Water Content on Metal Oxides. I. Water Content on Silica Gel, Magnesium Oxide, Zinc Oxide, and Titanium Dioxide

Abstract

The surface water content has been determined on silica gel, magnesium oxide, zinc oxide, and titanium dioxide by means of active hydrogen analysis and by the successive-ignition-loss method. Except for magnesium oxide pretreated at 100 °C, it has been found that the water contents obtained from the two methods on every oxide tested are in good agreement with each other. The successive-ignition-loss method gives an extraordinarily high value of water content on magnesium oxide pretreated at 100 °C, probably because of the retention of inner hydroxyl groups. The present results indicate that the two methods are equally reliable for the quantitative determination of the water content on metal oxides. Moreover, the simultaneous application of both methods make it possible to estimate each amount of surface hydroxyl groups and physisorbed water molecules.