Pervaporation of water from aqueous HI using Nafion®-117 membranes for the sulfur–iodine thermochemical water splitting process

Experimental Study for HIx Concentration by Electro-Electrodialysis (EED) Cells in the Water Splitting Sulfur-Iodine Thermochemical Cycle

The efficiency of HI concentration/separation from a HIx solution, (mixture of HI/H2O/I2) represents a crucial factor in the sulfur-iodine thermochemical water splitting process for hydrogen production. In this paper, an experimental study on HI cathodic concentration in HIx solution using stacked electro-electrodialysis (EED) cells was carried out under the conditions of 1 atm and at three different temperature (25, 55 and 85 °C) and using a current density of 0.10 A/cm2. Results showed that an increase in HI concentration can be obtained under certain conditions. The apparent transport number (t+) in all the experiments was very close to 1, and the electro-osmosis coefficient (β) changed in a range of 1.08–1.16. The tests showed a detectable, though slow, increase in both the anodic iodine and cathodic hydriodic acid concentrations.