Multiple regeneration of "high iron" alginate composite gel beads for rapid treatment of dye wastewater.

Water pollution, particularly from dye contaminants, has become a critical global issue, driving the demand for efficient treatment technologies such as persulfate-based advanced oxidation processes. In our study, we developed a novel chitosan-modified calcium alginate gel as a scaffold for heterogeneous Fenton catalysis. Through grafting ethylenediaminetetraacetic acid onto the amino groups within the gel backbone and subsequent loading of Fe2+, we developed CASGMC, a "high iron" alginate gel capable of efficiently absorbing and releasing Fe2+. Additionally, 3D RGO@Cu2S-MoS2 was incorporated into the gel system to enhance catalytic efficiency and suppress Fe3+ accumulation, thereby extending the gel's service life. CASGMC exhibited excellent mechanical stability and structural integrity, achieving an impressive 98.8 % removal of rhodamine B within 15 min. Furthermore, its regeneration process was straightforward, with catalytic activity restored simply by immersion in an Fe2+ solution, allowing for up to ten cycles of reuse. Notably, even after 1032 h of continuous operation, a CASGMC-filled purification column maintained an 88.67 % removal efficiency of rhodamine B, demonstrating its long-term applicability. This study not only enhances the mechanical durability and reusability of alginate-based catalysts but also provides a promising strategy for sustainable wastewater treatment using iron-loaded gel materials.