Processi innovativi e sostenibili per la sintesi di nanoparticelle di idrossidi/ossidi di metalli. Sviluppi applicativi.

In the last decade, nanotechnologies have greatly developed in many research fields, such as engineering, biomedical, electronic and many others. They can offer several possibilities to design tools, to create new techniques or to improve the already existing ones, as well as to discover innovative applications. In fact, because of their small size, the characteristics and behaviours of nanomaterials can be very different compared to bulk materials having the same composition and can exhibit peculiar and new properties. Nanomaterials are typically obtained through two main ways: one refers to the so-called "top-down" approach, the other is called "bottom-up". However, several of these synthesis methods are characterized by multistep or complex procedures, working at high temperature and non-ambient pressure, and requiring organic synthesis media or sophisticated apparatus. Such features lead to an unavoidable low production yield and to an increase of times and costs to obtain pure products. For these reasons there is a lack of an economic method able to realize productions on large scale, which is of paramount importance for industrial applications, assuring a good control of the particles size and, at the same time, a desired not detrimental impact on the environment. In order to design and to engineer the nanoparticles as well as to tailor their characteristics to the final application, this thesis is aimed to define new scalable methods to produce a wide range of metal oxide/hydroxide nanoparticles with high production yields and low costs. These methods are characterized also by a special attention towards the environmental impact, limiting the production of wastes and the energetic costs of the process itself. The innovative synthesis techniques reported in this thesis and developed at the Laboratory of Technology of Materials and Applied Chemistry of the DIIIE Department of University of L’Aquila, are also object of a European patent (EP2880101) and of two Italian patents. By starting from the innovative procedure routes, both the synthesis, the characterization (by means of several consolidated laboratory techniques and of cutting edge techniques), and the application of the different kinds of nanoparticles were performed, from alkaline earth metal hydroxides/oxides to several type of iron oxides. Concerning the applications, different kinds of applicative interests were considered. Specifically, in Cultural Heritage, calcium hydroxide nanoparticles and calcium/iron oxide nanoparticles were successfully applied in the conservation of natural stones from architectonic monuments (biocalcarenites of Agrigento), and, thanks to the development of a prototype for large-scale production, in this thesis an extensive nanolime consolidation was realized, for the first time, on the facade of a historic building in L’Aquila. In addition, magnesium hydroxide nanoparticles were applied in the deacidification of ancient wood samples of a historic vessel. Moreover, in biomedical sector, magnesium oxide nanoparticles were preliminary investigated as anticancer agents on melanoma cells, while superparamagnetic iron oxide nanoparticles (SPIONs) were tested as contrast agents for magnetic resonance imaging (MRI). Finally, this PhD work involved several relationships with different National and international research groups, including the Departments of Physics and Industrial Engineering of the University of L'Aquila, the Department of Life Health and Environmental Sciences (MESVA) of the University of L’Aquila and the CNR-IOM-OGG group in the European Photon and Neutron Science Campus (EPN) of Grenoble.