Development of a Double-Metal-Cross-Linked Hydrogel Filler as a Stable Heterogeneous Fenton Catalyst for Organic Wastewater Degradation

Heterogeneous Fenton catalysts for wastewater treatment have garnered substantial attention due to their reusability and separability in engineering applications. Herein, we designed a millimeter-scale spherical hydrogel bead-based Fenton catalyst (PVA/Alg–Fe–Ce) with poly(vinyl alcohol)/Ce-alginate cross-linked hydrogel as the backbone and the iron site as the H₂O₂ activation center using a sol–gel method. The catalyst PVA/Alg–Fe–Ce with a stable double-network structure not only possessed good mechanical properties (0.8 MPa compressive stress at 50% compressive strain) and chemical stability (iron leakage of 0.14 mg/L) during the Fenton reaction but also exhibited fast catalytic degradation capacity for organic pollutants (rhodamine B, RhB) within 20 min. The results of the toxicity assessment showed that ecotoxicity could be reduced. More importantly, a continuous-flow Fenton reactor packed with PVA/Alg–Fe–Ce beads could efficiently treat 30 bed volumes of organic wastewater with over 90% removal of RhB, which may provide a strategy for developing durable, efficient, and environment-friendly heterogeneous Fenton catalysts based on a high-strength hydrogel system convenient for treating organic sewage.