A Study on CO2 Absorption in Bubble Column Using DEEA/EEA Mixed Solvent

Abstract

Absorption of carbon dioxide in aqueous blends of alkanolamines prepared from renewable resources (DEEA/EEA), which can be produced from green materials, was explored. In addition, the scrubbing factor of CO2‐gas in alkaline solution was found to be excellent in a bubble‐ column, as compared with another scrubber. Thus, a continuous bubble‐column scrubber was used in this study. Therefore, a continuous bubble‐column scrubber absorbing CO2‐gas, using a DEEA/EEA mixed solvent as an absorbent under a pH‐stat condition, was used to search for the optimum process parameters by means of Taguchi's analysis. The process variables included the pH of the solution, gas‐flow rate, and concentration of solvent. From measured outlet CO2‐gas concentrations, absorption rate, removal efficiency, and overall mass‐transfer coefficient could be determined, with the aid of steady‐state material balance equation, as well as a two‐film model. Additionally, the liquid‐flow rate of DEEA /EEA was observed automatically through the action of a pH controller. The data obtained were in the range of 1.26x10 ‐4 ‐11.80x10 ‐4 (mol/s‐L), 0.0728‐0.8395(1/s), and 28‐98.66% for absorption rate, mass‐ transfer rate, and removal efficiency, respectively. According to S/N ratio, the significance sequence influencing the absorption rate was D(pH)>C (gas flow rate)>A(concentration of DEEA)>B(concentration of EEA), while the significance sequence for overall mass‐transfer coefficient was A>B>C>D.