Free chlorine (HOCl) and monochloramine (NH₂Cl) are two of the most commonly used water disinfectants in water treatment; however, the capability of rapid mixing of HOCl into NH₂Cl to induce oxidative reactions for efficient removal of contaminants remains largely unknown. In this study, 1,4-dioxane (1,4-D) removal was quantified during the rapid mixing of HOCl into NH₂Cl, to evaluate the effects of solution pH and HOCl-to-NH₂Cl ratio, and to identify mechanisms by which reactive species are generated in the system. Results showed that the highest 1,4-D removal was observed at the near-neutral pH of 6 with the HOCl-to-NH₂Cl molar ratio of 1. Hydroxyl radical (HO^•) contributed to 60–70 % of 1,4-D degradation and its generation was initiated by the hydrolytic decay of NH₂Cl and NHCl₂ upon HOCl addition to NH₂Cl with rapid mixing, and subsequent transformation of peroxynitrite (ONOO^-) and peroxynitrous acid (ONOOH). The results also confirmed that the presence of dissolved oxygen was required to form ONOO^-/ONOOH, and ONOO^- was a crucial precursor for reactive radical generation. These findings provide insight into the reaction mechanism associated with the system of rapidly mixed HOCl into NH₂Cl with the potential optimization and application for efficient trace organics removal in water treatment and reuse.

游离氯（HOCl）和一氯胺（NH ₂ Cl）是水处理中最常用的两种水消毒剂；然而，HOCl 快速混合到 NH ₂ Cl 中以诱导氧化反应以有效去除污染物的能力仍然很大程度上未知。在本研究中，量化了 HOCl 与 NH ₂ Cl 快速混合过程中 1,4-二恶烷 (1,4-D) 的去除情况，以评估溶液 pH 值和 HOCl 与 NH ₂ Cl 比的影响，并确定在系统中产生活性物质的机制。结果表明，在接近中性的 pH 值为 6 且 HOCl 与 NH 2 Cl 的摩尔比为 1 时，1,4-D 的^去除率_最高。)促成了 60-70% 的 1,4- _D降解，其生成是由 NH ₂ Cl和NHCl ₂的水解衰变引发^的和过氧亚硝酸（ONOOH）。结果还证实，溶解氧的存在是形成 ONOO ^- /ONOOH 所必需的，而 ONOO ^-是反应性自由基产生的关键前体。这些发现为深入了解与快速混合 HOCl 到 NH ₂ Cl 的系统相关的反应机制提供了潜在的优化和应用，以在水处理和再利用中有效去除痕量有机物。