Surfactant-coated aluminum hydroxide for the rapid removal and biodegradation of hydrophobic organic pollutants in water

The removal of hydrophobic organic pollutants in water to surfactant-coated aluminum hydroxide [surfactant-Al(OH)3] was investigated. Anionic surfactants such as sodium dodecyl sulfate (SDS), sodium bis(2-ethylhexyl)sulfosuccinate (AOT), and sodium oleate were sorbed on positively charged aluminum hydroxide at pH 7 and formed hydrophobic aggregates that can incorporate hydrophobic organic pollutants in water. Because of the hydrophobic interaction and decrease in the positive charge, surfactant-Al(OH)3 was coagulated into precipitates that can readily be separated from water. Hydrophobic organic pollutants such as alkylphenols, polycyclic aromatic hydrocarbons, estrogens, chlorinated antifungals, and pesticides were well collected to the precipitates and thus efficiently removed from water. The collection of hydrophobic organic pollutants was correlated to their aqueous-octanol distribution coefficient. The decomposition of hydrophobic organic pollutants was examined using a bacterial agent (Bacillus subtilis). Hydrophobic organic compounds collected to AOT-Al(OH)3 or sodium oleate-Al(OH)3 were insufficiently decomposed. On the other hand, nonylphenol, octylphenol, and pendimethalin collected to SDS-Al(OH)3 were decomposed within 1 week. The decomposition was accelerated by the collection to SDS-Al(OH)3.

Research highlights
► We designed a method for the removal of hydrophobic organic pollutants in wastewater.
► Surfactant-coated aluminum hydroxide provided hydrophobic media in water.
► Hydrophobic organic pollutants were well collected to the hydrophobic media.
► The applicability to the practical wastewater treatment was investigated.
► The collected organic pollutants were decomposed with a bacterial agent.