Table 4.

The kinetic parameters for the adsorption of Pb(II) onto SPEN-CTAB-0%.

C0 (mg/L)	Parameters	50	70	100	150	200
Pseudo-first-order	k1 (min−1)	0.0284	0.0387	0.0450	0.0490	0.0201
	qe (cal.) (mg/g)	13.861	13.730	13.821	13.052	12.174
	qe (exp.) (mg/g)	195.82	196.09	202.99	217.92	246.96
	R 2	0.9370	0.9588	0.9712	0.8994	0.4650
Pseudo-second-order	k2 (g/mg·min)	1.8 × 10−4	3.4 × 10−4	3.8 × 10−4	8.1 × 10−4	1.1 × 10−3
	qe (cal.) (mg/g)	234.74	219.30	225.22	228.83	245.70
	qe (exp.) (mg/g)	195.82	196.09	202.99	217.92	246.96
	R 2	0.9896	0.9975	0.9978	0.9990	0.9951
Intraparticle diffusion	k i1	23.188	28.463	31.556	44.485	55.225
	C	−5.5100	−1.8826	−2.4937	−0.9429	10.448
	R 1 2	0.8930	0.9875	0.9877	0.9967	0.9446
	k i2	8.5084	5.5405	4.7350	2.1192	2.2246
	C	101.91	136.41	153.10	195.22	197.36
	R 2 2	0.9668	0.9819	0.9545	0.9806	0.3939