Carbon dioxide capture by sodium hydroxide-glycerol aqueous solution in a rotating packed bed

Abstract

Abstract Carbon dioxide capture by chemical absorption has been one of the most popular approaches. However, low solubility of CO2 in water and high energy demand for absorbent regeneration hinder its feasibility. In this study, glycerol, a biodiesel waste by-product, was added to sodium hydroxide (NaOH) aqueous solution to relax these drawbacks, and to serve as an efficient absorbent in a rotating packed bed (RPB) for CO2 capture. The experimental results suggested that the addition of glycerol in the NaOH aqueous solution boosted the overall CO2 absorption efficiency to more than 90% easily. Under the high G (rotating speed) condition, the (chemical) enhancement factor could go up to more than 50. Furthermore, at same NaOH concentration, the mass transfer coefficients (KGa) could be doubled even when the viscous glycerol was added because of intensified centrifugal field. It is clearly indicated that, in an RPB, glycerol addition in NaOH solution showed very positive effect on CO2 capture not only for better mass transfer performance but also for the potential utilization of biodiesel by-product.