A surfactant or surface active agent is a substance that when dissolved in water gives a product the ability to remove dirty from surface such as the human skin textiles and other solid.
Each surfactant molecule has a hydrophilic head that is attracted to water molecule and a hydrophobic tail that repels water molecule and a simultanesously attaches itself to oil and grease in dirt . These opposing forces loosen the dirt and suspend in the water.
"Surfactants, also known as wetting agents, lower the surface tension of a liquid, allowing easier spreading, and the interfacial tension between two liquids. The term surfactant is a contraction of "Surface active agent". Surfactants are usually organic compounds that are amphipathic, meaning they contain both hydrophobic groups (their "tails") and hydrophilic groups (their "heads"). Therefore, they are typically sparingly soluble in both organic solvents and water. Surfactants reduce the surface tension of water by adsorbing at the air-water interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. Many surfactants can also assemble in the bulk solution into aggregates that are known as micelles. The concentration at which surfactants begin to form micelles is known as the critical micelle concentration or CMC. When micelles form in water, their tails form a core that is like an oil droplet, and their (ionic) heads form an outer shell that maintains favorable contact with water. When surfactants assemble in oil, the aggregate is referred to as a reverse micelle. In a reverse micelle, the heads are in the core and the tails maintain favorable contact with oil."
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Surfactants are used to enable substances to mix with water, they have a water hating and water loving structure, the water loving part interferes with water, and kind of acts like a bodyguard to protect the water hating part. So that, if water hating substances were to be added, the bodyguards-these being the water liking aspect of the surfactant, would allow the water hating aspects of the surfactant structure to interact with the water hating substances, so that all 3 entities- water, surfactant, water hating substance, could interact at peace in water. It's like a mediator. monkeys are awesome
Surfactant activity :--- Surfactant provide a variety of functionalise in herbicibal formulatiss .They may function as an activator adjuvant a sprayer modifier adjuvant a utility modifier or an emulsifying agent or as a dispering agent for Weetable powder .Regardless of the usage the surface active properties that are determine in herbicide ,dispersion choices are surface tension wetting properties ,contact angle micellele formation and hydrphollic lip ophhilic balance .
Surfactants are also referred to as wetting agents and foamers. Surfactants lower the surface tension of the medium in which it is dissolved. By lowering this interfacial tension between two media or interfaces (e.g. air/water, water/stain, stain/fabric) the surfactant plays a key role in the removal and suspension of dirt. The lower surface tension of the water makes it easier to lift dirt and grease off of dirty dishes, clothes and other surfaces, and help to keep them suspended in the dirty water. The water-loving or hydrophilic head remains in the water and it pulls the stains towards the water, away from the fabric. The surfactant molecules surround the stain particles, break them up and force them away from the surface of the fabric. They then suspend the stain particles in the wash water to remove them.
Vanvalkenburg give an adequate discussion of the theoretical back ground of surface properties as they relate to herbicide dispersion.In that dissusion it was found necessary to cover the surface tension of addition so the liquid could be emulusified with an ordinary insoluble second liquid such surface tension lowering was also effective in permitting the dispersion of paticleculate solid into liquid phase.
Flurinated surfactants are the superfactal . The flurocarban hydrophote can lower the surface tension of water below the lower limit reached by hydrocarbon type surfactant.
Like all surfactant fluorinated surfactant are either ionic or noanionic unlike non-ionic surfactants ,ionic surfactants can dissociates into ion in an aqueous medium.
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The hydrophobic part can being to a
- Positive charged
- Negative charged
Two type of surfactant :--
Anionic surfactant:---The hydrophobic part is an anion for example Rcoo- where R is a fluorine containing hydrophobic
In solution, the head is negatively charged. This is the most widely used type of surfactant for laundering, dishwashing liquids and shampoos because of its excellent cleaning properties and high sudsing potential. The surfactant is particularly good at keeping the dirt away from fabrics, and removing residues of fabric softener from fabrics.
Anionic surfactants are particularly effective at oily soil cleaning and oil/clay soil suspension. Still, they can react in the wash water with the positively charged water hardness ions (calcium and magnesium), which can lead to partial deactivation. The more calcium and magnesium molecules in the water, the more the anionic surfactant system suffers from deactivation. To prevent this, the anionic surfactants need help from other ingredients such as builders (Ca/Mg sequestrants) and more detergent should be dosed in hard water.
The most commonly used anionic surfactants are alkyl sulphates, alkyl ethoxylate sulphates and soaps.
In laundry detergents, cationic surfactants (positive charge) improve the packing of anionic surfactant molecules (negative charge) at the stain/water interface. This helps to reduce the dirtl/water interfacial tension in a very efficient way, leading to a more robust dirt removal system. They are especially efficient at removing greasy stains.
An example of a cationic surfactant used in this category is the mono alkyl quaternary system
The termsurfactantis ablendofsurfaceactiveagent. Surfactants are usuallyorganic compoundsthat areamphiphilic, meaning they contain bothhydrophobicgroups (their "tails") andhydrophilicgroups (their "heads"). Therefore, they are soluble in both organic solvents and water. The term surfactant was coined by Antara products in 1950.InIndex Medicusand theUnited States National Library of Medicine, "surfactant" is reserved for the meaningpulmonary surfactant. For the more general meaning, "surface active agent" is the heading.
Amicelle—thelipophilictails of the surfactant molecules remain on the inside of the micelle due to unfavourable interactions. The polar "heads" of the micelle, due to favourable interactions with water, form ahydrophilicouter layer that in effect protects the hydrophobic core of the micelle. The compounds that make up a micelle are typically amphiphilic in nature, meaning that not only are micelles soluble in protic solvents such as water but also in aprotic solvents as a reverse micelle
Surfactants reduce the surface tension of water byadsorbingat the liquid-gas interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. Many surfactants can also assemble in the bulksolutionintoaggregates. Examples of such aggregates are vesiclesandmicelles. The concentration at which surfactants begin to formmicellesis known as thecritical micelle concentrationor CMC. When micelles form in water, their tails form a core that can encapsulate an oil droplet, and their (ionic/polar) heads form an outer shell that maintains favourable contact with water. When surfactants assemble in oil, the aggregate is referred to as a reverse micelle. In a reverse micelle, the heads are in the core and the tails maintain favourable contact with oil. Surfactants are also often classified into four primary groups; anionic, cationic, non-ionic, and zwitterionic(dual charge)
Thermodynamicsof the surfactant systems are of great importance, theoretically and practically. This is because surfactant systems represent systems between ordered and disordered states of matter. Surfactant solutions may contain an ordered phase (micelles) and a disordered phase (free surfactant molecules and/orionsin the solution).Ordinary washing up (dishwashing)detergent, for example, will promote water penetration in soil, but the effect would only last a few days (many standard laundry detergent powders contain levels of chemicals such assodiumandboron, which can be damaging to plants and should not be applied to soils). Commercial soil wetting agents will continue to work for a considerable period, but they will eventually be degraded by soil micro-organisms. Some can, however, interfere with the life-cycles of some aquatic organisms, so care should be taken to prevent run-off of these products into streams, and excess product should not be washed down.
Applications and sources
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Surfactants play an important role in many practical applications and products, including:
- Fabric softener
- Soil remediation
- Ski wax, snowboard wax
- Deinkingofrecycled paper, both in flotation, washing and enzymatic processes
- Foaming agents
- Agrochemical formulations
- Quantum dotcoating
- Hair conditioners(after shampoo)
- Fire fighting
- Pipeline, Liquid drag reducing agent
- Alkali Surfactant Polymers (used to mobilize oil inoil wells)
- Ferro fluids
Pulmonary surfactantsare also naturally secreted by type II cells of the lungalveoliinmammals.
A surfactant can be classified by the presence of formally charged groups in its head. A non-ionic surfactant has no charge groups in its head. The head of an ionic surfactant carries a net 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
Health and environmental controversy
Some surfactants are known to be toxic to animals, ecosystems and humans, and can increase the diffusion of other environmental contaminants.Despite this, they 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. Some surfactants have proposed or voluntary restrictions on their use.
This book will provide an introduction to the nature, properties, and uses of surfactants in the petroleum industry, and will be a companion volume to the Editor's three earlier volumes:
The focus of the new book is on the applications of the principles of colloid and interface science to surfactant applications in the petroleum industry, including attention to practical processes and problems. Books available up to now are either principally theoretical (such as the colloid chemistry texts), very much broader in scope (like Rosen's Surfactants and Interfacial Phenomena, Myers' Surfactant Science and Technology, or Mittal's Solution Chemistry of Surfactants), or else much narrower in scope (like Smith's Surfactant Based Mobility Control).
The applications of surfactants in the petroleum industry area are quite diverse and have a great practical importance. The area contains a number of problems of more fundamental interest as well. Surfactants may be applied to advantage in many parts of the petroleum production process: in reservoirs, in oilwells, in surface processing operations, and in environmental, health, and safety applications. In each case appropriate knowledge and practices determine both the economic and technical successes of the industrial process concerned. In this volume, a wide range of authors' expertise and experiences will be brought together to yield the first surfactant book that focuses on the applications of surfactants in the petroleum industry. Taking advantage of a broad range of authors' expertise allows for a variety of surfactant technology application areas to be highlighted in an authoritative manner. The topics chosen serve to illustrate some of the different methodologies that have been successfully applied.
The book is aimed at scientists and engineers who may encounter or be able to use surfactants, whether in process design, petroleum production, or in the research and development fields. It does not assume a knowledge of colloid chemistry, the initial emphasis being placed on a review of the basic concepts important to understanding surfactants. As such, it is hoped that the book will be of interest to senior undergraduate and graduate students in science and engineering as well since topics such as this are not normally part of university curricula.
The book will provide an introduction to the field in a very applications oriented manner, as the focus of the book is practical rather than theoretical. The first group of chapters (1 to 3) set out fundamental surfactant principles, including chemistry and uses. Subsequent groups of chapters will address industrial practise with Ch. 4-7 aimed at the use of surfactants in improved oil recovery processes, Ch. 8-10 covering oilwell, near-well, and surface uses of surfactants, Ch. 11-13 addressing environmental and safety applications, and the Glossary containing a comprehensive and fully cross- referenced dictionary of terms in the field. A common theme in the chapters will be the use of the fundamental concepts in combination with actual commercial process experiences