No abstract

The interactions of Zn(II) and Cu(II) with humic acids (HA) were characterized by potentiometric titration, IR and fluorescence spectroscopy. The equilibrium constants determined were Log([Zn(Cat)]/[Zn+2][Cat]) = 15.25, Log([Zn(Cat),]/[ZnCat][Cat]) = 9.80, Log([Zn(Cat)(Sal)]/[Zn(Cat)][Sal]) = 8.59, Log([Zn(Cat)(Pht)]/[Zn(Cat)][Pht]) = 3.71, Log([Zn(OH)(Cat)2][H+]/[Zn(Cat),]) = -8.91, for the Zn(II) system, and Log([Cu(Cat)]/[Cu][Cat]) = 18.45, Log([Cu(Cat)2]l[CuCat][Cat]) = 14.18, and Log([Cu(Cat)(Sal)]/[Cu(Cat)][Sal]) = 8.44 for the Cu(Il) system The amounts of each group detected by potentiometric titration were: phenol = 0.666, carboxylic = 1.042, catechol = 0.540, phtalic = 1.163, and Salicylic= 0.810 mrnoles per gram of HA, and the speciation curves were calculated.