Nano-TiO2-based architectural mortar for NO removal and bacteria inactivation: Influence of coating and weathering conditions

Abstract In the present study, the photocatalytic activities of TiO2 dip-coated self-compacting glass mortars (SCGMs), in terms of air pollutant removal and bacteria inactivation, were investigated and compared. TiO2 dip-coated glass was used as the control to compare performance. Nitrogen oxide (NO) and Escherichia coli K12 were used as the target air pollutant and bacteria test strain respectively. In addition, the weathering resistance of TiO2-coated samples was evaluated. In the case of NO removal, it is clear that no significant difference between TiO2 dip-coated glass and SCGM was observed, and both exhibited high NO removal efficiency when condition 1 (C1, no weathering) was applied (for EtOH-mortar, up to 14.33 mg m−2 h−1). However, after a period of abrasive weathering, condition 3 (C3, abrasive process), the NO removal ability of the TiO2 dip-coated glass samples almost completely disappeared. In contrast, the NO removal ability of the dip-coated SCGM still remained high (for EtOH-mortar, 8.75 mg m−2 h−1). It appears that the porosity of the dip-coated SCGM surface contributed to favourable TiO2 particles retention after the abrasion action. As for the antibacterial activity, a total inactivation of E. coli was observed on the TiO2 dip-coated glass and SCGM samples within 60 min of UV irradiation. The E. coli inactivation of TiO2 dip-coated glass was nearly negligible after the abrasion process (C3), whereas, the concentration of E. coli remaining on the surface of TiO2 dip-coated SCGM only dropped from about 105 to 103 CFU/mL. The results suggest that the TiO2 retained in the porosity of the dip-coated SCGM can still make a contribution to the E. coli inactivation. Taking all the results into account, it can be concluded that photocatalytic bacteria inactivation is a more complex process and the results for photocatalytic activity of NO removal cannot always be extrapolated to photocatalytic antibacterial activity.

[1]  Ichiro Okura,et al.  Photocatalysis Science and Technology , 2002 .

[2]  Eiichi Kojima,et al.  Light-induced amphiphilic surfaces , 1997, Nature.

[3]  Xudong Yang,et al.  Photocatalytic oxidation for indoor air purification: a literature review , 2003 .

[4]  Chi Sun Poon,et al.  Photocatalytic construction and building materials: From fundamentals to applications , 2009 .

[5]  J. Freihaut,et al.  Photocatalytic Oxidation of Toluene on Nanoscale TiO2 Catalysts: Studies of Deactivation and Regeneration , 2000 .

[6]  G Götz Hüsken,et al.  Experimental study of photocatalytic concrete products for air purification , 2009 .

[7]  Anita Rachel,et al.  Comparison of photocatalytic efficiencies of TiO2 in suspended and immobilised form for the photocatalytic degradation of nitrobenzenesulfonic acids , 2002 .

[8]  Francois Olive,et al.  TiO2-containing cement pastes and mortars: Measurements of the photocatalytic efficiency using a rhodamine B-based colourimetric test , 2009 .

[9]  Chi Sun Poon,et al.  Properties of architectural mortar prepared with recycled glass with different particle sizes , 2011 .

[10]  M. A. Henderson.  A surface science perspective on TiO2 photocatalysis , 2011 .

[11]  F. Pacheco-Torgal,et al.  Nanotechnology: Advantages and drawbacks in the field of construction and building materials , 2011 .

[12]  Reinhard Niessner,et al.  Photocatalytic activity of semiconductor-modified cement. Influence of semiconductor type and cement ageing , 2003 .

[13]  Rafael van Grieken,et al.  Kinetics of the photocatalytic disinfection of Escherichia coli suspensions , 2008 .

[14]  R. T. Brown,et al.  TiO2 Photocatalysis for Indoor Air Applications: Effects of Humidity and Trace Contaminant Levels on the Oxidation Rates of Formaldehyde, Toluene, and 1,3-Butadiene. , 1995, Environmental science & technology.

[15]  Hjh Jos Brouwers,et al.  Experimental study of the NO and NO2 degradation by photocatalytically active concrete , 2011 .

[16]  J. Marugán,et al.  Analogies and differences between photocatalytic oxidation of chemicals and photocatalytic inactivation of microorganisms. , 2010, Water research.

[17]  Nele De Belie,et al.  Titanium dioxide coated cementitious materials for air purifying purposes: Preparation, characterization and toluene removal potential , 2010 .

[18]  Kayano Sunada,et al.  Studies on photokilling of bacteria on TiO2 thin film , 2003 .

[19]  Xiaobo Chen,et al.  Titanium dioxide nanomaterials: synthesis, properties, modifications, and applications. , 2007, Chemical reviews.

[20]  Alberto Strini,et al.  Measurement of benzene, toluene, ethylbenzene and o-xylene gas phase photodegradation by titanium dioxide dispersed in cementitious materials using a mixed flow reactor , 2005 .

[21]  Chi Sun Poon,et al.  Photocatalytic cement-based materials: Comparison of nitrogen oxides and toluene removal potentials , 2011 .

[22]  A. Fujishima,et al.  TiO2 photocatalysis and related surface phenomena , 2008 .

[23]  Akira Fujishima,et al.  Titanium dioxide photocatalysis , 2000 .

[24]  R. Leary,et al.  Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis , 2011 .

[25]  Chi Sun Poon,et al.  Feasibility of using recycled glass in architectural cement mortars , 2011 .

[26]  Jo Dewulf,et al.  Heterogeneous photocatalytic removal of toluene from air on building materials enriched with TiO2 , 2008 .

[27]  Florence Sanchez,et al.  Nanotechnology in concrete – A review , 2010 .

[28]  Jun Chen,et al.  Photocatalytic cementitious materials: influence of the microstructure of cement paste on photocatalytic pollution degradation. , 2009, Environmental science & technology.

[29]  Louay N. Mohammad,et al.  Evaluation of the durability of titanium dioxide photocatalyst coating for concrete pavement , 2010 .