Effect of Red Tide on Limiting Current Density

The sorption effects of the red tide and its contents on the ion exchange membranes have been investigated under various electrodialysis conditions. Aqueous NaCl solution suspended with the contents of the Chattonella antiqua, which is a typical phytoplankton species of the red tide, was passed through the desalting chamber in an electrodialysis apparatus. The effects of current densities and the contents of the Chattonella antiqua on electrodialysis were examined. pH change of the effluent and limiting current density in the desalting chamber were measured, and sorped species on the ion exchange membranes were analyzed. It was found that sorped species on the anion exchange membrane were mainly chlorophyll α-protein complexes and pheophytin α-protein complexes remarkably influenced the limiting current density; i. e., a pronounced decrease in the limiting current density occurred in the presence of the complexes. The contribution of Chattonella antiqua to the limiting current density of the cation exchange membrane was found to be very small during the electrodialysis. The sorption of Chattonella antiqua contents on the cation exchange membrane was almost undetectable.