Electrochemical study on the redox behavior of selenium-containing soda-lime-silica melts

Abstract

Decolorization of white container glasses nowadays is usually achieved by the addition of selenium compounds to the batch. Most of the quantity added, however, is evaporated during melting which is strongly influenced by the redox state of the melt. Therefore, the redox behavior in selenium-doped soda-lime-silica melts was studied by square-wave-voltammetry. The current-potential curves recorded showed two peaks, attributed to the reduction of SeO3 to SeO2 and SeO2 to Se^0. Under reducing conditions, selenium predominantly occurs as Se^0, which gives rise to the pink color. When melted under oxidizing conditions or, however, when the melt is kept at high temperature in air, the cooled glasses are nearly colorless due to the re-oxidation of Se^0 to SeO2. Keeping the melt at high temperatures for up to 50 h did not result in a notable evaporation of selenium compounds. Highest selenium contents were achieved by adding ZnSe to the batch.