A sustainable replacement for TiO2 in photocatalyst construction materials: Hydroxyapatite-based photocatalytic additives, made from the valorisation of food wastes of marine origin. (20th August 2018)

• Record Type: Journal Article
• Authors: Saeli, Manfredi; Piccirillo, Clara; Tobaldi, David M.; Binions, Russell; Castro, Paula M.L.; Pullar, Robert C.
• Is Part Of: Journal of cleaner production. Volume 193(2018)
• Page Start: 115
• Page End: 127
• Publication Date: 2018-08-20
• Subjects: Sustainable material -- Photocatalysis -- Hydroxyapatite -- Waste valorisation -- Construction material -- NHL mortar; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2018.05.030
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: 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 façades. 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 HAp-based 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 x pollutants under solar light. With intermixing, NO x abatement of 6.3–8.3% was observed. However, for coated mortars, superior NO x 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 façades, and environmentally sustainable materials for the preservation of cultural heritage. Graphical abstract: Image 1 Highlights: Sustainable photocatalyst mortar made with wastes using 100 times less TiO2 . First ever use of HAp or fishery/marine waste as additive in construction materials. This wastes-derived photocatalyst additive has a very low TiO2 level of only 1 wt%. Only 1–5 wt% added to mortar, so it contains only 0.01–0.05 wt% TiO2 (100–500 ppm). Excellent photocatalyst, degrading 23.8% NOx after 45 min under solar light.