Spectroscopic study of Zn2+ and Co2+ binding to extracellular polymeric substances (EPS) from aerobic granules.
The interacting mechanisms of metallic cations (Zn2+ and Co2+) to active chemical groups on the extracellular polymeric substances (EPS) of the aerobic granules, including loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS), were examined by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. For Zn2+ and Co2+, LB-EPS showed stronger binding properties than TB-EPS and the process of them was described well by the Langmuir isotherm. Compared to the single-metal system, binary-metal addition induced competitive binding between the Zn2+ and Co2+ with reduction of the maximal binding capacity for both EPS. The main chemical groups involved in the interactions between contaminants were apparently alcohol, carboxyl and amino. These groups were part of the EPS structural polymers, namely, polysaccharides, proteins, and hydrocarbon-like products. When biosorption and flocculation occurred at the same time, the LB-EPS were used not only as chelate sorbents but also as flocculants to further enhance their sorption capacity.
School of Environmental Science and Engineering, Shandong University, Jinan 250100, China. xfsun06@gmail.com
Xue-Fei
XF
Sun
Shu-Guang
SG
Wang
Xiao-Min
XM
Zhang
J Paul
JP
Chen
Xiao-Ming
XM
Li
Bao-Yu
BY
Gao
Yue
Y
Ma