Photocatalytic properties of coating materials enriched with bentonite/ZnO/CuO nanocomposite

Highlights: • Bentonite/ZnO/CuO-based coating materials have photocatalytic properties. • The addition of copper(II) oxide increases zinc oxide photocatalytic activity. • Impurities deposited on the photocatalytic coatings can be gradually degraded. The ZnO nanoparticles modified with specific metal oxides exhibit high photocatalytic activity and are used as building material additives and active coating components. The nanocomposite of bentonite/ZnO/CuO as photocatalytic additive in coating materials was synthesised and verified in this study. The test results confirmed that the obtained hybrid system and enhanced paint and plaster with nanocomposite had photocatalytic properties. Sorption and photocatalytic properties of the nanocomposite were influenced by time and the initial concentration of the removed dye. For the plaster coating material, the highest dye removal efficiency was 2.45 mg/g. The modified paint showed the highest efficiency of 12.49 mg/g. The efficiency values are for materials with 5% bed content in relation to its dry mass, at the initial concentration of the dye (200 mg/dm³). The photocatalytic activity of hybrid systems and doped coating materials was analysed by the sorption process and sorption with the presence of ultraviolet radiation (λ = 365 nm). The character of both the sorption process and sorption with photocatalysis was consistent with a pseudo-second-order equation, its type was chemical. The sorption equilibrium in both processes was best described by Freundlich's isotherm.