Evaluation of the effectiveness of CuONPs/SiO2-based treatments for building stones against the growth of phototrophic microorganisms

Colonization by phototrophic microorganisms causes a range of problems for building fa ades, The combination of biological physical and chemical agents accelerates the decay of materials. For this reason, in recent years there has been a growing interest in the application of multifunctional treatments that combine consolidant and biocidal action. In this study, the effectiveness of a nano-structured CuONPs/SiO2-based multifunctional treatment for the prevention of algal growth was evaluated on two different stones by using two complementary techniques, namely Chlorophyll a fluorescence and spectrophotometric determination. The results showed a delay in the algal colonization for two reasons: (1) The SiO2 matrix modified the roughness and surface tension, thus delaying the initial setting, and (2) the CuONPs decreased the viability of the phototrophic organisms at longer exposure times. (C) 2018 Elsevier Ltd. All rights reserved.