Interaction of tetrabromobisphenol A (TBBPA) with microplastics-sediment (MPs-S) complexes: A comparison between binary and simple systems

The presence of microplastics (MPs) and the associated organic pollutants in the aquatic environment has attracted growing concern in recent years. MPs could compete with chemicals for adsorption sites on the surface of sediment, affecting the sorption processes of pollutants on sediment. However, few studies focused on the binary system of microplastics-sediment (MPs-S), which appear much common in aquatic environment. Herein, we investigated the interactions between a continuously used flame retardant tetrabromobisphenol A (TBBPA) and four MPs-S complexes (PVC-S, PE-S, PP-S and PS-S). The equilibrium adsorption capacities were 17.1, 15.6, 15.4, and 14.0 mg/kg for PVC-S, PS-S, PE-S, and PP-S, respectively. Kinetics suggest that adsorption behavior of TBBPA was fitted by pseudo-second-order model. Co-adsorption of TBBPA in binary systems were much lower than the sum of each simple system, which may be due to the mutually occupied adsorption sites. Higher ionic strength and lower dissolved organic matter strengthened the sorption of TBBPA onto MPs-S complexes. The enhanced sorption capacities for TBBPA were observed with elevated proportion and small particle size of MPs in the MPs-S complexes. This study contributes to the knowledge on the impact of MPs in partitioning of organic pollutants in-between solid and aqueous phases in the aquatic environment.