Orange peel as low-cost adsorbent in the elimination of Cd(II) ion: kinetics, isotherm, thermodynamic and optimization evaluations

Bioresources and Bioprocessing

Table 1 Kinetic data values for the adsorption of cadmium by OP

	C_o (mg/L)	50	100	150	200	250
First order	Q_e(exp) (mg/g)	26.636	45.921	77.383	93.386	122.061
	Q_e(cal) (mg/g)	26.450	43.700	78.250	96.200	135.950
	k₁ (min⁻¹)	0.118	0.134	0.076	0.124	0.129
	R²	0.987	0.988	0.995	0.964	0.989
	% SSE	0.002	0.001	0.003	0.003	0.027
Second order	Q_e(cal) (mg/g)	28.725	49.780	85.362	101.530	132.428
	k₂ (g/mg/min)	0.206	0.104	0.201	0.021	0.111
	R²	0.988	0.997	0.995	0.988	0.997
	% SSE	0.006	0.004	0.001	0.002	0.001
Elovich	α (mg/g/min)	32.443	56.815	30.945	98.310	100.000
	β (g/mg)	0.251	0.143	0.071	0.069	0.050
	R²	0.994	0.991	0.996	0.996	0.958
Intraparticle diffusion	K_id (mg/g/min^1/2)	1.633	2.943	5.177	5.966	7.763
	C_i (mg/g)	9.192	15.517	20.807	31.046	41.320
	R²	0.957	0.959	0.977	0.980	0.978