Abstract
Nanotechnology is a field of science that is nowadays developing in a dynamic way. It seems to offer almost endless opportunities of contribution to many areas of economy and human activity, in general. Thanks to nanotechnology, the so-called nanomaterials can be designed. They present structurally altered materials, with their physical, chemical and biological properties entirely differing from properties of the same materials manufactured in microtechnology. Nanotechnology creates a unique opportunity to modify the matter at the level of atoms and particles. Therefore, it has become possible to obtain items displaying new, useful properties, i.e. self-disinfecting and self-cleaning surfaces. Those surfaces are usually covered by a thin layer of a photocatalyst. The role of the photocatalyst is most of the time performed by the nanosized titanium dioxide (nano-TiO2). Excitation of nano-TiO2 by ultraviolet radiation initiates advanced oxidation processes and reactions leading to the creation of oxygen vacancies that bind water particles. As a result, photocatalytic surfaces are given new properties. Those properties can then be applied in a variety of disciplines, such as medicine, food hygiene, environmental protection or building industry. Practically, the applications include inactivation of microorganisms, degradation of toxins, removing pollutants from buildings and manufacturing of fog-free windows or mirrors.
Highlights
The past decade redounded the discovery that many materials used in a number of industries - e.g. titanium white (TiO2) and zinc white (ZnO) applied in the manufacturing of paints and varnishes, refractory magnesia (MgO) added to cement, or silica (SiO2) applied in the fabrication of glass products - after they have been powdered to nanoparticles (NPs) (1 < φ ≤ 100 nm), significantly alter their properties, i.e. they exhibit increased hardness, tensile strength, plasticity [1], higher resistance to chemical agents [2], greater hydrophilicity [3] orcatalytic properties [4]
Nanotechnology allows modifying the properties of various materials through alteration of their structure at the level of atoms and molecules
Products can be designed that are incomparably better than microtechnology products
Summary
The past decade redounded the discovery that many materials used in a number of industries - e.g. titanium white (TiO2) and zinc white (ZnO) applied in the manufacturing of paints and varnishes, refractory magnesia (MgO) added to cement, or silica (SiO2) applied in the fabrication of glass products - after they have been powdered to nanoparticles (NPs) (1 < φ ≤ 100 nm), significantly alter their properties, i.e. they exhibit increased hardness, tensile strength, plasticity [1], higher resistance to chemical agents [2], greater hydrophilicity [3] or (photo)catalytic properties [4]. The surface of nanoTiO2 particles becomes enfolded by a thin layer with a high carbon share that nearly completely stops their photocatalytic properties [5], without simultaneously altering their other physicochemical properties It means that nano-TiO2 modified in this way is safe for the human skin. The application of nano-TiO2 onto surfaces by means of magnetron sputtering deposition [62], chemical vapour deposition [63] or sol-gel deposition [64] results in an inseparably base-fixed, resistant to mechanical factors, thin layer of photocatalyst The application of those technologies allows to significantly reduce the health damage risk, resulting from the transmission of nano-TiO2 from photocatalytic coatings to the environment and from the contact of free NPs, i.e. with human or animal bronchial epithelial cells. TiO2 is applied, after powdering to NPs, in AOPs and UV radiation-based methods for pathogen inactivation and organic pollutant decomposition [82]
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