Investigation of carbon dioxide absorption with glycerol and glycerol + sodium hydroxide hybrid solutions using stirred cell reactor

Abstract

The major effect of global warming is accepted as excessive carbon dioxide (CO₂) emission. The absorption process is widely used to reduce CO₂ emission and capture it at the source. This study investigated glycerol, a biodiesel waste by-product, for CO₂ absorption. Glycerol has a high boiling point and is very soluble in water. It is a suitable solvent for CO₂ absorption due to its low vapor pressure, low volatility, ease of access, and low solvent loss. The studies were performed using a stirred cell reactor and experiments were carried out at ambient temperature (20^oC) and atmospheric pressure (91 kPa). In experiments, the total CO₂ absorption capacities and dissolution rates were investigated using 5–40 wt% aqueous glycerol solutions and also using hybrid solvents by the equi-volume mixing of them to 0.5 M aqueous solution of sodium hydroxide (NaOH). As a result, 5, 10, and 15 wt% glycerol and 0.5 M NaOH hybrid solutions had an increasing trend on CO₂ absorption capacity and rate of absorption, in which the best results gave at 15 wt% glycerol+0.5 M NaOH between hybrid solutions. In addition, using glycerol for CO₂ capture processes has great potential in terms of waste management of biodiesel process. Density and viscosity of all solutions were determined by experimentally. Functional groups were also determined by FTIR analysis of pure and CO₂-loaded glycerol and glycerol + NaOH hybrid solutions.