Isolation and Concentration of Traces of Lead with Strontium Sulfate
Abstract Lead in trace quantities is co-precipitated as the sulfate with milligram quantities of strontium carrier, using dilute sulfuric acid. The precipitate is separated from the excess sulfate by centrifuging and is then converted to the carbonate by agitation with ammonium carbonate solution. The carbonate precipitate is separated, dissolved in a slight excess of hydrochloric acid, and then freed of carbon dioxide. The solution, buffered to a pH of 8.8, is immediately extracted with a solution of dithizone in chloroform, and the lead is determined spectrophotometrically. Recoveries are approximately 100% and moderate quantities of the following ions do not interfere: Cd; Co (II) ; Cu (II) ; Fe (II); Fe (II); Mn (II); Hg (II) ; Ni (II) ; Ag (I) ; and Zn. Cyanide buffer is not required, all the chemistry is done in the same centrifuge tube, and many samples can be analyzed simultaneously, using readily available equipment
Sustainable and efficient leaching of tungsten in ammoniacal ammonium carbonate solution from the sulfuric acid converted product of scheelite
