“A DSC Study of the Heat Capacity of Vicinal Water in Porous Materials”

Abstract

Vicinal water is belived to possess structures which differ notably from the bulk structure. if this is indeed true, then measureable differnces must be expected in the thermodynamic properties. Ling and Drost-Hansen (6) attempted a DTA study of water. in porous glass, and thd data obtainted were suggestive of diffrences in the properties of bulk water and water in narrow pores (range 20 nm to 200 nm). We have continued the study of thormodynamic propoties employing a DSC metgod utlizing different types of porous materials. The result to data have not provided firm additional evidence for the occurrences of thermal anomalies. However, the data do suggest that the heat capacity of water in porous glass, activated charcoal, a zeolite, and diamond powder is significantly larger than the value obtained for bulk water (measurd by the same technique). Assuming all the water present process a modified structure, the apparent heat capacity is at least 20% larger than that for bulk water; and, to a first approximation, Independent of the specific chemical nature of the solid material. This observation rules out the possibility that the anomalous values obtained in porous glass are due to some type of silicic acid formation. fourthermore, the substrate-independence agress qualitatively with the “para-doxial effect” observed for the temperature of vicinal water transitions [Drost-hansen, 3).