Abstract

SOARES, Marcio Roberto; ALLEONI, Luís Reynaldo Ferracciú  and  CASAGRANDE, José Carlos. Thermodynamic parameters for boron adsorption reaction on highly weathered tropical soils. Quím. Nova [online]. 2005, vol.28, n.6, pp. 1014-1022. ISSN 0100-4042.  http://dx.doi.org/10.1590/S0100-40422005000600016.

The driving force of boron adsorption on some tropical soils was evaluated by means of thermodynamic parameters. The batch method was employed, and the reaction was monitored at different pH values. The Langmuir equation successfully fitted the experimental results and provided reasonable isotherm parameters. Boron adsorption increased as a function of the pH of the soil solution and the concentration of added boron. The reaction was favorable and proceeded spontaneously, being strongly exoergic, as indicated by a negative free energy (DG) and a separation factor (K_R) < 1. The boron adsorption phenomenon and the soil-solution interface were thermodinamically described using a theoretical model.

Keywords : tropical soils; boron; adsorption.