Decolorization of rhodamine B using an ultrasonic oxygen-doped carbon felt as cathode in electro-Fenton system

The inertness of carbon felt as cathode is still one of the challenges encountered in the degradation of pollutants by electro-Fenton. In this study, we used a simple ultrasonic oxidation method to introduce oxygen-containing groups and defect carbons on carbon felt surface to improve the electro-Fenton performance. The modified carbon felts were prepared by ultrasonic treatment in three dilute solutions of HNO 3 , H 2 SO 4 , and HNO 3 –H 2 SO 4 . Ultrasound can provide an extra energetic environment to accelerate the oxidation process, while NO 3 − has stronger oxidation properties in the presence of excess H + , greatly increasing the amounts of C–O–C/C=O and C–C active sites on carbon felt surface. And an electro-Fenton system with modified CF as the cathode was used to degrade rhodamine B, and the factors affecting the degradation were discussed. The results showed that the modified cathode material was significantly more efficient in degrading rhodamine B, under the conditions of O 2 flow rate of 0.3 L min −1 , pH = 3, voltage of − 0.7 V, and addition of 0.2-mM Fe 2+ , HNO 3 –H 2 SO 4 solution modified CF with 37% higher than that of the raw CF, and the decolorization rate reached 96% after 120 min. Modified carbon felt still has good degradation properties after 5 cycles. Graphical abstract The CF was modified by ultrasonic oxidation technique to introduce oxygen-containing functional groups and C-sp3 on the surface of the carbon felt.Using this CF as a cathode for the degradation of RhB in an electro-Fenton system.