The ZnSe nano-film was prepared to obtain novel nano-particles for removing Congo red (CR) dye. A ZnSe nano-film with a thickness of 0.8 µm was fabricated using the vacuum evaporation technique. The average crystallite size of the ZnSe nano-film crystallites was 0.38 nm. The extinction coefficient and refractive index exhibit wavelength dependence at lower wavelengths, whereas the reflective index value remains constant (=1.56) at wavelengths above 500 nm. To assess the dye removal efficiency, UV-visible spectroscopy was used to compare the dye concentration in an aqueous solution, both in the presence and absence of the ZnSe nano-film. The optimized effective parameters for dye removal were achieved with 60% removal at 90 minutes of contact time and 71% removal at pH 7. The results indicate that the reaction is spontaneous and exothermic, with the adsorption process leading to increased disorder. Kinetic and isotherm model analyses revealed that the Pseudo-second-order and Langmuir models best describe the adsorption behavior, with correlation coefficients (R²) approaching 1. Under optimal conditions, the maximum adsorption capacity was determined to be 2.98 mg/g for Congo Red removal.
