HI extraction by H

M. Lanchi, F. Laria, R. Liberatore, L. Marrelli, S. Sau, A. Spadoni, P. Tarquini

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Iodine excess separation from hydriodic acid (HI) is one of the most challenging steps of the Sulfur-Iodine thermochemical water splitting cycle. One promising method is the extraction of HI by using phosphoric acid (H3PO4), with the subsequent separation of gaseous hydriodic acid from water and H3PO4by a distillation step. The aim of the present work is to provide new experimental liquid-liquid equilibrium data for the biphasic HI/I2/H2O/H3PO4quaternary system, varying both temperature and solution composition in order to optimize the excess of anhydrous phosphoric acid to be added. Two temperature levels were tested, i.e. 100 °C and 120 °C, and the H3PO4amount was varied in the feed mixture from 7.7% wt to 38% wt while the [I2]/[HI] and [H2O]/[HI] molar ratios were kept constant at, respectively, a value of 3.7 and 5.6. A temperature level of 120 °C, with an H3PO4initial concentration of about 29% wt leads to the lowest amount of water against HI, which minimizes energy costs in the phosphoric acid reconcentration step, the most energy consuming part in this separation process. © 2009 International Association for Hydrogen Energy.
Original languageEnglish
Pages (from-to)6120 - 6128
Number of pages9
JournalInternational Journal of Hydrogen Energy
Issue number15
Publication statusPublished - Aug 2009


All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

Cite this

Lanchi, M., Laria, F., Liberatore, R., Marrelli, L., Sau, S., Spadoni, A., & Tarquini, P. (2009). HI extraction by H. International Journal of Hydrogen Energy, 34(15), 6120 - 6128. https://doi.org/10.1016/j.ijhydene.2009.06.010