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

Table 4

Changes of enthalpy, entropy, and Gibbs-free energy for the adsorption of lanthanum and europium on hydroxyapatite.

REE	Δ𝐻^∘ (kJ/mol)	Δ𝑆^∘ (kJ/mol K)	T, (K)	Δ𝐺^∘ (kJ/mol)
La(III)	5.9	0.08	293	−16.2
			303	−17.0
			313	−17.8
			323	−18.5
Eu(III)	34.1	0.17	293	−15.2
			303	−16.9
			313	−18.5
			323	−20.2