Effective Carbon Dioxide and Iodine Adsorption in Ionic Liquid Modified Porous Organic Polymers

Abstract

Capturing carbon dioxide (CO₂) and iodine in a safe and affordable way is difficult because of various reasons, including selectivity. In this study, microwave-assisted Friedel-Crafts alkylation of N,N″,N″′-Triphenyl-1,3,5-benzenetriamine (TBT) and pyrrole (Py) using dimethoxymethane as a cross-linker is used to prepare porous organic polymers with and without protic ionic liquid (PIL). The produced polymers are evaluated by ¹³C NMR, FTIR, thermogravimetric analyzer, Brunauer–Emmett–Teller surface analyzer, and XPS. The surface areas of the porous polymers ranged from 18.89 to 41.61 m² g⁻¹. These polymers are also assessed for their gas adsorption, iodine, and methyl iodide adsorption capabilities. At 273 K and 1 atm, the polymer produced with PIL (A6) showed the maximum CO₂ adsorption capacity (1.38 mmol g⁻¹), and affinity (Q_st value of 57 KJ mol⁻¹). The initial slope selectivity of these polymers for CO₂/N₂ is between 93 and 106, and for CO₂/CH₄, it is between 16 and 18 at 273 K. Also, A6 polymer showed a high adsorption capacity of 146 wt.% iodine and 73 wt.% methyl iodides. The XPS analysis revealed a significant interaction between iodine/methyl iodide and the A6 polymer. The results suggest that polymers containing PIL may collect CO₂ and iodine, making them promising environmental remediation materials.