UV characterization of sulphide-polysulphide solutions and its application for process monitoring in the electrochemical production of polysulphides

The UV spectral characteristics of some sulphur species of relevance for the electrochemical production of polysulphides have been studies. It was found that an isosbestic point exists in the hydrogen sulphide ion-polysulphide solution. The absorption at this point (249 nm) is proportional to the total sulphur concentration in the solution. The investigation also shows that the spectrum of a polysulphide solution can be regarded simply as the sum of contributions from charges hydrogen sulphide ion and zero-valent sulphur in polysulphides although a complicated equilibrium distribution of different species exists in the polysulphide solution. The spectrum provides enough information for the measurement of these forms of sulphur. Based on spectrophotometric measurements, a simple monitoring for changed hydrogen sulphide ion and polysulphide excess sulphur in the process liquor can be realized.
QC 20100518