Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Science, Chongqing 400714, China.
Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China.
Bioresour Technol. 2017 May;232:354-363. doi: 10.1016/j.biortech.2017.02.067. Epub 2017 Feb 20.
Extracellular polymeric substances (EPS) play a crucial role in heavy metal bio-adsorption using activated sludge, but the interaction mechanism between heavy metals and EPS remains unclear. Isothermal titration calorimetry was employed to illuminate the mechanism in this study. The results indicate that binding between heavy metals and EPS is spontaneous and driven mainly by enthalpy change. Extracellular proteins in EPS are major participants in the binding process. Environmental conditions have significant impact on the adsorption performance. Divalent and trivalent cations severely impeded the binding of heavy metal ions to EPS. Electrostatic interaction mainly attributed to competition between divalent cations and heavy metal ions; trivalent cations directly competed with heavy metal ions for EPS binding sites. Trivalent cations were more competitive than divalent cations for heavy metal ion binding because they formed complexing bonds. This study facilitates a better understanding about the interaction between heavy metals and EPS in wastewater treatment.
胞外聚合物（EPS）在利用活性污泥进行重金属生物吸附中起着至关重要的作用，但重金属与 EPS 之间的相互作用机制尚不清楚。本研究采用等温热力学滴定法来阐明这一机制。结果表明，重金属与 EPS 之间的结合是自发的，主要由焓变驱动。EPS 中的胞外蛋白质是结合过程中的主要参与者。环境条件对吸附性能有显著影响。二价和三价阳离子严重阻碍了重金属离子与 EPS 的结合。静电相互作用主要归因于二价阳离子与重金属离子之间的竞争；三价阳离子直接与重金属离子竞争 EPS 结合位点。由于形成了配位键，三价阳离子比二价阳离子更具竞争力，从而与重金属离子竞争结合位点。本研究有助于更好地理解废水处理中重金属与 EPS 之间的相互作用。
