Basic Soap and Detergent Chemistry

[togwt]

[A detergent is a surfactant or a mixture of surfactants having "cleaning properties in dilute solutions."Commonly, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water.] [1]



a) Hydrophilic ~ inorganic, water loving [: compounds that have an affinity to water and are usually charged or have polar side groups to their structure that will attract water]



b) Lipophilic (Hydrophobic) ~ organic, water hating [: compounds that are repelled by water and are usually neutral (no charge.)]



Surfactants have a polar group at one end (hydrophilic) and a non-polar group at the other end (lipophilic). The interaction of these two groups in water will reduce the surface tension of water. One end is inorganic and mixes with water, the other end is organic, and will dissolve other organic compounds; a detergent solution will dissolve both organic and inorganic soils



These terms have much to do with the structure of water itself. Water consists of two hydrogen atoms joined to one oxygen atom (H2O) all in a triangular pattern. The oxygen is negatively charged whilst the hydrogen end is positively charged. Thus, water molecules are actually attracted to each other and form hydrogen bonds.



Water is inorganic and anything that will mix with water is hydrophilic. Oil and anything that will mix with oil are hydrophobic, which is organic, so when water and oil are mixed they separate (See also Emulsion)



a) Soap refers to a liquid cleanser with a slightly acidic pH. (Typical car wash concentrates)



b) Detergents usually contain surfactants (laundry or specialist cleaners) although most car wash concentrates contain detergents



Surfactants perform other important functions in cleaning, such as loosening, emulsifying (dispersing in water) and holding soil in suspension until it can be rinsed away. Surfactants can also provide alkalinity, which is useful in removing acidic soils. Surfactants are classified by their ionic (electrical charge) properties in water: anionic (negative charge), non-ionic (no charge), cationic (positive charge) and amphoteric (either positive or negative charge).



Soap is an anionic surfactant. Other anionic as well as non-ionic surfactants are the main ingredients in today`s detergents. The chemistry of surfactants- soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids



I think this illustrates the importance of detailers understanding the ‘science’ of cleaning; and to this end it is helpful to have a basic knowledge of soap and detergent chemistry and what is needed to achieve effective cleaning



Water



The liquid solvent most commonly used for cleaning, has a property called surface tension. In the body of the water, each molecule is surrounded and attracted by other water molecules. However, at the surface, other water molecules only on the waterside surround those molecules. A tension is created as the water molecules at the surface are pulled into the body of the water. This tension causes water to bead up on surfaces (glass, fabric), which slows wetting of the surface and inhibits the cleaning process.



You can see surface tension at work by placing a drop of water onto a counter top. The drop will hold its shape and will not spread. In the cleaning process, surface tension must be reduced so water can spread and wet surfaces. Chemicals that are able to do this effectively are called surface-active agents, or surfactants. They are said to make water "wetter."



Fats and Oils



The fats and oils used in soap making come from animal or plant sources. Each fat or oil is made up of a distinctive mixture of several different triglycerides. In a triglyceride molecule, three fatty acid molecules are attached to one molecule of glycerine. There are many types of triglycerides; each type consists of its own particular combination of fatty acids. Fatty acids are the components of fats and oils that are used in making soap.



They are weak acids composed of two parts: A carboxylic acid group consisting of one hydrogen (H) atom, two oxygen (O) atoms, and one carbon (C) atom, plus a hydrocarbon chain attached to the carboxylic acid group. Generally, it is made up of a long straight chain of carbon (C) atoms each carrying two hydrogen (H) atoms.



Phosphates



Sodium tripolyphosphate (STPP) is an ingredient use to enhance the performance capabilities of automatic dishwasher detergents. They contribute buffering strength, sequestering (or chelating) power, dispersion and absorptive capabilities, and solubility. They not only strip food and grease from dishes but also prevent food debris becoming reattached during the wash.



While phosphates are no longer permitted in laundry detergents in the US, because the chemical compounds also pollute lakes, bays and streams as they create algae blooms and starve fish of oxygen. They are still allowed in automatic dishwashing soaps (some states differ on the legally acceptable levels). Phosphates are additives that fight the effects of the minerals found in tap water--the minerals that cause hard water and the related spotting on dishes.



The problem is that without phosphates cooking pots and pans turn grey, aluminium starts to turn black, the glasses have fingerprints and lip prints still on them, and they take on a ‘powdery’ look to them.





Enzymes



Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates sufficient for life. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.



Like all catalysts, enzymes work by lowering the activation energy for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions.



Catalyst



A catalyst works by lowering the activation energy for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most reaction rates are millions of times faster than those of comparable un-catalyzed reactions. A catalyst is not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions.



Controlling pH



Commonly used chemicals include sodium hydroxide a caustic metallic base. It is used in many industries, mostly as a strong chemical base in the manufacture of soaps and detergents; it is often used to increase the alkalinity of a mixture, or to neutralize acids



Alkali



An alkali is a soluble salt of an alkali metal like sodium or potassium. Originally, the alkalis used in soap making were obtained from the ashes of plants, but they are now made commercially. Today, the term alkali describes a substance that chemically is a base (the opposite of an acid) and that reacts with and neutralizes an acid. The common alkalis used in soap making are sodium hydroxide (NaOH), also called caustic soda; and potassium hydroxide (KOH), and also called caustic potash.



Chelators



Are used in chemical analysis, as water softeners, and are ingredients in many commercial products. Citric acid is used to soften water in soaps and laundry detergents.



How Soaps are made



Soaps are mixtures of sodium or potassium salts of fatty acids, which can be derived from oils or fats by reacting them with an alkali (such as sodium or potassium hydroxide) in a process known as saponification.



Saponification of fats and oils is the most widely used soap making process. This method involves heating fats and oils and react them with a liquid alkali to produce soap and water (neat soap) plus glycerine. The other major soap making process is the neutralization of fatty acids with an alkali. Fats and oils are hydrolyzed (split) with a high-pressure steam to yield crude fatty acids and glycerine. The fatty acids are then purified by distillation and neutralized with an alkali to produce soap and water (neat soap).



When the alkali is sodium hydroxide, sodium soap is formed. Sodium soaps are "hard" soaps. When the alkali is potassium hydroxide, potassium soap is formed. Potassium soaps are softer and are found in some liquid hand soaps and shaving creams. The carboxyl ate end of the soap molecule is attracted to water. It is called the hydrophilic (water-loving) end. The hydrocarbon chain is attracted to oil and grease and repelled by water. It is known as the hydrophobic (water-hating) end.



How Water Hardness Affects Cleaning Action



Although soap is a good cleaning agent, its effectiveness is reduced when used in hard water. Hardness in water is caused by the presence of mineral salts - mostly those of calcium (Ca) and magnesium (Mg), but sometimes also irons (Fe) and manganese (Mn). The mineral salts react with soap to form an insoluble precipitate known as soap film or scum. Soap film does not rinse away easily. It tends to remain behind and produces visible deposits on clothing and makes fabrics feel stiff. It also attaches to the insides of bathtubs, sinks and washing machines.



Reacting with hard water minerals to form the film uses up some soap. This reduces the amount of soap available for cleaning. Even when clothes are washed in soft water, some hardness minerals are introduced by the soil on clothes. Soap molecules are not very versatile and cannot be adapted to today`s variety of fibres, washing temperatures and water conditions.



Surfactants in detergents



Notice that surfactants actually reduce the surface tension of water by a factor of three or more. A detergent is an effective cleaning product because it contains one or more surfactants. Because of their chemical makeup, the surfactants used in detergents can be engineered to perform well under a variety of conditions. Such surfactants are less sensitive than soap to the hardness minerals in water and most will not form a film. Detergent surfactants were developed in response to a shortage of animal and vegetable fats and oils during World War I and World War II. In addition, a substance that was resistant to hard water was needed to make cleaning more effective. At that time, petroleum was found to be a plentiful source for the manufacture of these surfactants.



Surfactants are common to both washing-up liquids and car care products; namely Sodium laureth sulphate, or sodium lauryl ether sulphate (SLES) a foaming agent, Dodecylbenzene sulphonic acid (neutralised with Sodium Hydroxide, Triethanolamine or Isopropanolamine)

.

Detergent surfactants are made from a variety of petrochemicals (derived from petroleum) and/or oleo chemicals (derived from fats and oils). Petrochemicals and Oleo chemicals like the fatty acids used in soap making, both petroleum and fats and oils contain hydrocarbon chains that are repelled by water but attracted to oil and grease in soils.



These hydrocarbon chain sources are used to make the water-hating end of the surfactant molecule. Other Chemicals, such as sulphur trioxide, sulphuric acid and ethylene oxide, are used to produce the water-loving end of the surfactant molecule.



Foaming agents, emulsifiers, and dispersants are all surfactants which suspend respectively, a gas (air) an immiscible liquid, or a solid in water or some other liquid. Although there is similarity in these functions, in practice the surfactants required to perform these functions differ widely. In emulsification, as an example - the selection of surfactant or surfactant system will depend on the materials to be used and the properties desired in the end product. An emulsion can be oil droplets suspended in water, oil in water emulsion, water suspended in a continuous oil phase, or a mixed emulsion. The surfactants form what amounts to a protective coating around the suspended material, and these hydrophilic ends associate with the neighbouring water molecules.



Solubilisation - is a function closely related to emulsification. As the size of the emulsified droplet becomes smaller, a condition is reached where this droplet and the surfactant micelle are the same size. At this stage, an oil droplet can be imagined as being in solution in the hydrophobic tails of the surfactant and the term solubilisation is used. Emulsions are milky in appearance and solubilised oils, for example - are clear to the eye.



Detergency- the function of detergency or cleaning is a complex combination of all the previous functions. The surface to be cleaned and the soil to be removed must initially be wet and the soils suspended, solubilised, dissolved or separated in some way so that the soil will not just re-deposit on the surface in question



All surfactants have the following features: they make the removal of dirt easier by reducing the surface tension between the water and the paint surface, they produce foam, and this foam suspends dirt and stops it from being re-deposited.



There are surfactants that use Marangoni stress to prevent droplet formation, Since a liquid with a high surface tension pulls more strongly on the surrounding liquid than one with a low surface tension, the presence of a gradient in surface tension will naturally cause the liquid to flow away from regions of low surface tension so that water drains from the surfaces in thin sheets, rather than forming droplets, its drawback is that it leaves a thin film on the dried surface.



The benefits of using it are that it prevents "spotting" caused by droplets of water drying and leaving behind dissolved lime scale minerals, and can also improve drying performance as there is less water remaining to be dried its drawback is that it leaves a thin film on the dried surface.



Emollients



Dishwashing detergents contain emollients; an ingredient designed to protect a person`s hands, by keeping them soft and prevent cracking and drying. However emollients make the paint surface more difficult to dry and leave an oily residue. Diethanolamides are to act as foaming agents or as emulsifiers



Emollients have three basic properties:



1. Occlusion - providing a layer of oil on the surface of the skin to slow water loss and thus increase the moisture content,



2. Humectants - increasing the moisture-holding capacity of the stratum



3. Lubrication - adding slip to glide across the skin (although not good for car washing as it leaves a film)



Optical Brightener



[: are dyes that absorb light in the ultraviolet and violet region (usually 340-370 nm) of the electromagnetic spectrum, and re-emit light in the blue region (typically 420-470 nm)]



Brighteners (Triazine-stilbenes, one of several available optical brightening agents (OBAs)) that were commonly added to laundry detergents to replace whitening agents removed during washing and to make the clothes appear cleaner. Brighteners can be enhanced with the addition of certain polyols like high molecular weight polyethylene glycol or polyvinyl alcohol. These additives increase the visible blue light emissions significantly. Optical brighteners have replaced bluing which was formerly used to produce the same effect. Some brighteners can cause allergic reactions when in contact with skin, depending on the individual.



Something that is really clean shouldn’t be an optical illusion; optical brighteners are synthetic chemicals that make fabrics appear to glow in the presence of ultraviolet light. They don`t have anything to do with getting things clean -- they`re only added to detergents to make us think our laundry is brighter and whiter than it really is. These agents absorb ultraviolet light and emit it back as visible blue light.



Optical brighteners are actually ultraviolet dyes that may be invisible under many lighting conditions; for an optical brightener to work properly it must be exposed to ultraviolet light usually from sunlight; thus, they’re not of much value if the light falling on the treated surface is mainly incandescent (light bulbs).

There are additional potential problems with the use of optical brighteners; one is these i tendency to yellow with age, which is one of the reasons that carpet and furniture manufacturers discourage its use. This chemical is not biodegradable and can pass through waste-water treatment plants and endanger aquatic plants and fish.



Cloud Point



[:The cloud point of a non-ionic surfactant solution is the temperature where the mixture starts to phase separate and two phases appear, thus becoming cloudy] [1]



The temperature at which a surfactant becomes insoluble in water; this becomes important when designing detergents for use in hot water



How Detergent Surfactants Are Made Anionic Surfactants



The chemical reacts with hydrocarbons derived from petroleum or fats and oils to produce new acids similar to fatty acids. A second reaction adds an alkali to the new acids to produce one type of anionic surfactant molecule. First converting the hydrocarbon to an alcohol and then react with the fatty alcohol with ethylene oxide produce non-ionic surfactants non-ionic surfactant molecules. These non-ionic surfactants can be reacted further with sulphur containing acids to form another type of anionic surfactant.



How Soaps and Detergents work



Soap is usually a blend of several surfactants, which are two opposing polar groups, hydrophilic and a non-polar group lipophilic. The interaction of these two groups in water will reduce the surface tension of water from 72 to 35 dynes/cm soap creates foam by trapping air inside, which is about 95% air and 5% soap / water, this foam has no affect on its cleaning ability. The/surfactants use emulsification to dissolve and encapsulate oily particles and that reduces the amount of active surfactants left in the bucket. So if the surface is very oily, you will see a substantial drop in the suds and therefore a reduction in its cleaning ability.



These types of energy interact and should be in proper balance. Let`s look at how they work together. Let`s assume we have oily, greasy soil on clothing. Water alone will not remove this soil. Nearly all compounds fall into one of two categories: hydrophilic (`water-loving`) and hydrophobic (`water-hating`). Water and anything that will mix with water are hydrophilic. Oil and anything that will mix with oil are hydrophobic. When water and oil are mixed they separate.



Hydrophilic and hydrophobic compounds just don`t mix. These opposing forces loosen the soil and suspend it in the water. Warm or hot water helps dissolve grease and oil in soil.



Washing machine agitation or hand rubbing helps pull the soil free. The cleansing action of soap is determined by its polar and non-polar structures in conjunction with an application of solubility principles.



One important reason is that oil and grease present in soil repel the water molecules. Now let`s add soap or detergent. The surfactant`s water-hating end (lipophilic) is repelled by water but attracted to the oil in the soil.



At the same time, the water-loving end (hydrophilic) is attracted to the water molecules.



Back when laundry was done with soap flakes, suds level was an indicator of cleaning performance. So, many people today think that a good rich level of suds is necessary for clean laundry. However, this is no longer true. Today`s detergents are formulated to have any suds level desired without affecting cleaning performance. "They make the removal of dirt easier by adding surfactants that reduce the surface tension between the water and the paint surface.



In reality suds (a chemical foaming agent - Diethanolamides or Sodium laureth sulphate or sodium lauryl ether sulphate) do absolutely nothing to clean, they are simply a structure that a portion of the solution had taken due to being mixed with air; they still contain the same ratio of soap. They are however, a good indicator of the amount of active soap in the solution.



The amount of foaming produced has nothing to do with its cleaning efficiency (although it does provide a means of encapsulation as well as acting a cushion between the paint surfaces and cleaning tool) They are there simply because we are so engrained with the idea that soap suds do the cleaning that it is impossible to use anything else.



In almost all detergents the suds are made by a foaming agent, not by the cleaning agents in the detergent. In fact, industrial cleaners usually have no foaming agents and specialized users do not want suds. Think of a hand degreaser, or rinse less car washes (ONR) there are no suds yet it sure does the job



Car Wash Concentrates



A good quality car wash (Zaino Z-7™ Show Car Wash or Griot’s Car Wash) provides a slightly alkaline pH-8 and balanced blend of active biodegradable ingredients, to provide lubrication to prevent scratching, to lift and encapsulate dirt, road grime and oils.



Washing-up Liquids (Detergent)



The use of this type of detergent has been debated for years among car detailing enthusiasts. Problems arise when people use dish washing liquid as their normal car wash soap. From a chemical standpoint using dishwashing detergents to clean a porous, sensitive clear coat paint surface is very poor choice.



Notable brands of dishwashing liquid include Procter & Gamble’s Dawn®, which is the leading brand in the United States, and ````` Liquid, which is the bestselling brand in the United Kingdom and similar type dish washing liquids chemistry relies primarily on detergent and surfactant technology. This type of chemistry has advanced to the point that it can be engineered to specific soils (i.e. organic grease)



Detergent and soap chemistry and product formulation is a lot more complicated than this, suffice it to say; modern car wash formulations are automotive soil specific. As a means of paint surface preparation and the removal of wax / polymer sealants it’s not very effective as paint protection products are usually formulated to be detergent resistant



It was initially used by body shop detailer’s to remove traces of the oils from waxes commonly used on Nitrocellulose Lacquer paints, this is probably the reason some long established painters recommend its use a paint preparation product prior to using their sealants. (As Confucius didn’t say; “plus ca change plus ca reste la même chose.�)



Advanced auto wash concentrates and paint cleaners are available and are better suited to cleaning paint surfaces. Modern clear coat is porous so I would not recommend using a harsh dishwashing detergent such as Dawn® on a regular basis, as they contain both sodium and a degreaser, although most of them are approx pH 8.0 (although pH is not the only thing to consider when evaluating products, the MSDS will provide other relevant information.



The MSDS indicates that this product contains Sodium laureth sulphate a foaming agent, Dodecylbenzene sulphonic acid and sodium hydroxide; these salt crystals could be mildly abrasive when they `come out` of the compound later and will then permeate the pant surface. Salt is hygroscopic and highly alkaline, the same ingredient are used in engine degreasers to chemically ‘burn’ hydrocarbon oils and grease from engine surfaces. Sodium hydroxide will severely stain aluminium, magnesium, etc other ingredients and will tend to oxidise the paint system and emulsify, breakdown and leach out oils found in rubber moulding, trim and the paint system, which causes the plasticizers to dry out causing them to lose their flexibility and eventually fail.



Dishwashing detergents contain emollients; an ingredient designed to protect a person`s hands, by keeping them soft and prevent cracking and drying. However emollients make the paint surface more difficult to dry and leave an oily residue.



Emollients have three basic properties: Occlusion - providing a layer of oil on the surface of the skin to slow water loss and thus increase the moisture content, Humectants - increasing the water-holding capacity of the stratum and Lubrication - adding a slip or glide across the skin. Generally you should avoid the use of household cleaning products for automotive detailing as they are formulated for an entirely different type of cleaning.



[Your car surface and the dirt that gets on it are a lot different from the food soils and dishes that dishwashing liquids clean effectively. We don`t recommend them for cleaning your car] Proctor and Gamble



See also FAQ Proctor and Gamble website - FAQ



Water quality



Such as pH values, mineral content, harness, etc surfactants used and other characteristics will affect how well a car wash concentrate works. As well as conditioners to maintain the shine without stripping the paint of essential oils (the way detergents do) and dispersing them in the rinsing process, warm water (not hot) will improve the cleaning abilities of wash concentrates.



The amount of foaming produced has nothing to do with its cleaning efficiency (although it does provide a means of encapsulation as well as acting a cushion between the paint surfaces and cleaning tool) when laundry was done with soap flakes; suds level was an indicator of cleaning performance. Many people still equate a good rich level of suds with cleaning; however, this is no longer true. Today`s quality car wash concentrates are formulated with anionic surfactants that have a very low suds level without affecting cleaning performance. One of the advantages of this formulation is that road dirt and grime are encapsulated in its structure (micelles), which makes for very easy and efficient rinsing.



The harsh detergents found in some car wash soaps contain sodium silicate or sodium hydroxide may etch the surface of the clear-coat leaving white residue or dulling the entire finish. Car wash concentrates that contain a high foaming (suds) agent can be corrosive, if sodium (salt) is used as an agent to create the foaming. The usual dilution is l oz per two gallons water (using a lesser dilution will leave a film on the paint surface) Avoid products that contain harsh detergents as they will emulsify and leach out any oils or waxes that provide protection and/or flexibility (See also Alkalinity, pH Values, Hard Water, Water Filtration)





[Edit: Cloud Point revised 01/30/2011]

[gutierrezcl]

Stumbled on this post when doing a search. Congrats to the OP, great info!



Sent using Tapatalk

[togwt]

Thank you...





Within these articles you’ll discover the ‘How’ and ‘Why’ and find pretty much everything you need to know about detailing; if you do your research correctly.



TOGWT® Autopia Detailing Wiki - http://www.autopia.org/forum/autopia...yperlinks.html



I hope the information in these articles is of some help to you. If you have any further questions please let me know

[SATracker]

Great write-up, as is your usual practice; I now have a headache, remembered why I flunked chemistry.

[Ron Ketcham]

And if the chosen car wash soap is not thick enough or enough "foam", just throw in a a couple of table spoons of table salt into the bottle before you start to dilute it with water.

Cleans more, but leaves a film, but "foam" is what everyone thinks is so important.

Grumpy