The determinants of divalent/monovalent selectivity in anion exchangers

摘要: Abstract This research demonstrates that it is the distance of fixed-charge separation in resin which primary determinant divalent/monovalent selectivity. Anion resins, particularly acrylics and epoxies, with closely spaced N-containing (amine) functional groups are inherently divalent-ion selective. because uptake a divalent anion, e.g. sulfate, requires presence two closely-spaced positive charges. Results from this study 30 commercially-available, strong- weak-base, anion resins indicate order to bring charges into close proximity within one can: (1) incorporate amine polymer chains as opposed having them pendant on chains; (2) minimize size number organic (“R”) attached N atom, i.e., amine; (3) maximize flexibility, its ability reorient satisfy counterions, by minimizing degree crosslinking. The distance-of-charge-separation theory not restricted exchangers but also applies cation polyvalent ions general.