Anionic surfactants examples. Surface-active substances (surfactants). Definition, composition, classification and scope. Chemical structure of surfactants

Chemically, this is a completely diverse group of substances, but the common thing is the following: if at least two substances do not dissolve in each other, such as oil and water, then the addition of a surfactant mixes them and forms a homogeneous liquid. This is very clearly visible in the case of washing dishes: the fat on the surface of the plates is very visible and noticeable, but water, especially cold water, flows over the fat, practically without washing it away. As soon as you pour at least a little detergent onto a plate containing surfactants and apply it evenly, the water will immediately drain, taking with it the remaining grease. Fat, like oil, does not dissolve in water and the application of a surfactant simply helped the oil to mix with water, creating a “dissolution” effect. In fact, the oil on the plate turned from a uniform layer on the surface into thousands of tiny droplets of oil surrounded by a layer of surfactants, which the water easily carried with it from the surface of the plate.

A surfactant molecule has two distinctive parts: a head and a tail. The head of the surfactant molecule is hydrophilic - loving water, and the tail is lipophilic (loving oil) and hydrophobic (afraid of water). When such a molecule enters water with drops of oil, the tail of the surfactant tries to leave the water and is located either in the oil or in the air, while the head, on the contrary, is located in the water. Thus, the molecule settles at the interface between water and oil and creates an emulsion.

Types of Surfactants

Depending on the chemical nature, they are distinguished: anionic, cationic, amphoteric and nonionic (nonionic) surfactants.

Anionic surfactants

Anionic surfactants (with a negatively charged head)- the most widely used detergent components in cosmetics. They are inexpensive, easy to make, and clean well. In addition, they are easily washed off from hair without forming films or deposits. Their cleaning effect is the same in both cold and hot water. The main disadvantage of anionic surfactants is that they can irritate the skin. To reduce irritation, other groups of surfactants are often added to formulations.
Anionic surfactants are the main detergent components of shampoos; to obtain an emulsifying effect, they are added to dyes.

Cationic surfactants

Cationic surfactants (with a positively charged head)- weaker detergents than anionic ones, and do not foam well. However, cationic surfactants work well as hair conditioners, giving softness and manageability to the hair. They can remove negative charges from hair, thereby providing an antistatic effect. Cationic surfactants “weight” the hair, making it more manageable, making it easier to comb and style.

Since cationic surfactants have a charge opposite to anionic surfactants, they were not previously mixed. Now it is possible to combine them in one bottle, thanks to which cationic surfactants soften the aggressive effect of shampoos, and when used as a conditioner they can neutralize the aggressive effect.
Cationic surfactants are most often found in conditioners and hair masks, as well as shampoos for colored hair and 2-in-1 shampoos. They can also be found in “tearless” children’s shampoos, as they do not cause eye irritation.

Amphoteric surfactants

Amphoteric surfactants may contain a positive or negative group depending on pH. Moreover, they can behave like cationic surfactants at lower pH values ​​and anionic surfactants at higher pH values. The lather of these surfactants is moderate and gives manageability to the hair. In addition, a group of amphoteric surfactants minimally irritates the scalp and is able to relieve existing irritation. 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 effects of conditioning additives, such as silicones and polymers, on hair and skin. Anionic surfactants are obtained from natural raw materials, so they are quite expensive components.
Amphoteric surfactants can be found in shampoos for children (they do not irritate the eyes), special shampoos for damaged and thin hair, 2-in-1 shampoos, hair dyes, oxidizers, as well as masks and conditioners.

Nonionic surfactants

Nonionic surfactants, the second most popular group of surfactants after anionic surfactants, have polar heads. They are the mildest of all surfactants and are used in combination with anionic surfactants as a secondary cleaner, thickener and foam stabilizer.
Non-ionic surfactants are found in almost all hair cosmetics, as they combine well with many substances.

Application of surfactants (surfactants)

Surfactants are widely used in industry, agriculture, medicine and everyday life. World production of surfactants is growing every year, and the share of nonionic substances in the total production output is constantly increasing. All types of surfactants are widely used in the production and use of synthetic materials. polymers. The most important area of ​​consumption of micelle-forming surfactants is the production of polymers by emulsion polymerization. The technology largely depends on the type and concentration of the selected surfactants (evulsifiers). and physico-chemical. properties of the resulting latexes. Surfactants are also used in suspension polymerization. Typically, high molecular weight surfactants are used - water-soluble polymers (volivinyl alcohol, cellulose derivatives, vegetable adhesives, etc.). By mixing varnishes or liquid oil-resin compositions with water in the presence of emulsifiers, emulsions are obtained that are used in the manufacture of plastics, leather substitutes, non-woven materials, impregnated fabrics, water-borne paints, etc.

In the production of paints and varnishes and plastics. Surfactants are added to regulate their rheology. characteristics.

A variety of surfactants are used for surface treatment of fibrous (woven and non-woven) and film materials (as antistatic agents, spinning solution modifiers, detergents. Among the surfactants used as water repellents, the most promising are organosilicon and fluorocarbon compounds. The latter, with the appropriate orientation of the molecules in the surface layer are able to prevent wetting of the material not only with water, but also with hydrocarbon liquids.

In the production of sponge rubber and foam plastics, surfactants are used as foam stabilizers.

High molecular weight water-soluble surfactants, in addition to being used in the above-mentioned technologies. processes, used as flocculants in various types of water treatment. With their help from waste and technological. water, as well as from drinking water, suspended contaminants are removed.

SURFACTIVE SUBSTANCES, adsorption of which from a liquid at an interface with another phase (liquid, solid or gaseous) leads to the following: lowering surface tension (see Surface activity). In max. general and practically important. In this case, the adsorbing surfactant molecules (ions) have a diphilic structure, i.e., they consist of a polar group and a nonpolar hydrocarbon radical (diphilic molecules). The hydrocarbon radical has surface activity towards the non-polar phase (gas, hydrocarbon liquid, non-polar surface of a solid), which is pushed out of the polar medium. In an aqueous solution of a surfactant, an adsorption agent is formed at the border with air. monomolecular layer with hydrocarbon radicals oriented towards the air. As it becomes saturated, the surfactant molecules (ions), compacting in the surface layer, are located perpendicular to the surface (normal orientation).

Surfactant concentration in adsorb. layer on several. orders of magnitude higher than in the volume of liquid, therefore, even with a negligible content in water (0.01-0.1% by weight), surfactants can reduce the surface tension of water at the interface with air from 72.8 10-3 to 25 10 -3 J/m2, i.e. almost to the surface tension of hydrocarbon liquids. A similar phenomenon occurs at the interface between an aqueous surfactant and a hydrocarbon liquid, which creates the prerequisites for the formation of emulsions.

Depending on the state of the surfactant in the solution, true solutions (molecularly dispersed) and colloidal surfactants are conventionally distinguished. The conditionality of this division is that the same surfactant can belong to both groups, depending on the conditions and chemistry. nature (polarity) of the r-ritel. Both groups of surfactants are adsorbed at phase boundaries, i.e., they exhibit surface activity in solutions, while bulk properties associated with the appearance of a colloidal (micellar) phase exhibit only colloidal surfactants. These groups of surfactants differ in the value of the dimensionless quantity, called. hydrophilic-lipophilic balance (HLB) and is determined by the ratio:

where is the affinity (free interaction energy) of the non-polar part of the surfactant molecule to the hydrocarbon liquid (b is a dimensionless parameter depending on the nature of the surfactant, is the free interaction energy per one CH2 group, v is the number of CH2 groups in the hydrocarbon radical), a-affinity of the polar group for water. For colloidal surfactants (b + or, where the indices m correspond to the minimum affinity values, at which the colloidal properties of the surfactant begin to appear. The minimum number of carbon atoms in the radical for different types of colloidal surfactants lies in the range of 8-12, i.e. That is, colloidal surfactants have a fairly large hydrocarbon radical. At the same time, colloidal surfactants must also have true pH in water, i.e., the polarity of the hydrophilic group must also be quite high. This corresponds to the condition:

In the beginning. 60s 20th century D. Davis developed an HLB scale with values ​​from O to 40. Surfactants with lipophilic properties have low HLB values, while those with hydrophilic properties have high values. Each group of atoms included in a surfactant molecule is assigned a group number. By adding these numbers, the GLB according to the following formula is obtained:

HLB = hydrophilic group numbers + 4- hydrophobic group numbers + 7.

Although the concept of HLB is quite formal, it allows one to determine the areas of application of surfactants. So, for the formation of water/oil emulsions, HLB ranges from 3-6, oil/water emulsions - 8-16, for wetting agents - 7-9, for detergents - 13-15.

The surface activity of surfactants belonging to different groups is determined differently. For true r-rim surfactants it is equal to max. the value of the derivative and is measured from the initial portion of the adsorption isotherm s(c) at c0 (G is the number of moles of surfactants adsorbed per unit surface area, R is the gas constant, T is the absolute temperature). For colloidal surfactants, surface activity Gmin = (s0 - smin)/smin, where s0 is the surface tension of pure p-solvent, sMIH is the smallest (constant) value of s, and cmin is the surfactant concentration corresponding to this value. Further introduction of a surfactant into the solution leads to an increase in the number of micelles, and the concentration of the molecularly dispersed surfactant remains constant. The value of smin-critical. micelle concentration (KKM). It is defined as the concentration of a surfactant, at which a large number of micelles appear in the solution, which are in thermodynamics. equilibrium with molecules (ions), and the properties of the solution change sharply (electrical conductivity, surface tension, viscosity, light scattering, etc., see Micelle formation).

Classification of surfactants. This article describes the classification adopted at the III International Congress on Surfactants and recommended by the International Organization for Standardization (ISO) in 1960. It is based on chemistry. the nature of molecules and includes four basic. class of surfactants: anionic, cationic, nonionic and amphoteric. Sometimes high molecular weight is also isolated. (polymer), perfluorinated and Kremniorg. Surfactant, however, according to chemistry. the nature of the molecules of these surfactants may. classified as one of the above. classes.

Anionic surfactants contain one or more in a molecule. polar groups and dissociate in an aqueous solution to form long-chain anions, which determine their surface activity. These are the groups: COOH(M), OSO2OH(M), SO3H(M), where M is a metal (mono-, di- or trivalent). The hydrophobic part of the molecule is usually represented by saturated or unsaturated aliphatic. chains or alkyl aromatic. radicals. There are 6 groups of anionic surfactants.

1) Derivatives of carbon compounds (soaps): RCOOM, ROOC (CH2)nCOOM, RC6H4 (CH2)nCOOM, RCH=CH -- --(CH2)nCOOM. 2) Primary and secondary alkyl sulfates ROSO3M, R"R: CHOSO3M, alkylaryl ethyl sulfates RC6H4C2H4OSO3M, alkylcyclohexyl ethyl sulfates RC6H10C2H4OSO3M, etc. (see Avirol, Alizarin oil, Alkyl sulfates). 3) Alkyl and alkyl benzene sulfonates, sulfonates esters mono- and dicarbonic compounds: RSO3M, RC6H4SO3M, ROOCCH2SO3M, ROOCCH2CH(COOR)SO3M (see Alkylbenzenesulfonates, Naphthalene sulfonates, Sulfonates). 4) Sulfo- and carboxyethoxylates of alcohols, sulfoethoxylates of carbonic compounds, sulfoethoxylates of alkylphenylethyl alcohols, di metal personal salts of sulfosuccinic acid, salts of unsaturated sulfates: RO(C2H4O)nSO3M, RO(C2H4O)nCH2COOM, RCOO (C2H4O)n SO3M, RC6H4 (C2H4O)2 SO3M, ROOCCH2CH (COOM) SO3M, RCH ( OSO3M)=CH (CH2)n--COOM. 5) Nitrogen-containing surfactants: amidosulfonates RCONR"--R:--SO3M, amidosulfonates RR"NOC--R:--SO3M, amidosulfates RCONR"-R: --OSO3M, amidocarboxylates RCO(NH-R"--CO)nOM, compounds with carboxy and sulfo groups RCONH--R--OCOR:(SO3M) --COOM. Instead of an amide group in many such compounds M.B. also sulfoamide group, e.g. RC6H4SO2NHCH2CH2SO3M. 6) Perfluorinated salts. carbon kit, perfluorinated sulfoacetates, mono- and dialkyl-phosphates and phosphonates, perfluorinated. phosphonates and other compounds.

In anionic surfactants, the cation may. not only metal, but also org. basis. This is often di- or triethanolamine. Surface activity begins to appear at the length of the C8 hydrocarbon hydrophobic chain and increases with increasing chain length until the complete loss of the surfactant's pH in water. Depending on the structure, the intervals. functional groups and hydrophilicity of the polar part of the molecule, the length of the hydrocarbon part can reach up to C18. The benzene ring corresponds to approximately 4 C atoms, the perfluorinated methylene group CF2 corresponds to approximately 2.5-3 methylene groups.

Naib. alkyl sulfates and alkylaryl sulfonates are common. Optim. Primary dodecyl sulfate and straight-chain dodecylbenzene sulfonate have surfactant properties. These substances are thermally stable, low-toxic (LD50 1.5-2 g/kg, white mice), do not irritate human skin and are satisfactorily biol. decomposition in bodies of water (see below), with the exception of alkylaryl sulfonates with a branched alkyl chain. They combine well with other surfactants, exhibiting synergism; their powders are non-hygroscopic. Secondary alkyl sulfates have good foaming ability, but are thermally unstable and are used in liquid form. Secondary alkyl sulfonates have high surface activity, but are very hygroscopic. Promising surfactants are those whose hydrophilic part consists of several. functional groups. For example, disodium salts of sulfosuccinic acid have good sanitary and hygienic properties. St. you along with high colloid-chemical. and technol. indicators when dissolved in hard water. Surfactants containing a sulfonamide group have biol. activity. Dodecyl phosphate also has good properties.

Called cationic. Surfactants whose molecules dissociate in an aqueous solution to form a surface-active cation with a long hydrophobic chain and an anion, usually a halide, sometimes a sulfuric or phosphoric anion. The predominant ones among cationic surfactants are nitrogen-containing compounds; practical Ingredients that do not contain nitrogen are also used: com. sulfonium +X- and sulfoxonium +X-, phosphonium + X-, arsonium + X-, iodonium (formula I). Nitrogen-containing compounds can be divided into the following. basic groups: 1) amines and their salts RNR"R: HX; 2) mono- and bi-quaternary ammonium compounds aliphatic structures + X-, 2+2Х-, compounds with mixed aliphatic and aromatic structure 2 + 2Х- ; 3) quaternary ammonium compounds with different functional groups in the hydrophobic chain; 4) mono- and biquaternary ammonium compounds with a nitrogen atom in the heterocyclic ring. The last group unites hundreds of surfactants of industrial importance. The most important of them are compounds of pyridine, quinoline, phthalazine, benzimidazole, benzothiazole, benzotriazole, derivatives of pyrrolidine, imidazole, piperidine, morpholine, piperazine,

benzoxazine, etc.; 5) amine oxides RR"R:N+O- (industrial production started); 6) polymer surfactants (II). Polyvinylpyridinium halides are mainly used.

surfactant molecular

Cationic surfactants reduce surface tension less than anionic surfactants, but they can interact. chemically with the surface of the adsorbent, for example. with cellular proteins of bacteria, causing a bactericidal effect. Interaction polar groups of cationic surfactants with hydroxyl groups of cellulose fibers leads to hydrophobization of fibers and impregnation of tissues.

Nonionic surfactants do not dissociate into ions in water. Their pH value is due to the presence in the molecules of hydrophilic ether and hydroxyl groups, most often a polyethylene glycol chain. Apparently, upon dissolution, hydrates are formed due to the formation of hydrogen bonds between the oxygen atoms of the polyethylene glycol residue and water molecules. Due to the rupture of the hydrogen bond, as the temperature increases, the pH of nonionic surfactants decreases, so for them the cloud point is up. The temperature limit of micellization is an important indicator. Mn. compounds containing a mobile H atom (compounds, alcohols, phenols, amines), reacting with ethylene oxide, form nonionic surfactants RO (C2H4O)n H. The polarity of one oxyethylene group is significantly less than the polarity of any acidic group in anionic surfactants. Therefore, to impart the required hydrophilicity and HLB value to a molecule, depending on the hydrophobic radical, from 7 to 50 oxyethylene groups are required. A characteristic feature of nonionic surfactants is their liquid state and low foaming in aqueous solutions.

Nonionic surfactants are divided into groups that differ in the structure of the hydrophobic part of the molecule, depending on what substances served as the basis for the production of polyglycol ethers. Based on alcohols, ethoxylated alcohols RO(C2H4O)nH are obtained; based on carboxylic acids - ethoxylated fatty acids RCOO (C2H4O)n H; based on alkylphenols and alkylnaphthols - ethoxylated alkylphenols RC6H4O(C2H4O)nH and comp. RC10H6O--- (C2H4O)nH; based on amines, amides, imidazolines - ethoxylated alkylamines RN[ (C2H4O)n H]2, comp. RCONH(C2H4O)nH, comp. Forms III; based on sulfonamides and mercaptans - surfactants such as RSO2NC(C2H4O)nH]2 and RS(C2H4O)nH. A separate group consists of proxanols (pl u r o n i k s) - block copolymers of ethylene and propylene oxides HO (C2H4O)x (C3H6O)y (C2H4O)z H, where x, y and z vary from several. units to several tens, and proxamines (tetronics; form IV) - block copolymers of ethylene and propylene oxides, obtained in the presence. ethylenediamine. Alkylacetylene glycols serve as the basis for the production of surfactants of the type H(OC2H4)n--OCR"R:CCCR"R""O (C2H4O)nH; phosphorus esters of the type (RO)2P(O)O(C2H4O)nH; pentaerythritol ethers of type V. Nonionic surfactants are the products of condensation of glycosides with fatty alcohols, carbonates and ethylene oxide. There are also surfactants of the sorbital group (Tweens, type VI) - products of the addition of ethylene oxide to sorbitone monoester and fatty acid. Kremniorg constitutes a separate group. Surfactant, eg. (CH3)3Si n--(CH2)3O(C2H4O)mH.

The production of nonionic surfactants in most cases is based on the addition of ethylene oxide at elevated levels. t-re under pressure in the presence. catalysts (0.1-0.5% CH3ONa, KOH or NaOH). In this case, the result is an average one. the content of polymer homologs, in which the molecular weight distribution is described by the Poisson function. Individual substances are obtained by adding polyhalogen-substituted polyethylene glycols to alcoholates. Colloidal chemical The properties of surfactants of this class vary widely depending on the length of the hydrophilic polyglycol chain and the length of the chain of the hydrophobic part in such a way that decomp. representatives of one homologous row m.b. good wetting agents and emulsifiers. The surface tension of homologues of ethoxylated alkylphenols and primary alcohols at a constant content of ethylene oxide groups decreases in accordance with Traube’s rule, i.e., with each addition. CH2 group reduces surface tension. In optimal option it can reach (28-30) 10-3 N/m at critical. micelle concentrations. The micellar mass is very large; for twins, for example, it reaches 1800. Nonionic surfactants are less sensitive to salts that cause water hardness than anionic and cationic surfactants. The wetting ability of nonionic surfactants depends on the structure; optim. A surfactant with a branched structure has a wetting ability:

Hydroxyethylated alcohols C10-C18 with n from 4 to 9 and pluronics form spontaneous oil/water and water/oil microemulsions. Nonionic surfactants combine well with other surfactants and are often included in detergent formulations.

Amphoteric (ampholytic) surfactants contain in the molecule a hydrophilic radical and a hydrophobic part that can be a proton acceptor or donor, depending on the pH of the solution. Typically these surfactants include one or more. basic and acidic groups, may also contain a nonionic polyglycol group. Depending on the pH value, they exhibit the properties of cationic or anionic surfactants. At certain pH values, called. isoelectric point, surfactants exist in the form of zwitterions. The ionization constants of acidic and basic groups of true p-rime amphoteric surfactants are very low, but cation-oriented and anion-oriented zwitterions are most common. The cationic group is usually a primary, secondary or tertiary ammonium group, a pyridine or imidazoline residue. In principle, instead of N m.b. atoms S, P, As, etc. Anionic groups are carboxyl, sulfonate, sulfoester or phosphate groups.

According to chemistry Based on their structure and certain similarities, ampholytic surfactants are divided into 5 main categories. groups: 1) alkylaminocarbon compounds RNH (CH2)n COOH; The alkyl radical of an amine is usually normal (straight chain), but if it is located between the amine group and the carboxyl group, it sometimes has a branched character. This group also includes alkylamino-phenylcarbonic acids RNHC6H4COOH; alkylaminocarbon compounds with a primary, secondary or tertiary amino group RCH (NH2) COOH, RCH (NHR) COOH, R(CH3)NCH2COOH; with int. a hydroxyl, ether, ester, amide or sulfoamide group; substances with two or more amino and amido groups, with several amino and hydroxyl groups.

• 2) Alkyl betaines are the most important group of zwitterionic surfactants. They can be divided into 5 main ones. groups: a) alkyl betaines -C-alkyl betaines RCH COO- and N-alkyl betaines RN+(CH3)2 CH2COO-; b) sulfite-, sulfo-, sulfate- and phosphate betaines RN+(CH3)2CH2CH2 RN+(CH3)2CH2CH2, RC6H4CH2N+(CH3)2CH2CH2 RN+(CH3)2CH2CH(OH)CH2OP; c) amidobetaines RCONH(CH2)3 N+(CH3)2COO-; d) ethoxylated betaines RN+[(C2H4O)pH][(C2H4O)gH]CH2COO-; e) other zwitterionic surfactants.
• 3) Alkylimidazoline derivatives, in the molecules of which the anionic and cationic groups have approximately the same ionization constants (forms VII and VIII), where R-alkyl C7-C17, R"-H, Na, CH2COOM (M-metal). According to the structure and methods of synthesis, betaine surfactants are distinguished, including carboxy-, sulfo-, sulfate or sulfoether group [form IX; R" = (CH2)nCOO-, (CH2)3, CH2CH(OH)CH2 ] and others ( "non-betaine") imidazoline surfactants [form X; R" = CH2COONa, (CH2)2 N (CH2COOH)2, (CH2)2 N= =CHC6H4SO3H, (CH2)2 OSO3H]. The balance of ionizing groups provides these compounds with good colloid-chemical and sanitary-hygienic .saint.
• 4) Alkylaminoalkanesulfonates and sulfates (AAAC1 and AAAC2, respectively). Anion-landmark. substances easily transform into zwitterionic form, which makes it possible to isolate them in their pure form. The ionization constant of the acidic group is much greater than the basic one, so they are used in an alkaline environment. However, in the case of several basic groups and in the presence of other hydrophilic groups next to the acidic group, these substances are similar in properties and areas of application to ampholytic surfactants and have a bactericidal effect. Depending on the ionization constants, salts AAAC1 RN(R")-R:--SO3M, AAAC2 RN(R")-R: -- OSO3M, aromatic derivatives can be distinguished. aminosulfonic acids RR"N--Ar--SO3M, aminosulfonates with N atom in heterocycles (form XI); aminophosphates, aminophosphonates and other amino compounds: compounds of type RR"R:P(O)(OH)2, RR "R""OP(O)(OH)2, where R and R" are long and short hydrocarbon radicals, R: is a short divalent radical; conn. RN(CH2CH2SO3Na)2. Their difference is their good ability to disperse calcium soaps and resistance to water hardness salts.
• 5) Polymer ampholytic surfactants: natural (proteins, nucleic acids, etc.); modified natural (oligomeric protein hydrolysates, sulfate chitin); products of stepwise condensation of amines, formaldehyde, albumin, fatty acids; cellulose derivatives obtained by introducing carboxyl and diethanolamineethyl groups; synthetic, whose molecules combine the structural features of all the above groups of amphoteric surfactants (see, for example, formulas XII-XVI).

Application of surfactants. World production of surfactants is 2-3 kg per capita per year. Approximately 50% of the produced surfactants are used for household chemicals (washing and cleaning products, cosmetics), the rest is used in industry and agriculture. x-ve. Simultaneously with the annual increase in the production of surfactants, the ratio between their use in everyday life and industry changes in favor of industry.

The use of surfactants is determined by their surface activity and adsorption structure. layers and volumetric saints. Surfactants of both groups (true r-rime and colloidal) are used as dispersants for grinding solids, drilling hard rocks (hardness reducers), to improve the lubrication effect, reduce friction and wear, the intensity of oil recovery, etc. Others. An important aspect of the use of surfactants is the formation and destruction of foams, emulsions, and microemulsions. Surfactants are widely used to regulate the structure formation and stability of dispersed systems with a liquid dispersion medium (aqueous and organic). Micellar systems formed by surfactants in both aqueous and non-aqueous media are widely used, for which it is not the surface activity of the surfactants or their adsorption properties that are important. layers, and volume properties: pronounced viscosity anomalies with an increase in surfactant concentration up to the formation, for example. in an aqueous environment, crystallization. solid soap structures or solid-shaped structures (in petroleum oil-based greases).

Surfactants are used in more than 100 sectors of the national economy. Most of the surfactants produced are used in detergents, in the production of fabrics and synthetic-based products. and natural fibers Major consumers of surfactants include the oil and chemical industries. industry, industry is building. materials and a number of others. Naib. important applications of surfactants:

• - drilling with clay solutions and reversible water/oil emulsions. To regulate aggregative stability and rheological. characteristics of the solutions, high-commol is used. Surfactants - water-soluble cellulose ethers, poly-acrylamide, etc., calcium salts of nature are introduced into the emulsions. and synthetic fatty acids (C16-C18 and above), alkyl aromatic. sulfonates, alkylamines, alkylamidoamines, alkylimidazolines;
• -increased oil recovery through micellar flooding (ethoxylated alkylphenols and alcohols, alkyl aromatic sulfonates);
• - antioxidant, extreme pressure and other additives in the production of minerals. oils (synthetic fatty soaps, petroleum sulfonates, oxyethyl alcohols) and plastics. lubricants (phenol derivatives, arylamines, alkyl and aryl phosphates);
• - regulation of wetting during flotation of iron and manganese ores (natural and synthetic fatty soaps, higher aliphatic amines), rare metal ores (alkylarsone and alkylphosphonic acids, alkyl aromatic sulfonates);
• -emulsion polymerization, production of polystyrene and other vinyl polymers (carboxymethylcellulose, polyvinyl alcohol, synthetic fatty soaps, alkyl sulfates, ethoxylated alcohols and alkylphenols);
• - chemical production fibers (oxyethylene amines and amides, proxanols and proxamines, higher alcohols and compounds);
• -fur. metal processing: adsorption. decrease in strength, increase in cutting, planing, milling speeds (natural and synthetic fatty soaps, alkyl aromatic sulfonates, oxyethyl alcohols, etc.);
• -industry is being built. materials: regulation of fur. and rheo-logical. St. in concrete mixtures due to adsorption. modification of components (esters of synthetic fatty acids, sulfonates, alkylamines, alkyl sulfates, oxyethyl fatty acids);
• -production of synthetic detergents;
• -improving soil structure, preventing erosion processes (surfactant polyelectrolytes - products of incomplete hydrolysis of polyacrylonitrile, amidation products of polyacrylic and polymethacrylic compounds, and the composition of the polymer chain varies among amide, cyclic imide, carboxyl and other groups).

Biological decomposition of surfactants. Aqueous solutions of surfactants in greater or lesser concentrations enter industrial wastewater. waters and ultimately into reservoirs. Much attention is paid to the purification of wastewater from surfactants, since due to the low rate of decomposition of surfactants, the harmful results of their impact on nature and living organisms are unpredictable. Wastewater containing hydrolysis products of polyphosphate surfactants can cause intensive plant growth, which leads to pollution of previously clean water bodies: as plants die, they begin to rot, and the water is depleted of oxygen, which in turn worsens the conditions for the existence of other forms of life in the water.

Among the methods of wastewater treatment in settling tanks are the conversion of surfactants into foam, adsorption with active carbon, the use of ion exchange resins, neutralization with cationic substances, etc. These methods are expensive and not effective enough, therefore it is preferable to purify wastewater from surfactants in settling tanks (aeration tanks) and in natural conditions (in reservoirs) by biol. oxidation under the influence of heterotrophic bacteria (the predominant genus is Pseudomonas), which are part of activated sludge. In relation to this process, surfactants are usually divided into “soft” and “hard”. Hard surfactants include certain alkylbenzenesulfonates (for example, tetrapropylbenzenesulfonate) and oxyethylene. isooctylphenols; at present they are practically not produced. The degree of biooxidation of the so-called. soft surfactants depends on the structure of the hydrophobic part of the surfactant molecule: when it is branched, biooxidation sharply worsens. Theoretically, biooxidation proceeds to conversion. org. in-in water and carbon dioxide, practically. the problem comes down only to the time of oxidation, i.e., to the kinetics of the process. If they graduate. oxidation occurs slowly, the surfactant has time to produce a harmful effect on living organisms and nature. Wednesday.

With biochemical When cleaning waste surfactant solutions, oxidation is carried out in the presence of enzymes. As the temperature increases, the oxidation rate increases, but above 350C the enzymes are destroyed. Anionic surfactants are adsorbed at the interfacial interfaces, as a result of which the enzymatic hydrolysis of fats, proteins and carbohydrates is reduced, leading to inhibition of bacterial activity.

The mechanism of biooxidation of surfactants is established by studying the intermediates. decomposition products. So, in between. the following products were found in the decomposition products of alkylbenzenesulfonates: alkylbenzenesulfonates with a short alkyl chain; sulfophenylcarbonaceous compounds with an average of 4 C atoms in the chain; sulfocarbonate compounds with 5-6 C atoms; sulfonic acids and sulfonic acids. This suggests that biodegradation starts from the terminal methyl group. The closer the residue moves to the benzene ring, the slower the oxidation occurs. The final stage is the decomposition of the benzene ring into unsaturation. compounds, which oxidize quite quickly and completely.

Alifatich. Surfactants oxidize faster than cyclic ones, and sulfonates are more difficult to oxidize than sulfates.

Apparently, this is due to the fact that sulfates in water are hydrolyzed. Straight-chain primary and secondary alkyl sulfates are completely destroyed in wastewater within 1 hour. Branched chain alkyl sulfates oxidize more slowly, while straight chain alkyl benzene sulfonates completely decompose in only 3 days. The biodegradation of cationic surfactants has been little studied; some researchers do not recommend disposing of them into wastewater.

The growth of surfactant production has led to the emergence of large enterprises that are local sources of water pollution. Highly concentrated wastewater from these enterprises may be microbiol purified a method based on the use of highly active cultures of microorganisms. Strains of bacteria were obtained that destroy alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, sulfoethoxylates, etc. Intermediates were identified. decomposition products, which are analogues of nature. in-c, non-toxic and do not have an adverse effect on the environment. One of the important results of bacterial digestion is the absence of intermediates. decomposition products of substances with clearly expressed diphilicity of molecules. The method gave will put. results for wastewater containing 500 mg/l surfactant. The cleaning efficiency was 95-97% in no more than 12 hours. Among gram-negatives. bacteria, microorganisms (destructors) were found that absorb surfactants as nutrition. substrate.

Technological surfactants and their lubricity

Surfactants (surfactants) are chemical compounds that, concentrating at the interface, cause a decrease in surface tension.

The significant effect of technological surfactants is expressed in both direct and indirect (through changes in structure) influence on surface phenomena at the lubricant-metal interface, i.e. on the lubricating and protective ability of lubricants. Not only individual surfactants, but also oxidation products formed during the preparation process (i.e., TPAS) and operation of lubricants have a significant impact on the processes of friction and wear. Back in the 1950s, D.S. Velikovsky and his colleagues developed additives of the MNI series, which are products of the oxidation of petrolatum or ceresin. It has been shown that the carriers of their functional properties, including anti-wear, are ester acids containing active groups COOH, COOC, OH, as well as lactone groups forming quasicrystalline structures.

Surfactants have a polar (asymmetric) molecular structure, are able to be adsorbed at the interface of two media and reduce the free surface energy of the system. Quite insignificant additions of surfactants can change the properties of the particle surface and give the material new qualities. The action of surfactants is based on the phenomenon of adsorption, which simultaneously leads to one or two opposite effects: a decrease in the interaction between particles and stabilization of the interface between them due to the formation of an interphase layer. Most surfactants are characterized by a linear structure of molecules, the length of which significantly exceeds the transverse dimensions (Fig. 15). Molecular radicals consist of groups that are related in their properties to solvent molecules, and of functional groups with properties that are sharply different from them. These are polar hydrophilic groups, having pronounced valence bonds and having a certain effect on wetting, lubricating and other actions associated with the concept of surface activity . At the same time, the supply of free energy decreases with the release of heat as a result of adsorption. Hydrophilic groups at the ends of hydrocarbon non-polar chains can be hydroxyl - OH, carboxyl - COOH, amino - NH 2, sulfo - SO and other strongly interacting groups. Functional groups are hydrophobic hydrocarbon radicals characterized by side valence bonds. Hydrophobic interactions exist independently of intermolecular forces, being an additional factor that promotes the approaching, “sticking together” of non-polar groups or molecules. The adsorption monomolecular layer of surfactant molecules is oriented with the free ends of the hydrocarbon chains away from

surface of the particles and makes it non-wettable, hydrophobic.

The effectiveness of a particular surfactant additive depends on the physicochemical properties of the material. A surfactant that produces an effect in one chemical system may have no effect or a clearly opposite effect in another. In this case, the surfactant concentration is very important, determining the degree of saturation of the adsorption layer. Sometimes high molecular weight compounds exhibit an effect similar to surfactants, although they do not change the surface tension of water, for example polyvinyl alcohol, cellulose derivatives, starch and even biopolymers (protein compounds). The effect of surfactants can be exerted by electrolytes and substances insoluble in water. Therefore, it is very difficult to define the concept of “surfactant”. In a broad sense, this concept refers to any substance that, in small quantities, noticeably changes the surface properties of a dispersed system.

The classification of surfactants is very diverse and in some cases contradictory. Several attempts have been made to classify according to different criteria. According to Rebinder, all surfactants according to their mechanism of action are divided into four groups:

– wetting agents, defoamers and foam formers, i.e. active at the liquid-gas interface. They can reduce the surface tension of water from 0.07 to 0.03–0.05 J/m2;

– dispersants, peptizers;

– stabilizers, adsorption plasticizers and thinners (viscosity reducers);

– detergents with all the properties of surfactants.

The classification of surfactants by functional purpose is widely used abroad: thinners, wetting agents, dispersants, deflocculants, foaming agents and defoamers, emulsifiers, disperse system stabilizers. Binders, plasticizers and lubricants are also distinguished.

Based on their chemical structure, surfactants are classified depending on the nature of hydrophilic groups and hydrophobic radicals. Radicals are divided into two groups - ionic and nonionic, the former can be anionic and cationic.

Nonionic surfactants contain non-ionizing final groups with high affinity for the dispersion medium (water), which usually include atoms of oxygen, nitrogen, and sulfur. Anionic surfactants are compounds in which a long hydrocarbon chain of molecules with low affinity for the dispersion medium is part of the anion formed in an aqueous solution. For example, COOH is a carboxyl group, SO 3 H is a sulfo group, OSO 3 H is an ether group, H 2 SO 4, etc. Anionic surfactants include salts of carboxylic acids, alkyl sulfates, alkyl sulfonates, etc. Cationic substances form cations containing a long hydrocarbon radical in aqueous solutions. For example, 1-, 2-, 3- and 4-substituted ammonium, etc. Examples of such substances can be amine salts, ammonium bases, etc. Sometimes a third group of surfactants is isolated, which includes amphoteric electrolytes and ampholytic substances, which, depending on By nature, the dispersed phase can exhibit both acidic and basic properties. Ampholytes are insoluble in water, but are active in non-aqueous media, such as oleic acid in hydrocarbons.

Japanese researchers propose a classification of surfactants according to physicochemical properties: molecular weight, molecular structure, chemical activity, etc. The gel-like shells on solid particles resulting from surfactants as a result of different orientations of polar and non-polar groups can cause various effects: liquefaction; stabilization; dispersing; defoaming; binding, plasticizing and lubricating actions.

The surfactant has a positive effect only at a certain concentration. There are very different opinions on the issue of the optimal amount of administered surfactants. P. A. Rebinder points out that for particles

1–10 µm the required amount of surfactant should be 0.1–0.5%. Other sources give values ​​of 0.05–1% or more for different dispersion. For ferrites, it was found that in order to form a monomolecular layer during dry grinding, surfactants must be taken at the rate of 0.25 mg per 1 m 2 of the specific surface of the initial product; for wet grinding – 0.15–0.20 mg/m2. Practice shows that the surfactant concentration in each specific case must be selected experimentally.

In the technology of ceramic SEMs, four areas of application of surfactants can be distinguished, which make it possible to intensify physicochemical changes and transformations in materials and control them during the synthesis process:

– intensification of the processes of fine grinding of powders to increase the dispersion of the material and reduce the grinding time when achieving a given dispersion;

– regulation of the properties of physical and chemical disperse systems (suspensions, slips, pastes) in technological processes. What is important here are the processes of liquefaction (or a decrease in viscosity with an increase in fluidity without a decrease in moisture content), stabilization of rheological characteristics, defoaming in disperse systems, etc.;

– control of torch formation processes when spraying suspensions when obtaining the specified size, shape and dispersion of the spray torch;

– increasing the plasticity of molding compounds, especially those obtained when exposed to elevated temperatures, and the density of manufactured blanks as a result of the introduction of a complex of binders, plasticizers and lubricants.

Surfactants (surfactants) are, as a rule, chemical substances that are contained in any cleaning product, even ordinary soap. It is thanks to surfactants that the cleaning product cleans.

Why are surfactants needed?

The problem is that dirt, especially grease, is very difficult to wash off with water. Try washing your oily hands with water. The water will drain without washing away the fat. Water molecules do not stick to fat molecules and do not take them with them. Therefore, the task is to attach fat molecules to water molecules. This is exactly what surfactants do. A surfactant molecule is a sphere, one pole of which is lipophilic (connects with fats), and the other is hydrophilic (connects with water molecules). That is, one end of a surfactant particle is attached to a fat particle, and the other end is attached to water particles.

How do surfactants affect our health?

Most of the moisture in the human body is also based on fat. Those. for example, the protective layer of the skin (lipids - fats that protect the skin from various bacteria entering the body) is a fatty film and is naturally destroyed by surfactants. And the infection attacks the place that is least protected, which is of course harmful to human health. Experts say that after using a detergent, the protective layer of the skin should have time to recover within 4 hours to at least 60%. These are the hygiene standards established by GOST. However, not all detergents provide such skin restoration. And fat-free and dehydrated skin ages faster.

In addition, non-biodegradable surfactants can accumulate in the brain, liver, heart, fat deposits (especially a lot) and continue to destroy the body for a long time. And since almost no one can do without detergents, surfactants are constantly replenished in our body, causing continuous harm to the body. Surfactants also affect reproductive function in men, similar to radioactive radiation.

The problem is aggravated by the fact that our treatment facilities do a poor job of removing surfactants. Therefore, harmful surfactants return to us through the water supply in almost the same concentration in which we pour them into the drain. The only exceptions are products with biodegradable surfactants.

What types of surfactants are there?

Anionic surfactants. The main advantage is the relatively low cost, efficiency and good solubility. But they are the most aggressive towards the human body.
- Cationic surfactants. They have bactericidal properties.
- Nonionic surfactants. The main advantage is its beneficial effect on fabric and, most importantly, 100% biodegradability.
- Ampholytic surfactants. Depending on the environment (acidity/alkalinity), they act as either cationic or anionic surfactants.

How do surfactants affect the environment?

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 rate of CO2 and oxygen in the water mass. And this negatively affects aquatic flora and fauna.

In addition, almost all surfactants used in industry and households, when they fall on particles of earth, sand, or clay, under normal conditions can release heavy metal ions held by these particles, and thereby increase the risk of these substances entering the human body.

What is a biodegradable surfactant?

One of the main criteria for the environmental safety of household chemicals is the biodegradability of surfactants that are included in their composition. Surfactants are divided into those that are quickly destroyed in the environment and those that are not destroyed and can accumulate in organisms in unacceptable concentrations.

Moreover, a distinction is made between primary biodegradability, which implies structural changes in surfactants by microorganisms, leading to the loss of surface-active properties, and complete biodegradability - the final biodegradation of surfactants to carbon dioxide and water. Only completely biodegradable surfactants are safe.

Only some nonionic surfactants, primarily those obtained from biological raw materials rather than petroleum products, are 100% biodegradable.

Bio-surfactant - what is it?

In 1995, ECOVER, together with the French company Agro-Industrie Recherches et Développements (ARD), took part in a European research project, the goal of which was to learn how to synthesize surfactants from agricultural waste, such as straw and wheat bran. The project was successfully completed back in 1999, and production on an industrial scale began in 2008.

Nowadays, bio-surfactants form the basis of the entire line of ECOVER brand dishwashing detergents. Test results confirm that such surfactants have a strong cleaning effect, are completely biodegradable and are characterized by low toxicity. It's like a fairy tale where straw turned to gold, but this is a real story.

Polar groups in anionic surfactants are usually carboxylate, sulfate, sulfonate and phosphate groups. In Fig. Figure 1 shows the molecular structures of the most common surfactants of this class.

Anionic surfactants are used in much larger quantities than other types of surfactants. According to a rough estimate, the world production of surfactants is 10 million tons per year, of which 60% is the share of anionic surfactants.

Rice. 1. Structures of some typical anionic surfactants

The main reason for the popularity of these surfactants is their simplicity and low cost of production. Anionic surfactants are part of most detergents, and surfactants with alkyl or alkylaryl groups containing 12-18 carbon atoms in the hydrophobic chain have the best cleaning effect.

The counterions are usually Na +, K +, NH4 +, Ca 2+ ions and various protonated alkylamines. Sodium and potassium ions increase the solubility of surfactants in water, while calcium and magnesium ions help increase the solubility of surfactants in the oil phase. Protonated amines and alkanolamines ensure the solubility of surfactants in both phases.

Soaps also constitute a huge class of surfactants. They are produced by saponification of natural oils and fats. Usually soaps are called alkali metal salts of carboxylic acids obtained from animal fats or vegetable oils. Bar soaps typically contain fatty acids that are derived from tall oil, palm oil and coconut oil. When used under optimal conditions, soaps are ideal surfactants. Their main drawback is sensitivity to hard water, which determined the need to create synthetic surfactants. A very specific application is found in the lithium salt of a fatty acid, namely lithium 12-hydroxystearate, which is used as the main component of lubricants.

Alkylbenzene sulfonates constitute a group of synthetic surfactants that are considered to be the main “workhorses”. They are widely used in household cleaning products, as well as in a wide variety of industrial applications. They are obtained through the sulfonation process of alkylbenzenes. In large-scale synthesis, sulfur trioxide is most often used as the sulfonating agent, but other substances such as sulfuric acid, oleum, chlorosulfonic acid, or amidosulfonic acid can also be used. In some cases they turn out to be even more preferable. Industrial synthesis is carried out in a continuous process using a free-flowing film apparatus. The first stage of the process produces pyrosulfonic acid, which reacts slowly and spontaneously further to form sulfonic acid.

The sulfonic acid is then neutralized with caustic soda, resulting in the formation of an alkylbenzenesulfonate salt. Due to the large volume of alkyl substituents, n-sulfonic acids are formed almost exclusively. In the diagram above, R is an alkyl group, typically containing 12 carbon atoms. Initially, branched alkylbenzenes were used as an intermediate product in the synthesis of surfactants, but nowadays they are almost completely replaced by linear derivatives, therefore such surfactants are called linear alkylbenzenesulfonates. The rejection of branched derivatives and their replacement with linear ones is mainly due to their faster biodegradation. Alkylbenzenes are in turn prepared by alkylation of benzene with n-alkenes or alkyl chlorides using HF or AICI3 as catalysts. The reaction produces a mixture of isomers with a phenyl group attached to one of the non-terminal positions in the alkyl chain.

Another type of sulfonate surfactants used in detergents are paraffin and α-olefin sulfonates, the latter often called AOS. In general cases, the resulting surfactants are complex mixtures of substances that differ in physicochemical properties. Paraffin sulfonates, or secondary n-alkane sulfonates, are mainly produced in Europe. They are obtained, as a rule, by sulfonic oxidation of paraffin hydrocarbons with sulfur dioxide and oxygen under irradiation with ultraviolet light. In an older process, which is however still in use, paraffin sulfonates are produced by a sulfochlorination reaction. Both processes are radical reactions, and since secondary carbon atoms form more stable free radicals than primary carbon atoms, a sulfo group is introduced statistically to any non-terminal carbon atom of the alkane chain. A mixture of hydrocarbons C 14 -C 17, sometimes called the "Euro-fraction", is the most common hydrophobic raw material, and the final products in this case are represented by very complex mixtures of isomers and homologues.

α-olefin sulfonates are prepared by the reaction of linear α-olefins with sulfur trioxide; the result is a mixture of alkenesulfonates, 3- and 4-hydroxyalkanesulfonates and some disulfonates and other substances. Mainly two olefin fractions are used as feedstock: C 12 -C 16 and C 16 -C 18. The ratio of alkenesulfonates to hydroxyalkanesulfonates is to some extent regulated by the ratio of the amounts of SO 3 and olefins introduced into the reaction mixture: the higher this ratio, the more alkenesulfonic acid is formed. The formation of hydroxyalkane sulfonic acid occurs through an intermediate cyclic sultone, which is then cleaved by alkali. Sutone is toxic, so it is important that its concentration in the final product is very low. The obtaining scheme can be written as follows:

Sodium disulfosuccinate is an alkyl sulfonate surfactant widely used in surface chemistry studies. Due to its bulky hydrophobic group, this surfactant is especially convenient for producing water-in-oil microemulsions.

Isethionate surfactants with the general formula R-COOC^C^SO^Na* are esters of fatty acids and salts of isethionic acid. They are among the mildest surfactants and are used in cosmetic formulations.

Sulfonate surfactants, obtained by sulfonation of lignin, petroleum fractions, alkylnaphthalenes or other cheap hydrocarbon fractions, are widely used industrially as dispersants, emulsifiers, demulsifiers, defoamers, wetting agents, etc.

Sulfonated sulfates and ethoxylated alcohols constitute another important group of anionic surfactants that are widely used in detergents. These are monoesters of sulfuric acid in which the ester bond is very labile and is relatively easily broken at low pH as a result of autocatalytic hydrolysis. Linear and branched alcohols with a number of carbon atoms from 8 to 16 are used as raw materials for this type of surfactant. When using a linear alcohol with 12 carbon atoms, dodecyl ester of sulfuric acid is obtained, and after neutralization with caustic soda, sodium dodecyl sulfate is formed - the most important surfactant of this type. Ethoxylated alcohols, commonly used as intermediates, are aliphatic alcohols with two or three oxyethylene units. The process is similar to the sulfonation discussed above. In industrial production, sulfur trioxide is used as a reagent,

and similar to sulfonation, the reaction proceeds through the stage of formation of pyrosulfate as an intermediate product:

The synthesis of sulfate esters of ethoxylated alcohols is carried out in a similar way. The reaction is usually accompanied by the formation of a noticeable amount of 1,4-dioxane. Since dioxane is toxic, it must be removed by distillation. Such surfactants are usually called ethoxylated alkyl sulfates. They have good foaming properties, low toxicity to the skin and eyes and therefore are used in dishwashing detergents and shampoos.

Ethoxylated alcohols can be converted to carboxylates, i.e. ethoxylated alkyl carboxylates. Traditionally this was done using sodium monochloroacetate:

The Williamson reaction usually proceeds in low yield. Newer synthesis methods are based on the oxidation of ethoxylated alcohols with oxygen or hydrogen peroxide in an alkaline medium using platinum or palladium as a catalyst. In this reaction, conversion of ethoxylates occurs with good yield, but oxidative degradation of the polyoxyethylene chain is also possible. Ethoxylated alkyl carboxylates are used in the manufacture of personal care products or as co-surfactants in various liquid detergent formulations. Like ethoxylated alkyl sulfates, ethoxylated alkyl carboxylates are stable in very hard water. Both types of surfactants also have good ability to disperse calcium soaps, which is very important for surfactants included in personal care products. The ability to disperse calcium soaps is usually expressed as the amount of surfactant required to disperse calcium soap prepared from 100 g of sodium olet in water with a hardness equivalent to 0.0333% CaCO3.

Essential information about anionic surfactants

1. Anionic surfactants are the most common class of surfactants.

2. Typically, anionic surfactants are incompatible with cationic surfactants.

3. They are sensitive to hard water, and sensitivity decreases in the order carboxylates > phosphates > sulfates “sulfonates.

4. The introduction of a short polyoxyethylene chain between the anionic group and the hydrocarbon radical significantly increases the resistance of anionic surfactants to salts.

5. The introduction of a short polyoxypropylene chain between the anionic group and the hydrocarbon radical increases the solubility of the surfactant in organic media, but at the same time can lead to a decrease in the rate of biodegradation of the surfactant.

6. As a result of autocatalytic hydrolysis, sulfate surfactants quickly hydrolyze in acidic environments. Other types of surfactants are stable under not too harsh conditions.

All commercial phosphate surfactants contain phosphoric acid mono- and diesters, and the relative content of these components varies widely depending on the manufacturer. Since the physicochemical properties of alkyl phosphate surfactants depend on the ratio of different esters, alkyl phosphates from different manufacturers are less interchangeable than other types of surfactants. Phosphorus oxychloride POCI 3 can be used as a phosphorylating agent for the production of alkyl phosphate surfactants. In this case, a mixture of mono- and diesters of phosphoric acid is also formed.