Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue.
A simple method is described for the separation of molybdenum from titanium, zirconium, chromium, manganese, iron, cobalt, nickel, uranium and aluminium in a wide variety of samples in <30 min. Phosphomolybdenum blue is produced by boiling for 2 min a molybdate solution containing phosphate to give Mo/P = 20-37 (w/w) with hydrazine sulphate in 0.1N sulphuric acid. The volume and acidity are adjusted to give a molybdenum concentration of 0.6-5 my/ml in 0.4-0.5N sulphuric acid. The phosphomolybdenum blue is 99.5% extracted with methyl isobutyl ketone in a single extraction. The residual molybdenum and hydrazine in the aqueous phase are oxidized with a few drops of liquid bromine and the molybdenum is quantitatively extracted with the same solvent from 1N sulphuric acid as its reddish brown thiosulphato complex. The molybdenum is stripped by ammonia-hydrogen peroxide solution. The back-extract is heated to boiling and filtered to remove the insoluble hydroxides of traces of accompanying elements. The thiosulphate in the filtrate is destroyed by boiling for 4-5 min with excess of hydrogen peroxide in slightly ammoniacal medium. The molybdenum is determined finally by cerimetry or other standard methods.
Yatirajam
V
V
Chemistry Department, University of Kurukshetra, Kurukshetra, India.
Ram
J
J