PRODUCTION OF ACIDIC HYDROGEN-PEROXIDE SOLUTION BY CATHODIC OXYGEN REDUCTION .2. WATER TRANSPORTATION AND ELECTROLYTE DIFFUSION THROUGH ION-EXCHANGE MEMBRANES IN ELECTROLYTIC CELL

Water transportation and electrolyte diffusion through ion exchange membranes were investigated in an electrolytic-cell for production of acidic hydrogen peroxide solution. The cell structural components and the configuration were as follows:pure water compartment/an anode plated cation exchange membrane/a H2SO4 solution compartment/an anion exchange membrane/a KOH solution compartment/a gas-diffusion cathode/O2. The water transported through each membrane was experimentally divided into two water flows by osmosis and electro-osmosis. The osmosis through the anion membrane occurred from the H2SO4 compartment to the KOH compartment, indicating negative osmosis, whereas the cation membrane exhibited positive osmosis. The number of water molecule accompanied by an H+, OH-, or HO2- ion was estimated to be about 4, 2 and 10, respectively, from the amount of water by electro-osmosis. As the amount of water through the anion membrane by osmosis was relatively small during electrolysis, eventually, the acidic hydrogen peroxide solution was continuously produced as the overflow from the H2SO4 compartment. The following empirical equation for the amount of overflow(T0/dm3.h-1) was obtained:T0=(4.6+2.9alpha)I+(6.2+3.4alpha)S, where I, S and alpha are current(A), membrane area(dm2) and current efficiency. As for electrolyte diffusion, H2SO4 diffusion through the cation membrane toward the pure water compartment could be ignored during electrolysis, whereas H2SO4 diffusion through the anion membrane toward the KOH compartment was observed even during electrolysis, but the amount was considerably small.