Cadmium complexation by soil fulvic acid

Abstract

A soil fulvic acid bas been characterized and the complexation stability constants with cadmium have been evaluated. The average gram formula weight of the fulvic acid is 2775. Three complexes of stoichiometry CdFA, Cd 2 FA, and Cd 3 FA have been observed. The respective conditional stability constants at pH 5.7 are 10 5.3 , 10 9.8 , and 10 14.0 ; at pH 6.7 they are 10 5.6 , 10 10.6 , and 10 15.5 ; and at pH 7.7 they are 10 6.0 , 10 10.7 , and 10 15.4 .