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Facile Postprocessing Alters the Permeability and Selectivity of Microbial Cellulose Ultrafiltration Membranes

Year: 2020

Journal: Environ. Sci. Technol., Volume 54, OCT 20, page 13249–13256

Authors: Holland, Marcus C.; Eggensperger, Christina G.; Giagnorio, Mattia; Schiffman, Jessica D.; Tiraferri, Alberto; Zodrow, Katherine R.

Organizations: Montana Tech Seed Grant; Combat Capabilities Development Command Army Research Laboratory [W911NF-15-2-0020]; NSF EPSCoR CREWS [OIA-1757351]

Water filtration membranes produced sustainably through microbial cellulose production can have filtration properties altered through facile chemical treatments. Microbial cellulose is an effective membrane filtration medium, and pristine microbial membranes can serve as ultrafiltration membranes with a permeability of 143 L m(-2) h(-)(1) bar(-1) and a particle size cut off of 35 nm. As living biofilms, these membranes consist of microbial cellulose, bacteria, and extracellular polymers. Thus, additional biofilm components may reduce the intrinsic permeability of the cellulose. Here, microbial membranes were treated with hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl, liquid bleach) to remove impurities present in microbial cellulose and increase membrane permeability. For example, permeability increased from 143 to 257 L m(-2)h(-1)bar(-1) with treatment by 0.3% H2O2 for 12 min. The membranes were also treated with sodium hydroxide (NaOH) to increase membrane selectivity, and the particle size cutoff was reduced from 35 to 10 nm post-treatment with 0.8% NaOH for 20 min. Scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, contact angle goniometry, and X-ray diffraction were used to characterize the physical and chemical properties of the membrane matrix. Facile chemical treatments provide a significant degree of flexibility to tailor microbial membranes to meet specific needs. Microbial membrane production is inherently accessible, and this study furthers that accessibility by utilizing only readily available components to treat microbial membranes and expand their potential applications.