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In this work the photocatalytic activity of paints incorporating commercial titanium dioxide for outdoor nitrogen oxide (NO) photoabatement is assessed. The paint acts as a 3D support of the photocatalyst and thus allows a larger amount of TiO2 nanoparticles to absorb light and to contact with pollutants, when compared with a 2D photocatalytic surface. NO conversion and selectivity towards nitrites and nitrates were determined according to the standard ISO 22197-1:2007 (E).Paint coatings were formulated and tested under laboratory and outdoor conditions. The best paint formulation incorporates CristalACTiV TM PC500 photocatalyst from Cristal and calcium carbonate extender, presenting a NO conversion of ca. 70% and a selectivity of ca. 40% under laboratory conditions. The same photocatalyst but characterized in the form of an optically thick film of compressed powder presented ca. 95% and 45% of conversion and selectivity, respectively. Under the real-outdoor conditions, the best performing paint showed a NO conversion of about 95%.

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26n-Decane is a saturated long-chain hydrocarbon, belonging to the family of the 27 volatile organic compounds (VOCs), which is persistently present in indoor air of several 28 industrial closed facilities. Due to the VOCs environmental impact, all efforts that have 29 been made during the last decades to degrade this kind of air pollutants are extremely 30 important. Accordingly, the present paper reports n-decane photooxidation studies carried 31 out in an annular photoreactor under simulated solar irradiation and employing a catalytic 32 bed made of cellulose acetate monoliths coated with a photocatalytic paint. The influence 33 of the feed flow rate, n-decane concentration, relative humidity, and incident irradiance 34 on the n-decane degradation kinetics was assessed. Within this work, n-decane 35 photodegradations higher than 90% were achieved, depending on the experimental 36 conditions. Additionally, a phenomenological reaction rate model of the n-decane 37 photocatalytic oxidation was proposed and assessed. The proposed model assumes that 38 n-decane and water molecules compete for different active sites on the catalyst surface. 39Finally, despite the high n-decane photodegradation achieved, reaction by-products were 40 identified and, based on these compounds, a reaction mechanism was formulated. 41 42

The photocatalytic degradation of cyanotoxins in aqueous solutions using slurry suspensions of TiO2 implies a post-filtration step to retain the photocatalyst. In this work, 2D and 3D TiO2 thin films sup-ported in inert surfaces was proposed for the solar photocatalytic removal of cyanotoxins microcystin-LR (MC-LR) or cylindrospermopsin (CYN) in distilled and natural water under neutral pH conditions. The photocatalytic experiments were performed in a lab-scale tubular photoreactor with a compound parabolic collector (CPC) using simulated and natural solar radiation. The tubular photoreactor was packed with transparent cellulose acetate monoliths (CAM) coated with a P25 paste or sol-gel 2D TiO2 film or with a photocatalytic 3D TiO2-loaded exterior paint (PC500, VLP7000 and P25). The efficiency of the TiO2 photocatalytic system in the presence of hydrogen peroxide was also assessed. PVC or glass tubes and glass spheres, coated with a photocatalytic 3D TiO2-loaded exterior paint, were also tested as inert surfaces. The supports used in this work were chosen according to some characteristics, such as cost, surface resistance, surface area and transmissibility to UV radiation. The 2 toxins MC-LR and CYN were purified from Microcysts aeruginosa and Cylindrospermopsis raciborskii cultures, respectively. The photocatalytic system P25-CAM/H2O2 can be considered the most effective process, considering the cyanotoxins removal efficiency, the cost and the simplicity of the preparation.

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