Soap chemical composition and properties. Chemistry of soap and detergents. Soap without soap

07.09.2023

General information on the raw materials from which soap is made.

Animal fats – an ancient and valuable raw material for soap-making surfaces. They contain up to 40% saturated fatty acids. Artificial, that is, synthetic, fatty acids are obtained from petroleum paraffin by catalytic oxidation with atmospheric oxygen. During oxidation, the paraffin molecule is broken in different places, and a mixture of acids is obtained, which are then separated into fractions. In the production of soap, mainly two fractions are used: C 10 -C 16 and C 17 -C 20. Synthetic acids are introduced into laundry soap in an amount of 35-40%.

Also used for soap production naphthenic acids released during the purification of petroleum products(gasoline, kerosene, etc.). for this purpose, petroleum products are treated with a solution of sodium hydroxide and an aqueous solution of sodium salts of naphthenic acids (monocarboxylic acids of the cyclopentane and cyclohexane series) is obtained. This solution is evaporated and treated with table salt, as a result of which a dark-colored, ointment-like mass, soap naft, floats to the surface of the solution. To purify soap naphtha, it is treated with sulfuric acid, that is, the naphthenic acids themselves are displaced from the salts. This water-insoluble product is called asidol, or asidolmylonaft. Only liquid or soft soap can be made directly from asidol. It has an oily smell, but it has bactericidal properties.

It has long been used in soap production rosin, which is obtained by processing the resin of coniferous trees. Rosin consists of a mixture of resin acids containing about 20 carbon atoms in the carbon chain. 12-15% of rosin by weight of fatty acids is usually added to the composition of laundry soap, and no more than 10% is added to the formulation of toilet soaps. The introduction of rosin in large quantities makes the soap soft and sticky.

Of course, today it is important to use a variety of vegetable fats, there is a separate article about them in the section.

In addition to using soap as a detergent, it is used in bleaching fabrics, in the production of cosmetics, and for the manufacture of polishing compounds for water-based paints.

In everyday life, various items and objects are subjected to the washing process. Pollutants come in a wide variety of forms, but most often they are poorly soluble or insoluble in water. Such substances, as a rule, are hydrophobic, since they are not wetted by water and do not interact with water. Therefore, various detergents are needed.

Washing can be called cleaning a contaminated surface with a liquid containing a detergent or a system of detergents. Water is mainly used as a liquid in everyday life. A good cleaning system should perform a dual function: remove dirt from the surface being cleaned and transfer it into an aqueous solution. This means that the detergent must also have a dual function: the ability to interact with the pollutant and the ability to transfer it into water or an aqueous solution.

Therefore, a detergent molecule must have hydrophobic and hydrophilic parts. "Phobos" in Greek means fear. Fear. So hydrophobic means “afraid of, avoiding water.” “Phileo” in Greek means “love”, hydrophilic means loving. Water retaining.

The hydrophobic part of the detergent molecule has the ability to interact with the surface of the hydrophobic contaminant. The hydrophilic portion of the detergent interacts with the water, penetrates the water, and carries with it the contaminant particle attached to the hydrophobic end.

Detergents must have the ability to be adsorbed on the boundary surface, that is, they must have surfactants.

Salts of heavy carboxylic acids, for example CH 3 (CH 2) 14 COONa, are typical surfactants. They contain a hydrophilic part (in this case, a carboxyl group) and a hydrophobic part (hydrocarbon radical).

Properties of soaps. What is soap?

Soaps are salts of high molecular fatty acids. In technology, soaps are sodium or potassium salts of higher fatty acids, the molecules of which contain at least 8 and no more than 20 carbon atoms, as well as similar naphthenic and resin acids (rosin); aqueous solutions of such salts have surface-active and detergent properties. Salts of alkaline earth and heavy metals are conventionally called metal soaps; most of them are insoluble in water.

In the anhydrous state, sodium and potassium salts of fatty acids are crystalline solids with t o pl. 220 o -270 o. Anhydrous soaps, especially potassium soaps, are hygroscopic; Moreover, salts of unsaturated fatty acids are more hygroscopic than saturated salts.

In hot water at a temperature close to the boiling point, soaps dissolve in all respects; at average room temperatures, their solubility is limited and depends on the nature and composition of acids and alkalis.

Soaps, which contain large quantities of salts of high molecular weight solid fatty acids, in cold water they foam poorly and have low cleaning power, whereas soaps made from liquid oils, as well as from solid low molecular weight fatty acids, such as coconut oil, wash well at room temperature. Soaps, being salts of alkali metals and weak organic acids, when dissolved in water undergo hydrolysis with the formation of free alkali and acids, as well as acid salts, which for most fatty acids are poorly soluble precipitates that impart turbidity to solutions. For salts of various fatty acids, hydrolysis increases with increasing molecular weight, decreasing soap concentration, and increasing solution temperature. Due to hydrolysis, aqueous solutions of even neutral soaps have an alkaline reaction. Alcohol inhibits the hydrolysis of soaps.

Soaps in aqueous solutions are partly in a true solution state, partly in a colloidal polydisperse state, forming a complex system consisting of molecules and micelles of neutral soap, its ions and other hydrolysis products.

With decreasing polarity of the solvent, i.e. with the transition from water to organic liquids, such as alcohol, the colloidal properties of soap solutions decrease. The solubility of soaps in methyl and ethyl alcohol is much higher than in water, and in anhydrous alcohols soap is in a state of true solution. Concentrated solutions of solid fatty acid soaps in ethyl alcohol, prepared by heating, give solid gels when cooled, which is used in technology to prepare the so-called solid alcohol.

Soaps are almost insoluble in anhydrous ether and gasoline. The solubility of acidic soaps in gasoline and other hydrocarbon liquids is much higher than neutral ones. Alkaline earth metal salts of higher fatty acids, as well as heavy metal salts, are insoluble in water. Metal soaps dissolve in fats, which is used in the production of drying oils, where these soaps act as catalysts to accelerate the drying process of fatty oils. The solubility of soaps in mineral oils is used in technology in the production of greases (solids).

The widespread use of soaps as detergents, wetting agents, emulsifiers, peptizers, lubricants and active hardness reducers, for example, when cutting metals, is explained by the specific structure of their molecules. Soaps are typical surfactants.

There's so much soap out there today! Multi-colored, bright, beautiful. There is a transparent one, in which patterns or fruits, different images are temptingly visible. Very popular types for children are those made in the shape of their favorite cartoon characters and other characters. In general, soap manufacturers are trying their best. But what is this product like from the inside? What is its chemical composition, when did it appear and how is it obtained? Let's try to figure it out.

Chemical base of soap

From a scientific point of view, this product is the result of alkaline hydrolysis of oils or fats. For the first time, Michel Chevrel, a French chemist, guessed that soaps and fats had something in common. He devoted almost his entire life to the study of higher carboxylic acids. Therefore, he is credited with the theoretical explanation of the composition of fats, and therefore soap.

Chevreul said that if the higher trihydric alcohol glycerol, containing three hydroxo groups, reacts with an acid, the general formula of which is R-COOH, then triglycerides - acid esters - will be formed as a result. They will be fats. If the reaction is carried out in an alkaline medium, the resulting product will react with NaOH (KOH) to form soap.

Later, these theoretical conclusions were supported by Berthelot's experiments in laboratory conditions. Typically, different soaps include the following components:

water;
naphthenic acids;
stearic;
palmitic;
rosin;
or potassium.

Therefore, the chemical formula of soap is conventionally written as follows: R-COOMe, where R is a radical containing from 8 to 20 or more carbon atoms. Me is a metal, alkaline or alkaline earth.

If we talk about a regular household product used for washing clothes, the soap formula will look something like this: C 17 H 35 -COONa. It includes:

stearic acid;
sodium hydroxide;
rosin;
water;
sometimes coconut oil is used.

In different countries, the production of this type of product occurs in different ways, so most often the result differs in composition, color, and wash quality. Thus, the soap formula itself becomes clear. Chemistry gives the following definition to this product: these are salts of higher carboxylic acids, including alkali or alkaline earth metals.

It should be noted that the products vary greatly in their state of aggregation, transparency, smell and other organoleptic parameters. It all depends on the chemical composition and production method.

Liquid soap formula

Liquid products have been a very popular detergent option lately. It is convenient, it seems to be more gentle on the skin of your hands and is aesthetically pleasing for the bathroom shelf. Therefore, liquid soap is one of the most common types of these salts. How do they differ from solids and why is there such a difference in states of aggregation?

It turns out that it all depends on the metal cation that forms the compound, as well as the production technology. The formula of the soap, which is liquid, looks like this: R-COOK. That is, the composition necessarily includes potassium ions. Accordingly, potassium hydroxide takes part in production.

Main characteristics of such products:

viscosity;
hygroscopicity;
ductility;
transparency;
better solubility.

Solid soap

To obtain the product in a more traditional state of aggregation, you need to use soda lime, or caustic soda, in production. It should be noted that if the composition contains Na ions, then the product turns out to be solid and nothing else. Lithium ions most often also form similar soaps.

Thus, the soap formula takes on a slightly different form: R-COONa, R-COOLi. From a chemical point of view, the quantitative composition and structure of the substances does not change - soap corresponds to its nature, being salts of carboxylic acids. Physical characteristics, organoleptic properties, external design - all this is subject to change by the person himself, which is what people actively do.

Classification

Two bases can be identified for dividing the described substances into categories. The first sign of classification is the chemical basis during manufacture. According to this criterion, the following are distinguished:

sound soap - fatty acids of at least 60% in the composition;
semi-core - about 30%;
adhesive - not higher than 47%.

The chosen base can give the soap completely different external design options. You can make it marbled, transparent, with decorations and components built inside, colored and matte, and so on. The soap formula will also be expressed by the general composition of R-COOMe, but the product itself often also includes rosin and naphthenic acids, as well as sorbitol, fragrances, dyes, preservatives, foaming agents and other compounds.

The second classification feature is household use. So, there are three types of product.

Toilet - used for cosmetic purposes for washing, washing the body. It should have good foaming ability, be soft and not cause irritation or dryness. To achieve this, fatty acids should not be reduced beyond 72% in the composition.
Special - used in the leather, textile industries, medicine and so on. Contains special technical additives.
Household - intended for washing household items, washing clothes, cleaning and other household needs.

The formula of this type of soap is no different from the previous one; it can also be transparent, matte, colored, and so on. The ratio of components varies depending on the purpose.

Industrial production

Soap production on a large scale is carried out in special soap factories. There, using pre-planned and outlined technologies and designs, a huge number of copies of the product, both solid and liquid, have been produced. The main technological chains are as follows:

between soda ash and fat hydrolysis products (carboxylic acids);
interaction with or caustic soda;
alkaline hydrolysis of triglycerides.

In any case, you can get different soaps based on their physical and chemical properties.

History of soap making

It is known that people knew about making soap more than 6 thousand years ago, that is, even before our era. In Ancient Egypt, ash was boiled with the addition of fat and the desired product was obtained. Future generations continued to act this way for several centuries in a row.

In Europe, soap production was weakly intensive, since no one cared about the cleanliness of their bodies; it was considered shameful. And only from the 18th century did soap making reach its peak. New simplified production technologies have been invented, aromatic oils and softening additives are included in soap, it becomes more diverse and pleasant to use.

DIY making

How to make soap with your own hands? Is it possible? The answer is clear: yes, it is possible. Today, many people have made this their home business and are earning very good money from it.

If you have creative imagination, creativity and out-of-the-box thinking, dexterous hands, desire and space for work, then making soap will not be difficult at all.

Soap making technology at home

There are three main ways to prepare the product without leaving home.

Purchase a special ready-made base for production. This is a convenient, inexpensive and quick option for making soap with your own hands. This base requires only your imagination and the addition of the necessary flavors and dyes. It is plastic and easy to handle, it can be given any shape. It is also possible to obtain a transparent product if desired.
Buy ready-made soap without fragrances, dyes and aromatic additives. For example, children's. Then chop, melt in a water bath, and continue to act as in the first case.
Cooking from scratch. The most dangerous and labor-intensive process from a safety point of view. Can be carried out using any of the described industrial methods. However, it should be remembered that you should work with alkalis with extreme caution. And not at home, but in a special room.

Hello, dear readers of the project website !

Today I want to introduce you to information about the composition of simple soap that we use every day in everyday life. Have you ever wondered what substances manufacturers add to soap to get bright colors, convenient shape, delicate aroma...

In this article I will try to tell you about the composition of soap, the dangerous substances in it, and how to choose it correctly, what you need to pay attention to before purchasing so as not to harm your health.

A LITTLE HISTORY

First of all, I would like to introduce you to the history of soap. Many scientists believe that it was invented by the Gallic tribes. They used a mixture of beech tree ash and lard to cleanse their hair and body. A little later, the Romans borrowed the soap-making recipe, adding seaweed to improve its characteristics.

Nowadays, manufacturing technology has stepped far forward. New opportunities have emerged and recipes have changed in soap making. A large assortment of different soaps appeared: baby soap, toilet soap, laundry soap, etc. Huge competition began among manufacturers, and a strong struggle was felt for every consumer of these products.

In order to win the championship in this race and remain a leader in their niche, many manufacturers have to resort to tricks. The most important role is played by price (the product that costs less wins). In order to reduce the cost of soap, they began to add cheap components to the recipe, which greatly reduce production time and increase its shelf life. Unfortunately, they can be harmful to human health.

To make soap, manufacturers use basic and auxiliary raw materials. The main raw materials can be both technical and food. Pork and lamb fat, sometimes combined fats, are often used. The following types of basic raw materials are used in production:

WHAT MAY BE INCLUDED IN THE BASIC RAW MATERIALS OF SOAP

May be natural fatty raw materials(animal or vegetable).
May be synthetic fat raw materials.
May be fat processing products.
May be included fatty acid or synthetic fatty acids.

Fatty acids are formed during the breakdown of fat and natural oils. Synthetic fatty acids are formed as a result of oxidation processes of paraffin (petroleum).

May be included esters(for example palm stearate).

WHAT MAY BE INCLUDED IN SOAP AUXILIARY RAW MATERIALS

Surfactants (surfactants).

Surfactants are substances (mostly of chemical origin), the main purpose of which is to remove fat. Due to its ability, the surfactant molecule retains a particle of water with one part (hydrophilic) and retains a particle of fat with the other part (lipophilic).

The protective layer of human skin also consists of fat. It turns out that by using soap with a large amount of surfactants, we leave our skin defenseless against germs.

According to the level of increase in toxicity, surfactants can be divided into: nonionic, anionic and cationic (experts believe that it is cationic ones that cause the most harm to our body).

Preservatives.

Their main function is to preserve the properties of products for a long time, protecting them from the effects of bacteria. Here are some of the most common preservatives that can be found in soap:

- methylparaben. It does a good job of killing bacteria and protecting against fungus. Made from benzoic acid.

- phenoxyethanol. This is a chemical component that does an excellent job of protecting against bacteria and as an antibacterial detergent.

- Сapryl Glycol is a preservative whose main function is to protect soap from various microorganisms. Softens and smoothes the skin.

- Sorbic acid (Sorbit Acid).

This preservative effectively inhibits the growth of microorganisms (mold and fungi). It is considered not hazardous to health.

Dyes.

The main function of dyes is to create color.

- Titanium dioxide (E171). Gives a white color to the material. Harm to health has not been proven. Experts have come to the conclusion that only titanium dioxide dust is dangerous to humans. It is strictly forbidden to inhale it.

- Dyes CI 12490, CI 15510 can often be found in soap.

Structure formers.

The main role of structure formers is to enhance cleaning abilities. They prevent the soap from becoming sticky and breaking into pieces.

-Stearic acid. Its main task is to combine different components in soap. It is considered one of the most important components that are included in soap. health has not been studied. It is non-toxic and does not cause health problems.

Solvents.

Their main role is to impart a new smell to soap, drowning out the original one. The smell can be rich in fruity or floral aroma, etc. . Meet:

- Isopropyl myristate (IPM).

- Dipropylene glycol (DPG).

Stabilizers (antioxidants).

Their main role is to prevent oxidative processes in soap (it begins to darken). These include:

-Antal.

-Sodium silicate.

Antibacterial substances.

Their main function is to enhance the antiseptic properties of soap. Can be found:

-Triclosan.

-Boric acid.

-Birch tar.

-Triclocarban.

Deodorizing additives.

Their main role is to hide the smell of sweat.

-Methanil.

Medicinal supplements.

Special components that improve the properties of the product, making it beneficial for the human body. These include:

-Infusions.

-Vitamins.

Alkaline substances

They are intended for saponification of fatty raw materials. They neutralize fatty acids. This group includes:

-Sodium hydroxide.

-Soda Ash.

Overcooking additives.

They are designed to reduce the degreasing effect of soap. Meet:

- Glycerol.

-Lanolin.

The composition of the soap may vary. Much depends on the consistency (soap can be solid, liquid, creamy, powdery), on the type of action of the soap (exfoliating, moisturizing, antibacterial). The period of its storage is also important (from 6 months to 3 years).

We have become familiar with the components that are used in soap making, and now let's study how some of them affect health. Here is a list of diseases that they can cause:

INFLUENCE OF SOAP COMPONENTS ON HUMAN HEALTH

Allergic reactions on the skin (rash, redness, dermatitis).
Negatively affects reproductive function in men.
Destroy the protective layer of the skin.
Accelerate skin aging.
There is a disruption of the gastrointestinal tract.
Degreasing and dehydration of the skin occurs.
Hormonal imbalance.
Decreased immunity.
Promotes the formation of oncology (upon contact with the body in large quantities).
Destruction of vitamins in the body (for example B12).
Liver disease.
Impaired kidney function.
Visual impairment.

This list is not complete. The effect of many components on the human body has not yet been studied. Unfortunately, more and more products in supermarkets and stores contain components that are hazardous to health. This soap is cheap and is in great demand among consumers.

The components that are first on the list of soap composition have a higher concentration than those that are found at the end of the list.

Carefully study the composition of the soap you want to purchase.
Don't buy cheap soap.
Do not buy soap that contains sodium lauryl sulfate (SLS or SLES).
Avoid products with complex names of components in the composition.
It is advisable to purchase soap with fewer synthetic components.
Do not buy soap that contains a substance - amber nitro-musk fragrance.
Buy detergent that contains coconut oil.
Avoid products with triclosan (in liquid antibacterial soap).
It is recommended to purchase natural soap or make it yourself.
Do not trust advertising (the task of advertising is to sell a product).
Buy products only from well-known manufacturers who have proven themselves positively in the market.

WE Draw CONCLUSIONS

The choice of soap should be taken very seriously, especially if you are buying it for your child. It is necessary not to react to the beautiful packaging, shape or smell of the product, but to focus your attention on the composition. It is recommended to use plain soap in everyday life, without additives.

You cannot use bactericidal soap - it destroys microorganisms that protect human skin (can be used in rare cases, only for wounds and scratches). Learn to make soap at home - you will be 100% sure that it is natural. The less chemicals, the better the product.

I bring to your attention an interesting video clip that talks about the dangers of using antibacterial soap. I hope this information will be useful to you. Enjoy watching.

Definition

Soap- liquid or solid products containing surfactants, in combination with water, used for cleansing and skin care (toilet soap, shampoos, gels), or as a household chemical - detergent (laundry soap).

Chemical composition of soap

From a chemical composition point of view:

solid soaps- mixture of soluble sodium salts higher fatty (saturated and unsaturated) acids;

liquid soaps- mixture of soluble potassium or ammonium salts the same acids

One of the options for the chemical composition of solid soap is $C_(17)H_(35)COONa$, liquid soap is $CC_(17)HH_(35)COOK$. Fatty acids from which soap is made include:

stearic(octadecanoic acid) - $C_(17)H_(35)COOH$, solid, monobasic saturated carboxylic acid, one of the most common fatty acids in nature, included in the form of glycerides in the composition lipids, primarily triglycerides of fats of animal origin (in lamb fat up to ~30%, in vegetable fat (palm oil) - up to 10%).
palmitic(hexadecanoic acid) - $C_(15)H_(31)COOH$, the most common solid monobasic saturated carboxylic acid (fatty acid) in nature, is part of the glycerides of most animal fats and vegetable oils (butter contains 25%, lard - 30%), many vegetable fats ((palm, pumpkin, cottonseed oils, Brazil nut oil, cocoa, etc.);
myristic (tetradecanoic acid) - $C_(13)H_(27)COOH$ - monobasic saturated carboxylic acid, found in nature as a triglyceride in almond, palm, coconut, cottonseed and other vegetable oils
lauric(dodecanoic acid) - $C_(11)H_(23)COOH$ - monobasic saturated carboxylic acid, as well as myristic acid, is found in many vegetable oils of southern cultures: palm, coconut, plum kernel oil, tucuma palm oil, etc.
oleic(cis-9-octadecenoic acid) - $CH_3(CH_2)_7-CH=CH-(CH_2)_7COOH$ or general formula $C_(17)H_(33)COOH$ - liquid monobasic monounsaturated fatty acid, belongs to the omega group -9 unsaturated fatty acids, found in large quantities in animal fats, especially fish oil, as well as in many vegetable oils - olive. sunflower, peanut, almond, etc.

Additionally, soap may contain other substances that have a detergent effect, as well as flavors and dyes. Often, to improve consumer properties, glycerin, talc, and antiseptics are added to soap.

Methods for making soap

All methods for producing soap are based on the reaction of alkaline hydrolysis of fats (animal or vegetable):

Making solid soap

To prepare solid soap, you need to take about 30 g of lard and about 70 g of beef fat. Melt all this, and when the fat melts, add 25 g of solid alkali NaOH and 40 ml of water. The lye must be heated before adding.

Attention! You need to work with alkali carefully so that its splashes do not get on your skin.

Continue heating for half an hour over low heat, remembering to stir (it is better to stir with a glass rod). As the water boils, you need to add preheated water to the mixture.

To separate (salt out) the resulting soap from the solution, you can use a solution of table salt (NaCl). To prepare it, you need to dissolve 20 g of NaCl salt in 100 ml of water. After adding salt, continue heating the mixture. As a result of salting out, soap flakes appear on the surface of the solution. After cooling, you need to collect the flakes that appear from the surface of the solution with a spoon and squeeze them out using a cloth or gauze. To prevent alkali residue from getting on your hands, it is best to carry out this operation with rubber gloves.

The resulting mass should be washed with a small amount of cold water and, to obtain a pleasant aroma, you can add an alcohol solution of a fragrant substance (for example, perfume). You can also add coloring and antiseptic substances. Then knead the whole mass and, with slight heating, form the desired shape.

When producing toilet soap on an industrial scale, vegetable fats, rather than animal fats, are mainly used. How many different fats there are, so many different types of soap can be made. For example, liquid soaps (with the exception of olive oil) are predominantly obtained from vegetable oils, but unlike solid soap, liquid soap is not separated by “salting out”.

Preparation of liquid soap

The preparation of liquid soap, as well as the preparation of solid soap, is carried out by alkaline hydrolysis, but, unlike the previous method, you need to use a solution of potassium hydroxide (KOH). Instead of animal fat, you can take vegetable oil with the addition of 30 g of potassium alkali (KOH) and 40 ml of water.

Attention! Just like when preparing solid soap, alkali is a caustic substance; it is better to work with gloves.

All operations are carried out similarly to the first method. However, instead of salting it out, you need to let the solution cool, stirring constantly. This creates a mixture of soap and water, plus a small amount of unreacted substances called “glue soap.” There is no need to separate the mixture. because it has cleaning properties.

SURFACTANTS (SURFACTANTS)

Definition

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

The main quantitative characteristic of a surfactant is surface activity - the ability of a substance to reduce surface tension at the interface.

Surfactants are organic compounds containing polar part, that is hydrophilic component(functional groups of acids and their salts -OH, -COO(H)Na, -$OSO_2O(H)Na$, -$SO_3(H)Na$) and non-polar(hydrocarbon) part, that is hydrophobic component.

As already stated, soaps are surfactants. In addition to various types of soap, surfactants also include various synthetic detergents (SMC), as well as alcohols, carboxylic acids, amines, etc.

On based on the chemical nature of molecules,Surfactants are divided into four main classes: anionic, cationic, nonionic and amphoteric.

1. Anionic surfactants contain one or more polar groups in the molecule and dissociate in an aqueous solution to form chains of anions that determine their surface activity. The hydrophobic part of the molecule is usually represented by saturated or unsaturated aliphatic chains or alkylaromatic radicals. In total, six groups of anionic surfactants are distinguished. The most common anionic surfactants are alkyl sulfates and alkylaryl sulfonates. These substances are low toxic, do not irritate human skin and undergo satisfactory biological decomposition in water bodies, with the exception of alkylaryl sulfonates with a branched alkyl chain. Anionic surfactants are used for the production of washing powders and cleaning products.

2. Cationic surfactants dissociate in aqueous solution to form a surfactant cation with a long hydrophobic chain and an anion, usually a halide, sometimes a sulfuric or phosphoric acid anion. Nitrogen-containing compounds predominate among cationic surfactants. Cationic surfactants reduce surface tension less than anionic surfactants, but they can interact chemically with the surface of the adsorbent, for example with bacterial cellular proteins, causing a bactericidal effect. Cationic surfactants reduce surface tension less than anionic surfactants, but they can be used to soften fabrics. Cationic surfactants are also included in washing powders and cleaning products, but in addition, shampoos, shower gels and fabric softeners are prepared on their basis.

3. Nonionic surfactants do not dissociate into ions in water. Their solubility is due to the presence in the molecules of hydrophilic ether and hydroxyl groups, most often the polyethylene glycol chain. A characteristic feature of nonionic surfactants is their liquid state and low foaming in aqueous solutions. Such surfactants clean polyester and polyamide fibers well.

4. Amphoteric (ampholytic) surfactants contain in the molecule a hydrophilic radical and a hydrophobic part that can be an acceptor or donor of a proton, depending on the pH of the solution. Typically these surfactants include one or more basic and acidic groups. Depending on the pH value, they exhibit the properties of cationic or anionic surfactants. From the group of amphoteric surfactants, betaine derivatives (for example, cocaminopropyl betaine) are most often used. In combination with anionic surfactants, they improve foaming ability and increase the safety of detergents. These derivatives are obtained from natural raw materials, so they are quite expensive components. Amphoteric and nonionic surfactants are used in the production of delicate detergents - shampoos, gels, and cleansers.

INFLUENCE OF PASTERANTS ON HUMANS AND ENVIRONMENTAL COMPONENTS

Aqueous solutions of surfactants in greater or lesser concentrations enter water bodies with industrial and domestic wastewater. Much attention is paid to the treatment of wastewater from surfactants, since due to the low rate of decomposition, the negative impact on plant and animal organisms is difficult to predict. 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 content of dissolved oxygen in the water decreases, which in turn worsens the conditions for the existence of other living forms in the water. body of water

Like any environment in the biosphere, a body of water has its own protective powers and has the ability to self-purify. Self-purification occurs due to dilution, settling of particles to the bottom and formation of deposits, decomposition of organic substances to ammonia and its salts due to the action of microorganisms. The great difficulty of self-healing of water bodies after exposure to surfactants is that surfactants are most often present in the form of a mixture of individual homologs and isomers, each of which exhibits individual properties when interacting with water and bottom sediments, and the mechanism of their biochemical decomposition is also different. Studies of the properties of surfactant mixtures have shown that in concentrations close to the threshold, these substances have the effect of summing up their harmful effects.

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. One of the main negative effects of surfactants in the environment is a decrease in surface tension. In water bodies, changes in surface tension lead to a decrease in oxygen concentration in the water mass, which causes an increase in the biomass of blue-green and brown algae and the death of fish and other aquatic organisms.

Only a few surfactants are considered safe (alkyl polyglucosides), since their breakdown products are carbohydrates. However, when surfactants are adsorbed on the surface of particles (silt, sand), the rate of their destruction decreases many times over. Therefore, under normal conditions, they can release (desorb) heavy metal ions held by these particles, and thereby increase the risk of these substances entering the human body.

Surfactants can enter the human body in different ways - with food, water, through the skin. Surfactant components can cause allergic reactions, including severe complications.

The structure of soap (chemistry of soap)

Soaps are sodium or potassium salts of higher fatty acids (Scheme 1), which hydrolyze in an aqueous solution to form acid and alkali.

General formula of solid soap:

Salts formed by strong alkali metal bases and weak carboxylic acids undergo hydrolysis:

The resulting alkali emulsifies, partially decomposes fats and thus releases dirt stuck to the fabric. Carboxylic acids form foam with water, which captures dirt particles. Potassium salts are more soluble in water than sodium salts and therefore have stronger cleaning properties.

The hydrophobic portion of the soap penetrates the hydrophobic contaminant, resulting in the surface of each contaminant particle being surrounded by a shell of hydrophilic groups. They interact with polar water molecules. Due to this, the ions of the detergent, along with the contamination, are detached from the surface of the fabric and pass into the aqueous environment. This is how the contaminated surface is cleaned with a detergent.

Soap production consists of two stages: chemical and mechanical. At the first stage (soap cooking), an aqueous solution of sodium (less often potassium) salts, fatty acids or their substitutes is obtained.

Production of higher carboxylic acids during cracking and oxidation of petroleum products:

Preparation of sodium salts:

СnHmCOOH + NaOH = СnHmCOONa + H2O.

Soap cooking is completed by treating the soap solution (soap glue) with excess alkali or sodium chloride solution. As a result, a concentrated layer of soap, called a core, floats to the surface of the solution. The resulting soap is called sound soap, and the process of separating it from the solution is called salting or salting out.

Mechanical processing consists of cooling and drying, grinding, finishing and packaging of finished products.

As a result of the soap-making process, we obtain a wide variety of products that you can familiarize yourself with.

The production of laundry soap is completed at the salting out stage, during which the soap is cleaned from protein, coloring and mechanical impurities. The production of toilet soap goes through all stages of mechanical processing. The most important of these is grinding, i.e. transferring sound soap into a solution by boiling with hot water and salting out again. In this case, the soap turns out to be especially clean and light.

Washing powders can:

* irritate the respiratory tract;
* stimulate the penetration of toxic substances into the skin;
* cause allergies and skin dermatitis.

In all these cases, you need to switch to using soap, the only drawback of which is that it dries out the skin.

If the soap was made from animal or vegetable fats, then glycerin formed during saponification is separated from the solution after separating the kernel, which is widely used: in the production of explosives and polymer resins, as a fabric and leather softener, in the manufacture of perfumes, cosmetics and medical preparations, in production of confectionery products.

In the production of soap, naphthenic acids are used, released during the purification of petroleum products (gasoline, kerosene). For this purpose, petroleum products are treated with a solution of sodium hydroxide and an aqueous solution of sodium salts of naphthenic acids is obtained. This solution is evaporated and treated with table salt, as a result of which a dark-colored ointment-like mass - soap naphtha - floats to the surface of the solution. To clean soaponaft, it is treated with sulfuric acid. This water-insoluble product is called asidol or asidol-mylonaft. Soap is made directly from asidol.

Soap raw materials

General information on the raw materials from which soap is made.

Animal fats are an ancient and valuable raw material for soap making. They contain up to 40% saturated fatty acids. Artificial, that is, synthetic, fatty acids are obtained from petroleum paraffin by catalytic oxidation with atmospheric oxygen. During oxidation, the paraffin molecule is broken in different places, and a mixture of acids is obtained, which are then separated into fractions. In soap production, mainly two fractions are used: C10-C16 and C17-C20. Synthetic acids are introduced into laundry soap in an amount of 35-40%.

Naphthenic acids, released during the purification of petroleum products (gasoline, kerosene, etc.), are also used to produce soap. for this purpose, petroleum products are treated with a solution of sodium hydroxide and an aqueous solution of sodium salts of naphthenic acids (monocarboxylic acids of the cyclopentane and cyclohexane series) is obtained. This solution is evaporated and treated with table salt, as a result of which a dark-colored, ointment-like mass - soap naphtha - floats to the surface of the solution. To purify soap naphtha, it is treated with sulfuric acid, that is, the naphthenic acids themselves are displaced from the salts. This water-insoluble product is called asidol, or asidolmylonaft. Only liquid or soft soap can be made directly from asidol. It has an oily smell, but it has bactericidal properties.

In the production of soap, rosin has long been used, which is obtained by processing the resin of coniferous trees. Rosin consists of a mixture of resin acids containing about 20 carbon atoms in the carbon chain. 12-15% of rosin by weight of fatty acids is usually added to the composition of laundry soap, and no more than 10% is added to the formulation of toilet soaps. The introduction of rosin in large quantities makes the soap soft and sticky.

Of course, today it is important to use a variety of vegetable fats; there is a separate article about them in the section.

In addition to using soap as a detergent, it is used in bleaching fabrics, in the production of cosmetics, and for the manufacture of polishing compounds for water-based paints.

Detergents must have the ability to be adsorbed on the boundary surface, that is, they must have surfactants.

Salts of heavy carboxylic acids, for example CH3(CH2)14COONa, are typical surfactants. They contain a hydrophilic part (in this case, a carboxyl group) and a hydrophobic part (hydrocarbon radical).

Properties of soaps. What is soap?

Soaps are salts of high molecular fatty acids. In technology, soaps are sodium or potassium salts of higher fatty acids, the molecules of which contain at least 8 and no more than 20 carbon atoms, as well as similar naphthenic and resin acids (rosin); aqueous solutions of such salts have surface-active and detergent properties. Salts of alkaline earth and heavy metals are conventionally called metal soaps; most of them are insoluble in water.

In the anhydrous state, sodium and potassium salts of fatty acids are solid crystalline substances with melt. 220o-270o. Anhydrous soaps, especially potassium soaps, are hygroscopic; Moreover, salts of unsaturated fatty acids are more hygroscopic than saturated salts.

Soaps, which contain large amounts of salts of high molecular weight solid fatty acids, do not foam well in cold water and have low cleaning power, while soaps made from liquid oils, as well as from low molecular weight solid fatty acids, such as coconut oil, wash well at room temperature . Soaps, being salts of alkali metals and weak organic acids, when dissolved in water undergo hydrolysis with the formation of free alkali and acids, as well as acid salts, which for most fatty acids are poorly soluble precipitates that impart turbidity to solutions. For salts of various fatty acids, hydrolysis increases with increasing molecular weight, decreasing soap concentration, and increasing solution temperature. Due to hydrolysis, aqueous solutions of even neutral soaps have an alkaline reaction. Alcohol inhibits the hydrolysis of soaps.

soap sodium salt potash

How to prepare caustic soda and potash

Purity of soda

The higher the percentage, the purer the soda. Chda is not a manufacturer, but a qualification. There is also ch - pure, khch - chemically pure and special purity - the highest purification.

GOST reagent grade is 4328-77 (the final numbers are the year the GOST was adopted), and according to analysis, this soda is reagent grade - 99%, but is still considered not the purest. (Soda has 99.9% purity, reagent grade - 99.99%...).

If you don’t have ready-made caustic soda or potassium, you can prepare:

the first of soda ash or crystalline soda and slaked lime,

and the second is made of potash and slaked lime.

Sodium hydroxide. For 1 kg of soda ash, or for 2.85 kg of crystalline soda, take 900 g of slaked lime. Prepare a soda solution with a strength of 30°C at 23°B, for which 1 kg of soda is dissolved in 4.5-4.6 liters of water.

The soda solution is placed in a boiler or the soda is immediately dissolved in a cooking kettle, the liquid is heated to 60 C and slaked lime mixed with water - “milk of lime” - is poured in small portions. In this case, the solution foams very much and can go over the edge. Therefore, the boiler should be loaded only to 2/3 of its capacity and the liquid should be vigorously stirred during cooking.

The more thoroughly the liquid is mixed, the better the process of converting ordinary soda into caustic soda (caustic soda).

The mixture must be heated for 40--60 minutes, then it is allowed to settle and the clear solution is drained from the sediment.* The transparent liquid is a solution of caustic soda of approximately strength 20°--21° B, and part of the undissolved lime remains in the sediment, the remains of caustic soda , chalk and other impurities. After removing the clear solution, you can add water to the precipitate, boil it several times, let it settle and drain the clear liquid again, which will also be a solution of caustic soda, but of much lower strength.

When making caustic soda in this way, the solution is 20°-21° B. If a stronger alkali is needed to saponify the fat from which soap is supposed to be made, the resulting solution can be evaporated; As the water evaporates, the solution will become stronger. If a lower strength alkali is needed, the solution is diluted with water.

With this homemade production of caustic soda (caustic soda) from 1 kg of soda ash, 780-820 g of caustic soda is obtained.

It was indicated above that you need to take 1 kg of soda ash, and 2.85 kg of crystalline soda. The difference between soda ash and crystalline soda is that the latter contains water of crystallization.

If crystalline soda is calcined, it crumbles with a crash and turns into a white powder, already completely devoid of water (calcined).

Caustic potassium. Caustic potassium is prepared using the same method as caustic soda. For 1 kg of calcined potash, take 6.8-7 kg of slaked lime and 10-11 liters of water. A solution of potash in water is heated without bringing it to a boil, and slaked lime mixed with water (lime milk) is added to the boiler in small portions. The liquid is vigorously stirred all the time and heating is continued for 40-60 minutes. Then the mixture is allowed to settle, the clear liquid, which is a solution of caustic potassium with an approximate strength of 16-17° B, is poured off, and the sediment is again doused with water, heated to a boil, allowed to settle, and the clear liquid, which is a solution of a much lower strength, is poured off.

Potash can be prepared at home - by extracting it (by leaching) from plant ash, from ash obtained from burning wood, and in general from any wood or plant ash. The ash is placed in a vessel that has a hole in the bottom, lightly compacted and water is poured onto the ash. Water will seep through the ash and flow out of the hole in the bottom in the form of a cloudy liquid, which is collected in a separate vessel. Then the wet ash is removed, fresh ash is poured in, which is doused with the resulting cloudy liquid from the moistened first ash. This operation is repeated until the same water, passed through several portions of ash, becomes thick. The thick liquid is passed through a thin cloth to remove solid particles and heated in a deep iron pan until the water evaporates.

As the water evaporates, a gray scum will remain on the bottom and walls of the pan, which is collected in another vessel. The collected scale is heated over high heat in a frying pan and a white powder is obtained - potash.

Potassium alkali can also be prepared from plant or wood ash as follows: the ash sifted through a sieve is placed in heaps on a compacted earthen or stone floor and a small amount of water is poured over it to make it moist. Then, depressions are made in the piles, about 8-10% of quicklime is poured in, poured in, everything is mixed well, and when all the lime is quenched, it is sprinkled with ash on top. The cooled and well-mixed mass is placed in a vat with two bottoms, of which the top has many small holes. A piece of rough canvas is placed on the upper bottom and a mixture of ash and lime is poured. Between both bottoms, on one side, a hole is made into which a tube is inserted to remove air, and on the opposite side a valve is attached to drain the liquor. Warm water is poured onto the ash and lime, mixed well and allowed to stand for 6-8 hours. After this, lye is released through the tap, having approximately a strength of 20-25 ° B.

The second pouring of water will give lye with a strength of 8--10° B, the third - at 4--2° B.

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Properties of soaps. What is soap?

Chemical base of soap

Liquid soap formula

Solid soap

Classification

Industrial production

History of soap making

DIY making

Soap making technology at home

A LITTLE HISTORY

WHAT MAY BE INCLUDED IN THE BASIC RAW MATERIALS OF SOAP

WHAT MAY BE INCLUDED IN SOAP AUXILIARY RAW MATERIALS

INFLUENCE OF SOAP COMPONENTS ON HUMAN HEALTH

WE Draw CONCLUSIONS

Chemical composition of soap

Methods for making soap

Making solid soap

Preparation of liquid soap

SURFACTANTS (SURFACTANTS)

INFLUENCE OF PASTERANTS ON HUMANS AND ENVIRONMENTAL COMPONENTS

The structure of soap (chemistry of soap)