Analytical Sciences

In-line System to Produce High-Purity Acid Solutions

Hiroto MASUNAGA,* Yuji HIGO,* Mizuo ISHII,* Noboru MARUYAMA,* and Shigeo YAMAZAKI**

*Nichiri Mfg. Co., Ltd., 324-5 Takatsu, Yachiyo, Chiba 276-0036, Japan
**Department of Applied Science, Okayama University of Science, 1-1 Ridaicho, Okayama 700-0005, Japan

Herein, we report a new device that generates a high-purity acid solution. It comprises three compartments divided by anion-exchange membranes and filled with ion-exchange resins. Fluorochemical cation-exchange membranes, which tolerate electrochemical wear and permit bulk flow, are inserted between each electrode and the anion-exchange resin. A bipolar boundary is a composite boundary comprising anion and cation exchangers. This device has four bipolar boundaries to separate the location of acid generation from the location where water is electrolyzed. It can tolerate high pressures, resist degradation due to electrolysis at the electrodes, and produce high-purity acid solutions that are free from gases and cationic impurities. The acid solution is generated on the basis of an electrokinetic phenomenon at the surfaces of ion-exchange resins and membranes in an electric field; its concentration can be controlled at rates from 0.01 to 100 μmol/min by adjusting the electrical current applied to the device.

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