Effect of Microplastics on the Adsorption and Desorption Properties of Cadmium in Soil

This study analyzed the role of micro polyethylene (mPE) and micro polypropylene (mPP) on cadmium (Cd) adsorption and desorption in soil. Cd adsorption in soils reached equilibrium within 240 min with or without mPP/mPE. The largest Cd adsorption amount was 923.88 mg kg−1 in the control treatment (no MPs). The Cd adsorption amount in the mPP treatment was 872.21 mg kg−1, greater than that in the mPE treatment (780.21 mg kg−1). MPs reduced the soil adsorption of Cd to some extent. Soils supplemented with mPE were more inhibitory to Cd adsorption than mPP. The pseudo-second-order model equation proved to be the most optimal equation for describing Cd adsorption dynamics in the presence of different MPs, while the Freundlich equation was best for describing isothermal adsorption of Cd in the presence of MPs. MPs facilitate the desorption of metals from the soil.