Table 8. Pseudo-Primary and Pseudo-Second-Order Kinetic Model Fitting Parameters of Cr(VI) Adsorption.

	quasi-first-order dynamic model			quasi-second-order dynamic model
adsorbent	k1 (min–1)	R2	Qe (mg/g)	k2 (g/(mg min))	R2	Qe (mg/g)
MWCNTs-3	0.01078	0.9938	2.2897 ± 0.75%	0.01378	0.9999	26.1780 ± 0.75%
MWCNTs-OH-3	0.00961	0.9904	2.6154 ± 0.75%	0.008095	0.9997	28.7356 ± 0.75%
MWCNTs-COOH-3	0.00894	0.8592	2.3573 ± 0.75%	0.009111	0.9996	31.5457 ± 0.75%