Synthesis and performance enhancement of GO/MgO/PEI composite for CO₂ capture: Effects of operating parameters

In this study, a composite of Graphene Oxide, Magnesium Oxide, and Polyethyleneimine (GO/MgO/PEI) was synthesized and utilized as a novel adsorbent for CO2 capture. Material characterization was performed using XRD, FTIR, FE-SEM, TGA, and BET analysis. The composite achieved a maximum CO2 adsorption capacity of 291.70 mg/g at 298 K and 8.7 bar, with an optimal GO-MgO ratio of 1:1 and PEI at 3 wt%. Operating parameters such as temperature, pressure, and PEI concentration were examined and optimized using response surface methodology with a Box–Behnken design (RSM-BBD). Analysis of variance indicated that all input variables significantly affected the CO2 uptake process. The strong correlation between the CO2 uptake process and the model was demonstrated by an R² value of 0.9946. Isotherm and kinetic studies revealed that the Sips and Pseudo second-order models best represented the CO2 adsorption behavior. Furthermore, thermodynamic analysis indicated that the process was exothermic, spontaneous, and physical in nature. Additionally, recyclability tests showed only a small reduction in CO2 adsorption efficiency after 20 cycles, suggesting promising performance for industrial applications. • A novel GO/MgO/PEI composite was synthesized for efficient CO₂ adsorption. • Adsorption capacity: 291.7 mg/g at 298 K, 8.7 bar, with 1:1 GO–MgO and 3 wt% PEI. • RSM-BBD optimization showed strong predictive accuracy with R² = 0.9946. • CO₂ uptake fitted the Sips isotherm and pseudo second-order kinetic model. • Good recyclability with small reduction observed after 20 adsorption cycles.