TiO2-based self-compacting glass mortar: Comparison of photocatalytic nitrogen oxide removal and bacteria inactivation

This paper presents the results of a preliminary study on assessing the photocatalytic activities when nano-TiO2 is intermixed in self-compacting glass mortars (SCGM) in terms of the air pollutant removal and bacteria inactivation. Nitrogen oxide (NO) and Escherichia coli K12 were used as the target air pollutant and bacteria test strain respectively. In addition, the influence of nano-TiO2 dosage (0%, 2% and 5%) and recycled glass colour (light green and transparent) on the fluidity and compressive strength of nano-TiO2-based SCGM was also evaluated. The results showed that more superplasticizer dosage was required to help the dispersion of nano-TiO2 particles to achieve the same fluidity. Meanwhile, with the addition of nano-TiO2 either 2% or 5%, about a 12% compressive strength increment was observed in SCGM. In the case of NO removal, an increasing trend of NO removal was accompanied by an increase in TiO2 content. For a given dosage of TiO2, the SCGM prepared with transparent recycled glass showed a slightly higher NO removal rate than that prepared with light green recycled glass. As for the antibacterial activity, however, all of the TiO2 intermixed SCGMs showed little inactivation ability of E. coli. Taking into account the above obtained results, it can be concluded that compared with NO removal, 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.