Aqueous amine-based solutions are the cheapest currently employed solvents to capture CO₂ emitted from industrial processes. CO₂ capture involves flowing flue gas through a solution containing a relatively nontoxic compound such as monoethanolamine (MEA) that reacts selectively with CO₂. Understanding the properties that are essential for efficient CO₂ capture will be of great relevance for the development of more energy-efficient processes and the design of capture solutions.

John Hemminger and colleagues, University of California — Irvine, USA, have studied the role of the solution–gas interface in this reaction as it is of key importance for properly modeling absorption kinetics. Their results support a model in which CO₂ encounters pure MEA at the solution surface, and the reaction products and protonated MEA — formed by MEA reacting with CO₂ and with water — move into the bulk of the solution once they are formed.

This implies that a higher concentration of neutral MEA at the solution surface would increase the scavenging rate for CO₂, and allow more efficient CO₂ capture.

• CO₂ Capture in Amine-Based Aqueous Solution: Role of the Gas–Solution Interface
  T. Lewis, M. Faubel, B. Winter, J. C. Hemminger,
  Angew. Chem. Int. Ed. 2011.
  DOI: 10.1002/anie.201101250