abstract
This work reports the development of extruded porcelain stoneware tiles that show antimicrobial (to act as a barrier to the bacteria's growth during a long period of time), and anti-stain (easy to clean) actions, and possess high chemical resistance. The antimicrobial action was proven through the reduction of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. Staining and chemical resistance were tested according to ISO 10545-14 and 10545-13 standards, respectively. The tiles promote a population reduction of over 77% and 81% for the S. aureus and the E. colt bacteria, respectively. The optimized product was obtained by adding 2.5 wt% of a black ceramic pigment to the industrially-prepared paste, followed by the application of a small quantity of glaze (by jet spraying). Chemical (solution of 98 wt% NaNO3 and 2 wt% AgNO3) and thermal (2 h at 430 degrees C) treatments were finally applied to get the active surface. In terms of anti-staining characteristics the tiles belong to class 5, while their chemical resistance is excellent (UA, ULA and UHA) against almost all aggressive agents, except for chloridric acid, 18% (v/v), for which a small surface attack (UHB) was observed. Furthermore, the treatments used (chemical and thermal) do not change the surface aspect of the product, and thus fulfil the industrial/commercial requirements. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
keywords
ESCHERICHIA-COLI; ANTIBACTERIAL ACTIVITY; SILVER NANOPARTICLES; STAPHYLOCOCCUS-AUREUS; TOXICITY; MATRIX; METALS; IONS; GOLD
subject category
Materials Science
authors
Seabra, MP; Grave, L; Oliveira, C; Alves, A; Correia, A; Labrincha, JA
our authors
João António Labrincha Baptista
Full professor
Maria Paula Seabra
Assistant Professoracknowledgements
Authors acknowledge PEst-C/CTM/LA0011/2013 programme and R.C. Pullar for comments and corrections to the English. M.P. Seabra wishes to thank the FCT Ciencia2008 programme for supporting this work. The support of Aleluia Ceramicas S.A. in performing the industrial trials should also be emphasized.; C. Oliveira was supported through grant SFRH/BPD/65820/2009 to CO, from Fundo Social Europeu and by Ministerio da Ciencia, Tecnologia e Ensino Superior, Portugal. A. Alves was supported by the programme Ciencia2008, co-funded by the Human Potential Operational Programme (National Strategic Reference Framework 2007-2013) and European Social Fund (EU).