Indoor Photocatalytic Paints: Air Decontamination and Mold Growth Control Assessment

BALLARI, M.M.; SALVADORES, F,; ZACARIAS, S.M.; ALFANO, O.M.

Simposio; Symposium on Nanotechnology in Construction (NICOM6); 2019

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. On the 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, first in a flat plate laboratory scale photoreactor, and later 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 varying the main environmental conditions that affect 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 was evaluated. The conidia of Aspergillus niger was selected as the model microorganism and the inactivation tests were performed under UV and visible light. It was found a progressive conidia damage on the photocatalytic paint surfaces under both illumination types, which can continue even after the irradiation tests. The results reveal the air purifying and fungi growth control power of photocatalytic paints under indoor conditions.