Kamana Emmanuel

Click mediated high-performance anion exchange membranes with improved water uptake

We acquired herein a novel pendant type anion exchange membrane by grafting brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) with HLTEI (1-(2-(hexylthio)ethyl)-1H-imidazole), a monomer synthesized via click chemistry. The membrane shows improved hydroxide conductivity because of the flexible side chain induced microphase-separated morphology. Low water uptake is the added benefit of the synthesized membrane.

Preparation of pyrrolidinium-based anion-exchange membranes for acid recovery via diffusion dialysis

ABSTRACT In this manuscript, the preparation of pyrrolidinium-based anion-exchange membranes (AEMs) from brominated poly(2,6-dimethyl-1,4-phenyleneoxide) (BPPO) is reported. Prepared membranes were completely characterized in terms of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), ion-exchange capacity (IEC), water uptake (WR), linear expansion ratios (LER), mechanical stability, acid stability, etc. Excellent thermal, mechanical and acid stability can be observed for prepared membranes. Prepared membranes were used in diffusion dialysis (DD) process for acid recovery from model waste HCl/FeCl2 solution. The dialysis coefficient of HCl (UH) is found to be in the range of 0.018–0.049 m/h, whereas the separation factor (S) was obtained as 36.24–66.39. Prepared membranes show much better DD performance than that of commercial fibre–supported DF-120B membrane (0.004 m/h for UH, 24.3 for S at 25°C). Prepared membranes got the potential to be used as a promising candidate for acid recovery via DD.

Preparation and characterization of click-driven N-vinylcarbazole-based anion exchange membranes with improved water uptake for fuel cells

A novel side-chain-type anion exchange membrane (AEM) is synthesized using thiol-ene click chemistry and the Menshutkin reaction. The prepared membranes are fully characterized and successfully mitigate the trade-off between conductivity and water uptake. Side-chain-type polymer electrolyte membranes with moderate hydroxide conductivity and improved water uptake are obtained. The thiol-ene click reaction is employed for the synthesis of active monomer 9-(2-((3-(triethoxysilyl)propyl)thio)ethyl)-9H-carbazole (TESPTEC). Using the Menshutkin reaction, TESPTEC is introduced into the brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) backbone. The NVC-50 membrane shows a maximum hydroxide conductivity of 19.84 ± 1.81 mS cm−1 at 20 °C, and 54.69 ± 2.91 mS cm−1 at 60 °C. However, at 20 °C, the water uptake of the membrane NVC-50 is only about 18.36 wt%. After 12 days of alkaline treatment, the NVC-50 membrane shows better alkaline stability than the conventional QPPO membrane.

Fabrication of cation exchange membrane from polyvinyl alcohol using lignin sulfonic acid: Applications in diffusion dialysis process for alkali recovery

ABSTRACT We report polyvinyl alcohol (PVA)-based hybrid membranes composed of salt of lignin sulfonic acid (LSA) and tetraethyl orthosilicate. The concentration of LSA with respect to PVA varied from 10% to 40%. The hybrid membranes showed water uptake (WU) in the range of 122–210%, ion exchange capacities in the range of 0.32–0.75 mmol g−1, dialysis coefficient (UOH) from 0.0068 to 0.0119 m h−1, and selectivity (S) from 15 to 26. The hybrid membranes also showed thermal and mechanical stability.

Tetrazole tethered polymers for alkaline anion exchange membranes

Poly(2,6-dimethyl-1,4-phenylene oxide) was tethered with a 1,5-disubstituted tetrazole through a quaternary ammonium linkage. The formation of a tetrazole-ion network in the resulting polymers was found to promote the hydroxide ion transport through the Grotthus-type mechanism.