Facile synthesis of α-Fe2O3/ Fe3O4 hybrid adsorbent with tailored affinity sites for high-efficiency microplastics capture

There is growing attention in the removal of microplastics (MPs) from aquatic environment because of their toxicity and difficulty in degradation. Magnetic Fe 3 O 4 is a potential material for MP removal, however, for fabrication of high-efficiency Fe 3 O 4 -based adsorbents, the alkaline synthesis conditions and weak affinity toward MPs must to be addressed. In this study, we developed magnetic α-Fe 2 O 3 /Fe 3 O 4 hybrid adsorbents (MFes) with engineered affinity sites via a facile one-pot synthesis method. During the material formation process, melamine acted as both a nitrogen source for creating N-modified polar adsorption sites and an inducer for formation of α-Fe 2 O 3 /Fe 3 O 4 phase interfaces. The α-Fe 2 O 3 /Fe 3 O 4 phase interfaces provided additional active sites, as evidenced by the enhanced microplastic adsorption performance. The MFe-1.6–100 achieved 92.3 % polystyrene removal at low adsorbent dosage 0.2 g L −1 and showed rapid adsorption kinetics within 25 min, which is superior to most reported values. After five cycles, the removal efficiency could still retain 90 %. Additionally, MFe-1.6–100 exhibited remarkable ion-tolerance for Cl - and NO 3 - . These performances suggest its potential applicability for MPs capture in aquatic environments.