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Accelerated Material-Efficient Investigation of Switchable Hydrophilicity Solvents for Energy-Efficient Solvent Recovery

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journal contribution
posted on 18.02.2020, 15:43 by Suyong Han, Keshav Raghuvanshi, Milad Abolhasani
In most chemical industries, solvent removal and recovery processes are heavily dependent on hazardous volatile solvents with energy-intensive distillation processes because of their ease of separation. An emerging promising alternative is implementing switchable solvents with on-demand and reversible switching of their physiochemical properties triggered by carbon dioxide (CO2). Utilization and widespread implementation of switchable solvents can dramatically reduce environmental risks and energy requirements for solvent removal and recovery processes. Despite intriguing characteristics of switchable solvents, the time- and material-intensive nature of conventional batch strategies has hindered a comprehensive understanding of this exciting class of green solvents. Herein, we report an accelerated time- and material-efficient (green) flow chemistry strategy for in situ fundamental and applied studies of CO2-mediated switchable solvents. Utilizing a highly gas-permeable membrane microreactor increases the gas–liquid interfacial area for CO2 injection, thereby enhancing the gas–liquid mass transfer (∼60 times faster equilibrium time than a batch reactor), while minimizing the chemical consumption (∼1000 times less than a batch reactor) and waste generation (∼1500 times less than a batch reactor) for each solvent-switching experiment. Utilizing the developed green flow chemistry strategy, we comprehensively study the effects of continuous and discrete process parameters on the efficiency and kinetics of hydrophilicity switching of switchable solvents. The intensified CO2-triggered switchable hydrophilicity solvent extraction process allows accurate material-efficient studies of switchable solvents and therefore will accelerate the development and adoption of distillation-free, green, and sustainable solvent recovery strategies in chemical industries.