The adsorption of ammonium ions by natural zeolite and Al2O3 under static conditions has been investigated. The reason for changing the investigated solution pH during adsorption of ammonium ions on Al2O3 has been grounded. A phase diagram of the twocomponent system has been constructed and the composition of the adsorption system in the state of equilibrium has been determined. The thermodynamic calculations of the adsorption system Al2O3–NH4Cl–H2O have been carried out. It was established that the adsorption of ammonium with aluminum oxide occurs via the mechanism of physical adsorption.
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