Table 3.

Kinetics constant values of Cd²⁺ adsorption by CHAp.

	Co(mg/L)	40	80	120	160	200	240
First order	Qe(exp) (mg/g)	24.500	46.300	74.500	98.400	122.300	183.400
	Qe(cal) (mg/g)	23.621	46.669	75.086	98.002	124.046	201.942
	k1(mins−1)	0.017	0.024	0.027	0.029	0.036	0.036
	R2	0.994	0.995	0.999	0.997	0.998	0.993
	% SSE	0.011	0.002	0.002	0.001	0.004	0.030
Second order	Qe(cal) (mg/g)	32.987	56.705	91.366	116.896	151.544	267.324
	k2× 104(g/mg/min)	6.802	4.824	3.200	2.904	1.831	5.323
	R2	0.991	0.997	0.999	0.999	0.999	0.994
	% SSE	0.104	0.068	0.068	0.057	0.072	0.138
Elovich	α (mg/g/mins)	2.868	2.527	4.284	7.087	6.758	4.891
	β (g/mg)	0.179	0.073	0.045	0.037	0.027	0.013
	R2	0.999	0.998	0.998	0.999	0.998	0.994
Intra particle diffusion	Kp(mg/g/mins1/2)	1.752	3.547	5.798	7.433	9.533	14.891
	C (mg/g)	3.971	3.941	6.631	11.428	10.511	0.742
	R2	0.990	0.995	0.992	0.992	0.992	0.994