EFFECT OF PHENOLS ON THE POLAROGRAPHIC AND SPECTRAL BEHAVIOR OF HEXAVALENT MOLYBDENUM IN SULFURIC-ACID-SOLUTIONS

The polarographic and spectral behaviour of hexavalent molybdenum in sulphuric acid solutions have been studied in the absence and presence of phenols. The processes of reduction pass ultimately to trivalent molybdenum via two to four reduction waves depending on the acid and the phenol concentrations. The presence of resorcinol or pyrogallol causes the reduction waves to split or intermingle due to the surface activity of the phenols. In the presence of high concentrations of pyrogallol, the sulphate complexes transform into the pyrogallol complex. Also, these phenols cause the polymerization of the monomer molybdenum species. The nature and the kinetic parameters of the waves in different media have been investigated.