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Tiocem
TioCem is a specialized cement with photocatalytic features, used on the surface of buildings to reduce air pollution caused by exposure of the cement to ultraviolet light (UV). Technology Photocatalysis is initiated by titanium dioxide (TiO2), which is added during the cement's production. Typical properties (i.e. strength) of cement applications (such as concrete) will be added to clean the air around the photocatalytic surface. Nitrogen dioxide (NO2) will be particularly abated when daylight activates the photocatalytic surfaces. The chemical process may be summarized as follows: *Titanium dioxide (TiO2) absorbs energy (UV radiation) and excites electrons (e-) TiO2 + hν -> TiO2 + h+ + e- *Oxygen existing in the air (O2) reacts with electrons (e-), generating super-oxide ions (O2-) *Super-oxide ions (O2-) react with hydrogen ions (H+), generating the reactive hydroxyl radicals (OH•) H2O + h+ -> H+ + OH- *Nitrogen dioxide (NO2) reacts with the pollutant remover (OH•) and gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource. Cements used in construction are usually inorganic, often lime- or calcium silicate-based, and are either hydraulic or less commonly non-hydraulic, depending on the ability of the cement to set in the presence of water (see hydraulic and non-hydraulic lime plaster). Hydraulic cements (e.g., Portland cement) set and become adhesive through a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble. This allows setting in wet conditions or u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. The photons of ultraviolet have greater energy than those of visible light, from about 3.1 to 12 electron volts, around the minimum energy required to ionize atoms. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack sufficient energy, it can induce chemical reactions and cause many substances to glow or fluoresce. Many practical applications, including chemical and biological effects, are derived from the way that UV radiation can interact with organic molecules. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium Dioxide
Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound derived from titanium with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or Colour Index International, CI 77891. It is a white solid that is insoluble in water, although mineral forms can appear black. As a pigment, it has a wide range of applications, including paint, sunscreen, and food coloring. When used as a food coloring, it has E number E171. World production in 2014 exceeded 9 million tonnes. It has been estimated that titanium dioxide is used in two-thirds of all pigments, and pigments based on the oxide have been valued at a price of $13.2 billion. Structure In all three of its main dioxides, titanium exhibits Octahedral molecular geometry, octahedral geometry, being bonded to six oxide anions. The oxides in turn are bonded to three Ti centers. The overall crystal structures of rutile and anatase are tetragonal in symmetry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen Dioxide
Nitrogen dioxide is a chemical compound with the formula . One of several nitrogen oxides, nitrogen dioxide is a reddish-brown gas. It is a paramagnetic, bent molecule with C2v point group symmetry. Industrially, is an intermediate in the synthesis of nitric acid, millions of tons of which are produced each year, primarily for the production of fertilizers. Nitrogen dioxide is poisonous and can be fatal if inhaled in large quantities. Cooking with a gas stove produces nitrogen dioxide which causes poorer indoor air quality. Combustion of gas can lead to increased concentrations of nitrogen dioxide throughout the home environment which is linked to respiratory issues and diseases. The LC50 ( median lethal dose) for humans has been estimated to be 174 ppm for a 1-hour exposure. It is also included in the NOx family of atmospheric pollutants. Properties Nitrogen dioxide is a reddish-brown gas with a pungent, acrid odor above and becomes a yellowish-brown liquid below . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up quark, up and down quark, down quarks. Electrons are extremely lightweight particles that orbit the positively charged atomic nucleus, nucleus of atoms. Their negative charge is balanced by the positive charge of protons in the nucleus, giving atoms their overall electric charge#Charge neutrality, neutral charge. Ordinary matter is composed of atoms, each consisting of a positively charged nucleus surrounded by a number of orbiting electrons equal to the number of protons. The configuration and energy levels of these orbiting electrons determine the chemical properties of an atom. Electrons are bound to the nucleus to different degrees. The outermost or valence electron, valence electrons are the least tightly bound and are responsible for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxyl
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both the negatively charged anion , called hydroxide, and the neutral radical , known as the hydroxyl radical, consist of an unbonded hydroxy group. According to IUPAC definitions, the term ''hydroxyl'' refers to the hydroxyl radical () only, while the functional group is called a ''hydroxy group''. Properties Water, alcohols, carboxylic acids, and many other hydroxy-containing compounds can be readily deprotonated due to a large difference between the electronegativity of oxygen (3.5) and that of hydrogen (2.1). Hydroxy-containing compounds engage in intermolecular hydrogen bonding increasing the electrostatic attraction between molecules and thus to higher boiling and melting points than found for compounds that lack thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical (chemistry)
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photocatalysis
In chemistry, photocatalysis is the acceleration of a photoreaction in the presence of a photocatalyst, the excited state of which "repeatedly interacts with the reaction partners forming reaction intermediates and regenerates itself after each cycle of such interactions." In many cases, the catalyst is a solid that upon irradiation with UV- or visible light generates electron–hole pairs that generate free radicals. Photocatalysts belong to three main groups; heterogeneous, homogeneous, and plasmonic antenna-reactor catalysts. The use of each catalysts depends on the preferred application and required catalysis reaction. History Early mentions (1911–1938) The earliest mention came in 1911, when German chemist Dr. Alexander Eibner integrated the concept in his research of the illumination of zinc oxide (ZnO) on the bleaching of the dark blue pigment, Prussian blue. Around this time, Bruner and Kozak published an article discussing the deterioration of oxalic acid in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladding (construction)
Cladding is the application of one material over another to provide a skin or layer. In construction, cladding is used to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings. Cladding can be made of any of a wide range of materials including wood, metal, brick, vinyl, and composite materials that can include aluminium, wood, blends of cement and recycled polystyrene, wheat/rice straw fibres. Rainscreen cladding is a form of weather cladding designed to protect against the elements, but also offers thermal insulation. The cladding does not itself need to be waterproof, merely a control element: it may serve only to direct water or wind safely away in order to control run-off and prevent its infiltration into the building structure. Cladding may also be a control element for noise, either entering or escaping. Cladding can become a fire risk by design or material. Description Cladding in construction is material applied o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whitetopping
Whitetopping is the covering of an existing asphalt pavement with a layer of Portland cement concrete. Whitetopping is divided into types depending on the thickness of the concrete layer and whether the layer is bonded to the asphalt substrate. Unbonded whitetopping, also called conventional whitetopping, uses concrete thicknesses of 20cm (8") or more that is not bonded to the asphalt. Bonded whitetopping uses thicknesses of 5 to 15cm (2-6") bonded to the asphalt pavement and is divided into two types, thin and ultrathin. The bond is made by texturing the asphalt. Thin whitetopping uses a bonded layer of concrete that is 10 - 15cm (4-6") thick while an ultrathin layer is 5 to 10 cm (2-4") thick. Ultrathin whitetopping is suitable for light duty uses, such as roads with low traffic volume, parking lots and small airports. Fiber reinforced concrete is used in some thin whitetopping overlays and almost all ultrathin whitetopping overlays. Whitetopping is suitable for asphalt pavement wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bergamo
Bergamo ( , ; ) is a city in the Alps, alpine Lombardy region of northern Italy, approximately northeast of Milan, and about from the alpine lakes Lake Como, Como and Lake Iseo, Iseo and 70 km (43 mi) from Lake Garda, Garda and Lake Maggiore, Maggiore. The Bergamo Alps () begin immediately north of the city. With a population of 120,580 as of 2025, Bergamo is the fourth-largest city in Lombardy. Bergamo is the seat of the province of Bergamo, which counts more than 1,115,037 residents as of 2025. The metropolitan area of Bergamo extends beyond the administrative city limits, spanning over a densely urbanized area with slightly fewer than 500,000 inhabitants. The Bergamo metropolitan area is itself part of the broader Milan metropolitan area, home to more than 8 million people. The city of Bergamo is composed of an old walled core, known as ('Upper Town'), nestled within a Parco dei Colli di Bergamo, system of hills, and the modern expansion in the plains below. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
