Photocatalytic paints for NOx removal: Influence of various weathering conditions

Three commercial exterior photocatalytic paints, from STO, Boysen and Graphenstone one In-house paint, are tested using the NO ISO; FT-IR analysis shows that all paints contain an acrylate binder, but also siloxane and/or silicate binders. All exhibit little or no activity (for removal) without weathering. The only activated by ‘standard’ weathering, i.e. a continuous cycle of UV irradiation (0.76 mW cm-2, 8 h at 50 °C) plus condensation (4 60 °C). In contrast, STO ‘condensation-only’ weathering water droplets °C for ca. 56 h. This is first report efficacy latter type vs time profiles paint show it almost exclusively condensation-only which fast (60% maximum within h) produces film active durable. standard relatively slow (only 25% after 24 involves oxidation binder; as consequence not very Irrespective method activation, little, no, NOx removal towards end 5 period ISO, due to accumulation surface HNO3, promotes conversion NO2.