Indoor Photocatalytic Paints: Air Decontamination and Mold Growth Control Assessment

O. M. ALFANO; FEDERICO SALVADORES; MARÍA DE LOS MILAGROS BALLARI; SIVIA MERCEDES ZACARIAS

Hong Kong

Congreso; The triennial International Symposium on Nanotechnology in Construction (NICOM); 2018

Nano and Advanced Materials Institute Limited (NAMI)

Photocatalytic building materials containing TiO2 were extensively studied for outdoor applications using solar radiation. Nowadays, the market offers a wide variety of these materials with self-cleaning and air purification functionalities. However, visible light heterogeneous photocatalysis applied in indoor construction materials was less developed. The objective of this work is to investigate the photocatalytic performance of modified TiO2 with UV-visible light absorption replacing the pigments in indoor wall paint formulations. To achieve this goal two model indoor air pollutants were selected: a VOC and an environmental mold. From one hand, the photocatalytic oxidation of acetaldehyde in gas phase was carried out using different photocatalytic paint formulations varying the type of modified TiO2 (carbon doped, nitrogen doped and undoped one) and its amounts (12-18% w/w). The air decontamination process was conducted using regular indoor light in a flat plate laboratory scale photoreactor and in a chamber bench scale photoreactor simulating a room. In the lab scale system the optimal photocatalytic paint formulation for the acetaldehyde oxidation was determined, being the paint containing 18% w/w carbon doped TiO2 the best one. Then, this paint formulation was tested in the reaction chamber with more closeness to its final application and varying the main environmental conditions that affects the photocatalytic process: air change rate, irradiance, relative humidity and initial acetaldehyde concentration. On the other hand, the fungicide effect of the optimal paint formulation for the air pollutant treatment was evaluated. The conidia of Aspergillus niger was selected as the model microorganism and the inactivation tests were performed under UV and visible light. The photocatalytic paint and blank surfaces under visible light showed the same fungi inactivation due to a photochemical reaction. Nevertheless, the photocatalytic process took places when samples were irradiated with UV light finding a significant higher conidia inactivation on the photocatalytic paint. However it was fond that both radiation (visible and UV) only with the photocatalytic paint produce an effect over the conidia that generate a progressive damage, which continue even after the irradiation assay was been finished. This confirm the power of fungi growth control of this paint.