Needs National economy in surfactants are huge. Their production around the world is increasing every year. From what raw materials are huge amounts of various surfactants obtained?

We have already said that until the mid-1960s, mainly natural (natural) surfactants were used. The main volume of surfactants was obtained by relatively simple processing of limited raw materials of animal and, less often, vegetable origin. Some of these substances, which have proven themselves in industry and in everyday life, have not lost their significance even now. This is explained not only by high efficiency their actions, but also to a large extent low cost.

Food-derived surfactants are mentioned in various sections of the book.

Nonsulfonated compounds - no more than 3; sodium sulfates and sulfites - no more than 15. Sulfanol is available in two forms - liquid (active substance content of at least 45%) and powder (100% active substance).

Azolates (A, B, A-2) - a mixture of sodium salts of alkyl benzene sulfonic acids. It is obtained from kerosene-gas oil fractions of oil in the form of pastes that are readily soluble in water. Medium molecular mass 300-350, active substances 50-70%, water 20-35%; belong to "biologically soft Kim" surfactant. Biodegradability in wastewater at an initial surfactant concentration of 20 and 10 mg/l is 85 and 95%, respectively. The surface activity of isolates is quite high: the surface tension for isolate A and isolate B is 31.2 and 35.6 N/m at a concentration of 0.1%, respectively, and at a concentration of 0.5% - 27.9 and 30.0 N/m.

Calcium salts of alkylarylsulfonic acids - high molecular weight alkylarylsulfonate. Obtained from reflux condensation products catalytic cracking and cracked kerosene followed by sulfonation and neutralization. The average molecular weight is from 40 to 500. The content of active substances is 14-15%, water is up to 80%. Significantly reduces the surface tension of water (up to 37 N / m) already at a concentration in the solution of 0.25%. Gives high expansion and stable foam. Effective in cement materials, clay suspensions.

Disodium salts of sulfocarboxylic acids-mixture Macromolecular acids with more than 18 carbon atoms. General formula

R - CH - COONa I

Biodegradability in wastewater reaches 90-95%. They get cheap and scarce raw materials using a simple technology, which makes disodium salts of sulfocarboxylic acids promising surfactants for producing medium expansion foams.

Necal Blend sodium salts of mono-, di- and triiso-butylnaphthalenesulfonic acids. Mainly composed of dialkyl derivatives

(iso-C4H 9) 2C 10H 5SO 3Na

The polar group is SO 3Na. The non-polar part is cyclic and aliphatic hydrocarbon radicals. Po)
In appearance, it is a non-separating paste, which contains 20-40% moisture.

Sodium lauryl sulfate - the general formula is R0S03Na, i de R = C9-C15. This is the cheapest foaming agent. Note that potassium lauryl sulfates give peyu of a higher multiplicity (almost three times) compared to sodium salts. Parkistic application is found Also products of neutralization of trieth lauryl sulfate with nolamine.

Oxyethylated sodium lauryl sulfate- Condensation product of ethylene oxide and C,2-Cm fatty alcohols, followed by treatment with chlorosulfonic acid and neutralization with NaOH. It has been established that with an increase in the number of carbon atoms in an alcohol molecule, the solubility in an alkaline medium decreases; Of greatest practical interest are more accessible alcohols with an odd number of carbon atoms in the molecule (C, -C15).

Foam concentrates PO-1 and PO-1A - liquids from yellow to brown, without sediment and foreign inclusions.

PO-1 is obtained by neutralizing the kerosene contact. Contains at least 45% sula | yukislot. To ensure high expansion and stability of the foam, 3.5-5.5% bone glue and 10% ethyl alcohol or ethylene glycol are added to the composition.

PO-1 A is a mixture of sodium alkyl sulfates based on sulfuric acid esters of secondary alcohols with the number of carbon atoms in the alkyl radical from 8 to 18. The content of the active substance is not less than 20%.

These foam concentrates are designed to produce fire-fighting foam. When using high-expansion foam generators (fire trucks are equipped with such installations) from 2-5% aqueous solutions

4-111
these foaming agents produce stable foam with a multiplicity of 70-150. Such foam extinguishes burning oil products well.

Substance to Progress» - a mixture of sodium salts of sulfate esters of secondary alcohols with a carbon number in alkyl radicals from 6 to 16. Serves as a detergent in a number of synthetic detergents produced by the domestic industry.

Salts of alkylamines and salts of tetrasubstituted Ammo Nyl-these cationic substances are obtained on the basis of | amines of various degrees of substitution, quaternary ammonium-1 and other nitrogen-containing bases (hydrazines, guanidine, heterocyclic compounds).

RNHT - HCI- hydrochloride salt of alkylamine, where I R is a hydrocarbon radical from Сі0Н2і to С20Н41;

RR"R"R""NCI-coflb of tetrasubstituted ammonium,! where R is a long hydrocarbon radical with 12-18 carbon atoms, and R"R"R"" are short hydrocarbon radicals (CH3 or C2H5).

OP-7, OP-Yu, sintanol DS-10- Substances of non-ionic type. All of them are products of the interaction of phenol, al - kylphenols OR HIGHER FATTY ALCOHOLS With yu Cjg with HE-1 how many moles of ethylene oxide according to the reaction

ROH + nH2q-CH2 R(OCH2CH2)/JOH

Where R is a hydrocarbon radical from C10H21 to C20H41.

Silicone compounds - are characterized by high surface activity, some of them can be used as foaming agents in the production of waterproof materials. The most widespread
Valuable compounds of this class in domestic practice are ethnlchlorosilanes (GKZH-94), methyl and ethyl silconates (GKZH-10 and GKZH-11).

The development of new synthetic surfactants is carried out in more than ten academic and industrial research institutes of the country. Surfactants are created with a set of specially specified properties, which, in addition to high foaming ability, should have low toxicity and weak physiological activity, high biodegradability, and many other properties important for practice.

Doctor of technical sciences V.A. Ryzhenkov, Ph.D. A.V. Kurshakov, A.V. Ryzhenkov, engineer,
Moscow Power Engineering Institute (Technical University);
Ph.D. I.P. Pulner, chief engineer,
Ph.D. S.N. Shcherbakov, director of branch No. 7 "South-West",
JSC "Moscow United Energy Company", Moscow

Introduction

The most pressing modern problems in the domestic heat and power industry, including urban heat supply systems, are currently improving the reliability, durability and energy efficiency of heat networks, generating and heat exchange equipment, shut-off and control valves and pipelines. As part of this, such tasks are solved as increasing the corrosion resistance of structural materials, reducing the rate of formation of new and effectively removing existing thermal barrier deposits from heat exchange surfaces, reducing hydraulic losses during coolant transportation, reducing costs during maintenance and preventive maintenance, and a number of other tasks.

One of the promising ways of an integrated approach to solving the above problems is the application of the developed in the Moscow energy institute(Technical University) Surfactant technologies based on the conditioning of the coolant with molecules of surface-active substances (surfactants).

The use of surfactant technologies in thermal power engineering

In world practice, there are many examples of the use of surfactants as highly effective corrosion inhibitors. It suffices to note that in Russian Federation today there are regulations (guiding documents - RD) for protection against parking (atmospheric) corrosion of thermal power equipment of thermal power plants and heating networks (RAO "UES of Russia"), as well as nuclear power plants with VVER (Rosatom) using surfactants from the class of film-forming amines.

It is known that the use of surfactants in the heat networks of a number of countries has made it possible to radically solve the problem of increasing the reliability and service life of heat engineering equipment based on almost complete blocking corrosion processes.

In recent years in scientific center"Wear resistance" MPEI (TU) for the first time it was found that conditioning the coolant with surfactant molecules leads to an increase in the internal relative efficiency of centrifugal pumps up to 4%, a decrease in the hydraulic resistance of the main and distributing pipelines by 25-30%. These effects are associated with the formation on metal surfaces of densely packed, strictly oriented layers of surfactant molecules, which, due to the “smoothing” of their roughness, reduce the degree of flow turbulence in the near-wall layers of the flow.

The presented article presents the results of applying one of the variants of SAW technology in the urban heat supply system on the example of an autonomous section of heating networks of one of the quarterly thermal stations (KTS) of Branch No. heating season 2006-2007

Autonomous section of the heat supply system includes a hot water boiler PTVM-50, two boilers KVGM-20, with a total capacity of 90 kcal / h, main heating mains and inputs with pipelines different diameter(80-500 mm), as well as distribution pipelines and heating systems for buildings and structures with a total volume of 2141 m3. The heat supply scheme of the consumer stations connected to the heating networks is a closed two-pipe. Water with a temperature curve of 150-70 °C is used as a heat carrier.

The implementation of SAW technology was carried out using a specially designed mobile unit, general form which is shown in Fig. 1. The main purpose of this installation is to provide conditioning of the coolant with the molecules of the surfactant used according to a special technological procedure. The duration of the conditioning of the coolant with surfactant molecules is determined by the length and branching of the autonomous section, as well as by the uneven intensity of the recharge.

The conditioning process ends after reaching the calculated concentrations of surfactant molecules in the coolant in various points schemes (within the KTS, as well as at the central heating station and ITP).

In the process of implementing the surfactant technology, it was possible to ensure a sufficiently effective sorption of surfactant molecules on the inner surfaces of pipelines and heating equipment and form strictly oriented, ordered molecular layers on them, which are a guaranteed barrier to the access of oxygen and carbon dioxide molecules to the metal.

It is known that in the process of moving to the metal surface, surfactant molecules due to their increased activity contribute to loosening and flaking of deposits and corrosion products, which, as a rule, are present on the functional surfaces of heat supply equipment. This circumstance was recorded during the implementation of SAW technology in a selected autonomous section of the heat supply system. As an illustration, in fig. Figure 2 shows the distribution of iron concentrations within the CTS for the period from March 13, 2007 to March 21, 2007. Coolant samples were taken from sampling points located directly behind the boiler. The total amount of iron removed (in terms of Fe2O3) from the screens and convective bundles of only one PTVM-50 boiler was more than 60 kg.

At the same time, local “bursts” of chloride concentrations in the coolant were recorded. In the supplied network water, the maximum concentration of chlorides reached 2.0 mg-eq/kg, in the return water - up to 0.5 mg-eq/kg, which indicates the desorption of chloride ions accumulated during operation from microcracks, pores and caverns of the surface layer of the metal.

The pH value of the network water (both in the forward and return pipelines) remained practically unchanged during the entire monitoring period. The measured values ​​are in the range of 8.89-9.08.

As mentioned above, the formation internal surfaces pipelines of surfactant molecular layers should lead to a change in the coolant flow regime. To determine the effect of surface molecular layers of surfactants on velocity diagrams in pipelines of heating networks, a special probe was developed, the scheme of which is shown in Fig. 3. The principle of operation of the probe is based on measuring the dynamic pressure of the flow at different distances from the pipeline wall by successively switching Pitot tubes. The dynamic pressure was recorded by a differential pressure gauge DSP-160M1, to one input of which a collector of Pitot tubes was connected, and to the other - a static pressure tube.

The probe was installed in the central heating station on a pressure pipeline with a diameter of 125 mm in compliance with all conditions to minimize the measurement error associated with unsteady flow.

On fig. Figure 4 shows the velocity profiles recorded on January 22, 2007 (before conditioning the coolant with surfactant molecules) and March 15, 2007, on the days when the outdoor air temperature and direct network water flow rates at the CTS at the time of measurements coincided at t=+3 °C and G=810 t/h (see curves 1 and 2). In the same figure, for comparison, classic profile flow velocities in a perfectly smooth pipe. The analysis shown in fig. 4 flow profiles shows what value average speed in the process of conditioning the coolant with surfactant molecules increased by 7.4%, naturally this will lead to an adequate change in the flow of the coolant.

In order to determine the change in pressure drops during conditioning of the coolant with surfactant molecules, reference pressure gauges (class 0.15) were installed at the inlet and outlet of heating points with dependent (TsTP1T) and independent (TsTP2T) connection schemes. As well as when measuring local velocities, the dates (January 22, 2007 and March 15, 07) were chosen for comparison with the same outside air temperatures, with the flow rate of network water supplied to the CTS. Pressure measurements at the TsTP1T were carried out with a fully open shut-off and adjustable valve. A steady decrease in pressure drop was recorded from 0.3333 MPa to 0.3291 MPa, i.e. by ~1.3%. Accordingly, at TsTP2T, the pressure drop across the boiler decreased from 0.3289 MPa to 0.3177 MPa, i.e. by ~3.5%.

The removal of deposits from the functional surfaces of pipelines and heat engineering equipment, as well as their hydrophobization and a corresponding increase in the efficiency of network pumps, led to a change in the rotational speed of their rotors. On fig. Figure 5 shows the distribution of rotation frequencies of the rotors of network pumps for the period from 22.01.07 to 22.03.07.

The spread of frequency drops reached 5.2 Hz. This nature of the curves is due to the fact that the regulation of the operating mode of the KTS boilers both with the help of recirculation pumps (recirculation valves) and by mixing part of the return network water into the supply line through the jumper valve was provided manually by the operator on duty, and the electric drive of the network pumps with frequency-regulating the converter is set to a fixed pressure in the supply pipeline of the heating network at the outlet of the CTS.

Presented in fig. The results shown in Fig. 5 show that the rotational speeds of the rotors of network pumps during the conditioning of the coolant with surfactant molecules in the period from 01/22/07 to 03/22/07 decreased from 41.1 to 39.2 Hz, i.e. by 4.75%.

For two continuously operating network pumps with a total electric power of 630 kW (2x315 kW), the energy savings in this case can be ~153 thousand kWh with medium duration the heating period in Moscow is 213 days.

Undoubtedly, from a practical point of view, the specific indicator q, calculated as the ratio of the fuel used in the hot water boiler (boilers) (in this case of gas - thousand m3) to the amount of heat (Gcal) supplied to the consumer (to all central heating stations). Monitoring of these indicators at the CTS is carried out automatically with an hourly frequency of their registration.

| free download On improving the efficiency of operation of urban heat supply systems based on SAW technologies, Ryzhenkov V.A., Kurshakov A.V., Ryzhenkov A.V., Pulner I.P., Shcherbakov S.N.,

Nonionic surfactants

Compounds that dissolve in water without forming ions are called non-ionic. Their group is represented by polyglycol and polyglycol esters of fatty alcohols (for example, facestenside - Disodium Laurethsulfosuccinate - a fluid liquid consisting of citric acid and fatty alcohols). Non-ionic surfactants are obtained by oxyethylation of vegetable oils (castor, wheat germ, flax, sesame, cocoa, calendula, parsley, rice, St. John's wort). Non-ionic surfactants exist only in liquid or paste form, therefore they cannot be contained in solid detergents (soaps, powders).

Aqueous solutions esters fatty acids are a dispersion micellar solution often referred to as "smart soap" because it emulsifies dirt and grease, removing them from the surface of the skin and hair without damaging the protective mantle.

Properties of non-ionic surfactants

This type of surfactant makes the detergent soft, safe, environmentally friendly (biodegradability of non-ionic tensides is 100%). They stabilize soap suds, have mild thickening properties, have a bradykinase and polishing effect, restoring the outer layers of the epidermis and hair, and help to activate the action of therapeutic additives of the cleansing preparation.

This is the most promising and rapidly developing class of surfactants. At least 80-90% of these surfactants are obtained by adding ethylene oxide to alcohols, alkylphenols, carboxylic acids, amines, and other compounds with reactive hydrogen atoms. Polyoxyethylene ethers of alkylphenols are the most numerous and widespread group of nonionic surfactants, including more than a hundred trade names, the most well-known preparations are OP-4, OP-7 and OP-10. Typical raw materials are octyl-, ionyl- and dodecylphenols; cr. In addition, cresols, cresol acid, β-naphthol, etc. are used. If an individual alkylphenol is taken into the reaction, the finished product is a mixture of surfactants of the total f-ly RC6H4O (CH2O) mH, where m is the degree of oxyethylation, depending on the molar ratio of the initial components.

All surfactants. can be divided into two categories according to the type of systems they form when interacting with a dissolving medium. One category includes micelle-forming surfactants. in., to the other - not forming micelles. In solutions of micelle-forming surfactants c. above the critical micelle concentration (CMC), colloidal particles (micelles) appear, consisting of tens or hundreds of molecules (ions). Micelles reversibly decompose into individual molecules or ions upon dilution of a solution (more precisely, a colloidal dispersion) to a concentration below the CMC.

Thus, solutions of micelle-forming surfactants. occupy an intermediate position between true (molecular) and colloidal solutions, therefore they are often called semi-colloidal systems. Micellar surfactants include all detergents, emulsifiers, wetting agents, dispersants, etc.

It is convenient to estimate surface activity by the largest decrease surface tension divided by the corresponding concentration - CMC in the case of micelle-forming surfactants. Surface activity is inversely proportional to CMC:

The formation of micelles occurs in a narrow range of concentrations, which becomes narrower and more defined as the hydrophobic radicals lengthen.

The simplest micelles of typical semi-colloidal surfactants, for example. salts fatty to-t, at concentrations not too much higher than the CMC, have a spheroidal shape.

An increase in the concentration of surfactants in anisometric micelles is accompanied by a sharp increase in the structural viscosity, leading in some cases to gelation, i.e. complete loss of fluidity.

action of detergents. Soap has been known for thousands of years, but it is only relatively recently that chemists have understood why it has detergent properties. The dirt removal mechanism is essentially the same for soap and synthetic detergents. Let's take it as an example of table salt, conventional soap, and sodium alkylbenzenesulfonate, one of the first synthetic detergents.

When dissolved in water salt dissociates into positively charged sodium ions and negatively charged chloride ions. Soap, i.e. sodium stearate (I), substances similar to it, as well as sodium alkylbenzenesulfonate (II) behave in a similar way: they form positively charged sodium ions, but their negative ions, unlike the chloride ion, consist of about fifty atoms.

Soap (I) can be represented by the formula Na+ and C17H35COO-, where 17 carbon atoms with hydrogen atoms attached to them are stretched out in a winding chain. Sodium alkylbenzenesulfonate (Na+ C12H25C6H4SO3-) has about the same number of carbon and hydrogen atoms. However, they are not located in the form of a winding chain, as in soap, but in the form of a branched structure. The significance of this difference will become clear later. For washing action the important thing is that the hydrocarbon part of the negative ion is insoluble in water. However, it is soluble in fats and oils, and it is thanks to fat that dirt sticks to things; and if the surface is completely free of grease, dirt does not linger on it.

The negative ions (anions) of soap and alkylbenzenesulfonate tend to concentrate at the interface between water and fat. The water soluble negative end remains in the water while the hydrocarbon portion is immersed in the fat. In order for the interface to be the largest, the fat must be present in the form of tiny droplets. As a result, an emulsion is formed - a suspension of droplets of fat (oil) in water (III).

If there is a film of fat on a solid surface, then upon contact with water containing detergent, the fat leaves the surface and passes into the water in the form of tiny droplets. Soap and alkylbenzenesulfonate anions are at one end in water and at the other end in fat. Dirt held by a film of grease is removed by rinsing. So in a simplified form, you can imagine the action of detergents.

Any substance that tends to collect at an oil-water interface is called a surfactant. All surfactants are emulsifiers because they promote the formation of an oil-in-water emulsion, i.e. "mixing" oil and water; all of them have detergent properties and form foam - after all, foam is like an emulsion of air bubbles in water. But not all of these properties are expressed in the same way. There are surfactants that lather profusely but are weak detergents; there are also those that almost do not foam, but are excellent detergents. Synthetic detergents are synthetic surfactants with particularly high detergency. In the industry, the term "synthetic detergent" generally means a composition including a surfactant, bleaches and other additives.

Soaps, alkylbenzenesulfonates and many other detergents, where exactly the anion dissolves in fats, are called anionic. There are also surfactants in which the cation is fat-soluble. They are called cationic. A typical cationic detergent, alkyldimethylbenzylammonium (IV) chloride is a quaternary ammonium salt containing nitrogen bonded to four groups. The chloride anion always remains in water, which is why it is called hydrophilic; hydrocarbon groups associated with a positively charged nitrogen are lipophilic. One of these groups, C14H29, is similar to the long hydrocarbon chain in soap and alkylbenzenesulfonate, but it is attached to positive ion. Such substances are called "reverse soaps". Some of the cationic detergents have strong antimicrobial activity; they are used as part of detergents intended not only for washing, but also for disinfection. However, if they cause eye irritation, then when they are used in aerosol formulations, this circumstance should be reflected in the instructions on the label.

Another type of detergent is non-ionic detergents. The fat-soluble group in the detergent (V) is something like the fat-soluble groups in alkylbenzenesulfonates and soaps, and the remainder is a long chain containing many oxygen atoms and an OH group at the end, which are hydrophilic. Typically, non-ionic synthetic detergents exhibit high detergency but low lather.

surfactants (Synthetic Surfactants) are large group compounds that are different in structure, belonging to different classes. These substances are able to be adsorbed on the phase interface and consequently lower the surface energy (surface tension). Depending on the properties exhibited by surfactants when dissolved in water, they are divided into anionic substances (the active part is the anion), cationic (the active part of the molecules is the cation), ampholytic and non-ionic, which are not ionized at all.

It is no secret that the main active ingredients of washing powders are surface-active substances (surfactants). In truth, these active chemical compounds, when they enter the body, destroy living cells by disrupting the most important biochemical processes.

The future of synthetics? Apparently yes. In confirmation of this, surfactants are being improved more and more, there are so-called non-ionic surfactants, the biodegradability of which reaches 100%. They are more efficient at low temperatures, which is important for gentle washing modes. Since many artificial fibers can't stand high temperatures. In addition, washing in more cold water saves energy resources, which is more relevant every day. Unfortunately, most non-ionic surfactants are liquid or pasty and are therefore used in liquid and pasty detergents. In powdered SMS, nonionic surfactants are introduced in the form of additives of 2-6% wt. Important advantages of synthetic surfactants are that they do not form calcium and magnesium salts that are poorly soluble in water. This means that they wash equally well in both soft and hard water. The concentration of synthetic detergents, even in soft water, can be much lower than soaps made from natural fats.

Probably, from household chemicals, we know the most synthetic detergents. In 1970, for the first time in the world, synthetic detergents (SMC) were produced more than ordinary natural soap. Every year its production is decreasing, while the production of SMS is continuously increasing.

For example, in our country, the dynamics of growth in the production of SMS can be displayed by the following data: in 1965 they were produced 106 thousand tons, in 1970 - 470 thousand tons, and in 1975 almost one million tons will be produced.

Why is the production of natural, sound soap, which faithfully served a person for many years, falling so much? It turns out he has a lot of flaws.

Firstly, soap, being a salt of a weak organic acid (more precisely, a salt formed by a mixture of three acids - palmitic, margaric and stearic) and a strong base - caustic soda, hydrolyzes in water: Xia (i.e., it is split by it) into acid and alkali. The acid reacts with hardness salts and forms new salts, already insoluble in water, which fall out in the form of a sticky white mass on clothes, hair, etc. This not very pleasant phenomenon is well known to anyone who has tried washing or bathing in hard water.

Another product of hydrolysis - alkali - destroys the skin (degreases it, leads to dryness and the formation of painful cracks) and reduces the strength of the fibers that make up various tissues. Polyamide fibers (kapron, nylon, perlon). are destroyed by soap especially intensively.

Secondly, soap is a relatively expensive product, since its production requires food raw materials - vegetable or animal fats.

There are other, less significant shortcomings of this until recently, completely indispensable substance in everyday life.

Unlike natural soaps, synthetic detergents have undoubted advantages: greater washing power, hygiene and economy.

About 500 names of synthetic detergents are now known on the international market, produced in the form of powders, granules, flakes, pastes, liquids.

The production of SMS gives a great economic effect. Experiments have shown that one ton of synthetic detergents replaces 1.8 tons of 40% laundry soap made from valuable food raw materials. It is estimated that one ton of SMS saves for Food Industry 750 kg of vegetable fats.

The use of SMS in household allows you to reduce labor costs for hand and machine washing by 15-20% * At the same time, the strength and initial consumer properties of the fabric (whiteness, color brightness, elasticity) are much better than when using ordinary laundry soap.

It must be said that SMS is intended not only for washing clothes. There are special products for washing and cleaning various household items, synthetic toilet soaps, hair washing shampoos, foaming bath additives, into which biostimulants are introduced that have a tonic effect on the body.

The main component of all these products is a synthetic surfactant, the role of which is the same as that of an organic salt in ordinary soap.

However, chemists have long known that an individual substance, no matter how universal it may be, cannot satisfy all the requirements placed on it. Small additions of other accompanying substances help to find very useful qualities in this basic substance. That is why all modern SMS are not individual surfactants, but compositions that may include bleaches, fragrances, foam regulators, biologically active substances and other components.

The second most important component of modern synthetic detergents are condensed, or polymeric, phosphates (polyphosphates). These substances have a number of useful properties: they form water-soluble complexes with metal ions present in water, which prevents the appearance of insoluble mineral salts that occur when washing with ordinary soap; increase the detergent activity of surfactants; prevent sedimentation of suspended particles of dirt on the washed surface; cheap to manufacture.

All these properties of polyphosphates make it possible to reduce the content of the more expensive main component, surfactant, in SMS.

As a rule, any synthetic detergent includes a fragrance - a substance with a pleasant smell, which is transferred to the laundry when using SMS.

Almost all SMS are injected with a substance called sodium salt carboxymethyl cellulose. It is a high molecular weight synthetic product, soluble in water. Its main purpose is to be, along with phosphates, an antiresorptive, i.e. prevent dirt from settling on already washed fibers.

Most of them have a number of advantages over soap, which has long been used for this purpose. So, for example, surfactants dissolve well and foam even in hard water. The potassium and magnesium salts formed in hard water do not worsen the washing action of surfactants and do not form a white coating on the hair.

Main active substances all washing powders, so-called. Surfactants (surfactants) are extremely active chemical compounds. Possessing some chemical affinity with certain components of human and animal cell membranes, surfactants, when ingested, accumulate on cell membranes ah, covering their surface with a thin layer and at a certain concentration can cause violations of the most important biochemical processes occurring in them, disrupt the function and integrity of the cell itself.

In experiments on animals, scientists have found that surfactants significantly change the intensity of redox reactions, affect the activity of a number of important enzymes, and disrupt protein, carbohydrate and fat metabolism. Surfactant anions are especially aggressive in their actions. They can cause gross violations of the immune system, the development of allergies, damage to the brain, liver, kidneys, and lungs. This is one of the reasons why countries Western Europe imposed strict restrictions on the use of a-surfactants (anionic surfactants) in the composition of washing powders. AT best case their content should not exceed 2-7%. In the West, more than 10 years ago, they abandoned the use of powders containing phosphate additives in everyday life. In the German, Italian, Austrian, Dutch and Norwegian markets, only phosphate-free detergents are sold. In Germany, the use of phosphate powders is prohibited. federal law. In other countries, such as France, Great Britain, Spain, in accordance with government decisions, the content of phosphates in SMS is strictly regulated (no more than 12%).

The presence of phosphate additives in powders leads to a significant increase in the toxic properties of a-surfactants. On the one hand, these additives create conditions for a more intense penetration of a-surfactants through intact skin, promote enhanced degreasing. skin, more active destruction of cell membranes, sharply reduce the barrier function of the skin. Surfactants penetrate into the microvessels of the skin, are absorbed into the blood and distributed throughout the body. This leads to a change physical and chemical properties the blood itself and impaired immunity. A-surfactants have the ability to accumulate in organs. For example, 1.9% of the total amount of a-surfactants that got on unprotected skin settles in the brain, 0.6% in the liver, etc. They act like poisons: in the lungs they cause hyperemia, emphysema, in the liver they damage the function of cells, which leads to an increase in cholesterol and intensifies the phenomena of atherosclerosis in the vessels of the heart and brain, disrupts the transmission nerve impulses in the central and peripheral nervous systems.

But this does not exhaust the harmful effects of phosphates - they are a great threat to our environment. Getting after washing along with sewage into water bodies, phosphates are taken to act as fertilizers. The "harvest" of algae in reservoirs begins to grow by leaps and bounds. Algae, decomposing, secrete into huge quantities methane, ammonia, hydrogen sulfide, which destroy all life in the water. Overgrowth of reservoirs and clogging slowly flowing waters leads to gross violations of ecosystems of water bodies, deterioration oxygen exchange in the hydrosphere and create difficulties in providing the population drinking water. It is also for this reason that many countries have legally banned the use of phosphate SMS.

The traditional disadvantage of surfactants is harshness, expressed in skin irritation, dryness and discomfort after using shampoo or shower gel.

The skin of the hands, in contact with active chemical solutions washing powders, become the main conductor of the penetration of hazardous chemical agents into the human body. A-surfactants actively penetrate even through intact skin of the hands and, with the assistance of phosphates, enzymes and chlorine, intensively disinfect it. Restoration of normal fat content and moisture of the skin occurs no earlier than after 3-4 hours, and with repeated use due to the accumulation of the harmful effect, the lack of fatty skin coating is felt within two days. barrier functions of the skin are reduced, and conditions are created for intensive penetration into the body of not only a-surfactants, but also any toxic compounds - bacteriological toxins, heavy metals etc. After several washes with phosphate powders, skin inflammations - dermatitis - often develop. The pipeline of pathological immune reactions is launched.

In 1917, the American I. Langmuir discovered that some substances very actively accumulate on various boundary surfaces (at the air-water, water-oil borders). The accumulation occurs because the surface of any body has an uncompensated reserve free energy arising because the molecules solid body or liquids are attracted to each other with a force many tens of times greater than air molecules. As a result, a layer of molecules appears at the solid-air boundary, the forces of attraction of which are not compensated. This is the reason for the excess of free energy and surface tension at the solid-air interface.

Adding various chemical nature substances leads to an increase or decrease in the surface tension of aqueous solutions. Substances that increase surface tension are called surface-inactive (PIAV) ; lowering - surface-active (surfactant) . PIAs include, for example, any electrolytes (alkalis, acids). Surfactants are most often bipolar organic compounds, the nonpolar (hydrophobic) part of which is represented by a long-chain hydrocarbon radical with C › 8, the polar (hydrophilic) part is represented by various functional groups.

When a surfactant comes into contact with the surface of a liquid or solid, a process occurs adsorption , which consists in the accumulation of molecules surfactant substances at the interface. A feature of adsorption is that it proceeds with the release of heat, and not on the entire surface of a solid, but only on its active centers. The adsorption layer may consist of one or more layers of adsorbed molecules. A feature of the surface of a liquid is that all its points are equally active in adsorption. The hydrophilic group of the surfactant goes to the water, and the hydrophobic group goes to the air. This orientation of the molecules Langmuir called the "palisade". As a result, the properties of bodies covered with adsorption layers change dramatically: hydrophobic surfaces become more hydrophilic and are better wetted by water.

During adsorption, the dissolution of the surfactant in one of the phases also occurs. In this case, true solutions are first formed, in which surfactants are in the form of molecules. As the surfactant is added, abrupt change properties of solutions. There is a formation colloidal solutions, in which surfactants are in the form of larger aggregates called micelles. The limit of true surfactant solubility is called the critical micelle concentration (CMC).

Most universal methods definitions of KKM are:

1) calculation from surface tension isotherms of surfactant solutions;

2) potentiometric titration of surfactant solutions;

3) temperature method (according to the Kraft point of surfactant solutions).

The ability of a surfactant during adsorption on a phase interface to radically change its properties and thereby affect many important indicators dispersed systems is widely used in the most various areas technology and numerous technological processes. In this case, the influence of surfactants can be different depending on the chemical nature and structure of the adjacent phases and surfactant molecules, as well as on the conditions of their application. According to Rehbinder, four groups of surfactants can be distinguished:

a) in physics chemical mechanism their impact on the interface and the dispersed system as a whole:

· substances that are surfactant only (or predominantly) at the water-air interface.

Surfactants belonging to this group are moderately effective wetting agents and foaming agents. Some representatives (octanol, isoamyl alcohol) can act as defoamers;

· Substances of diverse nature, surface-active at various interfaces of condensed phases. Surfactants of this group most often act as dispersants; in addition, they allow you to control the electoral m;

· Surfactants that have the ability to form gel-like structures in adsorption layers and in phase volumes.

As a rule, these are high-molecular surfactants (proteins, glycosides, cellulose derivatives, etc.). Such substances are used as highly effective stabilizers of moderately concentrated dispersed systems different nature: foams, emulsions, suspensions. Surfactants of this group can act as plasticizers of highly concentrated dispersions;

· Surfactants with detergent action.

They combine the functions of surfactants of the rest three groups and, in addition, are capable of education in volume liquid phase thermodynamically stable colloidal particles - micelles and the inclusion of washed impurities in the core of micelles - solubilization . Important quantitative characteristic surfactant is hydrophilic - lipophilic balance (HLB) G Riffin - Davis. The HLB numbers characterize the ratio between hydrophilic and hydrophobic properties: the higher the HLB number, the more the balance is shifted towards the polar (hydrophilic) properties of the surfactant. The HLB numbers are determined experimentally. The works of Davis established the quantitative dependence of HLB on the composition and structure of surfactants. Each structural unit contributes to the HLB number. Griffin's GLB numbers are:

o for hydrophilic groups: -COOK - 21.1, -COONa - 19.1, -COOH - 2.4, -OH - 1.9, =O - 1.3, -SO3K - 38.7, -SO3H - 3.8;

o hydrophobic: =CH-, -CH2-, -CH3, =C=C- -0.475; o = -1.25

Based on these data, HLB numbers can be calculated using the formula:

Where Σ(HLB H.FIL.) and Σ(HLB H.FOB.) is the sum of the HLB numbers of all hydrophilic and hydrophobic groups, respectively.

The physical meaning of HLB numbers is that they determine the work of adsorption during the transfer of polar groups of surfactant molecules to the nonpolar phase and nonpolar groups to the polar one. Depending on the number of HLB surfactants are used for a particular purpose. So, if surfactants have HLB numbers from 7 to 9, they are used as wetting agents, from 13 to 15 - as detergents, from 15 to 18 - as solubilizers in aqueous solutions;

b) on chemical structure Surfactants are divided into two large classes.

On the one hand, these are organic surfactants with amphiphilic molecules, universally surface-active at most interphase boundaries, but providing only a slight (by 30–40 mJ/m 2) decrease in surface tension. On the other hand, these are the most diverse, primarily inorganic substances, exhibiting selective, but often very high surface activity in relation to this particular interface, capable of causing a very sharp decrease in surface tension (for example, sodium phosphates in aqueous systems);

c) by type of raw material, used for synthesis, surfactants are divided into natural and synthetic;

d) by chemical nature and charge sign, acquired by the surface during adsorption, surfactants are classified into anionic, cationic, nonionic, amphoteric.