Comparison of Tests for Activated Carbons

Abstract

The task of preparing specifications for activated carbon suitable for the removal of tastes and odors from water is a formidable one, because it is a material with properties entirely different from those of other treatment chemicals with which the water-works industryis familiar. To prepare such specifications in a manner satisfactory to both the user and the manufacturer, has required an enormous amount of careful work by the Sub-Committee on Activated Carbons. Of the two methods which are now available for measuring the primary property of activated carbons, viz., their capacity for removing tastes and odors from water, one, the phenol test, is an indirect method, and the other, the threshold odor test, is a direct one. Extensive work has been done on the phenol test, to ascertain and correct sources of error, and to establish the magnitude of reasonable experimental error, now accepted as ±10 per cent. Work on the threshold odor test has now reached a point at which similar reliance is possible on that procedure as a method of evaluating adsorptive capacities of carbons. Demonstration of this reliability is based upon demonstration that in adsorbing odors from water, carbons follow the fundamental adsorption equation of Freundlich,