- Detergents are substances that help water cleanse things better by acting as wetting agents and emulsifying agents. There are two main types: soapless detergents made from petroleum and soaps made from animal fats or plant oils. - Detergents can harm the environment by depleting oxygen levels in water and promoting algal blooms, ultimately killing aquatic life. Their use also poses risks like potential skin irritation.

1. Lecture
on
Detergents and its Environmental
issues
1
By
Prof. Manorma Sharma & Lokesh Kumar Gupta
RKGITM

2. 2
Content
•What is detergent?
•Types of detergent
•Structure
•Preparation
•Properties
•Comparison of soap & soap less detergent
•Advantages and limitaions
•Environmental impacts
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3. WHAT IS A DETERGENT?
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A detergent is a surfactant or a mixture of surfactants with
cleansing properties in dilute solutions.
Detergents are the sodium or potassium salts of long chain
benzene sulphonic acids.

4. TYPES OF DETERGENTS
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There are two types of detergents:
Soapless detergents (or synthetic detergents)
Soapy detergents (or soaps)
Soapless Soapy

5. Soap less detergents
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They are also known as synthetic detergents.
Soapless detergent is a synthetic cleansing agent distilled from
petroleum-based and oil/fat-based substances.
Its chemical composition prevents the formation of soap scum
when combined with hard water.

6. Soapy detergents
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They are commonly known as soaps.
They are metal salts of long chain higher fatty acids.
They are prepared from vegetable oils & animal fats.
They cannot be used effectively in hard water due to the
formation of scum i.e. insoluble precipitates of Ca2+,
Mg2+
,
Fe2+
etc.

7. STRUCTURE OF DETERGENTS
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Detergents are usually sodium (or potassium) salts of long-
chain organic acids.
The detergent anion consists of two parts:
An ionic group (the‘head’)
A hydrocarbon chain (the‘tail’)

8. Structure of soapless detergent particles
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Two common soapless detergents are:
Sodium alkylbenzene sulphonate
Sodium alkyl sulphate

9. Structure of soap particles
9
Soaps are sodium (or potassium) salts of long-chain alkanoic
acids.
The ionic head of soaps is always a carboxylate group (–
COO−
).
A common soap is sodium stearate:
O and Na are not linked by covalent bond

10. PROPERTIES OF DETERGENTS
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WettingAgent
EmulsifyingAgent
CleansingAgent

11. Wetting Agent
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Water has a high surface tension.
A detergent reduces the surface tension of water.
So water spreads over the surface and wets it more easily.

12. EMULSIFYING AGENT
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Oil and water do not mix.
Oil-water emulsion is unstable.
So that after some time the tiny oil droplets rapidly join
together and grow larger to form a separate oily layer again.

13. 13
water
oil

14. CLEANSING ACTION
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Detergents are act as a cleansing agents.
They are surfactants (surface active agents).
 They work by reducing the surface tension of water,
enabling it to wet things more effectively, and by emulsifying
grease.

15. 15

16. PREPARATION OF DETERGENT
SOAP LESS DETERGENT
Synthetic detergents are prepared from hydrocarbons
obtained from petroleum.
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17. PREPARATION OF DETERGENT
SOAPY DETERGENT (SOAP)
Soaps are made from animal fats (e.g. beef and other fat) or
vegetable oils (e.g. palm oil and coconut oil etc).
Soaps are formed by the alkaline hydrolysis (breaking up) of
fats and oils by sodium or potassium hydroxide by boiling
under reflux conditions.
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18. This process is known as saponification.
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19. COMPARISON OF SOAP & SOAPLESS
DETERGENTS
SOAPY DETERGENTS SOAPLESS DETERGENTS
Soft water contains no or only
very small concentrations of
dissolved Ca2+
and/or Mg2+
ions.
They form lather only with
soft water.
In hard water it gives sticky
substance i.e. Scum
Hard water contains
appreciable concentrations of
Ca2+
and/or Mg2+
ions.
They form lather with soft and
hard water both.
No such formation occur.
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20. SOAPLESS DETERGENTS
Advantages Limitaions
They do not form scum with
hard water.
They are more soluble in
water.
They have a stronger cleansing
action.
They are derived from
petroleum. They save on
natural vegetable oils
They are non-biodegradable.
Thus they pose a danger to
aquatic life.
They are highly basic and
harmful to skin.
They cause conditions like
eutrophication.
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21. SOAPY DETERGENTS
Soaps are eco-friendly and bio
degradable.
They work very well in soft
water.
Non-toxic to aquatic life.
They are only mildly alkaline
Thus it seldom causes skin
allergy.
They derived from vegetable
oil and other natural
resources.
They do not work well in hard
water.
They form sticky scum.
They have weaker cleansing
properties than detergents.
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Advantages Limitations

22. ENVIRONMENTAL IMPACTS
Earlier detergents were non-biodegradable because they
contained branched hydrocarbon chains.
But now a days they are biodegradable in nature.
Still they affect environment (rivers & lakes) and human
beings-
Bacteria would use up dissolved oxygen in water.
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23. Plant nutrient (Phosphate) available in detergent supports the growth
of algae.
Ultimately it causes Eutrophication.
Loss of aquatic lives e.g. fishes
Most detergent solutions have pH values between 5 & 9.
Detergents with pH values outside this range may cause skin allergy.
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24. 24
ALGAL BLOOM DUE TO DETERGENTS

25. 25
SCUM FLOATING ON WATER BODY

26. 26
FISHES KILLED DUE TO DETERGENT WASTE

27. 27
SUMMARY
• A detergent is a substance which helps water to cleanse things
better.
• A detergent has cleansing properties.
• It acts as a wetting agent and an emulsifying agent.
• There are two types of detergents:
• Soapless detergents —petroleum products
• Soaps —animal fats or plant oils

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• Detergents are usually sodium (or potassium) salts
of long-chain organic acids.
• Soaps can be made by reacting animal fats or plant oils with
sodium hydroxide i.e. Saponification
fat / oil + sodium hydroxide → glycerol + soap
• Soft water contains no or only very low concentrations of
dissolved Ca2+
and/or Mg2+
ions.
• Hard water contains appreciable concentrations of
Ca2+
and/or Mg2+
ions.

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• Soaps work well in soft water but not in hard water.
• Soapless detergents work well in both soft and hard water.
• Problems associated with the use of detergents:
• Detergents may cause skin allergy.
• Detergents go down the drain into the sewage system and
eventually to rivers or seas.

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• Bacteria in water use up oxygen during the decomposition of
these detergents.
• This would kill aquatic lives.
• Many detergents contain phosphate additives. The phosphates
are nutrients for algae. This may lead to eutrophication and
death of aquatic lives.

31. REFERENCES
Katz David A. (2000);THE SCIENCE OF SOAPS AND
DETERGENTS.
src.gov.jm/wpcontent/uploads/.../soapanddetergents-
121119040041-phpapp01.ppt
www.chymist.com/Soap%20and%20detergent.pdf
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