Estimation of boron in sodium borosilicate glass frit by fusion at lower temperature

In India High level radioactive liquid waste is immobilized in sodium borosilicate glass matrix. Chemical characterisation of the glass frit is essential to decide the waste to glass frit ratio for vitrification operation. Dissolution of glass sample for its characterization is done by fusion with Sodium carbonate at high temperatures. The error in the estimation of Boron in this fused glass is high due to volatalisation of boron at high temperature. Present paper details the use of sodium hydroxide as flux for fusion of glass sample at lower temperature. The boron is estimated by alkalimetric titration in presence of glycols like glycerol. The effect of presence of other glass components was also studied. Estimation of only boric acid with out fusion has shown recovery of 99.0 %. The boron recovery after fusion with NaOH pellets was found to be 97 - 98 %. The recovery of boron in presence of glass components like Fe2O3, TiO2 and SiO2 together has indicated recovery of about 97-98 %. Further for the sodium borosilicate glass samples the recovery obtained is 92-94%. The lower value is due to the volatilization of boron during glass preparation. (author)