The retention of metal species by different solid sorbents - Mechanisms for heavy metal speciation by sequential three column uptake

An apparatus consisting of three columns packed with different substrates, namely an anion exchange resin, a reversed phase sorbent and a chelating io n exchange resin, was developed. The retention of cadmium, copper and lead onto the substrates at different pH conditions was investigated, first by c onsidering each column separately, then by connecting them in series. The a im of the study is to distinguish among species with different charge or ch emical behaviour. Experiments were performed with the free metal ions, thei r anionic complexes with EDTA and 8-hydroxyquinoline-5-sulphonic acid, and their neutral complexes with 8-hydroxyquinoline. The results obtained were compared with those computed according to the theoretical species distribut ion of all species as a function of pH. The applicability of the technique to seawater was demonstrated. (C) 2000 Elsevier Science B.V. All rights res erved.