| 摘要 |
A process for electrolyzing an aqueous catholyte solution comprising an alkali meal bisulfite to produce an alkali metal hydrosulfite in an electrolytic membrane cell having a cation exchange membrane separating a cathode compartment from an anode compartment, a porous cathode having a face adjacent the membrane, a back opposite, and a porous structure conjoining the face and the back, and a cathode-membrane gap between the porous cathode and the cation exchange membrane. The process comprises directing at least 50 percent of the volume of the aqueous alkali metal bisulfite catholyte through the porous cathode and transverse to the face and back of the cathode, the porous cathode having a ratio of total surface area to the projected surface area of at least about 30:1. High purity solutions of alkali metal hydrosulfites, such as sodium hydrosulfite having concentrations of at least 120 grams per liter, are produced at current densities in the range of 1.0 to 4.5 KA/m2 and at reduced cell voltages. The thiosulfate impurity concentration is from 0 to about 10 percent by weight of the hydrosulfite.
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