Dft Studies On The Interaction Of Fe2+ /Fe3o4 (111) And Oh-/Fe3o4 (111) During The Adsorption Process In The Steam Generators Of Nuclear Power Plants

Based on the fouling problem on the outer surface of the steam generator tube in the secondary circuit condition of pressurized water reactors, the density functional theory was used to calculate the adsorption characteristics of Fe2+, OH- on Fe3O4 surface. Eight kinds of highly symmetric adsorption configurations of Fe2+ and OH- on /Fe3O4 (1 1 1) surface under two kinds of Fe-tet1- and Fe-oct2-terminated surfaces were established. Meantime, the interaction mechanisms and electronic structures of Fe2+/Fe3O4 (1 1 1), OH/Fe3O4 (1 1 1) before and after the adsorption process were studied. The results demonstrated that the most stable adsorption site of Fe2+/Fe3O4 (1 1 1) is the Fe3O4 (111) tet-b configuration. After Fe2+ adsorbed on Fe3O4 (111) tet-b sites, the lengths of Fe-Fe and Fe-O bonds and the Fe-Fe-O angle changed. The parallel and vertical directions of top atoms in /Fe3O4(1 1 1) surface changed and the shift of topmost atoms was the largest, indicating that the Fe3O4 crystal lattice parameters can be affected by the Fe2+ adsorption. The charge population, density of states, and electron local function results indicated that there were 0.5e to 0.81e electron transfer between Fe2+ and Fe3O4 (1 1 1). The electron transfer of OH-/Fe3O4 (111) oct-O-h is from 0.18e to 0.63e. Both of the Fe2+ and OH- can form the chemical bond on the Fe3O4 (1 1 1) surface. The results illustrate the nucleation and agglomeration of Fe3O4 scale and provide the foundation for the further research on Fe3O4 scale deposition.