Sulfonation Mechanism of Polysulfone in Concentrated Sulfuric Acid for Proton Exchange Membrane Fuel cell Applications

High-performance sulfonated polyether sulfone/chitosan membrane on creatinine transport improved by lithium chloride

Membrane-based polyether sulfone (PES) is a potential candidate for hemodialysis because of its properties such as high mechanical strength, thermal stability, and chemical resistance. However, the nature of the hydrophobicity in the PES membrane inhibits their performance in transporting creatinine. In this study, polyethersulfone (PES) membranes were modified using a sulfonation process and the addition of chitosan (CS) and lithium chloride (LiCl) to improve its performance in transporting creatinine. The FTIR spectrum of the modified membrane shows peaks of the sulfonate (-SO2), amine (NH), and hydroxyl (-OH) groups in absorption areas of 1065 cm-1, 1650 cm-1, and 3384 cm-1, respectively, indicating that the membrane SPES/CS-LiCl has been successfully prepared. The modified PES membranes shows a higher porosity, swelling, water absorption, and hydrophilicity than pure PES membrane. The modification of the PES membrane in this study also enhances the ability of the membrane to transport creatinine. In the pure PES membrane, the creatinine clearance is 0.30 mg/dL, while in the SPES/CS-LiCl (5:2) membrane the creatinine clearance is 0.42 mg/dL.

Sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene/sulfonated poly(ether sulfone) and hexagonal boron nitride electrolyte membrane for fuel cell applications

Novel proton exchange membranes consisting of sulfonated polystyrene ethylene butylene polystyrene (sPSEBPS), sulfonated poly ether sulfone (SPES) and hexagonal boron nitride (hBN) were fabricated using a facile solution casting technique. The PSEBPS polymer was functionalized using chlorosulfonic acid as the sulfonating agent. Polymerization was typically conducted by taking three different monomers, namely 3,6-dihydroxy naphthalene-2,7-disulfonic acid disodium salt, 4,4'-dichlorodiphenyl sulfone, and bisphenol-A, to yield sulfonated poly ether sulfone (SPES). The resultant SPES polymer was blended with sPSEBPS followed by incorporation with an appropriate quantity of hBN. The physicochemical and structural properties of the membranes were studied in order to evaluate their compatibility with fuel cell applications. X-Ray photoelectron spectroscopy data validated the successful incorporation of the filler into the polymer matrix. Water absorption of the membranes was found in the range between 19.5 and 29.8%. The membrane loaded with 4.0 wt% of hBN showed the maximum ion-exchange capacity of 1.21 meq g^-1, whereas the control sPSEBPS/SPES membrane was restricted to 0.48 meq g^-1. The composite membrane loaded with hBN displayed higher thermal stability than that of the control sample. The sPSEBPS/SPES/hBN-4 composite membrane exhibited an ionic conductivity of 0.0329 S cm^-1 at 30 °C. Overall, the experimental data of the prepared composite membranes revealed that the materials are potential candidates for fuel cells.

Proton exchange membrane based on graphene oxide/polysulfone hybrid nano-composite for simultaneous generation of electricity and wastewater treatment

Microbial fuel cell (MFC) is a combined technology for simultaneous generation of electricity and wastewater treatment. In MFC, the proton exchange membrane (PEM) is an essential component affecting electricity generation. In the current study, two proton exchange membranes, namely sulfonated polyethersulfone (SPES) and graphene oxide/sulfonated -polyethersulfone hybrid nanocomposite (GO-SPES), were prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The collected information confirmed the successful preparation of the membranes. Moreover, contact angle measurements, ion exchange capacity and degree of sulfonation of the prepared membranes were determined. The results showed that the introduction of GO nanoparticles into SPES membrane improved its proton exchange capability and resulted in better performance. The power density and the current generated from SPES membrane were 60 mW/m² and 425 mA/m², respectively. For GO-SPES, the obtained power density was 101.2 mW/m² and the current was 613 mA/m². Both membranes showed comparable chemical oxygen demand (COD) removal efficiency of about 80%; suggesting that the prepared membranes are working efficiently in wastewater treatment as PEMs in MFCs. As a final point, the performance of GO-SPES membrane was compared to the performance of the well-known Nafion® 117 membrane and the results were promising. To conclude, the GO-SPES membrane is an outstanding membrane for use as PEM in MFCs for simultaneous generation of electricity and wastewater treatment.

Titanium Dioxide/Phosphorous-Functionalized Cellulose Acetate Nanocomposite Membranes for DMFC Applications: Enhancing Properties and Performance

This study intends to provide new TiO₂/phosphorous-functionalized cellulose acetate (Ph-CA) nanocomposite membranes for direct methanol fuel cells (DMFCs). A series of TiO₂/Ph-CA membranes were fabricated via solution casting technique using a systematic variation of TiO₂ nanoparticle content. Chemical structure, morphological changes, and thermal properties of the as-fabricated nanocomposite membranes were investigated by FTIR, TGA, SEM, and AFM analysis tools. Further, membranes' performance, mechanical properties, water uptake, thermal-oxidative stability, and methanol permeability were also evaluated. The results clarified that the ion-exchange capacity (IEC) of the developed nanocomposite membranes improved and reached a maximum value of 1.13 and 2.01 m_eq/g at 25 and 80 °C, respectively, using TiO₂ loading of 5 wt % compared to 0.6 and 0.81 m_eq/g for pristine Ph-CA membrane at the same temperature. Moreover, the TiO₂/Ph-CA nanocomposite exhibited excellent thermal stability with appreciable mechanical properties (49.9 MPa). The developed membranes displayed a lower methanol permeability of 0.98 × 10^-16 cm² s^-1 compared to 1.14 × 10^-9 cm² s^-1 for Nafion 117. The obtained results suggested that the developed nanocomposite membranes could be potentially applied as promising polyelectrolyte membranes for possible use in DMFCs.