title: Thiolene and SIFEL-based Microfluidic Platforms for Liquid-Liquid Extraction.
abstract: Microfluidic platforms provide several advantages for liquid-liquid extraction (LLE) processes over conventional methods, for example with respect to lower consumption of solvents and enhanced extraction efficiencies due to the inherent shorter diffusional distances. Here, we report the development of polymer-based parallel-flow microfluidic platforms for LLE. To date, parallel-flow microfluidic platforms have predominantly been made out of silicon or glass due to their compatibility with most organic solvents used for LLE. Fabrication of silicon and glass-based LLE platforms typically requires extensive use of photolithography, plasma or laser-based etching, high temperature (anodic) bonding, and/or wet etching with KOH or HF solutions. In contrast, polymeric microfluidic platforms can be fabricated using less involved processes, typically photolithography in combination with replica molding, hot embossing, and/or bonding at much lower temperatures. Here we report the fabrication and testing of microfluidic LLE platforms comprised of thiolene or a perfluoropolyether-based material, SIFEL, where the choice of materials was mainly guided by the need for solvent compatibility and fabrication amenability. Suitable designs for polymer-based LLE platforms that maximize extraction efficiencies within the constraints of the fabrication methods and feasible operational conditions were obtained using analytical modeling. To optimize the performance of the polymer-based LLE platforms, we systematically studied the effect of surface functionalization and of microstructures on the stability of the liquid-liquid interface and on the ability to separate the phases. As demonstrative examples, we report (i) a thiolene-based platform to determine the lipophilicity of caffeine, and (ii) a SIFEL-based platform to extract radioactive copper from an acidic aqueous solution.
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Sachit
authors.initials: S
authors.lastname: Goyal
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Amit V
authors.initials: AV
authors.lastname: Desai
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA ; Chemical and Biological Engineering, The University of Sheffield, Sheffield, United Kingdom.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Lewis
authors.affiliation: Radiological Sciences Division, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Ranganathan
authors.affiliation: Radiological Sciences Division, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Hairong
authors.initials: H
authors.lastname: Li
authors.affiliation: Radiological Sciences Division, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Dexing
authors.initials: D
authors.lastname: Zeng
authors.affiliation: Radiological Sciences Division, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Reichert
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Paul J A
authors.initials: PJ
authors.lastname: Kenis
keywords: Parallel-flow microfluidic platform; extraction of radiometals; functionalization of microchannels; lipophilicity of drugs; organic solvent compatibility; two-phase flow