Synthesis of α-MnO₂ Nanomaterial from a Precursor γ-MnO₂: Characterization and Comparative Adsorption of Pb(II) and Fe(III)

Table 2

Equilibrium isotherm parameters.

Isotherm	Nonlinear forms	Isotherm parameters
			Pb(II)	Fe(III)
Langmuir			0.3340	0.135
		(mg/g)	124.9	30.83
		RMSE	3.529	1.504
			0.9109	0.9042
			0.6618	0.7603
		(at the lowest )	0.0291	0.0689
		(at the highest )	5.9510^−3	0.0146
Freundlich			0.1115	0.2033
			74.76	11.52
		RMSE	1.493	0.695
			0.9840	0.9795
			0.1148	0.1296
Sips			6.75	11.84
			−0.9142	0.1986
			0.0070	0.3442
		RMSE	1.4689	0.6272
			0.9846	0.9833
			0.1133	0.1122

: adsorption capacity at equilibrium (mg/g); : maximum adsorption capacity (mg/g); : equilibrium concentration (mg/L); : Langmuir constant; : Freundlich constant; : adsorption intensity; : Sips constant; : Sips isotherm model constant (L/mg); : Sips isotherm model exponent; : correlation coefficient; RMSE: root mean square error; : nonlinear chi-square test.