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Alkyl benzene sulfonates

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  • 1. Alkyl Benzene Sulfonates Gisha G.P MSc Biotechnology Mahatma Gandhi Environmental Impact University, Kottayamand Remedies

2. 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. 3. 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. 4. 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 C12C15, C12-C13 and C10-C13, for detergent use . This molecule has a polar( sulfonate ) and non polar(alkyl) end. 5. Alkyl benzene sulfonates classified into 2 groups: branched and linear chain 6. Type of substance : organic acid sodium salt Physical state(20C): solid Molecular weight: 342.4 Vapour pressure(25C) : 3x10-13 Pa Boiling point : 637c Melting point: 198.5c Water solubility: 250g/l Density : 1.06kg/l pH (5%LAS soltn): 7-9 Trade name: Marlon A 7. 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. 8. 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 9. 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 10. Manufacturing route The first ABS was obtained by the FriedleCrafts alkylation of benzene with polyproplene tetramer. The tetramer is a mixture of C12 olefins. As a result the corresponding ABS is highly branched . The detergent produced is then sulfonated with 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 11. 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. 12. 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 13. 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. 14. Biodegradation Destruction of chemical by the metabolic activity of micro organisms LAS are biodegadable surfactants. 15. 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. 16. 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: 17. 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 18. 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 19. 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. 20. 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. 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 21. Thank you

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