Extraction of ammonia by commercial copper chelating extractants

Abstract

The extraction of ammonia by commercially available hydroxyoxime, β-diketone and quinoline sulphonamide extractants in the absence and presence of copper and nickel has been studied as a function of pH, diluent type and metal loading. Ammonia appears to be extracted by hydroxyoximes directly as the species RH·NH 3 and the data suggest that only the monomeric oxime is involved. Nonylphenol, used in the synthesis of the hydroxyoximes, was found to extract ammonia quite strongly and variation in uptake by various hydroxyoximes may be due to a combination of different nonylphenol contents and degree of oxime dimerisation. Metal loading of the organic phases with copper or nickel reduces the ammonia content. While neither the β-diketone reagent LIX 54 nor the sulphonamide reagent LIX 34 extracted ammonia in appreciable quantities in the absence of copper and nickel, copper loading caused a small increase in ammonia content and nickel loading caused a considerable increase in ammonia content with nickel: ammonia ratios suggesting the extraction of a nickel ammine complex.