To remove maximum amount of acid and iron from theWSA and
the DASE, the aqueous feed was contacted with the organic phase
for different times. The phase ratio (O/A) was 6:1, and the stage
of the counter current is two. The experiments were performed at
temperature of 25 ◦C with feed of 0.56 mol/L Fe(II) and 3.1 mol/L
sulfuric acid. The results are presented in Fig. 12. It indicates that
the stripping yield of Fe(III) increases steadily from 91.1% to 99.5%
with the increase of reaction time from 2 to 8 min, and it increases
slightly from 99.5% to 99.8% with the increase of agitating time from
8 to 12 min