Interactions between metal ions and the biopolymer in activated sludge: quantification and effects of system pH value

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• 作者：Yun Zhou ; Siqing Xia ; Binh T. Nguyen…
• 关键词：Metal ions ; Biopolymer ; Activated sludge ; Three ; dimensional excitation emission ; matrix (3D ; EEM) ; Fluorescence regional integration (FRI) ; technique ; Quantification
• 刊名：Frontiers of Environmental Science & Engineering
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：11
• 期：1
• 全文大小：
• 刊物主题：Environment, general;
• 出版者：Higher Education Press
• ISSN：2095-221X
• 卷排序：11

文摘

The quantification and effects of system pH value on the interactions between Pb(II) and the biopolymer in activated sludge were investigated. The biopolymer had two protein-like fluorescence peaks (Ex/Em = 280 nm/326–338 nm for peak A; Ex/Em = 220–230 nm/324–338 nm for peak B). The fluorescence intensities of peak B were higher than those of peak A. The fluorophores of both peaks could be largely quenched by Pb(II), and the quencher dose for peak B was about half of that for peak A. The modified Stern-Volmer equation well depicted the fluorescence quenching titration. The quenching constant (Ka) values for both peaks decreased with rising system pH value, and then sharply decreased under alkaline conditions. It could be attributed to that the alkaline conditions caused the reduction of available Pb(II) due to the occurrence of Pb(OH)₂ sediments. The Ka values of peak B were bigger than those for peak A at the same system pH values. Accordingly, the aromatic proteins (peak B) played a key role in the interactions between metal ions and the biopolymer.