Both Fe(II)/free chlorine (Fe(II)/FC) and Fe(II)/peroxymonosulfate (Fe(II)/PMS) have a faster reactive species formation rate than the classic Fenton process, so their efficiencies of removing pollutants are better than that of the Fenton process. In this study, we compared the differences in the mechanisms and kinetics of iopamidol (IPM) degradation by Fe(II)/FC and Fe(II)/PMS. Although the production rate of reactive species of the two processes is at the same level (10⁴ M⁻¹ s⁻¹), the Fe(II)/PMS process performed better regarding IPM removal. Reactive chlorine species (RCS) were the major contributor to the degradation of IPM (73.8%) by Fe(II)/FC, and hydroxyl radicals (HO^•) and sulfate radicals (SO₄^•–) contributed 50.7% and 49.3% to the degradation of IPM by Fe(II)/PMS, respectively. Fe(IV) showed low contributions (<0.1%) to the degradation of IPM during the Fe(II)/FC and Fe(II)/PMS processes because of the low values of k_{Fe(IV), IPM} ((25 ± 5) M⁻¹ s⁻¹) and the low steady-state concentration of Fe(IV) in the Fe(II)/FC ((5.1 ± 0.7) × 10⁻⁸ M) and Fe(II)/PMS processes ((2.2 ± 0.09) × 10⁻⁸ M) at pH 3. Based on density functional theory (DFT) calculations and the MS results, the transformation pathway of IPM has been confirmed to mainly occur on chains B and B’ and the iodine group in between. The formation of disinfection by-products (DBPs) indicates that the Fe(II)/PMS process has lower environmental hazards. In general, we should pay more attention to the type of active species to evaluate the Fenton-like process. This study provides a basis for choosing a suitable alternative to the Fenton process and understanding the process in the Fenton-like procedure.

Fe(II)/游离氯 (Fe(II)/FC) 和 Fe(II)/过氧单硫酸盐 (Fe(II)/PMS) 均比经典的 Fenton 工艺具有更快的活性物种形成速度，因此它们去除污染物的效率更高优于芬顿工艺。在本研究中，我们比较了 Fe(II)/FC 和 Fe(II)/PMS 对碘帕醇 (IPM) 降解机制和动力学的差异。尽管两种工艺的反应性物质的生产速率处于相同水平（10 ⁴ M ^-1 s ^-1），但Fe(II)/PMS工艺在IPM去除方面表现更好。^{活性氯物质 (RCS) 是 Fe(II)/FC 以及羟基自由基 (HO •} ) 和硫酸根自由基 (SO ₄ ^•– ) 降解 IPM (73.8%) 的主要贡献者) 分别对 Fe(II)/PMS 对 IPM 的降解贡献了 50.7% 和 49.3%。由于k _Fe(IV)、IPM ((25 ± 5) M ^-1 s ^-1 ) 和 Fe(II)/FC ((5.1 ± 0.7) × 10 ^-8 M) 和 Fe(II)/PMS 过程中的低稳态 Fe(IV) 浓度( (2.2 ± 0.09) × 10 ^-8M) 在 pH 3 时。基于密度泛函理论 (DFT) 计算和 MS 结果，已确认 IPM 的转化途径主要发生在链 B 和 B' 以及其间的碘基团​​上。消毒副产物 (DBP) 的形成表明 Fe(II)/PMS 工艺具有较低的环境危害。一般来说，我们应该更多地关注活性物种的类型来评估类芬顿过程。本研究为选择合适的 Fenton 过程替代方案和理解 Fenton 样过程中的过程提供了基础。