Simultaneous Deep Dehalogenation and Mineralization of Refractory Halogenated Organics in the ZVI-Water System: A...

The synergistic redox process has emerged as an innovative strategy for the complete mitigation of refractory halogenated organics. However, constructing an in situ oxidation-reduction coupling in the ZVI-water system remains challenging due to cross-quenching. Herein, a bifunctional ZVI-NFNi catalyst was engineered by incorporating NH4F to reconstruct the hydrogen-bond network of adsorbed water, which created a micropartition to couple atomic hydrogen (H*) reduction with active oxygen (•OOH) oxidation. Experimental and theoretical analyses revealed that NH4F disrupted tetrahedral H-bonding of H2O via strong F/N-H···[OH···OH2]δ+ interactions, thereby accelerating H2O splitting and H* generation, which dramatically enhanced nucleophilic dechlorination of 4-chlorophenol (4-CP) to 93.8%, with a rate constant (0.87 min-1) of 12.2 times higher than that of ZVI-Ni. More significantly, the hydrogen bond electrostatic gradients of NH4F on ZVI-NFNi enhanced *O stabilization at N sites, while H* was trapped at F sites. These micropartitions promoted H*-driven *O reduction to •OOH (H* + O2 → *OOH), thus oxidizing the residual carbon skeleton and significantly raising the mineralization efficiency of 4-CP to 87.6% (vs 29.1% for ZVI-Ni). This study innovatively integrates in situ redox partition in ZVI-H2O systems through the reconstruction of hydrogen-bond networks, offering a synergistic strategy for the complete detoxification of refractory halogenated pollutants.