Surfactant properties and biodegradation of polyethoxylates from phenolic lipids

The surface tension of aqueous solutions of cardanol and cardol polyethoxylates derived from technical cashew nut‐shell liquid were examined to determine their relative surfactancy. The compositions with the greatest surface tension reduction, or optimal surfactancy, were selected for biodegradation testing, in terms of total organic carbon, using a soil inoculum. The experimental surfactants in this study were compared with commercial t‐nonyl polyethoxylate and glucose as reference materials. Over a period of 28 d, cardanol polyethoxylate and its saturated analog were degraded to 17 and 25%, respectively, and cardol polyethoxylate and its saturated analog were degraded approximately half that extent (37 and 46%). t‐Nonylphenyl polyethoxylate remained substantially undegraded (77%), whereas glucose was almost completely degraded (5%).