Hydrotalcite Formed by Alteration of R7T7 Nuclear Waste Glass and Basaltic Glass in Salt Brine at 190°C

Abstract

ABSTRACTThe R7T7 and synthetic basaltic glasses were submitted to corrosion in a saline MgCl2dominated solution at 190°C. For both glasses, the early alteration product is a hydrotalcite-like compound in which HPO42-, SO4-2and Cl-substitutes to CO32. The measured d003spacing is 7.68 Å for the hydrotalcite formed from R7T7 glass and 7.62 Å for the hydrotalcite formed from basaltic glass which reflect the high aluminium content. Chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after few months.