Study On Catalytic Performance Of Co/Ni/Fe Layered Double Hydroxides In The Degradation Of Nitrobenzene

Nitrobenzene is a kind of high toxic organic material,which is difficult to be degraded by traditional methods,such as physical methods and biological methods.In this paper,Co-Fe LDH and Co/Ni/Fe LDHs were first used in Fenton-like reaction for the degradation of nitrobenzene.The research outcomes were listed as follows:1.Co-Fe LDH synthesized by coprecipitation method were characterized by XRD?SEM and BET.The results indicated that the catalyst was successfully synthesized with the typical layer structure.The catalytic activity was tested and the results showed Co-Fe LDH was an efficiency catalyst for the degradation of nitrobenzene in Fenton-like system.Nitrobenzene?50 mg/L?could be completely degraded in 30 min with pH 2.7,the concentration of H₂O₂?500 mg/L?,Co-Fe LDH?1g/L?,and the TOC removal was more than 75%.2.Three kinds of different ratios of Co/Ni/Fe LDHs?1.5:0.5:1?,?1:1:1?,?0.5:1.5:1?were synthesized and characterized by XRD?SEM and BET.The test results showed that the Co/Ni in Co/Ni/Fe LDHs would have an influence on the degradation of nitrobenzene.The catalytic activity decreased with the ratio of Co/Ni decreased and Co/Ni/Fe LDHs?1:1:1?was the most appropriate catalyst under present experiment condition.3.Tert-butyl alcohol quenching,LC-MS and TOC analysis were used for study of nitrobenzene degradation mechanism,and the result showed that the mechanism in Co-Fe LDH/H₂O₂ and Co/Ni/Fe LDHs/H₂O₂ system was radical mechanism.The major intermediates,including 2-nitrophenol,3-nitrophenol,4-nitrophenol were identified by LC-MS.The nitrophenol were finally mineralized to CO₂ and H₂O.