20.500.12556/RUL-177846 Role of ion size and hydration in competitive adsorption of alkaline earth metals on TiO$_2$ nanoparticles experimental and molecular dynamics insights Interactions between alkaline earth metal cations (M$^{2+}$) and titanium dioxide nanoparticles (TiNPs) critically influence the TiNP surface charge and colloidal stability in biological and environmental systems. Here, we systematically investigate how the cation size, hydration, and concentration affect the interfacial adsorption of Mg$^{2+}$, Ca$^{2+}$, Sr$^{2+}$, and Ba$^{2+}$ on TiNPs. X-ray photoelectron spectroscopy and transmission electron microscopy provide direct evidence of cation adsorption on the TiNP surface and reveal ion-specific differences in binding extent and distribution. Zeta potential measurements across a broad pH and concentration range further demonstrate that adsorption increases with cation molar mass and leads to pronounced overcharging of the TiNP surface─an effect that is strongly ion-specific and concentration-dependent. To interpret these experimental findings at the molecular level, molecular dynamics simulations were used to identify binding sites, compute potential of mean force (PMF) profiles, and estimate adsorption free energies, providing insight into ion-specific cation–surface interactions. We find that elevated concentrations of background monovalent salt significantly reduce the level of M$^{2+}$ adsorption, highlighting the importance of competitive adsorption at the nanoparticle–water interface. These results elucidate key factors governing TiNP surface chemistry in complex aqueous environments and inform the design of nanomaterials for biological and ecological applications. adsorption cations anions TiO2 oxides suspensions ions true false true Angleški jezik Ni določen Članek v reviji 2026-01-09 13:30:46 2026-01-09 13:30:47 2026-01-14 04:26:30 0000-00-00 00:00:00 2025 0 0 Str. 62563−62575 iss. 51 Vol. 10 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 544 2470-1343 10.1021/acsomega.5c06067 264131843 role-of-ion-size-and-hydration-in-competitive-adsorption-of-alkaline-earth-metals-on-tio2-nanoparticles-experimental.pdf role-of-ion-size-and-hydration-in-competitive-adsorption-of-alkaline-earth-metals-on-tio2-nanoparticles-experimental.pdf 1 61CD60AC447B59B281AB85EC145AC339 ba1410a55288f51e719245cd9892f762c725f9fcaf03a0dd734ce0371497f51d cef13cc0-f055-11f0-bf92-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=225328 https://pubs.acs.org/doi/10.1021/acsomega.5c06067 1 04a17d3f-ed57-11f0-bf92-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=225207 Fakulteta za kemijo in kemijsko tehnologijo Zdravstvena fakulteta 0 0 0