Table 1.

Estimated kinetic parameters of the two adsorption models for methylene blue (MB) and Congo red (CR).

Sample		MB Concentration (mg L−1)			CR Concentration (mg L−1)
GnP	Param.	10	250	500	100	600	2000
pseudo-first order	qe (mg g−1)	22.2	544.2	496.7	167.0	1113.7	1383.5
	k1 (min−1)	1.192	0.170	0.282	0.040	0.049	0.059
	R2	0.927	0.955	0.856	0.971	0.912	0.960
pseudo-second order	qe (mg g−1)	23.2	578.3	515.9	213.2	1223.5	1510.4
	k2 (g mg−1 min−1)	7.1 × 10−2	4.7 × 10−4	1.1 × 10−3	1.7 × 10−4	5.9 × 10−5	6.1 × 10−5
	v0 (mg g−1 min−1)	38.0	157.1	282.2	7.76	87.9	138.4
	R 2	0.966	0.985	0.937	0.968	0.954	0.981
CNF
pseudo-first order	qe (mg g−1)	37.8	831.0	1140.0	20.7	92.5	173.4
	k1 (min−1)	0.232	0.198	0.145	0.011	0.012	0.153
	R2	0.986	0.972	0.933	0.982	0.942	0.960
pseudo-second order	qe (mg g−1)	40.6	874.8	1225.0	33.0	114.5	182.4
	k2 (g mg−1 min−1)	8.9 × 10−3	3.8 × 10−4	1.9 × 10−4	2.2 × 10−4	1.20 × 10−4	1.2 × 10−3
	v0 (mg g−1 min−1)	14.7	294.0	278.1	0.241	1.57	38.6
	R 2	0.999	0.994	0.976	0.978	0.948	0.952
CNF–GnP 3:1
pseudo-first order	qe (mg g−1)	35.2	767.2	1114.0	37.9	321.4	538.8
	k1 (min−1)	0.210	0.112	0.063	0.128	0.022	0.024
	R2	0.944	0.961	0.951	0.915	0.931	0.992
pseudo-second order	qe (mg g−1)	37.2	834.3	1264.5	44.1	379.4	648.5
	k2 (g mg−1 min−1)	1.0 × 10−2	2.0 × 10−4	6.3 × 10−5	3.0 × 10−3	7.07 × 10−5	4.0 × 10−5
	v0 (mg g−1 min−1)	14.1	137.2	100.2	5.92	10.2	16.9
	R 2	0.978	0.977	0.910	0.940	0.955	0.972