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Enhancement mechanisms of copper(II) adsorption onto kaolinite by extracellular polymeric substances of Microcystis aeruginosa (cyanobacterium)

Author:
Kuang, Xiaolin, Peng, Liang, Chen, Anwei, Zeng, Qingru, Luo, Si, Shao, Jihai
Source:
International biodeterioration & biodegradation 2019 v.138 pp. 8-14
ISSN:
0964-8305
Subject:
Fourier transform infrared spectroscopy, Microcystis aeruginosa, adsorption, clay, copper, eutrophication, kaolinite, kinetics, moieties, sorption isotherms, surface water, titration
Abstract:
Microcystis aeruginosa frequently forms cyanobacterial blooms in eutrophic water bodies, resulting in high concentrations of extracellular polymeric substances (EPS) in the water column. The effects of M. aeruginosa EPS (MA-EPS) on the adsorption behavior of Cu(II) onto kaolinite and the possible mechanisms were investigated in this study. The results of potentiometric titration and Fourier transform infrared (FT-IR) spectroscopy determination show that carboxyl, phosphoryl and amino/hydroxyl groups were the main adsorption groups on MA-EPS. The combination of EPS with kaolinite created new adsorption sites. MA-EPS increased the adsorption of Cu(II) by kaolinite mainly through complexation. The adsorption kinetics of Cu(II) by kaolinite or kaolinite + EPS composite (Kao + EPS) was well fitted by a pseudo-second order kinetic model. The adsorption isotherm analyses show that the incorporation of MA-EPS onto kaolinite increased its surface heterogeneity. Rather than intercalating into the kaolinite interlayers, MA-EPS and/or Cu(II) were adsorbed onto the surface of this clay.
Agid:
6266003