Activated carbon obtained by pyrolysis of potato peel for the removal of heavy metal copper (II) from aqueous solutions

Activated carbons (ACs) were prepared by pyrolysis of potato peel in presence of zinc chloride (chemical activities). Potato peel from Colombian cultives were impregnated with aqueous solutions of ZnCl2 following a variant of the incipient wetness method. Different concentrations were used to produce impregnation ratios of 40, 70, 110 and 160 wt.%. Activation was carried out under argon flow by heating to 823 K with 4 h soaking time. The porous texture of the obtained ACs was characterized by physical adsorptions of N2 at 77 K and CO2 at 273 K. The impregnation ratio had a strong influence on the pore structure of these ACs, which could be easily controlled by simply varying the proportion of ZnCl2 used in the activation. Thus, low impregnation ratio led to essentially microporous ACs. At intermediate impregnation ratios, ACs with wider pore size distribution (from micropores to mesopores) were obtained. Finally, high impregnation ratios yielded essentially mesoporous carbons with high surface area and pore volume. The four best-fit three-parameter isotherms Sips, Toth, Radke–Prausnitz and Vieth–Sladek suggest that the sorption capacity of activated carbon of potato peel to uptake copper ions to be 74 mg/g.