CO₂ absorption kinetics of 4-diethylamine-2-butanol solvent using stopped-flow technique

In the present work, a stopped-flow apparatus was used to determine the CO₂ absorption kinetics of 4-diethylamine-2-butanol (DEAB) in terms of observed pseudo-first-order rate constant (k₀) and second order reaction rate constant (k₂). The experiments were done using DEAB in the concentration range of 0.10-0.90 kmol/m³, and a temperature range of 293-313 K. The pK_a of DEAB was also experimentally determined over a temperature range of 278-333 K. The Brønsted relationship between the reaction rate constant obtained from the stopped-flow apparatus and pK_a obtained from experimental determination was then evaluated. The results showed that the Brønsted correlation could predict the absorption rate constant with an AAD of 8.6%, which is within an acceptable range of 10%. By comparing through different evaluation techniques such as k₂, pK_a and ^ΔrGm°, it was observed that DEAB has faster reaction kinetics than those of conventional tertiary amines, namely, DEMEA, DMMEA and MDEA.