Biosorption Studies of Cd²⁺ and Cr⁶⁺ from Aqueous Solution Using Cola-Nut Leaves as Low-Cost Biosorbent

Table 3

Evaluated parameters of Langmuir, Freundlich, and Temkin isotherms for Cd (II) and Cr (VI) metal ion biosorption onto ATK and UTK.

Model	Biosorbents	Qo (mg/g)	KL (L/mg)	RL	R^2
Langmuir	ATK for Cd^2+	178.57	2.15	0.0046	0.3707
	UTK for Cd^2+	555.56	1.56	0.0064	0.1803
	ATK for Cr^6+	200	16.67	0.000599	0.548
	UTK for Cr^6+	185.19	899.97	0.000011	0.5258
		Kf	N		R^2
Freundlich	ATK for Cd^2+	17.972	0.3749		0.5617
	UTK for Cd^2+	218.85	0.3966		0.6256
	ATK for Cr^6+	13.129	1.5035		0.6477
	UTK for Cr^6+	5.0298	1.058		0.6985
		bT	AT (Lg^−1)	B	R^2
Temkin	ATK for Cd^2+	0.00123	1.219	6784.7	0.855
	UTK for Cd^2+	0.0025	295.35	404.91	0.1299
	ATK for Cr^6+	0.0065	1.10	1280	0.9553
	UTK for Cr^6+	0.0064	6.380	1303.3	0.7828