Role of iron ore in enhancing gasification of iron coke:Structural evolution,influence mechanism and kinetic analysis

The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was investigated.Furthermore,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method.The findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and interconnect.This provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron coke.Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke.The metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon atoms.The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure.Moreover,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.

Comparison of Conventional and Microwave-assisted Synthesis and Characteristics of Aluminum-pillared Rectorite

The synthesis and characterization of aluminum-pillared rectorite were studied. The synthesis was conducted with both conventional heating and microwave irradiation. Microwave irradiation was found to enhance the intercalation and ion-exchange during synthesis, and to be able to produce the rectorite with a larger d_(001) and a better uniformity. The specific surface area is 180 m^2/g and basal spacing is 3.2 nm. The texture change and thermal and hydrothermal stability of cross-linked rectorite were examined using XRD, FTIR, nitrogen-adsorption and TGA. The experimental results show that the aluminum-pillared rectorite, after calcined at 800 ℃ for 3 hours, can keep the basal aluminum-silicate texture and would not disperse in water at room or an elevated temperature. The aluminum-pillared rectorite shows a high specific surface area, good thermal and hydrothermal stability, and is promising in applications as catalyst carriers and adsorbents for waste treatment.

Adsorption of Methylene Blue from Aqueous Solution onto Hydrochloric Acid-modified Rectorite

H＋-rectorite clay,which was prepared by modifying the raw rectorite with 10% hydrochloric acid at 60 °C for 24 h,was used as an absorbent for removal of methyl blue （MB） from aqueous solutions.The morphology and the structure and crystallinity of the pristine rectorite and the H＋-rectorite were characterized by scanning electron microscopy （SEM） technique and X-ray diffraction （XRD） technique,respectively.The results showed that the H＋-rectorite exhibited high adsorption ability than the raw rectorite,and it was found that the removal percentage of MB increased with increasing in adsorbents dose,whereas the adsorption amount qe （mg/g） decreased.The equilibrium was attained within 30 min in adsorption process,and the maximum adsorption capacity of H＋-rectorite for methylene blue reached as high as 37 mg/g.Besides,the effect of temperature on the adsorption of MB with H＋-rectorite was investigated and the equilibrium data were well fitted to Freundlich equations.The H＋-rectorite absorbent saturated with MB can be regenerated by calcinating at 400 °C for 2 h and the regenerated absorbent still showed higher percentage removal of MB.

Morphological Characteristics of (K, Na)-Rectoritefrom Zhongxiang Rectorite Deposit, Hubei, Central China

The morphological characteristics of the Zhongxiang （钟祥） rectorite have been studied using X-ray diffraction （XRD）, electron probe micro-analyzer （EPMA）, scanning electron microscopy （SEM）, atomic force microscope （AFM）, and high-resolution transmission electron microscopy （HRTEM）. The structural formula of the Zhongxiang rectorite is： （Na0.45K0.32Ca0.37Mg0.08）（Al3.78Fe0.11Ti0.10）[（Si6.22Al1.78）O20]（OH）4^＊nH2O. It should be confined to a regular interstratification of （K, Na）-mica and Ca-montmorillonite. SEM observations show that Zhongxiang rectorite occurs as platy and fold-shaped crystals, and mainly as extremely thin plates with thickness ranging from 0.4 to 0.05 μm and a smooth （001） surface. There are well-developed polygonal steps on the surfaces of some thick crystals, suggesting a layer-by-layer growth mechanism. AFM observations show a series of steps with a height of 2 nm on the platy particles, suggesting the stacking of 20 nm fundamental particles. Club-like or fiber-shaped halloysite is included in the platy crystals with their elongated dimension paralleling （001） of the platy crystals or crossing the （001） surface of the platy rectorite, indicating multi-stage crystallization and involvement of hydrothermal fluids. The Zhongxiang rectorite was generated by both layer-by-layer growth mechanism and dissolution and crystallization growth mechanism with multistages.

Synthesis and Characterization of Rectorite/ZnO/TiO2 Composites and Their Properties of Adsorption and Photocatalysis for the Removal of Methylene Blue Dye

As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites（REC/ZnO/TiO2） were synthesized and characterized in this study. Effects of experimental parameters including TiO2 mass ratio, solution p H and catalyst dosage on the removal of methyl blue（MB） were also conducted. The presence of a little mass ratio（2%-6%） of TiO2 highly promoted the photoactivity of REC/ZnO/TiO2 in removal of MB dye from aqueous solution, in which ZnO and REC played a role of photocatalyst and adsorbent. The promotion effects of TiO2 may result from the accelerated separation of electron-hole on ZnO. The observed kinetic constant for the degradation of MB over REC/ZnO and REC/ZnO/TiO2 were 0.015 and 0.038 min^（-1）, respectively. The degradation kinetics of MB dye, which followed the Langmuir–Hinshelwood model, had a reaction constant of 0.17 mg/（L min）. The decrease of removal ratio of MB after five repetitive experiments was small, indicating REC/ZnO/TiO2 has great potential as an effective and stable catalyst.

One-Pot Synthesized Polyurethane-Based Nanocomposites Filled by Original Rectorite with Enhanced Strength and Elongation

The unmodified rectorite（REC）,a kind of layered silicate,was incorporated into polyurethane （PU）as matrix by the process of one-pot synthesizing polyurethane in situ,and hence produced a series of nanocomposite materials with enhanced strength and elongation.It is worth noting that the nanocomposite containing 2 wt%REC had the maximum elongation（1 449%）and strength（32.66 MPa）as ca.2.7-and 1.4-fold over those of neat PU film,respectively.Meanwhile,the unexfoliated agglomerates and exfoliated nanoplatelets of REC co-existed in PU matrix.By virtue of strong interfacial interaction on the surface of REC lamella,the stress facilely transferred to the rigid RECs and hence contributed to the enhancement of strength in spite that the original structure and interaction in the PU matrix were partly cleaved.Moreover,the intertwisting of polymer chains in PU matrix with REC as well as the gliding among the REC lamellae might produce greater strain.Nevertheless,excess unexfoliated REC agglomerates under high loading level inhibited the enhancement of mechanical performances,which verified the key role of exfoliated REC nanoplatelet in improving mechanical performances.As a result,this work submitted a simple method to develop a polyurethane-based nanocomposite with high mechanical performances without any modification of layered silicates and the complicated treatment for exfoliation and dispersion.

Preparation and Structural Characterization of Polystyrene-Rectorite Nanocomposites

The polystyrene/rectorite nanocomposites were prepared by free radical polymerization of styrene containing dispersed organophilic rectorite. The structures and thermal properties of these hybrids have been investigated by X\|ray diffraction (XRD), fourier transform infrared (FT\|IR), positron annihilation spectroscopy (PAS) and thermal gravimetric analysis (TGA) techniques. It was found that exfoliation of rectorite in polystyrene (PS) matrix was achieved. The average free\|volume radius in the PS/clay nanocomposites is generally same as that in PS. Along with increment of rectorite contents, the interface between rectorite and polystyrene matrix increases, and the free\|volume concentration decreases obviously. And the polystyrene nanocomposites have higher thermal decomposition temperature than pure PS.

Adsorption and Insecticidal Activity of Toxin from Bacillus thuringiensis on Rectorite

The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity of the adsorbed toxin was evaluated by determining the lethal concentration to kill 50% of the larvae of Heliothis armigera （LC50）. The adsorption of the toxin on rectorite in sodium carbonate buffer （pH 9） reached equilibrium within 0.5-1.0 h and the adsorption isotherm of the toxin followed the Langmuir equation （R^2 〉 0.99）. In the pH range from 9 to 11 （carbonate buffer）, the adsorbed toxin decreased with increasing pH. The adsorption amounts decreased with increasing rectorite：toxin ratio. The adsorption was not significantly affected by the temperature between 10 and 50 ℃. The X- ray diffraction analysis indicated occurrence of the intercalation of the rectorite by the toxin. The infrared absorption spectrum showed that the binding of the toxin did not alter its structure. The LC50 wlues of the adsorbed toxin were smaller than those of the free toxin. The rectorite protected the toxin from ultraviolet irradiation damage. The desorption of the adsorbed toxin in water ranged from 37.5% to 56.4% and from 27.4% to 41.8% in a carbonate buffer. The desorption percentage also decreased with increasing rectorite：toxin ratio.

Preparation of Granulated Adsorption Material of Water-quenched Slag/rectorite Composite for Removal of Cu(Ⅱ)Ions from Copper Smelter Wastewater

The preparation of granulated adsorption material of water-quenched slag/rectorite composite and the treatment of Cu （ Ⅱ ）-containing copper smelter wastewater with the adsorption material were studied. The experimental results showed that under the conditions with the mass ratio of water-quenched slag to rectorite of 1：1, 10% additive of industrial starch （IS）, and 50% water, and a calcination temperature of 400 ℃, the granulated adsorption material prepared had a density of 1.06 kg/m^3, a porosity of 62.29%, water absorption rate of 58.82%, and compressive strength of 2.22 MPa. The efficiency of wastewater treatment was the best, whereas the rate of spallation loss was low. Under the conditions of natural pH, with the addition of the granulated adsorption material of 0.05 g/mL, a reaction time of 40 minutes, and temperature of 25 ℃, the efficiency of the granulated adsorption material for the removal of Cu （ Ⅱ ） ions from the copper smelter wastewater attained 98.2%, and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard （GB8978-1996）. The reclamation of the used granulated adsorption material was carried out by de-sorption of the Cu （ Ⅱ） ions from the surface with 1 mol/L sodium chloride solution. The de-sorption rate was 96.4%, and the adsorption material can be reused many times to treat copper smelter wastewater.

Preparation of poly(propylene carbonate)/organophilic rectorite nanocomposites via direct melt intercalation

The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC nanocomposites were investigated. The wide-angle X-ray diffraction (WAXD) results show that the galleries distance of OREC is increased after PPC and OREC melt intercalation, which indicates that PPC molecular chain has intercalated into the layers of OREC. The PPC/OREC nanocomposites with lower OREC content show an increase in thermal decomposition temperature compared with pure PPC. The tensile strength and impact strength of PPC/OREC nanocomposites are improved. When the mass fraction of OREC is 4%, the tensile strength and impact strength of the PPC/OREC nanocomposite increase by 22.86% and 48.58% respectively, compared with pure PPC.

ZnO-chitosan/Rectorite Nanocomposite Exhibiting High Photocatalytic Activities under Visible-light Irradiation

Chitosan(CS),hydrated zinc acetate,and rectorite(REC) were used as raw materials to prepare CS-embedded zinc oxide(ZnO) nanoparticle by a chemical precipitation process.Hydrogen-bonded REC-loaded ZnO-CS nanoparticle was to form ZnO-CS/REC nanocomposite photocatalyst,its morphology and structure were analyzed by means of FTIR,XRD,TGA,SEM,and TEM.The effects of the catalyst dosage,methyl orange(MO) initial concentration and solution pH on photocatalytic performance were also discussed.The experimental results show that the ZnO-CS/REC nanocomposite has a particle size of 100 nm with good dispersion and uniformity.Under irradiation of visible light,0.6 g/L photocatalyst was used to degrade MO in solution for 90 min at pH 6,then the MO solution(10 mg/L) was decolored by more than 99%,indicating that the ZnO-CS/REC nanocomposite exhibited highly photocatalytic degradation activity.Therefore,the photodegradation kinetic mechanism of MO in aqueous solution is presumed.

In-situ Synthesis and Catalytic Properties of ZSM-5/Rectorite Composites as Propylene Boosting Additive in Fluid Catalytic Cracking Process

Using rectorite extrudates from calcined rectorite powder as the starting material, a series of ZSM-5/rectorite composites were prepared via the in-situ crystallization method. The physicochemical properties and propylene boosting performance of the resulting samples were characterized by using X-ray diffraction, scan- ning electronic microscopy/energy dispersive spectrometer, N2 adsorption-desorption, and Fourier transformed in/tared spectroscopy of pyndine adsorption, respectively, and assessed by using Daqing atmospheric residue as Iced- stock. The results showed that the ZSM-5/rectorite composites in which the ZSM-5 phase grows inositu as a 2-3 p,m thick layer on rectorite particles have a trimodal microporous-mesoporous-macroporous structure and thus exhibit outstanding propylene boosting performance. Compared with a commercial ZSM-5 incorporated fluid catalytic cracking catalyst, the ZSM-5/rectorite composite incorporated catalyst increased the yield and selectivity of propylene by 2.44% and 5.35%, respectively.

Synthesis and Characterization of Ibuprofen-Rectorite Composites by Solution Intercalation Method

The ibuprofen-rectorite composites were prepared by the solution intercalation method using ibuprofen and rectorite as raw materials, and were characterized by X-ray diffraction （XRD） analysis, Fourier transform infrared analysis and scanning electron microscopy （SEM）. The experimental results show that the ibuprofen is intercalated into the interlayer spaces of rectorite. The values of the （001） peaks of the ibuprofen-rectorite composite are larger than that of Na-rectorite and reach the largest when the reaction time and ibuprofen amount is 2 h and 0.36 g, respectively. The layered structure of Na-rectorite is destroyed to some extent with the intercalation of ibuprofen into the interlayer space in the structure of Na-rectorite. A part of ibuprofen in the ibuprofen Na-rectorite covers on the surface of Na-rectorite besides some ibuprofen enters into the interlayer space.

Synthesis of Cordierite from Rectorite-Talc-Alumina without Additives

Rectorite,Talc and alumina were used to obtain high-quality cordierite with stoichiometric composition (51.3 wt% SiO_2,34.9 wt% Al_2O_3,13.8 wt% Al_2O_3).The water absorption,apparent porosity,bulk density,thermal expansion coefficient,crystalline phases and microstructure were tested by means of X-ray diffractometer(XRD),scanning electronic microscopy(SEM),Archimedes immersion technique,etc.This work systematically studied the synthesizing process of the cordierite.The result shows that the cordierite can be synthesized at a lower temperature and within a wider temperature range by using the rectorite as clay raw materials.

Preparation of Rectorite-TiO_2 and Its Application in the Solar Photocatalytic Degradation of Dye Wastewater

A photocatalyst consisting of TiO2 powder and rectorite was prepared and activated utilizing solar light and used for degradation of simulated dye wastewater （methyl solution）. The effects of roasting temperature, the way of adding rectorite, and the amount of the rectorite on the photocatalytic activity have been investigated. The results indicated that rectorite-TiO2 photocatalyst prepared with the right proportional amount of rectorite and titanium dioxide, could effectively degrade the methyl orange solution in sunlight. After reacting in sunlight for 8 hours, the methyl orange decolorization reached 96%. The photocatalytic activity of rectorite-TiO2 was much better than that of TiO2 in sunlight.

Treatment of Oily Wastewater Using Composite Flocculant of Polysilicate Ferro-Aluminum Sulfate – Rectorite

In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), in order to determine the optimal temperature. The flocculation test was made at 25℃, 45℃ and 65℃, the results indicated that when the temperature was 65℃, the removal efficiency of the oil and COD was the best, which was 87.2% and 92.6% respectively. Then by comparisons among rectorite (REC), PSFA and the composite PSFA-REC at the temperature of 65℃ and the optimal dosage of 11 mg/L, the composite PSFA-REC showed better flocculation performance than flocculant REC and PSFA alone.

Mo supported on natural rectorite catalyst for slurry-phase hydrocracking of vacuum residue:An effect of calcination

In order to develop high-efficiency and low-cost catalyst for the slurry-phase hydrocracking of vacuum residue(VR),the catalyst supported on natural rectorite was prepared,and the effect of calcination modification of rectorite on the catalyst properties and performance was investigated.The support of rectorite and catalyst were characterized by XRD,FTIR,Py-FTIR,H_(2)-TPR and XPS to examine their structures and properties.The comparative reaction results show that VR conversions for the catalysts supported on calcined rectorite were similar with that on raw rectorite,possibly due to the VR cracking reaction controlled by the thermal cracking following free radical mechanism because of few acid sites observed on the catalysts surface.However,the yields of naphtha and middle distillates for the various catalysts were obviously different,and increased following as Rec-Mo(40.4 wt%)

Revealing the atomic mechanism of diamond–iron interfacial reaction

Diamond,with ultrahigh hardness,high wear resistance,high thermal conductivity,and so forth,has attracted worldwide attention.However,researchers found emergent reactions at the interfaces between diamond and ferrous materials,which significantly affects the performance of diamond-based devices.Herein,combing experiments and theoretical calculations,taking diamond–iron(Fe)interface as a prototype,the counter-diffusion mechanism of Fe/carbon atoms has been established.Surprisingly,it is identified that Fe and diamond first form a coherent interface,and then Fe atoms diffuse into diamond and prefer the carbon vacancies sites.Meanwhile,the relaxed carbon atoms diffuse into the Fe lattice,forming Fe_(3)C.Moreover,graphite is observed at the Fe_(3)C surface when Fe_(3)C is over-saturated by carbon atoms.The present findings are expected to offer new insights into the atomic mechanism for diamondferrous material's interfacial reactions,benefiting diamond-based device applications.

Diffusion and reaction mechanism of limestone and quartz in fluxed iron ore pellet roasting process

The increase to the proportion of fluxed pellets in the blast furnace burden is a useful way to reduce the carbon emissions in the ironmaking process.In this study,the interaction between calcium carbonate and iron ore powder and the mineralization mechanism of fluxed iron ore pellet in the roasting process were investigated through diffusion couple experiments.Scanning electron microscopy with energy dispersive spectroscopy was used to study the elements’diffusion and phase transformation during the roasting process.The results indicated that limestone decomposed into calcium oxide,and magnetite was oxidized to hematite at the early stage of preheating.With the increase in roasting temperature,the diffusion rate of Fe and Ca was obviously accelerated,while the diffusion rate of Si was relatively slow.The order of magnitude of interdiffusion coefficient of Fe_(2)O_(3)-CaO diffusion couple was 10^(−10) m^(2)·s^(−1) at a roasting temperature of 1200℃for 9 h.Ca_(2)Fe_(2)O_(5) was the initial product in the Fe_(2)O_(3)-CaO-SiO_(2) diffusion interface,and then Ca_(2)Fe_(2)O_(5) continued to react with Fe_(2)O_(3) to form CaFe_(2)O_(4).With the expansion of the diffusion region,the sillico-ferrite of calcium liquid phase was produced due to the melting of SiO_(2) into CaFe_(2)O_(4),which can strengthen the consolidation of fluxed pellets.Furthermore,andradite would be formed around a small part of quartz particles,which is also conducive to the consolidation of fluxed pellets.In addition,the principle diagram of limestone and quartz diffusion reaction in the process of fluxed pellet roasting was discussed.

Regulatory mechanisms of iron homeostasis in maize mediated by ZmFIT

Regulation of iron homeostasis in maize remains unclear,despite the known roles of FER-Like Fe deficiency-induced transcription factor(FIT)in Arabidopsis and rice.ZmFIT,like At FIT and Os FIT,interacts with iron-related transcription factors 2(ZmIRO2).Here,we investigate the involvement of ZmFIT in iron homeostasis.Mutant ZmFIT lines exhibiting symptoms of Fe deficiency had reduced shoot iron content.Transcriptome analysis revealed downregulation of Fe deficiency-responsive genes in the roots of a Zmfit mutant.ZmFIT facilitates the nuclear translocation of ZmIRO2 to activate transcription of downstream genes under Fe-deficient conditions.Our findings suggest that ZmFIT,by interaction with ZmIRO2,mediates iron homeostasis in maize.Notably,the binding and activation mechanisms of ZmFIT resemble those in Arabidopsis but differ from those in rice,whereas downstream genes regulated by ZmFIT show similarities to rice but differences from Arabidopsis.In brief,ZmFIT,orthgologs of Os FIT and At FIT in rice and maize,respectively,regulates iron uptake and homeostasis in maize,but with variations.