Method and device for recovering isopropanol-containing dmsO waste liquid

Abstract

The application discloses a kind of DMSO waste liquid recovery methods containing isopropanol, comprising the following steps: (1) DMSO waste liquid containing isopropanol is passed into crude distillation kettle, after adding lye to adjust pH, crude distillation treatment is carried out, fraction one and crude distillation residual liquid are obtained;(2) fraction one is passed into freezer and is subjected to freezing crystallization treatment, then centrifugal separation is carried out, solid and filtrate are obtained, solid is subjected to vacuum drying treatment, DMSO finished product is obtained, filtrate is passed into supergravity rectification device and is subjected to rectification treatment, fraction two and rectification residual liquid are obtained;(3) fraction two is passed into pervaporation membrane group and is subjected to dehydration treatment, isopropanol finished product is obtained.In the application, after neutralization, separation is carried out by crude distillation, the problem of low efficiency and high cost of traditional resin adsorption process is solved, the waste liquid is not heated and separated by freezing crystallization in the application, energy consumption is greatly saved, the process device of the application is simple, dimethyl sulfoxide and isopropanol can be effectively recovered, the application is easy to operate, and industrial production application is facilitated.

Description

Technical Field

[0001] This invention relates to the field of waste liquid treatment technology, and in particular to a method and apparatus for recovering DMSO waste liquid containing isopropanol. Background Technology

[0002] Wet electronic chemicals are widely used in etching and cleaning processes in the semiconductor industry. Inorganic etching solutions, such as strong acids like nitric acid, sulfuric acid, and hydrochloric acid, are commonly used for etching circuit boards, while organic solvents, such as dimethyl sulfoxide (DMSO) and isopropanol, are often used in circuit board cleaning processes due to their good solubility and low toxicity. These solvents help remove oxide layers from circuit board surfaces, improving solderability and reliability. Semiconductor companies generate large quantities of cleaning and etching wastewater, some of which exists as mixtures. These wastewaters contain organic cleaning solutions, acidic etching solutions, and metallic impurities. Improper disposal can have severe environmental impacts. Typical treatment involves neutralizing this wastewater before biochemical treatment, but this requires large amounts of liquid alkali, resulting in high treatment costs.

[0003] Invention patent CN114213290A discloses a separation and purification process for DMSO-containing organic waste liquid. This process involves adding a stabilizer to the organic waste liquid and then recovering the DMSO through distillation and molecular sieve dehydration. However, distillation has high energy consumption, and molecular sieve dehydration efficiency is low, resulting in high material costs. Invention patent CN115784952A provides a purification process for electronic-grade dimethyl sulfoxide. This process uses ion exchange resin to remove metal ions and then purifies the product through distillation to obtain electronic-grade dimethyl sulfoxide. However, ion exchange resin is expensive, and distillation has high energy consumption. Invention patent CN119528696A discloses an industrial-grade isopropanol azeotropic distillation dehydration method. This method uses dichloromethane as an azeotropic agent for azeotropic distillation dehydration, and then uses molecular sieves for dehydration after the azeotropic agent has been used. This process has high energy consumption, and the treatment of the used azeotropic agent is complex and costly. Summary of the Invention

[0004] The main objective of this invention is to provide a method and apparatus for recovering DMSO waste liquid containing isopropanol, so as to effectively recover dimethyl sulfoxide and isopropanol, with low energy consumption and convenient operation.

[0005] To achieve the above objectives, the present invention provides a method for recovering DMSO waste liquid containing isopropanol, comprising the following steps: (1) Pass the DMSO waste liquid containing isopropanol into the crude distillation kettle, add alkali solution to adjust the pH and then carry out crude distillation treatment to obtain fraction one and crude distillation residue; (2) The first fraction is passed into a freezer for freezing and crystallization, then centrifuged to obtain a solid and a filtrate. The solid is vacuum dried to obtain DMSO product. The filtrate is passed into a high gravity distillation apparatus for distillation to obtain the second fraction and distillation residue. (3) The second fraction is passed into the pervaporation membrane group for dehydration treatment to obtain isopropanol product.

[0006] Furthermore, in the DMSO waste liquid containing isopropanol, the DMSO content is 30-50 wt%, the isopropanol content is 10-20 wt%, the sulfuric acid content is 1-3 wt%, the nitric acid content is 0.5-1 wt%, the copper ion content is 1000-2000 mg / L, and the iron ion content is 1500-2500 mg / L.

[0007] Furthermore, in step (1), the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide, and the pH is adjusted to 6-7.

[0008] Furthermore, in step (1), the conditions for the coarse steaming treatment are a temperature of 120 to 130°C and a pressure of -0.005 to -0.01 MPa.

[0009] Furthermore, in step (2), the conditions for the freeze crystallization treatment are a temperature of 1 to 5°C and a time of 0.5 to 1 hour.

[0010] Furthermore, the freeze crystallization process is carried out under ultrasonic conditions at a frequency of 20–30 kHz.

[0011] Furthermore, in step (2), the conditions for vacuum drying are a temperature of 60 to 80°C and a pressure of -0.005 to -0.01 MPa.

[0012] Furthermore, in step (2), the distillation conditions are a rotation speed of 15,000 to 25,000 rpm and a pressure of -0.005 to -0.01 MPa.

[0013] Furthermore, in step (3), the pervaporation membrane of the pervaporation membrane group is HPDA, and the dehydration treatment conditions are module heating temperature of 70~80℃ and pressure of -0.005~-0.01Mpa.

[0014] The present invention also provides a DMSO waste liquid recovery device containing isopropanol, comprising a crude distillation kettle, a first condenser, a refrigerator, a centrifuge, a supergravity distillation device, a second condenser, a first reboiler, a pervaporation membrane assembly, and a third condenser connected in sequence. The refrigerator is equipped with an ultrasonic oscillator, the outlet of the centrifuge is connected to a dryer, and the bottom of the supergravity distillation device is connected to a second reboiler.

[0015] The design principle of this invention is as follows: This invention first adds liquid alkali to adjust the pH, so that the waste acid in the waste liquid is neutralized to generate sulfate and nitrate, and copper ions and iron ions are converted into hydroxide precipitates. Thus, during the crude distillation treatment, the waste acid and metal ions can be separated from the organic components to obtain fraction I, which mainly consists of DMSO, isopropanol and water. The crude distillation residue is disposed of as secondary waste.

[0016] Based on the difference in melting point between DMSO (18.5℃) and isopropanol (-88.5℃) and water (0℃), fraction one was passed into a freezer for freeze crystallization to generate DMSO crystals. After centrifugation, solid DMSO was obtained and vacuum dried to obtain the finished DMSO product. The remaining filtrate was passed into a high-gravity distillation apparatus for distillation to obtain fraction two, which was an azeotrope of isopropanol and water. The distillation residue was disposed of as wastewater.

[0017] Finally, fraction 2 is passed through a pervaporation membrane unit for dehydration to obtain isopropanol as the final product, and the residual liquid in the pervaporation membrane unit is treated as wastewater.

[0018] The beneficial effects of this invention are reflected in: This invention solves the problems of low efficiency and high cost of traditional resin adsorption processes by neutralizing and then separating through coarse evaporation. This invention separates DMSO through freeze crystallization, eliminating the need for heating the waste liquid and greatly saving energy. The selected high gravity distillation device has the advantages of high separation efficiency, low energy consumption and small footprint compared to traditional distillation columns. The selected pervaporation membrane can efficiently separate water from isopropanol and water azeotropes with low energy consumption and small footprint.

[0019] The process and equipment of this invention are simple, can effectively recover dimethyl sulfoxide and isopropanol, have low energy consumption, are easy to operate, and are convenient for industrial production applications. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of a method for recovering DMSO waste liquid containing isopropanol according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of a DMSO waste liquid recovery device containing isopropanol according to an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Crude distillation vessel; 2. Condenser I; 3. Refrigeration unit; 4. Centrifuge; 5. Ultra-gravity distillation apparatus; 6. Condenser II; 7. Reboiler I; 9. Pervaporation membrane assembly; 9. Condenser III; 10. Ultrasonic oscillator; 11. Dryer; 12. Reboiler II. Detailed Implementation

[0023] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0024] Unless otherwise specified, the raw materials, reagents or devices used in the following embodiments can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0025] This invention provides a method for recovering DMSO waste liquid containing isopropanol and an apparatus for implementing the method. See the process flow diagram for details. Figure 1 The structure of the device is shown in the figure. Figure 2 It includes a crude distillation vessel 1, a condenser 1 2, a refrigerator 3, a centrifuge 4, a high gravity distillation device 5, a condenser 2 6, a reboiler 1 7, a pervaporation membrane group 9, and a condenser 3 9 connected in sequence. The refrigerator 3 is equipped with an ultrasonic oscillator 10. The outlet of the centrifuge 4 is connected to a dryer 11. The bottom of the high gravity distillation device 5 is connected to a reboiler 2 12. The pervaporation membrane of the pervaporation membrane group 9 is of model HPDA.

[0026] Example 1 Recovery of DMSO waste containing isopropanol 1000 kg of DMSO waste liquid containing isopropanol was fed into a coarse distillation vessel. The waste liquid contained 30 wt% DMSO, 10 wt% isopropanol, 2 wt% sulfuric acid, 0.7 wt% nitric acid, 1000 mg / L copper ions, and 1500 mg / L iron ions. A 20 wt% sodium hydroxide aqueous solution was added to adjust the pH of the waste liquid to 6. Then, coarse distillation was started at a temperature of 120℃ and a pressure of -0.005 MPa. The fraction obtained from the coarse distillation was condensed in a condenser and then fed into a freezer. The fraction was frozen and crystallized at a temperature of 1℃ and an ultrasonic oscillator frequency of 20 kHz for 0.5 h. The solid-liquid mixture was then fed into a centrifuge for centrifugal separation. The centrifuged solid was then placed in a dryer for vacuum drying at a temperature of 60℃, a pressure of -0.005 MPa, and a time of 1 h to obtain the DMSO product. The filtrate after centrifugation is fed into a high-gravity distillation apparatus for distillation at a speed of 15,000 rpm and a pressure of -0.005 MPa. The distillate fraction is an azeotrope of isopropanol and water, which is then passed into a vaporization permeation module for dehydration. The module is heated to 80°C and pressurized to -0.005 MPa to obtain isopropanol as the final product. The distillation residue from the high-gravity distillation apparatus and the residue from the vaporization permeation membrane are treated as wastewater.

[0027] Example 2 Recovery of DMSO waste containing isopropanol 1000 kg of DMSO waste liquid containing isopropanol was fed into a coarse distillation vessel. The waste liquid contained 40 wt% DMSO, 15 wt% isopropanol, 1 wt% sulfuric acid, 0.5 wt% nitric acid, 1500 mg / L copper ions, and 2000 mg / L iron ions. A 25 wt% potassium hydroxide aqueous solution was added to adjust the pH of the waste liquid to 6.5. Then, coarse distillation was started at a temperature of 125℃ and a pressure of -0.007 MPa. The fraction obtained from the coarse distillation was condensed in a condenser and then fed into a freezer. The fraction was frozen and crystallized at a temperature of 3℃ and an ultrasonic frequency of 25 kHz for 0.7 h. The solid-liquid mixture was then fed into a centrifuge for centrifugal separation. The centrifuged solid was then placed in a dryer for vacuum drying at a temperature of 70℃, a pressure of -0.007 MPa, and a time of 0.7 h to obtain the DMSO product. The filtrate after centrifugation is fed into a high-gravity distillation apparatus for distillation at a speed of 20,000 rpm and a pressure of -0.007 MPa. The distillate is an azeotrope of isopropanol and water, which is then passed into a vaporization permeation module for dehydration. The module is heated to 75°C and pressurized to -0.007 MPa to obtain isopropanol as the final product. The distillation residue from the high-gravity distillation apparatus and the residue from the vaporization permeation membrane are treated as wastewater.

[0028] Example 3 Recovery of DMSO waste containing isopropanol 1000 kg of DMSO waste liquid containing isopropanol was fed into a coarse distillation vessel. The waste liquid contained 50 wt% DMSO, 20 wt% isopropanol, 3 wt% sulfuric acid, 1 wt% nitric acid, 2000 mg / L copper ions, and 2500 mg / L iron ions. A 30 wt% sodium hydroxide aqueous solution was added to adjust the pH of the waste liquid to 7. Then, coarse distillation was started at a temperature of 130℃ and a pressure of -0.01 MPa. The fraction obtained from the coarse distillation was condensed in a condenser and then fed into a freezer. It was frozen and crystallized at a temperature of 5℃ and an ultrasonic frequency of 30 kHz for 1 hour. The solid-liquid mixture was then fed into a centrifuge for centrifugal separation. The centrifuged solid was then placed in a dryer for vacuum drying at a temperature of 80℃, a pressure of -0.01 MPa, and a time of 0.5 hours to obtain the DMSO product. The filtrate after centrifugation is fed into a high-gravity distillation apparatus for distillation at a speed of 25,000 rpm and a pressure of -0.01 MPa. The distillate is an azeotrope of isopropanol and water, which is then passed into a vaporization permeation module for dehydration. The module is heated to 70°C and pressurized to -0.01 MPa to obtain isopropanol as the final product. The distillation residue from the high-gravity distillation apparatus and the residue from the vaporization permeation membrane are treated as wastewater.

[0029] The DMSO and isopropanol products obtained in Examples 1-3 were tested for their properties, and the results are shown in Tables 1 and 2. Table 1. Specifications of the prepared DMSO product Table 2. Specifications of the prepared isopropanol product It can be seen that the DMSO products prepared in Examples 1-3 meet the requirements of Type III dimethyl sulfoxide in GB / T 21395-2024, and the isopropanol products prepared meet the requirements of Type II superior grade isopropanol in GB / T 7814-2017. Furthermore, the recovery rates of DMSO in Examples 1-3 are 98.2%, 98.9%, and 98.5%, respectively, and the recovery rates of isopropanol are 98.1%, 98.4%, and 98.2%, respectively. This indicates that the present invention can effectively recover DMSO and isopropanol and prepare products that meet the standards.

[0030] In addition, the distillation residues of the supergravity distillation apparatus obtained in Examples 1-3 were tested, and the DMSO contents were 0.2 wt%, 0.1 wt%, and 0.2 wt%, respectively.

[0031] Comparative Example 1 Recovery of DMSO waste containing isopropanol This comparative example was performed using the same method as Example 1, except that the refrigeration temperature was adjusted to 0°C. The final DMSO product obtained in this comparative example had a moisture content of 0.2 wt%, which does not meet the national standard for DMSO products.

[0032] Comparative Example 2 Recovery of DMSO waste containing isopropanol This comparative example was operated in the same manner as in Example 1, except that the refrigeration temperature was adjusted to 6°C. The final distillation residue from the centrifugal distillation apparatus obtained in this comparative example had a DMSO content of 0.8 wt%, resulting in a high COD in the wastewater and a reduced DMSO recovery rate of only 93.7%.

[0033] Comparative Example 3 Recovery of DMSO waste containing isopropanol This comparative example was operated in the same manner as in Example 1, except that the ultrasonic oscillator was not activated during the freeze crystallization process. The final distillation residue from the centrifugal distillation apparatus obtained in this comparative example was found to contain 1.5 wt% DMSO, resulting in a high COD in the wastewater and a reduced DMSO recovery rate of only 90.5%.

[0034] Comparative Example 4 Recovery of DMSO waste containing isopropanol This comparative example was conducted using the same method as Example 1, except that a 20wt% sodium hydroxide aqueous solution was added to adjust the pH of the waste liquid to 5. The final DMSO product obtained in this comparative example was light blue in color and had a high copper ion content, which did not meet the national standard for DMSO products.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recovering DMSO waste liquid containing isopropanol, characterized in that, Includes the following steps: (1) The DMSO waste liquid containing isopropanol was passed into the crude distillation kettle, and after adjusting the pH with alkali solution, it was subjected to crude distillation to obtain fraction one and crude distillation residue. (2) The first fraction is passed into a freezer for freezing and crystallization, then centrifuged to obtain a solid and a filtrate. The solid is vacuum dried to obtain DMSO product. The filtrate is passed into a high gravity distillation apparatus for distillation to obtain the second fraction and distillation residue. (3) The second fraction is passed into the pervaporation membrane group for dehydration treatment to obtain isopropanol product.

2. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1, characterized in that, The DMSO waste liquid containing isopropanol has a DMSO content of 30-50 wt%, an isopropanol content of 10-20 wt%, a sulfuric acid content of 1-3 wt%, a nitric acid content of 0.5-1 wt%, a copper ion content of 1000-2000 mg / L, and an iron ion content of 1500-2500 mg / L.

3. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (1), the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide, and the pH is adjusted to 6-7.

4. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (1), the conditions for the coarse steaming treatment are a temperature of 120 to 130°C and a pressure of -0.005 to -0.01 MPa.

5. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (2), the conditions for the freeze crystallization treatment are a temperature of 1 to 5°C and a time of 0.5 to 1 hour.

6. The method for recovering DMSO waste liquid containing isopropanol as described in claim 5, characterized in that, The freeze crystallization process was carried out under ultrasonic conditions at a frequency of 20–30 kHz.

7. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (2), the conditions for vacuum drying are a temperature of 60 to 80°C and a pressure of -0.005 to -0.01 MPa.

8. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (2), the distillation conditions are a rotation speed of 15,000 to 25,000 rpm and a pressure of -0.005 to -0.01 MPa.

9. The method for recovering DMSO waste liquid containing isopropanol as described in claim 1 or 2, characterized in that, In step (3), the pervaporation membrane of the pervaporation membrane group is HPDA, and the dehydration treatment conditions are module heating temperature of 70~80℃ and pressure of -0.005~-0.01Mpa.

10. A DMSO waste liquid recovery device containing isopropanol, characterized in that, The apparatus includes a crude distillation vessel, a first condenser, a refrigerator, a centrifuge, a supergravity distillation apparatus, a second condenser, a first reboiler, a pervaporation membrane assembly, and a third condenser, which are connected in sequence. The refrigerator is equipped with an ultrasonic oscillator, the centrifuge outlet is connected to a dryer, and the bottom of the supergravity distillation apparatus is connected to a second reboiler.

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