A simple pH-based method for estimation of CO2 absorbed in alkanolamines

CO2 is recognized as a major contributor of global warming. We report a facile, sensitive and accurate method for estimating CO2 content in the alkanolamine solvents. It can be applied to a host of alkanolamine solvents as well as solvent mixtures for screening for prospective absorbent for CO2 capture. In this method, pH of the CO2-loaded absorbent sample is measured and referred to a “reference pH graph” of corresponding amine with sulphuric acid that is constructed under specific conditions. The authenticity of the method was validated from known amounts of CO2 added in the form of CO2-saturated water to three different types of alkanolamines i.e. the primary (monoethanolamine, MEA), secondary (diethanolamine, DEA) and tertiary (triethanolamine, TEA) alkanolamines. The method was compared with known methods and found to be better in terms of accuracy. Keywords: CO2 estimation, pH, pKa, Alkanolamines, Gas absorption.