Removal of Ions from the Solution by Surface Active Glasses

초록

Most of commercial glasses are chemically inert. Some glasses with special composition, however, show poor chemical durability , and sometimes crystals can be precipitated on the surface of those kinds of glass. Leaching of various alkali and alkaline earth ions from the glass surface in an aqueous solution produces silica rich layer on the glass surface. The ions present in an aqueous solution can be precipitated on the silica gel layer to form crystals. The crystalline phase strongly depends on the glass composition, pH of the solution and the ions in the solution. When a surface active glass is reacted in a simulated body solution, Ca2+ and P5+ ions, which are leached out of the glass, precipitate on the surface of the glass and crystallize into hydroxyapatite. In this way, Ca2+ and P5+ ions can be removed from the solution. If the solution contains some other ions, such as Pb2+, CO32- and SO42-, crystals, such as pyromorphite [Pb5(PO4)Cl2], carbonate and sulfate,respectively, which contains above mentioned ions can be precipitated on the glass surface. The influence of pH and temperature on the formation of those crystals was significant.