Adsorption Behaviour of La(III) and Eu(III) Ions from Aqueous Solutions by Hydroxyapatite: Kinetic, Isotherm, and Thermodynamic Studies

Figure 5

Isotherms of Freundlich model with 1/𝑛>1 for REEs on synthetic hydroxyapatite. The equations of the lines are: log 𝑞_𝑒=2.3 log 𝐶_𝑒+0.07 (𝑅²=0.995) for [La(III)]: 1.7×10⁻⁴–3.6×10⁻⁴ mol/L (rhombus); log 𝑞_𝑒=4.7 log 𝐶_𝑒−0.9 (𝑅²=0.96) for [La(III)]: 3.3×10⁻⁵–2.2×10⁻⁴ mol/L (triangles); log 𝑞_𝑒=1.8 log 𝐶_𝑒+0.2 (𝑅²=0.99) for [Eu(III)]: 1.9×10⁻⁴–4×10⁻⁴ mol/L (circles).