Preparation of highly-conductive pyrogenic carbon-supported zero-valent iron for enhanced Cr(VI) reduction
Preparation of highly-conductive pyrogenic carbon-supported zero-valent iron for enhanced Cr(VI) reduction
复制标题
制备高导电热解碳载零价铁以增强 Cr(VI) 还原
DOI：
10.1016/j.jhazmat.2020.122712
复制
发表时间：
2020-09-05
影响因子：
13.6
通讯作者：
Fu, Weizhang
中科院分区：
文献类型：
--
作者：
Zhao, Mingyue;Zhang, Changai;Fu, Weizhang
本文研究了以赤铁矿（α-Fe_2 O_3）处理的松木为原料，热解制备的热解碳（PC）负载零价铁（ZVI/PC）还原铬酸盐（Cr（VI））过程中PC的电子转移（ET）部分。X-射线衍射分析表明，样品的相结构为α-Fe_2 O_3-磁铁矿（Fe_3 O_4）->浮氏体（FeO）-> ZVI（Fe度）。拉曼光谱和Brunauer-Emmett-Teller分析表明，ZVI/PC具有比原始PC更有序的石墨碳和更大的表面积。根据Langmuir等温模型预测，PC、ZVI/PC和ZVI对Cr（VI）的最大去除能力分别为5.78、36.12和8.39g kg（-1）。ZVI/PC在pH 3-9范围内对Cr（VI）的去除能力显著高于ZVI和PC，但在pH 4及以上时，Cr（VI）去除率迅速下降至6.78 g kg（-1）。X射线光电子能谱和连续解吸的铬负载ZVI/PC和ZVI显示三价铬是占主导地位的物种，表明还原是一个重要的机制，铬（VI）解毒。电化学分析表明，ZVI/PC具有更大的Tafel腐蚀速率和ET量，具有更低的电阻。此外，Cr（VI）的还原与ZVI/PC的电阻呈相反趋势。综上所述，ET容量与ZVI/PC的导电性密切相关，这是由于在较高的热解温度下PC的导电石墨碳结构增强。
In this work, electron transfer (ET) moiety of PC was ascertained in chromate (Cr(VI)) reduction by zero-valent iron supported by pyrogenic carbon (PC) (ZVI/PC) prepared by pyrolysis of hematite (alpha-Fe2O3)-treated pine-wood. X-ray diffraction analysis suggested successive phase transformation of alpha-Fe2O3 -magnetite (Fe3O4)-> wustite (FeO)-> ZVI (Fe degrees). Raman spectra and Brunauer-Emmett-Teller analysis revealed that ZVI/PC is characterized with more ordered graphitic carbon and greater surface area than pristine PC. Maximal Cr(VI) removal capacity (pH = 3) as predicted by Langmuir isotherm model were 5.78, 36.12 and 8.39g kg(-1) for PC, ZVI/PC and ZVI, respectively. ZVI/PC maintained significantly greater Cr(VI) removal capacity than ZVI and PC at pH 3-9, but Cr(VI) removal dropped rapidly to 6.78 g kg(-1) at pH 4 and above. X-ray photoelectron spectroscopy and successive desorption of Cr-laden ZVI/PC and ZVI showed trivalent Cr was the dominant species, suggesting reduction was an important mechanism for Cr(VI) detoxification. Electrochemical analysis demonstrated that ZVI/PC exhibited greater Tafel corrosion rate and ET quantity, with lower electrical resistance. Besides, Cr(VI) reduction showed reversal trend with electrical resistance of ZVI/PC. To conclude, ET capacity was closely associated with electrical conductivity of ZVI/PC due to intensified conducive graphitic carbon structure of PC at higher pyrogenic temperatures.