This paper presents a method for removing organic dyes by sorption and photocatalytic processes on a bentonite bed modified with ZnO-CuO nanocomposite. The effect of the initial dye concentration and temperature on the amount of dye removed from the solution was investigated. The results obtained at equilibrium state allowed us to determine the equilibrium and kinetic models and the thermodynamic parameters for the studied processes. The Langmuir isotherm is the best model for describing the equilibrium processes for both sorption and sorption with photocatalysis. In terms of kinetics, both processes are accurately described by the pseudosecond order model, which demonstrates the chemical nature of sorption. Due to the negative ΔG values calculated from the tests, it was found that the studied processes are spontaneous. It was possible to obtain a better degree of purification of the dye solution using combined sorption and photocatalysis compared to the sorption process itself.
