co-ions

https://doi.org/10.1351/goldbook.C01141
  1. Ions of low relative molecular mass with a charge of the same sign as that of a given colloidal ion.
    Source:
    PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 607 (https://doi.org/10.1351/pac197231040577)
  2. In an ion exchanger, mobile ionic species with a charge of the same sign as the fixed ions.
    Source:
    Orange Book, 2nd ed., p. 88 (http://media.iupac.org/publications/analytical_compendium/)