Behavior of ionic and colloid forms of microelements in colloidal chemical extraction from humic acid solutions

Speciation and extractability of humic acids (HAs) and humate complexes of microelements are studied using the colloidal chemical extraction method in combination with ICP MS with an example of natural mineral water with high HA concentration (800–1200 mg l^?1) collected from the Salekhard region. Joint extraction behavior of ionic and colloid forms of anionic and cationic species of a large number of microelements, including U(VI) and Th(IV), and HAs is examined at their natural abundance in mineral water, as influenced by pH and HA concentration. Humic acids proved to behave in natural water as a pool of ion-colloidal species, whose protonation results in precipitation at pH 2.0–3.5. In this case, some chemical elements are sorbed on the resulting solid and may be separated along with HAs by colloidal chemical extraction into isobutanol. In natural humate solutions, a considerable fraction (10–99 mol %) of chemical elements is associated with HAs in the form of colloid species extractable with isobutanol.