ESN: can environmental coatings really purify the air? You may think more!

A study by Chinese and French scientists raised the issue of the effectiveness of paints that can prevent and control air pollution Research shows that when paint decomposes some pollutants, they also produce and release other toxic compounds Air pollution in most cities of the world is not optimistic Automobile exhaust and thermal power plant exhaust are the main sources of organic pollutants Titanium dioxide as photocatalyst can degrade these organic pollutants When TiO2 nanoparticles are exposed to UV light, they can oxidize organic compounds in the air When TiO2 nanoparticles are added to the coating, they become photocatalytic coatings Some photocatalysis materials have been commercialized as environmental protection coatings, however, they are doubtful for the overall improvement of air quality a) The photocatalytic coating contains TiO2 nanoparticles c) With the coating aging, titanium dioxide nanoparticles will be released b) Ultraviolet radiation activates TiO2 nanoparticles, which degrade VOCs in the environment and the organic matter in the paint, and release new VOCs into the air (source: Environmental Science: nano) the sasho gligorvoski team of the Chinese Academy of Sciences found that photocatalytic coatings release a large number of nanoparticles and volatile organic compounds (VOC) in their life cycle, so as time goes by, the VOC in the room keeps accumulating, which will make the indoor air become very bad The amount of VOC released from the original and aged photocatalytic coatings (source: Environmental Science: nano) scientists used xylene to evaluate the ability of TiO2 nanoparticles to remove VOC from the air The results showed that they hypothesized that UV irradiation activated nanoparticles, leading them to release hydroxyl radicals These free radicals actively capture and decompose VOC in the air and toxic organic pollutants in the paint Therefore, when xylene is removed from the coating, a series of new VOCs will be generated in the reaction process, which will degrade the surface of the coating and release nanoparticles Formaldehyde, which is classified as a carcinogen, has been identified as one of the new VOCs Photocatalysis coating only needs sunlight or environmental lighting to work, so it is considered as a simple and sustainable purification technology However, the questions raised by the sasho gligorvoski team challenge the effectiveness of titanium dioxide photocatalytic coatings as a cleaner for improving urban and indoor air quality Delphine truffier Boutry, a commentator at the University of the Alps in Grenoble, France, said: 'we still need a lot of efforts to really achieve the use of photocatalytic coatings to improve air quality Nishith Verma, a catalyst expert at the Indian Institute of technology, Kanpur, commented that this study is of great significance from the perspective of controlling indoor pollution of commonly used photocatalytic coatings Metal nanoparticles and several VOCs are carcinogenic Manufacturers of photocatalytic coatings can consider adjusting the synthesis route to minimize the degradation of photocatalytic coatings Bernd Nowack, a nanoparticle environmental risk assessment expert at the Swiss Federal Laboratory for materials science and technology, added: "only a large-scale study can show whether photocatalytic paint really has an impact on air pollution It will be very important to establish the corresponding catalytic reaction model " Gligorvoski's team hopes to find a way to prevent the release of harmful substances from photocatalytic coatings by using safer nanoparticle manufacturing methods, and work closely with coating manufacturers to achieve this goal Therefore, if we hope to use photocatalysis coating - environmental protection coating to purify the air, it is only a drop in the bucket Paper link: http://pubs.rsc.org/en/content/articlelanding/2017/en/c7en00467b ා! Divabstract