The Effect of Phosphotungstic Acid Filled on Carboxymethyl Cellulose/Polyvinyl Alcohol Matrix as the Polymer Electrolyte Membrane

Abstract

In this work, the researchers developed a new composite membrane based on Polyvinyl Alcohol (PVA) doped carboxymethyl cellulose (CMC) matrix to obtain mixed matrix membranes (MMMs) that showed a high methanol resistance and also applied the citric acid (CA) as a crosslinking agent. The addition of Phosphotungstic Acid (PTA) as filler into the CMC/PVA matrix aims to improve the performance of the membranes. The composite membranes were evaluated for chemical stability, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infra-red (FTIR), water uptake (WU), methanol uptake (MU), methanol permeability, and ion exchange capacity (IEC). The results showed the prominent value of oxidation stability according to its weight loss of 49.81 to 7.39% at 50 °C, the WU in the range of ± to 71.34%, the IEC of 0.17 to 0.72 mmol/g, the MU in the range 31.96 % to 4.38% and permeability of methanol in the range 17.28 × 10 -7 to 2.27 × 10 -7 cm 2 /s. The methanol permeability and uptake decreased along with the increase of the amount of PTA in the composite membrane. The addition of PTA increased the IEC and demonstrated significant positive effects in the composite membranes. In conclusion, the CMC/PVA/PTA membrane can be recommended as promising biomaterial for polymer electrolyte membrane direct methanol fuel cell (DMFC) applications.