Adsorption of tetrabromobisphenol A on soils: Contribution of soil components and influence of soil properties

The adsorption of tetrabromobisphenol A (TBBPA) on several typical Chinese soils and soil mineral and organic components were comprehensively investigated in the present study. The adsorption isotherms were well described by the Freundlich equation and the corresponding adsorption capacity constant Kf ranged from 2.46 to 357.30 L/kg and 16.52 to 136,731.98 L/kg for the original soils and the soil components, respectively. Correlation analysis between the adsorption capacity and soil properties indicates that soil pH and soil organic carbon (SOC) content were the predominant factors determining TBBPA adsorption on the soils. At constant pH of 7.0, the soils with higher SOC content exhibited stronger adsorption affinity for TBBPA, suggesting the significant importance of SOC in the adsorption. The adsorption affinity of TBBPA became weaken for a given soil with increasing pH due to the enhanced electrostatic repulsion between the anionic TBBPA species and soil surface. Humins and black carbon of SOC played a predominant role in while soil minerals contributed slightly to the adsorption of TBBPA on the soils. The results of this study will provide a better understanding of the behaviors of TBBPA in soils.