Polyhalogenated carbazoles (PHCs) are an emerging class of halogenated organic contaminants, which have widespread occurrence and dioxin-like toxicities. However, effective approaches for PHCs degradation are lacking. Recently, persulfate based advanced oxidation processes (AOPs) are considered as promising technologies for aqueous organic contaminants destruction due to the high reactivity and selectivity of sulfate radical. In this study, the degradation kinetics and mechanism of PHCs by sulfidated zero-valent iron/peroxymonosulfate (S-ZVI/PMS) system were investigated. The pseudo-first-order rate constants (k) of 11 PHCs ranged from 0.051 to 1.623 min⁻¹. Seventeen quantum chemical descriptors were calculated based on density functional theory (DFT). By using correlation analysis, principal component analysis (PCA) and multiple linear regression (MLR), a quantitative structure activity relationship (QSAR) model was developed: log k = 8.681 ×f(0)_n + 0.231 × #X – 0.593, where f(0)_n and #X represent the minimum value of Fukui index for radical attack and the halogen number, respectively. The correlation analysis and model interpretation indicate that radical addition is the dominant reaction pathway for PHCs instead of single electron transfer (SET). Results of validation and applicability domain indicate that the developed QSAR model has good robustness and satisfactory predictive performance. Finally, the degradation kinetics of five frequently detected but commercially unavailable PHCs were predicted. The overall purpose of this study is to develop a predictive model and interpret the degradation mechanism of PHCs in PMS-AOP, which is difficult to be distinguished by experimental results alone.

多卤代咔唑（PHCs）是一类新兴的卤代有机污染物，具有广泛的发生和类似二恶英的毒性。然而，缺乏有效的 PHCs 降解方法。最近，由于硫酸根的高反应性和选择性，基于过硫酸盐的高级氧化工艺 (AOP) 被认为是用于破坏水性有机污染物的有前景的技术。在本研究中，研究了硫化零价铁/过氧单硫酸盐 (S-ZVI/PMS) 体系对 PHCs 的降解动力学和机理。11 个 PHC 的伪一级速率常数 (k) 范围为 0.051 至 1.623 min ^-1. 基于密度泛函理论 (DFT) 计算了 17 个量子化学描述符。通过相关分析、主成分分析 (PCA) 和多元线性回归 (MLR)，建立了定量结构活性关系 (QSAR) 模型：log k = 8.681 ×f(0) _n + 0.231 × #X – 0.593，其中f(0) _n和#X 分别代表自由基攻击的福井指数和卤素数的最小值。相关性分析和模型解释表明，自由基加成是 PHC 的主要反应途径，而不是单电子转移 (SET)。验证和适用域结果表明，所开发的 QSAR 模型具有良好的鲁棒性和令人满意的预测性能。最后，预测了五种经常检测到但商业上不可用的 PHC 的降解动力学。本研究的总体目的是建立一个预测模型并解释 PMS-AOP 中 PHCs 的降解机制，仅凭实验结果很难区分。