Improvement of HI concentration performance for hydrogen production iodine–sulfur process using crosslinked cation-exchange membrane

Cation-exchange membranes (CEMs) were developed using a radiation-grafted polymerization method to improve HI-mediated electro-electrodialysis (EED) in thermochemical water-splitting iodine-sulfur processes. The performance of the HI-mediated reaction was improved using the developed CEMs by introducing divinylbenzene (DVB) as the crosslinker. The effects of the crosslinked CEMs on performance indices such as proton conductivity, transport number, and water permeation factor were investigated. Introducing the crosslinks improved the selectivity of H⁺ and water transport. The permeation mechanism of the proposed EED model was investigated to determine the role of the crosslinkers in this operation. The results indicated that even though the crosslinkers had little effect on the absorption of the HIx solution and the H⁺ diffusion coefficient, a notable decrease was observed in the I⁻ diffusion coefficient. The crosslinkers inhibited swelling caused by the absorption of the HIx solution that led to volume changes known to suppress H₂O permeation.