Hierarchical porous tannic-acid-modified MOFs/alginate particles with synergized adsorption-photocatalysis for water remediation

Organic dye contaminants pose increasing threats to water ecological systems and global sustainability. Rational development of functional particles with adsorption-catalysis synergy is envisioned as a powerful route for enhanced water remediation. Here, hierarchical porous MOF-integrated alginate particles with synergized adsorption and photocatalytic degradation is developed for effective water remediation. The particles exhibit unique mesh-like Ca-alginate (CaAlg) networks with incorporated macro-/micro-porous zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, both modified with negatively-charged tannic acid (TA). The TA-modified mesh-like CaAlg (CaAlg@TA) networks serve as highly porous absorbents, while the TA-modified ZIF-8 (ZIF-8@TA) nanoparticles serve as both hierarchical porous nano-absorbents and photoactive nano-catalysts. This combination simultaneously harnesses the advantages of CaAlg@TA networks and ZIF-8@TA nanoparticles to achieve adsorption-photocatalysis synergy for efficient water remediation. As demonstrated by removal of toxic and carcinogenic dye methylene blue (MB), these particles show much higher performances with fast adsorption and high capacity (1277 mg g⁻¹), as compared to control group particles without adsorption-photocatalysis synergy. Meanwhile, the adsorption-photocatalysis synergy largely suppresses undesired secondary water contamination from the MB-adsorbed particles, and benefits particle regeneration to achieve good reusability for repeated MB removal (>95.5 % for 10 cycles). This work provides a simple and flexible route for rational fabrication of MOF-integrated particles with adsorption-photocatalysis synergy, and thus may open up new horizons for developing advanced functional particles for effective water remediation.