1 The adsorption of ammonium ions by natural zeolite and Al 2 O 3 under static conditions has been investigated. The reason for changing the investigated solution pH during adsorption of ammonium ions on Al 2 O 3 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 Al 2 O 3-NH 4 Cl-H 2 O have been carried out. It was established that the adsorption of ammonium with aluminum oxide occurs via the mechanism of physical adsorption.

In the paper, the assessment of the impact of heavy metals on water objects, namely copper and chromium was performed, and the methods for their neutralization were defined. A scientifically grounded method for the selection of natural zeolite for the purification of wastewater from heavy metals has been developed, provided that they are jointly present. The physicochemical characteristics of two metals related to heavy metals are presented: copper and chromium. The methods for determining the sorption capacity of natural zeolite for copper and chromium compounds, as well as the methods of analytical control of the wastewater components were presented. The results of the experimental studies on the combined adsorption of copper and chromium cations by natural zeolite under static conditions were presented. The changes in the chemical composition of the zeolite surface as a result of heavy metal sorption have been investigated. The influence of the nature of the ions and the pH of the adsorption medium on the selectivity of the heavy metal ions extraction by zeolite was analyzed. A diagram of the composition of the solution, depending on the pH values, was constructed. The pH of the beginning of deposition of the corresponding heavy metal hydroxides on the zeolite surface was calculated. While analyzing the results of experimental studies on the combined adsorption of copper and chromium ions, it was found that the copper ions are significantly better adsorbed by the sorbent than the chromium ions. Despite the same concentration of the chromium and copper ions in solution, Cu 2+ is extracted selectively. As can be seen from the results of experimental studies, the concentration of copper on the surface of the sorbent increases from 0.628% mass at a concentration of 0.01 g/dm 3 to 47.380% mass at a concentration of 1 g/dm 3 . The studies on the static activity of clinoptilolite for the copper and chromium ions indicate a simultaneous mechanism of the process, which involves ion exchange and physical adsorption. The concentration of the chromium ions on the surface of the sorbent after adsorption depends on the increase of the concentration of Cr 3+ in the original solution to a lesser extent. The results of the studies on the combined adsorption of the Cu 2+ and Cr 3+ ions indicate the possibility of their chromatographic separation, which makes their further use possible.

The results of the research of the adsorption capacity of a number of sorbents of natural and synthetic origin for ammonium ions have been clustered. The natural zeolite of the Sokyrnytsia deposit, a synthetic sorbent based on the fly ash of Dobrotvir state district heat power plant, Al 2 O 3 , SiO 2 , as well as some types of soil: sandy soil, black soil, and clay were used in the research. Equations describing the regularities of adsorption processes depending on the type of sorbent were obtained. According to the obtained dendrograms, two main clusters of sorbents were identified. The statistical parameters of the process and the significance of the obtained results were calculated. The coefficient of determination of the experimental data was 0.67-0.99, the standard deviation was 0.017-0.026.

The dynamics of the adsorption process in the fixed-bed column was experimentally studied on the example of the system natural zeolite - water solution of copper salt with low concentrations, which are characteristic for wastewater treatment processes from toxic contaminants. The initial curves of the adsorption process for the height of the sorbent layer of 5 and 7 cm were constructed. The equilibrium of such processes can be described by Henry's linear equation. The adsorption process in the layer consists of two stages, which are examined in the study. The first stage is the formation of concentration front and the second one – its moving. The sum of the time of the first and second stages is the total adsorption time, which is determined before breakthrough time. The first stage of adsorption is mathematically formulated by the differential equation of molecular diffusion with a boundary condition of the first type. The second stage is supplemented by the balance equation, which takes into account not only the change of concentration in time, but also in the vertical coordinate and determines the time of movement of concentration front to breakthrough time. A mathematical model of the adsorption process in a fixed-bed column has been developed. Experimental data and theoretical calculations were compared. The results of statistical calculation of research results showed a satisfactory convergence of experimental and theoretical data.

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