Extraction of aromatic acids and phenols by polyurethane foam

The extraction of several aromatic acids and phenols including salicylic acid, 8-hydroxyquinoline, 1-amino-2-naphthol-4-sulphonic acid and cinnamic acid in the presence of various protonated alkylamines, ammonia and alkali metal cations from aqueous solution by polyurethane foam has been investigated. These compounds are extracted only in the neutral form by a solvent extraction mechanism. The mechanism has been confirmed by the salting-out effect and pH studies. With the exception of 8-hydroxyquinoline, the compounds are more extractable by polyether foam than by polyester foam, suggesting that hydrogen bonding is stronger with the polyether foam.