Impregnation Of Iron Research Articles

Preparation of highly adsorptive biochar by sequential iron impregnation under refluxing and pyrolysis at low temperature for removal of tetracycline

Iron-doping modification is a prevailing approach for improving adsorption capability of biochar with environmental friendliness, but usually requires high temperature and suffers from iron aggregation. Herein, a highly adsorptive biochar was manufactured via sequential disperse impregnation of iron by refluxing and pyrolysis at low temperature for eliminating tetracycline (TC) from aqueous solution. Iron oxides and hydroxides were impregnated and stably dispersed on the carbon matrix as pyrolyzed at 200 °C, meanwhile abundant oxygen and nitrogen functional groups were generated on surface. The iron-doped biochar exhibited up to 891.37 mg/g adsorption capacity at pH 5, and could be recycled with high adsorption capability. The adsorption of TC should be mostly contributed to the hydrogen bonding of N/O functional groups and the hydrogen bonding/coordination of iron oxides/hydroxides. This would provide a valuable guide for dispersedly doping iron and conserving functional groups on biochar, and a super iron-doped biochar was prepared with superior recyclability.

Olive mill waste bio-based catalyst application in advanced oxidation processes for wastewater treatment

This study explores the physicochemical capacities of solid wastes from olive oil mills (olive stone, OS, and olive pomace, OP), in obtaining catalysts to be applied in heterogeneous Fenton and persulfate processes. Through physicochemical treatments and the impregnation of iron by hydrothermal deposition and wetness impregnation (WI) different catalysts were produced, tested and characterized. The olive mill wastewater (OMW) studied in this work is a synthetic solution with five phenolic compounds to mimic the real effluent. The removal efficiency of phenolic acids and organic load (COD) present in this type of effluent was evaluated. In the treatment of synthetic wastewater, almost 100% COD was removed using OS and OP-FeWI as catalysts in the heterogeneous Fenton process. In the sulfate radical-based reaction, the 3,4–Dihydroxybenzoic acid was slightly more degradable than other phenolic acids which confirms the selectivity of sulfate radicals. The materials subject to thermal processes revealed an interesting adsorption capacity. This procedure not only reduces the environmental impact of OMW, but also promotes the implementation of new circular economy approaches.

Silica-supported Fe/Fe\u2013O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives

The hydrogenation of nitriles to amines represents an important and frequently used industrial process due to the broad applicability of the resulting products in chemistry and life sciences. Despite the existing portfolio of catalysts reported for the hydrogenation of nitriles, the development of iron-based heterogeneous catalysts for this process is still a challenge. Here, we show that the impregnation and pyrolysis of iron(II) acetate on commercial silica produces a reusable Fe/Fe–O@SiO2 catalyst with a well-defined structure comprising the fayalite phase at the Si–Fe interface and α-Fe nanoparticles, covered by an ultrathin amorphous iron(III) oxide layer, growing from the silica matrix. These Fe/Fe–O core–shell nanoparticles, in the presence of catalytic amounts of aluminium additives, promote the hydrogenation of all kinds of nitriles, including structurally challenging and functionally diverse aromatic, heterocyclic, aliphatic and fatty nitriles, to produce primary amines under scalable and industrially viable conditions.

A comprehensive study to understand removal efficiency for Cr6+ using magnetic and activated biochar through response surface methodology

This study highlights the advantageous effect of magnetic biochar (MLC) over conventional activated biochar (ALC) used for chromium adsorption from the aqueous solution. The synthesis of MLC was done using an invasive noxious weed “Lantana camara” with impregnation of iron chloride (FeCl3) on biochar surface at 25 °C. The optimum process parameters such as pH (3.01), adsorbent concentration (1.82 g/L), and adsorbate amount (161.23 mg/L) for the maximum chromium adsorption have been calculated using response surface methodology coupled with central composite design. Successful impregnation of iron on biochar with pre and post adsorption analysis has been confirmed using various characterization techniques viz. vibrating sample magnetometry (VSM), field emission scanning electron microscope (FESEM-EDX), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). Among various adsorption isotherms studied, Langmuir isotherm best fits the pseudo-second-order kinetic model for analysis of actual adsorption behavior of Cr6+ ions on ALC and MLC surfaces. Biochar MLC exhibited the maximum chromium adsorption capacity of 102.03 mg/g as compared to low chromium adsorption of 94.69 mg/g using conventional ALC biochar.

A holistic approach for melanoidin removal via Fe-impregnated activated carbon prepared from Mangifera indica leaves biomass

Melanoidins are dark brown coloured complex amino‑carbonyl biopolymer comprising the chief component present in the distillery wastewater with high organic load. In this study, melanoidin removal from a simulated wastewater system was examined via Fe-impregnated activated carbon. Initially, three different leaf-waste biomass (Ficus benghalensis, Ficus religiosa and Mangifera indica) were utilized for preparing the activated carbon followed by impregnation of iron. Further, these prepared activated carbons were characterized via SEM equipped with EDX, XRD, FTIR, and BET analyses. A Box-Behnken design of experiments was employed for evaluating the effect of various parameters onto the melanoidin removal. With the adsorbent dose (62.5 mg/L), initial melanoidin concentration (550 mg/L), temperature (40 °C) and contact time (75 min) and Fe-adsorbent ratio (30%), the maximum melanoidin removal (85.6%) was achieved from waste leaf biomass of M. indica, depicting its potential for the melanoidin removal from wastewater.

Removal of phosphate and aluminum from water in single and binary systems using iron-modified carbons

The simultaneous removal of phosphate and aluminum from water was studied on iron-modified activated carbons. Methods such as oxidation with HNO3, impregnation and co-precipitation of iron were used to modify a commercial coconut activated carbon and to obtain seven different modified carbons. The physicochemical properties of selected samples were studied by different analytic methods such as FT-IR spectroscopy, SEM/EDX analysis and X-ray diffraction. Adsorption studies of phosphate and aluminum from water in single and binary systems were performed in bath systems with constant agitation at 30 °C and different values of pH. Particularly, the sample obtained by Oxidation-Impregnation-Drying procedure (CCOFeTB) contains 3.80% of iron in amorphous phase according to the EDX and XRD analysis, respectively. Additionally, this sample showed the best adsorption performance achieving an adsorbed amount of phosphates of 23.33 mg/g at pH 2 in single system. In binary systems, it was observed a synergistic effect in the adsorption of both species (phosphate and aluminum) and the principal adsorption mechanism is related to electrostatic interactions according with the results of molecular simulation.

Equilibrium, kinetic and thermodynamic studies of removal of phenol from aqueous solution using surface engineered chemistry

Iron impregnated activated carbon has been used as a new adsorbent for the adsorptive removal of phenol from waste water. Impregnation of iron was confirmed by Fourier transform infrared spectroscopy and scanning electron microscope and energy dispersive spectroscopy. Different parameters affecting the adsorption capacity of Iron impregnated activated carbon such as Iron impregnated activated carbon dosage, contact time, pH of solution, initial concentration of phenol and agitation speed were optimized. The residual concentration of phenol was determined by UV-Vis spectroscopy. Maximum adsorption efficiency was calculated 98.5% at optimized parameters: concentration of phenol 25 mg L−1, Iron impregnated activated carbon dose 75 mg, pH 7.0 and agitation time 90 min. The experimental data was fitted to different adsorption isotherms and adsorption capacities obtained were 20 and 15 mg g−1, respectively. Adsorption energy was found to be 1.54 kJ mol−1 which predicts that phenol was adsorbed onto the Iron impregnated activated carbon through physisorption.

A cost-effective approach for abatement of cyanide using iron-impregnated activated carbon: kinetic and equilibrium study

The present study is devoted for eliminating cyanide from wastewater through adsorption onto a surface impregnated with iron. It is seen that the impregnation of iron improves the removal efficacy of cyanide. Ferric nitrate nonahydrate has been used as impregnating agent, and Corncob, a waste material, has been used as a progenitor for the preparation of adsorbent. For determining the optimum conditions for impregnation of iron, response surface methodology has been employed. Combined effect of weight ratio, time, and temperature has been tested, and optimum condition has been obtained with weight ratio (1.0), time (1.50 h), and temperature (400 °C), and the sample made at this condition is named as iron-impregnated activated carbon (IIAC). While studying the adsorptive behavior of IIAC in contrast to activated Corncob without impregnation (ACWI), it has been found that for a cyanide solution of 50 mg L−1, ACWI can remove only 61% of cyanide and IIAC is able to remove around 91% at a constant adsorbent dosage of 10 g L−1. The minimum (− 1) and maximum (+ 1) level of particle sizes (45–150 µm), adsorbent dosage (5–20 g L−1), and initial concentration (IC) of cyanide (5–50 mg L−1) on cyanide removal have been examined using ANOVA, at room temperature (25 °C) for knowing the dependence on the same. Maximum cyanide removal (99.58%) has been achieved at an optimum particle size of 100 µm, adsorbent dosage of 3.95 g L−1, IC of 27.5 mg L−1 at pH 7.5 with IIAC. Langmuir and Freundlich isotherm models have been used for analyzing equilibrium data where Freundlich isotherm has been suitable. Different kinetic models have been employed to fit the data. Pseudo-second-order kinetic model has been found to be most applicable.

Degradation of phenol by heterogeneous Fenton process in an impinging streams reactor with catalyst bed

AbstractIn the present study, the decomposition of phenol in aqueous solutions was investigated in both impinging system and batch reactor. In impinging reactor, catalyst particles with an average diameter of 1.5 × 103μm were confined in a wired cage located in the middle of the reaction vessel. The catalyst was synthesized by impregnation of iron on clinoptilolite zeolite as the support. The mean residence time of the solution in this reactor was 3 s. Therefore, the number of impingements required for the complete degradation of phenol was assessed to be 8 times. The advantage of performing the impinging reactor over a conventional reaction system has been demonstrated in this study. In the impinging reactor at 55 °C, time needed for degradation of phenol in aqueous media was measured to be as low as 24 s; however, phenol degraded completely in 10 min in batch stirred reactor. The optimum operating conditions for the impinging reactor were found as: catalyst containing 5 wt% iron, pH = 3.25, weight ratio of H2O2/phenol = 20, temperature = 55 °C. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Fe-containing carbon obtained from ferrocene: Influence of the preparation procedure on the catalytic performance in FTS reaction

Four different preparation routes were applied to obtain Fe-containing carbon catalysts for Fischer Tropsch Synthesis (FTS) including copolymer assisted co-precipitation of iron precursor, chemical modification of ferrocene, sol-gel and wetness impregnation of iron on polymeric carbon. The effects of the FTS reaction temperature and pressure were also examined. Using ferrocene as a starting precursor and applying sol-gel method to prepare the solid, the syngas is readily converted to C10+ hydrocarbons with a conversion of up to 56% and a productivity of 34mg hydrocarbon.gcat−1.h−1 at 240°C and 20atm. Impregnation method gave a Fe/C based catalyst with the highest exposure of active sites, including surface Fe3+ and Fe2+ redox sites with great properties in FTS. Chemical modification of ferrocene route enables the formation of hematite and maghemite nanoparticles on carbon, which were in situ reduced to magnetite and iron carbides, being the latter mostly active for the water gas shift reaction. It is found that copolymer assisted co-precipitation of ferrocene facilitates the production of large crystals of magnetite, which suffered from sintering and coking exhibiting low performance in FTS. Among these methods, sol-gel based catalyst proved to have superior performance due to the good dispersion of Fe, stable magnetite and iron carbide and Fe-doped nitrogen carbon phases production. Based on spent catalysts characterizations, the synergetic effect between magnetite and the iron carbides phases in the sol-gel based catalyst plays an important role in heavy hydrocarbon formation.

Cu and Fe oxides dispersed on SBA-15: A Fenton type bimetallic catalyst for N,N-diethyl-p-phenyl diamine degradation

A bimetallic oxidation catalyst has been synthesized via wet impregnation of copper and iron over a mesoporous SBA-15 silica support. Physicochemical properties of the resulting material were characterized by XRD, N2 physisorption, DRUVS, FTIR, Raman, SEM and HRTEM, revealing the structural integrity of the parent SBA-15, and presence of highly dispersed Cu and Fe species present as CuO and Fe2O3. The CuFe/SBA-15 bimetallic catalyst was subsequently utilized for the oxidative degradation of N,N-diethyl-p-phenyl diamine (DPD) employing a H2O2 oxidant in aqueous solution.

Simultaneous Adsorption of Cr(VI) and Phenol from Binary Mixture Using Iron Incorporated Rice Husk: Insight to Multicomponent Equilibrium Isotherm

Fe modified rice husk was prepared as a low cost biosorbent for the removal of Cr(VI) and phenol both singly and in combination from single and binary simulated synthetic waste water. Rice husk was modified by treating with FeSO4·7H2O. The results showed that impregnation of iron onto the surface of rice husk improved the adsorption capability of both Cr(VI) and phenol. The effects of process parameters for multicomponent system such as pH, adsorbent dose, and contact time onto the percentage removal of both Cr(VI) and phenol were investigated. The experimental data for the adsorption of both Cr(VI) and phenol onto the surface of Fe modified rice husk applied to various kinetic and adsorption isotherm models. Multicomponent isotherm models such as Nonmodified Langmuir, Modified Langmuir, Extended Langmuir, Extended Freundlich, Competitive Nonmodified Redlich Peterson, Competitive Modified Redlich Peterson were applied. The results show that Extended Freundlich model best described the experimental data for both Cr(VI) and phenol from binary solution. Pseudo second-order model agreed well with Cr(VI) while pseudo first-order model agreed well with phenol. Maximum adsorption capacity in synthetic binary solution of Cr(VI) and phenol was found to be 36.3817 mg g−1for Cr(VI) and 6.569 mg g−1for phenol, respectively.

Synthesis and characteristics of magnesium inserted on porous silica materials by mechanical alloying

Impregnation of nanocrystalline magnesium and iron at different concentrations into Beta zeolite was studied employing two techniques: the Traditional Method (TM) and Mechanical Milling (MM). It is known that hydrogen is a potential fuel for the development of the society in a friendly environment with the world; however, there are great challenges for storage. Hydrides of metals are considered as a promising alternative in the areas of materials and energy. Both techniques employed in this study allowed the distribution of Mg and Fe metals in the porous of the Beta zeolite support, high surface area values and a promising adsorption capacity of hydrogen. Therefore, zeolites appeared as materials of interest in the field of alternative energy. The efficiency of impregnation of both techniques was evaluated and the samples were characterized by appropriate methods.

Synthesis of a Fe–Ni Alloy on a Ceria Support as a Noble‐Metal‐Free Catalyst for Hydrogen Production from Chemical Hydrogen Storage Materials

AbstractBimetallic FeNi nanoparticles supported on CeO2 was proven to be effective for hydrogen production from ammonia–borane (NH3–BH3) as a noble‐metal‐free catalyst. Impregnation of iron and nickel ions with the CeO2 surface followed by in situ reduction with NaBH4 prior to catalytic dehydrogenation of AB produced highly dispersed and partially oxidized amorphous FeNi NPs stabilized by strong interaction with the CeO2 support by NiOCe and FeOCe bonding. Investigation of the influence of the Fe/Ni ratio revealed a volcano‐shaped relationship with a maximum at Fe/Ni=1. FeNi/CeO2 was further applicable to dehydrogenation from dimethylamine–borane ((CH3)2NHBH3). The advantages of this catalytic system, such as the facile preparation method, free of noble metals, and high recyclability, with easy recovery from the reaction mixture by application of an external magnet, are particularly desirable for a hydrogen vector in terms of potential industrial application in fuel cells.

Kinetic determination of a highly reactive impregnated Fe2O3/Al2O3 oxygen carrier for use in gas-fueled Chemical Looping Combustion

Abstract The objective of this work was to determine the kinetic parameters for reduction and oxidation reactions of a highly reactive Fe-based oxygen carrier for use in Chemical Looping Combustion (CLC) of gaseous fuels containing CH 4 , CO and/or H 2 , e.g. natural gas, syngas and PSA-off gas. The oxygen carrier was prepared by impregnation of iron on alumina. The effect of both the temperature and gas concentration was analyzed in a thermogravimetric analyzer (TGA). The grain model with uniform conversion in the particle and reaction in grains following the shrinking core model (SCM) was used for kinetics determination. It was assumed that the reduction reactions were controlled by two different resistances: the reaction rate was controlled by chemical reaction in a first step, whereas the mechanism that controlled the reactions at higher conversion values was diffusion through the product layer around the grains. Furthermore, it was found that the reduction reaction mechanism was based on the interaction of Fe 2 O 3 with Al 2 O 3 in presence of the reacting gases to form FeAl 2 O 4 as the only stable Fe-based phase. The reaction order values found for the reducing gases were 0.25, 0.3 and 0.6 for CH 4 , H 2 and CO, respectively, and the activation energy took values of between 8 kJ mol −1 (for H 2 ) and 66 kJ mol −1 (for CH 4 ). With regard to oxidation kinetics, the reacting model assumed a reaction rate that was only controlled by chemical reaction. Values of 0.9 and 23 kJ mol −1 were found for reaction order and activation energy, respectively. Finally, the solids inventory needed in a CLC system was also estimated by considering kinetic parameters. The total solids inventory in the CLC unit took a minimum value of 150 kg MW −1 for CH 4 combustion, which is a low value when compared to those of other Fe-based materials found in the literature.

Iron-impregnated activated carbons precursor to rice hulls and areca nut waste in the remediation of Cu(II) and Pb(II) contaminated waters: a physico-chemical studies

The aim of this study is to exploit the abundantly available rice hulls and areca nut waste in obtaining the activated carbons which is further impregnated with a low dose of iron to obtain the iron-impregnated activated carbon (IIAC) samples. The solids are characterized by the IR and XRD analytical tools whereas the surface morphology is discussed with the SEM images of these solids. BET specific surface area which was obtained for these materials showed that the impregnation of iron did not significantly affect the specific surface area of these solids. Further, the materials were employed in the removal of two different heavy metal toxic ions viz. Cu(II) and Pb(II) under the batch and column reactor operations. The batch data were collected for various physico-chemical parametric studies, viz. effect of solution pH, sorptive concentration, contact time, electrolyte concentrations, etc. The mechanism involved at solid/solution interface was discussed with the help of these studies. Moreover, the equilibrium state sorption data and the time dependence data were utilized to conduct the adsorption isotherm and kinetic modeling studies, respectively. The pseudo-second-rate equation was fitted well to the sorption of these two cations; hence, the sorption capacity was estimated to be 1.770 and 1.926 mg/g (for Cu(II)) and 3.507 and 3.439 mg/g (for Pb(II)), respectively for IIAC-R and IIAC-N. The removal of these two cations was also performed under the dynamic experimentations under column studies. The column data were utilized obtaining the breakthrough curves and hence the breakthrough volumes were obtained. Further, the breakthrough data were utilized to simulate it with Thomas equation and, hence, the loading capacity of the columns was estimated to be 2.746 and 3.057 mg/g (for Cu(II)) and 6.957 and 6.505 mg/g (for Pb(II)), respectively for IIAC-R and IIAC-N samples.

A novel CuFe-based catalyst for the oxygen reduction reaction in alkaline media

The primary objective of this work is to develop alternative electrocatalysts to Pt-based materials for the oxygen reduction reaction (ORR) in alkaline fuel cells. We synthesized a bicore CuFe/C composite electrocatalyst by impregnation of iron and copper phthalocyanine-based complexes into a carbon support, followed by pyrolysis at 800–900 °C in an Ar atmosphere. This novel composite catalyst exhibits electrochemical performance for ORR in 0.1 M KOH similar to a commercial Pt/C (BASF Fuel Cell, 30%) catalyst at 6-fold lower CuFe loading. High resolution X-ray photoelectron spectroscopy (HR-XPS) results indicate that coordination bonding between Fe and N atoms still remains and show that a mixed Cu(I)/Cu(II) valency exists in the CuFe/C catalyst after high temperature heat treatment. The Cu(I)/Cu(II) redox mediator adjacent to Fe atoms is crucial to provide electrons to the N xFe–O 2 adduct and maximize the overall rate of the reduction reaction. The results of this study may offer a new approach to development of efficient catalysts for oxygen reduction to water in alkaline media.

Nitrogen-doped graphene nanosheet-supported non-precious iron nitride nanoparticles as an efficient electrocatalyst for oxygen reduction

Nitrogen-doped graphene-supported carbon-containing iron nitride (FeCN/NG) was synthesized by the chemical impregnation of iron and nitrogen-containing precursors in the presence of ammonia under thermal treatment. The resultant graphene-based material acted as an electrode with a much higher electrocatalytic activity in the catalysis via a 4-electron pathway in fuel cells. The results of X-ray diffraction, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy indicated that graphite oxide was successfully reduced to nitrogen-doped graphene. X-Ray absorption spectroscopy further confirmed that carbon was incorporated into iron nitride, demonstrating that Fe–N–C catalytic active sites may be responsible for the oxygen reduction reaction. To the best of our knowledge, this is the first report of the combination of N-doped graphene with non-precious metal for oxygen reduction in fuel cells, and may open up a new possibility for preparing graphene-based nanoassemblies for intensive applications.

Adsorption of arsenic in aqueous solution by RH-Fe-MCM-41

RH-Fe-MCM-41 adsorption efficiency and capacity were examined with arsenic in lower concentrations in aqueous solution under varying pH values. The adsorption of arsenite (As3 + ) and arsenate (As5 + ) by RH-Fe-MCM-41 at the molar ratio of Si/Fe 10 gave removal efficiencies of 47% and 99% for As3 + and As5 + , respectively, in the 100–1,000 μg l−1 concentration range. For the adsorption test of arsenic the best conditions were found to be an equilibrium time of 12 h at pH 7 for As3 + and 2 h at pH 4 for As5 + . The adsorption capacity by the Langmuir constants (Qm) for As3 + and As5 + were 416.67 μg g−1 and 277.78 μg g−1, respectively, while the Freundlich constants (KF) were 0.583 μg g−1 for As3 + and 112.87 μg g−1 for As5 + . The fit for As5 + was good with both the Langmuir and Freundlich isotherms by considering the R2 values, which were quite similar (0.916 and 0.912); As3 + fit well only with the Langmuir isotherm. The impregnation of iron (Fe3 + ) into the RH-Fe-MCM-41 structure increases the adsorption capacity of As3 + and As5 + both by oxidizing As3 + to As5 + and by co-precipitation with As5 + .

Iron impregnation on the amorphous shell of vapor grown carbon fibers and the catalytic growth of secondary nanofibers

Vapor grown carbon fibers (VGCFs) with diameters of several microns were synthesized and investigated by high resolution transmission electron microscopy. It was found that the shell of the VGCFs consisted of densely-packed domains embedded in loosely-packed matrix, and both were highly amorphous. Regular edge planes as observed on the surface of fishbone nanofibers do not exist on VGCFs. Hence, surface treatment is more important for the deposition of catalysts. Ammonium ferric citrate (AFC) was employed for the impregnation of iron, where the high viscosity of the aqueous solution of AFC is beneficial. Calcination was found to be a key step to improve the dispersion of the iron particles, which can be attributed to enhanced interactions between iron and carbon due to the gasification of carbon occurring at the iron–carbon interface. Quantitative analysis by X-ray photoelectron spectroscopy showed that the calcination of the supported AFC led to a higher atomic concentration of iron on the surface, indicating smaller particle size and a higher dispersion. Secondary carbon nanofibers were grown subsequently on the VGCFs from cyclohexane. The specific surface area was enhanced considerably, from less than 1 m 2 g − 1 to 106 m 2 g − 1 after the growth of the secondary nanofibers. The obtained composites are promising materials as structured support in heterogeneous catalysis.