title: Thermodynamics of binding interactions between extracellular polymeric substances and heavy metals by isothermal titration microcalorimetry.
abstract: 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.
authors.affiliation: 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.
authors.forename: Peng
authors.initials: P
authors.lastname: Yan
authors.affiliation: Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China.
authors.forename: Jia-Shuai
authors.initials: JS
authors.lastname: Xia
authors.affiliation: 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. Electronic address: ypchen@cigit.ac.cn.
authors.forename: You-Peng
authors.initials: YP
authors.lastname: Chen
authors.affiliation: Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Liu
authors.affiliation: 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.
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Guo
authors.affiliation: 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.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, China.
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Zhang
authors.affiliation: Chongqing Jianzhu College, Chongqing 400072, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D000818:Animals; D001704:Biopolymers / Q000378:metabolism*; D002151:Calorimetry / Q000379:methods*; D002412:Cations; D002417:Cattle; D004777:Environment; D005110:Extracellular Space / Q000737:chemistry*; D019216:Metals, Heavy / Q000378:metabolism*; D017711:Nonlinear Dynamics; D009994:Osmolar Concentration; D012044:Regression Analysis; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D001704:Biopolymers; D002412:Cations; D019216:Metals, Heavy; D012710:Serum Albumin, Bovine
keywords: Biosorption; Extracellular polymeric substances; Heavy metals; Isothermal titration calorimetry