The Difference between Iodine Number and Nitrogen Surface Area Determinations for Carbon Blacks

Abstract

Abstract The iodine number furnishes surface area values in disagreement with the NSA technique in the case of disordered carbon i.e., lower than NSA in case of high oxygen content (more than 2%), but higher for low oxygen content (less than 1%). Because carbon blacks are solids which exhibit graphitic structure, some milled graphite samples, were taken as model materials and analyzed. Surface area was determined by using both NSA and N≩I2 techniques, and the difference between the results given by the two techniques were observed and related to the microstructure, which was analyzed by using X-ray diffraction, Raman spectroscopy, and the oxygen content was measured by using elementary analysis. Two different models of iodine adsorption have been proposed, respectively, for the graphitic parts of the graphite grains and for the disordered part of the grains. An analytical relationship between the differences of iodine and nitrogen surface area values, microstructure and oxygen content was proposed and successfully tested. The same relationship was applied to some commercial and experimental carbon black with good results.