• • Fe3O4@MIL-100(Fe) achieved >98% removal of both PLA and PS under acidic conditions (pH < 4) and high ionic strength (≥10 mmol·L−1 NaCl), demonstrating robust performance for treating realistic wastewater matrices.
• • The composite exhibited a high specific surface area of 848.6 m2·g−1, providing abundant active sites for adsorption, which is critical for achieving high capacity and fast kinetics in continuous-flow systems.
• • Adsorption kinetics followed pseudo-second-order for PLA (R2 > 0.99) and both pseudo-first-order and pseudo-second-order for PS, indicating chemisorption as the rate-limiting step, essential for designing fixed-bed adsorbers.
• • The material retained stable removal efficiency over multiple adsorption-desorption cycles, confirming its reusability and economic viability for large-scale water treatment applications.