Decolorization of China clay by electrolytic reduction

When a direct current flows through an agitated suspension of China clay in acidic reducing agent solution, iron compounds are reduced to soluble compounds. Consequently, colored China clay is decolored by electrolytic reduction. If sulfurous acid water was used as reducing agent, a large quantity of sulfurous gas was produced during the operation. Then the author attempted to use ammonia water, to prevent gas productions. The experimental results were as follows : … 1. Decolorization of China clay was performed only in the acidic solution. 2. The upper limit of acidic suspension pH was about 5.5 3. By using a diaphragm, China clay was decolord in the acidic catholyte opposite to the basic anolyte