Table 2.

Isotherm parameters for Pb(II) removal by PAC@Fe₃O₄ at 323, 313, and 303 K.

Model	Parameters	Pb (II)
Langmuir		323 K	313 K	303 K
	qm (mg g−1)	314.47	239.34	100.79
	KL (L mg−1)	0.121	0.016	0.003
	R 2	0.99	0.99	0.99
	χ 2	0.10	0.31	0.47
Freundlich	n	1.58	1.14	1.02
	KF (mg g−1) (dm3/g)n	13.14	4.48	2.22
	R 2	0.99	0.98	0.98
	χ 2	2.59	3.69	0.57
Temkin	AT (L mg−1)	1.39	0.42	0.28
	bT (J mol−1)	131.96	105.32	118.23
	R 2	0.98	0.97	0.97
	χ 2	3.72	5.64	4.53
Redlich‒Peterson	g	0.96	5.31	5.81
	KR (L g−1)	12.50	3.48	2.10
	aR (L mg−1)	0.14	4.80	1.02
	R 2	0.99	0.99	0.99
	χ 2	0.14	0.58	0.44