The below list represents only planned manuscripts. Some of these
manuscripts have not been received by the Editorial Office yet. Papers
submitted to MDPI journals are subject to peer-review.
Type of Paper: Review
Title: Recent Photocatalytic Applications in Belgium
Authors: Beeldens Anne*and Boonen Elia
Affiliation: Belgian Road Research Centre (BRRC), Woluwedal 42, B-1200 Brussels, Belgium; E-Mails: firstname.lastname@example.org; email@example.com
Abstract: The use of materials can influence to a large extent the environmental impact of traffic and road infrastructure. In this respect, photocatalytic concrete constitutes a promising technique to reduce a number of air contaminants such as NOx and VOC’s, especially at sites with a high level of pollution: highly trafficked canyon streets, road tunnels, urban environment, etc. Ideally, the photocatalytic material, titanium dioxide, is introduced in the top layer of the concrete pavement for best results. In addition, the combination of TiO2 with cement-based products offers some synergistic advantages, as the reaction products can be adsorbed at the surface and subsequently be washed away by the rain. A first application has been studied by the Belgian Road Research Centre (BRRC) on the side roads of a main entrance axis in Antwerp with the installation of 10.000 m² of photocatalytic concrete paving blocks. Although measurements on site did not give the expected results due to the configuration of the road surface, the laboratory results indicated a good efficiency towards NO and NO2 abatement as well as a good durability of this air cleaning characteristic. Special attention is given to the NO and NO2 content in the air, since they are for almost 50% caused by the exhaust of traffic and are at the base of smog, secondary ozone and acid rain formation. The great potential of this emerging technology is however hampered by the lack of uniform testing methods at European level (CEN) to assess, in an objective manner, the photocatalytic activity of these new building materials. For this purpose, laboratory research is undertaken at the BRRC to compare existing test methods, identify important influential parameters and draw up recommendations for future standards. Furthermore, the translation of laboratory testing towards results in situ remains critical to demonstrate the effectiveness in large scale applications. In this perspective, several new trial applications have recently been initiated in Belgium to assess the “real life” behavior. On the one hand, a field site was set up in the Leopold II tunnel of Brussels in the framework of the European Life+-project PhotoPaq. This major environmental project aims at demonstrating the effectiveness of photocatalytic materials on a realistic scale. To this purpose, photocatalytic materials have been applied on the walls and roof of the tunnel. Furthermore, in 2010 the INTERREG project ECO2PROFITstarted in cooperation with the regional development agency POM Antwerp. Here, a photocatalytic concrete with TiO2 in the top layer was applied for the construction of new pavements on industrial zones in Wijnegem and Lier (province of Antwerp). This paper first gives a short overview of the photocatalytic principle applied in concrete, to continue with some main results of the laboratory research recognizing the important parameters that come into play. In addition, some of the methods and results, obtained during the investigation of the existing application in Antwerp (2005) and during the implementation of the new realizations in Wijnegem and Lier, (2010-2012) and in Brussels (2012-2013), will be presented.
Type of Paper: Article
Title: Photoactive Porcelain Grès Tiles: An Industrial Product Combining Self-Cleaning, Anti-Pollution and Anti-Bacterial Properties
Authors: C.L.Bianchi, C. Pirola, G. Cerrato, S. Morandi, A. Carletti, F. Minozzi, V. Capucci
Abstract: Exposure to air pollution represents one of the most important health hazard for either mankind and all the ecosystem, pollution that is not present only outdoor but also indoor. To improve this situation, photocatalytic products and in particular photoactive porcelain slabs showed good performances in the degradation of the most common air pollutants, together with self cleaning and anti-bacterial properties. In this latter case even against antibiotic-resistant bacteria (MRSA).
In the preparation, a commercial micro-TiO2 (Kronos) was employed without using the traditional TiO2 nanomaterials in powdery form. Preparation, surface characterization and test of all the photocatalytic properties of the tiles will be here reported.
Type of Paper: Article
Title: Photocatalytic Activity of Nanocrystalline Anatase TiO2 Films with Controlled Degree of Preferred Crystal Orientation Prepared by dc Magnetron Sputtering
Authors: B. Stefanov and L. Österlund
Affiliation: Dep. Engineering Sciences, The Ångström Laboratory, Uppsala University, P.O. Box 534, SE-75121 Uppsala, Sweden
Abstract:Systematic deposition of transparent TiO2 thin films on glass slides were made by DC reactive magnetron sputtering at room temperature in an Ar/O2 flow at varying O2 partial pressure. The films were characterized by electron microscopy, and grazing incidence X-ray diffraction (GIXRD) complemented by Rietveld refinement. The as-prepared films were amorphous. After post-annealing in air for 1 h at 500 °C the films crystallized exclusively into the anatase phase exhibiting a nanocrystalline structure with mean grain size of 17–21 nm. The polycrystalline films showed a preferential facet orientation towards the highly reactive (004) plane, which was directly correlated with the partial O2 pressure employed in the synthesis, and could be tuned to be 0–38% of the total facet distribution as determined by GIXRD. Photocatalytic tests with methylene blue dye demonstrated that the (004) oriented films exhibited a higher reactivity, and shows that fine tuning sputtering conditions can be used to purposefully control the photocatalytic activity of TiO2 thin films.
Type of Paper: Article
Title: Antibacterial Activity of TiO2 Photocatalyst on E. coli
Authors: T. Verdier 1, M. Coutand 1, A. Bertron 1 and C. Roques 2
Affiliation: 1 Université de Toulouse, UPS, INSA, LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135 Avenue de Rangueil, F-31077 Toulouse Cedex 04, France
2 Université de Toulouse, UPS, LGC (Laboratoire de Génie Chimique), Dép. BioSyM, LabMI, FR Pharmacie - 35 rue des Maraîchers, 31062 Toulouse Cedex 09, France
Abstract: The production of airborne particles (spores, allergens, toxins, etc.) by microorganisms inside buildings plays a major role in the degradation of indoor air quality and contributes to Sick Building Syndrome (SBS). These microbial polluting agents are responsible for various skin and respiratory diseases of occupants and the resulting social and economic consequences are considerable. Indoor building materials are among the main proliferation environments of these microorganisms. Photocatalytic coatings could be a way to prevent microbial proliferation or, at least, to significantly reduce the amount of microorganisms that grow on indoor building materials. Previous works involving TiO2, photocatalytic particles have already shown the inactivation of bacteria by the photocatalysis process with an inactivation rate over than 99.9% after 30 minutes of UV irradiation. In the first minutes, oxidation of the outer membrane by the reactive species caused damages that are not sufficient to lead to the death of cells but can contribute to it. It should be noted that various methodologies were carried out and lead to different results in the photocatalytic antibacterial activity: the amount and implementation of TiO2, the intensity and duration of light irradiation, the amount of cells in the inoculum, the quantity of water, etc. can contribute to the observed differences. This paper aims to study the inactivation of Escherichia coli bacteria by photocatalysis of TiO2 nanoparticles and focuses on various parameters that significantly influence antibacterial activity. The antibacterial activity of TiO2 was evaluated (i) in slurry with physiological water and (ii) in a drop deposited on a glass plate, under UV irradiation. Controls have been carried out with samples under UV irradiation without TiO2 and in the dark with/without TiO2. The tests on the glass plate were based on the standards ISO 27447 and JIS Z 2801, with adjustments in several parameters such as the quantity of water and the contact between nanoparticles and cells.The results showed varied antibacterial activities of TiO2 on E. coli in the drop-type experiment; the use of a transparent film that covered the inoculum and forced the contact between TiO2 nanoparticles and bacterial cells notably increased the activity. The study also focuses on the antibacterial activity of semi-transparent coatings, formulated using TiO2 nanoparticles. Further works will be conducted to investigate on the antifungal activity and the resistance to the formation of microbial biofilms.
Type of Paper: Review
Title: Development of Novel Photocatalysts and Their Application for Water Treatment: A Review
Authors: Sushil R. Kanel and Mark N. Goltz
Affiliation: Department of Systems Engineering and Management, Air Force Institute of Technology, 2950 Hobson Way, Wright-Patterson AFB OH 45433, USA
Abstract: There are different types of photocatalysts used for Advanced Oxidation Processes (AOPs) to treat water. In this review, we focus on synthesis and application of nano titanium dioxide (TiO2) for water treatment. The TiO2 is used to catalyze the oxidation of organic and inorganic contaminants in the presence of light by producing hydroxyl radicals, superoxide radicals, and holes (h+). Here we evaluate the progress that has been made using nano TiO2 and surface modified nano TiO2 for energy efficient water treatment. The mechanism and kinetics of using TiO2 to photocatalyze different contaminants will be discussed.
Type of Paper: Article
Title: Photocatalytic Activity and Stability of Porous Polycrystalline ZnO Thin-Films Grown via a Two-Step Thermal Oxidation Process
Authors: James C. Moore1, Robert Louder1 and Cody V. Thompson1,2
Affiliations: 1 Department of Chemistry and Physics, Coastal Carolina University, Conway, SC 29528, USA
2 Research & Development Laboratory, Wellman Engineering Resins, Johnsonville, SC 29555, USA
Abstract: The photocatalytic activity and stability of thin, polycrystalline ZnO films was studied. Photo-degradation of organics at the ZnO surface results from the creation of highly oxidizing holes and reducing electrons induced by ultraviolet (UV) light. Therefore, the efficiency of electron-hole pair formation is of critical importance for self-cleaning and antimicrobial applications with these systems. In this study, ZnO thin films were fabricated on sapphire substrates via DC sputter deposition of Zn-metal films followed by thermal oxidation at several annealing temperatures (300, 600, 900, and 1200C). Characterization of the resulting ZnO thin films through X-ray diffraction, atomic force microscopy, and photoluminescence indicates that decreasing annealing temperature leads to smaller crystal grain sizes and increased UV excitonic emission. The photocatalytic activities of the films were also characterized by measuring the efficiency of degradation of Rhodamine B dye in solution. The films oxidized at lower annealing temperatures exhibited higher photocatalytic efficiency, which is attributed to the increased effective surface area and optical quality. Photocatalytic activity is also shown to depend on film thickness, with decreasing activity observed for decreasing thickness. The stability of these films with respect to photo-degradation of Rhodamine B is also studied. Specifically, decreasing activity is shown to be the result of a decrease in film thickness with exposure time.