Dissolution behavior of a polyphosphate glass into an aqueous solution under static leaching conditions

The dissolution behavior of a polyphosphate glass with a molar ratio [M2O + MO]/P2O5>1 in distilled water under static condition was studied. The leaching tests were performed with glass powder samples (0.1-0.65 mm) at T=15-50 degrees C for times up to 720 h. The mass loss of the samples, the changes of pH and the concentration of elements (P, K, Ca, Mg, Zn and Mn) in solution were determined. The effects of temperature, time and particle size were analyzed. The results of the tests showed a complex dissolution behavior of this glass. The selective dissolution of the glass components was determined. The mechanism of formation and the structure of dissolved glass layer were investigated. The effects of cations on the mechanisms and kinetics of dissolution of the polyphosphate glass are presented. The activation energy of dissolution, Ea, was determined to be 39 +/- 5 kJ/mol. (C) 2012 Elsevier B.V. All rights reserved.