Search query: Fe0 carbon nanotubes

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abstract: Abstract Multi walled carbon nanotubes (MWCNTs) have been used as catalysts or supports in many industrial applications. Therefore, we provide a low cost and environmentally friendly route to synthesize MWCNTs from plastics and red mud (RM) which is beneficial to the disposal of waste solid. This nano materials (RM CNTs) are used as novel catalysts for CGPO to remove SO2 and NO from flue gas. It was unexpected that RM CNTs exhibit a different catalytic pathway from the RM catalyst (traditional Fenton like reaction) result from the constrained nano scale reaction in which Fe3O4/Fe0/Fe3C nanoparticles were encapsulated in MWCNTs. Combined with various quenching experiments and characterization analysis, the catalytic mechanism of RM CNTs was clarified: (1) the in situ carbothermal reduction increased the activity of the catalysts (Fe2O3 Fe3O4 Fe0 Fe3C) (2) Fe0 and Fe3O4 can form a metal semiconductor interface with extremely low resistance which can accelerate electron transfer; (3) Fe3C as heterogeneous Fenton catalyst was rarely reported. The experimental results indicated that the activity of Fe C bond was closely related to the type of carbon substrate during the formation process; (4) MWCNTs encapsulated Fe3O4/Fe0/Fe3C particles exhibited excellent catalytic activity, which was due to the existence of 1O2.
author_names: Siyuan Yang

Dan Xu

Wenjie Yan

Yuanquan Xiong
title: Effective NO and SO2 removal from fuel gas with H2O2 catalyzed by Fe3O4/Fe0/Fe3C encapsulated in multi walled carbon nanotubes
year: 2021

abstract: In this work, nitrogen doped carbon nanoshell structure with the encased Fe0/Fe3C nanoparticles (Fe@NC) was synthesized with a solvent free method via direct carbonizing the ground mixture of dicyandiamide and ferric chloride hexahydrate. The morphology, structure, and surface properties of as synthesized Fe@NC were characterized systematically, and the removal performance of Fe@NC towards U(VI) was studied in detail. The results manifested that the Fe@NC possessed large surface area (127.0 m2/g) with mesoporosity and the encapsulated Fe0/Fe3C nanoparticles were concentrated at the tip of N doped carbon nanotubes. Moreover, the Fe@NC hybrid material exhibited the maximum removal capacities of 0.85 and 0.44 mg/m2 at pH 4.5 and 1.5, respectively. The mechanism of U(VI) removal by the Fe@NC was attributed to the synergistic effects of adsorption via nitrogen/oxygen containing groups and redox reaction between Fe0/Fe2+ and U(VI)
author_names: Kairuo Zhu

Gang Song

Xuemei Ren

Changlun Chen
title: Solvent free engineering of Fe0/Fe3C nanoparticles encased in nitrogen doped carbon nanoshell materials for highly efficient removal of uranyl ions from acidic solution.
venue: Journal of colloid and interface science
year: 2020

abstract: In this study, bamboo like nitrogen doped carbon nanotubes (BN CNTs) are successfully deposited on etched iron mesh (d Fe) using chemical vapor deposition (CVD) method with acetonitrile as precursor. The acidic etching process is necessary for the special BN CNTs structure formation by exposing more Fe0 sites. The BN CNTs/d Fe is then evaluated for the electrochemically assisted PMS activation to degrade phenol. Under cyclic voltammetry (CV, 0 1 V vs. RHE) assistant, 20 ppm phenol can be degraded in 30 min with a rate constant of 0.2837 min 1, ~78 times more than that without CV. Some Fe3+ species in the catalyst will be reduced at the initial stage, a two step pseudo first order kinetic is thus used for the degradation curves fitting. Both the structure defects and doped nitrogen atoms are responsible for the high catalytic activity of BN CNTs. According to the quenching tests, both radical and non radical processes are present for PMS activation, thus obtaining enhanced organics removal efficiency. The electrochemically assistant could enhance the PMS adsorption on the electrode as well as electrons transfer between Fen+ and PMS, thus increasing the PMS activation efficiency. The utilization of earth abundant Fe mesh for the fabricating free standing electrodes provide a potential low cost and effective strategy of waste water remediation.
author_names: Di Wu

Yang Zhao

Qing Xia

Xiaobin Fan

Yang Li

Guoliang Zhang

Fengbao Zhang

Wenchao Peng
title: Bamboo like nitrogen doped carbon nanotubes on iron mesh for electrochemically assisted catalytic oxidation.
venue: Journal of hazardous materials
year: 2020

abstract: Abstract This paper reported a novel iron carbon hybrid material (Fe 0 CNTs) as a technical improvement of internal electrolysis for water treatment. This material was fabricated by means of electrophoresis deposition (EPD) to immobilize carbon nanotubes on the surface of zero valent iron plate and then stabilized by calcinations. The reactivity of Fe 0 CNTs was examined by the degradation kinetics of methylene blue (MB) used as model compound. The presence of Fe 0 CNTs material in water induced considerable enhancement in reaction rates, which was attributed to the numerous microscopic iron carbon galvanic cells formed in situ. The oxidative pretreatment of carbon nano tubes largely facilitated the electrochemical process due to the improvement in surface chemistry. The thickness of CNTs layer was optimized at about 10 mm (EPD time of 3 min) for a better performance of Fe 0 CNTs. The Fenton like oxidation chain reactions following Reactions (1) (3) was verified to play the key role on the degradation of target organics. The direction of this pathway has been analyzed to depend on a complex stoichiometrical relation between hydrogen ion (H and dissolved oxygen (DO) since side reactions may also take place consuming both of them. This functionalized Fe 0 CNTs material working through micro electrolysis exhibited appreciable advantages in terms of reactivity, durability and operational simplicity. The knowledge gained from the effect of solution environments is of importance for process control.
author_names: Shuo Zhang

Dong Jun Wang

Liang Zhou

Xingwen Zhang

Pingping Fan

Xie Quan
title: Intensified internal electrolysis for degradation of methylene blue as model compound induced by a novel hybrid material: Multi walled carbon nanotubes immobilized on zero valent iron plates (Fe0 CNTs)
year: 2013

abstract: Abstract Regarding that solution pH is often a limiting factor for ozone technology, composite heterogeneous catalyst was developed accordingly in this work by virtue of carbon nanotube and zero valent iron. This hybrid material labeled as Fe0 CNTs was deliberately prepared by immobilizing oxidized multi walled carbon nanotubes (CNTs) onto the surface of zero valent iron plates through electrophoresis deposition (EPD) and high temperature calcinations. The catalytic effect of Fe0 CNTs during ozonation was examined by comparative study on degradation of methylene blue (MB) as model compound. Fe0 CNTs material, as expected, exhibited appreciable pH adaptability with high performance either in acidic (pH 3) or basic (pH 9) conditions, while follow dissimilar catalytic pathway as analyzed referring to material characterization by X ray photoelectron spectroscopy (XPS) The surface localized layer of CNTs was considered for pH 3 to act mainly as active mediator sensitizing zero valent iron and promote catalytic process, whereas for pH 9 it would play a role as effective ozone catalyst. The superiority for use of CNTs as carbon material was also reflected by comparison with granular activated carbon (GAC) on decolorization kinetics. Time of EPD was experimentally optimized to be 3 min for a better capability of Fe0 CNTs in catalytic ozonation.
author_names: Shuo Zhang

Dong Wang

Xie Quan

Liang Zhou

Xingwen Zhang
title: Multi walled carbon nanotubes immobilized on zero valent iron plates (Fe0 CNTs) for catalytic ozonation of methylene blue as model compound in a bubbling reactor
year: 2013

abstract: Abstract Highly efficient and acid corrosion resistant for carbon adsorbent in hexavalent chromium removal is a significant property in the practical application. In this study, nitrogen doped carbon nanotubes with encapsulated Fe and Fe3C were synthesized through a facile pyrolysis procedure using melamine and ferric chloride as precursors, displaying an excellent efficiency and stability for hexavalent chromium removal. High maximum removal capacities with 35.26 and 970.87 mg g 1 were obtained in neutral and acid solutions, respectively, due to the adsorption process, reduction reaction between Fe0 or Fe2+ nanoparticles and Cr(VI) ions. The unexpected high stability in acid solution (pH at 1) after five recycles was observed for the first time, ascribed to N doping and the tubular structure with encapsulated ferric carbide, which could be resistant to the acid corrosion. After a simple treatment, the used adsorbent could be re utilized as catalysts for the electrochemical reduction of CO2 with high faradic efficiency (over 90% total efficiency and about 50% for CO production at 0.6 V) demonstrating a promising potential for reutilizing the used carbon adsorbents.
author_names: Ju Zhang
title: Highly efficient and acid corrosion resistant nitrogen doped magnetic carbon nanotubes for the hexavalent chromium removal with subsequent reutilization
venue: Chemical Engineering Journal
year: 2019

abstract: The transition metal modified carbon materials as multifunctional cathode for electro Fenton (EF) is supposed to be promising to generate H2O2 in situ and catalyze it to form hydroxyl radicals to degrade organic pollutants, but still facing the challenge of reduced activities of heterogeneous catalyst and poor stability due to continuous leaching of active metals. Herein, a heterogeneous cathode on which iron confined interior cavity of carbon nanotubes (Fe0 in CNTs) with extreme lower leached iron was prepared, observing a much higher H2O2 yield and phenol removal rate (9.68 times faster) when compared with that of iron confined external walls of CNTs (Fe0 out CNTs) It was found that iron valence on CNTs played an important role on the heterogeneous Fenton activity, supporting that Fe0 was beneficial for H2O2 selectivity of 2e process (2.43 times higher) and phenol removal rate (21.44 times faster) other than iron oxide. It was confirmed that CNTs cavity could provide isolated space for Fe0, making the iron leaching mass was only 3.21x 10 3 mg/cm2 even at pH 3. Consequently the different mechanism for phenol degradation by heterogeneous EF on Fe0 in CNTs and Fe0 out CNTs cathode was disclosed. It supported that heterogeneous Fenton like reaction on CNTs surface rather than solution homogeneous Fenton reaction played a decisive role on pollutant degradation. Furthermore, the cathode reusability was proved to be dependent on the Fe0 content and its efficient conversion between FeIII/FeII. This work verified the importance of confinement catalysis in selective controlling the position and valence of iron on CNTs, which could effectively increase heterogeneous EF activity and decrease the leached iron to improve cathode stability. Thereby it would make a significant breakthrough in heterogeneous EF and shed light on the confinement catalysis method for organic pollutants degradation.
author_names: Pei Su

Minghua Zhou

Gengbo Ren

Xiaoye Lu

Xuedong Du

Ge Song
title: Carbon nanotubes confined iron modified cathode with prominent stability and activity for heterogeneous electro Fenton
year: 2019

abstract: Abstract In this work, a catalytic CVD process using ethanol as carbon source was used to convert an iron rich waste, i.e. red mud (RM) in a magnetic composite. TPCVD (temperature programmed CVD) XRD, Mossbauer, EDS, magnetic measurements, TG/DTA, CHN, BET, Raman, SEM and TEM showed that ethanol gradually reduces the iron phases in the RM to Fe3O4 at 500 degC and to Fe1 xO at 600 degC. At higher temperatures Fe0 and Fe carbide are the main phases produced with the formation of large amounts of carbon (30 50 wt% especially as nanotubes and nanofibers. These magnetic materials can be separated into two fractions by simple dispersion in water, i.e. a settled material composed of large magnetic particles and the suspended material composed of nanoparticles with average size of 10 100 nm. The carbon in the composites can be activated with CO2 increasing the surface area from 79 to 185 m2 g 1. The magnetic composites were used as adsorbent of model dyes methylene blue and indigo carmine showing excellent results. The composites were also used as support to produce a recyclable Pd catalyst. Tests for the 1,5 cyclooctadiene hydrogenation showed that the catalyst can be easily magnetically separated from the reaction medium and reused for five consecutive times with no deactivation or change in selectivity.
author_names: Aline A S Oliveira

Juliana Cristina Tristao

Jose D Ardisson

Anderson Dias

Rochel M Lago
title: Production of nanostructured magnetic composites based on Fe0 nuclei coated with carbon nanofibers and nanotubes from red mud waste and ethanol.
year: 2011

abstract: Abstract In heterogeneous Fenton, nanostructured iron catalysts with confinement effect greatly improve the effectiveness for organic pollutants removal, however, this effect dependence on the space of substrate remains unclear and thereby limit the application of confined catalysis. Herein, Fe particles encapsulated in carbon nanotubes with inner diameter of 3 30 nm (Fe0@CNTs (x) were prepared and tested as catalysts to degrade model pollutant of phenol and four phenolic compounds (p diphenol (p DP) p aminophenol (p AP) p nitrophenol (p NP) and p chlorophenol (p CP) With the increasing of CNTs inner diameter from 3 to 30 nm, the encapsulated Fe particles linearly increased from 2.68 to 14.75 nm. The confinement effect was significant in the range of 3 7 nm of CNTs cavity, especially at 5 nm, which was critical to decrease iron leaching and enrich hydroxyl radical generation for efficient pollutants removal by surface heterogeneous reaction (2.13 folds compared with the homogeneous Fenton) In addition, the Fe0@CNTs (3) (7) with positive charges was conductive to adsorb the negatively charged phenols (p DP and p AP) compared with non spatial confinement of Fe CNTs with negative charge. According to the experiment and DFT calculations, the quantitative structure activity relationship about electron transfer was established, indicating that the electron from highest occupied molecular orbital (HOMO) of p AP could migrate to lowest unoccupied molecular orbital (LUMO) of Fe0@CNTs and further to HOMO of Fe0@CNTs. The electron in HOMO of Fe0@CNTs could migrate into H2O2 to generate *OH. This finding suggested a new paradigm to fulfill selective oxidation of the pollutants with electron withdrawing group by suitable heterogeneous catalysts having significant confinement effect with more effective utilization of *OH in Fenton reaction.
author_names: Pei Su
title: Nanoscale confinement in carbon nanotubes encapsulated zero valent iron for phenolics degradation by heterogeneous Fenton: Spatial effect and structure activity relationship
year: 2021

abstract: This paper reported a novel ozone catalyst capable of working on acidic solution environments (labeled as CNTs Fe0) which was prepared by immobilizing zero valent iron particles onto the surface of multi walled carbon nanotubes. The catalytic effect of CNTs Fe0 during ozonation was studied in terms of, degradation of methylene blue as model compound and concentration profile of hydroxyl radicals (HO* At pH 3, the production of HO* was sharply accelerated in the presence of CNTs Fe0 about 80 times compared to that obtained by plain ozone, resulting in the intensification of mineralization that was considered to occur mainly in the liquid bulk. In addition to the direct catalytic pathway, a carbon surface mediated Fenton like pathway possibly took place as another important route accounting for the catalytic activity of CNTs Fe0. The role of CNTs substrate during ozonation was evaluated, and it would act as an effective "promoter" rather than ozone catalyst for acidic pH around 3 where CNTs Fe0 optimally works.
author_names: Shuo Zhang

Dong Wang

Xingwen Zhang

Pingping Fan
title: Zero Valent Iron Immobilized on Multi Walled Carbon Nanotubes for Heterogeneous Catalytic Ozonation of Methylene Blue as Model Compound
year: 2014