Photocatalytic activity of titanium dioxide nanoparticle coatings applied on autoclaved aerated concrete: effect of weathering on coating physical characteristics and gaseous toluene removal.
Autoclaved aerated concrete has been coated by TiO(2) nanoparticles through a dip-coating (DC) and a novel vacuum saturation (VS) method to investigate the weathering resistance and gaseous toluene removal potential of both coating types. The effect of intensive weathering - corresponding to a period of about 25 years - on the coating characteristics was studied in terms of TiO(2) content, coating thickness and color changes. Toluene removal was investigated in a lab-scale flow-through photoreactor at 24°C and 52% relative humidity, and results obtained immediately after application of the coatings and after two weathering stages were compared. Weathering of the DC and VS coated samples resulted into a decrease of the coating layer thickness of more than 98%, confirmed by a decline in TiO(2) content by more than 99% and 93%, respectively. Surprisingly, toluene removal efficiencies before and after weathering kept constant at about 95% for both coating types, corresponding to an elimination rate of 60-70 mg/(m(2)h) at an initial toluene concentration of 15 ppm(v) and a gas residence time of 3 min. Increasing the toluene load by applying higher toluene inlet concentrations (up to 35 ppm(v)) and lower gas residence times (1 min) did decrease the toluene removal efficiency to 32-41%, but elimination rates increased up to 214 mg/(m(2)h), being a factor of 1.6-4.5 times higher than reported in recent work.
Magnel Laboratory for Concrete Research, Department of Structural Engineering, Faculty of Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent, Belgium.
Anibal
A
Maury-Ramirez
Kristof
K
Demeestere
Nele
N
De Belie
D000393:Air Pollutants / Q000737:chemistry* / Q000528:radiation effects; D002384:Catalysis; D003252:Construction Materials; D053758:Nanoparticles; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014887:Weather
D000393:Air Pollutants; C009495:titanium dioxide; D014050:Toluene; D014025:Titanium