Metal-organic frameworks (MOFs) are widely explored for the advancement in hybrid membranes because of their bonding and fondness in polymers. Particularly, hybrid polymeric ultrafiltration (UF) membranes are fabricated using engineered...
Custom-made nanocomposite proton exchange membranes (PEMs) are fabricated using the blends of sulfonated chitosan (S-Chitosan) and sulfonated graphene oxide (SGO) nanosheets for direct methanol fuel cells (DMFCs). Sulfonation of chitosan and GO are carried out by 1,3-propane sultone and sulfanilic acid, respectively. Scanning electron microscope (SEM) with energy dispersive X-ray investigation revealed that the thick, folded and wrinkled sheet-like morphology of SGO and the existence of elemental sulfur. SEM and atomic force microscopy images showed the uniform dispersion of hydrophilic SGO nanosheets. Besides the S-Chitosan/SGO membranes showed higher water uptake, swelling ratio and ion exchange capacity due to the enhancement in hydrophilicity. The modified PEMs displayed improvement in proton conductivity since the ion-exchangeable sulfonic acid groups facilitate the proton conduction and effectively resist the methanol permeability by forming a strong hydrogen bond network with chitosan and thus diminish the void volume. Particularly, S-Chiotsan-1 membrane showed superior proton conductivity of 4.86 Â 10 À3 Scm À1 at (25 C), selectivity of 1.89 Â 10 5 Scm À3 s and lesser methanol permeability of 2.57 Â 10 À8 cm 2 s À1 . Overall results suggest that the S-Chitosan/ SGO membranes found to be a suitable alternate for Nafion ® in DMFCs.
This study deals with the making of poly(vinylidene fluoride) (PVDF) hybrid ultrafiltration (UF) membranes incorporated with zeolitic imidazolate framework-8 (ZIF-8) nanocrystals. The surface morphology and roughness of ZIF-8 are explored in terms of atomic force microscopy (AFM) and scanning electron microscopy (SEM) whereas their distribution in PVDF matrix and antibacterial activity are probed by energy dispersive X-ray (EDX) analysis and zone of inhibition test. The chemical functionality of ZIF-8 is verified by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopic studies. The permeability of hybrid membranes is raised to 2 wt% addition of ZIF-8 into the PVDF matrix owing to an enhancement in hydrophilicity and porosity. The FESEM images of the top and cross-section view make visible the formation of macrovoids with the addition of ZIF-8. On account of high porosity and surface hydrophilicity, the pure water permeation of hybrid membranes is increased to 278.6 Lm À2 h À1 . The hybrid membranes showed higher rejection and permeate flux of bovine serum albumin (BSA; 92.8 Lm À2 h À1 ) and humic acid (HA; 94.3 Lm À2 h À1 ) owing to the synergetic effect of their enhanced hydrophilicity and surface roughness. This is confirmed by the higher flux recovery ratio (FRR) and lower irreversible fouling characteristics of hybrid PVDF membranes. The atomic absorption spectroscopy (AAS) revealed the long-standing stability of ZIF-8 in the PVDF matrix. Among all, the PVDF hybrid membrane with 2 wt% of ZIF-8 showed excellent permeability, antifouling, and antibiofouling ability and was found to be more effective in water treatment applications.
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