CHARACTERIZATION STUDY OF CARBONACEOUS MATERIALS - CALORIMETRIC HEAT OF ADSORPTION OF P-NITROPHENOL

Carbonaceous materials (six carbon blacks) were characterized in terms of their surface area, porosity, pore-size distribution, and surface chemistry. Using p-nitrophenol in aqueous solution as the adsorbate, t he calorimetric heat of adsorption was investigated in connection with the studied properties of the adsorbents. Techniques used were gas (N 2, CO2) and p-nitrophenol adsorption, mercury porosimetry, density mea surements, FT-IR, and microcalorimetry. The carbon blacks were include d in two groups depending mainly on their porosity. The chemical natur e of oxygen functional groups or structures was similar in all samples . Significant differences were observed in the concentration of surfac e oxygen groups. The heat of adsorption depended on the surface area a nd the microporosity of the samples. The density of oxygen groups was likely an important property in connection with the evolution of heat. The pore-size distribution of the adsorbents might also influence the heat of adsorption. When the amount adsorbed of p-nitrophenol and the heat of adsorption were expressed on a per unit surface area basis, g ood agreement with the FT-IR results was noted.