School of Environment Science and Engineering, Donghua University, Shanghai, 201620, PR China.
School of Environment Science and Engineering, Donghua University, Shanghai, 201620, PR China; State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, Donghua University, Shanghai, 201620, PR China.
Chemosphere. 2022 Dec;308(Pt 2):136374. doi: 10.1016/j.chemosphere.2022.136374. Epub 2022 Sep 8.
Removal behavior of organic pollutants such as lignin in cotton pulp black liquor (CPBL) was investigated in precipitation followed by electrochemical oxidation (EO) using FeCl, Fe(SO), FeCl and FeSO as precipitants, electrolyte and catalysts. Based on comparison of precipitation efficacy of iron salts, spectroscopic techniques, thermodynamic equilibrium calculations and molecular dynamics (MD) simulations were used to provide insight into the interaction between iron cations and lignin. The results showed that FeCl achieved the highest removal of chemical oxygen demand (COD, 76.05%), UV (69.21%) and lignin (78.28%). Iron cationic complexation with lignin was identified as the key mechanism in precipitation. Fe was more active in binding to organic ligands mainly due to charge effect compared to Fe. The strong Fe-sulphate coordination affected the complexation with lignin. MD simulations showed the formation of inner sphere complexes of iron cations with deprotonated carboxyl and hydroxyl groups via bidentate and monodentate coordination. The removal efficiency of electrochemical oxidation (EO) as a post-treatment of the precipitation was dependent on iron salts. Removals of COD, UV and color can achieve 98.88%, 98.9% and 99.97% by FeCl precipitation and EO processes. The effluent reached the primary discharge standard specified in Integrated Wastewater Discharge Standard of China (GB8978-1996). FeCl demonstrated significant advantages in the removal of organic pollutants from cotton pulp black liquor in the combined process of precipitation and electrochemical treatment and may have practical application potential.
采用 FeCl、Fe(SO)、FeCl 和 FeSO 作为沉淀剂、电解质和催化剂，通过沉淀后电化学氧化（EO）研究了棉浆黑液（CPBL）中木质素等有机污染物的去除行为。通过比较铁盐的沉淀效果，利用光谱技术、热力学平衡计算和分子动力学（MD）模拟深入了解了铁阳离子与木质素之间的相互作用。结果表明，FeCl 对化学需氧量（COD，76.05%）、UV（69.21%）和木质素（78.28%）的去除效果最佳。确定铁阳离子与木质素的配位是沉淀过程中的关键机制。与 Fe 相比，Fe 由于电荷效应，更有利于与有机配体结合。强的 Fe-硫酸盐配位作用影响了与木质素的配位。MD 模拟表明，铁阳离子通过双齿和单齿配位与去质子化的羧基和羟基形成内球配合物。沉淀后 EO 作为后处理的电化学氧化（EO）的去除效率取决于铁盐。采用 FeCl 沉淀和 EO 工艺，COD、UV 和色度的去除率可达到 98.88%、98.9%和 99.97%。出水达到《中华人民共和国国家综合污水排放标准》（GB8978-1996）一级排放标准。FeCl 在沉淀和电化学处理联合工艺中对棉浆黑液中有机污染物的去除具有显著优势，可能具有实际应用潜力。
