Determine whether interfacial enrichment causes additional mass-transfer resistance

Determine whether an additional gas–liquid interfacial mass-transfer resistance exists in carbon dioxide–1-butanol absorption and whether that resistance is caused by enrichment of carbon dioxide at the vapor–liquid interface.

Background

The study compares diffusion coefficients of carbon dioxide in 1-butanol measured with a pressurized laminar jet apparatus (LJA) and pulsed-field-gradient nuclear magnetic resonance (PFG-NMR). The LJA values are systematically lower than the PFG-NMR reference values, and the authors report that experimental uncertainties and several modeling or transport effects do not adequately explain the discrepancy. Calculations using the PCP-SAFT equation of state combined with density-gradient theory predict substantial carbon-dioxide enrichment at the vapor–liquid interface. The authors therefore identify the existence and physical origin of an additional interfacial mass-transfer resistance as an unresolved issue requiring experimental and theoretical investigation.