Stability Prediction of Oxidative Active Species in Electrolytic Sulfuric Acid

By electrolyzing sulfuric acid, two types of oxidative species, peroxymonosulfuric acid and peroxodisulfuric acid, are generated without the addition of hydrogen peroxide. We are developing a technology called “electrolytic sulfuric acid method” to decompose only the resin component of waste carbon fiber reinforced plastics (CFRP) into CO₂ and water using the highly oxidative liquid obtained by electrolyzing sulfuric acid, thereby recycling the carbon fibers. To establish this process, it is necessary to understand the stability of the oxidative species in electrolytic sulfuric acid. However, although detailed studies have been conducted on the generation of oxidative species and their stability immediately after generation through the electrolysis of sulfuric acid, there has been little investigation into their long-term stability suitable for industrial processes. Therefore, in this paper, we conducted experimental investigations on the stability of oxidative species at room temperature and predicted stability using Arrhenius plots at high temperatures. As a result of the investigation, the stability (half-life) of oxidative species generated by the electrolysis of sulfuric acid at 23°C was 224.3 d for peroxymonosulfuric acid and 213.1 d for peroxodisulfuric acid. Thus, it was found that these liquid solutions containing oxidative species can be stored for long periods at room temperature, making them adaptable to industrial processes. The highly oxidative liquid obtained by the electrolysis of sulfuric acid is widely used in the industrial field. Research on the stability of this oxidative power is believed to contribute to the development of these industrial sectors.