Switchable surface Fe^II/III sites for water/sediment remediation through enhanced selective oxidation and ROS regulation: Performance, mechanism and application

Selective oxidation relying on high-valent iron-oxo species (Fe(IV/V)) is a promising way of effective organic decontamination. However, Fe(IV/V) formation and further purposeful reinforcement production are commonly insufficient and unsustainable. Herein, cerium (Ce) modification strategy was adopted for efficient micropollutants removal through boosting Fe(IV/V) generation. Kinetic rate of sulfamethoxazole (SMX) removal through peracetic acid (PAA) activation by FeCe-O-CN is 4.1-fold of that without Ce doping. Ce modification lowered energy barrier of the key reaction pathway (*OH→*O) during Fe(IV/V) formation and accelerated the exposure of the surface Fe^II site for Fe(IV) production. Steady-state concentration of Fe(IV) and Fe(V) in FeCe-O-CN/PAA process is 2.5 × 10^-8 and 9.7 × 10^-11 M with its corresponding contribution to SMX removal as 64 % and 36 %. Not only intensified SMX removal, Ce modification significantly reduced the toxicity of transformation products. Furthermore, FeCe-O-CN/PAA system satisfies favorable decontaminant in long-term runs, anti-interference, and significantly alleviated bioaccumulation in plants. This study provides a new insight into the association between Ce modification and Fe(IV/V) generation in PAA activation and offered a feasible way for enhanced selective oxidation.