Sorption behavior of bisphenol A on marine sediments

Abstract

Bisphenol A (BPA) is a known endocrine disrupting chemical (EDC) that has been widely used for the production of polycarbonate plastics and epoxy resins. In this experimental study, the sorption behavior of BPA on the marine sediments sampled from 6 different sites in the Mai Po Nature Reserve in Hong Kong was investigated. BPA sorption on the sediments can be well described by a linear sorption isotherm, suggesting a partition of BPA between the aqueous solution and the organic matter of the sediments. The BPA partition coefficient, K _d , for the raw sediment samples varied from 4.43 to 8.54 L/kg (R² : 0.91–0.96) in nearly proportion to the organic content of the sediments. After the treatment of H₂O₂ oxidation for organic removal, the sediments had the K _d value reduced by more than 50%. However, the organic residue or black carbon of the sediments after the H₂O₂ treatment had a much greater sorption capacity than the natural organic matter on the sediment which was oxidized by H₂O₂. The organic normalized partition coefficients (K _oc ) averaged around 1355 L/kg for the H₂O₂-treated sediment, which was more than three times greater than the K _oc value of 447 L/kg for the raw organic matter of the sediments. In addition to the organic content of the sediment, BPA sorption also was affected by a number of environmental factors. A pH drop, a temperature decrease and a reduction in salinity would increase the sorption of BPA on the sediment. The research findings are of significance to the description and assessment of the fate and transport of BPA and other similar EDCs in marine water-sediment systems.

Keywords:

• Bisphenol A
• sorption
• partition
• sediment
• seawater

Acknowledgments

This research was supported by grants HKU7120/03E from the Research Grants Council (RGC) and AoE/P-04/2004 from the University Grants Committee (UGC) of the Hong Kong SAR Government, China. The technical assistance of Mr. Keith C. H. Wong is highly appreciated.

This paper was presented at the SETAC Asia/Pacific 2006 conference held at Peking University, China on September 18–20, 2006.