Reaction kinetics of carbon dioxide and hydroxide in aqueous glycerol. (6th April 2017)

• Record Type: Journal Article
• Authors: Song, Di; Rochelle, Gary T.
• Is Part Of: Chemical engineering science. Volume 161(2017)
• Page Start: 151
• Page End: 158
• Publication Date: 2017-04-06
• Subjects: Viscosity -- Carbon dioxide -- Sodium hydroxide -- Glycerol -- Glyceroxide -- Reaction kinetics -- Surface depletion; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2016.11.048
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: CO2 absorption into aqueous glycerol/NaOH was measured in a wetted wall column. Glyceroxide reacts with CO2 7 times faster than hydroxide. In concentrated aqueous glycerol, glyceroxide is depleted at the interface. Abstract: The reaction kinetics of carbon dioxide and sodium hydroxide (nominally 0.1 N and 0.3 N) in aqueous glycerol were measured in a wetted wall column (WWC) at 20, 30, and 40 °C. Glycerol was added at 0–89 wt% to achieve a liquid viscosity ( μL ) of 0.89–65 cP. Compared to pure aqueous alkaline solution, the absorption rate ( kg ′) initially increased by 30% and then decreased rapidly by 75% with increasing glycerol. Based on the measured kg ′, a model was developed to calculate the overall reaction rate constant ( k Alk ), which resulted from the competing effects of CO2 /NaOH ( k OH - ) and CO2 /glyceroxide ( k Glycerol - ) reactions. The k Glycerol - was 6–7 times faster than k OH - . The non-monotonic trend of kg ′ was the combined effect of k Alk increasing and diffusivity ( D CO2 ) decreasing when glycerol increased. The effect of alkalinity depletion at the gas/liquid interface has been included in the kinetic model. The average depletion for 0.1 N NaOH is 4% for water and 20% for 89 wt% glycerol. Average depletion was less than 3% for 0.3 N NaOH. The addition of 0.05 N sodium carbonate has an insignificant effect on kg ′.