Method of extracting hexavalent chromium

A method of extracting hexavalent chrome, comprising the steps of:

• immersing a workpiece having a film comprising hexavalent chrome in an electrolyte in a reaction vessel;
• applying a positive and negative voltage to the workpiece,
• performing electrophoresis on hexavalent chrome ions extracted from the film in the electrolyte;
• adding a reducing agent to the reaction vessel before or during electrophoresis;
• contacting the hexavalent chrome ions with the reducing agent, whereby the hexavalent chrome ions are reduced to trivalent chrome ions;
• installing a plurality of ultrasonic wave vibrators on at least one of a bottom and an inner side of the reaction vessel;
• and
• agitating the electrolyte and the reducing agent with the ultrasonic wave vibrators, whereby the extraction and movement of the hexavalent chrome is promoted by shock wave generated when air bubbles are eliminated.