Zheng Ruyi, Zhao Ruihan, Yang Tianwen, Wu Pan, Zhu Jian, Liao Peng
College of Resources and Environment Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guizhou University, Guiyang 550025, China.
College of Resources and Environment Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guizhou University, Guiyang 550025, China.
J Hazard Mater. 2025 Sep 5;495:139033. doi: 10.1016/j.jhazmat.2025.139033. Epub 2025 Jun 23.
Natural organic matter (NOM) colloids are frequently encountered at the anoxic-oxic interface in subsurface environments. Their surface-rich functional groups and redox capacity exert a significant influence on the fate and transport of Fe and Cd in aquatic systems. The present study demonstrated that stable Fe-HA-Cd colloids formed in both anoxic and oxic environments, with hydrodynamic diameters stabilized at 97.4-134.5 nm at an HA concentration of 64.3 mg C/L. The incorporation of Fe promoted the formation of Cd colloids on the surface of HA to a certain extent. However, the high concentration of Fe(II) (C/Fe <22.4) and Fe(III) (C/Fe<7.0) in both anoxic and oxic conditions inhibited the formation of Cd colloid by competitive adsorption and co-precipitation, respectively. Furthermore, the redox effect in the oxic transformation of Fe(II)-HA-Cd(II) colloid led to the release of truly dissolved Cd from colloidal particles to the water. The aggregation kinetics and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory demonstrated that Fe-HA-Cd colloids reduced particle stability compared to HA-Cd(II) colloids. Additionally, the depolymerization behavior of Fe-HA-Cd colloids during aggregation exhibited variability under different conditions, particularly with regard to the time-dependent size effect. This study offers detailed data on the formation, oxidative transformations, and stability of Fe-HA-Cd colloids in anoxic-oxic environments rich in organic matter. The findings provide valuable insights into Cd partitioning and environmental behavior between particulate and dissolved states, essential for understanding Cd pollution and advancing effective remediation strategies.
天然有机物（NOM）胶体在地下环境的缺氧-好氧界面经常出现。其富含表面的官能团和氧化还原能力对水生系统中Fe和Cd的归宿及迁移有重大影响。本研究表明，在缺氧和好氧环境中均形成了稳定的Fe-HA-Cd胶体，在HA浓度为64.3 mg C/L时，流体动力学直径稳定在97.4 - 134.5 nm。Fe的掺入在一定程度上促进了Cd胶体在HA表面的形成。然而，缺氧和好氧条件下高浓度的Fe(II)（C/Fe <22.4）和Fe(III)（C/Fe<7.0）分别通过竞争性吸附和共沉淀抑制了Cd胶体的形成。此外，Fe(II)-HA-Cd(II)胶体在好氧转化中的氧化还原作用导致真正溶解的Cd从胶体颗粒释放到水中。聚集动力学和Derjaguin-Landau-Verwey-Overbeek（DLVO）理论表明，与HA-Cd(II)胶体相比，Fe-HA-Cd胶体降低了颗粒稳定性。此外，Fe-HA-Cd胶体在聚集过程中的解聚行为在不同条件下表现出变异性，特别是在与时间相关的尺寸效应方面。本研究提供了关于富含有机物的缺氧-好氧环境中Fe-HA-Cd胶体的形成、氧化转化和稳定性的详细数据。这些发现为颗粒态和溶解态之间Cd的分配和环境行为提供了有价值的见解，对于理解Cd污染和推进有效的修复策略至关重要。
