Synergistic adsorption-oxidation of phenol by a magnetically recoverable LNC/MMT-stabilized NZVI composite

Phenolic wastewater remains a critical environmental concern owing to its high toxicity and resistance to natural attenuation. To overcome the inherent drawbacks of bare nano-zero-valent iron (NZVI)-namely severe agglomeration and rapid surface passivation-we designed a novel ternary composite (LNC/MMT@NZVI) by immobilizing NZVI particles onto a lignocellulose/montmorillonite (LNC/MMT) binary support via liquid-phase reduction. This strategy achieved excellent NZVI dispersion and generated a mesoporous architecture with markedly enhanced thermal stability, as confirmed by N₂ adsorption-desorption, XRD, FTIR, SEM-EDS, TEM, TG-DSC, and VSM analyses. The composite exhibited an outstanding phenol adsorption capacity of 127.58 mg g^-1 under optimized conditions (pH 8, 50 °C, 240 min). Kinetic and isotherm studies revealed that phenol removal follows the pseudo-second-order model (R ² = 0.9857) and Langmuir isotherm (R ² = 0.9999), indicating a chemisorption-dominated monolayer process. XPS and EPR spectroscopic evidence unambiguously demonstrated that the embedded Fe⁰ initiates a sustained Fenton-like redox cycle, generating hydroxyl radicals (·OH) as the predominant reactive species, while the LNC/MMT support concurrently enriches phenol molecules near the active sites via hydrogen bonding and surface complexation. This synergistic integration of adsorptive enrichment and catalytic oxidation not only overcomes the intrinsic limitations of standalone NZVI but also provides a highly efficient, magnetically recoverable platform for treating recalcitrant organic wastewater.