Methodological Approach to the Study of the Formation and Physicochemical Properties of Phosphate−Metal−Humic Complexes in Solution

The aim of this work is to study the suitability of the complementary use of ultrafiltration (UF) and the interaction with an anion-exchange resin (AR) to characterize of phosphate−metal−humic complexes in solution. The results indicate that a methodological approach consisting of the validation and calibration of the AR method by the UF method and the further use of the AR method is suitable for characterizing phosphate−metal complexes. Such an approach has proven to be useful for calculating the phosphate maximum binding capacity of iron−humic complexes and stability constants. It might also be used to obtain valuable purified phosphate−metal−humic complexes for further structural characterization. Keywords: Humic substances; metal−humic complexes; phosphorus; phosphate; phospho-humic complexes; phosphate−metal−humic complexes; ultrafiltration; anion-exchange resin