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Novel Pendant Benzene Disulfonic Acid Blended SPPO Membranes for Alkali Recovery: Fabrication and Properties

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journal contribution
posted on 29.07.2015 by Abhishek N. Mondal, Chunhua Dai, Jiefeng Pan, Chunlei Zheng, Md. Masem Hossain, Muhammad Imran Khan, Liang Wu, Tongwen Xu
To reconcile the trade-off between separation performance and availability of desired material for cation exchange membranes (CEMs), we designed and successfully prepared a novel sulfonated aromatic backbone-based cation exchange precursor named sodium 4,4′-(((((3,3′-disulfo-[1,1′-biphenyl]-4,4′-diyl)­bis­(oxy)) bis­(4,1-phenylene))­bis­(azanediyl))­bis­(methylene))­bis­(benzene-1,3-disulfonate) [DSBPB] from 4,4′-bis­(4-aminophenoxy)-[1,1′-biphenyl]-3,3′-disulfonic acid [BAPBDS] by a three-step procedure that included sulfonation, Michael condensation followed by reduction. Prepared DSBPB was used to blend with sulfonated poly­(2,6-dimethyl-1,4-phenylene oxide) (SPPO) to get CEMs for alkali recovery via diffusion dialysis. Physiochemical properties and electrochemical performance of prepared membranes can be tuned by varying the dosage of DSBPB. All the thermo-mechanical properties like DMA and TGA were investigated along with water uptake (WR), ion exchange capacity (IEC), dimensional stability, etc. The effect of DSBPB was discussed in brief in connection with alkali recovery and ion conducting channels. The SPPO/DSBPB membranes possess both high water uptake as well as ion exchange capacity with high thermo-mechanical stability. At 25 °C the dialysis coefficients (UOH) appeared to be in the range of 0.0048–0.00814 m/h, whereas the separation factor (S) ranged from 12.61 to 36.88 when the membranes were tested for base recovery in Na2WO4/NaOH waste solution. Prepared membranes showed much improved DD performances compared to traditional SPPO membrane and possess the potentiality to be a promising candidate for alkali recovery via diffusion dialysis.

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