Application of modified chitosan membrane for microbial fuel cell: Roles of proton carrier site and positive charge

Abstract

Modified chitosan membrane was synthesized as a proton exchange membrane for microbial fuel cell application. Glutaraldehyde and sulfosuccinic acid were used as crosslinking agents in order to improve its ultimate tensile strength and proton conductivity. 3-Chloro-2-hydroxypropyl trimethylammonium chloride was employed for quaternization to develop its antimicrobial activity. The results showed that the proton conductivity of the membrane was enhanced with the content of sulfosuccinic acid, as a result of proton carrier sites, until a certain value was reached. The additional positive charge from quaternization increased with the reaction time. The morphological change of microorganisms in contact with the surface of the quaternized chitosan membrane exhibited damage and the number of damaged microorganisms increased with the positive charge density; nevertheless, the high positive charge density resulted in not only a high antimicrobial property, but also in significant water uptake of the quaternized chitosan membrane. As a consequence, the strength of the membrane was lost. Additionally, the positive charge also accelerated the adhesion of microorganisms at the membrane surface, but the surface growth could be retarded due to the high number of microorganisms being damaged.