An old story with new insight into the structural transformation and radical production of micron-scale zero-valent iron on successive reactivities  

作　　者：Xinhao Wang Xueting Pu Yue Yuan Yunjie Xiang Yuling Zhang Zhaokun Xiong Gang Yao Bo Lai 

机构地区：[1]State Key Laboratory of Hydraulics and Mountain River Engineering,College of Architecture and Environment,Sichuan University,Chengdu 610065,China [2]Sino-German Centre for Water and Health Research,Sichuan University,Chengdu 610065,China [3]National Engineering Laboratory for Clean Technology of Leather Manufacture,College of Biomass Science and Engineering,Sichuan University,Chengdu 610065,China [4]Institute of Environmental Engineering,RWTH Aachen University,Aachen 52062,Germany

出　　处：《Chinese Chemical Letters》2020年第10期2634-2640,共7页中国化学快报（英文版）

基　　金：the financial support from China Postdoctoral Science Foundation(No.2019T120843);Sichuan Science and Technology Program(No.2019YJ0091)。

摘　　要：It is generally recognized that the formation and accumulation of iron oxides on the surface of zero-valent iron(Fe^(0))resulting in significant decrease of contaminant degradation rates during the long-term reactions.However,in this study,we found that the removal efficiencies of p-nitrophenol(PNP)by micro zero-valent iron(mFe^(0))could maintain at the satisfactory level in the process of continuous reactions(20 cycles).The removal rate constant(0.1779 min^(-1))of the 5th cycle was 6.74 times higher than that of the 1streaction(0.0264 min^(-1)),even the 20th cycle(0.0371 min^(-1))was higher than that of the 1st reaction.Interestingly,almost no dissolved iron was detected in the solution,and the total iron concentrations decreased dramatically with the process of continuous reactions.The results of scanning electron microscope and energy dispersive spectrometry(SEM-EDS)and X-ray diffraction(XRD)revealed that the structure and composition of corrosion products change from amorphous to highly crystal with the increase of the number of cycles.The corrosion products were mainly magnetite(Fe_(3)O_(4))and a small part of maghemite(γ-Fe_(2)O_(3)),which were in the form of micro sphe res on the surface of mFe^(0).The formation of surface oxidation shell hindered the release of Fe^(2+).X-ray photoelectron spectroscopy(XPS)results illustrated that partial Fe3O_(4) could be converted into y-Fe_(2)O_(3).Electrochemical analysis proved that the electron transfer rate of mFe^(0) increased with the formation of the oxides shell.However,the consumption of iron core and thicker oxide film weakened the electron transfer rate.Besides,the quenching experiments indicated that the reaction activity of mFe^(0) could be enhanced with the addition of scavengers.This study deepened the understanding of the structural transformation and radical production of mFe^(0) in continuous reactions.

关 键 词：Zero-valent iron Iron oxides P-NITROPHENOL Structural transformation Successive reactivities 

分 类 号：O614.811[理学—无机化学] X505[理学—化学]