Utilization of Macadamia Nutshell Residue for the Synthesis of Magnetic Activated Carbon toward Zinc (II) Ion Removal

Table 1

Kinetics model parameters for the adsorption of Zn²⁺ ion by the ACP/Fe₃O₄ composite.

Models	Kinetics model parameters and regression coefficients
Pseudo-first-order	k1 (min^−1)	qe (mg g^−1)	R^2
	0.030	19.50	0.970
Pseudo-second-order	k2 (g mg^−1 min^−1)	qe (mg g^−1)	R^2
	0.0081	22.73	0.993
Elovich	α (mg g^−1 min^−1)	β (mg g^−1)	R^2
	2.76	0.055	0.998
Intraparticle diffusion	ki (mg g min^−0.5)	C	R^2
	1.07	11.32	0.824