Figure 2

Effect of competing ions on the Sr²⁺ sorption capacity of HAPs. The change in A _eff for DEF-HAP (dark gray) and ST-HAP (light gray) as a function of the concentration (mmol/L) of (a) Mg²⁺ ([Mg²⁺]) and (b) Ca²⁺ ([Ca²⁺]) is shown. The dashed and solid lines represent the approximate average [Mg²⁺] and [Ca²⁺] in seawater¹⁴ (52 mmol/L for Mg²⁺ and 9.4 mmol/L for Ca²⁺) and in FNPP ground water¹⁵ (0.86 mmol/L for Mg²⁺ and 0.70 mmol/L for Ca²⁺), respectively. The hydrated ionic radii of Mg²⁺ and Ca²⁺ are 0.6 Å and 1.0 Å, respectively. α is the ionic hydrated radius (Å).