Surface Response Optimization for Absorption of CO2 Bubbles in Sweetener Solution by the Gas-Liquid Mass Transfer Operation

There is a trend to produce soft drinks with new specifications by increasing the amount of carbon dioxide absorbed in them but within the permissible food specifications limits. The experimental investigation of physical absorption was conducted in a bubble column to determine carbon dioxide absorption yield (YCO2) and volumetric mass transfer coefficients (Kla) to the liquid phase. The aim was to quantify the impact and optimization of the gas diffuser pore size, absorbent solution's temperature, gas flow rate, sucrose concentration, and their interaction on the responses of YCO2 and Kla. Box-Behnken design (BBD) in response surface methodology (RSM) is selected to determine this relationship. The Pareto chart was used to determine the experimental variables significantly impacting the observed responses. According to the analysis of variance (ANOVA), the absorbent solution's temperature, gas diffuser pore size, and sucrose concentration were important process variables that affect the absorption yield of carbon dioxide. All variables with interactions were found to affect volumetric mass transfer coefficients. The optimal responses for maximum YCO2 and Kla were 49.2 % and 0.455 1/min, respectively. The operational conditions were as follows: pore size of the diffuser (0.5 μm), gas flow rate (0.68 L/min), the temperature of absorbent (5 °C), and sucrose concentration (150 g/L).