CHARACTERIZING A NEW CLASS OF SORPTIVE DESORPTIVE ION-EXCHANGE MEMBRANES FOR DECONTAMINATION OF HEAVY-METAL-LADEN SLUDGES

Selective removal of small amounts (<5%) of heavy metal precipitates from the background of innocuous solids in a sludge or slurry system is a challenging separation problem. Conventional fixed-bed sorption processes and membrane separation processes are unable to handle sludges/slurries with high suspended solids (1-10%) contents. This study identifies and investigates a new type of composite sorptive/desorptive membrane made of fine particles of chelating polymers entrapped in thin sheets of porous poly(tetrafluoroethylene) (PTFE). These membranes are not fouled by high concentrations of suspended solids but retain the original properties of the chelating exchangers. Various physicochemical properties of the sorptive/desorptive membranes are discussed at length in the context of decontamination of heavy-metal-laden sludges.