Table 3.

Calculated constants of the kinetic models for Cr (VI) adsorption on Sambucus nigra L. based on linear and non-linear models

Kinetic models	Parameters	Values
Linear model
Pseudo-first order	K1 (1/min)	0.003
	qe (mg/g)	4.869
	R2	0.848
Pseudo-second order	K2 (g/mg min)	0.029
	qe (mg/g)	2.412
	qe (projected) (mg/g)	1.353
	R2	0.996
Non-linear model
Pseudo-first order	K1 (1/min)	3.135
	qe (mg/g)	4.650
	R2	0.864
Pseudo-second order	K2 (g/mg min)	2.847
	qe (mg/g)	2.350
	qe (projected) (mg/g)	1.353
	R2	0.974
Intraparticle diffusion model	K1 (1/min) R2	0.745 0.928