Physicochemical processes

What are the effects of environmental factors on Co speciation at the magnetite surface?

“…The second mechanism differs for R0.1, R0.3 and R0.5, with Q max,L2 values equal to 4.16, 9.48 and 10.51 atoms per nm 2 , respectively. Finally, the third mechanism, which used the Freundlich equation to account for surface precipitation (as it can be seen as a multi-layer formation) [62][63][64] also differs between the three stoichiometries, with n-K F couples leading to an onset of Co(OH) 2 precipitation at [Co] aq = 0.4 mM for R0.1, and approximately 0.1 mM for R0.3 and R0.5. This difference in Co behavior could be explained by the fact that R0.1 magnetite, which has a structure close to that of maghemite, has less Fe on its surface replaced by vacancies, which might limit Co oligomer and precipitate formation on its surface.…”