混合价态铁基金属有机框架催化过氧乙酸高效降解对硝基苯酚

Peracetic acid activation for efficient degradation of p-nitrophenol by mixed-valence iron-based metal-organic framework

为提升铁基金属有机框架(Fe-MOFs)对印染废水深度处理的效能,采用原位掺杂溶剂热技术制备了混合Fe(Ⅱ)/Fe(Ⅲ)价态MIL-53(Fe)(MV-MIL-53(Fe))催化剂。借助X射线粉末衍射仪、场发射扫描电镜、氮气吸附仪和吡啶吸附红外光谱仪等对MV-MIL-53(Fe)晶体结构、微观形貌、孔结构和表面酸位等本征结构进行了测试分析。选取对硝基苯酚(4-NP)作为印染废水模型污染物,以过氧乙酸(PAA)为氧源,研究了MV-MIL-53(Fe)催化PAA降解4-NP的性能和关键活性物种。结果表明:Fe(Ⅱ)的引入提高了MIL-53(Fe)表面Lewis酸位密度,为PAA催化活化提供了更丰富更高效的活性位点;MV-MIL-53(Fe)/PAA体系对4-NP的降解速率常数高达0.0521 min^(-1),分别是MV-MIL-53(Fe)/H_(2)O_(2)、MIL-53(Fe)/PAA和MIL-53(Fe)/H_(2)O_(2)体系的2.05、1.45和6.68倍,且MV-MIL-53(Fe)重复循环使用5次后仍保持良好的结构稳定性和催化降解性能;羟基自由基(·OH)是MV-MIL-53(Fe)催化PAA快速降解4-NP的关键活性物质。

In order to improve the advanced treatment efficiency of iron-based metal-organic frame-works(Fe-MOFs)for printing and dyeing wastewater,mixed-valence MIL-53(Fe)(MV-MIL-53(Fe))containing Fe(Ⅱ)and Fe(Ⅲ)was prepared by an in-situ doping solvothermal approach.The MV-MIL-53(Fe)was systematically characterized with X-ray diffraction,scanning electron microscopy,nitrogen adsorption equipment,and pyridine chemisorbed infrared spectroscopy.p-nitrophenol and peracetic acid(PAA)were selected as the model target and green oxidant respectively to study the degradation activity and major active species of MV-MIL-53(Fe).The results show that Fe(Ⅱ)dopant increased the Lewis acidity of MIL-53(Fe),thus offering more active sites for PAA activation.The 4-NP degradation kinetic rate constant of MV-MIL-53(Fe)/PAA system could reach to 0.0521 min^(-1),which was 2.05,1.45,and 6.68 times higher than MV-MIL-53(Fe)/H_(2)O_(2),MIL-53(Fe)/PAA,and MIL-53(Fe)/H_(2)O_(2)counterparts,respectively.After successive cycling for five runs,the MV-MIL-53(Fe)still exhibited good structure stability and catalysis activity for 4-NP degradation using PAA.Hydroxyl radicals were verified as the main reactive species converting from PAA for the rapid degradation of 4-NP.