Figure 21.

Separation factor β_i:j calculated using eq 7 in MCDI, CDI with porous carbons, and CDI with intercalation or conversion electrodes for pairs of competing anions and cations. β_i:j > 1 implies selectivity toward ion i, β_i:j < 1 implies selectivity toward ion j, and β_i:j = 1 (dashed line) corresponds to no selectivity. Competing monovalent ions (ion valence 1:1) typically display β_i:j between 1 and 10. Competing divalent and monovalent ions (ion valence 2:1) display a wider range of β_i:j, typically between 0.01 and 24. References for valence 1:1 ion pairs in alphabetical order: Br^–:Cl^–,⁷³⁵ Br^–:F^–,⁷³⁵ Cl^–:F^–,^683,735 K⁺:Li⁺,^688,690 K⁺:Na⁺,^{712,728,735,739} Na⁺:Li⁺,⁶⁸⁸ NH₄⁺:Na⁺,⁷⁴⁰ NO₃:Br^–,⁷³⁵ NO₃^–:Cl^– (MCDI,^678,680 CDI^{651,709,734,735}), and NO₃:F^–.^709,735 References for valence 2:1 ion pairs: Ca²⁺:Li⁺,⁶⁸⁸ Ca²⁺:Na⁺ (MCDI,⁷⁴¹ CDI,^{647,648,712,723} intercalation or conversion^742,743) Mg²⁺:Li⁺,^688,689,744 Mg²⁺:Na⁺,⁷⁴² SO₄^2–:Cl^–,^734,745,746 and SO₄:NO₃^–.⁷⁰⁹