ACID-BASE PROPERTIES OF A RIVER SEDIMENT - APPLICABILITY OF POTENTIOMETRIC TITRATIONS

The application of potentiometric titrations to the study of the acid- base properties of a river sediment was investigated. A set of alkalim etric titrations were performed on suspensions containing different se diment-solution ratios and EMF measurements were elaborated by a suita ble computer program. After the optimisation of the titration procedur e, it was possible to refine conditional acid constants. For the consi dered sediment it was possible to calculate three protonation constant s. Comparing calculated pK(a) with those reported in literature for th e characterisation of humic and fulvic material of various origins and for inorganic hydrous oxides, it appears that calculated values are i n the range indicated for the assignment of the constants to organic a nd inorganic titratable groups that can be present on the surface of a natural sediment.