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Recovery method of esters in wastewater

A recovery method and technology for wastewater, applied in chemical instruments and methods, separation/purification of carboxylate, preparation of carboxylate, etc., can solve the problem of residual low-concentration isopropyl acetate isopropanol, inability to obtain purity, and many orders of magnitude. and other problems, to achieve the effect of reducing membrane area, high conversion rate and improving recycling efficiency

Pending Publication Date: 2019-07-23
NANTONG CELLULOSE FIBERS CO LTD +2
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the other hand, isopropyl acetate is easily decomposed into isopropanol and water during extraction and distillation.
[0004] The main problems in recovery include: during production, low concentration of isopropyl acetate remains in the raffinate phase, isopropanol obtained from decomposition and a large amount of water
This part of isopropyl acetate needs to be recovered and reused; the boiling point of isopropyl acetate and isopropanol is close, and the order of magnitude required for rectification and separation is large, and the energy consumption is large; isopropyl acetate, isopropanol and water form di Elementary or ternary azeotrope, ordinary distillation methods cannot obtain products with a purity higher than the azeotropic composition

Method used

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  • Recovery method of esters in wastewater

Examples

Experimental program
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Effect test

Embodiment 1

[0035] Embodiment one: the water content is about 95.5%wt in the waste water, and its technological process is as follows figure 1 shown.

[0036] An aqueous solution containing isopropyl acetate and isopropanol, wherein: isopropanol accounts for about 0.5%wt, and isopropyl acetate accounts for about 4%wt. A rectification tower 10 is used to separate most of the water. The output 103 from the tower bottom is mainly water and a small amount of residual acetic acid. The content of ester and alcohol solvent in the extraction 103 from the tower bottom is strictly controlled to <0.1%wt.

[0037] Isopropanol and water have higher boiling points, and 203 extracted from the bottom of tower 20 is isopropanol, water and azeotrope, and the content of ester solvent in 203 is strictly controlled to <0.1%wt. The output 202 at the top of the tower 20 is concentrated ester / alcohol / water mixed solvent.

[0038] 203 enters the tower 30 for further separation, 303 extracted from the bottom of ...

Embodiment 2

[0041] Embodiment two: the water content in the waste water is about 89.5%wt, and its technological process is as follows figure 1 shown.

[0042] An aqueous solution containing isopropyl acetate and isopropanol, wherein: isopropanol accounts for about 1.5%wt, and isopropyl acetate accounts for about 9.0%wt. A rectification tower 10 is used to separate most of the water. The output 103 from the tower bottom is mainly water and a small amount of residual acetic acid. The content of ester and alcohol solvent in the extraction 103 from the tower bottom is strictly controlled to <0.1%wt.

[0043] Isopropanol and water have higher boiling points, and 203 extracted from the bottom of tower 20 is isopropanol, water and azeotrope, and the content of ester solvent in 203 is strictly controlled to <0.1%wt. The output 202 at the top of the tower 20 is concentrated ester / alcohol / water mixed solvent.

[0044] 203 enters the tower 30 for further separation, 303 extracted from the bottom o...

Embodiment 3

[0047] Embodiment three: water content is about 83%wt in the waste water, and its technological process is as follows figure 1 shown.

[0048] An aqueous solution containing ethyl acetate and ethanol, wherein: ethanol accounts for about 12%wt, and ethyl acetate accounts for about 17.0%wt. The tower 10 is used to separate most of the water, and the 103 extracted from the tower kettle is mainly water and a small amount of residual acetic acid, and the content of ester and alcohol solvents in the 103 is strictly controlled to <0.1%wt.

[0049] The 203 extracted from the bottom of the tower 20 is ethanol, water and azeotrope, and the content of the ester solvent in the 203 is strictly controlled to <0.1%wt. The output 202 at the top of the tower 20 is concentrated ester / alcohol / water mixed solvent.

[0050] 203 enters tower 30 for further separation, 303 extracted from the bottom of the tower is water, and 302 extracted from the top of the tower is an azeotropic composition of e...

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Abstract

Disclosed is a recovery method of esters in wastewater. The method includes the following steps: separating most of water in the wastewater, and controlling the content of esters ad alcohols in the separated water less than 0.1 wt%; separating esters in a remaining ester / alcohol / water solution, and controlling the content of the esters in the remaining ester / water mixed solution after the esters are separated less than 0.1 wt%; separating water in the ester / alcohol / water solution separated in the second step by pervaporation treatment to obtain a mixture of esters and alcohol having s water content of less than 1 wt%; separating the high-purity target product esters from the mixture by distillation; and separating unreacted acids from esterification products and recycling the rest back tothe first step of wastewater treatment process. The recovery method of the esters in the wastewater can solve the problem of difficult separation of corresponding alcohols generated by decomposition of ester solvents, has the characteristics of high recovery efficiency, low energy consumption and low raw material consumption, and is especially suitable for use in wastewater solutions containing iso butyl acetate to recover the iso butyl acetate in the wastewater solutions.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and relates to waste water treatment and recycling technologies, in particular to a method for recycling esters in waste water. Background technique [0002] In some industrial production, waste water containing esters will be produced. For example, isopropyl acetate is a commonly used dehydrating agent in industry. It is mainly used as a solvent for coatings, printing inks, etc., and is also used as an extraction solvent for drugs and a solvent for chemical reactions. Wait. As a commonly used extractant, it is widely used in extraction and separation, and waste water containing esters is produced accordingly. [0003] During the manufacture of acetate fiber, dilute acetic acid is extracted and then rectified to recover pure acetic acid. Isopropyl acetate is one of the main extractants, and a small amount of ester solvent isopropyl acetate remains in the raffinate phase, and this part...

Claims

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Application Information

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IPC IPC(8): C07C67/48C07C67/56C07C67/54C07C67/08C07C69/14
CPCC07C67/08C07C67/48C07C67/54C07C67/56C07C69/14Y02P20/50
Inventor 梁银春于星王国华孙利辉徐静静
Owner NANTONG CELLULOSE FIBERS CO LTD
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