engleski

Predictive models for environmental pollutants degradation by solar photocatalysis in flat-plate reactors; semi-pilot to real scale applications

The most challenging aspect of water treatment is to remove the recalcitrant trace organic pollutants from wastewaters. In this study, we report the application of photocatalytic oxidation process for the degradation of residual pollutants often found in surface water. The presence of these ecotoxic substances in the aquatic environment is given full consideration in the frame of on-going EU regulations as priority and emerging substances that need to be reduced (amendments to the Water Framework Directive). On the other hand, TiO 2 photocatalysis is listed as emerging best available technique (BAT) in the reference document for common wastewater and waste gas treatment/management systems in the chemical sector. Widespread research has been made into the photocatalytic properties of TiO 2 because of its ability to break down and destroy many types of pollutants. However, outdoor applications of this technology are still developing, primarily due to small quantum efficiencies and the lack of simple methods for the design, optimization and scale-up of photocatalytic reactor systems. Semi-pilot scale flat-plate cascade reactor (FPCR) was fabricated to study the solar photocatalytic degradation of common organic pollutants: 1H-benzotriazole, carbamazepine, imidacloprid, 17-estradiol and ibuprofen over TiO 2 and TiO 2 /CNT thin-film supported on glass fibers. The FPCR represents the more realistic outdoor system that is simple yet can be easily scaled-up and installed at the outlet of municipal water treatment plants or in the critical part of a recipient. The modular panel with the full-spectra solar lamps having appropriate UVB and UVA irradiation levels was used as a simulation of sunlight. The experimental results consisted of comprehensive data of primary pollutants and their by-products analysis using LC/Q-TOF/MS technique. The predictive models were developed to estimate the pollutant degradation in flat-plate reactors independent on the reactor size and capacity. The comprehensive model was consisted of three sub- models: radiation emission, fluid-dynamics in a rectangular open channel in a cascade set-up and the reaction kinetics coupled with irradiation absorption and combined with the appropriate mass balance. The model was effectively applied for different irradiation conditions typical for Northern Croatia (~ 45 ° N) and the degradation extents for studied pollutants throughout the year were estimated. The “intrinsic” photocatalytic reaction constants for targeted pollutants, independent of irradiance levels, reactor geometry and hydrodynamics were presented. Furthermore, the location for real scale implementation of surface water treatment by solar photocatalysis over supported TiO 2 was chosen and the ongoing research will be presented accordingly.

solar photocatalysis, air purification, pollutant degradation, titanium dioxide

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