Huang Shaoyong,Huang Quanjia,Gan Jiaming,Li Ting,Wang Lei
In this study, Fe-rich sludge was pretreated by dielectric barrier discharge (DBD) and used as a Fenton catalyst for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution, where hydrogen peroxide was in situ supplied from a glow discharge plasma (GDP) in contact with the solution. Synergistic mechanism of the two plasmas during 2,4-D degradation was explored. The Fe-rich sludge pretreated by H 2 -DBD could significantly accelerate the 2,4-D degradation as it converted Fe(III) in the sludge to the active Fe(II). 2,4-D can be completely removed in the presence of H 2 -DBD pretreated Fe-rich sludge with 25 min of GDP at pH 0 3.0 and catalyst dosage of 1.0 g/L. Quenching experimental studies showed that both ·OH (oxidative degradation) and ·H (reductive dechlorination) were responsible for 2,4-D degradation. Reducing radicals (such as ·R and·H) formed during GDP can continuously reduce the Fe 3+ back to Fe 2+ , which further promoted the degradation and dechlorination of 2,4-D. The results of three consecutive experiments indicated the stability and reusability of catalyst. This study provides a potential method for the recycle of Fe-rich sludge as a novel and cost-effective catalyst for 2,4-D removal from aqueous environments, which is significant for the terminal disposal of Fe-rich sludge. Graphical Abstract
In this study, Al-doped NiFe 2 O 4 (NiAl x Fe 2-x O 4 ) was synthesized by the isomorphic substitution strategy, which was further employed for peroxymonosulfate (PMS) activation to remove 2,4-dichlorophenoxyacetic acid (2,4-D) in water. Doping of Al could construct oxygen vacancies (OVs) in the structure of NiAl x Fe 2-x O 4 , which further facilitates the exposure of metal sites for PMS activation. The removal rate of 2,4-D increased greatly compared to the NiFe 2 O 4 -activated process. By the density functional theory (DFT) process, it was verified that Al was more likely to replace Fe rather than Ni. OVs sites have the lowest adsorption energy of H 2 O ( E ads = -0.95 eV), and easily formed surface hydroxyl groups (–OH), which were further replaced by PMS (HSO 5 - ). The formed surface complex Me-O-O-SO 3 - was readily activated via electron transfer between O-O bond, thus promoting the cleavage of it and inducing SO 4 · - generation. This process induced the high performance of the NiAl x Fe 2-x O 4 /PMS system for effective 2,4-D degradation. Furthermore, the purified water showed relatively low toxicity. The present study proposed new insights into the interface mechanism of PMS triggering.
危险品化学品经营许可证（带存储）