2 research outputs found
Switchable Water: Microfluidic Investigation of Liquid–Liquid Phase Separation Mediated by Carbon Dioxide
Increase
in the ionic strength of water that is mediated by the
reaction of carbon dioxide (CO<sub>2</sub>) with nitrogenous bases
is a promising approach toward phase separation in mixtures of water
with organic solvents and potentially water purification. Conventional
macroscale studies of this complicated process are challenging, due
to its occurrence via several consecutive and concurrent steps, mass
transfer limitation, and lack of control over gas–liquid interfaces.
We report a new microfluidic strategy for fundamental studies of liquid–liquid
phase separation mediated by CO<sub>2</sub> as well as screening of
the efficiency of nitrogenous agents. A single set of microfluidic
experiments provided qualitative and quantitative information on the
kinetics and completeness of water–tetrahydrofuran phase separation,
the minimum amount of CO<sub>2</sub> required to complete phase separation,
the total CO<sub>2</sub> uptake, and the rate of CO<sub>2</sub> consumption
by the liquid mixture. The efficiency of tertiary diamines with different
lengths of alkyl chain was examined in a time- and labor-efficient
manner and characterized with the proposed efficiency parameter. A
wealth of information obtained using the MF methodology can facilitate
the development of new additives for switchable solvents in green
chemistry applications
Microfluidic Studies of CO<sub>2</sub> Sequestration by Frustrated Lewis Pairs
Frustrated
Lewis pairs (FLPs) comprising sterically hindered Lewis
acids and bases offer the capability to reversibly capture CO<sub>2</sub> under mild reaction conditions. The determination of equilibrium
constants and thermodynamic properties of these reactions should enable
assessment of the efficiency of a particular FLP system for CO<sub>2</sub> sequestration and provide insights for design of new, efficient
formulations of FLP catalysts for CO<sub>2</sub> capture. We have
developed a microfluidic approach to studies of FLP–CO<sub>2</sub> reactions, which provides their thermodynamic characterization
that is not accessible otherwise. The approach enables the determination
of the equilibrium reaction constants at different temperatures, the
enthalpy, the entropy, and the Gibbs energy of these reactions, as
well as the enhancement factor. The microfluidic methodology has been
validated by applying it to the well-characterized reaction of CO<sub>2</sub> with a secondary amine. The microfluidic approach can be
applied for fundamental thermodynamic studies of other gas–liquid
reactions