Photocatalysis is a chemical reaction mediated by light, humidity and by photocatalysts, such as titanium dioxide (TiO2). It plays an important role in the oxidation of pollutants, biological toxic agents, and volatile organic molecules. Surfaces coated with photocatalysts could therefore play an important role in improving air quality in indoor and outdoor environments. The current ceramic tile coating process entails spraying a mixture of TiO2 powder (micrometre and nanometre-sized particles), water and silica-based additives over the tile surface in a heatingcycle (up to 680C). Subsequently, the surface is brushed and washed with water, in order to remove excess titanium dioxide particles, and to achieve a homogeneous surface. The process requires the consumption of large quantities of water and energy, while about 70% of the TiO2 powder is lost from input to final deposition. Although titanium dioxide is chemically inert, recent studies though not yet conclusive suggest that TiO2 nanoparticles may be potentially harmful for human health, especially for workers in close and prolonged contact with such powders.
LIFE DIGITALIFE set out to produce photocatalytic surfaces for the ceramic tile industry using digital printing technology. The new process promised to drastically cut the amount of titanium dioxide used and disposed of as waste as well as significantly reducing energy and water use. The technology was to be based on suitably designed print-heads, using an ink based on solvents, TiO2, and additives (e.g. silicon-based powdersto facilitate surface vitrification), able to coat a wide range of tile surfaces (up to 1.5 by 3 m). The use of a water-based ink instead of a solvent-based one was expected to further reduce the environmental impact of the process. The beneficiary planned to validate its results and widely disseminate them in order to raise awareness of sustainable manufacturing, and of the positive environmental impact of eco-active tiles.
The DIGITALIFE project designed and optimised new inks for digital printing of ceramic tiles, built an industrial-scale pilot plant, tested and optmised the digital printing process and analysed performance in terms of environmental benefits. This showed that the new process cut TiO2 consumption by 50% and almost totally eliminated waste, since the titanium dioxide powder is more adherent to the tile surface. It uses micro-sized TiO2 instead of more harmful nano-sized particles, leading to a healthier work environment. The pilot plant reduced energy consumption by 44% in comparison with the industry standard. Water consumption was cut by 95% during tile manufacturing, while from cradle to gate, the water footprint of the new printing process is about 30% lower than the traditional technique. Tests confirmed that the new tiles retain photocatalytic properties, which can degrade atmospheric pollution from NOx, and volatile organic compounds, including formaldehyde. One unforeseen benefit was that the tiles alsohave anti-bacterial properties, even against the MRSA bacteria. The success of the project has encouraged the coordinating beneficiary to invest more than 7 million euros in a full-scale (220000 sqm per year) industrial plant to bring the new tiles and related technology to market. It expected to sell hundred thousands square metres of the photo-catalytic tiles in 2018 and even more in the following years, creating the possibility of sale force expansion. The new tiles will be installed in hospitals in Europe and Singapore, and in commercial centres in Mexico City and China. The environmental benefits of the new process mean that this LIFE project can contribute to achieving the objectives of the Clean Air Policy Package, Climate and Energy Package, Water Framework Directive, Waste Framework Directive and the new EU One Health Action Plan against antimicrobial resistance. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).