Adsorção de íons fosfato em óxido de nióbio hidratado

Abstract

The adsorption kinetics of phosphate on Nb2O5.nH 2O was investigated at initial phosphate concentrations 0.25, 0.50 and 1.00 mg.L-1. The kinetic process was described by a pseudo-secondorder rate model very well. The adsorption thermodynamics was carried out at 298, 308, 318, 328 and 338 K. The positive values of both ΔH and ΔS suggest an endothermic reaction and increase in randomness at the solid-liquid interface during the adsorption. ΔG values obtained were negative indicating a spontaneous adsorption process. The Langmuir model described the data better than the Freundlich isotherm model. The effective desorption could be achieved using water at pH 12.