The dissolution kinetics of humic acid particles

M. BRIGANTE; G. ZANINI; M. AVENA

Kyoto, Japan

Congreso; 5th International Conference Interfaces Against Pollution 2008; 2008

Japan Society for the Promotion of Science (JSPS)

A study of the dissolution kinetics of solid HA particles is presented here, and the ability of HA to become solubilized in aqueous media by different substances and conditions is evaluated. Thus, the effects on the dissolution rate of pH, temperature, concentration of inorganic and organic cations, organic acids and pesticides are investigated. The results show that the dissolution rate is strongly dependent on the pH of the aqueous solution; there is a 400-fold increase in the dissolution rate by increasing the pH from 4 to 11. Cations, either organic or inorganic, usually decrease the dissolution rate whereas organic acids and anionic pesticides increase that rate at constant pH. Dissolution appears to be controlled by sorption-desorption processes at the solid HA-water interface. These sorption-desorption processes are believed to modify the attractive forces that hold HA molecules together in the solid, modifying their rate of detachment from the surface.