Optimization using central composite design for continuous absorption of CO₂ gas with green sodium silicate in a...

If absolutely nothing is taken to reduce carbon dioxide (CO₂) emissions, atmospheric concentrations of carbon dioxide will rise to 550 parts per million by 2050, which will have disastrous effects on the world's climate and food production. An apparatus has been designed and setup to convert CO₂ into a useful and vital product which was silica. The effect of different experimental factors on the compositions by weight percent of SiO₂ and Na₂CO₃ were studied including the CO₂ gas flow rate (1.037, 1.648 and 2.26 L/min), initial concentration of sodium silicate (Na₂SiO₃) solution (5, 7.5 and 10 %wt) and the packing size (15.95, 20.175, and 24.4 mm). An optimization process was performed using the Design Expert software program to achieve the optimum experimental conditions at which the maximum weight percent of SiO₂ (main product), the minimum weight percent of (Na₂CO₃) (side product) and the minimum reaction time were determined. From the optimization process, the maximum weight percent of SiO₂ (25.63 %), the minimum weight percent of (Na₂CO₃) (9.62 %) and the minimum reaction time (7.59 min) were achieved at the following optimum experimental conditions of CO₂ gas flow rate = 1.648 L/min, packing size = 24.4 mm and initial concentration of sodium silicate solution = 10 %wt.