Ethylenediaminetetraacetic acid (EDTA), a reagent with high carboxyl group content and strong coordination ability, can act as a modification chemical and impart the adsorbent materials with favorable metal chelating and ion-exchange
properties [21].
Some researchers [22,23] adopted the EDTA anhydride to modify the chitosan and baker’s yeast biomass. Their
results showed that the metal adsorption capacity of the modified biomass can be significantly enhanced. However, in their modification process, the two estolide groups of EDTA anhydride have the same reaction activity and both of them may react with the functional groups (hydroxyl or amino groups) of the biomass, and thus decrease the amount of carboxyl groups available for metal adsorption.
On the other hand, the interaction between the modified
biomass and metals is complicated. Few interaction mechanisms
involving both the ion-exchange and complexation for EDTA modified
biomass have been reported in the literature