Bacterial nanocellulose/hydroxyapatite hybrid for proton exchange membrane applied in microbial fuel cells

Fuel cells emerge as a notable opportunity for alternative energy resources, especially microbial fuel cells (MFC), which use microorganisms to biodegrade organic matter to produce electrical energy. However, for this to be economically viable it is necessary to develop cheaper, to increase the efficiency and more environmentally friendly elements. Proton Exchange Membrane (PEM) is one of the main components of MFC. Bacterial nanocellulose (BNC) is produced by bacteria and has attracted large interest for various applications due to its unique nanostructure, biodegradability, and good mechanical properties. Hydroxyapatite (HAp) is a crystalline calcium phosphate and can be synthesized on polymers by different methods, such as biomimetic mineralization. HAp can enhance the proton conductive pathways of membranes. BNC/HAp hybrid membranes were synthesized by a biomimetic mineralization approach and BNC hydrogel as the scaffold. Scanning electron microscopy, X-ray diffraction, Fourier-transformed infrared spectroscopy, and Thermogravimetric Analysis were employed to characterize the pure BNC and BNC/HAp membrane. The porosity of BNC membranes reduced when HAp was synthesized. The BNC/HAp membrane reached a power density of about 31 mW m^-2 within 10 days of MFC operation. The results indicated promising applications of BNC/HAp as a PEM in microbial fuel cells.