Abstract
Ethylenediaminetetraacetic acid (EDTA) was treated with diamine (p-phenylenediamine) and two triamines [2, 4, 6-triaminopyrimidine (A) and 1, 2, 4-triaminobenzene (B)] to prepare the polyamides which had chelate-forming ligands and could selectively adsorb (or desorb) heavy metal ions. The A-resin obtained by the reaction of EDTA-diamine-triamine (A) (10 : 9 : 2/3 in molar ratio) was found to have the minimal bulk specific gravity (0.36) and the maximal water absorbing capacity (225%). The bulk specific gravity increased and the water absorbing capacity decreased with an increase in molar ratio of the triamine. The B-resins obtained by the reaction of EDTA-diamine-triamine (B) had larger bulk specific gravity (0.630.69) and smaller water absorbing capacity (82104%) than those of A-resins. By comparing IR spectra of the two types of both A and B-resins, one type adsorbed copper ion and the other type adsorbed sodium ion, the carboxylate ion of the former type resin was seen to coordinate to the copper ion. From the above discussion on IR spectra and from results of pH-titration of both A and B-resins on the aqueous suspension in the presence of copper ion, it was concluded that copper ion was adsorbed by way of chelate-bonding by the resins. The experiments of the adsorption of 8 metal ions on a B-resin revealed that adsorption capacity was greatly dependent both on the ion species and pH.
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