Efficient and highly selective deep removal of hydrophobic organic compounds from leachate by polyamide microplastics

High levels of hydrophobic organic compounds (HOCs) have been detected in the landfill leachates. However, due to the complex leachate composition with high organic content, removing HOCs has proven to be challenging. Herein, we focused on the efficiency and selectivity of polyamide microplastics (PA MPs) in adsorbing HOCs from real landfill leachate. Using bisphenol A (BPA) as a model HOC, PA MPs highly selectively removed 100 % of trace concentrations (1–500 μg·L^-1) of BPA from leachate containing 827 mg·L^-1 of dissolved organic carbon (the concentration ratio of DOC/pollutant was up to 8.27 × 10⁵). Density functional theory calculations confirmed that the selectivity of PA MPs in leachate was primarily related to hydrogen bonding. Various environmental factors (solution pH, anions, natural organic matters, hydrophilic pollutants, dissolved organic carbon, and the high chroma of leachates) had little effects on the adsorption of BPA. Furthermore, PA MPs were completely removed by magnetic zero-valent iron loaded with porous carbon through simple shaking. This study demonstrates PA MP's effectiveness in selectively removing trace HOCs from leachate and showed significant industrial potential for wastewater treatment.