Abstract
The tests for acute toxicity to fish were carried out on nine commercial surfactants of various chemical structures including secondary alcohol derivatives.
The tests were extended to study the toxicity of biodegradation intermediates of some surfactants in river water. It was found that the TLm (48 h) values of alcohol ethoxylates and nonylphenol ethoxylates after 4 days biodegradation in river water were 91 mg/l and 3.7 mg/l, respectively, based on the initial concentration.
The tests were also extended to see the relationship between changes in surface tension and changes in toxicity. In the case of alcohol ethoxylates, surface tension of 48 dyn/cm after 4 days biodegradation was found to be high enough for fish to be alive, while in the case of nonylphenol ethoxylates, 51 dyn/cm was found to be too low for fish to be alive.
