Structural ferrous hydroxyl complex unlocks neutral-pH Fenton-like chemistry via multi-pathway ROS generation from nano calcium peroxide.

Authors

Qian-Qian Jia, Rou Liu, Shiyu Wang, Yingmin Liu, Yuwei Gu, Yafei Wang, Yumei Chen, Xiujie Wang, Tongyi Yang, Xin Yan, Li-Zhi Huang

Published in

Environmental research. Pages 125305. Jul 25, 2026. Epub Jul 25, 2026.

Abstract

Conventional Fenton technology is severely bottlenecked by its strict dependence on highly acidic environments. This study develops an acid-free Fenton-like strategy utilizing a structural Fe(II) source (ferrous hydroxyl complex, FHC) to activate a solid H₂O₂ precursor (nano-calcium peroxide, nCP). Under circumneutral conditions, the FHC-nCP system rapidly degrades >90% of Acid Orange 7 (AO7) within just 5 min. Notably, the system exhibits a negative apparent activation energy (-23.18 kJ·mol^-1), indicating an unconventional exothermic, surface-mediated degradation pathway. Comprehensive mechanistic investigations-including quenching, chemical probes, and EPR spectroscopy-unveil a significant reaction paradigm shift: •O₂^- and ¹O₂, rather than the classical •OH, decisively dominate the degradation process (contributing >85%). Meanwhile, electrochemical analyses (CV and OCP) firmly exclude direct electron transfer. Mechanistically, controlled H₂O₂ release from nCP hydrolysis regulates a robust Fe(II)/Fe(III)/Fe(IV) cycle and, alongside co-released O₂, triggers the synergistic generation of four reactive oxygen species (ROS). Also, hydrogen bonding (O-H···O) acts as the primary interfacial interaction bridging FHC and nCP, while density functional theory (DFT) calculations pinpoint the specific AO7 sites vulnerable to •O₂^-/¹O₂ attack. Environmentally, Fe speciation analysis demonstrates that ∼53% of total iron is converted into readily settleable sludge, significantly curtailing secondary pollution compared to homogeneous Fenton systems. This work establishes a novel paradigm for neutral-pH, multi-pathway Fenton-like chemistry and provides design principles for pH-adaptive advanced oxidation technologies.

PMID:
42501933
Bibliographic data and abstract were imported from PubMed on 26 Jul 2026.

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