The influence of clay brick substratum on the inhibitory efficiency of T_iO_2 nanocoating against biofouling

摘要

The goal of this study was to explain the influence of the total porosity and the surface roughness on the susceptibility of clay bricks to biodegradation by phototrophic microorganisms. In addition, this correlation was studied on both specimens treated with TiO_2 nanocoating and untreated control specimens. The effect of UV intensity on the photocatalytic power of T_iO_2 was also investigated. An accelerated fouling test was performed by sprinkling a suspension of Chlorella mirabilis and Chroococcidiopsis fissurarum on sample surfaces. These two test strains were chosen because their representativeness on building clay brick facades subjected to biofouling. The gradual superficial accumulation of algal biomass on treated and control specimens was evaluated by means of image analysis and colour measurement. Two specimens' parameters, namely porosity and roughness, were examined. Results showed that both the specimen microstructure and roughness of the surface play a key role in the colonization of clay bricks because they were able to provide more nutrient to the algal cells anchored to the surface. The T_iO_2 nanocoating was able to inhibit the biofouling of clay bricks irradiated with UV-A light, except in the case of high porous rough specimens.