There are multiple techniques to enhance the calorific value of biogas by removing impurities, especially carbon dioxide (CO2). This study used a T-shaped microchannel to purify biogas by seawater containing 0.1 wt% of Iranian modified clinoptilolite zeolite and several precipitates (i.e., water distillation, phosphogypsum, power plant clarifier unit). These additives increase the alkalinity and CO2 absorption ability of seawater. Effects of temperature, liquid flow rate, and biogas flow rate on the CO2 removal efficiency have been investigated. The response surface methodology is also employed to construct a quadratic model to predict the CO2 removal efficiency as a function of these variables. The -value for all variables was less than 0.05, indicating that all four models were significant. Moreover, according to R2 values ranging from 0.9920 to 0.9997, the experimental CO2 absorption values have acceptable agreement with the model predictions. The maximum CO2 capture by seawater solutions containing zeolite and precipitates of phosphogypsum waste, plant clarifier, and water distillation at 30 C, in a liquid flow rate of 150 ml/h and a gas flow rate of 50 ml/min was 96.85, 96.01, 92.99, and 90.23%, respectively. The results achieved in this study are essential for the appropriate design of a micro-reactor for biogas upgrading and understanding the effect of operating conditions on its CO2 removal efficiency.
