掺杂镍的纳米铁及其转化产物—FeOOH耦合去除对氯硝基苯及其还原产物效能与机制

Efficiency and mechanism of coupling removal of p-chloronitrobenzene and its reduction products by Ni-doped n-Fe and its transformation produdct—FeOOH

以掺杂了Ni的纳米铁及其转化产物耦合去除对氯硝基苯及其脱氯产物,探讨了耦合去除的效能、历程和机制.结果表明,m(Ni)/m(Fe)分别为8%和12%的纳米铁/镍(n-Fe/Ni)不仅能在20 min内将对氯硝基苯的硝基还原产物—对氯苯胺近乎100%脱氯还原为苯胺,而且在反应36 h后,其转化产物可将苯胺的浓度降至接近于0 mg·L^(-1). X-射线衍射和透射电镜的表征结果表明,反应8 h后,Fe(0)主要被氧化为板条状纤铁矿(γ-FeOOH)和针状的针铁矿(α-FeOOH).耦合去除历程与机制为:Fe(0)提供电子使对氯硝基苯被还原为对氯苯胺,其腐蚀产物H;在Ni催化下解离为活性氢原子(H*).H*进攻对氯苯胺的C—Cl键使其脱氯还原为苯胺,苯胺随后被Fe(0)的转化产物α/γ-FeOOH吸附固定,从而使对氯硝基苯及苯胺从水中彻底去除.

The coupling removal of p-chloronitrobenzene and its dechlorination products by Ni doped nano-iron(n-Fe),as well as its conversion products are investigated in this study.The efficiency,process and mechanism of coupling removal are also examined.The results show that the Fe/Ni nanoparticles(n-Fe/Ni)with m(Ni)/m(Fe)ratios of 8% and 12%,almost completely reduce the nitroreduction product of p-chloronitrobenzene to aniline within 20 min.In addition,the concentration of aniline is reduced to nearly zero(0)after 36 h of reaction.The X-ray diffraction spectra and transmission electron microscopy indicated the oxidization of the Fe(0)into lath-like lepidocrocite(γ-FeOOH)and needle-like goethite(α-FeOOH)after 8 h of reaction.The coupling removal process and mechanism are as follows,Fe(0)provides electrons to reduce p-chloronitrobenzene to p-chloroaniline,and its corrosion product H;is dissociated into active hydrogen atom(H*)under the catalysis of Ni.H* attacks the C—Cl bond of p-chloroaniline to reduce it to aniline,which is then adsorbed and fixed by the Fe(0) conversion product(α/γ-FeOOH),thus removing p-chloronitrobenzene and aniline from the wastewater completely.