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Environmental fate & pathways

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Additional information

All alkyl ketene dimers are classified as readily biodegradable based on the ready biodegradability test result of 2-Oxetanone, 3-C12-16-alkyl-4-C13-17-alkylidene and the biodegradation mechanism of ketones

Experimental data on the biodegradation in water and sediment or soil of alkyl ketene dimer are not available. Therefore, for the degradation rate the default value according to the TGD is estimated, assuming that no degradation takes place in the bound phase. As no tests under anaerobic conditions are available, it is assumed that the substance is not degraded in the anoxic sediment layer. The partitioning of AKD in soil, sediment and sludge was calculated using the maximum Koc value of 1 * 106L/kg. The suggested half-life for alkyl ketene dimmer in the aerobic sediment is 30000 days and 300000 days for the bulk sediment. The suggested half-life for alkyl keten dimmer in bulk soil is 30000 days. Chemical hydrolysis of AKD is not influenced by adsorption onto solids nor by the absence of oxygen and therefore the half life in the aerobic sediment layer, in the anaerobic bulk sediment and in the bulk soil should be based on the hydrolysis rate in the aqueous phase. The hydrolysis half live in the aqueous phase at pH 8 and 25 °C ranges between 35 to 210 hours.