硫氨酯尾液制备巯基乙酸钠临界饱和水溶液的方法,首先对生硫氨酯的尾液用无机酸酸化处理,得到酸化液,pH=0.5-2；将酸化液静置,分离为上层有机层和下层酸化层；酸化层加入有机溶剂进行萃取；萃取液加入氢氧化钠溶液进行反应,回收有机溶剂后得到巯基乙酸钠临界饱和水溶液。本发明利用硫氨酯尾液制备巯基乙酸钠临界饱和水溶液,该饱和液能够直接进行使用,避免了巯基乙酸钠固体产品生产耗能量大、且易潮不稳定的特性；制备得到的巯基乙酸钠临界饱和水溶液纯度较高,不含其他杂质,尤其是不含有硫氨酯。(A method for preparing critical saturated aqueous solution of sodium thioglycolate by utilizing tail liquid of thionocarbamate comprises the following steps of firstly, carrying out acidification treatment on the tail liquid of the thionocarbamate by using inorganic acid to obtain acidified liquid, wherein the pH is = 0.5-2; standing the acidizing fluid, and separating into an upper organic layer and a lower acidizing layer; adding an organic solvent into the acidification layer for extraction; adding sodium hydroxide solution into the extract liquor for reaction, and recovering the organic solvent to obtain the critical saturated aqueous solution of sodium thioglycolate. The invention utilizes the thiourethane tail liquid to prepare the critical saturated aqueous solution of sodium thioglycolate, and the saturated solution can be directly used, thereby avoiding the characteristics of high energy consumption and unstable moisture tendency of the production of the solid product of sodium thioglycolate; the prepared sodium thioglycolate critical saturated aqueous solution has high purity, does not contain other impurities, and particularly does not contain thiourethane.)

1. A method for preparing a critical saturated aqueous solution of sodium thioglycolate by utilizing a thiourethane tail solution is characterized by comprising the following steps of:

(1) acidifying tail liquor for producing O-alkyl-N-alkyl thionocarbamate with inorganic acid to obtain acidified liquor with pH = 0.5-2;

(2) standing the acidizing fluid, and separating into an upper organic layer and a lower acidizing layer;

(3) adding an organic solvent into the acidification layer in the step (2) for extraction;

(4) and (4) adding the extract liquor obtained in the step (3) into a sodium hydroxide solution for reaction, and recovering the organic solvent to obtain a critical saturated aqueous solution of sodium thioglycolate.

2. The method of claim 1, further comprising the step (5): and (3) adding a sodium hydroxide solution into the organic layer obtained in the step (2) for reaction, and recovering the organic solvent to obtain a sodium thioglycolate critical saturated solution.

3. The method of claim 1, wherein the acidification layer in the step (2) is filtered and decolored by activated carbon and removes particulate impurities.

4. The method of claim 1, wherein after the acidification and standing for 24-52h in step (2), the distinct organic layer is first separated, and then the organic layer and the acidified layer are thoroughly separated by using one of a carbon fiber column, a coalescing filter element, an ultrafiltration ceramic membrane, and the like; or, after the acidification and standing for 24-52h in the step (2), firstly separating an obvious organic layer, then completely separating the organic layer and the acidification layer by using a high-speed centrifugation method, and removing thiourethane in the acidification layer; or after the acidification and standing for 24-52h in the step (2), firstly separating an obvious organic layer, then adding isopropyl ether with the volume of 2-4% of that of the acidification liquid, fully and uniformly mixing to dissolve organic matters such as thiourethane and the like in the isopropyl ether, then completely separating the organic layer and the acidification layer by using a high-speed centrifugation method, and removing the thiourethane from the acidification layer.

5. The method according to claim 1, wherein the organic solvent added for extraction in the step (3) is one or more of acetone, ethyl acetate, 1-dichloroethane, butyl ether, isobutyl acetate, isopropyl ether, propyl acetate, 1, 2-dichloroethane, and petroleum ether; the volume ratio of the added organic solvent to the acidification layer is 1: 2-4.

6. The method according to claim 5, wherein the organic solvent is a mixed solvent of isobutyl acetate and isopropyl ether, and the volume ratio is 1:1 or 2: 1; or the organic solvent is a mixed solvent of propyl acetate and petroleum ether, and the volume ratio is 2: 1; or the organic solvent is a mixed solvent of 1, 1-dichloroethane and butyl ether, and the volume ratio is 1: 2.

7. the method of claim 1, wherein the concentration of the sodium hydroxide solution in the step (4) is 50%, the adding amount is 25-30wt%, and 30-40wt% of water is continuously added, and the whole reaction process is under the vacuum condition of-0.08 to-0.98 MPa, the reaction continuously generates heat, and the organic solvent in the reaction solution is continuously distilled out and recycled under the reduced pressure condition.

8. The method of claim 1, wherein the sodium hydroxide solution in step (5) has a concentration of 50% and is added in an amount of 2 to 8wt%, and further 4 to 12wt% of water is continuously added, after the reaction is carried out for separation, the aqueous layer and the organic layer are separated, the organic solvent in the aqueous layer is further separated, and the organic layer is recycled.

9. The method of claim 1, wherein said critically saturated aqueous solution of sodium thioglycolate has a concentration of 40 to 45%.

Technical Field

The invention belongs to the technical field of chemical engineering environmental protection, and particularly relates to a method for preparing sodium thioglycolate critical saturated liquid by utilizing thiourethane tail liquid.

Background

Sodium thioglycolate (Sodium thioglycollate), also known as Sodium thioglycolate. Is an organic metal salt. CAS number 367-51-1. In the copper-molybdenum ore flotation, because two polar groups exist in the molecular structure of sodium thioglycolate, sulfydryl and the two minerals are chemically reacted and adsorbed on the surfaces of the minerals, and carboxyl exists in the small molecules and cannot show the collecting performance, but can show hydrophilicity to form a water film, sodium cyanide and sodium hydrosulfide are replaced to be used as inhibitors of copper minerals and pyrite, the sodium thioglycolate flotation agent has the characteristics of small using amount, no toxicity, no pollution, high efficiency and the like, the operating environment and the ecological environment of a mining area of workers can be improved, and the application effect of high-content sodium thioglycolate cannot be achieved by low-content sodium thioglycolate with equimolar amount. The high-purity sodium thioglycolate is also used as an analytical reagent or a chemical cold-ironing liquid for preparation, can be used as an additive in the rubber industry, and can also be used as a fur remover. The high-purity sodium thioglycolate produced by foreign enterprises is mainly applied to the industries of medical intermediates, PVC heat stabilizers, cosmetics and the like.

At present, four production processes of sodium thioglycolate products produced by enterprises at home and abroad are mainly used, wherein firstly, sodium chloroacetate reacts with sodium hydrosulfide to generate sodium thioglycolate; secondly, sodium thiosulfate reacts with chloroacetic acid to prepare thioglycolic acid (a sea wave method), and then sodium thioglycolate is prepared by adding alkali for neutralization; thirdly, preparing sodium thioglycolate by a thiourea method; fourthly, preparing the thiourethane by a monochloroacetic acid esterification method, wherein a byproduct after the preparation, which is often called tail liquid, is directly used as a sodium thioglycolate product. The content of sodium thioglycolate which is not treated is uneven, which causes disorder in the market of sodium thioglycolate and has poor use effect.

Patent No. CN 11056621 provides a method for utilizing a byproduct, namely 2-sodium thioglycolate in the production process of thionocarbamate, 2-sodium thioglycolate is used as a raw material to prepare alkyl thioether carboxylic acid, and the alkyl thioether carboxylic acid is hydroximized to obtain novel alkyl thioether ethyl hydroximic acid, wherein the novel alkyl thioether ethyl hydroximic acid has excellent collecting and extracting capabilities in the flotation of oxidized ores of nonferrous metals.

CN110878037 is a method for high-value utilization of tail liquid in thiourethane production, comprising the steps of extracting and enriching thioglycolic acid in the tail liquid by an extracting agent, reacting to obtain sodium thioglycolate solid, separating out, then acidifying, and extracting to finally obtain a thioglycolic acid product with the purity of more than 99.99%.

The patent No. ZL01131727.2, a method for recovering sodium thioglycolate from waste liquid generated in the production of thionocarbamate, which comprises the steps of extracting the waste liquid containing the sodium thioglycolate with diethyl ether, alkalifying and filtering the extracted waste liquid to obtain a finished product of the sodium thioglycolate.

The above patents all recycle the thiourethane waste liquid, and a new collecting agent is obtained by hydroximizing to obtain a novel alkyl thioether-based ethyl hydroximic acid, but the novel collecting agent performs halogenation and esterification reactions in the waste liquid treatment process, and finally the generated waste liquid is more difficult to treat; 99.99 percent of thioglycollic acid product is obtained by tail liquid purification, although the purity of the finally obtained recovered product is extremely high, a large amount of organic solvent waste liquid is generated in the whole process, and the method is more suitable for being used in a laboratory; the waste liquid after the ether extraction is alkalized twice, quicklime is used for alkalization for the first time in the patent, a large amount of calcium thioglycolate can be generated, the recovery efficiency of the sodium thioglycolate is influenced, in addition, the ether is used, the ether can cause great damage to operating personnel, the recovery rate can be greatly reduced, a large amount of intermediate waste liquid can be generated, and the sodium thioglycolate recovered in the actual use of the method is low in efficiency and contains a large amount of impurities.

Disclosure of Invention

The invention aims to provide a method for preparing a critical saturated aqueous solution of sodium thioglycolate by utilizing a thiourethane tail solution, so as to make up for the defects of the prior art.

In order to achieve the purpose, the invention adopts the following specific technical scheme:

a method for preparing a critical saturated aqueous solution of sodium thioglycolate by utilizing a thiourethane tail solution comprises the following steps:

(1) acidifying tail liquor for producing O-alkyl-N-alkyl thionocarbamate with inorganic acid to obtain acidified liquor with pH = 0.5-2;

(2) standing the acidizing fluid, and separating into an upper organic layer and a lower acidizing layer;

(3) adding an organic solvent into the acidification layer in the step (2) for extraction;

(4) and (4) adding the extract liquor obtained in the step (3) into a sodium hydroxide solution for reaction, and recovering the organic solvent to obtain a critical saturated aqueous solution of sodium thioglycolate.

In order to further improve the recovery rate, the method also comprises the step (5): and (3) adding a sodium hydroxide solution into the organic layer obtained in the step (2) for reaction, and recovering the organic solvent to obtain a critical saturated aqueous solution of sodium thioglycolate.

Further, the inorganic acid in the step (1) is dilute hydrochloric acid with the concentration of 31%.

Further, in the step (2), the acidification layer is filtered and decolored by using activated carbon and granular impurities are removed.

Further, after the acidification and standing are carried out for 24-52h in the step (2), firstly, an obvious organic layer is separated, then, one of a carbon fiber column, a coalescing filter element, an ultrafiltration ceramic membrane and the like is utilized to completely separate the organic layer from the acidification layer, particularly, thiourethane is separated from the acidification layer, and the thiourethane and sodium thioglycolate have opposite characteristics in mining application, so that the prepared critical saturated aqueous solution of sodium thioglycolate is prevented from containing thiourethane.

Or, after the acidification and standing for 24-52h in the step (2), firstly separating an obvious organic layer, then completely separating the organic layer and the acidification layer by using a high-speed centrifugation method, and removing the thiourethane in the acidification layer.

And (3) after the acidification and standing are carried out for 24-52 hours in the step (2), firstly separating an obvious organic layer, then adding isopropyl ether with the volume of 2-4% of that of the acidification liquid, fully and uniformly mixing to dissolve organic matters such as thiourethane and the like in the isopropyl ether, and then completely separating the organic layer and the acidification layer by using a high-speed centrifugation method to remove the thiourethane from the acidification layer.

Further, the organic solvent added and extracted in the step (3) is one or a mixture of acetone, ethyl acetate, 1-dichloroethane, butyl ether, isobutyl acetate, isopropyl ether, propyl acetate, 1, 2-dichloroethane and petroleum ether; the volume ratio of the added organic solvent to the acidification layer is 1: 2-4.

Furthermore, the organic solvent is a mixed solvent of isobutyl acetate and isopropyl ether (the volume ratio is 1:1 or 2: 1).

Or the organic solvent is a mixed solvent of propyl acetate and petroleum ether (the volume ratio is 2: 1).

Or the organic solvent is a mixed solvent of 1, 1-dichloroethane and butyl ether (volume ratio is 1: 2).

Or the organic solvent is a mixed solvent of 1,2 dichloroethane and butyl ether (the volume ratio is 1:1 or 2: 1).

Or the organic solvent is a mixed solvent of acetone and ethyl acetate (the volume ratio is 1: 1).

The solvent proportion is only a part of the list, and the experimental effect is better, and other component proportions can achieve the corresponding extraction effect.

Further, the concentration of the sodium hydroxide solution in the step (4) is 50%, the adding amount is 25-30wt%, and 30-40wt% of water is continuously added, the whole reaction process is under the vacuum condition of-0.08 to-0.98 MPa, heat is continuously generated in the reaction, and the organic solvent in the reaction solution is continuously distilled out and recycled under the reduced pressure condition.

Further, in the step (5), the concentration of the sodium hydroxide solution is 50%, the adding amount is 2-8wt%, and additionally, 4-12wt% of water is continuously added, after reaction layering, a water layer is separated from an organic layer, then, the organic solvent of the water layer is further separated, and the organic layer is recycled.

Furthermore, a small amount of dimercaprol is added in the steps (4) and (5), and the specific examples can show that the recovery rate of sodium thioglycolate is improved.

Further, the concentration of the critical saturated aqueous solution of sodium thioglycolate is 39.5-45%.

Further, the concentration of the critical saturated aqueous solution of sodium thioglycolate is 40%, 40.5%, or 41.5%, or 42%, or 42.5%, or 43%, or 43.5%, or 44%, or 44.5%.

The invention has the advantages and beneficial effects that:

the invention utilizes the thiourethane tail liquid to prepare the critical saturated aqueous solution of sodium thioglycolate, and the saturated solution can be directly used, thereby avoiding the characteristics of high energy consumption and unstable moisture tendency of the production of the solid product of sodium thioglycolate; the prepared sodium thioglycolate critical saturated aqueous solution has high concentration and purity, does not contain other impurities, and particularly does not contain thiourethane. The invention fully utilizes the tail liquid of thiourethane, recovers thioglycollic acid to the maximum extent, and prepares the high-concentration critical saturated aqueous solution of sodium thioglycollate; the reaction heat generated in the sodium hydroxide reaction process is directly utilized in the reaction process, and the extraction organic solvent is recovered by adopting a reduced pressure heating mode, so that the energy is saved and the environment is protected.

Detailed Description

The invention is further illustrated and described below by means of specific examples.