粘土中の吸着水の研究(第1報) ―差動熱量天秤による吸着水のエントロピーの測定―

Abstract

This paper described the results of experiment carried out by TG-DSC apparatus in order tomeasure the heat of evaporation of water adsorbed on clays. A small quantity of sample powder, 18.0 mg for Osaka Nanko Clay or 12.2 mg for Osaka Umeda Clay, was put in a Al-pan in thesize of 5 mm diameter and of 3 mm depth and was set on sample holder of the apparatus alongsideof Al-pan in the same size which contained the a-Al2O3 powder as reference materials. About10 mg of distiled water was poured into clay sample and was evaporated at room temperature.After the cease of spontaneous evaporation, both pans were heated at the rate 1.25℃/min up to a des-ignated temperature and were held at that temperature until the decrease of weight was not reco-gnized on TG record. They were heated again to the next designated temperature at the same rateand, also were held at that constant temperature until the stop of weight loss. Such procedures ofheating were continued up to about 150℃. Corresponding to each rising stage of temperature, DSC record showed the endothermic peak curve. Since the peak area was accepted to the amountof heat required to the evaporation of water mass indicated by respective weight loss on TG-record, evaporation heat of adsorbed water was determined at each stage of temperature and then, the inceaseof entropy due to the evaporation could be estimated from this evaporation heat divided by meanvalue of constant temperatures before and after heating. In comparison with the entropy of normalwater at 1 atm pressure, refered to the ice at 0°K, the result was that adsorbed water on sampleclays had negative values of entropy at all mean temperatures.