Jellyfish-inspired alginate composite hydrogel filter prepared by macro-micro double bionic strategy for efficient water purification

Recently, research on hydrogel materials with a porous structure and superior water absorption capabilities significantly grown. However, the hydrogel under gravity-driven separation conditions often exhibit an unstable pore structure, poor mechanical properties, and limited functionality. To this end, this work presents a novel approach that combines a macro-micro double bionic strategy with a triple crosslinking method to develop a multifunctional alginate composite hydrogel filter (2%-SA-κ-CG-PVA-Ca²⁺, 2%-SKP-Ca²⁺ for short) with a stable pore structure and superior mechanical properties, which possessed an umbrella-shaped structure resembling that of jellyfish. The 2%-SKP-Ca²⁺ filter was synthesized using polyvinyl alcohol (PVA) as a stable structure-directing agent, and sodium alginate (SA) and κ-carrageenan (κ-CG) as polymer hydrogels. The distinctive umbrella-shaped hydrogel of 2%-SKP-Ca²⁺ filter, formed through the triple crosslinking method, overcomes the limitations of unstable pore structure and poor durability seen in hydrogels prepared by traditional crosslinking methods. Furthermore, the utilization of the 2%-SKP-Ca²⁺ filter in water treatment demonstrates its good selective permeability, excellent resistance to fouling, and extended longevity, which enables it to simultaneously achieve the multifunctional water purification and the coating of multi-substrate anti-fouling coatings. Therefore, not only does this research provide an efficient, multifunctional, highly pollution-resistant preparation method for designing a new filter, but it also confirms the application prospect of the macro-micro dual bionic strategy developed in this study in complex water treatment.