EXAFS investigation of Ni(Ⅱ) sorption at the palygorskite-solution interface: New insights into surface-induced precipitation phenomena

Sorption reactions at the mineral/water interface control the fate and transport of trace metals in aqueous geochemical environments. While surface complexation theory is well established, understanding of surface induced precipitation at mineral/water interfaces is still limited. In this research, we employed a combination of macroscopic batch sorption studies, transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and extended X-ray absorption fine structure (EXAFS) spectroscopy to elucidate the sorption mechanisms of nickel (Ni) at palygorskite/solution interfaces. Compared to extensive studies focused on oxides and layer-structured clay minerals, research on chain-type clay minerals (e.g., palygorskite and sepiolite) is sparse. Thus, novel investigations using chain-type clay minerals can provide new insights into the metal sequestration mechanisms and improve equilibrium modeling. In this work, temperature-dependent kinetic experiments demonstrated that t