Competitive Adsorption of Metals onto Magnetic Graphene Oxide: Comparison with Other Carbonaceous Adsorbents

Table 1

Isotherm model parameters of the metal adsorption on the magnetic GO.

System	Metals	pH	Langmuir			Freundlich
			Single metal	Cu(II)	4.0	6.24 ± 0.21^e	0.13 ± 0.01^e	0.998	0.96 ± 0.08^e	0.55 ± 0.03^e	0.992
Pb(II)	15.48 ± 0.95	0.63 ± 0.17		0.981		5.91 ± 0.29	0.37 ± 0.02	0.991
Cd(II)	1.28 ± 0.03	0.14 ± 0.01		0.999		0.21 ± 0.02	0.52 ± 0.04	0.985
Cu(II)	6.0	23.09 ± 1.45		0.59 ± 0.14	0.987	8.59 ± 0.42	0.39 ± 0.03	0.993
Pb(II)		38.50 ± 3.16		4.62 ± 1.72	0.963	27.97 ± 1.28	0.31 ± 0.04	0.967
Cd(II)		4.41 ± 0.19		0.64 ± 0.12	0.981	1.89 ± 0.29	0.29 ± 0.07	0.856
Cu(II)	7.0	59.44 ± 3.64		3.47 ± 0.54	0.991	48.43 ± 1.91	0.46 ± 0.04	0.982
Pb(II)		81.49 ± 9.94		8.41 ± 1.97	0.992	151.17 ± 31.26	0.63 ± 0.09	0.96
Cd(II)		9.92 ± 0.55		0.69 ± 0.18	0.974	4.18 ± 0.59	0.31 ± 0.06	0.899
Multimetal	Cu(II)	4.0	4.33 ± 0.08	0.16 ± 0.01	0.999	0.77 ± 0.10	0.53 ± 0.05	0.977
	Pb(II)		10.27 ± 0.72	0.73 ± 0.25	0.967	4.41 ± 0.39	0.32 ± 0.04	0.964
	Cd(II)		4.59 ± 0.15	0.11 ± 0.01	0.999	0.58 ± 0.07	0.60 ± 0.05	0.984
	Cu(II)	6.0	18.37 ± 1.07	1.36 ± 0.44	0.975	9.36 ± 0.87	0.30 ± 0.05	0.945
	Pb(II)		27.71 ± 1.19	7.05 ± 2.00	0.980	20.45 ± 1.18	0.22 ± 0.04	0.942
	Cd(II)		5.34 ± 0.21	0.24 ± 0.03	0.996	1.26 ± 0.08	0.47 ± 0.03	0.992
	Cu(II)	7.0	46.77 ± 0.96	4.04 ± 0.26	0.998	36.13 ± 2.07	0.39 ± 0.06	0.951
	Pb(II)		43.03 ± 4.83	64.84 ± 33.86	0.911	50.63 ± 2.07	0.17 ± 0.02	0.981
	Cd(II)		6.78 ± 0.32	0.98 ± 0.24	0.976	3.12 ± 0.21	0.31 ± 0.03	0.975

Maximum adsorption capacity estimated by Langmuir isotherm model (mg g⁻¹).
^bAdsorption affinity estimated by Langmuir isotherm model (L mg⁻¹).
^cFreundlich model capacity ((mg/g) ).
^dFreundlich model site heterogeneity factor (dimensionless).
^eStandard errors.