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44-413: MCM-41 consists of a regular arrangement of cylindrical mesopores that form a one-dimensional pore system. It is characterized by an independently adjustable pore diameter, a sharp pore distribution, a large surface and a large pore volume. The pores are larger than with zeolites and the pore distribution can easily be adjusted. The mesopores have a diameter of 2 nm to 6.5 nm. Contrary to zeolites,

88-399: A hydrocarbon chain, which can be branched, linear, or aromatic. Fluorosurfactants have fluorocarbon chains. Siloxane surfactants have siloxane chains. Many important surfactants include a polyether chain terminating in a highly polar anionic group. The polyether groups often comprise ethoxylated ( polyethylene oxide -like) sequences inserted to increase the hydrophilic character of

132-437: A hydrophilic "water-seeking" group (the head ), and a hydrophobic "water-avoiding" group (the tail ). As a result, a surfactant contains both a water-soluble component and a water-insoluble component. Surfactants diffuse in water and get adsorbed at interfaces between air and water, or at the interface between oil and water in the case where water is mixed with oil. The water-insoluble hydrophobic group may extend out of

176-424: A quaternary nitrogen atom with a carboxylate group attached to it via a –CH 2 – link. At the present time, all compounds whose structure includes this motif are known as betaines. Betaines do not isomerize because the chemical groups attached to the nitrogen atom are not labile . These compounds may be classed as permanent zwitterions, as isomerisation to a molecule with no electrical charges does not occur, or

220-421: A zwitterion ( / ˈ t s v ɪ t ə ˌ r aɪ ə n / TSVIT -ə-ry-ən ; from German Zwitter [ˈtsvɪtɐ]  ' hermaphrodite '), also called an inner salt or dipolar ion , is a molecule that contains an equal number of positively and negatively charged functional groups . With amino acids , for example, in solution a chemical equilibrium will be established between

264-742: A liquid and a gas , or a liquid and a solid . The word "surfactant" is a blend of surf ace- act ive a ge nt , coined in 1950 . As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt. Surfactants are among the most widespread and commercially important chemicals. Private households as well as many industries use them in large quantities as detergents and cleaning agents , but also for example as emulsifiers , wetting agents, foaming agents , antistatic additives, or dispersants . Surfactants occur naturally in traditional plant-based detergents, e.g. horse chestnuts or soap nuts ; they can also be found in

308-606: A net positive, or negative, charge. If the charge is negative, the surfactant is more specifically called anionic ; if the charge is positive, it is called cationic . If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic , or amphoteric . Commonly encountered surfactants of each type include: Anionic surfactants contain anionic functional groups at their head, such as sulfate , sulfonate , phosphate , and carboxylates . Prominent alkyl sulfates include ammonium lauryl sulfate , sodium lauryl sulfate (sodium dodecyl sulfate, SLS, or SDS), and

352-423: A p K a value of 4.88. Sulfamic acid crystallizes in the zwitterion form. In crystals of anthranilic acid there are two molecules in the unit cell . One molecule is in the zwitterion form, the other is not. In the solid state, H 4 EDTA is a zwitterion with two protons having been transferred from carboxylic acid groups to the nitrogen atoms. In psilocybin , the proton on the dimethyl amino group

396-476: A phosphate anion with an amine or ammonium, such as the phospholipids phosphatidylserine , phosphatidylethanolamine , phosphatidylcholine , and sphingomyelins . Lauryldimethylamine oxide and myristamine oxide are two commonly used zwitterionic surfactants of the tertiary amine oxides structural type. Non-ionic surfactants have covalently bonded oxygen-containing hydrophilic groups, which are bonded to hydrophobic parent structures. The water-solubility of

440-413: A surfactant produced in the liver, play an important role in digestion. Most anionic and non-ionic surfactants are non-toxic, having LD50 comparable to table salt . The toxicity of quaternary ammonium compounds , which are antibacterial and antifungal , varies. Dialkyldimethylammonium chlorides ( DDAC , DSDMAC ) used as fabric softeners have high LD50 (5 g/kg) and are essentially non-toxic, while

484-400: A surfactant. Polypropylene oxides conversely, may be inserted to increase the lipophilic character of a surfactant. Surfactant molecules have either one tail or two; those with two tails are said to be double-chained . Most commonly, surfactants are classified according to polar head group. A non-ionic surfactant has no charged groups in its head. The head of an ionic surfactant carries

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528-647: A variety of chemical species by dissociating aggregates and unfolding proteins. Popular surfactants in the biochemistry laboratory are sodium lauryl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB). Detergents are key reagents to extract protein by lysis of the cells and tissues: They disorganize the membrane's lipid bilayer (SDS, Triton X-100 , X-114 , CHAPS , DOC , and NP-40 ), and solubilize proteins. Milder detergents such as octyl thioglucoside , octyl glucoside or dodecyl maltoside are used to solubilize membrane proteins such as enzymes and receptors without denaturing them. Non-solubilized material

572-403: Is labile and may jump to the phosphate group to form a compound which is not a zwitterion. Insight to the equilibrium in solution may be gained from the results of theoretical calculations. For example, pyridoxal phosphate, a form of vitamin B 6 , in aqueous solution is predicted to have an equilibrium favoring a tautomeric form in which a proton is transferred from the phenolic -OH group to

616-412: Is estimated at 15 million tons per year, of which about half are soaps . Other surfactants produced on a particularly large scale are linear alkylbenzene sulfonates (1.7 million tons/y), lignin sulfonates (600,000 tons/y), fatty alcohol ethoxylates (700,000 tons/y), and alkylphenol ethoxylates (500,000 tons/y). In the bulk aqueous phase, surfactants form aggregates, such as micelles , where

660-414: Is harvested by centrifugation or other means. For electrophoresis , for example, proteins are classically treated with SDS to denature the native tertiary and quaternary structures , allowing the separation of proteins according to their molecular weight . Detergents have also been used to decellularise organs. This process maintains a matrix of proteins that preserves the structure of the organ and often

704-446: Is independent of pH . It has been suggested, on the basis of theoretical analysis, that the zwitterion is stabilized in aqueous solution by hydrogen bonding with solvent water molecules. Analysis of neutron diffraction data for glycine showed that it was in the zwitterionic form in the solid state and confirmed the presence of hydrogen bonds. Theoretical calculations have been used to show that zwitterions may also be present in

748-430: Is ongoing in how surfactants arrange themselves on the surface of the quantum dots. Surfactants play an important role in droplet-based microfluidics in the stabilization of the droplets, and the prevention of the fusion of droplets during incubation. Janus-type material is used as a surfactant-like heterogeneous catalyst for the synthesis of adipic acid. Agents that increase surface tension are "surface active" in

792-457: Is produced in the lungs in order to facilitate breathing by increasing total lung capacity , and lung compliance . In respiratory distress syndrome or RDS, surfactant replacement therapy helps patients have normal respiration by using pharmaceutical forms of the surfactants. One example of a pharmaceutical pulmonary surfactant is Survanta ( beractant ) or its generic form Beraksurf, produced by Abbvie and Tekzima respectively. Bile salts ,

836-545: Is the hydrophilic-lipophilic balance (HLB). Surfactants reduce the surface tension of water by adsorbing at the liquid-air interface. The relation that links the surface tension and the surface excess is known as the Gibbs isotherm . The dynamics of surfactant adsorption is of great importance for practical applications such as in foaming, emulsifying or coating processes, where bubbles or drops are rapidly generated and need to be stabilized. The dynamics of absorption depend on

880-506: Is thought to be an endocrine disruptor . Interest in biodegradable surfactants has led to much interest in "biosurfactants" such as those derived from amino acids. Biobased surfactants can offer improved biodegradation. However, whether surfactants damage the cells of fish or cause foam mountains on bodies of water depends primarily on their chemical structure and not on whether the carbon originally used came from fossil sources, carbon dioxide or biomass. Zwitterion In chemistry ,

924-407: Is very slow. Other examples of permanent zwitterions include phosphatidylcholines, which also contain a quaternary nitrogen atom, but with a negatively-charged phosphate group in place of a carboxylate group; sulfobetaines , which contain a quaternary nitrogen atom and a negatively charged sulfonate group; and pulmonary surfactants such as dipalmitoylphosphatidylcholine . Lauramidopropyl betaine

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968-480: The diffusion coefficient of the surfactant. As the interface is created, the adsorption is limited by the diffusion of the surfactant to the interface. In some cases, there can exist an energetic barrier to adsorption or desorption of the surfactant. If such a barrier limits the adsorption rate, the dynamics are said to be ‘kinetically limited'. Such energy barriers can be due to steric or electrostatic repulsions . The surface rheology of surfactant layers, including

1012-551: The disinfectant alkylbenzyldimethylammonium chloride has an LD50 of 0.35 g/kg. Prolonged exposure to surfactants can irritate and damage the skin because surfactants disrupt the lipid membrane that protects skin and other cells. Skin irritancy generally increases in the series non-ionic, amphoteric, anionic, cationic surfactants. Surfactants are routinely deposited in numerous ways on land and into water systems, whether as part of an intended process or as industrial and household waste. Anionic surfactants can be found in soils as

1056-417: The "parent" molecule and the zwitterion. Betaines are zwitterions that cannot isomerize to an all-neutral form, such as when the positive charge is located on a quaternary ammonium group. Similarly, a molecule containing a phosphonium group and a carboxylate group cannot isomerize. Tautomerism of amino acids follows this stoichiometry: The ratio of the concentrations of the two species in solution

1100-480: The bulk water phase into a non-water phase such as air or oil phase, while the water-soluble head group remains bound in the water phase. The hydrophobic tail may be either lipophilic ("oil-seeking") or lipophobic ("oil-avoiding") depending on its chemistry. Hydrocarbon groups are usually lipophilic, for use in soaps and detergents, while fluorocarbon groups are lipophobic, for use in repelling stains or reducing surface tension. World production of surfactants

1144-630: The choice is primarily governed having regard to the costs of special properties (e.g., effectiveness and efficiency, toxicity, dermatological compatibility, biodegradability ) or permission for use in food. Fatty acid ethoxylates are a class of very versatile surfactants, which combine in a single molecule the characteristic of a weakly anionic, pH-responsive head group with the presence of stabilizing and temperature responsive ethyleneoxide units. Spans : Tweens : Surfactants are usually organic compounds that are akin to amphiphilic , which means that this molecule, being as double-agent, each contains

1188-472: The displacement of air from the matrix of cotton pads and bandages so that medicinal solutions can be absorbed for application to various body areas. They also act to displace dirt and debris by the use of detergents in the washing of wounds and via the application of medicinal lotions and sprays to surface of skin and mucous membranes. Surfactants enhance remediation via soil washing, bioremediation, and phytoremediation. In solution, detergents help solubilize

1232-497: The elasticity and viscosity of the layer, play an important role in the stability of foams and emulsions. Interfacial and surface tension can be characterized by classical methods such as the -pendant or spinning drop method . Dynamic surface tensions, i.e. surface tension as a function of time, can be obtained by the maximum bubble pressure apparatus The structure of surfactant layers can be studied by ellipsometry or X-ray reflectivity . Surface rheology can be characterized by

1276-535: The environment, for example laundry detergents in waters, their biodegradation is of great interest. Attracting much attention is the non-biodegradability and extreme persistence of fluorosurfactant , e.g. perfluorooctanoic acid (PFOA). Strategies to enhance degradation include ozone treatment and biodegradation. Two major surfactants, linear alkylbenzene sulfonates (LAS) and the alkyl phenol ethoxylates (APE) break down under aerobic conditions found in sewage treatment plants and in soil to nonylphenol , which

1320-427: The framework of MCM-41 has no bronsted acid centers because there is no aluminium contained in the lattice. The acidity of alumina-doped MCM-41 therefore is comparable to that of the amorphous alumosilicates. MCM-41 is not hydrothermally stable because of the slight wall thickness and the low degree of cross-linking of the silicate units. To achieve a defined pore diameter surfactants are used that form micelles in

1364-407: The gas phase for some cases different from the simple carboxylic acid-to-amine transfer. The p K a values for deprotonation of the common amino acids span the approximate range 2.15 ± 0.2 . This is also consistent with the zwitterion being the predominant isomer that is present in an aqueous solution. For comparison, the simple carboxylic acid propionic acid ( CH 3 CH 2 CO 2 H ) has

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1408-409: The hydrophobic tails form the core of the aggregate and the hydrophilic heads are in contact with the surrounding liquid. Other types of aggregates can also be formed, such as spherical or cylindrical micelles or lipid bilayers . The shape of the aggregates depends on the chemical structure of the surfactants, namely the balance in size between the hydrophilic head and hydrophobic tail. A measure of this

1452-469: The literal sense but are not called surfactants as their effect is opposite to the common meaning. A common example of surface tension increase is salting out : adding an inorganic salt to an aqueous solution of a weakly polar substance will cause the substance to precipitate. The substance may itself be a surfactant, which is one of the reasons why many surfactants are ineffective in sea water. The human body produces diverse surfactants. Pulmonary surfactant

1496-422: The microvascular network. The process has been successfully used to prepare organs such as the liver and heart for transplant in rats. Pulmonary surfactants are also naturally secreted by type II cells of the lung alveoli in mammals . Surfactants are used with quantum dots in order to manipulate their growth, assembly, and electrical properties, in addition to mediating reactions on their surfaces. Research

1540-401: The nitrogen atom. Because tautomers are different compounds, they sometimes have different enough structures that they can be detected independently in their mixture. This allows experimental analysis of the equilibrium. The compound trimethylglycine , which was isolated from sugar beet , was named as "betaine". Later, other compounds were discovered that contain the same structural motif,

1584-470: The ocean at the leak and on the sea-water's surface. The apparent theory was that the surfactants isolate droplets of oil, making it easier for petroleum-consuming microbes to digest the oil. The active ingredient in Corexit is dioctyl sodium sulfosuccinate (DOSS), sorbitan monooleate (Span 80), and polyoxyethylenated sorbitan monooleate ( Tween-80 ). Because of the volume of surfactants released into

1628-1048: The oscillating drop method or shear surface rheometers such as double-cone, double-ring or magnetic rod shear surface rheometer. Surfactants play an important role as cleaning, wetting , dispersing , emulsifying , foaming and anti-foaming agents in many practical applications and products, including detergents , fabric softeners , motor oils , emulsions , soaps , paints , adhesives , inks , anti-fogs , ski waxes , snowboard wax, deinking of recycled papers , in flotation, washing and enzymatic processes, and laxatives . Also agrochemical formulations such as herbicides (some), insecticides , biocides (sanitizers), and spermicides ( nonoxynol-9 ). Personal care products such as cosmetics , shampoos , shower gel , hair conditioners , and toothpastes . Surfactants are used in firefighting (to make "wet water" that more quickly soaks into flammable materials ) and pipelines (liquid drag reducing agents). Alkali surfactant polymers are used to mobilize oil in oil wells . Surfactants act to cause

1672-411: The oxygen groups is the result of hydrogen bonding . Hydrogen bonding decreases with increasing temperature, and the water solubility of non-ionic surfactants therefore decreases with increasing temperature. Non-ionic surfactants are less sensitive to water hardness than anionic surfactants, and they foam less strongly. The differences between the individual types of non-ionic surfactants are slight, and

1716-951: The related alkyl-ether sulfates sodium laureth sulfate (sodium lauryl ether sulfate or SLES), and sodium myreth sulfate . Others include: Carboxylates are the most common surfactants and comprise the carboxylate salts (soaps), such as sodium stearate . More specialized species include sodium lauroyl sarcosinate and carboxylate-based fluorosurfactants such as perfluorononanoate , perfluorooctanoate (PFOA or PFO). pH-dependent primary, secondary, or tertiary amines ; primary and secondary amines become positively charged at pH < 10: octenidine dihydrochloride . Permanently charged quaternary ammonium salts : cetrimonium bromide (CTAB), cetylpyridinium chloride (CPC), benzalkonium chloride (BAC), benzethonium chloride (BZT), dimethyldioctadecylammonium chloride , and dioctadecyldimethylammonium bromide (DODAB). Zwitterionic ( ampholytic ) surfactants have both cationic and anionic centers attached to

1760-496: The result of sewage sludge application, wastewater irrigation, and remediation processes. Relatively high concentrations of surfactants together with multimetals can represent an environmental risk. At low concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility. In the case of the Deepwater Horizon oil spill , unprecedented amounts of Corexit were sprayed directly into

1804-452: The same molecule. The cationic part is based on primary, secondary, or tertiary amines or quaternary ammonium cations. The anionic part can be more variable and include sulfonates, as in the sultaines CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) and cocamidopropyl hydroxysultaine . Betaines such as cocamidopropyl betaine have a carboxylate with the ammonium. The most common biological zwitterionic surfactants have

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1848-618: The secretions of some caterpillars. Today one of the most commonly used anionic surfactants, linear alkylbenzene sulfates (LAS), are produced from petroleum products . However, surfactants are increasingly produced in whole or in part from renewable biomass , like sugar, fatty alcohol from vegetable oils, by-products of biofuel production, or other biogenic material. Most surfactants are organic compounds with hydrophilic "heads" and hydrophobic "tails." The "heads" of surfactants are polar and may or may not carry an electrical charge. The "tails" of most surfactants are fairly similar, consisting of

1892-429: The silicon atoms are bridged by oxygen atoms. The organic template is oxidized and disappears. MCM-41, as the zeolites , are widely used as catalytic cracking . MCM-41 type materials have been widely used as support of heterogeneous catalysts and also used for separations. Surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids ,

1936-401: The synthesis solution. These micelles form templates that help build up the mesoporous framework. For MCM-41 mostly cetyltrimethylammonium bromide (CTAB) is used. [REDACTED] The surfactant first forms rod-like micelles that subsequently align into hexagonal arrays. After adding silica species these cover the rods. Later, calcination leads to a condensation of the silanol groups so that

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