CN115650514A - Method for recovering monoether from wastewater of preparation process of ethylene glycol monoallyl ether - Google Patents

Abstract

A method for recovering monoether from wastewater of a preparation process of ethylene glycol monoallyl ether comprises the following steps: 1) Taking ethylene glycol monoallyl ether preparation process wastewater, and adding an extracting agent A, wherein the extracting agent A is cyclohexane and/or n-hexane; 2) Taking a water layer, and adding soluble salt to obtain a saturated salt solution; 3) Adding an extracting agent B into the saturated salt solution, wherein the extracting agent B is trichloromethane; 4) And taking the organic layer, and removing the extracting agent B to obtain the monoether. The method has simple steps and low cost, the purity of the recovered monoether is more than or equal to 99 percent, and the comprehensive recovery yield of the monoether reaches more than 99 percent.

Description

Method for recovering monoether from wastewater of preparation process of ethylene glycol monoallyl ether

Technical Field

The invention relates to the field of chemical industry, and particularly relates to a method for recovering monoether from wastewater of a preparation process of ethylene glycol monoallyl ether.

Background

The ethylene glycol monoallyl ether (referred to as monoether hereinafter) is synthesized by taking ethylene glycol and chloropropene as raw materials. The wastewater generated in the synthesis process contains about 20% of organic matters (mainly monoethers, glycol bisallyl ethers (diethers), allyl alcohol and glycol), COD is usually as high as 40 ten thousand mg/L, and serious environmental pollution problems are generated.

The monoether product (8-15%) remained in the waste water is the most pollution contribution, and is a fine chemical with higher value, if the monoether product with higher content in the waste water can be recovered, the economic benefit can be improved, the organic matter content in the waste water can be greatly reduced, the COD can be reduced, the pollution degree of the waste water can be reduced, and the next treatment of the waste water is facilitated.

Because the wastewater simultaneously contains by-product diether and target product monoether, the monoether and the diether are liquid substances at normal temperature, have similar structures, close boiling points and certain intersolubility, and can form an azeotrope with a close boiling point with water, the three substances are difficult to be completely separated by a rectification mode. Therefore, when the monoether is recovered from the wastewater in a certain way, the problem of separating the monoether from water is solved, and the complete separation of the residual diether in the monoether is considered, so that the high-purity monoether recovered product can be obtained.

Disclosure of Invention

The invention aims to provide a method for recovering monoether as the largest pollutant from wastewater generated in the preparation process of ethylene glycol monoallyl ether to greatly reduce the pollution load of the wastewater by aiming at the defect of lack of effective and low-cost treatment technology for the wastewater generated in the preparation process of the ethylene glycol monoallyl ether, the method has simple steps and low cost, the purity of the recovered monoether is more than or equal to 99 percent, and the comprehensive recovery rate of the monoether is more than 99 percent.

The technical scheme of the invention is as follows: a method for recovering monoether from wastewater of a preparation process of ethylene glycol monoallyl ether comprises the following steps:

1) Taking ethylene glycol monoallyl ether preparation process wastewater, and adding an extracting agent A, wherein the extracting agent A is cyclohexane and/or n-hexane;

2) Taking a water layer, and adding soluble salt to obtain a saturated salt solution;

3) Adding an extracting agent B into the saturated salt solution, wherein the extracting agent B is trichloromethane;

4) And taking the organic layer, and removing the extracting agent B to obtain the monoether.

Further, the method also comprises a step 5), and the monoether obtained is rectified to obtain a monoether product.

Preferably, the extractant A in the step 1) is added into the process wastewater in multiple batches.

Further, the extractant A in the step 1) is divided into a plurality of parts and is sequentially added into the process wastewater.

Further, the soluble salt in the step 2) is sodium chloride, and the sodium chloride is a byproduct in the preparation process of the ethylene glycol monoallyl ether.

Preferably, the extractant B in the step 3) is added into the saturated salt solution in multiple batches.

Further, the extractant B in the step 3) is divided into a plurality of parts and is sequentially added into the saturated salt solution.

Further, fractions at 158 ℃ are collected by rectification to obtain monoether single products.

Further, the organic layer is taken in the step 1), and the diether and the extractant A are recovered by distillation.

Further, the wastewater from the process of preparing ethylene glycol monoallyl ether in step 1) contains 10.1-13.5wt% of monoether, 1.7-2.5wt% of diether, 7.2-8.4wt% of ethylene glycol, 0.3-0.5wt% of allyl alcohol and the balance of water.

Adopt above-mentioned technical scheme to have following beneficial effect:

1. the method for recovering monoether in the invention firstly utilizes the extracting agent A to remove most of the impurity diether, the other solutes are almost unchanged, and the monoether has certain polarity and water solubility, the solubility of the monoether is reduced by adding soluble salt, finally the monoether is separated by utilizing the extracting agent B, and finally the monoether product is obtained by distillation. The whole recovery process is simple and efficient, and the used extracting agent A, the used salt substances and the used extracting agent B are low in price and low in recovery cost. The organic content in the wastewater after the monoether and the diether are separated is greatly reduced, the COD value of the wastewater is also reduced, and extremely favorable conditions are created for further advanced wastewater treatment. In addition, the diether and the monoether are respectively recovered, so that the economic value is effectively improved.

2. The invention divides the extractant A into a plurality of times, especially into a plurality of parts, and then the parts are sequentially added into the wastewater, the extraction times are usually more than or equal to 4 times, and the extraction rate of the diether is more than 95 percent.

3. The extraction agent B is divided into a plurality of times, particularly divided into a plurality of parts, and the parts are sequentially added into a saturated salt solution, the extraction time is usually more than or equal to 3 times, and the extraction rate of monoether is more than 99 percent.

4. The invention utilizes the byproduct sodium chloride of the preparation process of the ethylene glycol monoallyl ether as soluble salt, adds the soluble salt into the separated water layer, does not need extra cost, and can further improve the yield of the target product monoether because the byproduct sodium chloride carries a large amount of monoether, diether and other substances.

The applicant tests and verifies that the comprehensive recovery rate of the monoether in the recovery method of the invention reaches more than 99 percent, and the purity of the recovered monoether reaches more than 99 percent.

The following description will be further described with reference to specific embodiments.

Detailed Description

EXAMPLE 1 recovery of the monoether

The content of main pollutants in the wastewater of the preparation process of the ethylene glycol monoallyl ether used in the example 1 is shown in the table 1-1,

TABLE 1-1 content of major contaminants in Process wastewater

1) Adding 1000ml of process wastewater into a separating funnel, adding a total of 400ml of cyclohexane for extraction four times (each time 100 ml), taking a water layer, and detecting that the content of main pollutants in the water layer is shown in a table 1-2

TABLE 1-2 content of main contaminants in wastewater after cyclohexane extraction

2) 300g of sodium chloride by-produced in the process was added to the water layer, and dissolved by stirring, and then 750ml of chloroform in total was added in three times (250 ml each) to extract. The organic layer was taken and the chloroform was separated by distillation to give 130.5g of crude monoether, which was found to contain 94% monoether, 0.4% diether, and about 5% other impurities. The content of main pollutants in the obtained water layer is shown in tables 1-3 by detection

TABLE 1-3 main contaminant content in waste water after chloroform extraction

The obtained monoether crude product is rectified, and fractions at 158 ℃ are collected to obtain 124.2g of monoether product after single rectification, the single recovery rate is 92%, and the purity is 99.5%. And adding the residual product at the bottom of the kettle into the next batch of monoether crude products, and rectifying and purifying the mixture, wherein the multiple comprehensive recovery rate is over 99 percent.

Example 2 recovery of the monoether

The content of main pollutants in the wastewater of the preparation process of the ethylene glycol monoallyl ether used in the example 2 is shown in the table 2-1,

TABLE 2-1 content of major contaminants in Process wastewater

1) Adding 1000ml of process wastewater into a separating funnel, adding a total of 400ml of cyclohexane for extraction four times (each time 100 ml), taking a water layer, and detecting that the content of main pollutants in the water layer is shown in a table 2-2

TABLE 2-2 content of main contaminants in wastewater after cyclohexane extraction

2) 300g of sodium chloride by-produced in the process was added to the water layer, and dissolved by stirring, and then 750ml of chloroform in total was added in three times (250 ml each) to extract. The organic layer was taken and chloroform was separated by distillation to give 112.2g crude monoether, 88% monoether, 0.5% diether and about 11% other impurities. The content of main pollutants in the obtained water layer is shown in tables 1-3 by detection

TABLE 2-3 main contaminant content in waste water after chloroform extraction

And rectifying the obtained monoether crude product, and collecting fractions at 158 ℃ to obtain 92.6g of monoether product subjected to single rectification, wherein the single recovery rate is 91 percent, and the purity is 99.2 percent. And adding the residual product at the bottom of the kettle into the next batch of monoether crude products, and rectifying and purifying the mixture, wherein the multiple comprehensive recovery rate is over 99 percent.

Comparative example 1 recovery of the monoether

The same waste water as in example 1 was extracted and recovered by the extractant B without performing the first extraction with the extractant a.

Taking 1000ml of wastewater, adding 300g of the byproduct sodium chloride in the process, stirring and dissolving, and then adding 750ml of chloroform in total for extraction in three times (250 ml each time). The organic layer was taken and the chloroform was separated by distillation to give 157.5g of crude monoether, which was detected to have a monoether content of 84%, a diether content of 10%, and other impurities of about 6%. The water layer obtained is detected to have main pollutant content shown in Table 3

TABLE 3 content of main pollutants in waste water after chloroform extraction

The obtained crude monoether is rectified, and fractions at 158 ℃ are collected to obtain 116.1g of monoether product with the purity of 96.1% (wherein the content of diether is 3.5%).

Claims (10)

1. A method for recovering monoether from wastewater of a preparation process of ethylene glycol monoallyl ether is characterized by comprising the following steps:

1) Taking ethylene glycol monoallyl ether preparation process wastewater, and adding an extracting agent A, wherein the extracting agent A is cyclohexane and/or n-hexane;

2) Taking a water layer, and adding soluble salt to obtain a saturated salt solution;

3) Adding an extracting agent B into the saturated salt solution, wherein the extracting agent B is trichloromethane;

4) Taking the organic layer, and removing the extractant B to obtain the monoether.

2. The method for recovering the monoether from the wastewater from the preparation process of the ethylene glycol monoallyl ether according to claim 1, further comprising the step 5) of rectifying the obtained monoether to obtain a monoether product.

3. The method for recovering monoether from the wastewater from the process for preparing ethylene glycol monoallyl ether according to claim 1, wherein the extractant A in step 1) is added to the process wastewater in multiple batches.

4. The method for recovering monoether from the wastewater from the process for preparing ethylene glycol monoallyl ether according to claim 3, wherein the extractant A in step 1) is divided into a plurality of parts, and the parts are sequentially added into the process wastewater.

5. The method for recovering monoether from the wastewater from the preparation process of ethylene glycol monoallyl ether according to claim 1, wherein the soluble salt in step 2) is sodium chloride, and the sodium chloride is a byproduct of the preparation process of ethylene glycol monoallyl ether.

6. The method for recovering monoether from the wastewater from the preparation process of ethylene glycol monoallyl ether according to claim 1, wherein the extractant B in step 3) is added to the saturated salt solution in multiple batches.

7. The method for recovering monoether from the wastewater of the preparation process of ethylene glycol monoallyl ether according to claim 6, wherein the extractant B in step 3) is divided into a plurality of portions, and the portions are sequentially added to the saturated salt solution.

8. The method for recovering monoether from the wastewater from the preparation process of ethylene glycol monoallyl ether according to claim 2, wherein the fraction at 158 ℃ is collected by rectification to obtain monoether monomers.

9. The method for recovering monoether from the wastewater of the preparation process of ethylene glycol monoallyl ether according to claim 1, wherein the organic layer obtained in step 1) is distilled to recover diether and extractant A.

10. The method for recovering monoether from wastewater from the preparation of ethylene glycol monoallyl ether according to claim 1

The method is characterized in that the wastewater of the process for preparing the ethylene glycol monoallyl ether in the step 1) contains 10.1 to 13.5 weight percent of monoether,

1.7-2.5wt% of diether, 7.2-8.4wt% of glycol, 0.3-0.5wt% of allyl alcohol and the balance of water.