In the above equation (Eq. 2) to derive N water removed from relative change in system volume, N A is the Avogadro constant (N A = 6.023 × 10 Ionization by either monovalent (Na + ) or trivalent (Fe 3+ ) cation species was carried out to neutralize the system. This worked out to be a 150 Na + ions, or 50 Fe 3+ ions. This is approximately a 35.5 mM cation concentration for the monovalent cation, and a lower concentration (11.8 mM) for the trivalent cation.