Differential scanning potentiometry: surface charge development and apparent dissociation constants of natural humic acids

Humic acids (HA) are the main components of soil organic matter which can form complexes with metal ions and other soil and/or water contaminants. Here, we focus on their acid–base properties. HA were extracted from two different soils (Tipic Ustifluvent and Entic Haplustoll) with different vegetation. In this study we use a simple method, differential scanning potentiometry (DSP), to determine HA buffer capacity distribution, apparent dissociation constant values and surface charge development.