HI Concentration fromHIx (HI-H2O-I2) Solution for the ThermochemicalWater-Splitting IS Process by Electro- Electrodialysis

Electro-electrodialysis (EED) was carried out for the HI concentration from HIx (HI-H2O-I2) solution to improve the HI decomposition reaction in the thermochemical water splitting IS (Iodine-Sulfur) process. The EED cell is composed of the collector, electrode, and electrolyte. Nafion 117, which is a cation exchange membrane, was used as an electrolyte; an activated carbon cloth was used as an electrode. The HI concentration experiment was performed using the HIx solution (molar ratio of HI H2O: I2 =1 5 0.5) and temperatures in the region 30 120 o C. The electro-osmosis coefficient and proton transport number were 1.069 1.385 (mol/Faraday) and 0.739 0.875, respectively. The experimental data showed that the quasi- azeotrope composition was broken in all experimental cases. From the experimental results, it is expected that the EED process will be useful for improving the HI decomposition reaction in the IS process.