Search

US-12623184-B2 - Microfluidic device design for extraction and phase separation for organic solvent purification

US12623184B2US 12623184 B2US12623184 B2US 12623184B2US-12623184-B2

Abstract

A purification system for ionic liquid solvents includes an ionic liquid source that includes a first flow controller configured to provide a first flow stream at a first flow rate where the first flow stream including an ionic liquid requiring purification. An extraction liquid source provides a second flow stream including an extraction liquid that is immiscible with the ionic liquid. A mixing component is configured to mix the first flow stream and the second flow stream and output a mixed flow stream that includes a retentate phase and a permeate phase. A separator assembly includes a separation membrane interposed between a first flow channel assembly and a second channel assembly.

Inventors

  • BIN PAN
  • Noah Malmstadt

Assignees

  • UNIVERSITY OF SOUTHERN CALIFORNIA

Dates

Publication Date
20260512
Application Date
20231113

Claims (20)

  1. 1 . A purification system for ionic liquid solvents, the purification system comprising: an ionic liquid source that includes a first flow controller configured to provide a first flow stream at a first flow rate, the first flow stream including an ionic liquid requiring purification; an extraction liquid source that includes a second flow controller configured to provide a second flow stream at a second flow rate, the second flow stream including an extraction liquid that is immiscible with the ionic liquid; a mixing component configured to mix the first flow stream and the second flow stream and output a mixed flow stream that includes a retentate phase and a permeate phase; a separator assembly including a housing having a first flow channel assembly, a second flow channel assembly, an inlet, a first outlet, and a second outlet, the inlet configured to receive the mixed flow stream, the first outlet configured to output a retentate output flow stream, the separator assembly also including a separation membrane interposed between the first flow channel assembly and the second channel assembly, the separation membrane having a first face that contacts ionic liquid in the first flow channel assembly from the mixed flow stream and a second face contacting a permeate waste stream in the second flow channel assembly that is outputted from the second outlet; and an output flow controller configured adjust flow of the retentate output flow stream to a third flow rate.
  2. 2 . The purification system of claim 1 further comprising: a flow detector that measures homogeneity of the retentate output flow after separation; a spectrometer system configured to monitor concentrations of impurities in the retentate output flow stream; and a computing device in electrical communication with the first flow controller, the second flow controller, the flow detector, and the spectrometer system, the spectrometer system providing feedback to the computing device about concentrations of impurities in the retentate output flow stream such that the first flow rate, the second flow rate, and the third flow rate are adjustable to increase the purity of the retentate output flow stream.
  3. 3 . The purification system of claim 1 , wherein when the extraction liquid includes water or acidified water.
  4. 4 . The purification system of claim 1 , wherein when the separation membrane is hydrophilic, the retentate phase includes the ionic liquid, and the permeate phase includes the extraction liquid.
  5. 5 . The purification system of claim 1 , wherein when the separation membrane is hydrophilic, the retentate phase includes the extraction liquid, and the permeate phase includes the ionic liquid.
  6. 6 . The purification system of claim 1 , wherein the first flow rate, the second flow rate, and the third flow rate are adjustable to increase the purity of the retentate output flow stream in accordance with optimization of an objective function.
  7. 7 . The purification system of claim 6 , wherein the objective function is the following equation: Score = 100 - C 1 ⁢ log 10 ⁢ I 0 I ⁢ “ Extraction ⁢ Term ” - C 2 ⁢ max ⁡ ( SD ret , SD per ) ⁢ “ Separation ⁢ Term ” - C 3 ⁢ Q ES Q IL ⁢ “ Separation ⁢ Term ” where: C 1 , C 2 , and C 3 are numberical coefficients; I 0 is transmittance intensity for the ionic liquid requiring purification; I is transmittance intensity for the retentate output flow stream; SD ret and SD per are standard deviations for the retentate output flow stream and the permeate waste stream, respectively; and Q IL and Q ES are the first flow rate and the second flow rate (μL/min), respectively.
  8. 8 . The purification system of claim 1 , wherein the first flow channel assembly includes a herringbone flow channel.
  9. 9 . The purification system of claim 8 , wherein the first flow channel assembly includes a waved flow channel downstream of the herringbone flow channel.
  10. 10 . The purification system of claim 9 , wherein the second flow channel assembly includes a zigzagging flow channel.
  11. 11 . The purification system of claim 10 , wherein the herringbone flow channel, the waved flow channel, the inlet and the first outlet are least partially defined by and embedded in a first single material block.
  12. 12 . The purification system of claim 11 , wherein the zigzagging flow channel and the second outlet are at least partially defined by and embedded in a second single material block.
  13. 13 . The purification system of claim 12 , wherein the first single material block and the first single material block are independently composed of a polymer or resin.
  14. 14 . The purification system of claim 13 , wherein the first flow channel assembly and the second flow channel assembly are at least partially formed by 3D printing.
  15. 15 . The purification system of claim 11 , wherein the herringbone flow channel, the waved flow channel, and the zigzagging flow channel independently have a height from about 300 microns to 700 microns and a width from about 300 microns to 700 microns.
  16. 16 . The purification system of claim 11 , wherein the ionic liquid is a reaction solvent used in colloidal inorganic nanoparticle synthesis.
  17. 17 . A purification system for ionic liquid solvents, the purification system comprising: an ionic liquid source that includes a first flow controller configured to provide a first flow stream at a first flow rate, the first flow stream including an ionic liquid requiring purification; a separator assembly including a housing having a first flow channel assembly, a second flow channel assembly, an inlet, a first outlet, and a second outlet, the inlet configured to receive the first flow stream, the first outlet configured to output a retentate output flow stream, the separator assembly also including a separation membrane interposed between the first flow channel assembly and the second channel assembly, the separation membrane having a first face that contacts ionic liquid in the first flow channel assembly from the first flow stream and a second face contacting a permeate waste stream in the second flow channel assembly that is outputted from the second outlet; and an output flow controller configured adjust flow of the retentate output flow stream to a second flow rate.
  18. 18 . The purification system of claim 17 further comprising: a flow detector that that measures homogeneity of the retentate output flow after separation; a spectrometer system configured to monitor concentrations of impurities in the retentate output flow stream; and a computing device in electrical communication with the first flow controller, the flow detector, and the spectrometer system, the spectrometer system providing feedback to the computing device about concentrations of impurities in the retentate output flow stream such that the first flow rate, and the second flow rate are adjustable to increase the purity of the retentate output flow stream.
  19. 19 . The purification system of claim 17 , wherein the first flow rate, and the second flow rate are adjustable to increase the purity of the retentate output flow stream in accordance with optimization of an objective function.
  20. 20 . The purification system of claim 17 , wherein the first flow channel assembly includes a herringbone flow channel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. provisional application Ser. No. 63/424,244 filed Nov. 10, 2022, the disclosure of which is hereby incorporated in its entirety by reference herein. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under Grant No(s). CMMI-1728649, awarded by the National Science Foundation (NSF). The government has certain rights in the invention. TECHNICAL FIELD In at least one aspect, the present invention relates to microfluidic devices for purifying solvent, and in particular for purifying ionic solvents. BACKGROUND Ionic liquids (ILs) are molten salts consisting of organic or inorganic anions and organic cations with melting points below 100° C. and often below room temperature.1 ILs have gained significant attention as sustainable alternatives to traditional volatile organic compounds (VOCs) because they are non-flammable and have negligible vapor pressures, mitigating their emissions into the atmosphere and ultimately decreasing their environmental impact.2 ILs are widely employed in a variety of synthetic chemistries,3-7 including as solvents for inorganic nanoparticle syntheses.8-12 ILs are also known to exhibit an extraordinary ability to extract metal ions for extraction and recovery processes.13-17 However, the relatively high cost of ILs over traditional organic solvents greatly hinders their practical application in industrial processes.18 It is therefore essential to reuse or recycle ILs; techniques for IL recycling without degradation of IL quality have been a topic of considerable research. Oliveira and coworkers reported that 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM-NTf2) or 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) used as solvents for Fe3O4 magnetic nanoparticle synthesis could be recycled for more than 20 successive reactions.19 Karadaghi and coworkers succeeded in obtaining a constant quality of colloidal Pt nanoparticles using 5× recycled BMIM-NTf2 as solvent, and through a techno-economic analysis they demonstrated that the total cost of using recycled ILs can be as low as 10% of the cost of using a conventional organic solvent.20 While batch procedures for IL recycling are well understood, they often suffer from being labor-intensive, time-consuming, and highly variable. Flow methods have the potential to overcome these disadvantages, affording high reproducibility, speed, high throughput, and reduced environmental risks.21 One of the most advantageous features of continuous processes is that they enable automation to minimize human intervention and errors, and can be easily integrated with computer-aided optimization algorithms to maximize the output of interest. Self-optimizing, continuous flow techniques have typically been applied to synthetic chemistry operations;22-26 however, there are very few studies applying self-optimizing, feedback-enabled approaches to work-up processes such as the liquid-liquid extraction and separation needed for IL solvent recycling. Note that in this report we use the term “extraction” to describe the mass transfer of metal ions between the liquid phases and the term “separation” to describe the physical removal of one phase from the other. Other reports in the literature use the term “stripping” to refer to the transfer of metal ions out of the IL phase; our use of the term “extraction” is equivalent. Biphasic liquid-liquid separation for non-IL based systems has been broadly studied and utilized in microfluidics or millifluidics via configurations consisting of conventional gravity-based separators,27 direct Y-shaped branched outlets,28,29 capillaries,30-33 membrane separators,34-39 and other customized setups.38,40 Membrane separation, which harnesses Laplace pressure and differential wettability determined by the membrane materials to effectively separate immiscible liquids is widely used because of its versatility, relative ease of design and assembly, and superior separation performance.30 Although membrane separators have already showcased the power to separate diverse solvents (e.g., toluene37 and water), their ability to tackle ionic liquids remains untapped. SUMMARY In at least one aspect, a purification system for ionic liquid solvents is provided. The purification system includes an ionic liquid source that includes a first flow controller configured to provide a first flow stream at a first flow rate. The first flow stream includes an ionic liquid requiring purification. An extraction liquid source includes a second flow controller configured to provide a second flow stream at a second flow rate. The second flow stream includes an extraction liquid that is immiscible with the ionic liquid. A mixing component is configured to mix the first flow stream and the second flow stream and output a mixed flow stream. A separator assembly includes a housing having a first flo