|
Suspensions
In chemistry, a suspension is a heterogeneous mixture of a fluid that contains solid particles sufficiently large for sedimentation. The particles may be visible to the naked eye, usually must be larger than one micrometer, and will eventually settle, although the mixture is only classified as a suspension when and while the particles have not settled out. Properties A suspension is a heterogeneous mixture in which the solid particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium. The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending agents. An example of a suspension would be sand in water. The suspended particles are visible under a microscope and will settle over time if left undisturbed. This distinguishes a suspension from a colloid, in which the colloid particles are smaller and do not settle. Colloids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colloid
A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word '' suspension'' is distinguished from colloids by larger particle size). A colloid has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension). The dispersed phase particles have a diameter of approximately 1 nanometre to 1 micrometre. Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color. Colloidal suspensions are the subject of interface and colloid science. This field of study began in 1845 by Franc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentation
Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration, or electromagnetism. Settling is the falling of suspended particles through the liquid, whereas sedimentation is the final result of the settling process. In geology, sedimentation is the deposition of sediments which results in the formation of sedimentary rock. The term is broadly applied to the entire range of processes that result in the formation of sedimentary rock, from initial erosion through sediment transport and settling to the lithification of the sediments. However, the strict geological definition of sedimentation is the mechanical deposition of sediment particles from an initial suspension in air or water. Sedimentation may pertain to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-shear Mixer
A high-shear mixer disperses, or transports, one phase or ingredient (liquid, solid, gas) into a main continuous phase (liquid), with which it would normally be immiscible. A rotor or impeller, together with a stationary component known as a stator, or an array of rotors and stators, is used either in a tank containing the solution to be mixed, or in a pipe through which the solution passes, to create shear. A high-shear mixer can be used to create emulsions, suspensions, lyosols (gas dispersed in liquid), and granular products. It is used in the adhesives, chemical, cosmetic, food, pharmaceutical, and plastics industries for emulsification, homogenization, particle size reduction, and dispersion. Principles of work Fluid undergoes shear when one area of fluid travels with a different velocity relative to an adjacent area. A high-shear mixer uses a rotating impeller or high-speed rotor, or a series of such impellers or inline rotors, usually powered by an electric motor, to " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixture
In chemistry, a mixture is a material made up of two or more different chemical substances which can be separated by physical method. It is an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proportion. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the form of solutions, suspensions or colloids. Mixtures are one product of mechanically blending or mixing chemical substances such as elements and compounds, without chemical bonding or other chemical change, so that each ingredient substance retains its own chemical properties and makeup. Despite the fact that there are no chemical changes to its constituents, the physical properties of a mixture, such as its melting point, may differ from those of the components. Some mixtures can be separated into their components by using physical (mechanical or thermal) means. Azeotropes are one kind of mixture that usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle
In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic particles like atoms and molecules, to macroscopic particles like powders and other granular materials. Particles can also be used to create scientific models of even larger objects depending on their density, such as humans moving in a crowd or celestial bodies in motion. The term ''particle'' is rather general in meaning, and is refined as needed by various scientific fields. Anything that is composed of particles may be referred to as being particulate. However, the noun '' particulate'' is most frequently used to refer to pollutants in the Earth's atmosphere, which are a suspension of unconnected particles, rather than a connected particle aggregation. Conceptual properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent
A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for Chemical polarity#Polarity of molecules, polar molecules, and the most common solvent used by living things; all the ions and proteins in a Cell (biology), cell are dissolved in water within the cell. Major uses of solvents are in paints, paint removers, inks, and dry cleaning. Specific uses for Organic compound, organic solvents are in dry cleaning (e.g. tetrachloroethylene); as paint thinners (toluene, turpentine); as nail polish removers and solvents of glue (acetone, methyl acetate, ethyl acetate); in spot removers (hexane, petrol ether); in detergents (D-limonene, citrus terpenes); and in perfumes (ethanol). Solvents find various applications in chemical, pharmaceutical, oil, and gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Settling
Settling is the process by which particulates move towards the bottom of a liquid and form a sediment. Particles that experience a force, either due to gravity or due to Centrifuge, centrifugal motion will tend to move in a uniform manner in the direction exerted by that force. For gravity settling, this means that the particles will tend to fall to the bottom of the vessel, forming sludge or slurry at the vessel base. Settling is an important operation in many applications, such as mining, wastewater and drinking water treatment, biological science, outer space, space rocket propellant, propellant reignition, and scooping. Physics For settling particles that are considered individually, i.e. dilute particle solutions, there are two main forces enacting upon any particle. The primary force is an applied force, such as gravity, and a Drag (physics), drag force that is due to the motion of the particle through the fluid. The applied force is usually not affected by the part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soot
Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. Soot is considered a hazardous substance with carcinogenic properties. Most broadly, the term includes all the particulate matter produced by this process, including black carbon and residual pyrolysed fuel particles such as coal, cenospheres, charred wood, and petroleum coke classified as cokes or char. It can include polycyclic aromatic hydrocarbons and heavy metals like mercury. Soot causes various types of cancer and lung disease. Terminology Definition Among scientists, exact definitions for soot vary, depending partly on their field. For example, atmospheric scientists may use a different definition compared to toxicologists. Soot's definition can also vary across time, and from paper to paper even among scientists in the same field. A common feature of the definitions is that soot is composed largely of carbon based particles resulting from the incomplete burni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Salt
Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking, cosmetics and for preserving food. It is also called bay salt, solar salt, or simply salt. Like mined rock salt, production of sea salt has been dated to prehistoric times. Composition Commercially available sea salts on the market today vary widely in their chemical composition. Although the principal component is sodium chloride, the remaining portion can range from less than 0.2 to 22% of other salts. These are mostly calcium, potassium, and magnesium salts of chloride and sulfate with substantially lesser amounts of many trace elements found in natural seawater. Though the composition of commercially available salt may vary, the ionic composition of natural saltwater is relatively constant. Historical production Sea salt is mentioned in the Vinaya Pitaka, a Buddhist scripture compiled in the mid-5th century BC. The principle of production is evaporation of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogenic
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of plants or animals. In context of molecular biology, biogenic substances are referred to as biomolecules. They are generally isolated and measured through the use of chromatography and mass spectrometry techniques. Additionally, the transformation and exchange of biogenic substances can by modelled in the environment, particularly their transport in waterways. The observation and measurement of biogenic substances is notably important in the fields of geology and biochemistry. A large proportion of isoprenoids and fatty acids in geological sediments are derived from plants and chlorophyll, and can be found in samples extending back to the Precambrian. These biogenic substances are capable of withstanding the diagenesis process in sediment, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfate
The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many are prepared from that acid. Spelling "Sulfate" is the spelling recommended by IUPAC, but "sulphate" was traditionally used in British English. Structure The sulfate anion consists of a central sulfur atom surrounded by four equivalent oxygen atoms in a tetrahedral arrangement. The symmetry of the isolated anion is the same as that of methane. The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogensulfate) ion, , which is in turn the conjugate base of , sulfuric acid. Organic sulfate esters, such as dimethyl sulfate, are covalent compounds and esters of sulfuric acid. The tetrahedral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
