Chelating extraction of vanadium(V) from low pH sulfuric acid solution by Mextral 973H

In the current study, a novel chelating extractant Mextral 973H was employed to selectively extract V(V) from a low pH sulfuric acid solution containing high concentration of Fe (Ш). The extraction of V(V) is strongly dependent on solution pH, and the separation coefficient (β(V/Fe)) between V(V) and Fe(Ш) can be greater than 720 when the solution pH < 0.5. A cation exchange between H and VO2+ was proposed as the main extraction mechanism at pH < 1.5, while at pH > 1.5, a solvating reaction between the extractant and metal-oxo cluster anions took place. The effects of solution pH, acid medium types, contacting time and temperatures on the extraction and separation of V have been discussed. FT-IR and 1HNMR were applied to confirm the extraction mechanism and also the degradation behavior of Mextral 973H in some extreme conditions. The loaded vanadium was effectively stripped using a diluted 0.2 M Na2CO3 solution and a total stripping extent of 97% was achieved. The extraction process by Mextral 973H was finally simulated using Aspen Plus simulator comparing to traditional process, the results obtained were in good recovery efficiency and with the advantage of acid and alkali saving.