Conductimetric analysis of the ion binding properties of three leaf extracts of chestnut (Castanea sativa), Eucalyptus (Eucalyptus globulus) and oak (Quercus robur).

Humic materials extracted from tree leaves of chestnut (Castanea sativa), eucalyptus (Eucalyptus globulus) and oak (Quercus robur) were analyzed by performing conductimetric titrations. Values between about 84 and 236 muS cm(-1) for the molar conductivity and between 0.42 and 0.74 for the charge distribution parameter were obtained when the concentrations of the extract are increased from 40 to 100 mg 1(-1). These variations were explained by using the counterion condensation theory, and the distance between the charged groups of the polyions, the volume of the counterion condensation and the Debye-Hückel potential were also calculated.