DETERMINATION OF SPECIFIC SURFACE AREAS OF DISPERSED MATERIALS . COMPARISON OF NEGATIVE ADSORPTION METHOD WITH SOME OTHER METHODS

In this paper specific surface areas are reported of dispersed silver iodide, hematite, and silica that have been measured using six different methods including the negative adsorption method, based on the expulsion of co-ions. Both the BET and negative adsorption give internally consistent results, but in the case of silver iodide negative adsorption areas are consistently about a factor of 3.3 higher than BET areas. Consideration of the available experimental evidence suggests that at least in this case the negative adsorption area should be preferred over the BET area when one is concerned with the area of materials dispersed in aqueous solution. © 1968, American Chemical Society. All rights reserved.