| Abstract: | Stability constants of complexes of four divalent metal ions viz. Cu2+, Zn2+, Mn2+ and Ca2+ with humic (HA) and fulvic acids (FA) at pH values of 7 and 8 were determined. The log K (logarithm of the stability constant) ranged from 3.09 to 7.77 and from 2.22 to 5.98 for metal-humic and metal fulvic acid complexes, respectively. Sequentially, the order of stability constants were as follows: Cu> Ca> Mn> Zn and Cu> Ca> Zn> Mn for metal -HA and metal-FA complexes, respectively, indicating a higher degree of complexation with Cu metal ion. |
