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

Figure 3

Amount of REEs adsorbed on synthetic hydroxyapatite (𝑞_𝑡) and fitting of the data to the pseudo-second-order model (𝑡/𝑞_𝑡) both of them as a function of contact time. [La(III)]_i=5.7×10⁻⁵ mol/L; [Eu(III)]_i=6.5×10⁻⁵ mol/L. The equations of the lines are: 𝑡/𝑞_𝑡=4.0+1.88𝑡 (𝑅²=0.9999) for La(III) and 𝑡/𝑞_𝑡=1.02+1.60𝑡 (𝑅²=0.9999) for Eu(III).