Comparison of techniques for the separation and pre-concentration of metal ions in aqueous solution

Abstract

A comparison is made between solvent extraction and column chelation procedures for the separation and pre-concentration of copper from natural waters. The solvent extraction system was ammonium tetramethylene dithiocarbamate (ammonium pyrolidine dithiocarbamate, APDC) as the complexing agent and isobutyl methyl ketone as the extracting solvent. The column material was immobilised 8-hydroxyquinoline on a controlled pore glass support. The final determination of the pre-concentrated element was accomplished by atomic-absorption spectrophotometry using a flame source.

Results at the p.p.b. level for standard solutions of copper gave recoveries of better than 98% from both procedures. The determination of copper in natural waters showed higher results by the column procedure, suggesting that column extraction was more efficient than solvent extraction. The column procedure was less time consuming and less costly than solvent extraction.

The determination of lead at the p.p.m. level and with copper present gave a recovery of better than 99% when employing 8-hydroxyquinoline column separation. Copper, however, was only separated to the extent of 70% from the same solution of mixed elements.