作者机构：
Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China
会议名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)
会议时间：
2015-11-18
会议地点：
重庆
会议论文集名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)论文集
摘要：
Iron and its oxides are ubiquitous and profoundly influence the environment through redox cycling of iron.In view of natural abundance and environmental benignancy of iron,the utilization of iron redox cycling for environmental remediation is very attractive,but still a challenge.In this study,we prepared nZVI with different iron oxide shell thickness and found that these nZVI exhibited interesting core-shell structure dependent reactivity on the Cr(Ⅵ) removal and aerobic degradation of 4-chlorophenol[1,2].We demonstrated the core-shell structure dependent Cr(Ⅵ) removal property of nZVI was mainly attributed to the reduction of Cr(Ⅵ) by the surface bound Fe(Ⅱ) besides the electrons transfer from the iron core to the adsorbed Cr(Ⅵ) through the iron oxide shell.Characterization results revealed that the core-shell structure dependent aerobic oxidative reactivity of nZVI was arisen from the combined effects of incrassated iron oxide shell and more surface bound ferrous ions on amorphous iron oxideshell formed during the water-aging process.The incrassated iron oxide shell would gradually block the outward electron transfer from iron core for the subsequent two-electron molecular oxygen activation,but more surface bound ferrous ions on iron oxideshell with prolonging ageing time could favor the single-electron molecular oxygen activation,which was confirmed by electron spin resonance spectroscopy with spin trap technique.
作者机构：
Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, People's Republic of China
会议名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)
会议时间：
2015-11-18
会议地点：
重庆
会议论文集名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)论文集
摘要：
In this study,we demonstrate that hydrothermal synthesized FeS2 (syn-FeS2) is highly efficient to catalyze the H2O2 decomposition for the alachlor degradation.The alachlor degradation rate of syn-FeS2 heterogeneous Fenton system was almost 55 times that of commercial pyrite (com-FeS2) counterpart at an initial pH of 6.2.Experimental results revealed that the alachlor oxidation enhancement in the syn-FeS2 Fenton system was attributed to the molecular oxygen activation induced by more surface bound ferrous ions on syn-FeS2.The molecular oxygen activation process could generate superoxide anions to accelerate the Fe(Ⅱ)/Fe(Ⅲ) cycle on the syn-FeS2 surface,which favored the H2O2 decomposition to generate more hydroxyl radicals for the alachlor oxidation.It was found that the hydroxyl radicals generation rate constant of syn-FeS2 Fenton system was 71 times that of com-FeS2 counterpart,and even 1-3 orders of magnitudes larger than those of commonly used Fe-bearing heterogeneous catalysts,respectively We detected the alachlor degradation intermediates with gas chromatography-mass spectrometry to tentatively propose a possible alachlor degradation pathway.These interesting findings could provide some new insights on the molecular oxygen activation induced by FeS2 minerals and the subsequent heterogeneous Fenton degradation of organic pollutants in the environment.
通讯机构：
[Zhang, Lizhi] C;Cent China Normal Univ, Coll Chem, Minist Educ, Key Lab Pesticide & Chem Biol, Wuhan 430079, Peoples R China.
摘要：
Ordered 2D nanostructural BiOI nanoflake arrays decorated with Bi2S3 nanospheres have been designed and in situ fabricated for the first time, to form BiOI/Bi2S3 bulk heterojunctions through a soft chemical route. A modified successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate BiOI nanoflake arrays on flexible ITO/PET substrates at room temperature. The degree of transformation of BiOI to Bi2S3 was controlled through the adjustment of exposure time of the BiOI/ITO substrate to thioacetamide (TAA) aqueous solution. The morphologies of BiOI, BiOI/Bi2S3 heterojunctions and Bi2S3 films were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) patterns, and high resolution transmission electron microscopy (HRTEM). The presence of Bi2S3 was further validated through Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Especially, photoelectrochemical measurements demonstrated that such a Bi2S3 decorated BiOI photoanode based cell exhibits significant augments of short-circuit current density (J(sc)) and incident photon-to-current conversion efficiency (IPCE, 3 times higher than the pure BiOI photoanode), attributable to the stronger photo-absorption and better photogenerated charge carrier separation and transport efficiency. The surface photovoltage (SPV) measurements further confirmed the importance of BiOI/Bi2S3 heterojunctions in such PEC cells. This solution-based process directly on flexible ITO offers the promise for low-cost, large-area, roll-to-roll application of the manufacturing of the third generation thin-film photovoltaic devices.
摘要：
In this study,we demonstrate that the addition of phosphate could significantly promote the oxygen activation performance of Fe@Fe2O3 core-shell nanowires to generate more reactive oxygen species (ROS).The rotating ring disk electrochemical analysis revealed that the low ROS yield of Fe@Fe2O3 core-shell nanowires was ascribed to their nearly four-electron oxygen reduction to H2O in the absence of phosphate.Interestingly,the addition of phosphate could shift the nearly four-electron molecular oxygen reduction to around one-electron proton reduction to hydrogen radical,which subsequently facilitated ROS generation.This study provides a new method to improve the ROS yield of zero-valent iron induced oxygen activation process.
作者机构：
Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental Chemistry, College of Chemistry, Central China Normal University, Wuhan 430079, China
会议名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)
会议时间：
2015-11-18
会议地点：
重庆
会议论文集名称：
2015 International Symposium on Environmental Science and Technology (2015 ISEST)(2015环境科学与技术国际会议)论文集
摘要：
In this study,we systematically investigated the removal of bromate with core-shell Fe@Fe2O3 nanowires (CSFN) at neutral pH,especially the effects of surface bound ferrous ions and molecular oxygen.Although the hypobromous acid (HBrO) intermediate was generated at the initial stage,it could finally be oxidized to Br-with 100% recovery.We interestingly found ferrous ions bound on the surface of CSFN could directly reduce bromate,and also act as an electron mediator to accelerate the transfer of electron from the inner iron core to the iron oxide shell,thus contributed to the BrO3-removal.Moreover,molecular oxygen could compete electrons from either Fe2+ or Fe0 to generate reactive oxygen species (·O2,H2O2,·OH),during the bromate removal process.Among these reactive oxygen species,·O2-and H2O2 promoted the bromate removal,but ·OH exhibited an inhibition effect.On the basis of bromide species analyses and CSFN characterization results,we proposed a bromate removal mechanism of core-shell Fe@Fe2O3 nanowires.This study can deepen our understanding on the bromate removal with zero valent iron,and also shed light on the design of advanced bromate removal materials.
