No abstract

Adsorption Isotherms of water vapor on Mobil Sorbead R silica gel were obtained gravimetrically at 301, 310, and 326 K up to the saturation pressure. The equilibrium data were used to calculate the heat of adsorption at constant adsorbent loading. The magnitude of the heats of adsorption Is Indicative of physical adsorption. The BET method was also used to calculate the monolayer capacity and the surface area. Straight lines were obtained when applying the BET model over the relative pressure range 0.05-0.40. The equilibrium adsorption data were also correlated by the modified Polanyl potential theory.

Adsorption studies of a homogeneous series of dlcarboxyllc acids were performed at 5 and 40 °C, with oxalic, malonic, and succinic acids being adsorbed from dilute aqueous solutions onto activated carbon. Experimental data were compared with the calculated equilibrium uptakes as predicted by three different models: Freundllch Isotherm, Langmuir Isotherm, and the potential theory. A single generalized characteristic curve for these dlcarboxyllc acids was obtained In accordance with the potential theory. The average errors between the values calculated by the potential theory and the experimental data ranged from 1.80% to 5.44%. In this study the potential theory provided a better fit to the experimental data than did either the Freundllch or Langmuir Isotherm equations.

The adrorptkn of NH, on Davkon rWca gel was studled at 298, 313, and 333 K by wlng a packed bed method.Equiliklwn koth" were calculated from the adsorption data and were modeled by the Langmuh and mod#led Polanyl potentla1 equathw. ExperkrrcMtsl breakthrough curves were obtalned for dx concentrattons of NH, In dry helium gas at each temperature. The Isosterk heats of adrorption were also cakulated at three ad8orbent loadand were found to be nearly Mepmdmt of loadlng. A calculated heat of ackorpllon of the same order of msgnlhrde as the heai of condenmtkn lndkated that the adeorptlon was prhnarlly due to phydcal forces.

A static experimental apparatus has been used to measure vapor-liquid equilibria for aqueous systems containing ammonla and carbon dioxide. Both phases were sampled and analyzed using gas-liquid chromatography. For aqueous mrxtures of ammonia-potassium nitrate and ammonia-potassium sulfate, measurements were made at 100 and 150 OC to examine the effects of salts at elevated temperatures. Some data are also given for the NH3/C02/H20 system at 100 and 150 'C. These and other recent experimental data were used to update the computerized molecular-thermodynamic correlation of Edwards et al. for sour-water phase equilibria, as required for water-pollution abatement.