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Sodium Sulfite
Sodium sulfite (sodium sulphite) is the inorganic compound with the chemical formula Na2SO3. A white, water-soluble solid, it is used commercially as an antioxidant and preservative. It is also suitable for the softening of lignin in the pulping and refining processes of wood and Lignocellulosic biomass, lignocellulosic materials. A heptahydrate is also known but it is less useful because of its greater susceptibility toward oxidation by air. Preparation image:Sodium-sulfite-xtal-3x3x3-c-3D-bs-17.png, Structure of anhydrous sodium sulfite, left, thumb Sodium sulfite can be prepared by treating a solution of sodium hydroxide with sulfur dioxide. When conducted in warm water, Na2SO3 initially precipitates as a white solid. With more SO2, the solid dissolves to give the Na2S2O5, disulfite, which crystallizes upon cooling. : Sodium sulfite is made industrially by treating sulfur dioxide with a solution of sodium carbonate. The overall reaction is: : Uses Sodium sulfite is primaril ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycerol
Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pharmaceutical formulations. Because of its three hydroxyl groups, glycerol is miscible with water and is Hygroscopy, hygroscopic in nature. Modern use of the word glycerine (alternatively spelled glycerin) refers to commercial preparations of less than 100% purity, typically 95% glycerol. Structure Although chirality, achiral, glycerol is prochirality, prochiral with respect to reactions of one of the two primary alcohols. Thus, in substituted derivatives, the Glycerophospholipid#Nomenclature and stereochemistry, stereospecific numbering labels the molecule with a ''sn''- prefix before the stem name of the molecule. Production Natural sources Glycerol is generally obtained from plant and animal sources where it occurs in triglycerides, est ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulp And Paper Industry
The pulp and paper industry comprises companies that use wood, specifically pulpwood, as raw material and produce pulp, paper, paperboard, and other cellulose-based products. Manufacturing process In the manufacturing process, pulp is introduced into a paper machine where it is shaped into a paper web and water is extracted through pressing and drying stages. Pressing involves removing water from the sheet by applying force. This process employs a specialized type of felt, distinct from traditional felt, to absorb the water. In contrast, hand-made paper uses a blotter sheet for this purpose. Drying involves eliminating water from the paper sheets through air or heat. Historically, this was achieved by hanging the sheets to dry, similar to laundry. In modern papermaking, various heated drying mechanisms are employed, with the steam-heated can dryer being the most prevalent on paper machines. History Papermaking as a craft is ancient, and for centuries it used various fibers, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Compounds
Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. As a result, sodium usually forms ionic compounds involving the Na+ cation. Sodium is a reactive alkali metal and is much more stable in ionic compounds. It can also form intermetallic compounds and organosodium compounds. Sodium compounds are often soluble in water. Metallic sodium Metallic sodium is generally less reactive than potassium and more reactive than lithium. Sodium metal is highly reducing, with the standard reduction potential for the Na+/Na couple being −2.71 volts, though potassium and lithium have even more negative potentials. The thermal, fluidic, chemical, and nuclear properties of molten sodium metal have caused it to be one of the main coolants of choice for the fast breeder reactor. Such nuclear reactors are seen as a crucial step for the production of clean energy. Salts and oxides Sodium compounds are of immense commercial importance, being particularly centr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Chemicals
Photography is the art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication. A person who operates a camera to capture or take photographs is called a photographer, while the captured image, also known as a photograph, is the result produced by the camera. Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring the angles and intensities of the X-ray diffraction, a crystallography, crystallographer can produce a three-dimensional picture of the density of electrons within the crystal and the positions of the atoms, as well as their chemical bonds, crystallographic disorder, and other information. X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences between various materials, especially minerals and alloys. The method has also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA. X-ray crystall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Efflorescence
In chemistry, efflorescence (Derived from the Latin verb 'efflorescere' roughly meaning 'to flower') is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water or occasionally, in another solvent. The water, with the salt now held in solution, migrates to the surface, then evaporates, leaving a coating of the salt. In what has been described as "primary efflorescence", the water is the invader and the salt was already present internally, and a reverse process, where the salt is originally present externally and is then carried inside in solution, is referred to as "secondary efflorescence". Efflorescences can occur in natural and built environments. On porous construction materials it may present a cosmetic outer problem only (primary efflorescence causing staining), but can sometimes indicate internal structural weakness (migration/degradation of component materials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flue Gas Desulfurization
Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide () from exhaust flue gases of fossil-fuel power plants, and from the emissions of other sulfur oxide emitting processes such as waste incineration, petroleum refineries, cement and lime kilns. Methods Since stringent environmental regulations limiting emissions have been enacted in many countries, is being removed from flue gases by a variety of methods. Common methods used: * Wet scrubbing using a slurry of alkaline sorbent, usually limestone or lime, or seawater to scrub gases; * Spray-dry scrubbing using similar sorbent slurries; * Wet sulfuric acid process recovering sulfur in the form of commercial quality sulfuric acid; * SNOX Flue gas desulfurization removes sulfur dioxide, nitrogen oxides and particulates from flue gases; *Dry sorbent injection systems that introduce powdered hydrated lime (or other sorbent material) into exhaust ducts to eliminate and from process emissions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wellman–Lord Process
The Wellman–Lord process is a regenerable process to remove sulfur dioxide from flue gas (flue-gas desulfurization) without creating a throwaway sludge product. In this process, sulfur dioxide from flue gas is absorbed in a sodium sulfite solution in water forming sodium bisulfite; other components of flue gas are not absorbed. After lowering the temperature the bisulfite is converted to the sodium pyrosulfite which precipitates. Upon heating, the two previously described chemical reactions are reversed, and sodium pyrosulfite is converted to a concentrated stream of sulfur dioxide and sodium sulfite. The sulfur dioxide can be used for further reactions (e.g. the production of sulfuric acid), and the sulfite is reintroduced into the process. :Na2SO3 + SO2 + H2O → 2NaHSO3 :2NaHSO3 → Na2S2O5↓ + H2O :Na2S2O5 + H2O → 2NaHSO3 :2NaHSO3 → Na2SO3 + SO2 + H2O In its initial version ( Crane Station, Maryland, 1968) the process was based on potassium sulfite, but the econ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfonation
In organic chemistry, aromatic sulfonation is a reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid () group. Together with nitration and chlorination, aromatic sulfonation is a widely used electrophilic aromatic substitutions. Aryl sulfonic acids are used as detergents, dye, and drugs. : Stoichiometry and mechanism Typical conditions involve heating the aromatic compound with sulfuric acid: : Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution. To drive the equilibrium, dehydrating agents such as thionyl chloride can be added: : Historically, mercurous sulfate has been used to catalyze the reaction. Chlorosulfuric acid is also an effective agent: : In contrast to aromatic nitration and most other electrophilic aromatic substitutions this reaction is reversible. Sulfonation takes place in concentrated acidic conditions and desulfonation is the mode of action in a dilute hot aqueou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dried Fruit
Dried fruit is fruit from which the majority of the original water content has been removed prior to cooking or being eaten on its own. Drying may occur either naturally, by sun, through the use of industrial dehydrators, or by freeze drying. Dried fruit has a long tradition of use dating to the fourth millennium BC in Mesopotamia, and is valued for its sweet taste, nutritional content, and long shelf life. In the 21st century, dried fruit consumption is widespread worldwide. Nearly half of dried fruits sold are raisins, followed by dates, prunes, figs, apricots, peaches, apples, and pears. These are referred to as "conventional" or "traditional" dried fruits: fruits that have been dried in the sun or in commercial dryers. Many fruits, such as cranberries, blueberries, cherries, strawberries, and mango are infused with a sweetener (e.g., sucrose syrup) prior to drying. Some products sold as dried fruit, like papaya, kiwifruit and pineapple, are most often candied fruit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preservative
A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying.Erich Lück and Gert-Wolfhard von Rymon Lipinski "Foods, 3. Food Additives" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2002, Wiley-VCH, Weinheim. Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Thiosulfate
Sodium thiosulfate (sodium thiosulphate) is an inorganic compound with the formula . Typically it is available as the white or colorless pentahydrate (x = 5), which is a white solid that dissolves well in water. The compound is a reducing agent and a ligand, and these properties underpin its applications. Uses Sodium thiosulfate is used predominantly in dyeing. It converts some dyes to their soluble colorless "leuco" forms. It is also used to bleach "wool, cotton, silk, ...soaps, glues, clay, sand, bauxite, and... edible oils, edible fats, and gelatin." Medical uses Sodium thiosulfate is used in the treatment of cyanide poisoning. It is on the World Health Organization's List of Essential Medicines. Other uses include topical treatment of ringworm and tinea versicolor, and treating some side effects of hemodialysis and chemotherapy. In September 2022, the U.S. Food and Drug Administration (FDA) approved sodium thiosulfate under the trade name Pedmark to lessen the risk of oto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
