Mechanistic insights into the influence of dissolved organic matter in stormwater runoff on the TOrCs degradation by PB-Fe@CN: Reaction kinetics and degradation pathways

Abstract

Dissolved organic matter (DOM) in stormwater runoff significantly impacted the degradation efficiency of trace organic pollutants (TOrCs) by heterogeneous catalytic systems, but its quantitative elucidation and reaction kinetics remained underexplored. In this work, the influence of DOM from stormwater runoff on TOrCs purification by a phosphorus, boron, and nitrogen-doped iron@porous carbon catalyst (PB-Fe@CN) to activate peroxymonosulfate was quantitatively investigated. Bimolecular reaction rate constants were determined to quantify the interactions between DOM/TOrCs and reactive oxygen species (ROS). The PB-Fe@CN catalyst exhibited great efficiency (71.2 ∼ 100 %) in degrading TOrCs, but DOM significantly reduces ROS steady-state concentrations of the system through competitive adsorption and radical scavenging effects. Reaction kinetic analysis showed that DOM’s scavenging effect on •OH (3.05 × 10³ ∼ 3.21 × 10³ L·mgC^-1·s⁻¹) was significantly stronger than that on SO₄^•− (2.54 × 10² ∼ 2.75 × 10² L·mgC^-1·s⁻¹). Additionally, DFT calculations were employed to elucidate the degradation pathways and toxicity changes of TOrCs under DOM interference in stormwater runoff. Finally, we designed a feasible application scenario for PB-Fe@CN coupling multi-layer infiltration systems and bioretention facilities to maximize the potential of PB-Fe@CN to degrade TOrCs in stormwater runoff. This study provides a novel quantitative perspective on the mechanism of DOM in heterogeneous catalytic systems and a technical reference for the efficient resource utilization of stormwater.