Evaluation of the formation of oxidants and by-products using Pt/Ti, RuO₂/Ti, and IrO₂/Ti electrodes in the electrochemical process

Abstract

The aim of this study was to evaluate the formation of oxidants and by-products by using different electrode materials, such as Pt/Ti, RuO2/Ti, and IrO2/Ti, in the electrochemical process. The harmful by-products ClO3- and ClO4- were formed during the electrolysis of a Cl- electrolyte solution, as well as active chlorine, which is the most common water disinfectant. With regard to drinking water treatment, the most efficient electrode was defined as that leading to a higher formation of active chlorine and a lower formation of hazardous by-products. Overall, it was found that the Pt/Ti electrode should not be used for drinking water treatment applications, while the IrO2/Ti and RuO2/Ti electrodes are ideal for use.

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

“…With 222 mA/cm 2 of current density, the IrO 2 /Ti electrode generated TRO up to 600 mg/L as Cl 2 , whereas the Pt/Ti electrode generated about the half of TRO (320 mg/L as Cl 2 ) during 10 min of electrolysis. Our comparison of the performance of two electrodes on TRO formation was consistent with previous studies [3,9,17]. In our previous research [9], the IrO 2 /Ti electrode has a high capacity to produce 10 times more chlorine than the Pt/Ti electrode in the same freshwater condition (Cl − = 100 mg/L).…”

“…Our comparison of the performance of two electrodes on TRO formation was consistent with previous studies [3,9,17]. In our previous research [9], the IrO 2 /Ti electrode has a high capacity to produce 10 times more chlorine than the Pt/Ti electrode in the same freshwater condition (Cl − = 100 mg/L). In order to prove the difference between the two electrodes [9], the linear sweep voltammetry (LSV) was performed in the absence and presence of 0.2 M NaCl in the 0.5 M KH 2 PO 4 supporting electrolyte.…”

“…In our previous research [9], the IrO 2 /Ti electrode has a high capacity to produce 10 times more chlorine than the Pt/Ti electrode in the same freshwater condition (Cl − = 100 mg/L). In order to prove the difference between the two electrodes [9], the linear sweep voltammetry (LSV) was performed in the absence and presence of 0.2 M NaCl in the 0.5 M KH 2 PO 4 supporting electrolyte. In the LSV measurement, the difference in the current density between the absence and presence of NaCl indicates oxidizing ability of chloride ion.…”

“…In this study, the formation of active chlorine is a significant factor to inactivate marine organisms for ballast water treatment. In our earlier work [9], an IrO 2 /Ti electrode generated higher concentration of active chlorine and lower concentration of disinfection byproduct (chlorate, ClO À 3 ) than the Pt/Ti electrode, even though the durability of IrO 2 /Ti was wicker than that of Pt/Ti. Therefore, the IrO 2 /Ti and Pt/Ti electrodes that are popular dimensionally stable anode (DSA) for generating oxidants were selected to compare the energy consumption to generate target active oxidants for seawater electrolysis.…”

Suppressed oxygen evolution during chlorate formation from hypochlorite in the presence of chromium(VI)

“…A typical industrial chlorate electrolyte contains 500–650 g dm −3 NaClO 3 , 100–120 g dm −3 NaCl, 3–8 g dm −3 Na 2 Cr 2 O 7 and 1–3 g dm −3 NaClO at T = 70–80 °C and pH = 6–7. An anodic by‐product is perchlorate, which although formed at a low rate on the DSA anodes can build up to high concentrations over some years in the closed‐loop operation . The ionic strength has a significant impact on the hypochlorite decomposition and oxygen formation rate .…”