With high porosity and being one of the most abundant clay minerals, dried kaolinite may\nbe an excellent adsorbent to remove ammonia gas (NH3). Here, the plane wave pseudopotential\nmethod based on density functional theory (DFT) was used to explore the mechanism of ammonia\ngas adsorption on the dried kaolinite, the Mulliken electric charge, and the partial density of states of\natoms of the NH3/kaolinite (001) system. NH3 adsorption on kaolinite can happen in three different\ntype adsorption positions: â??topâ?, â??bridgeâ? and â??hollowâ?. The â??hollowâ? position is enclosed by two\n\"upright\" hydroxyl groups perpendicular to the (001) surface of kaolinite and a \"lying\" hydroxyl\ngroup parallel to the surface. At this position, the adsorption is the most stable and has the highest\nadsorption energy. The nitrogen atom of the NH3 molecule bonds with the hydrogen atom in the\n\"upright\" hydroxyl group on the (001) surface and its hydrogen atom forms HN . . . O hydrogen bond\nwith oxygen atom in the \"lying\" hydroxyl group, which leads to the NH3 stably adsorbed on kaolinite\n(001) surface. A small part of electrons transfer between NH3 molecules and kaolinite creates weakly\nelectrostatic adsorption between them.
Loading....