4. Conclusions

This work reports design, synthesis, and characterization of photocatalytic TiO2-coated tiles fabricated by the conventional jet spraying technique and the new technique of digital inkjet printing. The latter represents a significant improvement over the former, in that (1) it provides a more precise deposition as it utilizes piezoelectric heads to direct the suspension within an electrostatic field, (2) the microsized TiO2 powder strikes a medium that balances the small size advantageous for photocatalytic performance and the ability to resist solubility in the glass bonding to the tile against the large size that inhibits respirability, and (3) the topography of the digital inkjet-printed coating is less amenable to cell attachment and proliferation than those of the jet-sprayed coating.

The performance data show that the digital inkjet-printed coating was significantly more effective than the jet-sprayed coating in ethanol photodegradation. While the same trend was observed for toluene photodegradation, the difference was not as significant owing to direct photolysis of this aromatic compound. Both coatings were highly effective in destroying E. coli but the antibacterial activity with photocatalysis (ΔR) of the digital inkjet-printed coating was significantly superior to that of the jet-sprayed coating. Similarly, the LCA analysis of the impact assessments reveals the multifarious advantages of the digital inkjet-printed tile.
