Enhancing microplastics capture in high-flux aquatic environments via the fabrication of a ZnCo-bimetallic-augmented calcium alginate carbon aerogels

Stable framework-structured materials are effective adsorbents for mitigating microplastics (MPs) pollution in the water ecosystem. Calcium alginate (Alg), a plentiful marine biomass with functional groups and high stability, shows great potential as a framework precursor. Herein, we fabricated ZnCo-bimetallic-augmented calcium alginate carbon aerogels (ZnCo/Alg@CAs) with a monolithic structure via in situ synthesis of ZnCo-ZIF on Alg matrix combined with thermal treatment. The in situ synthesis strategy effectively suppressed metal ion aggregation and enhanced the structural stability of MOF-derived carbon materials. Remarkably, ZnCo/Alg@CAs exhibited a high water flux (4431 L/(h·m)), rapid adsorption kinetics (100 min), and high removal capacities (1673-1989 mg/g) for various MPs, outperforming reported adsorbents. Moreover, ZnCo/Alg@CAs showed anti-interference to interfering ions, acid/alkali, and humic acid. Compared to powdered materials, the monolithic structure of ZnCo/Alg@CAs enabled direct integration into closed-loop systems coupled with peristaltic pumps, achieving dynamic removal of MPs during water purification processes. Based on the analytical results from FTIR, XPS, and Density Functional Theory calculations, the primary adsorption mechanism in this system involves a synergistic effect between hydrogen bonding, p-π stacking interaction, and physical retention. This research is anticipated to pave new avenues for the sustainable treatment of MPs from large volumes of water in the aqueous environments.