Table 3.

Isotherm parameters calculated from linear regression for 18β-glycyrrhetinic acid adsorption onto mesoporous silica functionalized with various amine groups.

Adsorption model	Parameter	Adsorbent
		SBA-15-AP	SBA-15-MAP	SBA-15-DMAP	SBA-15-AEAP
Langmuir	QL(max) (mg/g)	169.5	151.5	61.0	178.6
	KL (dm3/mg)	2.745 × 10−3	2.794 × 10−3	3.072 × 10−4	2.384 × 10−3
	r 2	0.9992	0.9970	0.9903	0.9993
Freundlich	KF (mg1−1/ndm3/n/g)	2.973	2.413	2.923 × 10−2	2.868
	nF	1.948	1.879	1.126	1.938
	r 2	0.9440	0.9680	0.9941	0.9422
Redlich−Peterson	KRP (dm3/g)	0.488	0.479	−	0.441
	aRP (dm3β/mgβ)	6.698 × 10−3	1.581 × 10−2	−	4.144 × 10−3
	β	0.883	0.778	−	0.931
	r 2	0.9993	0.9978	−	0.9949
Temkin	KT (dm3/mg)	3.765 × 10−2	3.032 × 10−2	4.372 × 10−3	3.571 × 10−2
	bT (J g/mol mg)	72.74	72.42	157.1	72.93
	r 2	0.9839	0.9659	0.8247	0.9883
Dubinin–Radushkevich	QDR(max) (mg/g)	286.3	272.9	98.4	284.6
	KDR (mol2/J2)	8.110 × 10−9	8.369 × 10−9	1.616 × 10−8	8.209 × 10−9
	EDR (kJ/mol)	7.85	7.73	5.56	7.80
	r 2	0.9901	0.9971	0.9703	0.9891
Dubinin–Astakhov	QDA(max) (mg/g)	210.4	237.9	−	203.0
	KDA (molnDA/JnDA)	5.462 × 10−12	6.442 × 10−10	−	2.030 × 10−12
	nDA	2.733	2.257	−	2.834
	EDA (kJ/mol)	9.34	8.35	−	9.45
	r 2	0.9988	0.9982	−	0.9996