Carbon dioxide capture by the green aqueous sodium hydroxide-glycerol solution in a gas-liquid microchannel contactor

Although organic solutions of alkali metal hydroxides have been considered a well-established technology for CO2 capture, they impose energy loss and a high corrosion rate due to the lack of suitable inhibitors. In this context, glycerol, as an abundant waste by-product of the biodiesel industry, was proposed to explore the CO2 absorption potential in the aqueous solution of sodium hydroxide-glycerol in a T-shaped microchannel contactor with an internal diameter of (ID=800 mu m). Applying Response Surface Methodology (RSM), the CO2 absorption experiments were performed under temperatures of 25-45celcius, with NaOH+Gly concentrations ranging from (0.2-0.8 M)+ (4-12 wt%), and the inlet gas flow rate of 100-300 ml/min. NaOH concentration was identified as a significant decisive variable on the CO2 absorption efficiency (eta) and the overall gas-phase mass transfer co-efficient (KGaV). The CO2 absorption efficiency of the developed hybrid solution was reported in the range of 29.28-98.40%. Besides, at concentrated alkali solution, adding glycerol from 4 to 12 wt% will raise the value of KGaV by more than 5.2 folds. This implies that the presence of glycerol in the aqueous NaOH solution not only intensifies the mass transfer performance but also declines the prevailing pollution and hazard wastes.