PROCESS FOR THE PRODUCTION OF HIGH PURITY AQUEOUS ALKALI HYDROXIDE SOLUTION

摘要

A process for the electrolysis of an aqueous sodium chloride solution in an electrolytic cell comprising an anode compartment and a cathode compartment separated by a cation exchange membrane to obtain an aqueous sodium hydroxide solution having a sodium chloride content of up to 400 ppm in the cathode compartment at high current efficiency by carrying out the electrolysis so that the value of the expression: (wherein F is 96,500 amp sec eq-1; C is the sodium chloride concentration in the anode compartment in eq.cm-3; Co is the sodium chloride limiting concentration in the anode compartment in eq.cm-3; K is the proportionality constant in sec cm-3ohm-1; V is the voltage drop in the membrane; and tNa is the transport number of sodium ions in the membrane) is maintained not higher than 2.74 x 10-4 by controlling the difference of concentration (C - Co) in the range from 0 to 0.001 eq.cm-3.