Effect And Measurement Of Residual Water In Lithium Oxide Intended For Use As Electrolyte In Molten Salt Electrochemical Processing

초록

Li2O has applications for electrochemical processing of nuclear materials. Thermal dehydration leads to formation of oxide ions, which are shown to react and cause precipitation of dissolved CeCl3 that was selected as a surrogate for actinide chlorides. Thus, measurement of residual water in Li2O is an essential capability. Thermogravimetric analysis (TGA) was shown to underestimate starting water concentration. Subsequent analysis of solid samples via acid?base titration and cyclic voltammetry (CV) of the molten salt yielded consistent values within 5% for residual water. Hydroxides were shown to be unstable, thus oxygen is retained as oxide ions. Thus, total water in a sample of Li2O can be quantified by combining TGA with with either CV of molten salt or titration of salt samples. The importance of quantifying residual water in the salt was demonstrated by showing that cerium chloride (surrogate for actinide chlorides) will react with oxide ions in Li2O to form insoluble oxides and oxychlorides.