Journal of Chemistry

Research Article

Potato Peels as an Adsorbent for Heavy Metals from Aqueous Solutions: Eco-Structuring of a Green Adsorbent Operating Plackett–Burman Design

Table 5

General and used linear form equations of the adsorption isotherms with the extracted parameters from Figures 12(a)–12(d) as described [53–55].


Item	Langmuir	Freundlich	Temkin	Dubinin–Radushkevich

General equation

Linear form

Parameters	Region (I): = 0.25 mg/g = −1.386 L/mg = 1.45	= 16.77 L/g = 1.714 = 0.583	= 66 kJ/mole = 1.85 L/g	= 5.689 × 10⁻⁷ M² J² = 0.937 kJ/mole (C_e in mg/L) = 5.00 kJ/mole (C_e in M)
	Region (II): = 239.64 mg/g = 0.1326 L/mg = 0.03

q_e: adsorbed amount at equilibrium; q_m: maximum adsorbed amount; C_e and C₀: equilibrium and initial concentrations, respectively; K_L: Langmuir rate constant; R_l: dimensionless constant . K_F: Freundlich rate constant; n: exponent of nonlinearity; R and T: ideal gas constant and temperature in Kelvin, respectively. b_T: Temkin isotherm constant; A_T: Temkin isotherm equilibrium binding constant; ε: Polanyi potential; ; E: adsorption energy ; k_ad: sorption energy constant.