Adsorption characteristics of methylene blue by a dye-degrading and extracellular polymeric substance -producing strain

• Published in: Journal of environmental management Vol. 288; p. 112446
• Main Authors: He, Tao, Hua, Jing-qiu, Chen, Rong-ping, Yu, Lei
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.06.2021
• Subjects: Adsorption; biodegradation; biosorption; cell walls; Coloring Agents; environmental management; Extracellular Polymeric Substance Matrix; Extracellular polymeric substances (EPS); fluorescence emission spectroscopy; Fourier transform infrared spectroscopy; hydrophilicity; Klebsiella oxytoca; Methylene Blue; polymers; Sewage; sludge; Spectroscopy, Fourier Transform Infrared; steam; X-ray photoelectron spectroscopy; Klebsiella oxytoca; Extracellular polymeric substances (EPS); Adsorption; Methylene blue
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2021.112446

Biosorption of dye by microbes and the extracellular polymeric substances (EPS) were of great environmental significance, especially for the dye-degrading and EPS-producing strain. Previous studies were mainly focused on the adsorption capacities and regeneration properties of pure culture, few were on the biosorption of dyes by the dye-degraders and the contributions of EPS on adsorption. In this study, a dye-degrading and EPS-producing strain i.e., Klebsiella oxytoca was used to evaluate its removal capacity to methylene blue. The maximum adsorption capacity (qe) by the strain was calculated as 145 mg g−1, which is superior to many reported bio-adsorbents and some synthetic materials. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results suggested that CO, –NH2 and P-OH groups were involved in the adsorption. High pressure steam sterilization (HPSS) increased the hydrophilicity of cell wall but did not significantly change the cell structure. Compared with the dead resting cell (DRC), the relative higher qe obtained by live resting cell (LRC) possibly due to the loss of some cell structure during the HPSS process. Adsorption experiments by EPS-free LRC, confocal laser microscope and three-dimensional excitation-emission matrix fluorescence spectroscopy results confirmed that the EPS played a role in the adsorption of MB dye. The adsorption characteristics of the dye-degrader and the contributions of EPS on adsorption were investigated in detail in this study. The results were benefit for better understanding of the interaction mechanisms between the dye molecules and cells that before the biodegradation process, which were of great significance for the practical usage of residual sludge on removal of dyes. [Display omitted] •Live cells exhibited a higher adsorption capacity than that by dead cells.•Sterilization increased the cell hydrophilicity but not changed the cell structure.•Electrostatic interaction was the main driving force for methylene blue adsorption.•Fluorescence results confirmed the contribution of EPS on the adsorption.