Table 6.

Isotherm parameters calculated from nonlinear fitting analysis for 18β-glycyrrhetinic acid adsorption onto non-porous silica functionalized with various amine groups.

Adsorption model	Parameter	Adsorbent
		Aer-AP	Aer-MAP	Aer-DMAP	Aer-AEAP
Langmuir	QL(max) (mg/g)	99.6	98.1	−	104.1
	KL (dm3/mg)	2.191 × 10−3	1.835 × 10−3	−	1.468 × 10−3
	MPSD	7.47	11.28	−	10.26
Freundlich	KF (mg1−1/ndm3/n/g)	2.011	1.705	1.380 × 10−2	1.295
	nF	2.125	2.052	1.081	1.908
	MPSD	17.73	13.93	15.21	13.33
Redlich−Peterson	KRP (dm3/g)	0.269	0.269	3.910	0.219
	aRP (dm3β/mgβ)	8.902 × 10−3	1.916 × 10−2	282.5	1.629 × 10−2
	β	0.853	0.762	0.075	0.751
	MPSD	3.59	4.65	16.04	2.82
Temkin	KT (dm3/mg)	4.093 × 10−2	3.689 × 10−2	−	3.117 × 10−2
	bT (J g/mol mg)	148.7	154.9	−	150.1
	MPSD	14.43	17.03	−	18.60
Dubinin–Radushkevich	QDR(max) (mg/g)	144.2	141.4	64.0	149.6
	KDR (mol2/J2)	7.806 × 10−9	8.159 × 10−9	1.740 × 10−8	8.825 × 10−9
	EDR (kJ/mol)	8.00	7.83	5.36	7.53
	MPSD	6.31	3.70	28.55	2.29
Dubinin–Astakhov	QDA(max) (mg/g)	118.2	133.7	-	144.2
	KDA (molnDA/JnDA)	4.282 × 10−11	2.628 × 10−9	-	4.363 × 10−9
	nDA	2.525	2.114	-	2.071
	EDA (kJ/mol)	9.03	8.10	-	7.70
	MPSD	3.03	3.65	-	2.27