Insight into the synergy between rice shell biochar particle electrodes and peroxymonosulfate in a three-dimensional electrochemical reactor for norfloxacin degradation

In this study, rice shell biochar (RSB) has been employed as particle electrode in a three-dimensional electro-activation of peroxymonosulfate (3D-PMS) process. According to the experimental results, an outstanding degradation of norfloxacin (NOR) was successfully achieved in the 3D-PMS process. As compared with other processes, the three-dimensional electrode process and PMS oxidation have an obvious synergistic effect. An increase in PMS decomposition was observed due to electrochemical activation and heterogeneous catalysis of RSB. It was found that 87 % of NOR could be degraded in 120 min under optimal conditions of RSB 5 g L−1, NOR 10 mg L−1, PMS 10 mM, and 18 mA cm−2. Some trapping experiments and ESR analyses determine that SO4·-, OH, and 1O2 are all involved in the 3D-PMS process, while 1O2 is dominant ROS for NOR degradation. Furthermore, possible degradation pathways of NOR were investigated and the toxicity of intermediates was analyzed using ecological structure activity relationships (ECOSAR). After RSB was reused for 5 times, Raman spectrum, SEM, BET and FTIR results indicated that surface defects and physical structure were maintained in the 3D-PMS process. Lastly, the practical application of the 3D-PMS process is discussed in detail. Other contaminants, including ATZ, CBZ, SMX, and SMP were also tested in the 3D-PMS process. Based on the above findings, the 3D-PMS process was efficient and sustainable for various pollutants degradation in water.