Zeitschrift für Chemieingenieurwesen und Prozesstechnologie
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Optimum Concentrate Stream Concentration in CaCl2 Removal from Sugar Solution Using Electrodialysis

Jogi Ganesh Dattatreya Tadimeti, Anusha Chandra and Sujay Chattopadhyay

Batch electrodialysis (ED) with continuous recirculation was carried out to remove CaCl2 from sugar solution at room temperature. Role of limiting process parameters e.g. (i) concentrate concentration, (ii) sugar mass% cum solution viscosity and (iii) ionic conductivity on electrolyte removal rate were investigated. Unsteady state mass balance defining ion transport through the ED cell with its initial and boundary conditions were solved with linearized Nernst- Planck equation. A new Sherwood number expression appropriate to the cell geometry and process parameters (physical properties and conductivity ratios) is developed as . . . Ë Ë d b c Dil Conc Sh a Re Sc   =     to estimate mass transfer coefficients and ionic flux. Electrolyte removal percentage can’t be correctly estimated from ED cell current instead model based estimates of the flux components due to concentration gradient (chemical potential) and applied electric potential could closely predict the experimental data on electrolyte removal. The ratios of electrolytes removal rates (with and without sugar) can be expressed as power function of viscosity ratios as 0.28 c DSC DSC C percentremoval percentremoval μ μ   =    . This factor of 0.28~0.3 resembles close similarity with Sc number in the Sh number correlation, indicating that the removal rate is a strong function of flow and physical properties of the system. An optimum electrolyte concentration of concentrate, sugar mass% in diluate, and applied electric potential was estimated.