REMOVAL OF TRACE LEVELS OF AROMATIC-AMINES FROM AQUEOUS-SOLUTION BY FOAM FLOTATION

Aromatic amines, including 4-(t-butyl)pyridine, 4-(n-butyl)aniline, benzylamine, 4-aminobiphenyl, 1- and 2-aminonaphthalene, and 2,6-xylidine, were effectively removed from water by foam flotation with the anionic surfactant sodium dodecylsufate (SDS). With initial amine concentrations of 10 mg/L or less, residual amine concentrations of less than 0.1 mg/L were generally obtained after 10–30 min of flotation. The SDS concentration and flotation time are directly related to the amount of amine removed. Amine removal is most efficient at pH values low enough so that the amine is protonated (usually about 3), and at lg178ow ionic strength. Alcohols up to 10% by volume do not appreciably affect amine removal. The mechanism of removal is dominated by ion-ion attraction between the surfactant and the protonated amine; there is also apparently some contribution from ion-dipole attraction. Benzidine is not removed effectively; evidently it is insufficiently hydrophobic. © 1990, Taylor & Francis Group, LLC. All rights reserved.