(253l) First Principles Computational Study on Adsorption of Organic Methyl Iodide in Triethylenediamine Impregnated Activated Carbon

We study removal of gas-phase organic iodine (CH₃I), which is one of the toxic chemical generated in nuclear power plant operation or accidents, via adsorption in triethylenediamine (TEDA) impregnated activated carbon (AC). We apply first principles density functional theory (DFT) calculations to understand how experimentally observed quaternary ammonium salts form in the surface. It is propose that the adsorption energy of a CH₃I shows substantial heterogeneity as function of varying the adsorption sites, porosity and H₂O environment. Most importantly, it is clearly shown by first principles calculated free energy diagrams for the adsorption processes that TEDA not only helps in reducing the activation barrier of the dissociation of CH₃I but also attracts H₂O molecules freeing the porous AC surface from poisoning by humidity and enhancing removal efficiency of the CH₃I. Our computational study enables to unveil detailed chemical process and thus, can open new ways to design highly functional AC in removing environmentally and biologically hazardous materials.