Thermochimica Acta, Vol.589, 107-113, 2014
Thermodynamics of the nickel, cobalt and zinc removal from ethanolic solution by p-aminobenzoic acid intercalated on layered calcium phosphate
Crystalline lamellar calcium phosphate retained p-aminobenzoic acid inside its cavity without leaching. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 6.44, 3.34 and 1.62 mmol g(-1) for nickel, cobalt and zinc, respectively. The energetic effects caused by metallic cation interactions were determined through calorimetric titration at the solid/liquid interface and gave a net thermal effect that enabled enthalpy and equilibrium constant calculations. Complete thermodynamic data composed of exothermic enthalpy, negative free Gibbs energy and positive entropy conformed to a set of favorable cation/basic center interactions, to indicate that these materials could be useful tools to eliminate undesirable cations from ethanolic systems. (C) 2014 Elsevier B.V. All rights reserved.