title: Preparation of dual-function starch-based flocculants for the simultaneous removal of turbidity and inhibition of Escherichia coli in water.
abstract: A dual-function starch-based flocculant, carboxymethyl-starch-graft-aminomethylated-polyacrylamide (CMS-g-APAM), was designed and prepared by a simple method. The structure and solution properties of CMS-g-APAM were characterized by fourier transform infrared spectroscopy, (1)H nuclear magnetic resonance, and zeta-potential measurements. CMS-g-APAM was then applied to flocculate a kaolin suspension and an Escherichia coli suspension as well as a combination thereof. At suitable pH conditions, the starch-based flocculant not only effectively removed turbidity but it also disrupted bacterial cells. Interpretation of the zeta potential and floc properties (floc size and two-dimensional fractal structure) showed that, for the aforementioned three effluents, simple charge neutralization was the dominant mechanism of flocculation in acidic medium whereas an additional contribution from a patching effect was determined under neutral conditions. Three-dimensional excitation-emission matrix spectra and direct surface morphology observation under a scanning electron microscope both illuminated that the antibacterial activity of CMS-g-APAM involved the partial destruction of the cell wall of Escherichia coli. The mechanism can be attributed to the effective interaction between the tertiary amine group of the flocculant and the negatively charged surface of the bacterium.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Mu
authors.initials: M
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Yawen
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Bai
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China. Electronic address: yanghu@nju.edu.cn.
authors.forename: Hu
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
mesh_terms: D004926:Escherichia coli; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D013213:Starch / Q000737:chemistry; D014867:Water
chemical_list: D014867:Water; D013213:Starch
keywords: Dual-functionality; Flocculation and antibacterial mechanisms; Inhibition of Escherichia coli; Starch-based flocculants; Turbidity removal