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%).Technical cashew nut-shell liquid (CNSL), obtained by the industrial processing of phenolic lipids in the natural material Anacardium occidentale, which contains principally anacardic acid 1, cardol 2, and 2-methylcardol 3. Decarboxylation gives cardanol 4, together with unchanged cardol, as shown in Scheme 1. The polyethoxylates 5 and 6, depicted in Scheme 2, were obtained by the reaction of cardanol and cardol with ethylene oxide (1). t-Nonylphenol polyethoxylate 7 is shown for comparison. In each case, they contain a profile of oligomers in which m ranges from 1 to about 48. The ethoxylates were deemed ideal candidates for further surfactant and biodegradation studies, specifically, by first determining the optimal number of ethoxylate (EO) groups required for surfactancy, as judged by their relative reduction of the surface tension of water. With this information, biodegradation studies were carried out on the sample in each series exhibiting the highest surfactancy.Studies on the environmental occurrence of alkylphenols and alkylphenol ethoxylates (2) and their persistence in aquatic environments have both been reviewed extensively (3). Commercial alkylphenol polyethoxylates have received criticism on environmental and toxicological grounds (4), and although subsequent studies have suggested their accumulation is not significant (5), there also have been indications that they could be gradually phased out (6). Recent work (7) has indicated the continued existence of marine pollution with alkylphenol polyethoxylates. Studies on the response of activated sludge to variations in the composition of feed effluent (8) have indicated that alkyl ethoxylateadapted biomass was more capable of adaptation to alkylphenol ethoxylate than the reverse. Overall, there are conflicting views on the fate and effect of the present class of alkylphenol polyethoxylates in the environment.Since approximately 90% of the alkylphenol ethoxylates in the European Union are based on the petrochemical intermediate t-nonylphenol, it is of interest to examine the use of natural alkylphenols, based on the supposition that a biosynthesized compound might prove to be more biodegradable and environmentally acceptab...

Polyethoxylates from cardanol and from cardol, the main component phenolic lipids in technical cashew nutshell liquid derived from the replenishable source Anacardium occidentale, were obtained by reaction with ethylene oxide under base-catalyzed conditions. Oligomeric mixtures resulted. In the cardanol series, the first six members of the mixture were independently synthesized for characterization purposes by a variety of reactions. The members in the oligomeric mixture were separated by HPLC, and the composition was determined by 1 H NMR spectroscopy and by chromatography. These studies were preparatory to surfactant and biodegradation studies involving comparison with commercially available polyethoxylates derived from petrochemical nonylphenol.

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The oligomers (m = 1,2,3,4 and 5) in the profile of compounds obtained in the ethoxylation of saturated cardanol with ethylene oxide have been synthesised. The first member which occurs only in traces in the reaction has now been synthesised by an improved method. This monoethoxylate of 3-pentadecylphenol and a diethoxylate of 5-pentadecylresorcinol (2-hydroxyethyl derivatives) have been synthesised by the base-catalysed reaction with ethylene carbonate. Cardanol and cardol separated from technical cashew nut-shell liquid (CNSL) have been similarly reacted as have saturated cardanol and saturated cardol obtained by reduction of the side-chain. Reaction of the anhydrous potassium salt of 3-pentadecylphenol in dichloromethane with ethylene sulfate has afforded a derivatives having a sulfate group in place of the terminal hydroxyl group and avoiding the use of sulfuric acid. Similarly CNSL and saturated CNSL reacted with ethylene sulfate gave sulfo derivatives which possess excellent surfactancy. By contrast, with sulfuric acid, 3-pentadecyl phenol monoethoxylate gave a trisulfo product comprising a terminal side-chain sulfate and a ring disulfonic acid. 3-Pentadecylphenol reacted with sulfuric acid in carbon tetrachloride to give 4-hydroxy-6-pentadecylphenol-1,3-disulfonic acid.

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