Advances in Dye Removal Technologies by Sourav Mondal Mihir Kumar Purkait & Sirshendu De

Author:Sourav Mondal, Mihir Kumar Purkait & Sirshendu De
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

(5.71)

where and ; u 0 is the cross-sectional average velocity in the channel; and ρ , μ , D are the solution density, viscosity, and the solute diffusivity, respectively.

5.2 Experiments in Unstirred Batch Cell

5.2.1 Single Component System

Figure 5.1 shows the variation of permeate flux with time for different feed concentrations of crystal violet at different pressures. It is evident from the figure that the permeate flux decreases with time of operation. This is due to the concentration polarization phenomenon. During the experimental run, the membrane surface concentration increases. This leads to an increase in the osmotic pressure near the membrane-solution interface and, thereby, a decrease in the available driving force (i.e., transmembrane pressure) resulting in a reduction in permeate flux. It may be observed from the figure that the decline in flux at the end of the operation is about 15% from its initial value for the feed concentration of 19.87 mg/l and 550 kPa pressure. At higher feed concentration, the solute buildup on the membrane surface is more, resulting in larger reduction in the permeate flux. On the other hand, for a fixed feed concentration of 19.87 mg/l, the increase in flux with operating pressures 415, 550 and 690 kPa is evident in the figure. It can also be observed that at a fixed pressure (550 kPa), permeate flux decreases with the feed concentration (hollow circle, square, and the cross symbols).

Fig. 5.1Variation of permeate flux of crystal violet with time at different feed concentrations and operating pressure differences in the batch cell (the solid lines are guides for the reader’s eyes) (Reproduced from Chakraborty et al. (2003b) with permission from Taylor & Francis Ltd)

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