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T ERM PAPER

OF

CHE-101

TOPIC:- EXPLAIN SURFACTANTS.

SUBMITTED BY SUBMITTED TO

NAME- BITTU KUMAR LECT. JYOTI MAM

SECTION-E2801 (DEPARTMENT OF CHEMISTRY.)

ROLL NO. – A05

REGISTRATION NO. -10808479

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ACKNOWLEDGEMENT

As usual a large number of people deserve my thanks for the help

they provided me for the preparation of this term paper.

First of all I would like to thank my teacher Lect. Jyoti mam for her

support during the preparation of this topic. I am very thankful for her

guidance.

I would also like to thank my friends for the encouragement and

information about the topic they provided to me during my efforts to

prepare this topic.

At last but not the least I would like to thank seniors for providing me

their experience and being with me during my work.

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-:TABLE OF CONTENTS:-

1.1 INTRODUTION

1.2 PROPERTIES

1.3 TYPE OF SURFCATANTS

1.3.1 ANIONIC SURFACTANTS

1.3.2 CATIONIC SURFCTANTS

1.3.3 NONIONIC SURFACTANTS

1.3.4 AMPHOTERIC SURFACTANTS

1.4 APPLICATION OF THE SURFACTANTS

1.5 HARMFULL EFFECT OF SURFACTANTS

1.6 REFERENCES

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1.1 INTRODUCTION:-

The term surfactant (short for surface-active-agent) designates a substance which exhibits some superficial Surfactants provide remarkable benefits in many textile wet processes. A surface active chemical is one which tends to accumulate at a surface or interface. An interface is the area of contact between two substances.

The surface tension of a liquid is an internal pressure caused by the attraction of molecules below the surface for those at the surface of a liquid. This molecular attraction creates an inward pull, or internal pressure, which tends to restrict the tendency of the liquid to flow and form a large interface with another substance.

The surface tension (or inter-facial tension if the interface is not a surface) determines the tendency for surfaces to establish contact with one another. Therefore, surface tension is responsible for the shape of a droplet of liquid. If the surface tension is high, the molecules in the liquid are greatly attracted to one another and not so much to the surrounding air.

If the droplet of water is in contact with a solid such as a fabric, its shape will also be affected by the surface tension at the solid/liquid interface. If the surface tension in the liquid is lower, the droplet forms a more ellipsoidal shape.

The following are the surface tensions for some liquid substances:-

SUBSTANCE SURFACE TENSION

1. water 73 dynes/cm2. mercury 480 dynes/cm3. benzene 28 dynes/cm4. ethanol 22 dynes/cm

Because of its lower surface tension, ethanol will flow and form a larger area of contact (surface) with a solid than with water. Mercury, with its very high surface tension, does not flow but breaks into droplets if given the opportunity. Surface active agents interfere with the ability of the molecules of a substance to interact with one another and, thereby, lower the surface tension of the substance. Surfactants used in industrial applications usually cause a dramatic decrease in surface tension when used at low concentration.

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1.2 PROPERTIES:-

Chemically, surfactants are amphipathic molecules. That is, they have two distinctly different characteristics.

1. Polar 2. Non polar

In different parts of the same molecule.

Therefore, a surfactant molecule has both hydrophilic (water-loving) and hydrophobic (water-hating) characteristics. Symbolically, a surfactant molecule can be represented as having a polar “head” and a non polar "tail" as shown below.

non polar polar”head”(+)

“trailor”

1.2.1 CHARACTERSTICS OF TAIL GROUP(HYDROCARBON AND FLUROCARBON - APOLAR):-

a). Weak affinity for bulk solvent b). Strong affinity for air and oil

c). Adsorption at air (oil)-water interface.

1.2.2 CHARACTERSTICS OF HEAD GROUP:-

a). Strong affinity for bulk solvent (water) b). Weak affinity for air and oil c). Charged (polar) or neutral d). Adsorption at mineral-water interface.

Examples: sulphate, (SO3) amines.

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Example of polar and non-polar molecule:

The hydrophobic group in a surfactant for use in aqueous medium is usually a hydrocarbon chain but may be a fluorocarbon or siloxane chain of appropriate length. The hydrophilic group is polar and may be either ionic or nonionic.

Since surfactant molecules have both hydrophilic and hydrophobic parts, the most attractive place for them in water is at the surface where the forces of both attraction and repulsion to water can be satisfied. One other way that surfactants interact to satisfy natural forces of attraction and repulsion between molecules is by formation of micelles. Surfactant molecules aggregate in water forming micelles (see Figure). Micelles consist of hydrophobic interior regions, where hydrophobic tails interact with one another. These hydrophobic regions are

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surrounded by the hydrophilic regions where the heads of the surfactant molecules interact with water.

Schematic representation of surfactant molecules at surface and surfactant micelle

At very low concentration in water, surfactant molecules are unassociated. At higher concentration of surfactant in water, micelles form, The concentration at which micelles form is called the critical micelle concentration (CMC). The surface tension of water undergoes a precipitous decrease, and the detergency of the mixture increases dramatically at the CMC.

1.3 TYPES OF SURFACTANTS:-

Surfactants fall in the following

Classification according to the nature of the hydrophilic group:-

1. Cationic: hydrophilic head is positively charged;2. Non-ionic: hydrophilic head is polar but not fully charged; and3. Anionic:- hydrophilic head is negatively charged;4. Amphoteric: molecule has both potential positive and negative groups;

charge depends on pH of the medium.

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1.3.1 ANIONIC SURFACTANTS:-

In solution, the head is negatively charged. This is the most widely used type of surfactant for laundering, dishwashing liquids and shampoos because of its excellent cleaning properties and high sudsing potential. The surfactant is particularly good at keeping the dirt away from fabrics, and removing residues of fabric softener from fabricsAnionic surfactants are particularly effective at oily soil cleaning and oil/clay soil suspension. Still, they can react in the wash water with the positively charged water hardness ions (calcium and magnesium), which can lead to partial deactivation. The more calcium and magnesium molecules in the water, the more the anionic surfactant system suffers from deactivation. To prevent this, the anionic surfactants need help from other ingredients such as builders (Ca/Mg sequestrants) and more detergent should be dosed in hard water.

The most commonly used anionic surfactants are alkyl sulphates, alkyl ethoxylate sulphates and soaps.

A). SULPHATES:-

The sulfonate group is an effective solubilizing group when attached to an alkyl, aryl, or alkylaryl hydrophobe. Since the sulfonate group is a strong acid, the sulfonate surfactants are soluble and effective in acidic as well as in alkaline medium.

Example: Sodium Dodecyl Sulphate C12H25O(SO3)Na

B). SULPHONATES:-

Various fatty alcohols can be reacted with chlorosulfonic acid or sulfur trioxide to produce their sulfuric acid esters. The properties of these surfactants depend on the alcohol chain length as

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Example: Sodium dodecylbenzene sulphate

C). FATTY ACID AND SOAPS:-

Example: Sodium oleate. CH3(CH2)7=CH(CH2)7COONa

D). XANTHATHES:-

Example: Sodium ethyl xanthateCH3CH2OCS2Na

E). DITHIOPHOSPHATE:-

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1.3.2 CATIONIC SURFACTANTS:-

Cationic surfactants account for only 5-6% of the total surfactant production. However, they are extremely usefull for some specific uses, because of their peculiar properties. They are not good detergents nor foaming agents, and they cannot be mixed in formulations which contain anionic surfactants, with the exception of non quaternary nitrogenated compounds

They exhibit two very important features.:-

1. Their positive charge allows them to adsorb on negatively charged substrates, as most solid surfaces are at neutral pH. This capacity confer to them an antistatic bahavior and a softening action for fabric and hair rinsing. The positive charge enable them to operate as floatation collectors, hydrophobating agents, corrosion inhibitors as well as solid particle dispersant. They are used as emulsifiers in asphaltic emulsions and coatings in general, in inks, wood pulp dispersions, magnetic slurry etc.

2. Many cationic surfactants are bactericides. They are used to clean and aseptize surgery hardware, to formulate heavy duty desinfectants for domestic and hospital use, and to sterilize food bottle or containers, particularly in the dairy and beverage industries.

TWO COMMON TYPE OF CATIONIC SURFACTANTS:-

1. LONG CHAIN AMMINE:-

The long chain amine types are made from natural fats and oils or from synthetic amines. They are soluble in strongly acidic medium but become uncharged and insoluble in water at pH greater than 7. For example:-

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Benzalkonium or alkyl dimethyl benzyl-ammonium chloride

2. QUARTENARY AMMINE SALT:-

Quaternary amine type cationic surfactants are very important as fabric softeners. They absorb on the surface of fibers with their hydrophobic group oriented away from the fibers. This reduces the friction between fibers and imparts a soft, fluffy feel to the fabric.

1.3.3 NONIONIC SURFACTANTS:-

Nonionic surfactants do not produce ions in aqueous solution. As a consequence, they are compatible with other types and are excellent candidates to enter complex mixtures, as found many commercial products. They are much less sensitive to electrolytes, particularly divalent cations, than ionic surfactants, and can be used with high salinity or hard water. Nonionic surfactants are good detergents, wetting agents and emulsifiers. Some of them have good foaming properties. Some categories exhibit a very low toxicity level and are used in pharmaceuticals, cosmetics and food products.

Nonionic surfactants are compatible with other types of surfactants. Their low foaming tendency can be an advantage or disadvantage depending on requirements. They are good dispersing agents in many cases. They are more effective than sulfonate surfactants in removing s oil from hydrophobic fibers but are inferior to anionic surfactants for soil removal from cotton.

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Main Nonionic Surfactants

Surfactant Type % TotalEthoxylated Linear Alcohols 40Ethoxylated Alkyl Phenols 15Fatty Acid Esters 20Amine and Amide Derivatives 10Alkylpolyglucosides ---Ethleneoxide/Propyleneoxide Copolymers ---Polyalcolols and ethoxylated polyalcohols ---Thiols (mercaptans) and derivates ---

THREE TYPE OF CATIONIC SURFACTANTS:-

1. ETHOXYLATED ALCOHOLS AND ALKYLPHENOLS:-

2. FATTY ACID ESTER:-

The esterification of a fatty acid by a -OH group from polyethyleneoxide chain tip or polyalcohols generates an important family of nonionic surfactants.Their compatibility with biological tissues which make them suitable for pharmaceuticals, cosmetics and food stuffs.

3. NITROGENATED NONIONIC SURFACTANTS:-

It has been said previously that amines and amides can be ethoxylated. The first EO group must be added at acid pH, whereas the other ones (from the second group on) are added at alkaline pH.

Products such as ethoxylated amines consists in a fatty amine with one or two polyethylene glycol chains. Those with only 2-4 EO groups behave as cationic surfactants at acid pH. They are used as corrosion inhibitors and emulsifiers with a better water solubility than most cationics. Imidazoles, i.e. cyclic alkyl-diamines, are ethoxylated to produce fabric softeners for machine-washing, which also provide an anticorrosion protection for the hardware.

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1.3.4. AMPHOTERIC SURFACTANTS:-

Amphoteric or zwitterionic surfactants have two functional group, one anionic and one cationic. In most cases it is the pH which determines which of the groups would dominate, by favoring one or the other ionization: anionic at alkaline pH and cationic at acid pH. Near the socalled isoelectric point, these surfactants display both charges and are truly amphoteric, often with a minimum of interfacial activity and a concomitant maximum of water solubility. Amphoteric surfactants, particularly the aminoacid ones are quite biocompatible, and are used in pharmaceuticals and cosmetics.

1. IMIDO PROPIONIC ACIDS:-

Their general formula is HOOC-CH2-CH2-RN+H-CH2-CH2-COO-. Their isoelectric point is around pH = 2-3. They are thus more water soluble than the previous ones. They are used as textile softeners. Dicarboxylic compounds of alkyl imidazole, in which the alkyl group is located on the carbon placed between the nitrogen atoms, are used in cosmetics and de luxe soap bars.

2. QUATERNIZED COMPOUNDS:-

Quaternized compound have similar structures. The most important are betaines and sulfobetaines or taurines, which have a single methylene group between the acid and the quaternary ammomium.

R-N+(CH3)2-CH-COO- alkyl betaine

R-N+(CH3)2-CH2-SO3- alkyl sulfobetaine

These surfactants are amphoteric at neutral and alcaline pH, and cationic at acid pH (at which the carboxylic acid is not ionized). Since the nitrogen atom is quaternized, these surfactants always display a positive charge. They tolerate a high salinity, particularly divalent cations, e.g. calcium and magnesium. They are

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the most used class of amphoteric surfactants. They are found in softeners for textiles, hair rinse formulas, and corrosion inhibition additives. They are good foam boosters because of their cationic characteristics.

1.4 APPLICATION OF SURFACTANTS:-

1. It is act as anti-foaming agent

2. It useful in making inks

3. Surfactants are added to gasoline as detergents, dispersants, corrosion inhibitors and carburetor anti-icing additives.

4. Detergents, dispersants and corrosion inhibitors, similar to those used in gasoline, are being used in some diesel fuels. Deposit problems which occur in the carburetor in gasoline engines.

5. It is used in paints, detemper.

1.5 HARMFUL EFFECT BY SURFACTANTS:-

Some surfactants are known to be toxic to animals, ecosystems and humans, and can increase the diffusion of other environmental contaminant. Despite this, they are routinely deposited in numerous ways on land and into water systems, whether as part of an intended process or as industrial and household waste. Some surfactants have proposed or voluntary restrictions on their use. For example, PFOS is a persistent organic pollutant as judged by the Stockholm Convention.

1.6REFERENCES:-

BOOK

1. INDUSTRIAL SURFACTANTS- 2ND EDDITION- Ernest W. Flick2. N.C.E.R.T CHEMISTRY

WEBSITE:-

1. http://docs.google.com/viewer?a=v&q=cache:GRuHsFbjeDMJ:www.p2pays.org/ref/03/02960.pdf+PDF+ON+SURFACTANTS&hl=en&gl=us&pid=bl&srcid=ADGEEShZ92xRqa2WCuoKYRBNuptdnyGP3jRhFVP8B87PBHCmmk_Rbti1Np8RCH-

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biFcwfw7g8hCVum3CmyUTDaOquhyI0Z8BQ4Hnz7C5eqgICWjNOOmO9H0hMCFsUw4h8CrEOmJLConV&sig=AHIEtbQq55O8F52ihJclEyhJG91bQvmLaA

2. http://en.wikipedia.org/wiki/Surfactant