Synergistic Extraction of Cobalt(II) with Dithizone and 1, 10-Phenanthroline

Abstract

Synergistic effect of 1, 10-phenanthroline(phen) on the extraction of cobalt(II) with dithizone (H₂dz) was investigated and the extraction of cobalt(II) into chloroform was found to proceed according to the following equation:
Co²⁺ 2 H₂dzorg phenorg Co(Hdz)2(Phen)org + 2 H⁺
The resulting reddish adduct had an absorption maximum at around 521 nm, the molar absorptivity being 3.4 1O^2- dm3ol-1m^-1. The effect of 1, 10-phenanthroline on the above extraction was summarized as follows. ( 1 ) The extraction of cobalt (II) with dithizone was accelerated. ( 2 ) Stabilization of the oxidation state of cobalt( II ) in the dithizonato complex and the enhancement of the extractability of cobalt (II) caused by the formation of an adduct were observed. ( 3 ) Masking effect due to the formation of Co(phen)s in the aqueous phase was alSo found.