Studies on SnCl2-doped TiO2 photocatalyst for pyrocatechol photodegradation

cited By 1International audienceSnCl2-doped TiO2 photocatalyst for pyrocatechol photodegradation aimed to examine the effect of Sn/Ti ratio and H2O2+UVC irradiation. The preparation was carried out by the impregnation and the characterization consisted of WAXD, SEM, and laser particle size. Using 1 mM pyrocatechol in the CSTR with various TiO2 photocatalysts, the remaining pyrocatechol was determined by UV-vis spectrophotometry to calculate % photodegradation. From WAXD results, it was found that SnO2 incorporation to the TiO2 bulk phase but the morphologies did not change. And the particle size changed due to the attraction force of the surface charging. Without H2O2 addition, it showed 15.7% photodegradation by TiSn10UVC compared to 11.37% of TiDark. Thus, UVC was the important factor for photodegradation. With H2O2+UVC irradiation, the maximum photodegradation reached 34.6% by TiSn10HOUVC, but those of HOUVC and TiHOUVC showed 25.0% and 26.5%, respectively. The Sn-doping affected the formation of more hydroxyl free radical from H2O2+UVC irradiation and charge separation. But higher Sn/Ti ration, it gave segregate SnO2 which increased recombination center with the adverse effect on the lower photodegradation. The conclusion revealed that SnCl2-doping with the ratio of Sn/Ti =10 onto TiO2 photocatalyst showed the highest photoactivity with H2O2+UVC irradiation. Moreover, the chemical kinetics is also discussed

Dynamic surface and interfacial tension of afff and fluorine-free class B foam solutions

This paper investigates the dynamic surface tension of aqueous film forming (AFFF) and fluorine-free (FF) foam solutions by pendant drop tensiometry. Additional experiments are conducted to measure the interfacial tension between the foam solutions and two hydrocarbon liquids, n-heptane and diesel oil. The pendant drop technique yields both surface and interfacial tension at time scales ranging from seconds to hours, being limited at the lower end by the time necessary to form a droplet, and at the upper end by the evaporation of the droplet’s material. The results indicate that the surface tension of AFFF formulations, diluted at the design concentration, rapidly reaches its equilibrium value. However, the approach to equilibrium is slowed down by additives, such as xanthan gum, present in the alcohol tolerant concentrates (ATC-AFFF). FF solutions show a slower approach to static values than AFFF formulations. At the design dilution, and at room temperature, these static values are in the order of 27 mN m-1, as compared to 16 mN m-1 for AFFF solutions. The measurements of the interfacial tension indicate rapid attainment of equilibrium for both AFFF and FF formulations, with the static values of around 2 and 0.9-2.5 mN m-1, for AFFF and FF, respectively. With the surface tension of n-heptane and diesel oil of 20.1 and 28.3 mN m-1, the spreading coefficient of FF formulations for the present systems varies between –9.4 and 0.6 mN m-1. These results indicate that film formation does not play a role during fire suppression by FF foams