Ceramics-Silikáty 54, (2) 139 - 143 (2010)

Two types of alkali alkaline earth silicate melts (Flint and PDP) containing sodium sulfate or blast furnace slag were prepared and the sulfur redox equilibrium was studied by square wave voltammetry. Voltammograms at different frequencies in the temperature range from 1000°C to 1400°C were produced. The voltammograms of both melts showed two reduction peaks at high frequency but only one peak at low frequency. The peaks shown in the voltammogram of the melts prepared from the blast furnace slag were weak but their potentials were same as those of the melts from the sulfate. Based on the diffusion coefficients determined from the relation between peak current and pulse time, it was suggested that the first peak around -500 mV was due to the reduction of S⁴⁺ to S⁰ and the second peak around -300 mV was related to the reduction of S⁶⁺ to S⁴⁺.