Studies on the preparation of Caro’s acid by ultrasonic enhanced electrochemistry

Abstract

Abstract. Ultrasonic cavitation effects can generate hydroxyl radicals and high energy, which is widely applied in the field of oxidation currently. Ultrasound-enhanced electrochemical is used to prepare Caro's acid, which improves the generate rate of Caro's acid. In this article, the influences of ultrasonic frequency and ultrasonic power on the electrolysis voltage, electrolyte temperature, electrolyte concentration and the concentration of additive in the process of electrochemical preparation of Caro's acid was studied. And the optimal production conditions were determined. The research results showed that ultrasonic can significantly improve the production of Caro's acid and the product can increase by about 20 g/L under the best condition. IntroductionThe study on ultrasonic-induced electrochemical reactions has developed rapidly, which was widely used in water treatment [1-2], ore decomposition [3], electroplating [4] and preparation of nanomaterials [5][6][7][8] and other fields currently. Zhuping [9] and her co-workers had studied treatment of nonleaching refractory gold ores with electrochemical antioxidant under two conditions including ultrasonic and ultrasonic condition. The results showed that ultrasound can reduce the reaction time and increase leaching rate by 35.84%.Electrolytic oxidation technology [10][11], which is a green and efficient chemical process, is widely used in wastewater treatment [12].with the aid of ultrasonic; the electrochemical process can enhance the mass transfer process, reduce the electrolytic voltage and reduce the energy consumption in ultrasonic environment. Moreover, ultrasonic cavitation can produce a micro environment of high temperature and high pressure, which can produce a lot of hydroxyl radicals with high oxidizing ability and improve oxidation efficiency. Domestic and foreign scholars mainly applied ultrasonic electrochemical oxidation to wastewater treatment. For example, Zhao Guohua [13] from Tongji University combined boron doped electrode with ultrasound to treat phenol and phthalic acid. The results showed that hydroxyl radical produced during electrolytic process under ultrasonic environment. Furthermore, the oxidation capacity increased and the oxidation peak increased by 32%, the degradation efficiency was significantly improved. Meanwhile the energy consumption was greatly reduced.In this study, ultrasonic chemical and electrochemical were combined together for the preparation of Caro's acid in a low concentration of sulfuric acid. The results indicated that the anode oxidation rate, current efficiency and mass transfer rate were improved greatly with a reduced energy consumption.