Surfactant

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Schematic diagram of a micelle of oil in aqueous suspension, such as might occur in an emulsion of oil in water. In this example, the surfactant molecules' oil-soluble tails project into the oil (blue), while the water-soluble ends remain in contact with the water phase (red). A lipid micelle.png
Schematic diagram of a micelle of oil in aqueous suspension, such as might occur in an emulsion of oil in water. In this example, the surfactant molecules' oil-soluble tails project into the oil (blue), while the water-soluble ends remain in contact with the water phase (red).

Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word "surfactant" is a blend of surface-active agent, [1] coined in 1950 . [2] 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.

Contents

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 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. [3]

Classification

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 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 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. [4]

Surfactant classification according to the composition of their head: non-ionic, anionic, cationic, amphoteric. TensideHyrophilHydrophob.png
Surfactant classification according to the composition of their head: non-ionic, anionic, cationic, amphoteric.

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 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: sulfate, sulfonate, and phosphate, carboxylate derivatives

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 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).

Cationic head groups

pH-dependent primary, secondary, or tertiary amines; primary and secondary amines become positively charged at pH < 10: [5] 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 surfactants

Zwitterionic (ampholytic) surfactants have both cationic and anionic centers attached to 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 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

Non-ionic surfactants have covalently bonded oxygen-containing hydrophilic groups, which are bonded to hydrophobic parent structures. The water-solubility of 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 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. [6]

Ethoxylates

Fatty alcohol ethoxylates
Alkylphenol ethoxylates (APEs or APEOs)
Fatty acid ethoxylates

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. [7]

Special ethoxylated fatty esters and oils
Ethoxylated amines and/or fatty acid amides
Terminally blocked ethoxylates

Fatty acid esters of polyhydroxy compounds

Fatty acid esters of glycerol
Fatty acid esters of sorbitol

Spans:

Tweens:

Fatty acid esters of sucrose
Alkyl polyglucosides

Other classifications

Gemini amino acid-based surfactant (based on cysteine) Gemini surfactant.png
Gemini amino acid-based surfactant (based on cysteine)

Composition and structure

Schematic diagram of a micelle - the lipophilic tails of the surfactant ions remain inside the oil because they interact more strongly with oil than with water. The polar "heads" of the surfactant molecules coating the micelle interact more strongly with water, so they form a hydrophilic outer layer that forms a barrier between micelles. This inhibits the oil droplets, the hydrophobic cores of micelles, from merging into fewer, larger droplets ("emulsion breaking") of the micelle. The compounds that coat a micelle are typically amphiphilic in nature, meaning that micelles may be stable either as droplets of aprotic solvents such as oil in water, or as protic solvents such as water in oil. When the droplet is aprotic it is sometimes known as a reverse micelle. Micelle scheme-en.svg
Schematic diagram of a micelle  – the lipophilic tails of the surfactant ions remain inside the oil because they interact more strongly with oil than with water. The polar "heads" of the surfactant molecules coating the micelle interact more strongly with water, so they form a hydrophilic outer layer that forms a barrier between micelles. This inhibits the oil droplets, the hydrophobic cores of micelles, from merging into fewer, larger droplets ("emulsion breaking") of the micelle. The compounds that coat a micelle are typically amphiphilic in nature, meaning that micelles may be stable either as droplets of aprotic solvents such as oil in water, or as protic solvents such as water in oil. When the droplet is aprotic it is sometimes known as a reverse micelle.

Surfactants are usually organic compounds that are akin to amphiphilic, which means that this molecule, being as double-agent, each contains a hydrophilic "water-seeking" group (the head), and a hydrophobic "water-avoiding" group (the tail). [9] 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 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 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). [6]

Sodium stearate, the most common component of most soap, which comprises about 50% of commercial surfactants Sodium stearate.svg
Sodium stearate, the most common component of most soap, which comprises about 50% of commercial surfactants
4-(5-Dodecyl) benzenesulfonate, a linear dodecylbenzenesulfonate, one of the most common surfactants Sodium dodecylbenzenesulfonate skeletal.svg
4-(5-Dodecyl) benzenesulfonate, a linear dodecylbenzenesulfonate, one of the most common surfactants

Structure of surfactant phases in water

In the bulk aqueous phase, surfactants form aggregates, such as micelles, where 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 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.

Dynamics of surfactants at interfaces

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 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 the elasticity and viscosity of the layer, play an important role in the stability of foams and emulsions.

Characterization of interfaces and surfactant layers

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 the oscillating drop method or shear surface rheometers such as double-cone, double-ring or magnetic rod shear surface rheometer.

Applications

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). [10] 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 [11] [12] ) and pipelines (liquid drag reducing agents). Alkali surfactant polymers are used to mobilize oil in oil wells.

Surfactants act to cause 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 [13] and via the application of medicinal lotions and sprays to surface of skin and mucous membranes. [14] Surfactants enhance remediation via soil washing, bioremediation, and phytoremediation. [15]

Detergents in biochemistry and biotechnology

In solution, detergents help solubilize 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 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 the microvascular network. The process has been successfully used to prepare organs such as the liver and heart for transplant in rats. [16] Pulmonary surfactants are also naturally secreted by type II cells of the lung alveoli in mammals.

Quantum dot preparation

Surfactants are used with quantum dots in order to manipulate their growth, [17] assembly, and electrical properties, in addition to mediating reactions on their surfaces. Research is ongoing in how surfactants arrange themselves on the surface of the quantum dots. [18]

Surfactants in droplet-based microfluidics

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. [19]

Heterogeneous catalysis

Janus-type material is used as a surfactant-like heterogeneous catalyst for the synthesis of adipic acid. [20]

Increased surface tension

Agents that increase surface tension are "surface active" in 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.

In biology

Phosphatidylcholine, found in lecithin, is a pervasive biological surfactant. Shown in @media screen{html.skin-theme-clientpref-night .mw-parser-output div:not(.notheme)>.tmp-color,html.skin-theme-clientpref-night .mw-parser-output p>.tmp-color,html.skin-theme-clientpref-night .mw-parser-output table:not(.notheme) .tmp-color{color:inherit!important}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output div:not(.notheme)>.tmp-color,html.skin-theme-clientpref-os .mw-parser-output p>.tmp-color,html.skin-theme-clientpref-os .mw-parser-output table:not(.notheme) .tmp-color{color:inherit!important}} red - choline and phosphate group; black - glycerol; green - monounsaturated fatty acid; blue - saturated fatty acid. 1-Oleoyl-2-almitoyl-phosphatidylcholine Structural Formulae V.1.png
Phosphatidylcholine, found in lecithin, is a pervasive biological surfactant. Shown in red – choline and phosphate group; black – glycerol; green – monounsaturated fatty acid; blue – saturated fatty acid.

The human body produces diverse surfactants. Pulmonary surfactant 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, a surfactant produced in the liver, play an important role in digestion. [21]

Safety and environmental risks

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 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. [6]

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. [22] [23] [24]

Anionic surfactants can be found in soils as 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. [25] [26]

In the case of the Deepwater Horizon oil spill, unprecedented amounts of Corexit were sprayed directly into 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). [27] [28]

Biodegradation

Because of the volume of surfactants released into 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). [29] Strategies to enhance degradation include ozone treatment and biodegradation. [30] [31] 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 is thought to be an endocrine disruptor. [32] [33] Interest in biodegradable surfactants has led to much interest in "biosurfactants" such as those derived from amino acids. [34] 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. [3]

See also

Related Research Articles

Sodium laureth sulfate (SLES), an accepted contraction of sodium lauryl ether sulfate (SLES), also called sodium alkylethersulfate, is an anionic detergent and surfactant found in many personal care products and for industrial uses. SLES is an inexpensive and very effective foaming agent. SLES, sodium lauryl sulfate (SLS), ammonium lauryl sulfate (ALS), and sodium pareth sulfate are surfactants that are used in many cosmetic products for their cleaning and emulsifying properties. It is derived from palm kernel oil or coconut oil. In herbicides, it is used as a surfactant to improve absorption of the herbicidal chemicals and reduces time the product takes to be rainfast, when enough of the herbicidal agent will be absorbed.

Sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS), sometimes written sodium laurilsulfate, is an organic compound with the formula CH3(CH2)11OSO3Na and structure H3C−(CH2)11−O−S(=O)2−O−Na+. It is an anionic surfactant used in many cleaning and hygiene products. This compound is the sodium salt of the 12-carbon organosulfate. Its hydrocarbon tail combined with a polar "headgroup" give the compound amphiphilic properties that make it useful as a detergent. SDS is also component of mixtures produced from inexpensive coconut and palm oils. SDS is a common component of many domestic cleaning, personal hygiene and cosmetic, pharmaceutical, and food products, as well as of industrial and commercial cleaning and product formulations.

<span class="mw-page-title-main">Detergent</span> Surfactants with cleansing properties

A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more soluble in hard water, because the polar sulfonate is less likely than the polar carboxylate to bind to calcium and other ions found in hard water.

Lipophilicity is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are called lipophilic. Such non-polar solvents are themselves lipophilic, and the adage "like dissolves like" generally holds true. Thus lipophilic substances tend to dissolve in other lipophilic substances, whereas hydrophilic ("water-loving") substances tend to dissolve in water and other hydrophilic substances.

Ammonium lauryl sulfate (ALS) is the common name for ammonium dodecyl sulfate (CH3(CH2)10CH2OSO3NH4). The anion consists of a nonpolar hydrocarbon chain and a polar sulfate end group. The combination of nonpolar and polar groups confers surfactant properties to the anion: it facilitates dissolution of both polar and non-polar materials. This salt is classified as a sulfate ester. It is made from coconut or palm kernel oil for use primarily in shampoos and body-wash as a foaming agent. Lauryl sulfates are very high-foam surfactants that disrupt the surface tension of water in part by forming micelles at the surface-air interface.

In organic chemistry, ethoxylation is a chemical reaction in which ethylene oxide adds to a substrate. It is the most widely practiced alkoxylation, which involves the addition of epoxides to substrates.

A fabric softener or fabric conditioner is a conditioner applied to laundry after it has been washed in a washing machine. A similar, more dilute preparation meant to be applied to dry fabric is known as a wrinkle releaser.

In colloidal and surface chemistry, the critical micelle concentration (CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system will form micelles.

A foaming agent is a material such as a surfactant or a blowing agent that facilitates the formation of foam. A surfactant, when present in small amounts, reduces surface tension of a liquid or increases its colloidal stability by inhibiting coalescence of bubbles. A blowing agent is a gas that forms the gaseous part of the foam.

<span class="mw-page-title-main">Laundry detergent</span> Type of detergent used for cleaning laundry

Laundry detergent is a type of detergent used for cleaning dirty laundry (clothes). Laundry detergent is manufactured in powder and liquid form.

<span class="mw-page-title-main">Hydroxysultaine</span> Class of chemical compounds

Hydroxysultaines are chemical compounds used in high-foaming shampoos, bath products and shower gels especially in conjunction with ether sulfates and alkyl sulfates. They are also used in industrial applications where high, stable foam is required. Chemically, hydroxysultaines are zwitterionic, typically containing covalently linked positive and negative ions.

Sodium myreth sulfate is a mixture of organic compounds with both detergent and surfactant properties. It is found in many personal care products such as soaps, shampoos, and toothpaste. It is an inexpensive and effective foaming agent. Typical of many detergents, sodium myreth sulfate consists of several closely related compounds. Sometimes the number of ethylene glycol ether units (n) is specified in the name as myreth-n sulfate, for example myreth-2 sulfate.

<span class="mw-page-title-main">Amphiphile</span> Chemical compound with both hydrophilic and lipophilic properties

In chemistry, an amphiphile, or amphipath, is a chemical compound possessing both hydrophilic and lipophilic properties. Such a compound is called amphiphilic or amphipathic. Amphiphilic compounds include surfactants and detergents. The phospholipid amphiphiles are the major structural component of cell membranes.

<span class="mw-page-title-main">Organosulfate</span> Organic compounds of the form R–O–SO₃ (charge –1)

In organosulfur chemistry, organosulfates are a class of organic compounds sharing a common functional group with the structure R−O−SO−3. The SO4 core is a sulfate group and the R group is any organic residue. All organosulfates are formally esters derived from alcohols and sulfuric acid although many are not prepared in this way. Many sulfate esters are used in detergents, and some are useful reagents. Alkyl sulfates consist of a hydrophobic hydrocarbon chain, a polar sulfate group and either a cation or amine to neutralize the sulfate group. Examples include: sodium lauryl sulfate and related potassium and ammonium salts.

<span class="mw-page-title-main">Cleaning agent</span> Substance used to remove dirt or other contaminants

Cleaning agents or hard-surface cleaners are substances used to remove dirt, including dust, stains, foul odors, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing offensive odors, and avoiding the spread of dirt and contaminants to oneself and others. Some cleaning agents can kill bacteria and clean at the same time. Others, called degreasers, contain organic solvents to help dissolve oils and fats.

Paint has four major components: pigments, binders, solvents, and additives. Pigments serve to give paint its color, texture, toughness, as well as determining if a paint is opaque or not. Common white pigments include titanium dioxide and zinc oxide. Binders are the film forming component of a paint as it dries and affects the durability, gloss, and flexibility of the coating. Polyurethanes, polyesters, and acrylics are all examples of common binders. The solvent is the medium in which all other components of the paint are dissolved and evaporates away as the paint dries and cures. The solvent also modifies the curing rate and viscosity of the paint in its liquid state. There are two types of paint: solvent-borne and water-borne paints. Solvent-borne paints use organic solvents as the primary vehicle carrying the solid components in a paint formulation, whereas water-borne paints use water as the continuous medium. The additives that are incorporated into paints are a wide range of things which impart important effects on the properties of the paint and the final coating. Common paint additives are catalysts, thickeners, stabilizers, emulsifiers, texturizers, biocides to fight bacterial growth, etc.

<span class="mw-page-title-main">Oil dispersant</span> Mixture of emulsifiers and solvents used to treat oil spills

An oil dispersant is a mixture of emulsifiers and solvents that helps break oil into small droplets following an oil spill. Small droplets are easier to disperse throughout a water volume, and small droplets may be more readily biodegraded by microbes in the water. Dispersant use involves a trade-off between exposing coastal life to surface oil and exposing aquatic life to dispersed oil. While submerging the oil with dispersant may lessen exposure to marine life on the surface, it increases exposure for animals dwelling underwater, who may be harmed by toxicity of both dispersed oil and dispersant. Although dispersant reduces the amount of oil that lands ashore, it may allow faster, deeper penetration of oil into coastal terrain, where it is not easily biodegraded.

<span class="mw-page-title-main">Alkylbenzene sulfonate</span> Class of chemical compounds

Alkylbenzene sulfonates are a class of anionic surfactants, consisting of a hydrophilic sulfonate head-group and a hydrophobic alkylbenzene tail-group. Along with sodium laureth sulfate, they are one of the oldest and most widely used synthetic detergents and may be found in numerous personal-care products and household-care products . They were introduced in the 1930s in the form of branched alkylbenzene sulfonates (BAS). However following environmental concerns these were replaced with linear alkylbenzene sulfonates (LAS) during the 1960s. Since then production has increased significantly from about one million tons in 1980, to around 3.5 million tons in 2016, making them most produced anionic surfactant after soaps.

Wastewater comes out of the laundry process with additional energy (heat), lint, soil, dyes, finishing agents, and other chemicals from detergents. Some laundry wastewater goes directly into the environment, due to the flaws of water infrastructure. The majority goes to sewage treatment plants before flowing into the environment. Some chemicals remain in the water after treatment, which may contaminate the water system. Some have argued they can be toxic to wildlife, or can lead to eutrophication.

α-Olefin sulfonate Class of chemical compounds

α-Olefin sulfonates are a group of anionic surfactants, which are used as detergents. The compounds contain a - mostly linear, primary - alkyl R and a monovalent cation M, preferably sodium. The most frequently used example of this group of substances is sodium α-olefin sulfonate.

References

  1. ↑ Rosen MJ, Kunjappu JT (2012). Surfactants and Interfacial Phenomena (4th ed.). Hoboken, New Jersey: John Wiley & Sons. p. 1. ISBN   978-1-118-22902-6. Archived from the original on 8 January 2017. A surfactant (a contraction of surface-active agent) is a substance that, when present at low concentration in a system, has the property of adsorbing onto the surfaces or interfaces of the system and of altering to a marked degree the surface or interfacial free energies of those surfaces (or interfaces).
  2. ↑ "surfactant" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.) – "A new word, Surfactants, has been coined by Antara Products, General Aniline & Film Corporation, and has been presented to the chemical industry to cover all materials that have surface activity, including wetting agents, dispersants, emulsifiers, detergents and foaming agents."
  3. 1 2 "Biobased Surfactants Market Report: Market Analysis". Ceresana Market Research. Retrieved 5 January 2024.
  4. ↑ "Surfactant | Defination, Classification, Properties & Uses". www.esteem-india.com.
  5. ↑ Reich, Hans J. (2012). "Bordwell pKa Table (Acidity in DMSO)". University of Wisconsin. Archived from the original on 27 December 2012. Retrieved 2 April 2013.
  6. 1 2 3 Kurt Kosswig "Surfactants" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, 2005, Weinheim. doi : 10.1002/14356007.a25_747
  7. ↑ Chiappisi, Leonardo (December 2017). "Polyoxyethylene alkyl ether carboxylic acids: An overview of a neglected class of surfactants with multiresponsive properties". Advances in Colloid and Interface Science. 250: 79–94. doi:10.1016/j.cis.2017.10.001. PMID   29056232.
  8. 1 2 Bordes, Romain; Holmberg, Krister (28 March 2015). "Amino acid-based surfactants – do they deserve more attention?". Advances in Colloid and Interface Science . 222: 79–91. doi:10.1016/j.cis.2014.10.013.
  9. ↑ "Bubbles, Bubbles, Everywhere, But Not a Drop to Drink". The Lipid Chronicles. 11 November 2011. Archived from the original on 26 April 2012. Retrieved 1 August 2012.
  10. ↑ Paria, Santanu (2008). "Surfactant-enhanced remediation of organic contaminated soil and water". Advances in Colloid and Interface Science. 138 (1): 24–58. doi:10.1016/j.cis.2007.11.001. PMID   18154747.
  11. ↑ Better Than Water? How Wet Water Outperforms Regular Water in Firefighting
  12. ↑ Firefighters Turn to "Wet Water" to Fight Larger, More Complex Fires
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