Evaluation of chitosan-derived mixed-matrix membranes as potential separators in bioelectrochemical systems

Bioelectrochemical systems are systems that can use different types of microorganisms, either to purify water and obtain electrical energy through a process of oxidation of organic matter in microbial fuel cells (MFC) or to produce value-added by-products in microbial electrosynthesis cells (MES) such as methane, biohydrogen, bioalcohols and bioplastics. However, within the components of these systems, the proton exchange membranes normally used in these systems are extremely expensive and present certain problems such as fouling or also leakage of gases such as oxygen through the anode and cathode compartments. It is known that chitosan is a derivative of crustacean waste that can be used to form certain membrane coatings to provide improvements to the physicochemical and biological properties of the membrane such as antimicrobial properties.
In the present investigation, modifications were made to commercial ultrafiltration membranes by coating them with chitosan derivatives (Schiff bases) and erbium- and aluminum-doped ZnO photocatalysts, evaluating their antimicrobial, antifouling and biofouling properties, as well as proton and salt exchange capacity by impedance spectroscopy, chemical stability and water holding capacity. The results showed comparable results with commercial Nafion membranes. These results suggest that separators with chitosan-derived biopolymers could be similar candidates to Nafion membranes in bioelectrochemical systems.