ZIF-8-Supported Sulfidated Nanoscale Zero-Valent Iron: Synergistic Effects for Enhanced Trichloroethylene Degradation

Trichloroethylene (TCE) is a pervasive groundwater contaminant, yet the practical application of nanoscale zero-valent iron (nZVI) is often limited by particle aggregation, rapid surface oxidation, and inefficient utilization of reactive electrons. Here, we developed a support–sulfidation coupled design to improve TCE dechlorination by integrating ZIF-8-enabled contaminant enrichment and dispersion with sulfidation-enabled surface-state regulation. A ZIF-8-supported sulfidated nZVI composite (ZIF-8@S-nZVI) was synthesized and systematically compared with nZVI, S-nZVI, and ZIF-8@nZVI. Among the tested materials, ZIF-8@S-nZVI exhibited the fastest TCE removal, the highest ethylene formation, and the highest chloride release, indicating the most effective dechlorination performance rather than merely adsorption-driven apparent removal. The optimal Fe:ZIF-8 mass ratio was 6:1. The composite also maintained high dechlorination capability over 20–40 °C, pH 6–9, and initial TCE concentrations of 10–40 mg/L, although 20 °C, near-neutral pH, and lower pollutant loading were kinetically more favorable. Multiscale characterization by FT-IR, N2 adsorption–desorption and BET, XRD, EDS, SEM, and XPS indicated that ZIF-8 mitigated particle aggregation and retained partial pore accessibility, whereas sulfidation was associated with a more persistent Fe(II)-rich surface state after reaction. Together, these coupled effects promoted local TCE enrichment and sustained interfacial transformation. This study provides mechanistic insight and practical guidance for the rational design of MOF-supported sulfidated iron materials for chlorinated-solvent-contaminated groundwater remediation.