A sustainable replacement for TiO2 in photocatalyst construction materials: Hydroxyapatite-based photocatalytic additives, made from the valorisation of food wastes of marine origin


The use of waste materials and by-products in building materials is of increasing importance to improve sustainability in construction, as is the incorporation of photocatalytic materials to both combat atmospheric pollution and protect the structures and fa ades. This work reports the innovative use of photocatalytic hydroxyapatite (HAp) based powders, derived from Atlantic codfish bone wastes, as an additive to natural hydraulic lime mortars. HAp is the main component of bone, and hence is non-toxic and biocompatible. This is the first time that such a calcium phosphate-based photocatalyst, or indeed any fish/marine derived wastes, have been added to building materials. A key factor is that this HApbased photocatalyst contains only 1 wt% TiO2, the material usually used as a photocatalyst in construction materials. As we only add 1-5 wt% of our total HAp-based material to the mortar, this means our photocatalytic mortars only contain 0.01-0.05 wt% titania (100-500 ppm), two orders of magnitude less than the quantities of 2-10 wt% TiO2 which are usually needed. Our photocatalyst is made from a sustainable waste stream by simple solution and thermal processing, and thus with a much smaller impact on the environment. Specimens were made by either traditional intermixing techniques, or by a post -curing coating procedure. All showed gas-phase photocatalytic activity for abatement of NO pollutants under solar light. With intermixing, NOx abatement of 6.3-8.3% was observed. However, for coated mortars, superior NOx conversion rates were achieved of 7.1% and 23.8%, with 1 and 5 wt% additions, respectively. These results show the potential of this naturally-derived photocatalyst for applications in the construction industry, leading to lower atmospheric pollution and the creation of more durable/lower maintenance building fa ades, and environmentally sustainable materials for the preservation of cultural heritage. (C) 2018 Elsevier Ltd. All rights reserved.




Science & Technology - Other Topics; Engineering; Environmental Sciences & Ecology


Saeli, M; Piccirillo, C; Tobaldi, DM; Binions, R; Castro, PML; Pullar, RC

nossos autores


The authors wish to thank the company Saint-Gobain Weber Portugal, S.A. (Zona Industrial de Taboeira, 3800-055 Aveiro, Portugal) for providing natural hydraulic lime (Weber Rev 158), with particular thanks to Eng. Luis Silva, Eng. Nuno Vieira and Eng. Pedro Sequeira. This work was also funded by PEst-OE/EQB/LA0016/2013 programmes, and developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. M. Saeli wishes to thank the University of Palermo for supporting this work (Post-doc fellowships funded by the Benefict 5x1000, Decreto N. 447/2013). C. Piccirillo and R.C. Pullar wish to thank the FCT for support via grants SFRH/BPD/86483/2012, and SFRH/BPD/97115/2013 and IF/00681/2015, respectively.

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