Evaluation of energy consumption for effective seawater electrolysis based on the electrodes and salinity

This study recommended the effective condition in electrolysis of saline water considering the energy consumption. The experiments were performed using two types of electrodes, IrO2/Ti and Pt/Ti, under various salinity conditions (4, 8, 16, 32, and 46PSU) and current density conditions (11, 33, 55, 111, and 222mA/cm(2)). The electrolysis produced mainly bromine, which was measured as a total residual oxidant (TRO). Seawater electrolysis produced TRO linearly with increasing the run time and current density. Below 32PSU, the electrolysis using the IrO2/Ti electrode produced the TRO greater than that using the Pt/Ti electrode. The TRO formation rate of the IrO2/Ti electrode increased following a half parabola pattern in terms of salinity, while that of the Pt/Ti electrode increased until 32PSU, and then it decreased to 46PSU. The measured electric power of both electrodes showed the same graph tendency with a parabolic curve as a quadratic equation. The energy consumption of the IrO2/Ti and Pt/Ti electrodes showed a quite different tendency. Considering the energy consumption as well as the required time for TRO formation, the same range of current density (30-50mA/cm(2)) is recommended for the two electrodes, IrO2/Ti and Pt/Ti electrodes, even in a different tendency of energy consumption.