Efficient CO2 adsorption using chitosan, graphene oxide, and zinc oxide composite
Farnoush Fathalian, Hamidreza Moghadamzadeh, Alireza Hemmati, Ahad Ghaemi
Abstract
Abstract This study was deeply focused on developing a novel CTS/GO/ZnO composite as an efficient adsorbent for CO 2 adsorption process. To do so, design of experiment (DOE) was done based on RSM-BBD technique and according to the DOE runs, various CTS/GO/ZnO samples were synthesized with different GO loading (in the range of 0 wt% to 20 wt%) and different ZnO nanoparticle’s loading (in the range of 0 wt% to 20 wt%). A volumetric adsorption setup was used to investigate the effect of temperature (in the range of 25–65 °C) and pressure (in the range of 1–9 bar) on the obtained samples CO 2 uptake capability. A quadratic model was developed based on the RSM-BBD method to predict the CO 2 adsorption capacity of the composite sample within design space. In addition, CO 2 adsorption process optimization was conducted and the optimum values of the GO, ZnO, temperature, and pressure were obtained around 23.8 wt%, 18.2 wt%, 30.1 °C, and 8.6 bar, respectively, with the highest CO 2 uptake capacity of 470.43 mg/g. Moreover, isotherm and kinetic modeling of the CO 2 uptake process were conducted and the Freundlich model (R 2 = 0.99) and fractional order model (R 2 = 0.99) were obtained as the most appropriate isotherm and kinetic models, respectively. Also, thermodynamic analysis of the adsorption was done and the ∆H°, ∆S°, and ∆G° values were obtained around − 19.121 kJ/mol, − 0.032 kJ/mol K, and − 9.608 kJ/mol, respectively, indicating exothermic, spontaneously, and physically adsorption of the CO 2 molecules on the CTS/GO/ZnO composite’s surface. Finally, a renewability study was conducted and a minor loss in the CO 2 adsorption efficiency of about 4.35% was obtained after ten cycles, demonstrating the resulting adsorbent has good performance and robustness for industrial CO 2 capture purposes.