Electrochemical Reduction Behavior of Borosilicate Glass in Molten CaCl2

The electrochemical reduction behavior of borosilicate glass, which is the main component of vitrified radioactive waste, was investigated in molten CaCl2 at 1123 K to establish a new nuclear waste disposal procedure. Cyclic voltammetry of borosilicate and silica glasses suggested that the reduction of B2O3 in borosilicate glass occurred at a more positive potential than that of SiO2. X-ray photoelectron spectroscopy confirmed that the B2O3 component was reduced to B or a B-Si compound at 0.9 V vs. Ca2+/Ca. The reduction products prepared by the potentiostatic electrolysis of borosilicate glass at 0.9 V had granular morphology and consisted of crystalline Si. The Al2O3 component was not reduced at 0.9 V and the Na2O component was suggested to be dissolved in molten CaCl2 during electrolysis. (C) 2016 The Electrochemical Society. All rights reserved.