ABSTRACT
This work explores surface interactions between stabilized gypsum and nitric oxide. Gypsum is a common air-borne mineral particulate that has a potential two-fold relationship to the air pollution problem: as a particulate pollutant and as a catalyst or adsorbent for pollutant gases. Nitric Oxide is found in stack gases and automotive exhausts. Isotherms of nitric oxide adsorbed on stabilized gypsum were studied at 24 degrees C, 0 degree C, and -78 degrees C. Coverages were related to a monolayer based upon a surface area of 17.0 m2/g as determined from a nitrogen adsorption isotherm and the B.E.T. method. Multilayer coverages containing both reversible and irreversible adsorption were observed for nitric oxide adsorbed on stabilized hydrated calcium sulfate. An irreversible coverage of 41% at 24 degrees C and 61% at 0 degree C of the nitrogen monolayer was observed for nitric oxide adsorbed on hydration stabilized gypsum. The heat of adsorption at zero coverage was found to be 80.4 kJ/mol for nitric oxide on stabilized hydrated calcium sulfate for the irreversible adsorption and 7.5 kJ/mol for the reversible adsorption.
