Einfluß der chemischen Struktur auf ökotoxikologische Eigenschaften von Alkanol-Ethoxylaten / Chemical structure of alkanol ethoxylates and ecotoxicological properties
| Autor: | K. Taeger, U. Kaluza |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | Tenside Surfactants Detergents. 33:46-51 |
| ISSN: | 2195-8564 0932-3414 |
| Popis: | The biodegradability and ecotoxicity of alcohol ethoxylates depend on the length of the alkyl chain, the extent of branching, and the degree of ethoxylation. These factors also determine whether they must be labelled as Dangerous for the environment. The length of the alkyl chain has little effect on the degradability in the C 10 to C 15 range, provided that there is no difference in the structure and that the degree of ethoxylation remains constant, but it has a very significant effect on ecotoxicity. The 7 mol C 15 ethoxylate has an EC 50 of less than 0.1 mg/l, but the corresponding value for the iso-C 10 ethoxylate is about 50 mg/l. In order to achieve the magic limit of 1 mg/l, ethoxylated products with 7-8 mol EO must have a chain length in the C 13 range, but both, ecotoxicity and biodegradability, decrease with increasing branching in this range. This has consequences for the environment and labelling. Three different tridecanol ethoxylates were tested in a series of experiments designed to test this inverse correlation between biodegradability and ecotoxicity. They were all ethoxylated with 7-8 mol EO, and they had the same EC 50 of about 5 mg/l. A technical-grade product based on propene tetramer and a single-branched product, 2-propyldecanol/2-pentyloctanol, prepared in the laboratory, were found to be much less biodegradable than a technical-grade product based on butene trimer. These findings were supported by additional tests on the product based on butene trimer in comparison with a readily biodegradable product made from renewable raw materials. They were subjected to other OECD Screening Tests, a Biodegradability-Ecotoxicity Sequence Test (BEST) consisting of a simulation test combined with a test for chronic toxicity to Daphnia, and a catabolite test for determining stable degradation products. Both products meet the criteria for ready biodegradability. They were completely eliminated in the continuous activated-sludge simulation test. The treated waste water discharged from the laboratory-scale treatment plant had no chronic toxic effect on Daphnia, and stable catabolites did not accumulate. These product do not impose any potential hazards on the environment if they are used properly. |
| Databáze: | OpenAIRE |
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