GB839769A - Improvements in glass articles - Google Patents

Abstract

A glassy article comprises a microscopically porous vitrified glassy structure at least 90 cationic mol. per cent. of which consists of a combination of inorganic constituents of the composition set forth in the following table, in which the amounts are specified as cationic molar percentages:- .TiO2.0-40 .ZrO2.0-35 .HfO2.0-35 .TiO2 + ZrO2 + HfO2.10-40 .SiO2.0-40 .AlO1,5.0-10 .BO1,5.0-25 .PO2,5.20-70 .PO2,5 + BO1,5.20-75 .Fluxes.0-15 .BO1,5 + Fluxes.0,25 the fluxes being selected from the alkali and alkaline earth oxides; the structure having a maximum ion exchange capacity, as determined by the test described herein, greater than 2 milliequivalents per gram. Such articles can function as ion exchangers under extremes of temperature, pH, and radiative conditions and are resistant to oxidative influences and to attack by strong acid solutions. Thus they may be used, in an ion exchange application, to decontaminate strongly-oxidising, chromium-plating-bath solutions. They are mechanically strong, crack-resistant, and are structurally stable under extremes of temperature up to approximately 400 DEG C. and down to liquid air temperatures. Ionizing radiation does not cause a drop in their ion exchange capacity nor a significant degradation of their structure. They may be used in the removal of radioactive ions such as caesium and strontium from solutions of low pH at high temperatures of say, 250 DEG C. and under several thousand pounds of pressure. In addition, however, they are useful in chemical processes generally, e.g. as adsorbents or catalysts. Catalytic agents may be attached by ion exchange or adsorption and the resulting adsorbed ions reduced, in situ, if desired.