SELECTIVITY OF ALGINATE GEL FOR CU VS CO

The selectivity of the kelp alginate gel for copper compared to cobalt was investigated. When copper and cobalt existed at relatively high concentrations (100 ppm each), Na-alginate solution was directly dispensed into the mixed solution circulating in a loop fluidized bed reactor to produce Cu/Co-alginate gels in situ. Two extended Langmuir models were derived and tested against experimental data in this work: Model 1 was a general Langmuir model for two absorbates competing for the same type of binding site. Model 2 was based on the ''egg-box'' model for gelation of sodium alginate in the presence of divalent metal ions with the assumption that each metal ion would bind two carboxyl groups on neighboring uronate residues that formed the ''site''. It was found that Model 1 data better and parameters obtained from Model 1 were used to predict the amount of Na-alginate needed to ''polish'' a cobalt solution containing a trace amount of copper.