ENHANCED IONIC CONDUCTIVITY OF SULFONATED CHITOSAN–SILICA COMPOSITE MEMBRANES DERIVED FROM PALM OIL SHELL WASTE FOR DIRECT METHANOL FUEL CELL APPLICATIONS

The electrolyte membrane, as a proton passage medium, plays an important role in the direct methanol fuel cell (DMFC) system. In this study, an alternative electrolyte membrane was developed through the fabrication of a composite membrane using the biopolymer chitosan and silica filler derived from palm oil shell waste. The membrane synthesis employed the vasa inversion technique with varying amounts of filler (5%, 10%, 15% wt.%) in an acetic acid solution. Initially, a sulfonation treatment with H2SO4 was applied to enhance the functional groups in the membrane structure. Examination of SEM images and FTIR analysis shows the success of combining silica with chitosan biopolymer in the composite membrane structure. The most favorable composite membrane was identified in the Ch/Silica 15 variant, exhibiting water uptake and methanol uptake values of 79% and 57%, respectively. Additionally, the methanol permeability test indicated a value of 0.05 mg.cm².s^-1. The sulfonation treatment contributed to an increased number of functional groups, serving as ion exchange media for membrane performance in fuel cells. The optimal ion exchange capacity was achieved in the Ch/Silica 15 variant with a value of 4.45 mmol.g^-1. Overall, the findings suggest that the composite membrane, consisting of chitosan biopolymer and silica filler, is promising as an electrolyte membrane in DMFC applications.