Metallic Iron Nanoparticles Research Articles

Green synthesis of carbon nanotubes impregnated with metallic nanoparticles: Characterization and application in glyphosate adsorption

In the present work, multi-walled carbon nanotubes (MWCNTs) were used as support material for the impregnation of metallic nanoparticles (MNPs) produced by green synthesis. The influences of the plant extracts (pomegranate (Punica Granatum), Eucalyptus, and pecan (Carya illinoinensis, leaves), metal species (copper and iron), metallic concentrations, and type of functionalization (OH and COOH) on the characteristics of the obtained materials were studied. The precursor and impregnated MWCNTs were characterized through X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, point of charge, N2 adsorption/desorption isotherms and, X-ray photoelectron spectroscopy. All the synthesized materials were tested as adsorbents to remove glyphosate (GLY) in an aqueous medium. The MWCNTs were resistant to withstand the synthesis process, preserving its structure and morphological characteristics. The copper and iron on the surface of MWCNTS confirm the successful synthesis and impregnation of the MNPs. The MWCNTs impregnated with high metallic concentrations showed favorable adsorption of GLY. The adsorption capacity and percentage of removal were 21.17 mg g−1 and 84.08%, respectively, for the MWCNTs impregnated with iron MNPs using the pecan leaves as a reducing agent. The results indicated that an advanced adsorbent for GLY could be obtained by green synthesis, using MWCNTs as precursors and pecan leaves as a reducing agent.

Coupling Zero-Valent Iron and Fenton processes for degrading sulfamethazine, sulfathiazole, and norfloxacin

In this study, the degradation of three antibiotics — sulfamethazine (SMT), sulfathiazole (STZ), and norfloxacin (NOR) (1.0 mg L–1 each) — was achieved by coupling the Zero-Valent Iron Process using supported metallic iron nanoparticles (nZVI) to the Fenton one. The system was operated in single-pass continuous-flow mode at steady-state regime (after 15 min). The nanoparticles were packed into a fixed-bed reactor and characterized by several techniques (SEM, EDX, TEM, and XRD). The degradation experiments were performed according to a 22 factorial design, in which the effects of pH and flow rate (Q) were studied. The degradation conditions were: initial pH = 3.0 and Q = 20 mL min–1· H2O2 was then continuously added to the effluent of the nZVI reactor (containing Fe2+) in order to perform the Fenton process in the following mixing vessel (H2O2 concentration of 34 mg L–1). At the exit of the system, the antibiotics concentrations were below the detection limit of the chromatographic method (40 µg L–1) and dissolved iron was below 1.0 mg L–1. Sixteen degradation products (DPs) of SMT, STZ, and NOR were detected and identified using HPLC-MS/MS. Their ecotoxicological endpoints (LC50, EC50, and ChV) for three trophic levels were estimated with the aid of the ECOSAR 2.0 software. No ecotoxicity was generated towards Lactuca sativa during treatment. The proposed system was able to partially remove the antimicrobial activity (Escherichia coli) of both sulfonamides (16%) and NOR (47%).

The Effect of Synthesis Parameters on the Size, Composition, and Stability of Iron Nanoparticles

Magnetic nanoparticles (MNPs) have many uses for biomedical applications including drug delivery, magnetic resonance imaging (MRI) contrast agents, theranostics and hyperthermia. MNPs photo-thermally heated by laser light could be used to treat the typically difficult to access tumors such as glioblastomas. Due to their high magnetic saturation, monometallic iron nanoparticles would have an edge over iron oxide nanoparticles currently being investigated for hyperthermia. The goal of this study was to synthesize spherical iron nanoparticles less than 10 nm in diameter by thermal decomposition. The ability of various biocompatible coatings to protect the metallic iron nanoparticles from oxidation was investigated. Coatings studied included Brij, polyethylene glycol and iron oxide. Transmission electron microscopy and Mössbauer spectroscopy were utilized to characterize the coated and uncoated iron nanoparticles’ size and oxidation state to evaluate the effectiveness of the coatings and the procedures in which the coatings were applied. A ferrite shell was found to provide the best stabilization; however, its longer synthesis time increased particle size distribution. Polymer coatings provided biocompatibility but did not prevent oxidation.

MOF derived novel zero-valent iron @ graphitic carbon-based nanoreactors for selective reduction of hazardous 4-nitrophenol

Fabrication of stable and efficient zerovalent non-noble metal-based nanostructured catalyst has emerged as the hot area of research for wastewater treatment due to their low cost and facile natural source availability. In this work, the rationally controlled calcination of iron-terephthalate MOF has produced the magnetically active zero-valent iron-based nanostructured catalyst. Unlike other synthesis approaches, MOF’s temperature-controlled calcination has offered highly effective and stable metallic iron nanoparticles encapsulated in few-layered porous graphitic carbons. The developed nanostructured catalyst was applied for room temperature conversion of hazardous 4-Nitrophenol (4-NiP) to a value-added industrial intermediate 4-Aminophenol (4-AP) by exploiting sodium borohydride as a hydrogen donor agent. The synthesized zerovalent iron-based nanostructured catalysts were thoroughly investigated and characterized by powder X-ray diffraction (pXRD), infrared and Raman spectroscopy, thermogravimetric analysis (TGA), energy dispersive X-Rays (EDS), X-ray photoelectron (XPS) spectroscopy, and transmission electron microscopy (TEM). The UV–Vis spectroscopy was used for the monitoring of the conversion of the 4-NiP into 4-AP. The conversion analysis result has shown that the MOF-based precursors’ calcination temperature has played a critical role in the potency of the catalyst for converting the 4-NiP into 4-AP. The outer porous architecture provided the facile adsorption and desorption of the 4-NiP on the active nanostructured metallic iron catalyst. The maximum degradation of 4-NiP into 4-AP has taken place in a short time of 3 ​min at a rate constant of 0.0149 s −1 . In terms of economic perspective and high catalytic efficiency, the developed low coast nanostructured catalyst is the right choice over the reported noble metal-based catalyst for the room temperature conversion of 4NiP to a value-added product. • Synthesis of MOF derived stable Zero-valent Iron @ Graphitic Carbon-based Nanoreactors. • Room temperature reduction of hazardous water pollutant 4-Nitrophenol. • Conversion of 4-Nitrophenol pollutant to a value-added 4-Aminophenol. • Magnetic iron nanoparticles for selective hydrogenation.

ADVANCES OF NON-IRON METAL NANOPARTICLES IN BIOMEDICINE.

Metal nanoparticles (MNPs) comprise of nanoparticles originating from metallic elements with additional properties inherent to metal ions. MNPs found applications in various field such as electronics, optics, mechanics, physics etc. There are many reviews on iron MNPs for biomedical application. Hence, in this review, we focus on non-iron MNPs and their vivid biomedical applications. Here, we review the applications of non-iron MNPs in biomedicine such as drug delivery, gene delivery, anticancer activity, antimicrobial activity, tissue engineering, bioimaging, and photodynamic, and photothermal therapies.

Eggshell membranes coated chitosan decorated with metal nanoparticles for the catalytic reduction of organic contaminates

This study focusses on the effect of chitosan coating with eggshell membranes for the reduction of different organic pollutants. Chickens eggs were collected from the local market and utilized to extract the enrich eggshell membranes (ESM). The chicken eggshell membranes are abundant waste material which is inexpensive and illustrates remarkable physiognomies for many possible applications. Fresh fibers/strips coated by chitosan (CS) were prepared by mixing the eggshell membranes with CS solution (2 wt%/v) in different proportions i.e., 10 %, 30 %, 50 %, 60 %, 70 %, 80 %, and 90 %. These strips were then templated with copper and iron metal nanoparticles by putting them in their metal ions aqueous solution to adsorb the metals ions and were then reduced to zero-valent metal nanoparticles (MNPS) by using NaBH4 aqueous solution. These prepared materials (MNPS@ESM-CS) were characterized by using XRD, XPS, FE-SEM, and EDS to confirm the successful preparation of MNPs over the surface of ESM coated with CS. Afterwards, these prepared materials were investigated as a catalyst for the reduction of different organic pollutants, such as 4-nitroaniline (4-NA), 4-nitrophenol (4-NP) and methylene blue (MB) dye. The catalytic efficiency of ESM was enhanced 5.7-fold by adding only 20 % CS solution. It was observed that Cu@ESM-CS-80 % took 7 min for reduction of 4-NA, 6 min for 4-NP, and 7 min for MB dye. The reusability of the catalytic strip was also investigated for four cycles and found efficient and can be easily recovered by simply pulling it from the reaction mixture.

Biosynthesis of Copper and Iron Nanoparticles using Neem (Azadirachta indica) Leaf Extract and their Anti-bacterial Activity

Neem leaves extract was use to synthesize metal (iron and copper) nanoparticles. The nanoparticles were characterized using Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) and UV-Vis spectrometer. The formation and stability of the reduced metal nanoparticles in the colloidal solution were monitored by UV–Vis spectrophotometer analysis. Their peaks of CuNPs and FeNPs were determined with a particles size in the range of 250nm-550nm and 250nm-350nm and have shapes of spherical and dendrimer respectively. The zone of inhibition by CuNP on gram negative bacteria (Staphylococcus Aureus) is 20mm ± 1 while on gram positive bacteria (Escherichia Coli) is 12.5mm ± 1. Thus, the synthesized metal nanoparticles prove to have very high anti-bacterial activity on both Staphylococci aureus and Escherichia coli. Copper nanoparticles exhibits high antibacterial activity compared to iron nanoparticles.
 Keywords: Copper, Iron, nanoparticles, Anti-bacterial activity

Combined production of metallic-iron nanoparticles: exergy and energy analysis of two alternative processes using Hydrazine and NaBH4 as reducing agents

This study deals with the simulation of two alternative processes for the coupled production of metallic iron nanoparticles and the necessary reducing agent: hydrated hydrazine and sodium borohydride. After carrying out a sensitivity analysis to identify the optimal operating conditions for each process, the results have been interpreted in the light of energy and exergy analysis. The study demonstrated that the sodium borohydride-based iron nanoparticles production is more profitable than the hydrazine-based one, because of a higher exergy efficiency as a consequence of lower exergy destruction value. The total heat duty required for the borohydride-based process was only 1.1 MWh with respect to 5 MWh for the hydrazine-based one. Conversely, cooling water and total power consumptions for the latter process are significantly lower than for the former one (2.33 t/h versus 26.87 t/h, and 2 kWh versus 88.7 kWh, respectively). Furthermore, as reported in the literature, the hydrazine-based process allows to produce high purity iron nanoparticles, since hydrazine is transformed completely in N2 during the process. Both processes were designed to produce 1765 kg/d of iron and the same amount of produced reducing agent was also stored as secondary product of the plant.

Combination of immobilized TiO2 and zero valent iron for efficient arsenic removal in aqueous solutions

The photocatalytic removal of arsenic from aqueous solutions was investigated using titania (TiO2) immobilized on a glass support, both bare and combined with synthesized metallic iron nanoparticles (nZVI) or commercial microscale iron (ZVI). Three procedures, namely dip-coating, rotational coating, and sponge coating, were tested for achieving the immobilization of TiO2. The photocatalytic activity of the semiconductor films under UV-irradiation after cumulative coatings was evaluated for 10 mg L−1 aqueous As(III), which was entirely oxidized to As(V) with all settings within 90 and 180 min. Titania immobilized by dip-coating was found to be the most effective as it showed the faster kinetics. The reuse of immobilized TiO2 was also investigated, detecting no changes in the photocatalytic activity after five consecutive reactions. The addition of commercial ZVI particles to the immobilized TiO2 system did not bring about significant changes in the kinetics for As(III) oxidation at the three pH values investigated, i.e., 5, 7, and 9. By contrast, the addition of nZVI not only led to a faster depletion of As(III) compared to bare titania but also the removal of As(V) from the solution to concentrations below 10 μg L−1, the upper limit recommended by the World Health Organization for human consumption.The role of iron species in the arsenic removal process with both [ZVI + immobilized-TiO2] and [nZVI + immobilized-TiO2] systems was further investigated by performing adsorption and irradiation experiments without titania. It was inferred that within the pH range evaluated, the minor corrosion of the ZVI surface, even under UV irradiation, restricts the production of reactive oxidizing species and the generation of sites for arsenic species adsorption. By contrast, adsorption should be the main process responsible for the overall diminution of As(III) and As(V) species in solution attained upon nZVI addition, promoted by the increase of the external oxides/hydroxides layer on iron nanoparticles. Nevertheless, it might be also considered a certain contribution of UV-generated oxidant species formed in nZVI to the photocatalytic oxidation performance of titania.

Understanding the dehydrogenation mechanism over iron nanoparticles catalysts based on density functional theory

The conversion of chemical feedstock materials into high value-added products accompanied with dehydrogenation is of great value in the chemical industry. However, the catalytic dehydrogenation reaction is inhibited by a limited number of expensive noble metal catalysts and lacks understanding of dehydrogenation mechanism. Here, we report the use of heterogeneous non-noble metal iron nanoparticles (NPs) incorporated mesoporous nitrogen-doped carbon to investigate the dehydrogenation mechanism based on experiment observation and density functional theory (DFT) method. Fe NPs catalyst displays excellent performance in the dehydrogenation of 1,2,3,4-tetrahydroquinoline (THQ) with 100% selectivity and 100% conversion for 10−12 h at room temperature. The calculated adsorption energy implies that THQ prefers to adsorb on Fe NPs as compared with absence of Fe NPs. What is more, the energy barrier of transition state is relatively low, illustrating the dehydrogenation is feasible. This work provides an atomic scale mechanism guidance for the catalytic dehydrogenation reaction and points out the direction for the design of new catalysts.

Biomass-derived ultrathin carbon-shell coated iron nanoparticles as high-performance tri-functional HER, ORR and Fenton-like catalysts

The development of cost-effective carbon-shell coated metal-based nanocatalysts is currently a highly desirable goal towards the fabrication of more sustainable non-precious nanocatalysts. Herein, we design an easy, cheap, scalable, and eco-friendly carbothermal reduction strategy to develop core-shell structured metallic iron nanoparticles using coffee waste grounds as starting renewable materials (Fe@BMC). The structural properties of the as-synthesized nanoparticles were nicely tuned by varying the reaction temperature. Remarkably, ultrathin carbon-shell coated metallic iron nanoparticles were obtained at 800 °C, which was clearly elucidated by the HRTEM, XRD, and XPS measurements. The Fe-800 °C@BMC nanocatalyst showed excellent properties as an ORR electrocatalyst with an onset potential of 0.93 V vs RHE, keeping 90% of the initial current applied after the 20000s. Noticeably, the Fe-800 °C@BMC carbon-shell nanostructures delivered a Pt-like performance with a very low onset potential of −25 mV vs RHE, an overpotential of 75 mV at a current density of 10 mA cm−2 and an ultrahigh stability to keep the 99% of the initial current applied after 20000s, behaving like one of the most efficient HER core-shell structured non-precious electrocatalysts reported up to now. Also, the Fenton like catalytic studies revealed that the Fe-800 °C@BMC nanocatalyst was so far the most active catalyst for the degradation of tetracycline (TC) antibiotic allowing the degradation of 95.72% of TC in 45 min with a higher reaction rate constant of 0.068 min−1. The impressive catalytic behavior of the Fe-800 °C@BMC nanocatalyst was attributed to the hierarchically porous carbon network as well as to the synergistic interaction between the encapsulated metallic iron core and the ultrathin carbon shell, which regulate the adsorption energy of the reactive species. The present work offers new insights into the development of scalable and high-performance tri-functional catalysts through a sustainable and low-cost synthetic route.

Regulation of the size of metal iron nanoparticles in channels of mesoporous silica matrices (MCM-41, SBA-15) and structure and magnetic properties of the received nanocomposites МСМ-41/Fe0 and SBA-15/Fe0

In modern methods of synthesis of nanostructured materials based on mesoporous silica matrices (MCM-41, SBA-15), it is not possible to simultaneously fine adjust both the pore diameter and the thickness of the separating walls. This article presents the results of work on the creation of composites based on mesoporous silica matrices MCM-41 and SBA-15, reinforced with metallic Fe nanoparticles (Fe NPs). The article considers a new way of ultrafine regulation of the pore radius and separating wall thickness mesoporous silica SBA-15. In this work, we studied the changes in their structural and magnetic characteristics by directionally adjusting the geometric parameters of the porous structure of the initial matrices. The following methods are applied to adjust the silica pore parameters: hydrothermal treatment and templating using a micellar expander. The technique is based on building up aluminum-oxygen nanolayers on the pore walls using gas-phase atomic layer deposition technique (ALD). Studying room-temperature magnetization of Fe NPs obtained during the synthesis in a matrix of mesoporous silica MCM-41 (pore size of 3–5 nm) allowed us to establish superparamagnetic properties of such magnetic materials, which allows to use them in medicine for targeted drug delivery. Fe NPs in the mesoporous silica SBA-15 matrix with a pore size of 3–6 nm also exhibit superparamagnetic properties, and these composites showed a coercive force increase with an increase in the original matrix pore size.

Stabilizing Metallic Iron Nanoparticles by Conformal Graphitic Carbon Coating for High-Rate Anode in Ni-Fe Batteries.

Nickel-iron (Ni-Fe) batteries are promising candidates for large-scale energy storage due to their high safety and low cost. However, their power density and cycling efficiency remain limited by the poor kinetics of the Fe anode. Herein, we report high-performance Fe anodes based on active Fe nanoparticles conformally coated with carbon shells, which were synthesized from low-cost precursors using a scalable process. Such core-shell structured C-Fe anodes offer high electrochemical activity and stability. Specifically, a high specific capacity of 208 mAh g-1 at a current density of 1 A g-1 (based on the total weight of Fe and C) and a capacity retention of 93% after 2000 cycles at 4 A g-1 can be achieved. When coupled with a Ni cathode, such a full cell battery can deliver a high energy density of 101.0 Wh kg-1 at power density of 0.81 kW kg-1 and 51.6 Wh kg-1 at 8.2 kW kg-1 (based on the mass of the electrode materials), among the best energy and power performance among Ni-Fe batteries reported results. Thus, this work may provide an effective and scalable route toward high-performance anodes for high-power and long-life Ni-Fe batteries.

Production of metallic iron nanoparticles in a baffled stirred tank reactor: Optimization via computational fluid dynamics simulation

The aim of this work is to optimize iron nanoparticle production in stirred tank reactors equipped with two classical impellers: Rushton and four-pitched blade turbines, which are largely used in batch industrial synthesis and efficient scale-up. The main operative parameters of nanoparticle synthesis are the precursor initial concentration, reducing agent/precursor molar ratio, impeller–tank clearance, and impeller rotational velocity. These parameters were varied during the synthesis to find the optimal operating values based on the Fe(0) (%) production, zeta potential, particle size distribution, and powder X-ray diffraction pattern obtained. We found that the optimal operating conditions for nanoparticle production were an impeller velocity of 1500rpm, initial iron precursor concentration of 20mM, molar ratio of reducing agent to iron precursor of 3mol/mol, and impeller clearance of 0.25 and 0.4 times the vessel diameter for Rushton and four-pitched blade impellers, respectively. Setting these conditions achieved a total conversion of 0.94–0.98 and yielded a product with a unimodal size distribution and average diameters in the range 30–50nm. The computational fluid dynamics results agreed with the expectations, and the obtained mixing Damkohler numbers show that the process is mixed controlled.

A short review on green synthesis of iron metal nanoparticles via plants extracts

Nanotechnology been emerged recently of the years as a “state of the art” with multifunction in many applications fields. The broad area of technology nanoparticles including varies of nanomaterials, nanodevice and nanotools as well. Majority of the researcher are mainly focusing upon the nanomaterials which deal with nanoparticles (NPs). Several methods via chemical and physical technique synthesis are well knowns the capability of producing NPs, however, both methods are blocked with the several limitations. Due to this disadvantage, many researchers are shifted to the “green technology” which clean and more eco-friendly to environment. The combination of ability of magnetic and nanoparticles characteristic, gives an important for inorganic nanoparticles which problem solver in many applications in different fields of research. This review is focusing on the green technology of biosynthesis where outlining the novel path.

Graphitic‐Shell Encapsulation of Metal Electrocatalysts for Oxygen Evolution, Oxygen Reduction, and Hydrogen Evolution in Alkaline Solution

AbstractDeveloping highly efficient, cost effective, and environmentally friendly electrocatalysts for the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) is of interest for sustainable and clean energy technologies, including metal–air batteries and fuel cells. In this work, the screening of electrocatalytic activities of a series of single metallic iron, cobalt, and nickel nanoparticles and their binary and ternary alloys encapsulated in a graphitic carbon shell toward the OER, ORR, and HER in alkaline media is reported. Synthesis of these compounds proceeds by a two‐step sol–gel and carbothermal reduction procedure. Various ex situ characterizations show that with harsh electrochemical activation, the graphitic shell undergoes an electrochemical exfoliation. The modified electronic properties of the remaining graphene layers prevent their exfoliation, protect the bulk of the metallic cores, and participate in the electrocatalysis. The amount of near‐surface, higher‐oxidation‐state metals in the as‐prepared samples increases with electrochemical cycling, indicating that some metallic nanoparticles are not adequately encased within the graphite shell. Such surface oxide species provide secondary active sites for the electrocatalytic activities. The Ni–Fe binary system gives the most promising results for the OER, and the Co–Fe binary system shows the most promise for the ORR and HER.

Structural composite supercapacitor using carbon nanotube mat electrodes with interspersed metallic iron nanoparticles

A carbon nanotube (CNT) mat interspersed with metallic iron nanoparticles is investigated as a structural supercapacitor electrode material that could be incorporated into fiber-reinforced composites. Both ionic liquid and aqueous potassium hydroxide electrolytes are trialed to examine pseudocapacitive mechanisms and the long-term electrochemical stability of the CNT mat in symmetrical supercapacitors. High-resolution transmission electron microscopy showed the high level of interconnection of the CNTs and evenly distributed metallic iron nanoparticles, which enhances the structural and electrical performance of the electrode. Raman and X-ray photoelectron spectroscopies combined with thermogravimetric and surface area analyses are used to characterize the physico-chemical properties of the CNT mat and identify the different electrochemical mechanisms contributing to the supercapacitive behavior. Three electrode experiments demonstrated the relative contributions of the cathode and anode processes to the total capacitance. Symmetrical supercapacitor coin-cell trials used a structural glass-fiber separator and showed the ionic liquid electrolyte facilitated stable pseudocapacitance with the available iron nanoparticles, leading to specific energy and power as high as 18.3 Wh.kg−1 at 0.15 kW kg−1 and 5.6 Wh.kg−1 at 2.4 kW kg−1 after 5000 cycles. It is envisioned these materials can readily be incorporated into composite materials for structural energy storage technology.

Avantium obtains funding from EU Horizon 2020

The aim of this work was to investigate the optimization of iron nanoparticles production by spinning disk reactor. The influence of the two main operating parameters, i.e. rotational velocity and feed injection point position was investigated through evaluating the particle size distribution, the X-Ray powder diffraction spectra and metallic iron percentage production. Results showed that increasing both rotational velocity and the distance of reagents injection feed points from the disk centre led, to the production of metallic iron nanoparticles characterized by lower mean size. In particular, the optimal rotational velocity was found to be 1400 rpm whereas the optimal distance of injection feed point from disk centre was found to be 3.5 cm. According to these operating parameter values it was possible to obtain monodisperse nanoparticles, characterized by a mean size of 28 ± 2.1 nm and a production in the range 0.24–24 kg/day depending on the initial Fe(II) concentration. The results were then interpreted in light of three fluid dynamics models able to simulate the rotating thin liquid film on the surface of the spinning disk reactor. The applicability of Nusselt model was also investigated and discussed.

Metallic iron nanoparticles intensified production by spinning disk reactor: Optimization and fluid dynamics modelling

The aim of this work was to investigate the optimization of iron nanoparticles production by spinning disk reactor. The influence of the two main operating parameters, i.e. rotational velocity and feed injection point position was investigated through evaluating the particle size distribution, the X-Ray powder diffraction spectra and metallic iron percentage production. Results showed that increasing both rotational velocity and the distance of reagents injection feed points from the disk centre led, to the production of metallic iron nanoparticles characterized by lower mean size. In particular, the optimal rotational velocity was found to be 1400 rpm whereas the optimal distance of injection feed point from disk centre was found to be 3.5 cm. According to these operating parameter values it was possible to obtain monodisperse nanoparticles, characterized by a mean size of 28 ± 2.1 nm and a production in the range 0.24–24 kg/day depending on the initial Fe(II) concentration. The results were then interpreted in light of three fluid dynamics models able to simulate the rotating thin liquid film on the surface of the spinning disk reactor. The applicability of Nusselt model was also investigated and discussed.

Nitrogen doped carbon supported iron catalysts for highly selective production of 4,4′-diamino-2,2′-stilbenedisulfonic acid

Nitrogen doped carbon supported iron catalysts were prepared from pyrolysis of a multidentate nitrogen ligand iron complex supported on chitosan at different temperature, and showed good performances in the reduction of 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNS acid) to 4,4′-diamino-2,2′-stilbenedisulfonic acid (DSD acid) with hydrazine hydrate (N2H4·H2O) as reductant. Characterization results revealed that the iron is mainly present in the form of Fe2O3 and metallic iron nanoparticles. The doped N atoms functionalized as anchoring sites to stabilize iron nanoparticles, which endows the catalysts with excellent activity and superior reusability.