Congliang Cheng

Effect of novel polysiloxane functionalized poly(AMPS-co-CEA) membranes for base recovery from alkaline waste solutions via diffusion dialysis

In the modern arena of separation science and technology, cation exchange membrane (CEM) based diffusion dialysis (DD) has attracted remarkable attention due to its unique ion transport phenomena during applications for base recovery. In this manuscript, for the first time we reveal novel disodium 4-formylbenzene-1,3-disulfonate modified polysiloxane (FSP) induced poly(AMPS-co-CEA) based CEMs with polyvinyl alcohol (PVA) as a binder and tetraethoxysilane (TEOS) acting as a crosslinker for base recovery via diffusion dialysis. Synthesis of poly(AMPS-co-CEA) involved classical free radical polymerization with azobisisobutyronitrile (AIBN) acting as an initiator. By regulating the dosage of FSP in the membrane matrix, the physiochemical as well as the electrochemical properties of the prepared membranes can be modified. The prepared membranes were investigated comprehensively in terms of water uptake (WR), ion exchange capacity (IEC) along with thermo-mechanical measurements like DMA and TGA. The effect of FSP was discussed in brief to correlate the base recovery behaviour of the prepared membranes. The prepared CEMs have water uptakes (WR) in the range 204.0–248.7%, ion exchange capacities (IEC) between 0.58 and 0.76 mmol g−1, tensile strengths (TS) between 9.3 and 15.9 MPa as well as elongations at break (Eb) of 125.6–236.7%. At 25 °C, the dialysis coefficient (UOH) values appeared as high as 0.0078–0.0112 m h−1 and the separation factors (S) ranged from 10.32 to 14.19. The membranes described in this manuscript could be a promising contender for base recovery via diffusion dialysis.

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.