Effects of Cu(II) on the Adsorption Behaviors of Cr(III) and Cr(VI) onto Kaolin

Table 1

Comparison of rate constants calculated based on pseudofirst-order and pseudosecond-order models.

Adsorbed solution	(mg·g^−1)	Pseudofirst-order kinetic model			Pseudosecond-order kinetic model
		(mg·g^−1)	(min^−1)	R^2	(mg·g^−1)	(g·mg^−1·min^−1)	R^2
Cr(III)	0.898	0.920	0.042	0.993	1.120	0.042	1.000
Cr(III)-Cu	1.030	0.978	0.130	0.967	1.049	0.209	0.963
Cr(VI)	0.853	0.865	0.051	0.993	1.040	0.052	0.976
Cr(VI)-Cu	0.131	0.132	0.043	0.990	0.162	0.270	0.981