纳米零价铁处理地下水污染技术研究进展

综述了纳米零价铁的合成、表征及在厌氧水体环境下对污染物质的降解和转化。重点分析了纳米零价铁还原含氯有机污染物和金属离子的特性和机理。总结了纳米零价铁技术尚需解决的问题和今后研究的方向。     

海藻酸钠负载纳米零价铁材料的制备及其对Cr（Ⅵ）的去除

纳米零价铁（Nano zero-valent iron,nZVI）易团聚、难以分离的特性影响了其在Cr（Ⅵ）修复中的广泛应用。为此，合成了海藻酸钠负载纳米零价铁的复合材料SA@nZVI，并对SA@nZVI材料的性能进行了研究。结果表明，SA@nZVI对Cr（Ⅵ）的具有良好的去除效果，而且反应过程中不易团聚，易分离；陈化时间的增加会降低SA@nZVI对Cr（Ⅵ）的去除率；SA@nZVI的重复利用次数为2次。最后探讨了各反应参数对SA@nZVI去除Cr（Ⅵ）的影响，提出了在实际应用SA@nZVI时的一些建议。     

改性纳米零价铁修复有机污染地下水研究现状

纳米零价铁具有粒径较小、反应活性高、比表面积大、能够迅速且更加完全的还原降解有机污染物的优点,在地下水污染修复中得到了广泛的应用。但其应用也存在不足之处:纳米零价铁易氧化而活性降低;易团聚,迁移性能不理想;容易使含水层介质颗粒空隙堵塞等。对纳米零价铁进行改性,克服其活性降低、易团聚及堵塞的问题,已成为环境领域一个重要的研究方向。介绍了几种纳米零价铁改性方法及其修复有机污染地下水研究现状。     

纳米级金属铁还原脱氯技术的改进研究

零价铁处理环境中有机卤化物、重金属等污染物是目前公认的一种有效的环境修复技术,具有良好的应用前景。但无论是金属铁可渗透反应墙还是铁纳米颗粒原位注射技术都存在缺陷,对零价铁反应性能的改进十分迫切。文章综述了国内外对零价铁反应性能改进的研究进展,详细介绍了当前最热门的铁纳米颗粒负载技术及铁纳米颗粒分散稳定技术对零价铁反应性能的改进机理及优势,指出了目前研究存在的一些问题,并对零价铁技术修复环境的工程应用提出了展望。     

纳米零价铁的优化技术及应用研究进展

纳米零价铁具有比表面积大、反应活性高等优点,被广泛应用于地下水和土壤环境修复中。但纳米零价铁容易团聚且极易被氧化的特点使其在环境中的应用受到了一定的限制,因此纳米零价铁的优化改性是此领域的研究热点。本文主要综述了纳米零价铁优化技术,包括物理辅助、纳米双金属、分散改性、固体负载等。此外,对纳米零价铁在环境中的应用进展作了总结。     

纳米零价铁的改性及其在废水处理中的应用综述

纳米零价铁比表面积大、反应活性高,近年来在水处理中展现出了许多优势,但其易于团聚和氧化的特点使其在实际应用中受到了一定的限制,因此需要采用适当的方法对纳米零价铁进行改性。作者综述了纳米零价铁在废水处理中的应用及研究进展,包括常用制备方法和对重金属、有机卤代物及硝酸盐等污染物的去除效能;还介绍了纳米零价铁在实际应用中存在的问题及其改性方法,并对该技术的应用前景进行了展望,提出改性方法在工程中的应用是未来的研究方向。     

纳米零价铁的制备、改性及场地应用研究进展

总结了纳米零价铁常用的制备技术,并比较了各种制备方法的优缺点,分析了纳米零价铁技术在实际应用中存在的问题,叙述了纳米零价铁4种改性方法的研究进展。介绍了国内外关于纳米零价铁技术的中试及场地治理的情况,分析了纳米零价铁工程化应用的制约因素,即纳米零价铁的高制备成本、在地下水流场中的迁移机制不明晰及所造成的生态环境风险难以评估等。认为纳米零价铁技术与生物技术、高级氧化技术、电化学技术等多种技术的联用是未来地下水环境修复治理的一个重要的研究方向,作为新兴的污染场地修复技术在我国有着巨大的发展空间及应用前景。     

纳米零价铁去除水中重金属铅、铬离子的研究

纳米零价铁(nanoscale zero-valent iron,nZVI)因其在重金属修复领域的潜在应用而备受关注。nZVI通常由零价铁(Fe~0)核和铁氧化壳结构组成,核壳结构不可避免地影响nZVI对重金属离子的去除性能。文章介绍了提高nZVI稳定性和分散性的新型绿色合成技术和nZVI的改性方法,重点综述了nZVI去除重金属铅、铬离子的反应机理以及去除过程的影响因素(nZVI投加量、pH值、反应温度和共存离子)。最后提出了nZVI合成过程中存在的科学问题并展望了nZVI在环境修复中的应用前景。     

生物炭负载纳米零价铁对水体典型污染物去除效果的研究进展

生物炭负载纳米零价铁(n ZVI@BC)作为一种绿色环保的新型纳米零价铁改性材料,因其对水体污染物具有良好的修复效果而被广泛应用。本文总结了近年来生物炭负载纳米零价铁在水体环境中的应用研究进展,综述了其制备过程和吸附机理,重点阐述了生物炭负载纳米零价铁对水体中的重金属污染、有机污染以及氮、磷污染的修复效果,并对该领域今后的研究前景进行了展望。     

包覆型纳米铁的制备及对氯酚类化合物的降解研究

利用自制的二氧化硅包覆型纳米零价铁在常温中性条件下还原降解了2,4,6-TCP,简要探讨了包覆型纳米零价铁的投加量和2,4,6-TCP初始浓度对降解效率的影响,并对其反应动力学进行了简要说明.降解反应过程符合一级反应动力学,表观反应速率常数Kobs=0.011 13 h-1.     

国外铁氧化物研究现状

综述了铁氧化物的不同制备方法,包括Fe(OH)2氧化法、缓慢或强制水解Fe3+盐溶液法、凝胶-溶胶法、水热法等方法。指出目前国外铁氧化物的研究趋势是纳米铁氧化物的制备,以及制备过程中开发特殊的添加剂或模板合成特定晶型和形态的晶体,以满足不同领域的应用要求。     

Iron-Based Nanoparticles for Toxic Organic Degradation: Silica Platform and Green Synthesis

Iron and iron oxide nanoparticles (NPs) are finding wide applications for the remediation of various toxic chloro-organic compounds (such as trichloroethylene, TCE), via reductive and oxidative processes. In this study, Fe NPs (30-50 nm) are synthesized by reduction from ferric ions immobilized (by ion exchange) on a platform (two types of sulfonated silica particles), in order to prevent the NP agglomeration. Next, the Fe NPs are oxidized and their effectiveness for the oxidative dechlorination of TCE via the heterogeneous decomposition of hydrogen peroxide to OH? on the surface of the iron oxide NPs was demonstrated. For the reductive approach, the use of ascorbic acid as a "green" reducing agent in conjunction with a secondary metal (Pd) inhibits NP oxidation and agglomeration through surface adsorbed species. The Fe/Pd NPs have been successfully applied for the dechlorination of TCE (k(SA), surface-area normalized reaction rate, = 8.1 ×10(-4) L/m(2)h).     

氢气还原氧化铁动力学的研究(英文)

Kinetics parameters of iron oxide reduction by hydrogen were evaluated by the isothermal method in a differential micro-packed bed.Influence of external diffusion,internal diffusion and heat transfer on the intrinsic reaction rate was investigated and the conditions free of internal and external diffusion resistance have been deter-mined.In the experiments,in order to correctly evaluate the intrinsic kinetics parameters for reducing Fe2O3 to Fe3O4,the reaction temperatures were set between 440 °C and 490 °C.However,in order to distinguish the reduc-tion of Fe3O4 to FeO from that of FeO to Fe,the reaction temperature in the experiment was set to be greater than 570 °C.Intrinsic kinetics of iron oxide reduction by hydrogen was established and the newly established kinetic models were validated by the experimental data.     

超低碳炼铁技术路径分析

2060年碳中和目标既使我国钢铁工业未来发展面临巨大挑战，又为其提供了换道超车的发展机遇。本文对绿氢直接还原、氧化铁熔融还原、碱性溶液电沉积铁、酸性溶液电沉积铁的发展历史和技术现状进行了综述。在全绿电炼铁场景下，本文对各种技术路线的理论和实际耗电进行了估算，从技术成熟度、电耗、技术难度、应用前景等方面，对各技术路径进行了对比分析，发现碱性溶液电沉积铁电耗最低，酸性溶液电沉积铁和电供热氢气熔融还原次之。从技术难度上看，氢气直接还原、酸性溶液电沉积铁技术难度较小，且都已完成一定规模的中试，氢气熔融还原炼铁、碱性溶液电沉积铁和氧化铁熔融电解炼铁技术都还处于概念或技术发展早期阶段。综合来看，氢气直接还原、酸性溶液电沉积铁和氢气熔融还原炼铁路线可望发展成为有竞争力的超低碳炼铁技术，而碱性溶液电沉积铁和氧化铁熔融电解炼铁技术难度较大，短期内恐难以取得较大突破。     

Synthesis by in situ chemical oxidative polymerization and characterization of polyaniline/iron oxide nanoparticle composite

Polyaniline (PANI) is a well‐studied material and is the pre‐eminent electrically conducting organic polymer with the potential for a variety of applications such as in batteries, microelectronics displays, antistatic coatings, electromagnetic shielding materials, sensors and actuators. Its good environmental as well as thermal stability and electrical conductivity tunable by appropriate doping make PANI an ideal active material for several applications. In this paper, we report the synthesis of water‐dispersible colloidal PANI/iron oxide composite nanoparticles using an in situ chemical oxidation polymerization method in a micellar medium of sodium dodecylsulfate, where the cores (iron oxide) are embedded in a PANI matrix layer. Transmission electron micrographs showed evidence of the formation of an iron oxide core/PANI shell composite with a thin layer of PANI over the iron oxide cores. The results of thermogravimetric, Fourier transform infrared and UV‐visible analysis indicated that the iron oxide nanoparticles could improve the composite thermal stability possibly due to the interaction between iron oxide particles and PANI backbone. We believe that the synthetic route described can also be adapted for the assembly of hierarchical structures of other metal oxides or hydroxides onto various cores. Copyright © 2010 Society of Chemical Industry     

Enhanced stability of Fe-modified CuO-ZnO-ZrO2-Al2O3/HZSM-5 bifunctional catalysts for dimethyl ether synthesis from CO2 hydrogenation

A series of iron (Fe) modified CuO-ZnO-ZrO2-Al2O3 (CZZA) catalysts,with various Fe loadings,were pre-pared using a co-precipitation method.A bifunctional catalyst,consisting of Fe-modified CZZA and HZSM-5,was studied for dimethyl ether (DME) synthesis via CO2 hydrogenation.The effects of Fe loading,reaction temperature,reaction pressure,space velocity,and concentrations of precursor for the synthesis of the Fe-modified CZZA catalyst on the catalytic activity of DME synthesis were investigated.Long-term stability tests showed that Fe modification of the CZZA catalyst improved the catalyst stability for DME synthesis via CO2 hydrogenation.The activity loss,in terms of DME yield,was significantly reduced from 4.2％ to 1.4％ in a 100 h run of reaction,when the Fe loading amount was 0.5 (molar ratio of Fe to Cu).An analysis of hydrogen temperature programmed reduction revealed that the introduction of Fe improved the reducibility of the catalysts,due to assisted adsorption of H2 on iron oxide.The good stability of Fe-modified CZZA catalysts in the DME formation was most likely attributed to oxygen spillover that was introduced by the addition of iron oxide.This could have inhibited the oxidation of the Cu surface and enhanced the thermal stability of copper during long-term reactions.     

Unprecedented Selective Oxidation of Styrene Derivatives using a Supported Iron Oxide Nanocatalyst in Aqueous Medium

Iron oxide nanoparticles supported on mesoporous silica‐type materials have been successfully utilized in the aqueous selective oxidation of alkenes under mild conditions using hydrogen peroxide as green oxidant. The supported catalyst could be easily recovered after completion of the reaction and reused several times without any loss in activity (no metal leaching observed during the reaction), constituting a facile and straightforward example of aqueous oxidation chemistry promoted by iron‐based heterogeneous systems.     

微生物合成金属纳米颗粒及在稠油催化降黏中的应用研究进展

纳米材料的传统制备包括化学、物理和机械方法,近年来,生物技术制备金属纳米颗粒因其经济和环保的优势引起了广泛的关注。本文首先阐述了微生物合成金属纳米颗粒的原理,总结了影响纳米颗粒生物合成的条件以及生物合成纳米颗粒及其在生物质中稳定分散的优势;然后讨论了使用污染物作为生物合成纳米颗粒前体,即当金属前体来自污染物和受污染的废水时,微生物合成纳米颗粒既降低了生产成本又处理了废液;并且探讨了纳米颗粒的应用对环境和人类健康的影响,强调在应用中应提前实地评估其环保可行性。最后,重点阐述了金属纳米颗粒在稠油催化降黏中的催化作用、纳米催化稠油降黏中的加氢反应和氧化反应;介绍了金属纳米颗粒辅助稠油原位开采的热采方法;展望了合成仿生复合纳米催化材料的应用前景。     

Hydroxyapatite-Coated SPIONs and Their Influence on Cytokine Release

Hydroxyapatite- or calcium phosphate-coated iron oxide nanoparticles have a high potential for use in many biomedical applications. In this study, a co-precipitation method for the synthesis of hydroxyapatite-coated nanoparticles (SPION^HAp), was used. The produced nanoparticles have been characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, Fourier transform infrared spectrometry, atomic emission spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area diffraction, and energy-dispersive X-ray spectroscopy. The results showed a successful synthesis of 190 nm sized particles and their stable coating, resulting in SPION^HAp. Potential cytotoxic effects of SPION^HAp on EL4, THP-1, and Jurkat cells were tested, showing only a minor effect on cell viability at the highest tested concentration (400 µg Fe/mL). The results further showed that hydroxyapatite-coated SPIONs can induce minor TNF-α and IL-6 release by murine macrophages at a concentration of 100 µg Fe/mL. To investigate if and how such particles interact with other substances that modulate the immune response, SPION^HAp-treated macrophages were incubated with LPS (lipopolysaccharides) and dexamethasone. We found that cytokine release in response to these potent pro- and anti-inflammatory agents was modulated in the presence of SPION^HAp. Knowledge of this behavior is important for the management of inflammatory processes following in vivo applications of this type of SPIONs.     

On the rate enhancement of ammonia synthesis over iron single crystals by coadsorption of aluminum oxide with potassium

The behavior of doubly promoted iron catalysts utilized for ammonia synthesis is modelled by the coadsorption of aluminum oxide and potassium on iron single crystal surfaces that were employed in high pressure reaction rate studies. The promoter effect of aluminum oxide is due to its interaction with iron oxide during the preparation stage of the industrial catalyst. After reduction, aluminum oxide stabilizes the most active Fe(111) and Fe(211) crystal surfaces. Potassium does not appear to be involved in the structural promotion but its presence on the active iron surfaces increases the rate of dinitrogen dissociation mostly by lowering the concentration of adsorbed ammonia thus, making more catalytic sites available for dinitrogen dissociation. Co-adsorbed potassium and alumina form a potassium aluminate compound that a) inhibits the aluminum oxide induced restructuring of iron and b) covers up the active iron sites for ammonia synthesis.