Adsorption of Cu(II) and Zn(II) onto Activated Carbon from Oil Palm Empty Fruit Bunch Prepared by Two-Step Acid Treatment and Microwave-Assisted Pyrolysis

Table 5

Isotherm parameters for the adsorption of Cu(II) and Zn(II) onto EFB and 2ACEFB.

Isotherm model	Parameters	Adsorbent-adsorbate
		EFB-Cu	2ACEFB-Cu	EFB-Zn	2ACEFB-Zn
Two-parameter model
Langmuir		0.052; 20.02; 0.997; 6.11	0.038; 44.29; 0.996; 3.80	0.036; 17.82; 0.997; 6.28	0.029; 36.43; 0.997; 4.60
Freundlich		2.51; 2.62; 0.929; 20.58	2.58; 1.67; 0.955; 15.35	1.920; 2.55; 0.885; 18.38	1.93; 1.72; 0.929; 16.56
Temkin		315.97; 0.604; 0.984; 11.27	350.21; 0.403; 0.972; 18.65	697.39; 0.825; 0.937; 75.52	757.95; 0.527; 0.964; 48.41
Three-parameter model
Redlich-Peterson		1.009; 0.049; 1.000; 0.977; 2.985; 6.05	1.938; 0.066; 0.9336; 0.998; 1.327; 3.41	0.621; 0.034; 1.000; 0.971; 2.824; 6.41	1.101; 0.031; 1.000; 0.993; 2.651; 4.82
Sips model	MAPE	20.01; 0.040; 1.088; 0.978; 2.918; 7.97	41.66; 0.046; 0.955; 0.998; 1.484; 3.21	17.80; 0.030; 1.053; 0.972; 2.805; 7.57	33.58; 0.022; 1.150; 0.995; 2.294; 7.26
Toth model	M	20.28; 0.053; 0.987; 0.976; 3.016; 6.02	40.67; 0.045; 0.987; 0.997; 1.555; 2.41	18.06; 0.034; 1.000; 0.971; 2.82; 6.41	36.00; 0.031; 1.000; 0.993; 2.66; 4.82