چكيده به لاتين
Today, the tendency to use inorganic adsorbents due to the low cost of adsorption of chimney gas from fossil fuel power plants has increased. The purpose of this work is to optimize the operating conditions of CO2 adsorption by a montmorillonite adsorbent in the batch reactor and optimize the adsorbent modified with amine groups to improve the adsorption capacity. The structural properties of the adsorbent have been presented by various techniques including SEM, BET, FTIR and XRD. Experimental design using response surface methodology was used to optimize the adsorption operating conditions. Three factors temperature and pressure were in the range of 30-70 ° C and 1-9 bar, respectively, and surface modifier weight percent (diethanolamine or triethanolamine) in the range of 10-30% w / w as input variables and absorption capacity (mg / g) and percentage of adsorption were considered as the response. The optimum conditions were introduced at the point where the adsorption capacity and percentage were as high as possible. For montmorillonite adsorbent, the optimum temperature and pressure are 40 ° C and 7 bar, respectively, and the adsorption capacity is 219.86 mg.g-1.Also, the optimum temperature, pressure, and weight percent of diethanolamine modified for montmorillonite modified by diethanolamine were 40 ° C and 7 bar and 15% w / w respectively and the adsorption capacity of 281.824 mg.g-1 was obtained. Also for the montmorillonite modified with triethanolamine the optimum conditions of input variables were 40 ° C and 7 bar and 20.53% w / w and 248.92 mg.g-1 adsorption capacity, respectively..In addition, additional experiments have been performed to investigate isothermal, kinetic and thermodynamic models of adsorption. According to the values of R2 for the montmorillonite adsorbent, the isotherm model is consistent with the Langmuir-Freundlich model which indicates the heterogeneity coefficient and generally indicates the adsorption mechanism with the heterogeneous surface of montmorillonite nanoparticles. The isotherm model for the modified montmorillonite adsorbent with diethanolamine and triethanolamine is in accordance with the Hill model, which indicates the equilibrium of the adsorbed link with the adsorption sites and the interaction of the sites. Evaluation of traditional models based on the values of R2 showed that in montmorillonite and montmorillonite modified with diethanolamine and triethanolamine, the Elovich model provides the best fit to CO2 capture data. This indicates that surface modification of the adsorbent with an additional adsorption mechanism In addition to providing diffusion. Positive slope of Ln (kd) vs. 1 / T diagrams for the study of thermodynamic models in montmorillonite and montmorillonite modified with diethanolamine and triethanolamine indicating negative values for enthalpy of process and exothermic adsorption process. In general, CO2 binding in modified montmorillonite appears to be more influenced by intrusion and by the formation of chemical bonds as a model intracellular diffusion.
