Lorenzo Graziani

Superfici autopulenti e biocide nel restauro archeologico di pietre e laterizi

Archaeological artifacts are inevitably subject to deterioration caused by natural air pollution, contaminants by human actions, and biodeterioration from microorganisms. Their preservation is considered a more and more strategic factor in many countries because of their economic, social and cultural implications. Modern techniques of interventions often require re-application after some years, and they cannot be used in all restorations. Recently, the use of nanotechnologies was transferred to the restoration sector bringing many innovations. Titanium dioxide (TiO2) is the main nanostructured material used to prevent the comparison of weathering traces, to obtain self-cleaning materials and to slow down biofouling as well. In this paper, its potential use was tested on common archaeological materials like sandstone, limestone and bricks. The self-cleaning ability of this innovative material, as well as, its biofouling prevention were evaluated in laboratory simulated tests. Results show the high potentiality of this nanomaterial in making the tested archaeological surfaces self-cleaning and biocide.

Photocatalytic TiO2 Nano-Coating for Biofouling Prevention of Clay Façades

Energy saving in building construction is an actual problem and it is central to the debate. In order to ensure low energy consumption of a building, the global building thermal resistance and the airtightness were enhanced until “overinsulated” buildings and air permeability of the entire building envelope (opaque surfaces and windows) was reduced. In this way, moisture loads and surface condensations are favoured and ideal conditions for the proliferation of microorganisms arise. Innovative techniques for biofouling prevention include the application of nano-coatings able to destruct bond between cells of microorganisms and substrata. The most used nano-material is TiO2 because of its non-toxicity, photo-chemical stability and low cost. In this chapter, biofouling on brick substrata was presented, and the inhibitory effect of TiO2 was studied as an alternative method to traditional maintenance intervention. Biofouling was measured through time by digital image analysis and colorimetric measurements. Results show TiO2 was able to inhibit algal adhesion, and TiO2 efficiency is strictly related to physical properties of substrata like porosity and roughness.