Exploring the potential of KOH-modified MXene (Ti3C2Tx) as a promising adsorbent for enhanced CO2 capture

Titanium carbide MXenes (Ti 3 C 2 T x ), synthesized using two different methods, along with KOH-modified Ti 3 C 2 T x samples synthesized using LiF/HCl etching solution as the optimal synthesis method, were investigated as potential CO 2 adsorbents. Structural analyses using XRD, FTIR, BET, and SEM-EDX techniques indicate that the modification of Ti 3 C 2 T x with KOH enhances surface active sites and alters the structure of the MXene layers, resulting in enhanced layer separation and the formation of larger pores. The response surface methodology (RSM) using a central composite design was applied to optimize adsorption parameters, indicating that temperature, pressure, and KOH weight percentage are key variables affecting adsorption capacity. Under optimal conditions of 25 °C, 5.62 bar, and 21.46 wt% KOH, an adsorption capacity of 7.67 mmol/g was achieved. The Sips isotherm model exhibited the most accurate correlation with the experimental adsorption data, suggesting a combination of multilayer and monolayer CO 2 adsorption on a heterogeneous surface. The kinetic findings indicated that the fractional-order kinetic model most accurately represents the data, and the adsorption process is affected by intricate interactions involving multiple pathways. The thermodynamic analysis of adsorption validated the exothermic and spontaneous characteristics of the process. The optimal Ti 3 C 2 T x -KOH20 sample, due to its structural and functional enhancements, demonstrated the highest adsorption capacity among all samples. It also maintained 94.62% of its initial adsorption capacity after multiple cyclic regenerations. This result demonstrates its stability and reproducibility under various operational conditions, indicating its potential for industrial and environmental applications.