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

Table 2

Evaluated parameters of pseudo-first-order and pseudo-second-order for Cd (II) and Cr (VI) metal ion biosorption onto ATK and UTK.

Model	Adsorbent	qe (mg/g)	k1 (min^−1)	R^2
Pseudo-first-order	ATK for Cd^2+	4.1120	0.018	0.9501
	UTK for Cd^2+	3.9737	0.0184	0.9244
	ATK for Cr^6+	5.1161	0.0202	0.7555
	UTK for Cr^6+	1.9527	0.0101	0.7635
		qe (mg/g)	k2 (g/mg min)	R^2
Pseudo-second-order	ATK for Cd^2+	1.45	2.303	1
	UTK for Cd^2+	1.453	4.609	1
	ATK for Cr^6+	0.034	6.909	1
	UTK for Cr^6+	1.345	9.212	1