Structure-directed design of biomass–metal–organic framework composites for As(V) removal in specific water environments

A structure oriented biomass MOF design strategy is developed. • Two composites enable fast kinetics and high capacity adsorption. • Distinct mass transfer behaviors are governed by pore architecture. • A new paradigm for scenario-specific adsorbent design is proposed. Arsenate contamination in aquatic environments poses a serious threat to ecosystem safety and human health. Developing sustainable biomass-derived adsorbents with targeted adsorption performance for different water treatment scenarios remains challenging. Herein, two biomass–metal–organic framework (MOF) composites were constructed by matching biomass-derived pore architectures with MOF active-site chemistry for As(V) removal. Wood–MOF was fabricated by in situ growth of NH₂-MIL-88(Fe) within the hierarchical channels of delignified wood, while BC–MOF was obtained by integrating UiO-66(Zr)–MIL-88(Fe) dual-metal centers into the mesoporous framework of straw-derived biochar. The two composites exhibited high experimental As(V) adsorption capacities of 350.16 and 364.81 mg/g, respectively, with adsorption dominated by monolayer chemical interactions at accessible active sites. Fixed-bed experiments revealed distinct continuous-flow behaviors: Wood–MOF enabled rapid mass transfer under high-flow conditions due to its interconnected wood-derived channels, whereas BC–MOF exhibited more stable breakthrough behavior and stronger phosphate resistance owing to its mesoporous framework and Fe/Zr dual-metal active sites. The different dynamic adsorption behaviors highlight the importance of coordinating biomass-derived transport architectures with MOF-based adsorption chemistry for continuous-flow arsenic removal. Real water adsorption experiments, regeneration tests, metal leaching analysis, and spectroscopic characterization further demonstrated the practical applicability and structural stability of both composites. Spectroscopic analyses indicated that As(V) immobilization involved oxygen-containing groups, ligand exchange, and coordination interactions with Fe/Zr active centers. This study provides a biomass–MOF design strategy by coupling biomass-derived architectures with MOF chemistry, offering a promising approach for developing scenario-oriented adsorbents for efficient arsenic remediation. Download: Download high-res image (201KB) Download: Download full-size image