Four types of surfactant - characteristic features! Introduction

And road surfaces for stone, concrete, brick, wood. With delivery throughout Russia!

Surface active substances (surfactants) - chemical compounds, which, concentrating on the interface, cause a decrease in surface tension.

The first and most popular surfactant, which for many thousands of years, is soap. And annually, despite the competition of new detergents and cleaning products, first on the basis of alkyl benzene sulfonate, and now others, more than 9 million tons of soap is consumed in the world. That soap remains the most common in the world of surfactants.

Thanks to detergent, wetting, emulsifying, dispersing and other valuable properties, surfactants are widely used in the production of detergents and cleaning products, cosmetics and pharmaceuticals. And also for the production of latex, rubber, polymers, in the extraction, transportation and processing of oil, etc.

Pauls are chemical cleaning, detergents, as well as plant protection products, textiles, leather and paper, building materials, corrosion inhibitors. A large part of surfactants (about 60%) is accounted for by the production of detergents (SMS - synthetic detergents).

The main raw materials for the production of surfactants are the products of oil refining and petrochemical synthesis: low molecular weight and higher paraffins, olefins, synthetic fatty acids, higher fatty alcohols, alkyl derivatives of benzene and phenol, etc.

Synthetic surfactants (surfactants) are divided into 4 classes:

anionic surfactant - compounds that dissociate in aqueous solutions with the formation of anions, causing surface activity. Among them, alkyl benzene sulfonate, fatty acid sulfate sulfate esters are the most important;

cationic surfactants - compounds that dissociate in aqueous solution with the formation of cations that determine surface activity. Among cationic surfactants, quaternary ammonium compounds, imidazalines, fatty amines are most important.

amphoteric (ampholytic) surfactants - compounds that, in aqueous solutions, depending on the pH value of the medium, ionize differently and act - they display the properties of cationic surfactants in an acidic solution, and anionic surfactants in an alkaline solution. The main amphoteric surfactants are alkyl betaines, alkylaminocarboxylic acids, alkyl imidazolines derivatives, alkylaminoalkanesulfonates.
nonionic surfactants - compounds that are fully consistent with the name, dissolve in water without ionizing. The solubility of nonionic surfactants in water is due to the presence of functional groups. As a rule, they form nitrates in aqueous solution due to the appearance of hydrogen bonds between water molecules and oxygen atoms of the polyethylene glycol part of the surfactant molecule. Non-ionic surfactants include: polyglycolic esters of fatty alcohols and acids, polyglycolic esters of fatty amides, acylated or alkylated polyglycolic esters of alkylamides.

Synthetic detergents

The main types of surfactants used in the composition of CMC are alkylbenzene sulfonates with a linear alkyl chain (LABS) and C12-C15 alcohol derivatives (ethoxylates, sulfates, alcohol ethoxy sulfates). LABS and alcohol sulfates, along with soap, refer to anionic surfactant, alcohol ethoxylates - to non-ionic surfactants.
The second important type of surfactant for SMS is nonionic surfactants, obtained by oxyethylation of higher fatty alcohols or alkylphenols.
Nonionic surfactants, as a rule, are superior to anionic surfactants both in cleaning and degreasing action and emulsify more or less oil and fat depending on the use profile. Also, nonionic surfactants, due to the variability of their bases and degree of ethoxylation or propoxylation, can ideally be tailored to a specific task.
The most commonly used non-ionic surfactants are fatty alcohol oxyethylates. Ethoxylates based on long chain alcohols (C12-C15), due to their better detergency, are more commonly used in CMC laundry recipes, it is preferable to use ethoxylates based on short chain alcohols (C9-C11) for cleaning solid surfaces. These ethoxylate are distinguished by better wetting ability and wetting angle with respect to hard surfaces.

Cosmetics

Surfactant widely used in cosmetics. “These are shampoo, liquid soap, rinses, hair dye and hair conditioners after washing. Pava is a cosmetic cream for the face, body, hands, including therapeutic and prophylactic action.

Anionic substances (alkyl sulphates and alkyl ether sulphates) are used as the main surfactants, which provide a sufficient washing effect and foaming with a sparing effect on the skin and hair.

Alkylolamides, glycol ethers of fatty alcohols are used as solubilizers for the introduction of dusts and other hydrophobic components (oils, biologically active substances).

Cationic, non-ionic surfactants, beta-yins are used as conditioning agents, removing the charges of static electricity and facilitating combing of dry and damp hair.

Amphoteric surfactants in combination with anionic surfactants improve foaming ability and increase the safety of formulations, and when combined with cationic polymers, they enhance the positive effect of silicones and polymers on hair and skin. These derivatives are derived from natural raw materials, so they are quite expensive components. The most commonly used derivatives of betaine (cocamopropyl betaine)

Most effective antistatic agents are cationic surfactants - quaternary ammonium compounds, although there are incompatibility problems with anionic surfactants. However, in a mixture with non-ionic and amphoteric substances, we manage to achieve the desired effect and preserve the stability of the finished product.

Federal Agency for Science and Education

State educational institution

higher vocational education

Kazan State Technological University

Nizhnekamsk Institute of Chemical Technology

Department of Chemistry

Specialty 240401

« Colloidal surfactants»

Completed: Zaripov Z. I. gr.1806

Checked: Nurieva E.N.

Nizhnekamsk 2011

Introduction …………………………………………………………………………… 3

Classification of surfactants by polar groups ……………………………… .4

Anionic surfactants ……………………………………………………………… .6

Non-ionic surfactants ……………………………………………………………… 13

Cationic Surfactants …………………………………………………………… ... 18

Zwitter - ionic surfactants …………………………………………………… ... 22

SAS adsorption at interphase boundaries ……………………………………… .25

Natural surfactants ………………………………………………………………… ..26

Dermatological effect of surfactants ………………………………………… 27

The impact of surfactants on the environment ………………………………… 30

Biodegradability ………………………………………………………………… 31

Surfactant marking …………………………………………………………… 32

Environmental protection ……………………………………………… ... 33

Domestic use ……………………………………………………………… ..33

Bibliographic list ……………………………………………………… 34

Introduction

Surface-active substances, substances that can accumulate (thicken) on the contact surface of two bodies, called the interface, or the interfacial surface. On the interfacial surfactant surface. form a layer of increased concentration - the adsorption layer. Any substance in the form of a component of a liquid solution or gas (vapor) under appropriate conditions can show surface activity, i.e., be adsorbed under the action of intermolecular forces on a particular surface, reducing its free energy. However, only those substances are usually referred to as surface-active substances, the adsorption of which from solutions already at very low concentrations (tenths and hundredths of a%) leads to a sharp decrease in the surface tension.

Typical surfactants are organic compounds of diphilic structure, that is, containing atomic groups in a molecule, which differ greatly in the intensity of interaction with the environment (in the most practically important case, water). So, in the surfactant molecules there is one or several hydrocarbon radicals that make up the oleo or lipophilic part (it’s also the hydrophobic part of the molecule), and one or more polar groups, the hydrophilic part. Oleophilic (hydrophobic) groups weakly interacting with water determine the tendency of a molecule to transition from an aqueous (polar) medium to a hydrocarbon (nonpolar) medium. Hydrophilic groups, on the contrary, keep the molecule in a polar medium or, if the surfactant molecule is in a hydrocarbon fluid, determine its desire to transition to a polar medium. Thus, the surface activity of surfactants dissolved in non-polar liquids is caused by hydrophilic groups, and dissolved in water by hydrophobic radicals.

The classification of the pav in the polar groups

The first classification of surfactants is based on the charge of the polar group. It is generally accepted to divide surfactants into anionic, cationic, non-ionic, and zwitterionic. The surfactant molecules in the last group, under normal conditions, contain both charges: anionic and cationic. In the literature, they are often referred to as “amphoteric” surfactants, but this term is not always correct and should not be used as a synonym for the term “zwitterionic” surfactant. Amphoteric surfactant is a substance that, depending on the pH of the solution, can be cationic, zwitterionic or anionic. A prime example of amphoteric organic substances is simple amino acids. Most of the so-called zwitterionic surfactants have similar properties. However, some zwitterionic surfactants retain one of the charges in a wide pH range, for example, compounds that include the cationic quaternary ammonium group. Thus, a surfactant containing carboxylate and quaternary ammonium groups will be zwitterionic up to very low pH values, but will not be amphoteric.

Most ionic surfactants are monovalent, but there are also important representatives of bivalent anionic surfactants. The physico-chemical properties of ionic surfactants are influenced by the nature of the counterion. In most cases, the anionic surfactant acts as a counter-ion sodium ion, while other cations, such as lithium ions, potassium, calcium or protonated amines, are used as such only for special purposes. Counterions for cationic surfactants are usually halide ions or methyl sulfate ions.

Hydrophobic surfactant groups are usually represented by hydrocarbon radicals, as well as polydimethylsiloxane or fluorocarbon groups. Surfactants of the latter two types are particularly effective in non-aqueous media.

For a small number of surfactants, there is some uncertainty in the classification. For example, surfactants containing amine oxides are sometimes referred to as zwitterionic, sometimes as cationic, and even as non-ionic surfactants. The charge of molecules of these substances depends on the pH of the aqueous phase; it can be considered that in the neutral state they carry anionic and cationic charges or are non-ionic dipole molecules. Ethoxylated fatty amines containing the nitrogen atom of the amino group and the polyoxyethylene chain may be included in the class of cationic or non-ionic surfactants. The non-ionic character of such surfactants prevails in the case of very long polyoxyethylene chains, while with short or medium length polyoxyethylene chains, the physicochemical properties usually correspond to cationic surfactants. Surfactants containing an anionic group in the molecule, such as the sulphate, phosphate or carboxylate, and polyoxyethylene chains, are also quite common. Such surfactants, such as sulfoesters and others, usually contain short polyoxyethylene chains, and therefore are always considered as anionic surfactants.

Hello, dear visitor of our site!

In the language of chemists, surface-active substances (surfactants) are chemical compounds that can adsorb at the interface, one of which is usually water, and reduce the surface tension ...

All surfactants are divided into four main classes: anionic, cationic, non-ionic and ampholytic:

Anionic surfactants are compounds that dissociate in aqueous solutions to form anions (negatively charged ions) that cause surface activity. They have good sanitary and hygienic properties and are well combined with other surfactants.

Cationic surfactants are compounds that dissociate in an aqueous solution to form cations that determine surface activity, they have valuable properties - bactericidal.

Nonionic surfactants are compounds that dissolve in water without being ionized. Non-ionic surfactants are less sensitive to salts that cause water hardness than anion-active and cationic surfactants.

Ampholytic surfactants are widely used in the manufacture of foam detergents and shampoos, due to their mild effect on the skin. Depending on the pH value, they exhibit the properties of cation-active or anion-active surfactants.

Thanks to detergent, wetting, emulsifying, dispersing and other valuable properties, surfactants are widely used in the production of detergents and cleaning products, cosmetics and pharmaceuticals. latex, rubber. polymers, chemical plant protection products, textiles, leather and paper, building materials, corrosion inhibitors, in the extraction, transportation and processing of oil, etc. Most surfactants are used for the production of synthetic detergents (SMS).

Today, everyone shouts at the top of his voice about the dangers of surfactants, but no one really tells what is particularly harmful, and why ...

We will try to consider the surfactants used in the production of laundry detergents. Their positive and negative sides.

In the production of laundry detergents, anionic and nonionic surfactants are mainly used. Compared with anionic surfactants, nonionic surfactants have the ability to adsorb on tissue in smaller quantities. But again, it cannot be said that anionic surfactants are worse than non-ionic. There are many types of nonionic surfactants and anionic surfactants.

One of the main criteria for environmental safety and the impact on the human body is the biodegradability of surfactants. Distinguish between primary and complete biodegradability. Under primary, they mean structural changes (transformation) of surfactants by microorganisms, leading to a loss of surface-active properties, under full biodegradability — meaning the final biodegradation of surfactant to carbon dioxide and water. Simply speaking, the primary is washed out completely and full - when completely decomposed when released into the water area. The best surfactant - which has 100% primary and full biodegradability. Indicators of biodegradability of the main classes of surfactants are shown in the table:

Table 1. Indicators of biodegradation of the main classes of surfactants that are part of household chemicals:

Surfactant name	Primary biodegradation. OECD screening test (%)	Full biodegradation
Surfactant name	Primary biodegradation. OECD screening test (%)	test in a closed bottle (%)	modified screening test in (%)
Anionic surfactants
Linear alkyl benzene sulfonate	95	65	73
C14 – C18 a-Olefin Sulfonates	99	85	85
C16 – C18 Sulphates of fatty alcohols	99	91	80
C12 – C15 Sulfates alcohol ethoxylates	99	86	-
C16 – C18 Methyl esters of sulfonated fatty acids	99	76	-
Nonionic surfactants
C16 – C18 Fatty alcohols 14 EO	99	86	80
C12 – C14 Fatty alcohols 30 EO	99	27	-
C12 – C14 Fatty alcohols 50 EO	98	-	-
C12 – C18 Fatty alcohols 6 EO 2 software	98	83	68
C12 – C18 Fatty alcohols 5 EO 8 software	70	15	-
C12 – C14 Fatty alcohols 10 software	50-63	21	11
C13-C15 Oxoids 7 EO	93	62	-
i-Nonylphenols 9 EO	6-78	5-10	8-17
n – С8 – С10 Alkylphenols 9 EO	84	29	-
C12 – C18 Amines 12 EO	88	33	-
EO / PO block polymers	32	0-10	18
Alkylpolyglycosides	-	71-73	72-80

As we can see, the table shows the main surfactants used in the production of detergents.

So from the table it follows that the primary biodegradability of anionic and non-ionic surfactants is almost the same, and the full one depends on the surfactant formula. That is, when choosing a surfactant, in the production of household chemicals, you can choose the best option for anionic and non-ionic surfactants, which will behave in the same way as part of SMS.

The composition of the detergent composition, the concentration of the cleaning solution, its initial temperature, the duration of the contact of the fabric with the solution, the amount of wash water significantly affect the formation of residual amounts of surfactants on the fabrics of linen and clothes. Therefore, the introduction of non-ionic surfactants into the compositions reduces the degree of adsorption of anionic surfactants on tissues by 2–3 times. That is, it is safe to say that the surfactant complex (anionic and non-ionic) is much more efficient than using a single surfactant, both for washing and for safety.

Surfactants have relatively low toxicity to humans and animals. According to the degree of increase in the toxicity of surfactants can be distributed in the following order: non-ionic, anion-active, cation-active. When exposed to the skin and mucous membranes, synthetic surfactants can be irritating and resorptive. It has been established that compositions from anionic and non-ionic compounds have a less pronounced biological and toxic effect. Non-ionic surfactants reduce the adsorption of anionic substances and only in large doses can have a damaging effect on the skin. The greatest danger of surfactants and preparations based on them for people is their sensitizing effect, the ability to cause allergic reactions. Sensitization can occur in any way the surfactant enters the body.

As you can see, the use of anionic or non-ionic surfactants alone does not guarantee product quality and safety. The best result is the use of anionic and non-ionic high-quality surfactants with the highest biodegradability in the production of the complex.

for several orders of magnitude higher than in the volume of liquid, so even with negligible content in water (0.01-0.1% by weight), surfactants can reduce surface tension water border with air from 72.8 · 10 -3 to 25 · 10 -3 J / m 2, i.e. almost tosurface tension hydrocarbon fluids. A similar phenomenon occurs at the boundary of the aqueous solution of surfactant - hydrocarbon liquid, which creates the prerequisites for the formation of emulsions.

The main quantitative characteristic of a surfactant is - the ability of a substance to reduce surface tension at the interface, this is the derivative of the surface tension with respect to the surfactant concentration as C tends to zero.

In the volume of the liquid phase surfactant may be
- or as individual molecules (truly soluble surfactants),
—or uniting into groups of several dozen molecules — The ultimate concentration of surfactant in a solution at which the formation of micelles begins is called).

Surfactant structure

As a rule, surfactants are organic compounds having amphiphilic structure, that is, their molecules have in their composition the polar part, the hydrophilic component (functional groups -OH, -COOH, -SOOOH, -O-, etc., or, more often, their salts -OH, -COONa, -SOOONa and etc.) and non-polar (hydrocarbon) part, a hydrophobic component. An example of a surfactant is ordinary soap (a mixture of sodium salts of fatty carboxylic acids — oleate, sodium stearate, etc.) and SMS(synthetic detergents), as well as alcohols, carboxylic acid, amines, etc.

Surfactant classification

Ionogenic surfactants
- Cationic Surfactants
- Anionic Surfactants
- Amphoteric

Nonionic surfactants
- Alkylpolyglucosides
- Alkyl polyethoxylates

Anionic surfactants
- contain in the molecule one or several polar groups and dissociate in aqueous solution with the formation of long-chain anions, determining their surface activity. These are groups: COOH (M), OSO 2 OH (M), SO 3 H (M), where M is a metal (single, double or trivalent). The hydrophobic part of the molecule is usually represented by limit or unsaturated aliphatic chains or alkyl aromatic radicals.

In anionic surfactants cation m. not only metal, but also an organic base. Often it is di- or triethanolamine. Surface activity begins to occur when the length of the hydrocarbon hydrophobic chain C 8 and with increasing chain length increases up to the complete loss of solubility of surfactants in water. Depending on the structure of the intermediate functional groups and the hydrophilicity of the polar part of the molecule, the length of the hydrocarbon part can reach C 18 .

Cationic Surfactants
- dissociate in aqueous solution with the formation of a surface-active cation with a long hydrophobic chain and an anion (usually a halide, sometimes an anion of sulfuric or phosphoric acid).

Among the cationic surfactants, nitrogen-containing compounds predominate; Nitrogen-free substances are also used: sulfonium + X- and sulfoxonium + X-, phosphonium + X-, arsonium + X-, iodonium compounds.

Cationic surfactants reduce surface tension less than anion-active, but they chemically interact with the surface of the adsorbent, for example. with cellular proteins of bacteria, causing a bactericidal effect.

Ampholytic surfactants
- depending on the pH value, they exhibit the properties of cation-active or anion-active surfactants.

The molecule contains a hydrophilic radical and a hydrophobic part capable of being an acceptor or proton donor, depending on the pH of the solution. Typically, these surfactants include one or more basic and acidic groups, and may also contain a non-ionic polyglycolic group. At some pH values, called isoelectric point, surfactants exist in the form of zwitter-ions. The ionization constants of acidic and basic groups of truly soluble amphoteric surfactants are very low, however, cation-oriented and anion-oriented zwitterion are most common. The primary, secondary or tertiary ammonium group, pyridine residue or imidazoline residue is usually used as a cationic group. Instead of N m. S, P, As atoms, etc. The anionic groups are carboxyl, sulphonate, sulfoester or phosphate groups.

Nonionic PA
- high-molecular compounds that do not form ions in aqueous solution.

Their solubility is due to the presence of hydrophilic ether and hydroxyl groups in the molecules, most often the polyethylene glycol chain. When dissolved, hydrates are formed due to the formation of a hydrogen bond between the oxygen atoms of the polyethylene glycol residue and water molecules. Due to the breaking of the hydrogen bond with increasing temperature, the solubility of non-ionic surfactants decreases, so for them the cloud point is the top. The temperature limit of micellization is an important indicator. Many compounds containing a mobile H atom (acids, alcohols, phenols, amines), reacting with ethylene oxide, form non-ionic surfactants RO (C2H4O) nH. The polarity of one oxyethylene group is significantly less than the polarity of any acid group in anion-active surfactants. Therefore, from 7 to 50 oxyethylene groups are required to impart the required hydrophilicity to the molecule and the HLB value depending on the hydrophobic radical. A characteristic feature of non-ionic surfactants is a liquid state and low foaming in aqueous solutions.

Non-ionic surfactants combine well with other surfactants and are often included in formulations.

Thanks to detergent, wetting, emulsifying, dispersing and other valuable properties, surfactants are widely used in the production of detergents and cleaning products, cosmetics and pharmaceuticals. latex, rubber. polymers, chemical plant protection products, textiles, leather and paper, building materials, corrosion inhibitors, in the extraction, transportation and processing of oil, etc. Most surfactants are used for the production of synthetic detergents (SMS).

Sources of surfactant in the aquatic environment

Surfactant water bodies come in significant quantities from household (use of synthetic detergents in everyday life) and industrial wastewater (textile, oil, chemical industry, production of synthetic rubbers), as well as from runoff from agricultural lands (included in insecticides, fungicides, herbicides and defoliants as emulsifiers).

The use of surface-active substances (surfactants)

Surfactants are widely used in industry, agriculture, medicine and life. The global production of surfactants is increasing every year, and the share of non-ionic substances in the total output is constantly increasing. All types of surfactants are widely used in the preparation and use of synthetic polymers. The most important area of consumption of micelle-forming surfactants is the production of polymers by emulsion polymerization. The technological and physico-chemical properties of the resulting latexes largely depend on the type and concentration of the surfactants chosen (emulsifiers). Surfactants are also used in suspension polymerization. High molecular weight surfactants are usually used - water-soluble polymers (volivinyl alcohol, cellulose derivatives, vegetable glues, etc.). Mixing varnishes or liquid oil-resin compositions with water in the presence of emulsifiers produces emulsions used in the manufacture of plastics, leather substitutes, nonwovens, impregnated fabrics, waterborne paints, etc. High-molecular water-soluble surfactants, in addition to the use of the above technologically. processes used as flocculants in various types of water treatment. With their help, suspended substances are removed from wastewater and also from drinking water..

Information was borrowed from the following sources:

1) www.wikipedia.org

3) www.hydrodynamictechnology.com

Special attention is paid to surface-active substances when using household chemicals, including washing powders. This is due to many factors, such as biochemical decomposition, toxic indicators, absorption capacity, and the main one is detergency. The essence of this indicator is in how well Pav washs fabric from pollution.
This process can be described as follows: first, the cleaning solution Pav wets dirt on fabric. As a result, around the pollution appears like a penetrating layer of Pav. Through the micro cracks, the Pav penetrates to the places of contact of contamination and tissue, the pollutant, together with the carbon radical Pav, is pulled into the dispersion medium, then the process of grinding of mud particles takes place, separating and stabilizing in the washing solution.
Now we give a description of the main groups Pav:
1. Anionic surfactants (APAS) are organic compounds that, during the formation of an aqueous solution, form an anion with a long carbon radical carrier of surface activity, the cation is surface-active. In other words, when an anionic surfactant gets into the aqueous medium, its molecules are separated into negatively charged anions and positively charged cations. As a result, the negative anions of Pav are connected by positive particles of dirt, transferring them to the solution and thereby separating the dirt from the fabric.
Anionic Pav are used to soften, as detergents, blowing agents. Most effective in alkaline environments.

This is the most common Pav, which is almost 100% biodegradable.
2. Non-ionic surfactants (nonionic surfactants) soluble compounds, both acidic and alkaline, that do not dissociate in water. Possess high washing ability.
Effectively used in soft and hard waters, have a low foaming ability. Biodegradable on average by 85%. In washing powders, the input percentage is very low, 1-2%.
3. Cationic surfactants (CPAS) are organic compounds that, when dissociated in water, form a developed surface-active cation, while the anion is not active. These pavas are used for corrosion inhibitor, as a conditioning agent, as a disinfectant and antibacterial agent.
The adsorption layers of cationic Pav perform antistatic, conditioning functions and have a protective effect on the affected tissue fibers.
4. Amphoteric surfactants - compounds that contain both types of groups in the composition of molecules: acidic (most often carboxyl) and basic (usually the amino group of different degrees of substitution). May exhibit the properties of cationic, nonionic or anionic Pav.
Ampholytic Pav softens fabrics, has an antistatic effect, is effective when used in hard and cold water. Ampholytic Pav are well combined with Pav of all kinds, have good foaming properties, bactericidal activity and dermatological properties.

From our point of view, it is necessary to pay attention to such a widespread Pav as soap of fatty acids, in almost all powders it is found, many manufacturers build their strategy of promotion and promotion of powders exclusively on the PR of this soap.

What you need to pay attention, there are both pluses and minuses. The advantages include: naturalness, mild effects, etc.
The disadvantages include the following: first, the soap, being a salt of a weak organic acid (more precisely, a salt formed by a mixture of three palmitic, margarine and stearic acids) and a strong caustic sodium base, is hydrolyzed in water (i.e., decomposed by it) into acid and alkali. The acid reacts with hardness salts and forms new, water-insoluble salts, which fall in the form of a sticky white mass onto clothes, hair, etc. This is not a very pleasant phenomenon well known to everyone who tried to wash or wash in hard water. ; secondly, the hydrolysis product of alkali destroys and reduces the strength of the fibers that make up the various tissues. Polyamide fibers (capron, nylon, perlon) are destroyed by soap especially intensively.

Information taken from the source.