Supporting binary metal-organic framework derivatives within wood-based activated carbon boosts rapid adsorption of sulfamethoxazole from aqueous solutions

Binary metal-organic framework (BMOF) derivatives have emerged as promising adsorbents for the removal of hazardous antibiotics from water. However, most proposed adsorbents often exhibit low adsorption capacities due to self-aggregation, structural instability, and challenges associated with separation in aqueous solution. Herein, we present a highly efficient ZrO2/Fe3O4@AC adsorbent (AC denotes wood-based activated carbon), featuring UiO-66(Zr)/MIL-101(Fe) BMOF-derived Zr-Fe bimetal oxides nanoparticles embedded within porous carbon scaffolds. In-situ anchoring of MOF-on-MOF derivatives onto AC significantly enhances pore complexity, specific surface area, and the number of active sites. The results indicated that the adsorption behavior was best characterized by the Langmuir isotherm and the pseudo-second-order model. Remarkably, ZrO2/Fe3O4@AC achieved rapid adsorption equilibrium within 15 min, demonstrating a remarkable adsorption capacity of 229.7 mg/g. Thermodynamic analysis showed that the adsorption process is exothermic and occurs spontaneously. Furthermore, the adsorbents were readily regenerated through simple washing with methanol, maintaining over 95 % efficiency after five consecutive adsorption-desorption cycles. Mechanism analysis divulged that the co-presence of iron and zirconium species in activated carbon significantly enhanced the adsorptive capacity for SMX. This enhancement is ascribed to the introduction of additional adsorption sites and the facilitation of oxygen-rich functional groups. The immobilization of SMX macromolecules on the surface of ZrO2/Fe3O4@AC occurred through charge-assisted hydrogen bonding, pi-pi interaction with graphitized carbon, and electrostatic attractions. This study presents innovative strategies for synthesizing wood-based activated carbon-supported BMOF derivative adsorbents specifically designed for the rapid adsorption of sulfamethoxazole antibiotics.