Abstract

Three components of sediments with regard to the sorption-desorption characteristics of tetrabromobisphenol A (TBBPA) in sediment water systems were investigated. Results show that the Freundlich and Langmuir model can describe the sorption behavior of TBBPA well. The calculated Γmax (maximum unit sorption quantity) values were 1.47, 2.13, and 3.65 mg/kg for mineral group (MG), clay group (CG), and humin group (HG) sediments, respectively. HG exhibited a stronger nonlinear behavior than did CG and MG. The order of sorption capability was as follows: HG > CG > MG. Desorption capability order was the opposite. Simultaneously, it was found that precipitation was the main sorption type for TBBPA on sediment. The contribution of precipitation sorption ranged from 45 percent to 70 percent within a TBBPA concentration ranging from 0.1 to 10.0 mg/L in the supernatant. This may be attributable to anomalous changes in the compounds' ionic activity in combination with metal cations. Sorption-desorption experiments on clay sediment were also conducted at pH levels ranging from 3 to 14 and temperatures ranging from 4°C to 30°C. In this regard, the sorption of TBBPA decreased as pH and temperature increased gradually. Furthermore, sorption and desorption reached a dynamic equilibrium at pH 11.5 and at a temperature of 30°C, respectively. The release of TBBPA from sediment would be higher in summer than in the three other seasons, which may pose a potential ecological risk for aquatic life in lakes.

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