Influence of Temperature and Water Vapour Pressure on Drying Kinetics and Colloidal Microstructure of Dried Sodium Water Glass
Read full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=53263#.VLiDr8nQrzE Author(s) Hans Roggendorf * , Matthias Fischer , Robert Roth , Reinhold Godehardt Affiliation(s) Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany . ABSTRACT Industrially produced sodium water glasses were dried in climates with controlled temperature and humidity to transparent amorphous water containing sodium silicate materials. The water glasses had molar SiO 2 :Na 2 O ratios of 2.2, 3.3 and 3.9 and were dried up to 84 days at temperatures between 40°C and 95°C and water vapour pressures between 5 and 40 kPa. The materials approached final water concentrations which are equilibrium values and are controlled by the water vapour pressure of the atmosphere and the microstructure of the solids. The microstructure of the dried water glasses was characterized by atomic force microscopy. It has a nano...