Triethanolamine‐modified montmorillonite clay as a new adsorbent for CO2 capture: Characterization, adsorption, and RSM modeling

Abstract

AbstractIn this study, CO2 adsorption capacity was investigated by modified montmorillonite with triethanolamine due to its mechanical and chemical stability. The effect of operational parameters on CO2 adsorption capacity including temperature, pressure, and percentage triethanolamine was studied in the range of 30–70°C and 1–9 bar and 10–30%wt., respectively. Isothermal, kinetic, and thermodynamic analyses were performed by conventional method under equilibrium conditions. According to the R2 values from fitting the experimental data on the isothermal models, the Hill isotherm model was proposed for the unmodified and modified montmorillonite adsorbent. The results showed that the Elovich kinetic model provides the best fit for CO2 adsorption data for montmorillonite and triethanolamine‐modified montmorillonite. In the study of thermodynamic models, the positive slope of the Ln (Kd) diagram against 1/T indicates the thermal conductivity of the surface adsorption process. Optimal operating parameters were determined to obtain the highest adsorption capacity using the Design Expert software. For montmorillonite, the adsorption capacity obtained 219.86 mg/g at a temperature of 40°C and pressure of 7 bar, and for modified montmorillonite with triethanolamine, the optimal conditions for the input variables were 40°C, 7 bar, and 18.36%wt., respectively, and the adsorption capacity obtained was 248.55 mg/g.