Purposes of alkaline electrolytes

1. Ability to removal of pollutions increases with increase of рН of solution. It concerns both to soap, and to synthetic detergents in soft and hard water. The most active in this respect are metasilicate, trisodiumphocphate, carbonic soda.

2. Mitigation of water owing to formation of complexes with alkaline-earth and heavy metals (especially trisodiumphocphate).

3. Alkaline salts promote the removal of pollutions because they increase swelling of fibres, and it promotes faster removal of microdisperse pollutions.

4. Play the role of protective colloids and prevent repeated sedimentation of pollutions on a fabric.

5. Raise washing action of active substance in synthetic detergents that allows to reduce their concentration at washing.

6. Increase the foaming ability.

7. Facilitate the rinsing of linen, i.e. promote the faster removal of active substance from a fabric.

8. Peroxide salts cause the bleach of fabrics allocated active oxygen and allow to delete stains from fruit, vegetables, vine, coffee, cocoa from fabrics.

9. Silicate of sodium protects the equipment from corrosion by synthetic detergents.

Control questions

1. Which kinds of inorganic salts are used in compositions of synthetic detergents?

2. Which alkaline salts of inorganic acids are included in structure of synthetic detergents? Write the hydrolysis equation of their salts.

3. Which neutral salts of inorganic strong acids are included in structure of synthetic detergents? Write the hydrolysis equation of their salts.

4. Which peroxide salts are entered in structure of detergents?

5. The purpose of sodium silicates in compositions of SD.

6. Purposes of alkaline electrolytes.

2.2 Organic components used in synthetic detergents structure

A structure of synthetic detergents includes some organic products raising their quality. There are antyresorbents, alkylolamides, bleaches, regulators of environment, aromatic substances, hydrotropic substances and other compounds.

Antyresorbents are the substances interfering repeated sedimentation of pollutions on the cleared surface. The most widespread antyresorbent is sodium carboxylmethilcellulose.

Sodium carboxylmethilcellulose. The basic purpose of introduction of this compound in structure of synthetic detergents is prevention of repeated sedimentation of pollutions on a fabric. Carboxylmethilcellulose protects from greying only cotton fabrics, but it is inefficient for woolen and silk fabrics. For this purpose in structure of synthetic detergents polyvinilpirrolidon is entered.

Alkylolamides represent the class non-ionogenic SAS. Highly active alkylolamides are received by heating of one mole of diethanolamine with one mole of methyllaurate at presence of catalyst.

Monoethanolamides are used by manufacture of powder synthetic detergents for increasing of their foaming ability and foam stability. Diethanolamides are widely applied in liquid detergents to washing of utensils, in shampoos for washing of hair. Alkylolamides render beneficial influence on integument of a person.

Alkylolamides are frequently entered in toilet soaps in quantity of 2-2,5 %. They raise the foaming, protect a soap from formation of cracks, intensify a smell, raise the washing ability of soaps and stability of paints, give to soaps plasticity, raise dispersion of calcium soaps.

Alkylolamides protect metals from corrosion. Alkylolamides on basis of low-molecular acids (С₇-С₉) are used in a dry-cleaner as raise solubility of washing substances in organic solvents.

Components giving whiteness.

Components, giving whiteness to fabrics, are optical and chemical bleaches and enzymes.

Optical bleaches in detergents on their purpose are divided on bleaches for cotton, chlorine bleaches, and bleaches for polyamide and polyester fabrics. Bleaches are produced usually on basis of organic substances.

Optical bleaches (dyes). To increase whiteness of washing fabrics chemical bleaching means are applied: sodium perborate NaBO₂ · H₂ O₂ · 3H₂O, sodium percarbonate Na₂CO₃ · H₂O₂ · 0,5H₂O, hydrogen peroxide. Action of these bleaches is based on oxidation of painting substances due to allocation of active oxygen.

Optical bleaches (dyes) and blues (ultramarine, alyzarine paints) carry out completely other function.

If a body evenly reflects waves of all lengths of sunlight this body is represented to a human eye as white. But it is an ideal case. Even the bleached fabric has yellow shade. From the physical point of view it means, that the fabric reflects waves with the length corresponding to yellow color in greater degree, than other waves of sunlight. For this reason the fabric seems yellow.

The body seems white if it reflects 100 % of all waves at irradiation. On the contrary, the body seems black if it absorbs all beams. The body seems color if it absorbs waves of the certain length, and the reflected waves cause painting which is perceived by a human eye. The human eye perceives waves in length of 400-700 nanometers - seen light.

At improvement of whiteness degree by means of optical bleaches they absorb a part of the ultra-violet beams contained in daylight, and let out longer seen waves corresponding to blue-violet color. On yellow linen balance of all colors is established and the impression of white color turns out.

Efficiency of optical bleaches depends on several factors: efficiency of illumination, time of day and year, chemical structure. At artificial illumination their efficiency is much lower, than at daylight.

Requirements to optical bleaches:

1) Absence of substances harmful to an organism;

2) Stability at the presence of soap and synthetic detergents;

3) Good fastening on a fabric;

4) They should absorb ultra-violet light and radiate blue light at 440 nanometers;

5) Stability to light.

By manufacture of soap and synthetic detergents six basic classes of optical bleaches are applied (triazinilstilbens, aroilstilbens, benzidinsulphones, bisbenzimidazoles, triazole, aminokumarines).

Chemical bleaches interact with pollutions and transform them into such compounds which have not paint, they are colorless or have white color. Oxidizing bleaching has practical value due to free oxygen allocated as a result of reaction. For these purposes sodium perborate is used. Decomposition of sodium perborate in the alkaline environment occurs on the equations:

NaBO₂ · H₂O₂ · 3H₂O ↔ Na⁺ + BO₂^- + H₂O₂ + 3H₂O

H₂O₂ ↔ H⁺ + HOO^-

HOO^- ↔ OH^- + O*

2O* = O₂

Last reaction is the formation of molecular oxygen at temperatures above 40⁰С under action of catalytic quantities of iron and copper ions. This reaction reduces the bleaching action, but it may be slow down by introduction of stabilizers. As stabilizers magnesium silicate, ЭДТA are used. The optimum bleaching effect of sodium perborate is achieved at temperatures of washing above 60⁰С at presence of ЭДТА.

Except bleaching sodium perborate promotes formation of foam and at concentration more than 0,4 % give alkaline reaction with рН 9.

Except sodium perborate as bleaches are used sodium hypochlorite (NaOCl), lithium hypochlorite (LiOCl) and organic compounds containing nitrogen. The content of chemical bleaches can make up to 25 % from weight of washing substance.

Enzymes. Effective components for removal of painted spots of protein origin in compositions of synthetic detergents are enzymes. Enzymes are named the proteins possessing catalytic properties due to which in washing solution take place decomposition of protein pollutions as the result of their hydrolysis and they turn in water-soluble aminoacids and other compounds.

The content of enzymes in compositions of synthetic detergents makes 0,5-2 %. The most widespread enzymes are proteazes. These substances strengthen the washing action for account of enzyme hydrolysis; effectively destroy the stains from milk, blood, cocoa and other albuminous products. For removal of pollutions of fatty character other enzymes – lypaze - are used.

As thermal stability of enzymes is low, optimum temperature of their application makes 40-50⁰С. Enzymes find the basic application in structures powder synthetic detergents but can be used in washing pastes.

Regulators of medium. Action of washing substances, ability pentasodiumphosphate to form the complexes, antyresorb action of sodiumcarboxylmethilcellulose, biological activity of enzymes give the best effect in alkaline medium. For creation of alkaline medium inorganic salts are entered in structures of synthetic detergents. Carbonate, bicarbonate and silicates of sodium are concerned to regulators of medium.

Aromatic substances. Fragrant substances, essential volatile oils, various extracts and their mixes which are entered in structure of SD for giving aroma, refer to aromatizaters.

For production of aromatizaters are used the essential volatile oils, products of oil refining, coal, the wood industry, for example: lavender oil, extract of vervain, turpentine, synthetic alkanols, acids, simple and complex ethers, aldehydes and other classes of organic compounds.

Hydrotropic substances are components of SD which raise the solubility of SAS in water or water solutions of inorganic salts. The SAS solubility is increased because in this case the solvent is not only free water, but also hydrate water which is part of molecules. The most widespread hydrotropic substance is sodium toluolsulphonate. Hydrotropic additives reduce the viscosity of washing solutions, improve the flow ability of ready product, increase the productivity of dryers.