Liquid electrolytes mixing processes

The use of ILs to replace organic solvents in dye-sensitized solar cells (DSSC) is now well established. Quasi-solid electrolytes with liquid-like mobilities could be prepared by simple mechanical mixing process. This allowed not only an increase of the robustness and stability of the cells but also an improvement of their performance [49,50]. 

The process is one of electrolytic reduction and the apparatus is similar to that shown in Fig. 77, p. 144. It consists of a small porous cell (8 cm. x 2 cm. diam.) surrounded by a narrow beaher (ii cm. X 6 cm. diam.). The oxalic acid, mixed w lth too c.f. 10 per cent sulphuric acid (titrated against standard baryl.a solution] forms the cathode liquid and is placed in Iht beakei. The porous cell is filled with the same strength of siilphuiic acid and foims the anode liquid. The electrodes ara made from 01 dinary clean sheet lead. The anode consists of i thiu strip projecting about two inches from the cell and tliu... 

Siemes and Weiss (SI4) investigated axial mixing of the liquid phase in a two-phase bubble-column with no net liquid flow. Column diameter was 42 mm and the height of the liquid layer 1400 mm at zero gas flow. Water and air were the fluid media. The experiments were carried out by the injection of a pulse of electrolyte solution at one position in the bed and measurement of the concentration as a function of time at another position. The mixing phenomenon was treated mathematically as a diffusion process. Diffusion coefficients increased markedly with increasing gas velocity, from about 2 cm2/sec at a superficial gas velocity of 1 cm/sec to from 30 to 70 cm2/sec at a velocity of 7 cm/sec. The diffusion coefficient also varied with bubble size, and thus, because of coalescence, with distance from the gas distributor. 

Reactive absorption processes occur mostly in aqueous systems, with both molecular and electrolyte species. These systems demonstrate substantially non-ideal behavior. The electrolyte components represent reaction products of absorbed gases or dissociation products of dissolved salts. There are two basic models applied for the description of electrolyte-containing mixtures, namely the Electrolyte NRTL model and the Pitzer model. The Electrolyte NRTL model [37-39] is able to estimate the activity coefficients for both ionic and molecular species in aqueous and mixed solvent electrolyte systems based on the binary pair parameters. The model reduces to the well-known NRTL model when electrolyte concentrations in the liquid phase approach zero [40]. 

---