The removal of acetaldehyde is performed by a procedure based on the international standard ISO 22197-2:2019 "Test method for air-purification performance of semiconducting photocatalytic materials - Part 2: Removal of acetaldehyde". According to the standard, acetaldehyde gas is adsorbed on the surface of the photocatalyst and after irradiation the pollutant is broken down into more harmless compounds. The experimental device shown in Figure 1 is used to record the acetaldehyde concentration.