Table 2.

The kinetic parameters of adsorption of Pb(II) onto SPEN-CTAB-0%, SPEN-CTAB-5% and SPEN-CTAB-15%.

Membrane	Parameters	SPEN-CTAB-0%	SPEN-CTAB-5%	SPEN-CTAB-15%
Pseudo-first-order	k1 (min−1)	0.0278	0.0404	0.0398
	qe (cal.) (mg/g)	12.811	12.678	11.274
	qe (exp.) (mg/g)	183.60	161.73	127.43
	R 2	0.8703	0.8320	0.6967
Pseudo-second-order	k2 (g/mg·min)	0.00037	0.00036	0.0012
	qe (cal.) (mg/g)	202.43	185.53	134.05
	qe (exp.) (mg/g)	183.60	161.73	127.43
	R 2	0.9911	0.9693	0.9978
Intraparticle diffusion	k i1	33.697	28.316	24.236
	C	2.4810	−10.281	−1.170
	R 1 2	0.9879	0.7428	0.9948
	k i2	6.1267	2.1267	0.7810
	C	115.84	137.61	117.76
	R 2 2	0.9682	0.8814	0.5995