Interfacial Insights into a Carbon Capture System: CO₂ Uptake to an Aqueous Monoethanolamine Surface

Monoethanolamine (MEA) is a benchmark scrubber for CO₂ gas emissions reductions. Preliminary studies have indicated surface monoethanolamine could influence the greater chemistry of CO₂ uptake. MEA is known to be surface active and orients at aqueous surfaces such that its nitrogen lone pair electrons are pointing toward the gas phase. This MEA orientation has the potential to facilitate CO₂ surface chemistry; however, a thorough description of the chemistry at play during this important carbon capture reaction is lacking. These studies investigate the surface behavior of MEA during CO₂ gas flow, monitoring product formation and species migration. A combination of experimental vibrational sum frequency spectroscopy (VSFS), surface tensiometry, molecular dynamics simulations, and density functional calculations are used to investigate this complex chemistry. CO₂ is shown to react with MEA, perturbing the interface and leading to the presence of carbamic acid in the surface region. However, throughout this chemistry the surface remains largely populated by unreacted MEA. These studies provide insight into this important carbon capture reaction and provide a framework for future work examining interfacial reactions and dynamics.