ANALYSIS OF AMMONIA ADSORPTION ON SILICA-GEL USING THE MODIFIED POTENTIAL-THEORY

The adsorption of NH//3 on Davison silica gel was studied at 298, 313, and 333 K by using a packed bed method. Equilibrium isotherms were calculated from the adsorption data and were modeled by the Langmuir and modified Polanyi potential equations. Experimental breakthrough curves were obtained for six concentrations of NH//3 in dry helium gas at each temperature. The isosteric heats of adsorption were also calculated at three adsorbent loadings and were found to be nearly independent of loading. A calculated heat of adsorption of the same order of magnitude as the heat of condensation indicated that the adsorption was primarily due to physical forces.