Effects of pH, temperature, and organic and inorganic ions on the dissolution kinetics of humic acid particles

M. BRIGANTE; G. ZANINI; M. AVENA

Moscú-San Petersburgo

Congreso; 14th Meeting of the International Humic Substances Society; 2008

International Humic Substances Society (IHSS)

Humic acids (HA) are very active in binding ions, organic molecules and solid surfaces, and may influence markedly the transport of pollutants in natural waters. HA molecules are mainly transported by water in the environment and thus it is very important to understand how HA particles dissolve and at which rate they dissolve. This work presents experimental data on the dissolution kinetics of HA particles. All experiments were performed by UV-Vis spectrophotometry and the effects of pH, temperature and presence of divalent cations, carboxylic acids and herbicides are mainly analyzed. The results suggest that the cationic species, both organic and inorganic, cause a decrease in the dissolution rate of HA particles, whereas anionic species increase the dissolution rate. These effects on the dissolution rate depend on the type of interaction between HA molecules and the reactant species, including electrostatic, H-bonding, and hydrophobic interactions.