Dynamics of Adsorption of Copper Ions in Fixed-Bed Column and Mathematical Interpretation of the First Stage of the Process

Abstract

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.