Pyridineimdamide derivatives - Efficient zinc(II) extractants.

Novel extractants, hydrophobic N ′-alkyloxypyridine-2-, -3- and -4-carboximidamides, were proposed as the efficient zinc(II) extractants from acidic chloride solutions. In this study various factors affecting zinc(II) extraction, such as concentration of chloride ions, mineral acid and zinc in the aqueous feed solution, structure and concentration of the extractant and type of the organic diluent were studied. It was found that the extraction of Zn(II) was observed for the pyridine-3- and 4-carboximidamides with 2-ethylhexyl group and the extraction abilities increased with the increase of chloride ions concentration. N ′-(2-ethylhexyloxy)pyridine-4-carboximidamide appeared to be the most efficient extractant, as well as, it was the most suitable in terms of loading capacity. It was also found that 4-EH enabled a complete transfer of Zn(II) from the concentrated aqueous solution by using a two-stage counter-current extraction at an O/A ratio of 7.5 or at O/A = 8 by using a one-stage cross-flow extraction. [ABSTRACT FROM AUTHOR]