Surface area measurement by the sorption of stearic acid-1-carbon-14

Abstract

A technique was developed for determining the surface area of non-porous powders by their sorption of stearic acid-1-carbon-14 from benzene solutions. Aliquots of the initial solution and of the solution in equilibrium with a sample were plated on chilled watch glasses and assayed by thin end-window Geiger counters. Specific surface areas obtained by this method for low-surface powders compared favorably with nitrogen-adsorption values (BET method). Results reported (in square meters per gram) are 21.1 for clay, 4.7 and 6.3 for two zinc oxides, 3.6 for alumina, 21.4 for calcium sulfate, 22.3 for nickel, 0.6 for glass beads, 6.5 for titania, 4.0 and 10.2 for two ferric oxides, 5.5 for zinc carbonate, 50.1 for manganese dioxide, 6.0 for maganous chloride and values of 4.0, 3.9 and 3.4 for zinc sulfide. The BET values for these powders were 19.8, 4.7 and 6.1, 3.4, 17.9, 24.9, 0.4, 7.7, 4.2 and 10.1, 4.9, 44.8, 5.8 and 3.7 m 2/g, respectively.