Regeneration of bonding agents loaded with heavy metals by electrodialysis with bipolar membranes

A new process for the desorption and separation of heavy metal cations from different polymeric bonding agents using electrodialysis with bipolar membranes was studied. To this end a membrane stack for the electrodialysis process, consisting of bipolar and cation exchanger membranes arranged in alternating order, was set up. In this study, four water-soluble bonding agents, carboxymethyl cellulose (CMC), pectine (PEC), polyethylenimine (PEI) and a newly developed dendritic benzoylthiourea-functionalised polyamidoamine derivate (DENBT) as well as a powdered cation exchanger (CEX) were used as polymeric bonding agents. The main focus centres on tests to determine the regeneration properties of these polymeric bonding agents. The regeneration rates as well as the electric resistance values of the membrane stack were determined for every bonding agent loaded with copper cations. Furthermore, the regeneration rates for CMC loaded with the different metal cations Cu2+, Ni2+, Co2+ and Pb2+ were determined.