Sorption of Cu2+ and Co2+ from aqueous solutions onto sepiolite: An equilibrium, kinetic and thermodynamic study

Abstract

The efficiency of natural sepiolite for the removal of Cu2+ and Co2+ from aqueous solution was determined using the batch method. The sorption experiments were performed as a function of the initial metal concentration, the equilibration time and temperature. Thermodynamic parameters, such as enthalpy, free energy and entropy, were calculated from the temperature dependent sorption isotherms and these values showed that the sorption of the investigated metals onto sepiolite was endothermic. The pseudo-second order kinetic model provides the best correlation of the experimental kinetic data.

U radu je ispitana efikasnost uklanjanja jona bakra i kobalta iz vodenih rastvora na prirodnom sepiolitu primenom metode uravnotežavanja posebnih proba. Ispitan je uticaj početnih koncentracija Cu2+ i Co2+, kao i vremena uravnotežavanja i temperature na proces sorpcije. Vrednosti termodinamičkih parametara sorpcije (promene entalpije, promene entropije, promene slobodne energije sorpcije), određene na osnovu zavisnosti sorpcionog kapaciteta od temperature, ukazuju na to da je proces sorpcije Cu2+ i Co2+ na sepiolitu endoterman. Poređenjem eksperimentalih rezultata sa kinetičkim modelima utvrđeno je da se kinetika sorpcije Cu2+ i Co2+ na sepiolitu može opisati kinetičkim modelom pseudo-drugog reda.