Table 5.

Adsorption kinetics for adsorption of Cu (II) onto the two floating plant species.

	Model	Adsorbent	Sorbent	Parameter
			Cu(II) Concentration (mg/L)	qe,exp (mg g−1)	qe,cal (mg g−1)		k1 (day−1)		R2
(a)	Pseudo-first-order	Azolla filiculoides	0.25	0.2297	0.5049		−0.1299		0.3309
			0.5	0.8912	0.9480		−0.0101		0.3309
			0.75	1.1676	0.4305		−0.1292		0.1161
			1	1.6819	0.2202		−0.1654		0.0675
		Lemna minor	0.25	0.2494	0.2121		−0.2639		0.4903
			0.5	1.4020	0.6001		0.0226		0.0073
			0.75	2.4328	1.2900		0.0523		0.1014
			1	4.0473	3.8353		0.4470		0.7581
(b)	Model	Adsorbent	Sorbent	Parameter
			Cu(II) Concentration (mg/L)	qe,exp (mg g−1)	qe,cal (mg g−1)		k2 (g mg−1 day)		R2
	Pseudo-second-order	Azolla filiculoides	0.25	0.230	0.2297		3.7894 × 1015		1
			0.5	0.891	0.819		-		1
			0.75	1.168	1.1733		27.6204		0.9999
			1	1.682	1.6969		9.9506		0.9996
		Lemna minor	0.25	0.249	0.2879		14.0513		0.9648
			0.5	1.402	1.0385		−5.3286		0.9209
			0.75	2.432	1.5201		−2.5817		0.8822
			1	4.047	4.6577		0.1259		0.8191
(c)	Model	Adsorbent	Sorbent	Parameter
			Cu(II) Concentration (mg/L)	ki (mg g−1 min−1)		I (mg g−1)		R2
	Intra-particle diffusion	Azolla filiculoides	0.25	0.077		0.0714		0.6114
			0.5	0.2987		0.2771		0.6114
			0.75	0.4006		0.3319		0.6619
			1	0.5856		0.4462		0.696
		Lemna minor	0.25	0.0843		0.0314		0.8137
			0.5	0.3823		0.2732		0.5774
			0.75	0.6189		0.4506		0.5302
			1	1.6135		−0.0762		0.9455