Biodegradability and Toxicity of Anionic Surfactants

Alkyl sulphates of the general formula CH_{2n + 1}-O-SO₃Na and alkyl sulphonates of the general formula C_nH_{2n + 1}-SO₃Na, where n = 8, 10, 12, 14 in each series have been tested for biodegradability with the modified OECD screening test No. 301 E, and for toxicity with Daphnia magna and with Photobacterium phosphoreum (the Microtox^TM test). The results show that both alkyl sulphates and alkyl sulphonates are biodegraded with the alkyl sulphates degrading more rapidly under the test conditions. The alkyl sulphates also have higher toxicity to both test species and for both alkyl sulphates and sulphonates the toxicity increases linearly with increasing molecular weight of the surfactant.