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Adsorption behavior of tightly bound extracellular polymeric substances on model organic surfaces under different pH and cations with surface plasmon resonance

Zhang, Peng, Chen, You-Peng, Guo, Jin-Song, Shen, Yu, Yang, Ji-Xiang, Fang, Fang, Li, Chun, Gao, Xu, Wang, Gui-Xue
Water research 2014 v.57 pp. 31-39
adsorption, bioreactors, cations, iron, pH, sodium, surface plasmon resonance
Tightly bound extracellular polymeric substances (TB-EPS) play a substantial role on microbial aggregates, which can promote microbial cells to aggregate and adhere onto the carrier in bioreactor. However, the attachment and adsorption of TB-EPS on different surfaces were awaited to be elucidated. In this study, four self-assembled monolayers (SAMs) carrying methyl (CH3-SAM), amino (NH2-SAM), hydroxyl (OH-SAM), and carboxyl (COOH-SAM) terminal groups were prepared to model different surfaces. TB-EPS adsorption on these surfaces under different pH conditions and additional cations were investigated using surface plasmon resonance. The adsorption of TB-EPS dramatically decreased with the decreasing pH values. CH3-SAM surface achieved the maximum adsorption at the same condition. Na+ promoted the TB-EPS adsorbed on COOH-SAM surface. The Ca2+-mediated complexes were attracted by COOH-SAM and repelled by NH2-SAM, respectively. The adsorptions of TB-EPS on the four SAM surfaces were significantly increased by adding Fe3+. These results demonstrated that the TB-EPS adsorption on the organic surfaces were dependent on the pH and cation of solution.