Solvent Extractioh and Spectrophotometric Determination of Cobalt( III) and Iron( III) with N-Hydroxy-N ,N '-Diphenylbenzaihdine in Presence of Azide.
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Date
1982-06
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Addis Ababa Universty
Abstract
N-'Hydroxy-N ,N' -diphenylbenzamidine (HDPBA)" a
bidentate chelating agent, reacts with cobalt(III) and
ironeIII) in the p,resence of azide to give a pinkish
red and red-violet coloured mixed ligand complexes,
which are quantitatively extractable into chloroform
from the aqueous phase at pH 7.4-7.8 and 2-5 respectively,.
allowing spectropJiotometric determinations of the metal
ions. The cobalt(III) and iron(III) mixed ligand
complexes have wavelengths of maximum absorption at
520 and 520-540 run with their respective molar absorptivities
of 1980 lit. mole-l cm-l and 4895 lit. mole-I
cm-l • Beer's Law obeys from 3.6 to 24 ppm for cobalt(III)
and from 1.6 to 11.2 ppm for iron(III). The effect of
foreign ions and several other experimental variables
have been studied., The composition of the cobalt(III)
and iron(rII) mixed ligand complexes have been determined
by spectrophotometric methods- and ilre found to be 1:1:2
(Co: HDPBA:N:3) and 1:2:2 (Fe:HDPBA:l{'3) respectively.
On the basis of the differences in the pH of the
react'ion media for irone III) and cobal t( III), a separation
procedure for the two metals in a solution has been
established folloHed by spectrophotometric determinations.
The method has allowed the separntion and determination
of varied proportions of ironeIII) and cobalt(III) in a solution of the two metal ions. ,Moreover, the methods have been applied successfully for the separation and
determination of cobalt and iron in synthetic samples.a solution of the two metal ions. Moreover, the methods have been apr;lied successfully for the separation and
determination of cobalt and iron in synthetic samples