Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions

Table 2 Kinetic parameters for Cu(II), Zn(II), Cd(II), and Pb(II) ions sorption on ST20

Model	Parameter	Cu(II)	Zn(II)	Cd(II)	Pb(II)
PFO	q _1,cal	8.85	7.28	4.91	8.84
	k ₁	0.067	0.041	0.053	0.032
	t _1/2	0.008	0.012	0.018	0.019
	R ²	0.9321	0.9970	0.8691	0.8219
PSO	q _2,cal	9.26	12.10	10.71	15.62
	k ₂	0.039	0.030	0.060	0.034
	h	3.365	4.334	6.860	8.406
	t _1/2	0.034	0.024	0.016	0.022
	R ²	0.9993	0.9990	0.9995	0.9999
IPD	k_i1 (mg g⁻¹ min^−1/2)	1.29	1.67	1.65	1.27
	C ₁	4.92	7.66	6.74	8.30
	R ² ₁	0.9008	0.9614	0.9790	0.8754
	k_i2 (mg g⁻¹ min^−1/2)	0. 82	0.20	0.26	0.35
	C ₂	8.14	9.54	10.86	12.51
	R ² ₂	0.9337	0.9179	0.9348	0.8393
	k_i3 (mg g⁻¹ min^−1/2)	0.23	0.13	0.08	0.09
	C ₃	7.94	9.02	12.06	14.20
	R ² ₃	0.9983	0.9696	0.9937	0.9204
EM	a	17.23	10.24	18.65	18.64
	b	0.57	1.47	1.30	0.77
	R ²	0.9494	0.9437	0.9311	0.8629

PFO pseudo first order, PSO pseudo second order, IPD intraparticle diffusion model, EM Elovich model