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Alkyl Benzene Sulfonates
Gisha G.PMSc
BiotechnologyMahatma Gandhi
University, Kottayam
Environmental Impact and Remedies
Introduction • Domestic waste water is one of the important
pollution sources affecting the water quality
adversely in many countries.
• Waste waters containing detergents are the
basic constituents of organic pollutants and they
cause great environmental damages by
introducing into the soil, lakes and rivers.
• Detergents are the mixtures of surfactants and
their isomers and preferred to soap because of
their many superior properties. As a result of
economic development and population growth,
environmental problems caused by detergents
are increasing day by day.
Chemistry …..• Alkyl benzene sulfonates are the major
components of anionic detergents.
• alkyl benzene is a family of organic compounds with the formula C6H5CnH2n+1.
• Typically, n lies between 10 and 16, although generally supplied as a tighter cut, such as C12-C15, C12-C13 and C10-C13, for detergent use .
• This molecule has a polar( sulfonate ) and non polar(alkyl) end.
• Alkyl benzene sulfonates classified into 2
groups:
branched and linear chain
• Type of substance : organic acid sodium salt
• Physical state(20ºC): solid
• Molecular weight: 342.4
• Vapour pressure(25ºC) : 3x10-13 Pa
• Boiling point : 637ºc
• Melting point: 198.5ºc
• Water solubility: 250g/l
• Density : 1.06kg/l
• pH (5%LAS soltn): 7-9
• Trade name: Marlon A
ABS & LAS
• Linear and branched alkylbenzene sulfonates (LAS and ABS) are the most important anionic surfactants widely used in the formulation of house hold detergent and industrial cleaning products.
• The concentration of this anionic material in the detergent industries wastewater is too high and discharges generate critical problems and unrestorable damages such as poisoning of waterlife , pollution of ground water, and formation of foams in rivers.
• Although ABS was an effective detergent it has slow rate of biodegradation in the environment.
• It become apparent that ABS based detergent were contributing to pollution of lakes and streams by forming relatively stable foams .
• Resistance of branched ABS to biochemical degradation in aquatic environments also posed to threat to municipal drinking water supplies , which were using surface water as a source for drinking water production.
• LAS was first commercialized in 1965s as a replacement for the poorly biodegradable Alkylbenzene Sulfonate (ABS) which caused persistent foam in sewage treatment plants, streams and rivers. LAS was the first surfactant introduced to solve an environmental problem.
• LAS has been shown to affect the flora and fauna of aquatic ecosystems. It has been observed that this compound denatures proteins in the cell membrane, altering the permeability of the membrane to nutrients and other chemical substances , but it can readily destroyed by microbial action.
Manufacturing route
• The first ABS was obtained by the Friedle-Crafts alkylation of benzene with polyproplenetetramer. The tetramer is a mixture of C12 olefins. As a result the corresponding ABS is highly branched .
• The detergent produced is then sulfonatedwith oleum or sulfer trioxide followed by neutrilization with NaOH or soda ash.
• LAS is comprised of linear alkyl carbon chains (C10-C13), SO3- and Na+. LAS is made from kerosene and benzene through Linear AlkylBenzene (LAB) with further sulphonation
Human health assessment
• The toxicological data show that LAS was
not genotoxic in vitro or in vivo.
• The critical adverse effect identified after
repeated long term high dosing of LAS to
animals was a change in renal
biochemical parameters.
Environmental risk assessment
Aquatic
• Toxicity tests have been conducted with LAS on a wide
range of fresh and saltwater fish, invertebrates and
algae.
• Acute toxicity of LAS to most fish and invertebrates is in
the 0.5 mg/L to 20 mg/L range.
• The aquatic toxicity of LAS to algae has a greater spread
of responses, with 90% of the species having an EC50
between 0.1 mg/L and 100 mg/l .
• The alkyl chain length affects the acute toxicity of LAS.
The EC50 for the different chain lengths of LAS to
Daplznia magna were found to be 0.68, 2.6, 5.9, 21.2
and 27.6 mg/L for the C14, C13,C12, C11,and C10 LAS
Sediment
• The results from the U.S.G.S. study indicate that LAS concentrations in the sediment are more than five times lower than the lowest NOEC reported for the most sensitive species tested.
• The data indicate that LAS is not impacting sediment organisms in spite of the large wastewater input and the lack of secondary treatment by several large metropolitan cities along the river.
Biodegradation
• Destruction of chemical by the metabolic
activity of micro organisms
• LAS are biodegadable surfactants.
• Mechanism of breakdown involves the
degradation of the straight alkyl chain, the
sulphonate group and finally benzene ring.
• Alkyl chain breakdown starts with the
oxidation of the terminal methyl group( -
oxidation) through alcohol, aldehyde to
carboxilic acid.
• The reaction is catalyzed by alkane
monooxygenase and two dehydrogenase.
• The carboxylic acid undergoes -oxidation
and two carbon fragment enters TCA cycle
as acetyl CoA.
• In case of ABS , the side chain methyl
group cannot undergo -oxidation by
micro organisms
• Second stage of breakdown , is the
degradation of sulphonate group.
Desulphonation occurs through either of
the 3 proposed way:
• Breakdown product of LAS is sulphite ,
and is oxidised to sulphate in the
environment.
• Loss of alkyl and sulphonate group from
LAS leaves either phenylacetic or benzoic
acid
• Microbial oxidation of phenylacetic acid is
fumaric and acetoacetic acids and
benzene is converted to catechol
• The complete biodegradation of
surfactants requires a consortium of
bacteria due to the limited metabolic capacities of individual microorganisms.
• Consortium of bacteria comprises of
Pseudomonas aeroginosa, Bacillus
subtilis, Bacillus aglomerans, Bacillus
cereus, Bacillus alvae
• Cultures isolated from the fresh water
layer of river had greater ability to degrade
LAS than those from the underlying saline
water layer.
• Degradation rates was faster for the
longest alkyl chain LAS and slower for
isomer having the sulphophenyl group
situated in the middle of the alkyl chain.
Literature cited• Biodegradation of Surfactants in
the Environment. Matthew J
Scott , Malcom N Jones
• FATE OF THE BENZENE RING OF
LINEAR ALKYLBENZENE
SULFONATE IN NATURAL
WATERS . R. J. Larson* and A. G.
Payne ., APPLIED AND
ENVIRONMENTAL
MICROBIOLOGY.
• BIODEGRADATION OF LINEAR
ALKYL BENZENE SULFONATE
BY BACTERIAL CONSORTIUM.
Praswasti PDK Wulan, Misri
Gozan, Anondho W, Dianursanti,
Mahmud S
• MICROBIAL METABOLISM OF
. A. J. Willetts and R. B. Cain., Biochem. J. (1972)
• LINEAR ALKYLBENZENE
SULFONATE TOLERANCE IN
BACTERIA ISOLATED FROM
SEDIMENT OF TROPICAL WATER
BODIES POLLUTED WITH
DETERGENTS. Kehinde I.T.
Eniola & Albert B. Olayemi
• LAS -Linear Alkylbenzene
Sulphonate , Revised
ENVIRONMENTAL Aspect of the
HERA Report February 2013
• Linear Alkylbenzene Sulphonate -
The Soap and Detergent
Association
Thank you