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Fouling in steady and unsteady state electrodialysis

University of British Columbia

The effects of iron fouling on the steady and unsteady state electrodialysis processes were studied. Both processes were compared on a bench scale, under the same operating conditions of voltage (20 and 30 volts), fluid velocity (1.25 cm/sec), and iron (II) concentration in their feed streams (0, 1, and 5 ppm). A 2000 mg./l. sodium chloride solution containing Fe?? as ferrous chloride was circulated through the process for 20 hours. The amount of deposition on a test pair of membranes was determined and compared to the change in separation factor over the run. The power consumption per litre per cell was determined for both processes and found to be a function of dialysate concentration. Due to limitations in the power supply, the limiting current I lim could not be used as a fouling parameter, and the deposition of iron was measured instead. The separation factor in both processes decreased with the amount of iron accumulated on the membranes, while the polarized cell resistance remained relatively unchanged. This is in agreement with the "sandwich membrane model".

Text

2010-03-29

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http://hdl.handle.net/2429/22832

Chemical and Biological Engineering

University of British Columbia

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