ADSORPTION OF AMMONIA WITH ACTIVATED COAL AG-3

Abstract

The problem of NH3 extraction from wet gases and returning it to the process may take place in the technologies which use aqueous ammonia solutions. The extraction of non-ferrous metal oxides forming soluble ammoniates from industrial wastes with the solution of ammonium chloride and ammonia in water is an example of such technologies. The oxides of non-ferrous metals are then precipitated, driving the mixture of water vapor and ammonia off the solution. Waste purification reduces the pollution of natural water resources and expands the raw material base of metallurgy of copper and zinc. To return NH3 to the waste treatment it is efficient to use adsorption of ammonia from the gas-vapor mixture. The silica gel used in ammonia plants is not applicable to absorption NH3 from wet gases. The data on the adsorption NH3 from the gas-vapor mixture with hydrophobic activated coals are not sufficient for practical purposе. The dependence of the equilibrium adsorption capacity of activated coal AG-3 on ammonia wapors on their partial pressure at 0.1−15 kPa and a tempеrature of 288−323 K in the sorption of ammonia from wet gases is studied with a dynamic method. The micropore volume of the coal samples is equal to 0.31±0.02 cm3/g. The presented equation provides the calculation of the sorption capacity of coal in the studied range of adsorption parameter change with an average error less than 5% for each isotherme. The heat of adsorption is equal to 37 -39 kJ/mol which is larger than the heat of condensation of ammonia vapors by about 20 kJ/mol, which is typical for physical adsorption. During the regeneration of the coal which absorbed the ammonia the adsorption capacity was stable.