Complexes of humic acids and fulvic acids with heavy metals
1998
Tobiasova, E. | Zaujec, A. (Slovenska Polnohospodarska Univ., Nitra (Slovak Republic))
This paper presents results from a series of potentiometric titrations aimed at characterization of acidic functional groups of a humic acid (HA) and a fulvic acid (FA) and formation of complexes (Cd, Cu, Ni, Pb, Zn) with these acids. The preparations tested of HA and FA were obtained from oxihumolits, and their characteristics are not therefore entirely identical to those of the soil HA and FA. The technology itself of their gaining affected the sorption capacity and the buffer ability of different preparations. The said values decreased with an increase in the technology agressivity. The ionization itself of acidic functional groups was also affected by ash content. The inflex points corresponding to the dissociation of weak and very weak functional groups were more expressive at a higher content of ash. The order of heavy metals by stability of their complexes was as follows: Cd2+ Zn2+ Ni2+ Cu2+ Pb2+. The preparations examined had different chemical properties. Therefore, their efficiency will be different if they are used as sorbents of heavy metals in soil
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