Development of a copper selective silica-polyamine composite

Silica-polyamine composite materials have been developed that have the ability to extract metal ions from aqueous solutions. These materials are synthesized through a unique route that renders them chemically robust enough to withstand the rigors of extreme pH environments encountered in industrial processes. They also extract metal ions to a lower final concentration and at faster flow rates than the current standard polystyrene resin bead materials. Modifications of these materials can be made, usually through straightforward chemical reactions, to tune their selectivity, to enhance the extraction of a particular class of metal ions. Early modifications of the silica-polyamine materials were successful in increasing the affinity and adsorptive capacity for the soft metals, for instance. But the new materials were not exclusively selective for that target class. The focus of the work presented here is development of a material selective for copper(II) extraction, even in the presence of large concentrations of iron(III).; The important features of the parent silica-polyamine materials such as the chemical and physical integrity of the material, and the ability to extract metal ions efficiently from low concentration solutions at fast flow rates, are explored in some detail. The critical synthetic steps are also thoroughly investigated.; Finally the synthesis and performance characteristics of a new copper selective silica-polyamine composite material—CuWRAM—are presented. CuWRAM was tested under batch and flow conditions using synthetic and real world challenge solutions. Many of these tests were carried out using CuWRAM and the industry standard Dowex XFS 45084 for a direct comparison. It has been demonstrated that CuWRAM is more effective than the Dowex resin under flow conditions, low pH, and under conditions of low metal ion concentration.