In this work, Fe(II)/Peroxymonosulfate (PMS) treatment with dual functionality of pre-oxidation and coagulation was applied to enhance the removal of alkali lignin in water. The removal efficiency of alkali lignin (2 g/L) could reach ∼ 99% at an optimal dosage of [Fe(II)] = 2.4 mM and [PMS] = 7.8 mM, which was efficiently superior than that using ferric and polymeric coagulant individually. Pre-oxidation, involving hydroxyl radical (•OH) and sulfate radical (SO₄^•−), has been demonstrated to play a crucial role in both oxidative degradation (∼30%) and reducing the molecular weight and hydrophilicity of lignin. Meanwhile, the formation of polynuclear Fe-hydroxide complexes was also fostered, which in turn greatly contribute to the removal of lignin through an enhanced coagulation mechanism. The reductive units present in alkali lignin was demonstrated to initiate a dynamic transition between Fe(III) and Fe(II) by donating electrons. This redox activity is anticipated to continuously promote the formation of electro-neutral and loose flocs, thereby resulting in an enhanced coagulation performance. Furthermore, ultrafiltration (UF) was also demonstrated as a viable liquid/solid separation method following Fe(II)/PMS treatment, effectively promoting membrane flux recovery rate to ∼90%. This highlights the remarkable potential of this method when combined with other treatment processes. This study aims to offer a complementary strategy for remediating alkali lignin wastewater while advancing the fundamental understanding of redox-reaction enhanced in-situ coagulation in water treatment applications.

在这项工作中，采用具有预氧化和混凝双重功能的Fe(II)/过一硫酸盐(PMS)处理来增强水中碱木质素的去除。在[Fe(II)] = 2.4 mM和[PMS] = 7.8 mM的最佳用量下，碱木质素（2 g/L）的去除效率可达到~ 99%，明显优于使用铁和聚合物混凝剂的去除效率单独。预氧化，涉及羟基自由基（•OH）和硫酸根（SO ₄ ^•−），已被证明在氧化降解（〜30％）和降低木质素的分子量和亲水性方面发挥着至关重要的作用。同时，还促进了多核铁氢氧化物络合物的形成，这反过来又极大地有助于通过增强的混凝机制去除木质素。碱木质素中存在的还原单元被证明可以通过提供电子来引发 Fe(III) 和 Fe(II) 之间的动态转变。这种氧化还原活性预计将持续促进电中性和松散絮凝体的形成，从而增强混凝性能。此外，超滤（UF）也被证明是 Fe(II)/PMS 处理后可行的液/固分离方法，有效地将膜通量恢复率提高至约 90%。这凸显了该方法与其他处理工艺相结合时的巨大潜力。本研究旨在为修复碱木质素废水提供补充策略，同时增进对氧化还原反应增强的基本理解水处理应用中的原位混凝。