Dissolution behaviour of iron silicate glass

A relationship between the water purifying effect and structure of 0.5xNa2O.0.5xCaO.5Fe2O3.(95-x)SiO2 glass (Na2O/CaO = 1; NCFS glass) with 'x' of 20 and 50 were investigated by means of 57Fe-Moessbauer spectroscopy, X-ray diffraction (XRD), induced coupled plasma optical emission spectroscopy (ICP-OES), as well as absorption spectroscopy, pH and oxidation-reduction potential (ORP) measurements. In the case NCFS glass with 'x' of 20, dissolved amounts of total Fe, Na+, and Ca2+ were respectively estimated to be 13.6, 39.1 and 36.7 mg/l, after 10 day-leaching test. On the other hand, the dissolved amounts of total Fe, Na+ and Ca2+ were determined to be 34.3, 647.6 and 667.6 mg/l, respectively when 'x' was 50. The original pH value of 6.0 was increased to 10.0 and 11.6 after leaching test of NCFS glasses with 'x' of 20 and 50, respectively. At the same time, the ORP value was decreased from 30.0 to -195.8 and -284.7 mV in the glasses with 'x' of 20 and 50, respectively.