Study of the acid–base properties of three fulvic acids extracted from different horizons of a soil

摘要: Abstract Potentiometric titrations of three fulvic acids (FA) extracted from samples located at different horizons a soil were carried out various FA concentrations (40, 80 and 120 mg l −1 ) ionic strengths (0.01, 0.1 1.0 M KNO 3 ). Experimental data have been analysed by means the master curve approach which includes an electrostatic double layer model. Spherical cylindrical models fitted equally well. Heterogeneity analysis curves showed in all cases that affinity distribution had two peaks centred log K int H ∼4 ∼8–9 , respectively. A Langmuir–Freundlich isotherm was used for fitting data. The number weak acid sites derived equivalence point experimental titration matched maximum charge corresponding to more acidic carboxylic L–F quite Even though decrease observed with increasing concentration, we can conclude exhibit almost identical behaviour.