氮掺杂碳纳米管的合成及活化过一硫酸盐的性能与机理

Synthesis of Nitrogen-doped Carbon Nanotubes and the Performance and Mechanism of PMS Activation

以多壁碳纳米管(MWCNT)为原材料,三聚氰胺为氮前体,采用高温煅烧法制得了含氮量约3.33%(摩尔分数)的氮掺杂碳纳米管(N-CNT-700),该纳米管为一维材料.N-CNT-700活化过一硫酸盐(PMS)体系60 min内对苯酚的降解效率可达100%,总有机碳(TOC)去除率可达61.6%,体系的活化能为35.4 kJ/mol.通过电子顺磁共振(EPR)检测、掩蔽实验及PMS浓度测定等方式确定了体系降解机制为自由基(·OH,SO4·−)与非自由基共同作用,除去9%的吸附去除外,91%的氧化降解中自由基作用占比约49%,单线态氧(1O2)作用占比约18%,活性中间体作用占比约24%.N-CNT-700的反应活性随着重复利用次数的增加而降低,高温处理可以恢复其高反应活性.煅烧温度影响材料中的氮含量及种类,N-CNT的反应活性与氮含量成正比,且与石墨氮含量密切相关.

Using multi-wall carbon nanotubes(MWCNT)as raw materials and melamine as a nitrogen precursor,a nitrogen-doped carbon nanotube(N-CNT-700)with a nitrogen content of about 3.33%(molar fraction)was prepared by high-temperature calcination.N-CNT-700 is a one-dimensional tubular nanomaterial,the degradation efficiency of phenol can reach 100%,and the total organic carbon(TOC)removal rate can reach 61.6%,and the activation energy of the system is 35.4 kJ/mol within 60 min in N-CNT-700 activated PMS system.Through electron paramagnetic resonance(EPR)detection,quenching experiment and PMS concentration determination,the degradation mechanism of the system was determined to be free radicals(·OH,SO4·−)and non-free radicals,in addition to 9%adsorption removal,in the 91%oxidative degradation,free radicals account for about 49%,1O2 for about 18%,and active intermediates for about 24%.The reactivity of N-CNT-700 decreases as the number of reuses increases,and high temperature treatment can restore its high reactivity.The calcination temperature affects the nitrogen content and types of the material.The reactivity of N-CNT is proportional to the nitrogen content and is closely related to the nitrogen content of graphite.