As an oxidant, peracetic acid (PAA) is gradually being used in advanced oxidation processes (AOPs) for pollutant degradation. In this study, bimetallic synergistic activation effect and the impact of sulfonamides (SAs) structure on degradation efficiency are firstly researched in the system of activating PAA by binary layered double hydroxide (CoFe-LDH). Compared with LDH composed of a single metal, CoFe-LDH bimetallic LDH can promote the electrochemical performance of the catalyst and improve the electron transfer ability, Fe atoms can accelerate the conversion of Co from +3 to +2 valence state, which can improve the activation ability of PAA. Multiple reactive oxygen species (ROS) (●OH, acetyl(per)oxyl radicals (R-O●) and Fe(IV)) are involved in Co2Fe1-LDH/PAA system and R-O● is the dominant role in degrading SAs. These ROS jointly participate in the degradation of SAs with various substituents, resulting in different removal efficiencies. Specifically, the order of degradation rate is SIZ (99.5%) &gt; SMX (95.3%) &gt; STZ (88.9%) &gt; SPD (86.4%) &gt; SMR (82.3%) &gt; SDZ (78.7%) &gt; SA (75.8%), showing that SAs with five-membered heterocyclic substituents are more sensitive than SAs with six-membered heterocyclic substituents. Density functional theory (DFT) calculations indicated that SAs with high EHOMO, low energy gap (ΔE = ELUMO – EHOMO), and low vertical ionization potential (VIP) are more vulnerable to be attacked. The unique SO2 extrusion product in degrading six-membered SAs may hinder their degradation and increase the biological toxicity of six-membered SAs. The new knowledge obtained in this study will facilitate further research about bimetallic synergic effect and influence of pollutant structure on degradation efficiency and products and biotoxicity in PAA activation system.

Efficient degradation of sulfonamides (SAs) in CoFe-LDH/peracetic acid (PAA) system: Bimetallic synergic effect and the effect of contaminant structure on degradation efficiency

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