Performance evaluation of diaphragm electrolysis cell for alkali production

Abstract

Seawater desalination technology is important for solving water shortage problems. RO desalination is the most frequently used process for obtaining fresh water from salt water. Electrolysis is also one way of reusing the enriched brine. Alkali-activated products can be made by producing NaOH after electrolysis. There are three kinds of brine electrolysis methods including diaphragm, membrane, and mercury methods. This study was conducted using a 200mL electrolysis diaphragm cell. Tedlar bags were used in order to gather gases such as Cl-2, O-2, and H-2. The head was less than 10mm when a diaphragm with a 10m pore size was used. The data in this study was collected to analyze the relationships between concentration, chloride removal, and current density (CD). Our results showed that pore size influenced the head at the anode. Chloride removal was not high even when a high CD was applied. When the CD was 200mA/cm(2), the maximum NaOH concentration was 1.85%. However, the NaOH concentration was just 1.5% at 100mA/cm(2). The correlation coefficient was also more than 0.99 at a 200mA/cm(2) CD. The applied high CD at the diaphragm cell was unstable because it caused high temperature. The high CD caused the head of the reactor to be higher. Thus, the diaphragm cell could not be operated anymore. The sensitivity analysis results showed that control of the flow rate was more efficient than control of the CD.