Intraparticle diffusion parameters for the adsorption of Pb(ii) and Cd(ii).

Metal	C 0 (mg g−1)	k ip1 (mg g−1 min−0.5)	C 1	R 2	k ip2 (mg g−1 min−0.5)	C 2	R 2	k ip3 (mg g−1 min−0.5)	C 3	R 2
Pb	50	5.294	17.91	0.575	0.334	36.04	0.795	0.009	39.529	0.424
	100	103.800	−4.76	0.990	5.672	15.62	0.926	0.391	67.014	0.980
	200	17.463	−9.68	0.999	2.018	57.92	0.914	0.718	67.946	0.999
Cd	50	1.356	16.70	0.909	2.191	15.73	0.847	0.094	29.109	0.995
	100	2.548	30.32	0.854	9.462	−5.45	0.999	0.072	53.207	0.368
	150	6.108	22.78	0.979	8.530	−3.02	0.837	0.928	70.520	0.859