Development of Sustainable Biopolymer Proton Exchange Membranes for Energy Production in Microbial Fuel Cell Technology

• Main Authors: SHIMA LATOYA HOLDER, 希瑪
• Other Authors: CHING-HWA LEE
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/usmw7a

博士 === 大葉大學 === 環境工程學系碩士班 === 105 === Improving energy recovery from wastewater is a sustainable approach for wastewater treatment and can be of much interest toward protection and improvement of the water environment. Microbial fuel cell (MFC) technology provides a direct approach to energy production from wastewater streams and is of much interest at the interface of Chemical and Environmental Engineering, Electrical Engineering and Materials Science. Besides its ability for bioelectrical power generation, simultaneous wastewater treatment can be achieved thereby expanding its scopes for application. Albeit MFC technology is promising, a number of hurdles need to be overcome before it can be considered economically and environmentally feasible. Proton exchange membranes (PEMs) are a central component in MFC technology due to the importance of proton transport in facilitating the redox reaction occurring in MFC systems. The development of low cost, environmentally friendly and sustainable PEM materials is still an attractive research area for membrane-based fuel cell technology. This study explored the modification of natural, abundant, low-cost, non-toxic and eco-friendly chitosan (CS) biopolymer toward its application as a viable proton exchange material in MFC systems by blending and crosslinking methods. CS was blended with sorbitol and sodium alginate, and filled with graphene oxide to form CS-based plasticized, polyelectrolyte and mixed-matrix proton exchange membranes (PEMs) respectively, and crosslinked with phosphoric and sulfuric acid groups. Extensive physicochemical, thermal and mechanical characterization of the synthesized CS-based PEMs through FESEM-EDS, FTIR-ATR, XRD, TGA, tensile strength, cation exchange capacity and sorption studies indicated that blending solutions and crosslinking agents potentially influenced the physicochemical properties suitable for improved fuel cell performance of CS in terms of bioelectricity production and wastewater treatment. Modification prior to membrane formation proved effective for reducing membrane stress of the rigid CS structure, increasing polymer chain flexibility and promoting interfacial formations. Interrogation of the crosslinked CS-based PEMs demonstrated that ionic crosslinking based on the incorporation of PO43- groups in the CS matrix, when compared with sulfuric acid crosslinking commonly used in MFC studies, generated additional density of ionic cluster domains, rendered enhanced membrane sorption behaviour and augmented the thermal and mechanical stability of the PEM structure. Consequently, maximum power density of pristine unmodified chitosan improved from 32.96 mW/m3 to 257, 349.22 and 451.35 mW/m3 using the modified CS-based PEM synthesized by crosslinking with phosphoric acid for 24 h (CS-P(24)), filled with graphene oxide CS-GO(5)-P(24) and blended with alginate CS-Alg(1:1)-P(24) respectively; furthermore, a maximum of 89.52% COD removal of primary clarifier municipal wastewater was achieved in the MFC operated with the mixed-matrix crosslinked CS-GO-P(24) membrane. The MFCs operated with modified CS-based PEMs exhibited enhanced performance. Thus, through modifications, the physicochemical and mechanical properties of natural abundant biopolymer chitosan can be enhanced for its use as an environmentally sustainable PEM in MFC technology.