Oxygen-utilization performance of trickle-bed cathode for on-site electrochemical production of hydrogen peroxide

Hydrogen peroxide is one of the most important chemicals used in pulp bleaching because of environmental restrictions on the use of chlorine-based bleaches. An on-site electrochemical production process of hydrogen pet-oxide has been developed for an increasing demand in pulp bleaching. The production cost and operation conditions of the electrolyzer were discussed for the commercially competitive on-site production in this study. The operation cost was estimated from the conditions (the current density, the EDTA dosage, and the oxygen supply ratio) of the electrolyzer. At the condition of the higher electricity unit price the electricity cost was the major factor on the total production cost. Then, the cost minimum point is 1500 A . m(-2) at the higher electricity unit price. At the condition of cheaper electricity unit price the facility cost is affected by the current density. The higher current density (2500 A . m(-2)) is desirable to reduce the initial investment. Then, the trickle-bed cathode's utilization of oxygen was investigated to reduce oxygen supply ratio. The current efficiency is improved at lower oxygen supply ratio by the treatment of fluorocarbon over the carbon fibers (cathode). And thus the current efficiency over 95% is obtained at the oxygen supply ratio of 1.5 times of the stoichiometric requirement at 1500 A . m(-2).