Eco-friendly CO2 adsorbent by impregnation of diethanolamine in nanoclay montmorillonite

In this study, modification of the nanoclay montmorillonite adsorbent with diethanolamine and optimization of CO2 adsorption operating conditions to improve the adsorption capacity were carried out experimentally. The temperature, pressure, and weight percent of diethanolamine were considered in the range of 30−70 °C, 1−9 bar, and 10−30%wt, respectively, as input variables and adsorption capacity (mg/g) and adsorption percentage were considered as the responses in the response surface methodology. The maximum adsorption capacity was obtained 219.9 mg/g for montmorillonite adsorbent without modification at temperature and pressure of 30 °C and 9 bar, respectively. In addition, the optimum temperature, pressure, and weight percent of diethanolamine were obtained 30 °C and 9 bar and 22%wt, respectively, and the adsorption capacity was calculated 281.8 mg/g for modified montmorillonite with diethanolamine. Additionally, the adsorbent behavior was investigated using isotherm, kinetic, and thermodynamic modeling of the adsorption process. The results showed that, based on the obtained values of R2, Langmuir-Freundlich and Hill models have a better precision between isotherm models for the montmorillonite adsorbent without and with modification, respectively. Finally, the kinetic modeling result showed that the Elovich model is the best-proposed model for CO2 capture data.