Isotopic Fractionation of Potassium by Diffusion in Methanol

JN Christensen and AE Hofmann and DJ DePaolo, ACS OMEGA, 4, 9497-9501 (2019).

DOI: 10.1021/acsomega.9b00690

We present the results of experiments involving the isotopic fractionation by diffusion of K+ cations in methanol at 298 K along with supporting molecular dynamic simulations. The experiments, using glass Rayleigh fractionators filled with a methanol solution of KCI, constrain the ratio of the individual diffusivities of K-41 and K-39 (D-41K/D-39K) in methanol, and so the isotopic fractionation of K+ due to diffusion in methanol, to 0.9995 +/- 0.0001. This isotopic fractionation is 25% of the fractionation resulting from K+ diffusion in water. This is consistent with published molecular dynamics simulations indicating greater hydrodynamic coupling between K+ ions and solvating methanol molecules compared to K+ ions and solvating water molecules.

Return to Publications page