Adsorption of BDE-209 to Polyethylene Microplastics: Effect of Microplastics Property and Metal Ions

In this work, the effect of polyethylene microplastics (MPs) on the adsorption of decabromodiphenyl ether (BDE-209) in a sandy loamy soil and aqueous solution was investigated by performing batch tests. Results show that the overall adsorption capacity of soil/MPs mixture decreased slightly after MPs spiking because of the dilution effect, namely MPs were weaker receptor for BDE-209 than the soil particles. The adsorption capacity increased with reducing the MPs size. The equilibrium adsorption amount of aged MPs (4.15 mg/kg) declined apparently compared with that of the original MPs (7.63 mg/kg). According to the fitting parameters of kinetic and isothermal adsorption study, the adsorption of BDE-209 by MPs was a heterogeneous and multi-layer uneven adsorption process. The existence of Cu 2+ ions or humic acid exerted a negative impact on the adsorption of BDE-209. In summary, the findings of this work underline the potential significance of MPs as contaminant carriers in co-contaminated soils.