抄録
It is well known that the presence of even a small amount of vanadium in the electrolysis of brine by mercury method causes a marked lowering of current efficiency. The authors have been investigated a rapid method of estimation of a trace of vanadium in brine and commercial salt. To a sample solution acidified with hydrochloric acid, ferric salt (about 50mg Fe), hydrogen peroxide water and aqueous ammonia are added to precipitate ferric hydroxide, to which all the vanadium is absorbed and the precipitate is filtered, taken up in 20ml sulfuric aid (1:3), treated with 20ml sulfuric acid (1:1), 15ml phosphoric acid, 1ml approximately 0.1N ferrous ammonium sulfate and 5ml 20% urea solution, the vanadium is oxidized by adding dropwise 3% potassium permanganate, the excess permangate is decomposed by adding dropwise 3% sodium nitrite solution, also, the excess of nitrous acid is decomposed with urea previously added, the solution., is treated with 5ml 0.01% sodium diphenylaminesulfonate, made up to 100ml with water, the red purple colored solution is taken up in a cell and the light absorbency is estimated, using 570mμ, filter. The cell is then treated with a drop of approximately 0.1N ferrous ammonium sulfate for decolorization of red purple color due to vanadium and the vanadium is estimated from the differences in absorbency in these two estimations. The error in this method was ±2?3γ vanadium and the time required for the estimation was about 40 minutes. The vanadium in brine electrolyte was about30γ/l and that in salt was 0.00001?0.00004%, also the vanadium content in sludge obtained from refining of brine was 0.00017%.