METHOD FOR ON-SITE DETERMINATION OF RESIDUAL ADSORPTIVE CAPACITY OF CHARCOALS USED IN CLOSED ENVIRONMENTAL SYSTEMS. PART II. TEMPERATURE CHANGES DURING DESORPTION OF MOISTURE FROM CHARCOALS

The relationship between the temperature decrease accompanying the desorption of water from adsorbent-type charcoals and their residual adsorptive capacity for organic compounds was studied. Investigation of fourteen charcoal samples from submarine main-carbon filters has shown that the time at which the minimum temperature of a charcoal sample undergoing water desorption is reached is proportional to its moisture content and correlates with the organic loading determined by steam desorption. The simple apparatus previously devised for determining the moisture content of a charcoal sample (NRL Memorandum Report 1710, August 31, 1966) was used to recirculate air in a closed-loop system, and transfer water from a charcoal sample to a desiccant. Temperature changes during the desorption process were conveniently displayed on a chart recorder which monitored a thermocouple located in a charcoal sample. Under conditions where the previously reported weight change procedure is not practical, the temperature change method is an alternative means for determining the residual adsorptive capacity of a charcoal. (Author)