Cloud point extraction of bisphenol a from water utilizing cationic surfactant aliquat 336

In this study, cloud-point extraction (CPE) using a cationic surfactant, tricaprylmethylammonium chloride (Aliquat 336), was carried out to separate and concentrate bisphenol-A (BPA) from aqueous media. Cloud-point phase separation of Aliquat 336 at room temperature (25 °C) was induced by the addition of Na2SO4. The parameters influencing the extraction efficiency, such as concentrations of Aliquat 336 and Na₂SO₄, cosolvent (methanol), pH value and extraction time were evaluated. The results showed that the extraction efficiency was practically constant in the studied range of Aliquat 336, cosolvent (methanol), pH, and dissolved organic matters. Under the operational CPE conditions, distribution constant, KD, of the distribution of BPA between the surfactant-rich and aqueous phases of the CPE system was estimated to be approximately 104. Coupled to liquid chromatography with UV detection, the CPE method offered a detection limit of 0.34 μg l_-1 in distilled water and recovery of BPA ranged from 90% to 108.6% with a sample volume of 50 ml in the three matrices studied. The high extraction efficiency might be due to the combination of ion pair, hydrophobic effects, and cation-π interaction, based on the micellars' size distribution and Zeta potential analysis. Copyright © 2009. Changchun Institute of Applied Chemistry, Chinese Academy of Sciences.