Figure 8.

Desalination as a function of energy density and current density for Siltep 11 in (a,b), foamed fireclay in (c,d), and NaCl and Na₂SO₄ as electrolytes. The data show inconsistencies, for instance, the high energy density and low desalination for one case in (a), which was caused by the high voltage that was necessary to sustain the applied current. This may have been caused by temporary scaling inside the porous material or on membranes. The energy required for pumping is not included.