Ozone-cleavable gemini surfactants. Their surface-active properties, ozonolysis, and biodegradability

A series of bis(sulfonate) or bis(carboxylate) types of double-chain surfactants (gemini surfactants) containing carbon-carbon double bond(s) in their lipophilic chains and/or the connecting part were prepared with the intention of developing high-performance surfactants having a decomposition character toward ozone. Some profiles with respect to the structural effect of the double bond(s) on the surface-active properties of these gemini types of surfactants were revealed as follows: (1) the displacement of a C-C bond by a C=C bond in the connecting part made a positive contribution both to micellar formation and to the effectiveness and efficiency of adsorption on the surface; (2) in contrast to this, a C=C bond in the lipophilic chains of gemini surfactants made a negative contribution to these properties. Ozonolysis of these gemini surfactants was easily accomplished by passing ozone through their micellar aqueous solutions followed by successive reduction of the resulting mixtures with NaBH4. A remarkable change in foaming properties was observed before and after the ozonolysis; that is, foam stability of all examined ozonolytic products was extremely low. Finally, biodegradability of some gemini surfactants and their ozonolytic product by activated sludge was estimated. Their degradabilities were much higher than that of sodium dodecyl-benzenesulfonate and were comparable to that of sodium 1-dodecanesulfonate under the same conditions.