Recent architectural trends are pushing for the development of pigmented photocatalytic coatings for building applications. The presence of a pigment in the formulation can however be detrimental for the photocatalytic activity because of possible phenomena of photon absorption competition. In the present study, the effects of three selected mineral color dyes (yellow, red and blue, respectively) on the activity of photocatalytic plaster were assessed by measuring the nitric oxide (NO) degradation in air. All samples for photocatalytic measurements were prepared using an experimental photocatalytic cement plaster premix based on photocatalytic white cement (i.active, Italcementi) and industrial inorganic color dyes in different concentrations from 0.05% to 2% (as dye/dry matter w/w ratio). The photocatalytic activity of the samples was assessed by measuring the degradation of NO at 75 ppb in air using a dedicated experimental system. Optical absorbance of dyes was evaluated by measuring the reflectance spectra of dye dispersions in gypsum (calcium sulphate, reagent grade). The UV-Vis reflection spectra of gypsum-dispersed dyes demonstrate different UV absorption profile with respect to the visible optical absorbance. Particularly, a relatively high UV adsorption was measured for the yellow and red pigments, while the blue pigment demonstrated a remarkably lower absorption. The photocatalytic activity of yellow and red colored samples indicates a strong correlation between dye content and photocatalytic activity while the activity of blue samples (characterized by a low UV absorbance), appears to be slightly influenced by the presence of the dye. The reported evidences indicate a significant correlation between the UV pigment absorbance and the respective interference with the photocatalytic activity, with a significant inhibition effect demonstrated by the yellow and red pigments (UV absorbing) and a negligible effect for the blue pigment (low UV absorbing). These results suggest a major role of UV absorption competition in the determination of the final performance of colored photocatalytic plasters. The selection of an appropriate pigment (with minimized UV absorbance) therefore appears to be a key factor in order to optimize the performances of photocatalytic color plasters.
Photocatalytic activity of color pigmented plasters
Strini A;Marras P;
2017
Abstract
Recent architectural trends are pushing for the development of pigmented photocatalytic coatings for building applications. The presence of a pigment in the formulation can however be detrimental for the photocatalytic activity because of possible phenomena of photon absorption competition. In the present study, the effects of three selected mineral color dyes (yellow, red and blue, respectively) on the activity of photocatalytic plaster were assessed by measuring the nitric oxide (NO) degradation in air. All samples for photocatalytic measurements were prepared using an experimental photocatalytic cement plaster premix based on photocatalytic white cement (i.active, Italcementi) and industrial inorganic color dyes in different concentrations from 0.05% to 2% (as dye/dry matter w/w ratio). The photocatalytic activity of the samples was assessed by measuring the degradation of NO at 75 ppb in air using a dedicated experimental system. Optical absorbance of dyes was evaluated by measuring the reflectance spectra of dye dispersions in gypsum (calcium sulphate, reagent grade). The UV-Vis reflection spectra of gypsum-dispersed dyes demonstrate different UV absorption profile with respect to the visible optical absorbance. Particularly, a relatively high UV adsorption was measured for the yellow and red pigments, while the blue pigment demonstrated a remarkably lower absorption. The photocatalytic activity of yellow and red colored samples indicates a strong correlation between dye content and photocatalytic activity while the activity of blue samples (characterized by a low UV absorbance), appears to be slightly influenced by the presence of the dye. The reported evidences indicate a significant correlation between the UV pigment absorbance and the respective interference with the photocatalytic activity, with a significant inhibition effect demonstrated by the yellow and red pigments (UV absorbing) and a negligible effect for the blue pigment (low UV absorbing). These results suggest a major role of UV absorption competition in the determination of the final performance of colored photocatalytic plasters. The selection of an appropriate pigment (with minimized UV absorbance) therefore appears to be a key factor in order to optimize the performances of photocatalytic color plasters.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
