Abstract
In order to obtain the tendency towards the formation of cadmium alginates, six kinds of sodium alginates were prepared and the values of metal/uronic acid residue ratio were investigated by precipitation and dialysis experiments. The guluronic acid residue alginate (G) and the mannuronic acid residue alginate (M) had the values about twice those of the insoluble fragment by partial acid hydrolysis (insoluble), the insoluble fragment at pH 2.85 (pH 2.85), the insoluble fragment at pH 1.5 (pH 1.5) and the commercial sample (CM). The correlation between the number average degree of polymerization (DP) and the affinity for divalent metals was not found. The affinity for heavy metals of sodium alginates increased markedly in both dialysis and two ions mixed experiments, and the maximum value of metal/uronic acid residue ratio came to about 2. On the other hand, the ratio for single ion by precipitation experiments was about 0.5.
