Absorption of carbon dioxide using a deep eutectic solvent in a packed bed column

The increase in atmospheric carbon dioxide is primarily attributed to the extensive consumption of fossil fuels, raising global concerns about the greenhouse effect and related problems. Separating, transferring, and then storing or consuming carbon dioxide is one of the ways to reduce its emission. In recent years, many activities have focused on surveying new types of solvents, such as ionic liquids and deep eutectic solvents (DES). A DES is generally composed of two or three components, capable of self-association, often through hydrogen-bond interactions, to form a eutectic mixture. A deep eutectic solvent consisting of a choline chloride and diethylene glycol mixture (ratio 1:3) has been used. The experiments were carried out in a packed bed filled with Raschig rings. Results show that the volumetric mass transfer coefficient on the liquid side clearly increased with the liquid flow rate, while exhibiting a marginal increase with the gas flow rate. The measured value of the liquid side volumetric mass transfer coefficient was (0.83 × 10⁻² to 1.37 × 10⁻²) s⁻¹. Volumetric mass transfer coefficients were determined and compared with published correlations in the literature. It showed good agreement with the experimental data, with a maximum relative error of less than 15%.