Anionic surfactants examples. Surface-active substance

Surface- active substances- compounds that affect the magnitude of surface tension. In the process of interaction of liquid molecules, cohesive forces are formed between them. This force will be different in the surface and inner (deep) layers. Considering the state of the liquid, it is easy to establish that the particles that are directed into the system, with different parties surrounded by the same molecules that affect them. The resultant of all forces that act on such a molecule is zero. Therefore, liquids have the smallest surface area for a given volume. This is clearly manifested in the spherical shape of the droplets. The presence of impurities of various compounds in liquids determines the magnitude of surface tension.

Nanomaterials for biological applications

The dissertation is especially suitable for students who are interested in using modern quantum chemical approaches and who make sense chemical reactions. Given that this is a complex topic, the specific content of the work can only be determined based on an assessment of the applicant's ability. Sutherland and others. Nanostructured materials are unique due to their specific physicochemical properties, which are also reflected in specific interactions with living organisms, which makes nanomaterials unique biological properties.

The structure of surfactant molecules

Particles fatty acids and alcohols consist of two parts that have different properties, so these compounds are very often called amphiphilic structures. One part of the molecule is represented by a hydrocarbon chain, and the other by various functional groups (amino group, hydroxyl, carboxyl, sulfo group). The longer the hydrocarbon chain, the stronger the particles will be expressed, the weaker they will interact with water.

The useful properties of nanomaterials with biological properties are wide and can be used, for example, in medicine for the treatment or diagnosis of diseases, biologically active nanomaterials can be used for industrial or environmental purposes to remove unwanted biological, especially microbial, contaminants. Typical examples are silver nanoparticles, which exhibit high antimicrobial activity, which can be used to treat microbial infections, including those caused by highly resistant bacterial strains that cannot be treated with classical antibiotics.

Surfactants of organic origin: proteins, soaps, alcohols, ketones, aldehydes, tannins, ketones, etc. Surface-inactive substances do not affect surface tension(starch, glucose, fructose).

Nonionic surfactants (NSA) are high molecular weight biocompounds that do not form ions in water. These substances enter the reservoirs together with industrial (chemical, textile, household (use of various household) effluents, as well as with waste from agricultural land (herbicides, fungicides, insecticides, as well as folios as emulsifiers).

On the other hand, it is necessary to take into account the possible undesirable biological effects of nanomaterials when interacting with biological systems, which may arise due to their unique and unusual biological properties. Study of the mechanism of interaction of nanomaterials with biological systems at different cellular levels and their use for biological and medical use represents a very interesting and diverse area of scientific research.

Nanomaterials for catalytic applications

Due to their specific physicochemical properties, noble metal nanoparticles exhibit high chemical activity, namely high catalytic activity. Catalytic effects can be attributed to the chemical nature of the metals themselves and, moreover, they can be increased by the nanosize and morphology of the particles of these metals, which leads to a significant increase in the surface area of the metal required for efficient heterogeneous catalysis. In the field of catalytic applications, research and development can be focused, in particular, on the synthesis and development of highly catalytically effective nanomaterials based on metals and their compounds, applicable, for example, for environmental technologies or industrial chemistry in a number of chemical processes or in the field of energy technology.

Surfactants: harm and benefit

The surface tension has great value for intestinal absorption. For example, fats, as well as lipids, enter the alimentary tract in the form of droplets. The latter are emulsified in the small intestine with the help of bile acids. Only after that these fats are hydrolyzed by lipolytic enzymes. Soaps (surfactants) are often added to insecticides to increase effectiveness. The manipulation allows insecticides to better interact with the surface of the body of insects. However, surfactants have not only positive, but also negative effects on the body. For example, shampoo contains very harmful foaming agents (surfactants), such as sodium and ammonium lauryl sulfate, ammonium and sodium laureth sulfate. There is an opinion that these components have a carcinogenic effect.

However practical use nanomaterials is often accompanied by aggregative instability of metal nanoparticles or limited possibility of separation after the reaction in real applied systems. One way to prevent these undesirable phenomena is to fix metal nanoparticles on selected inert substrates. Examples are natural aluminosilicate materials, metal oxides, or magnetic materials such as iron oxides, which further facilitate the magnetic separation of the catalyst after the reaction.

Surfactants (surfactant) - chemical compounds, which, concentrating on the interface, cause a decrease in surface tension .

The main quantitative characteristic of surfactants is surface activity- the ability of a substance to reduce surface tension at the phase boundary is the derivative of surface tension with respect to surfactant concentration as C tends to zero. However, surfactants have a solubility limit (the so-called critical micelle concentration or CMC), with the achievement of which, when a surfactant is added to a solution, the concentration at the phase boundary remains constant, but at the same time, self-organization of surfactant molecules in a bulk solution (micelle formation or aggregation) occurs. As a result of this aggregation, so-called micelles are formed. hallmark micelle formation is the turbidity of the surfactant solution. Aqueous solutions Surfactants, during micelle formation, also acquire a bluish tint (gelatinous tint) due to the refraction of light by micelles.

Obtaining nanoparticles and nanocomposites for catalytic or spectroscopic applications

Current developments in nanotechnology are moving from the preparation and use of isolated nanoparticles to systems in which they are firmly trapped on suitable basis. Such composites have unique physicochemical properties that differ from the nanoparticles themselves. In addition to the increased aggregate stability of nanoparticles, the synergistic effect of the physicochemical properties of these materials is often synergistic.

The aim of this work will be research and development in the preparation, characterization and application of noble metal nanoparticles or their compounds. The area of research will focus on the development and optimization of methods for obtaining nanoparticles and nanocomposites based on these metals and, possibly, their compounds, including their characteristics. These materials will then be studied and tested for their performance in heterogeneous catalysis or spectroscopic applications.

Methods for determining CMC:

Surface tension method
Method for measuring the contact angle with TV. or liquid surface(contact angle)
Spindrop/Spinning drop method

Surfactant structure

Surfactant classification

Ionic surfactants
- Cationic surfactants
- Anionic surfactants
Nonionic surfactants
- Alkyl polyglucosides
- Alkylpolyethoxylates

The impact of surfactants on the environment

Surfactants are divided into those that are rapidly destroyed in environment and those that are not destroyed and can accumulate in organisms in unacceptable concentrations. One of the main negative effects of surfactants in the environment is a decrease in surface tension. For example, in the ocean, a change in surface tension leads to a decrease in the retention of CO 2 in a body of water. Only a few surfactants are considered safe (alkylpolyglucosides), since their degradation products are carbohydrates. However, when surfactants are adsorbed on the surface of earth/sand particles, the degree/rate of their degradation decreases many times over. Since almost all surfactants used in industry and household, have positive adsorption on particles of earth, sand, clay, under normal conditions they can release (desorb) heavy metal ions held by these particles, and thereby increase the risk of these substances entering the human body.

Another important application of these materials is their use in advanced oxidation processes used for remediation technologies used for cleaning Wastewater and the old ecological burden. A common and recurring requirement applied by industry is their ability to degrade toxic and often persistent organic pollutants that counter or directly decontaminate the traditionally used biological class that is an integral part of most wastewater treatment plants.

Surfactants in the oceans

According to some reports, surfactants, adsorbed on the surface of water in reservoirs, increase the absorption of radar signal waves. In other words, radars and satellites are worse at capturing the signal from underwater objects in water bodies with a certain concentration of surfactants.

Areas of use

Detergents. The main use of surfactants is as an active component of detergents and cleaning products, soap, for the care of premises, dishes, clothes, things, cars, etc. In 2007, more than 1 million tons of synthetic detergents, mainly - washing powders.
Cosmetics. The main use of surfactants in cosmetics is shampoos, where the content of surfactants can reach tens of percent of the total volume. Surfactants are also used in small amounts in toothpaste, lotions, tonics, and other products.
Textile industry. Surfactants are mainly used to remove static electricity on the fibers of synthetic fabric.
leather industry. Protection leather goods from light damage and sticking.
Paint industry. Surfactants are used to reduce surface tension, which ensures that the paint material easily penetrates into small depressions on the surface to be treated and fills them while displacing another substance (for example, water) from there.
Paper industry. Surfactants are used to separate ink and boiled pulp in the recycling of used paper. Surfactant molecules are adsorbed on the ink pigment. The pigment becomes hydrophobic. Next, the air is passed through a solution of pigment and cellulose. Air bubbles are adsorbed on the hydrophobic part of the surfactant and particles of the ink pigment float to the surface. See flotation.
Metallurgy. Surfactant emulsions are used to lubricate rolling mills. Reduce friction. Withstand high temperatures at which the oil burns.
Plant protection. Surfactants are widely used in agronomy and agriculture to form emulsions. They are used to increase the efficiency of transporting nutrients to plants through membrane walls.
Food industry. The surfactant is used in ice cream, chocolate, whipped cream and dressings for salads and other dishes.
Oil production. Surfactants are used to hydrophobize the bottomhole formation zone (BFZ) in order to increase oil recovery.

Surface-enhancing Raman spectroscopy is one of the modern analytical methods for detecting very low concentrations of substances. The continued development of Raman spectrometers means that these instruments are becoming more cost-effective, and therefore the number of these devices is expanding not only in scientific workplaces, but, in particular, they are becoming a regular part of commercial laboratories. A very important area where these devices can be found, whether in the form of classic or mobile versions, is the individual components of the police, fire brigade or army, where these tools are used to identify flammable substances, drugs, explosives, etc. because the surface is enhanced Raman spectroscopy has a very significant potential for future expansion in many areas human activity, and the goal of this problem is to create reproducible, efficient, reliable and easy-to-use substrates based on silver and gold.

See what "Surfactant" is in other dictionaries:

SURFACE-ACTIVE SUBSTANCE, a substance that lowers the SURFACE TENSION of the SOLVENT in which it is dissolved. In water, for example, DETERGENTS and SOAPs act as surfactants. Their molecules focus on... ... Scientific and technical encyclopedic dictionary

Study of the formation of nanoparticles and their complexes organized on the surface or in the bulk of the solid phase. Current developments in nanotechnology are directed towards the preparation and use of isolated nanoparticles into more complex systems of organized arrays of nanoparticles firmly embedded on solid surfaces, both macroscopic and microscopic. Such systems have unique physicochemical properties that are not observed in isolated nanoparticles. In addition to increased aggregate stability and chemical resistance of nanoparticles, such synergistic effects often result in the sum of the positive properties of the combined systems.

surface-active substance- Surfactant Substance capable of being adsorbed on the phase interface with a corresponding decrease in their surface tension. Note As part of magnetic suspensions, corrosion inhibitors, defoamers, stabilizers, wetting agents and others are used ...

Nanoparticles attached to the surface of a solid phase usually affect its physicochemical properties, and, conversely, the presence of the solid phase on which they are embedded significantly affects the nanoparticles themselves. The basic principle is to divide the methods for preparing such arrays into two main areas, according to the scale of the solid phase with which the nanoparticles are combined. In the case of macroscopic objects on a scale of 10-3 m and above, the principle is the formation of surface films containing nanoparticles, respectively. about the inclusion of nanoparticles directly into the bulk of the solid phase.

surface-active substance- 3.19 surfactant: Mineral or organic additives introduced into the mixture to increase the adhesion of the binder to the surface of the stone material or to control the processes of formation in the mixture. A source … Dictionary-reference book of terms of normative and technical documentation

Many physico-chemical methods are used to create surface films, in particular spin coating, spin coating, and Langmuir-Blodgett films. To incorporate the nanoparticles into the bulk of the solid phase, a solid phase synthesis method can be used in a system containing the appropriate nanoparticles, or the nanoparticles can be mechanically mixed into the bulk of the existing solid phase. In the case of solid-phase microscopic sizes, methods based on the adsorption of nanoparticles on the surface of the solid phase are most often used either directly or with the help of suitable modifiers.

Surfactant term English term surfactant Surfactant synonyms Abbreviations Associated terms amphoteric surfactant, hydrophobic interaction, dispersion, colloid chemistry, critical micelle concentration,… … encyclopedic Dictionary nanotechnology

surface-active substance- aktyvioji paviršiaus medžiaga statusas T sritis Standartizacija ir metrologija apibrėžtis Medžiaga, kuri įterpta į skysčio ar kietojo kūno paviršių sumažina to paviršiaus įtemptį. atitikmenys: engl. surface active substance; surfactant vok.… … Penkiakalbis aiskinamasis metrologijos terminų žodynas

Nanoparticles can be added to a solid phase microparticle system only after previous preparation in another system or directly synthesized in the presence of solid phase microparticles. Composite materials, as already mentioned, often have significantly different physical and chemical properties compared to the original systems. Typically, there are changes in surface energy, surface bioactivity, catalytic activity of the systems involved, or changes in optical properties.

These new properties can be used in a wide variety of applications such as very poor wetting or very wetting surfaces, changing surface interactions with living systems, and changing the catalytic activity of the original systems.

surface-active substance- paviršinio aktyvumo medžiaga statusas T sritis chemija apibrėžtis Medžiaga, kuri adsorbuojasi fazių sąlytyje ir sumažina paviršiaus įtemptį. santrumpa(os) PAM atitikmenys: engl. surface active substance; surfactant superficially active ... ... Chemijos terminų aiskinamasis žodynas

surface-active substance- aktyvioji paviršiaus medžiaga statusas T sritis fizika atitikmenys: engl. surface active substance; surfactant vok. grenzflächenaktiver Stoff, m; oberflächenaktiver Stoff, m; Tensid, n rus. surfactant, n pranc. agent tensio… … Fizikos terminų žodynas

Phase transitions and the possibility of their influence on nanotechnology

Phase transitions between the physical states of pure substances are uniquely determined by the temperature and pressure of the environment with which the system is studied in equilibrium. However, the word balance plays a very important role here. important role, since if the studied system is not in balance, there is no phase transition under equilibrium conditions, and the system can exist for some time in a different state than under equilibrium conditions. However, a similar situation can be achieved by mixing the original pure substance with another substance, and the resulting mixture then behaves differently from the original pure state in terms of his prior art.

A substance capable of being adsorbed on a phase interface (eg, liquid and gas) and lowering its surface tension; P. a. in. are used, for example, as detergents, in the preparation of aqueous dispersions ... Big Medical Dictionary

low foaming surfactant- — Topics oil and gas industry EN low foaming surfactant … Technical Translator's Handbook

However, the transition between the states of the state is governed by very complex laws in real world related to the question of creating a new stage. The appearance of a new phase in the volume of the original phase requires some work necessary to create a phase interface - homogeneous nucleation. This work is related to the aforementioned deflection of the system from equilibrium. However, the presence of heterogeneous impurities in the initial phase can significantly reduce this work in order to create a new phase interface in situations where the emerging phase wets the surface of the heterogeneous impurity.

See Antiatelectic Factor... Big Medical Dictionary