Abstract
The dissolution kinetics of solid humic acid (HA) particles under different conditions is reported and analyzed. The dissolution rate at pH 4 and 5 is very slow and several years may take to achieve equilibration. The rate is strongly increased by increasing pH, and at pH 11 complete dissolution is achieved in 30 min. The dissolution rate is also markedly increased by the presence of monocarboxylic acids and anionic herbicides such as glyphosate and 2,4-D. On the contrary, the rate is decreased by inorganic divalent cations (Mg 2+, Ca 2+, Sr 2+, Ba 2+). The divalent cation paraquat has a dual behavior, decreasing the dissolution rate at pH >7 but increasing it at pH <7. Simple modeling assuming a surface-controlled dissolution kinetics can reproduce reasonably well the effects of anions and cations. The different ions seem to affect the dissolution rate by modifying intermolecular forces between HA molecules located at the surface of the particles.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Colloids and Surfaces A: Physicochemical and Engineering Aspects
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
