Tentacle Ion Exchange Separation of Pb−NOM in Aquatic Systems

Abstract

The utilization of a new tentacle Fractogel dimethylaminoethyl (DMAE) anionic exchanger for the separation of metal−organic species in natural freshwaters is investigated using synthetic solutions and natural waters. Lead and alginate were used as model compounds in these experiments. The acid−base and metal complexation properties of the ligand were characterized by proton and metal titrations, respectively. The chemical speciation of Pb in the presence of alginate was calculated from the parameters derived from the titrations and compared to the anionic exchanger separations. The good correlation between the predicted and measured speciation showed that the tentacle ion-exchange resin retained the total Pb−alginate fraction. Therefore, this separation method was used to determine the fraction of Pb complexed to dissolved organic matter in the water column of a small lake which contained low (max. 2 nM) total dissolved Pb concentrations. The resin did not alter the speciation during separation and did not contaminate the samples.