Application of TiO2 thin films coated on pet by high power impulse magnetron sputtering for water treatment

• Autor(a) principal: Rafaela Brito Portela Marcelino
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/53383
• topic: Surface engineering; Band-gap engineering; Carbendazim; Caffeine; Photocatalysis; Engenharia sanitária; Meio ambiente; Cafeina; Carbendazim; Fotocatalise

Solar photocatalysis is a promising and environmentally sustainable process of water and wastewater treatment, as it uses solar radiation photons as the driving force for the pollutant degradation process. One of the greatest drawbacks in implementing this type of process is the separation and recovery of powdered catalysts. In this context, the use of catalysts immobilized on low-cost solid materials, such as organic polymers, may be an interesting solution. Recent advances in the field of surface engineering, such as the High Power Impulse Magnetron Sputtering (HiPIMS) process, have proven able to deposit photocatalytic active coatings directly on flexible polymer substrates (polyethylene terephthalate - PET, for example) in a single phase process. In this sense, this project aims at the application of photocatalytic surfaces formed by TiO2 thin film coated on PET sheets for the solar treatment of water contaminated with two model pollutants: caffeine (central nervous system stimulant and an indicator of anthropogenic pollution) and carbendazim (toxic and recalcitrant fungicide widely used in Brazil). This work includes the partnership with Manchester Metropolitan University for the deposition of thin photocatalytic film on PET sheets; the characterization of the material regarding its elemental composition (EDS, EELS) as well as its crystallographic (Raman), morphological (SEM, STEM), textural (SEM, STEM, AFM), optic (UV-Vis transmittance) and tribological (profilometry and hydrophilicity) properties; the assessment of its photocatalytic properties against model pollutants in bench scale using UV-A/Vis reactor and solar irradiation simulator; and the study of the integration of photocatalytic materials into semi-pilot scale water treatment reactors (CPC and RPR). The obtained results indicate that the photocatalytic surfaces, in the presence of a natural photosensitizer (turmeric), were able to minimize the concentration of contaminants of emerging concern (caffeine and carbendazim) by up to 40% in aqueous solutions and that the catalytic surfaces can be reused without significant loss of activity. The results also showed organic matter mineralization of up to 79% and the reduction of acute toxicity to Aliivibrio fischeri from treated pollutants solutions, which eliminates the possibility of formation of degradation by-products more toxic than the original pollutants. In addition, the study of reactive oxygen species showed the prevalence of the electrogenerated hole (h+) in the pure photocatalytic process, while in the photosensitized process, the superoxide radical (•O2-) played a more important role. In conclusion, the immobilization process of the TiO2 semiconductor on PET polymer was efficient and the proposed material proved to be active for the degradation of recalcitrant organic pollutants.