Magnetic γ-alumina derived from aluminum dross as a sustainable material for polyvinyl chloride microplastic remediation

This study explores the upcycling of aluminum dross into magnetic g-alumina (MGA) material via co-precipitation, followed by calcination at 600 °C and 900 °C to yield gamma alulmina precursors with Al 2 O 3 purities of 79.2 wt% and 91.3 wt%, respectively. These two precursors were subsequently magnetically modified via co-precipitation to produce two magnetic material variants, MGA-600 and MGA-900. MGA-600 exhibits a BET surface area of 243.1 m 2 /g and saturation magnetization of 10 emu/g, whereas MGA-900 demonstrates a surface area and saturation magnetization of 131.43 m 2 /g and 40 emu/g, respectively. The materials were applied to UV-aged polyvinyl chloride (PVC) microplastics in aqueous media, achieving removal efficiencies of 87% for MGA-600 and 76% for MGA-900. Removal efficiency remained robust across pH (5 to 9), temperature (30°C, 40°C, 50°C), and ionic variations (NaCl presence). Fourier-transform infrared spectroscopy and field-emission scanning electron microscopy revealed surface functionalization of PVC and strong MGA adhesion, indicating that synergistic hydrogen bonding, halogen interactions, and metal-ligand coordination contribute to the removal mechanism. No hazardous elements were released during the process. This study demonstrates a scalable circular material approach that transforms industrial waste into high-performance magnetic materials for sustainable microplastic remediation.