The word Surfactant is an abbreviation, a shortened way to explain “surface-active agent.” Surfactants are typically products made up of molecules containing a hydrophilic, or “water-loving” end, plus a hydrophobic, or “water-fearing” end. Surfactants are molecules that have the ability to adsorb at the interfaces between two phases (e.g. air–water, oil–water or liquid–solid), thus lowering the interfacial tension and stabilising the interface. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.

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Review about Surfactant
Reviewed by:
Zubayar Rahman
Department of Pharmacy
University of Asia Pacific

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Content
Topic Page
Surfactant 3
Classifications of Surfactants 3-8
Applications 9-11
Environmental considerations 11

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Surfactants
The word Surfactant is an abbreviation, a shortened way to explain “surface-active agent.”
Surfactants are typically products made up of molecules containing a hydrophilic, or “water-
loving” end, plus a hydrophobic, or “water-fearing” end. Surfactants are molecules that have
the ability to adsorb at the interfaces between two phases (e.g. air–water, oil–water or liquid–
solid), thus lowering the interfacial tension and stabilising the interface. Surfactants may act
as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
Surfactants are typically going to be dissolved in to something to do a specific job, or play a
certain “role” so that when the surface tension is reduced or broken, the function will be either
completed, or be easier to complete. They are used in a plethora of applications and
products. Surfactants are everywhere, and play such a large role in products we have around
us daily. When we wake up in the morning they are in our soaps and facial cleansers, our
shampoos, shaving creams, and even our toothpaste when we brush our teeth. Surfactants are
in hard surface cleaners we use to wash our countertops; in the car wash soaps we use. They
are in the insect repellents and sun screen sprays that protect us when we play outside.
Surfactants are in all kinds of commercial and industrial products too. Surfactants are a main
constituent in paints and coatings and adhesives. Just about anything you can think of that is
sprayed on, applied, brushed on, wiped on, smeared on probably has some form of surfactant
in the formulation.
Surfactants can be broken down into three types:
Lipophilic: is Oil Loving
Hydrophilic: is water loving
Hydrophobic: is water hating. They repel water
Types/ Classifications of Surfactants:
Surfactants have what many term an “electrical charge” on the water-loving (hydrophilic) end
of the molecule, that distinguishes between the different types of surfactants. Based on this
“charge” there are four different, further categories, these are: Anionic, Non-ionic, Cationic
and Amphoteric. Again, we are not only dividing the surfactants by the charge, but we are
listing them in order of tonnage produced/ usage / popularity.

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Anionic
Anionic surfactants contain anionic functional groups at their head, such as sulphate, sulfonate,
phosphate, and carboxylates. Prominent alkyl sulphates include ammonium lauryl sulphate,
sodium lauryl sulphate (sodium dodecyl sulphate, SLS, or SDS), and the related alkyl-ether
sulphates sodium laureth sulphate (sodium lauryl ether sulphate or SLES), and sodium myreth
sulphate etc.
The anionic surfactants possessing a negative charge on their hydrophilic end, charge helping
the surfactant molecules interact with soil particles, lifting and suspending soils in “bubble-
like” arrangements called micelles. Generally, they are great foamers, but they do not tend to
not be as good at emulsifying oily soils as some other surfactant types.
In personal care the anionic are really widely used, probably the most common. You can easily
recognize them – sodium lauryl sulphate, ammonium sulphate etc… They are widely used in
personal care because they are good foamers, clean well, and are for the most part affordable.
They make good shampoos, body washes, etc. They also do well in formulations where there
are other typical soap making chemicals like fatty acids, lye etc.
Some people report that anionic are irritating to their skin. This is of course due somewhat to
their efficient foaming and cleaning. The use or overuse of anionic like sodium lauryl sulphate
in soaps that are used often will increase sensitivity so if you are using an anionic surfactant
minimize it in the formulation and add another effective but less irritating surfactant as a co-
surfactant to make the product have less potential to irritate the skin, maybe a suitable
amphoteric like cocamidopryl betaine for example.
When reading a list of ingredients on your cleaning products, you can usually identify the
anionic surfactants as those that have the following in their names:
▪ Sodium
▪ Sulfonate
▪ Ammonium
▪ Magnesium
▪ Sulfonate/ Sulphate

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(For example, sodium lauryl sulphate (SLS) liquid and the SLS powder, Sodium lauryl
sulfoacetate (SLSa), ammonium sulphate, sulfosuccinates, sarcosinates, isethionates, and
taurates, sodium gluconate are all anionic surfactants)
Production wise Anionic surfactants account for about 50 % of the world production.
Non-ionic
Non-ionic Surfactants are next. They do not ionize (thus non-ionic) in aqueous solution,
because their hydrophilic group is of a no dissociable type, such as alcohol, phenol, ether, or
amide. A large group of the non-ionic surfactants are made hydrophilic (water loving) by the
presence of a polyethylene glycol chain (PEG), obtained by the addition of ethylene oxide
(EO). They are called polyethoxylated non-ionic. Popular types in this group are nonyl phenol
ethoxylates, alcohol ethoxylates.
Ethoxylated non Ionics are very useful in many poplar applications like washes and cleansers.
Since they are ethoxylated, and by the ethoxylation, like the PEGS, they are made more water
loving or hydrophilic. So with the hydrophilic end this makes many of the non-ionic excellent
solubilizes to get many different types of products to blend together – like fragrance oils that
are not so water friendly to blend in to water based formulations. They can also help blend
dissimilar products in to formulations that are not water based, but oil based.
As far as the lipophilic group is concerned, it is often of the alkyl or alkyl benzene type, the
former coming from fatty acids of a natural origin. The addition of propylene oxide produces
a polyether which is slightly hydrophobic. These are called polyEO polyPO block copolymers,
which are most often included in a different class, e.g. polymeric surfactants. Cleaning and
usage wise – these are typically good at cleaning particles grease and dirt easily and are usually
not as expensive as some other types/ classes of surfactants.
In the past 20 years or so glucoside (sugar based) groups, have been introduced in the market,
and have become very popular because of their low toxicity, and for the fact that they are seen
as more environmentally friendly being from renewable resources like corn sugars. These
glucosides are sometimes called alkyl polyglucosides, or just polyglucosides. Some very
popular ones are Decyl glucoside, coco glucoside, lauryl glucoside. There are also some
popular blends of the glucosides, or that use a glucoside as a main or co-surfactant. One very

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popular blend featuring decyl glucoside ( a good foamer) as a co – surfactant blended in with
another non-ionic the sodium lauryl lactylate which offers unsurpassed skin moisturizing, and
a smooth feel when applied- the blend is often called polyglucose / lactylate blend, with the
INCI: Decyl Glucoside (and) Sodium Lauryl Lactylate. Try it for a new cleanser. It is a great
performer.
Some non-ionic are high foamers (most are not), like the anionic, while others Amy not
generate much foam. Because of their lower foam profile and strong emulsifying potential,
these surfactants are the preferred choice when formulating many types of cleaners – from
degreasers, to spot cleaners. And many are used in personal care (Not the nonyl phenol type
though)
Unlike anionic surfactants, non-ionic are typically, undiluted, thick liquids
Some particular types of Non-ionic surfactants include:
* Polysorbates
* Ethoxylates (nonyl phenol and others)
* Alkoxylates (alcohol ethoxylates)
* Glucosides /Alkyl PolyGlucosides
* Cocamide
Non-ionic surfactants are probably the most useful surfactants for formulators of products if
you consider ease of use, cleaning ability and effectiveness. However, remember most non-
ionic do not foam as well and may not have good foam stability. Which is why they are usually
blended with surfactants from other families “ or types, like blending with an amphoteric like
cocamdiopropyl betaine for example.
About 45% of the overall industrial production of all Surfactants Are Non-ionic.

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Cationic
Cationic Surfactants are dissociated in water into an amphiphilic cation and an anion, most
often of the halogen type. A large portion of this class corresponds to nitrogen compounds such
as fatty amine salts and quaternary ammoniums, with one or several long chain of the alkyl
type, often coming from natural fatty acids. These surfactants are in general more Anion:
negatively (-) charged ion which moves toward anode during electrolysis. Cation: positively
(+) charged. These surfactants – tend to be more expensive than anionic, because of the
expensive ways they are made – synthesis. They are often used mainly in two areas – 1) as
bactericides (and a sub category – the antistatic agents,) 2) as positively charged substance like
in corrosion inhibition. They are less common in cleaners
They are also found in many disinfecting hard surface cleaners since they do have antimicrobial
characteristics.
Cationic are not found as often as other surfactants in personal care, but they have their place.
They are often well suited in formulations where you need a surfactant but foaming is not the
reason it is needed. Sometimes cationic have other purposes besides foaming. Cationic are
often used for softening and for their ability to work with other ingredients. A good example
of where you may see a cationic surfactant is in a hair conditioner. The cationic are compatible
with amphoteric and non-ionic surfactants will be compatible with cationic surfactants.
However, because of the opposing charge cationic (positive) and anionic (negative) surfactants
do not work together and will become a “goo” if combined.”
A few common cationic surfactants used in bath and body recipes are your chlorides, the
benzalkonium, centrimonium, stearalkonium chlorides. Many common cationic surfactants are
irritating to the skin so limit the use to just what is necessary.
Cleansers containing cationic surfactants cannot be mixed with those containing oppositely
charged anionic surfactants. The molecules would interact with each other, producing a gooey
mess that drops out of solution.
When reading ingredients lists, look for the words “chloride” or “bromide” (as in alkyl benzene
ammonium chloride, and the chlorides methioned above) to identify cationic.

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Amphoteric (or Zwitterion)
When a single surfactant molecule exhibit both anionic and cationic dissociations it is
called amphoteric (or zwitterion). Amphoteric surfactants, our final type of surfactant, may be
the least used overall (they are used a lot in personal care products though) and least talked
about surfactants but they are very useful in certain products and applications.
Amphoteric surfactants have little use on their own, but work extremely well in enhancing the
cleaning and foaming effect of both anionic and non-ionic surfactants. They can serve as
“coupling agents,” which hold the formulation’s surfactants, solvents and the inorganic salt
components together.
Amphoteric are usually named in a way that easily indicates they are amphoteric, as in the trade
name “Amphoterge.”
Other examples of amphoteric are betaines (cocamidopropyl betaine ) and amine oxides.
Most amphoteric surfactants are sensitive to pH, whereas they are cationic at low pH and
anionic at high pH, with an amphoteric behaviour at their intermediate ph.
In personal care products, amphoteric like cocamidopropyl betaine are commonly used
and often blended in with non-ionic and anionic. If you see a product like a sodium lauryl
sulphate or sodium lauryl ether sulphate, you will often also see the co-surfactant as
cocamidopropyl betaine or lauramidopryl betaine (or both) . This type of blend works well
because you get the foaming, the cleansing, but the overall harshness of the anionic have been
“balanced” with the amphoteric so the product has been made to be an efficient cleanser and
not as harsh as the anions used alone.
Some amphoteric surfactants are more expensive versus the non-ionics and anionic, and
consequently, their use may be limited to special applications such as cosmetics and high
quality cleaners where their high biological compatibility and low toxicity is of primary
importance.

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Applications:
Laundry detergents
A detergent is made up of many ingredients, some of which are surfactants. An example of the
mixture of compounds in a detergent is shown in Table 1.
In this formulation there are seven surfactants, two anionic, three non-ionic and two soaps.
However, there are other ingredients, each with specific functions:
Bulking agents, such as sodium sulphate and water.
Some detergents need anti-caking agents, for example aluminium silicate, which keep the
powder dry and free-flowing.
Builders, usually sodium alum inosilicates, a type of zeolite, remove calcium and magnesium
ions and prevent the loss of surfactant through scum formation.
Stains can be bleached with oxidizing agents such as sodium perborate (NaBO3.4H2O) and
sodium per carbonate (2Na2CO3.3H2O2) which react with hot water to form hydrogen peroxide
which in turn reacts with the stain.
However, bleach activators are needed for low temperature washes. Sodium perborate and sodium per
carbonate do not liberate hydrogen peroxide in cool water. A compound is added to react with them to
liberate a peroxycarboxylic acid, RCO3H, which oxidizes stains readily.
Other ingredients which can be added to a detergent include:
Buffering agents - to keep the pH at the appropriate value
Structures - to give shape to the fabric being washed
Sequestrates - to react with free metal ions which might otherwise cause problems with
appearance or scum formation
Optical brighteners - to make the fabrics look brighter and whiter
Antifoaming agents

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Enzymes - to remove specific stains: proteases (to remove proteins), amylases (to remove
starches), lipases (to remove fats)
Fragrance
Anti-redeposit ion agents - to prevent dirt being redeposited on fabrics
Skin conditioning agent - to help to keep the skin in good condition
Softness extender - to help keep the clothes 'soft'
Emulsifier - to help keep immiscible liquids as an emulsion
Colorant
Domestic automatic machine laundry liquids are formulated using blends of anionic, non-ionic
and soap surfactants and various other functional substances. Bleach systems are not
compatible with the higher water temperature and cannot be used above ca 315 K.
For hand washing (used for delicate fabrics such as wool or silk), foam-stabilisers are included,
to maintain foam. The customer equates the quantity of foam produced with the detergent
cleansing action. For the quantity of foam produced the order is:
anionic > soap > non-ionic > cationic
Machine dishwashing powders and tablets
The products used in dishwashers are usually powders and contain builders (90-95%), a non-
ionic surfactant (1-5%), bleach agents with an activator and enzymes. They are formulated with
sodium carbonate and sodium silicate to create a very alkaline environment that helps to
denature (break down) the fats and proteins left on the used dishes and utensils.
Washing up liquids
These formulations contain between 13-40% of surfactants which are predominantly alkyl
ether sulphates but also include non-ionic and amphoteric (betaines).

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Shampoos and shower gels
These tend to be based on alkyl ether sulphates and usually contain small amounts of other
surfactants (most typically amphoteric) which help protect the skin from irritation and also
condition the hair.
Hair conditioners and fabric softeners
These products are formulated using cationic surfactants (sometimes combined with small
amounts of non-ionic surfactants). These are not cleansing products and the cationic surfactant
is deposited onto the slightly negatively charged hair or cotton fibre surface, thus giving a
lubrication benefit.
Environmental considerations
In Western Europe all surfactant components of domestic detergents must be biodegradable.
This requirement resulted from the fact that the original alkyl benzene sulfonate anionic were
based on branched alkenes and these proved resistant to degradation by bacteria at sewage
treatment works causing many rivers to suffer from foam. There was also a fear that surfactants
could be "recycled" into drinking water. Similar concerns were expressed about nonylphenol
ethylates and so in the 1980s the industry moved to linear alkyl benzene sulfonates and alcohol
ethoxylates as the major ingredients of their formulations. Effective sewage treatment ensures
that detergent components which are part of household effluent water are not discharged
untreated into rivers and water courses.
The development of compact powders and liquids and refillable packages is designed to reduce
packaging waste.
Redesign of washing machines and laundry detergent products (including the addition of
bleach activators and enzymes to ensure good stain removal at low temperatures) has resulted
in energy savings by reducing water heating and using shorter wash cycles.

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Reference:
1. https://en.wikipedia.org/wiki/Surfactant
2. https://www.britannica.com/science/surfactant
3. http://www.essentialchemicalindustry.org/materials-and-applications/surfactants.html
4. https://www.chemicalsafetyfacts.org/surfactants/
5. https://www.stevenabbott.co.uk/practical-surfactants/surfactant-types.php
6. http://ingredientsshop.com/surfactant-types-uses-ways-use-effectively/