Method for the operation of electrolytic baths to produce Fe.sub.3 O.sub.4 electrophoretically in a three compartment cell

A method for operation of an electrolytic bath in an electrolytic cell comprising an anode electrode and a cathode electrode opposing the anode electrode;

• said method comprising:
• a. providing two diaphragms arranged between said electrodes;
• said two diaphragms defining an intermediate chamber between said electrodes;
• a first one of said diaphragms and said cathode electrode defining a cathode chamber;
• a second one of said diaphragms and said anode electrode defining an anode chamber;
• b. wherein said first diaphragm is a cation selectively permeable membrane;
• c. circulating different kinds of electrolyte solutions respectively to the anode chamber, the cathode chamber, and the intermediate chamber, characterized in that the cathode chamber solution which is circulatorily supplied into the cathode chamber has a regulator which maintains alkalinity of the cathode chamber solution by decomposing itself in response to electrolysis, said regulator comprising at least one selected from the group consisting of an ammonium salt, a urea carbonate, and a carboxylate;
• d. maintaining the pH of the cathode chamber solution at 8.5 to 10.5;
• e. circulating an electrolyte solution containing a divalent ferrous ion component to said intermediate chamber;
• f. supplying electric current between the anode and the cathode while circulatorily supplying the different kinds of electrolyte solutions respectively into the anode, cathode, and intermediate chambers, causing any divalent ferrous ion component dissolved in the electrolyte solution circulatorily supplied into the intermediate chamber to be selectively electrophoresed toward the cathode;
• g. contacting the divalent ferrous ion with the cathode chamber solution to produce triiron tetroxide (Fe.sub.3 O.sub.4);
• and
• h. separating triiron tetroxide from said cathode chamber solution.