Photocatalytic technology represents a green and environmentally friendly technology, whose development, however, is hindered by problems such as easy recombination of photoelectrons and holes, short life span of active free radicals, and slow reaction rate. Fortunately, persulfate-assisted photocatalytic technology has attracted widespread attention during the last few years. Persulfate (PS) can be served as an electron acceptor to promote charge transfer of the photocatalytic reaction owing to its oxidation capability for the immediate trapping of photo-generated electrons. And the key factors of persulfate-assisted photocatalytic technology lie in the design of photocatalyst.
Thanks to the efforts of the Pollutant Environmental Behavior and Pollution Control Team from the School of Environment at Nanjing Normal University, a novel Co3O4/g-C3N4/Bi2O2CO3 (BCCN) photocatalyst with p-n/n-n heterojunction was synthesized through a solvent-thermal method. The degradation efficiency of 20 mg/L iohexol reached 94 % in 60 min (kapp =0.0417 min−1) in BCCN/light/PS system, which was 2.8 and 6.5 times higher than systems of BCCN/light (kapp =0.0150 min−1) and BCCN/PS (kapp =0.0064 min−1). The g-C3N4 addition lowered conduction band of the prepared material to produce superoxide radicals, activate persulfate and further prevent the recombination of photoelectrons and holes. Superoxide radicals and singlet oxygens were dominant radicals for iohexol degradation. Besides, persulfate could act as electron acceptor to enhance efficiency of electron transfer. The interaction between sulfate, superoxide and hydroxyl radicals improved singlet oxygens production. Furthermore, theoretical calculation and liquid chromatography mass spectrometry were performed to analyze degradation pathway of iohexol in the system. Ultimately, the BCCN/light/PS system can provide a new method to degrade organic pollutants in aquatic environments.
Recently the above results were published in Applied Catalysis B: Environmental. Weiming Xiang, a master’s degree candidate enrolled in the School of Environment in 2018, is the first author of the paper, and Professor Shaogui Yang and Professor Huan He are the corresponding authors. This work was supported by the Jiangsu Provincial Key Research and Development Program, the Six Talent Peaks Project in Jiangsu Province, the National Nature Science Foundation of China, Major Science and Technology Program for Water Pollution Control and Treatment.