CoFe2O4纳米阵列催化剂的费托合成性能研究

通过可控的水热生长方法和钴铁碳酸根氢氧根水合物的焙烧在泡沫铁上制备了CoFe₂O₄纳米阵列催化剂。通过粉末X射线衍射,扫描电镜和电感耦合等离子体发射光谱表征了CoFe₂O₄纳米阵列的晶相,结构和组成。制备的催化剂被用于费托合成性能研究。CoFe₂O₄纳米阵列催化剂在5L/（g·h）的空速下具有69%的转化率,并且其性能优于粉体催化剂。     

实验参数对磁性AgI-BiOI/CoFe_2O_4光催化剂湿法脱除Hg~0的影响（英文）

采用水热-共沉淀法制备了一种新型的磁性AgI-BiOI/CoFe_2O_4复合材料光催化剂,考察了荧光灯辐照下光催化剂脱除模拟烟气中单质汞(Hg~0)的性能,研究了实验参数对脱汞性能的影响及反应产物。结果表明,AgI-BiOI/CoFe_2O_4光催化剂的热稳定性较差,当煅烧温度超过400℃时该光催化剂的化学成分会发生变化;随着催化剂用量、反应溶液pH值、反应溶液温度和烟气中O_2浓度的增加,脱汞效率先增加后不变或下降;反应溶液中存在的CO~(2-)_3和SO~(2-)_4对脱汞效率有一定的抑制作用;当通入SO_2时,脱汞效率急剧下降;而NO对脱汞效率的抑制作用相对较小。反应产物分析表明,SO_2、NO和Hg~0的最终氧化产物分别是SO~(2-)_4、NO~(-3)和Hg~(2+)。     

活性炭/CoFe2O4复合物的制备及其对亚甲基蓝的吸附性能

通过低温回流法制备了具有磁分离响应的活性碳(AC)与CoFe₂O₄的复合物AC/CoFe₂O₄（MAC）。采用批式吸附实验法对MAC吸附溶液中偶氮染料亚甲基蓝（MB）的吸附动力学过程及吸附平衡进行了研究,考察了溶液初始pH值对MAC吸附MB的影响。结果表明,MAC吸附MB的过程很快,20 min几乎达到平衡。MAC吸附MB过程可以用准二级动力学方程描述。等温吸附过程服从Langmuir方程,MAC对MB的饱和吸附容量为120.48 mg/g。在较低pH值时,MB吸附量较小。随着pH值的升高,MAC对MB的吸附量增大。     

O2/CO2气氛下O2浓度对燃煤PM2.5形成的影响

采用管式炉和荷电低压撞击器(electrical low pressure-impactor,ELPI)研究了徐州烟煤在O₂/CO₂条件下燃烧后生成的PM_2.5排放特性。结果表明,在O₂/CO₂气氛下,煤粉在不同O₂浓度燃烧所产生的PM_2.5质量浓度均呈双峰分布,峰值分别在0.1和2.0 mm左右;随着氧含量的增加,PM_2.5的质量浓度增加;S、K和Na在亚微米颗粒上明显富集,而Si和Ca未在亚微米颗粒上富集;通过对颗粒物的粒径分布、元素分析和形貌观察,认为亚微米颗粒主要是矿物质蒸发鄄凝结机制形成的,而超微米颗粒主要是煤焦与外部矿物质的破碎以及内在矿物质聚合形成的。     

基于CoFe2O4载氧体的生物质化学链气化热力学分析及实验研究

对基于CoFe₂O₄载氧体的生物质化学链气化反应进行了热力学分析,研究了载氧体添加量、温度及水蒸气含量对气化反应特性的影响。同时应用热重分析仪对CoFe₂O₄和生物质的气化反应特性进行了实验研究,并利用XRD对反应前后载氧体的物相组成进行分析。热力学研究表明,CoFe₂O₄在气化反应中能够提供晶格氧,有效促进生物质气化,提高碳转化率。随着反应温度升高,合成气中H₂和CO的含量增加,CO₂的含量减少。随着水蒸气含量增加,H₂和CO₂含量会增加,CO含量减少。添加水蒸气能够提高合成气中H₂和CO的比值,改善合成气的品质。热重实验及XRD结果表明,钴优先于铁被还原,钴与铁存在协同作用,钴能够促进铁的进一步还原。随着载氧体添加量的增加,载氧体被还原的程度会降低,载氧体与生物质的最佳质量比为0.8。     

磁性Fe3O4/石墨烯Photo-Fenton催化剂的制备及其催化活性

采用共沉淀法制备磁性Fe3O4/GE(石墨烯)催化剂,实现Fe3O4纳米颗粒生长和氧化石墨烯还原同步进行,采用FTIR、XRD、TEM及低温氮吸附-脱附等对Fe3O4/GE纳米催化剂的物相、颗粒粒径及比表面积进行了表征。在H2O2存在条件下,以亚甲基蓝为目标降解物,考察了在模拟太阳光下Fe3O4/GE的催化活性,当氧化石墨烯与Fe3O4的质量比为1∶10时,经过2 h催化反应,在pH=6条件下,对亚甲基蓝的降解率达到98.7%,经过10次循环使用后对染料溶液的降解率仍保持在95.7%以上,明显优于纯的Fe3O4。     

KMnO4溶液改性半焦对烟气中气态Hg0的吸附性能研究

在小型固定床实验台上利用半焦及其KMnO₄溶液改性样品进行气态Hg⁰吸附实验。结果表明,在低温时原料半焦对气态Hg⁰具有良好的吸附性能,升温则使其吸附性能迅速降低;经高锰酸钾溶液浸渍处理后,改性半焦在高温140 ℃时吸附性能明显提高,对浸渍样品在250 ℃进行热处理可使其吸附性能进一步提高。BET结果表明,原料半焦具有较发达的微孔结构,改性处理使微孔比例下降,孔隙结构发达程度降低;XPS测试表明,改性半焦表面的汞主要以氧化态(Hg²⁺)形式存在,高价锰化合物(KMnO₄、K₂MnO₄、MnO₂)是主要的氧化活性物质。     

中空多壳层CoFe2O4的制备及锂离子电池性能研究

以二元金属氧化物CoFe₂O₄为研究对象,通过次序模板法制备了CoFe₂O₄中空多壳层结构(HoMS)材料;对其形貌、结构进行了表征;考察了壳层结构与电化学性能之间的关系.电化学测试结果表明,双壳层-核CoFe₂O₄中空球具有最高的放电比容量(1354.4 mA·h/g)、优异的倍率性能和循环稳定性,其独特的结构优势和最优的空腔体积占有率使其在多次循环过程中能始终保持结构和电化学性质的稳定.     

低阶煤半焦利用热重在O2/CO2、O2/N2和O2/Ar气氛下燃烧特性研究

利用热重研究了两种中国西北典型低阶煤半焦的燃烧特性。探究了不同气氛（O₂/CO₂、O₂/N₂和O₂/Ar）和不同氧气浓度对其燃烧特性的影响。实验结果表明,无论是反应气氛还是氧气浓度都会对低阶煤半焦的燃烧产生影响。相比于N₂和Ar,CO₂明显有利于燃烧反应进行：当反应气氛由O₂/CO₂变为O₂/Ar时,两种不同低阶煤半焦的燃尽温度分别升高了63.7和68.8℃;而当反应气氛由O₂/CO₂变为O₂/N₂时,两种不同低阶煤半焦的燃尽温度分别升高了135.9和129.6℃。在研究范围内,氧气浓度的提高也能明显提高半焦的燃烧性能。与此同时,半焦燃烧特性的动力学分析表明,随着氧气浓度提高,两种半焦燃烧反应的表观活化能E和指前因子A均呈增大趋势。通过对E和A两者关系的分析结果表明,半焦富氧燃烧的活化能和指前因子存在动力学补偿效应。     

复杂烟气条件下太西活性焦脱除Hg0的实验研究

为了解复杂烟气条件下活性焦吸附剂的脱汞特性,利用汞渗透管和主要气体成分模拟复杂烟气,在实验室规模的固态吸附剂汞吸附效能测定系统上,进行了太西活性焦吸附单质汞的实验研究,并采用FT-IR对活性焦表面进行了光谱表征。结果表明,在活性焦表面存在各种含氧官能团;在CO₂/N₂/O₂/SO₂/Hg⁰烟气体系中,当SO₂加入量为400、855、1 520 mL/m³时,出口汞浓度分别为36、43、48 μg/m³,SO₂对系统吸附Hg⁰的能力有抑制作用;在CO₂/N₂/O₂/NO/Hg⁰烟气体系中,较低浓度的NO对Hg⁰脱除有抑制作用,而高浓度值的NO抑制作用减弱;在CO₂/N₂/O₂/NO/SO₂/Hg⁰烟气体系下,提高NO浓度对Hg⁰脱除有一定的促进作用,而提高SO₂浓度初期促进汞的脱除,后期则表现为抑制作用。     

Hydrothermal synthesis of magnetic CoFe2O4 nanoparticles and CoFe2O4/MWCNTs nanocomposites for U and Pb removal from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - Magnetite CoFe2O4 nanoparticle and CoFe2O4/MWCNT nanocomposite adsorbents with high specific surface area, high adsorption capacity, and easily...     

Efficient removal of organic pollutant by activation of persulfate with magnetic Co3O4/CoFe2O4 composite

In this study, magnetic spinel Co₃O₄/CoFe₂O₄ composite were synthesized by the mechanical mixing of both powdered pristine samples. Then the catalyst was characterized by TEM, SEM, XRD, BET, XPS and VSM measurement. Next, Co₃O₄/CoFe₂O₄ composite was applied to degrade rhodamine B (RhB) in water by activating persulfate. Results showed that Co₃O₄/CoFe₂O₄ composite exhibited high efficiency for removal of RhB, and 95.59% of it could be degraded in 45 min. Besides, the effects of parameters, such as initial pH, PS dosage, Co₃O₄/CoFe₂O₄ composite dosage, initial concentration of RhB and temperture were studied. Also, the effects of coexisting anions on RhB degradation were observed and explained. Furthermore, we conducted the quenching experiment and found that sulfate radical and hydroxyl radicals were the main active radicals in the degradation process. Finally, recycle experiments proved that Co₃O₄/CoFe₂O₄ had a good stability for RhB degradation. In short, Co₃O₄/CoFe₂O₄ composite is a promising catalyst for wastewater treatment.     

Preparation of CoFe2O4/sawdust and NiFe2O4/sawdust magnetic nanocomposites for removal of oil from the water surface

In this study, CoFe₂O₄/Sawdust and NiFe₂O₄/Sawdust magnetic nanocomposites were synthesized using a hydrothermal method, and then characterized using X-ray powder diffraction, Infrared, scanning electron microscopy, Brunauer–Emmett–Teller/Barrett–Joyner–Halenda, and vibrating-sample magnetometer techniques. In this study, unmodified sawdust (US), modified sawdust (MS), unmodified CoFe₂O₄/sawdust (UCS), modified CoFe₂O₄/sawdust (MCS), unmodified NiFe₂O₄/sawdust (UNS), and modified NiFe₂O₄/Sawdust (MNS) magnetic nanocomposites, which are inexpensive, economical, environmentally friendly absorbents, and have a high selective hydrophobic, were used for the removal of oil from the water surface. The results show that the UCS, MCS, UNS, and MNS magnetic nanocomposites can selectively absorb the oil spreading on the water surface, due to its superhydrophobicity and superoleophilicity, and can be easily collected from water under the influence of a magnetic field. In addition, the results showed that the absorbents reach their equilibrium at the 30-min mark. Among all the absorbents, the MNS magnetic nanocomposite showed the maximum absorption capacity (18.172 g/g) at the 40-min mark. The results of the kinetic studies showed that the second-order kinetic equation with the highest correlation coefficient had the best fit with the experimental results.     

Magnetically separable ZnO/ZnFe2O4 and ZnO/CoFe2O4 photocatalysts supported onto nitrogen doped graphene for photocatalytic degradation of toxic dyes

Advanced oxidation processes (AOPs) counting heterogeneous photocatalysis has confirmed as one of the preeminent method for waste water remediation. In the present work, we have successfully fabricated novel visible-light-driven nitrogen-doped graphene (NG) supported magnetic ZnO/ZnFe₂O₄ (ZnO/ZF/NG) and ZnO/CoFe₂O₄ (ZnO/CF/NG) nanocomposites. ZnO synthesized via direct precipitation method. Hydrothermal method was used for the preparation of nitrogen-doped graphene supported magnetic ZnO/ZF (ZnO/ZnFe₂O₄) and ZnO/CF (ZnO/CoFe₂O₄) nanocomposites. The procured materials were scrutinized by assorted characterizations to acquire information on their chemical composition, crystalline structure and photosensitive properties. The absorption and photocatalytic performance of photocatalysts were studied via UV–Visible spectra. Photodegradation performance of the synthesized nanocomposites was estimated toward mineralization of methyl orange (MO) and malachite green (MG) dyes in aqueous solution. The high surface area of ZnO/ZF/NG and ZnO/CF/NG was suitable for adsorptive removal of MO and MG dyes. The photodegradation performance of heterojunction photocatalysts was superior to bare photocatalyst in 140 min under visible-light irradiation. Spectrophotometer, GC–MS (Gas chromatography–mass spectrometry) elucidation was carried out to expose the possible intermediates formed. Both ZnO/ZF/NG and ZnO/CF/NG were rapidly isolated from the aqueous phase by applying an external magnetic field in 20 sec and 2 min, respectively. The photocatalytic performance and stability of ZnO/ZF/NG and ZnO/CF/NG nanocomposites were confirmed by conducting 10 consecutive regeneration cycles. Owing to recyclability of ZnO/ZF/NG and ZnO/CF/NG, these heterogeneous nanocomposites might be used as cost-effective for treatment of discarded water. The observations endorse that the synthesized ternary heterogeneous nanocomposites facilitates wastewater decontamination using photocatalytic technology.     

Synthesis of 2,4,5‐trisubstituted imidazoles over reusable CoFe2O4 nanoparticles: an efficient and green sonochemical process

Numerous reports of the synthesis of 2,4,5‐trisubstituted imidazoles demonstrate their significance as biologically important molecules. Here we carried out their fast and efficient one‐step green sonochemical synthesis through condensation of aldehyde, diketone and ammonium acetate, over reusable superparamagnetic CoFe₂O₄ nanoparticles. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation of magnetic separable CoFe2O4/PAC composite and the adsorption of bisphenol A from aqueous solution

CoFe₂O₄/PAC composite adsorbent has been prepared via an immersing-calcination process, using ethylene diamine tetraacetic acid (EDTA) and citric acid (CIT) ligands containing sol as the CoFe₂O₄ precursor. The microstructure characterization and magnetic property of as-prepared sample were performed by means of XRD and VSM measurements. The adsorption kinetics, isotherms and thermodynamic process toward Bisphenol A molecules (BPA, which is considered as one of the typical endocrine disrupting chemicals) occurred on as-prepared magnetic adsorbent which were investigated by the pseudo-second order kinetic/intraparticle models, the Langmuir/Freundlich adsorption isothermal models and basic chemical thermodynamics principles, respectively.     

Synthesis and characterization of CoFe2O4@SiO2-polyethyleneimine magnetic nanoparticle and its application for ultrasonic-assisted removal of disulfine blue dye from aqueous solution

In the present work, a simple synthesis approach was applied for the fabrication of CoFe₂O₄@SiO₂-polyethyleneimine magnetic nanoparticles as an effective sorbent for ultrasonic-assisted removal of disulfine blue dye from an aqueous solution. For identification and characterization of prepared sorbent, different analysis including Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), Energy dispersive X-ray analysis (EDX) and Transmission electron microscopy (TEM) were applied. The effect of effective parameters on the removal of disulfine blue such as pH, sorbent mass, ultrasonic time and disulfine blue concentration were also assessed. The optimum values for investigated parameters were achieved to be as follows: pH of 5.0, sorbent mass of 0.015 g, ultrasonic time of 5.0 min and disulfine blue concentration of 10.0 mg L⁻¹. Different isotherm and kinetic models were used for the evaluation of isotherm and kinetic of adsorption. Results showed that the Langmuir isotherm model was better than other isotherm models as well as the second-order equation model was selected as a kinetic model. The maximum adsorption capacity of the proposed magnetic sorbent was achieved to be 110.0 mg g⁻¹ which shows the applicability of proposed sorbent for removal of disulfine blue dye from aqueous solution.     

Novel CuFe2O4@SiO2‐OP2O5H magnetic nanoparticles: Preparation,characterization and first catalytic application to the synthesis of 1,8‐dioxo‐octahydroxanthenes

New functionalized magnetic core–shell nanoparticles, CuFe₂O₄@SiO₂‐OP₂O₅H, were prepared by grafting of phosphorus pentoxide on CuFe₂O₄@SiO₂ nanoparticles and characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, inductively coupled plasma optical emission spectrometry and vibrating sample magnetometry. The catalytic activity of CuFe₂O₄@SiO₂‐OP₂O₅H as a novel catalyst was evaluated in the synthesis of 1,8‐dioxo‐octahydroxanthenes under solvent‐free conditions. The results showed that the catalyst has high activity and the desired products are obtained in high yields within short reaction times. The catalyst is readily recovered using magnetic decantation and can be used at least four times without noticeable deterioration in catalytic activity.     

Study on the effect of process parameters on CO2/CH4 binary gas separation performance over NH2-MIL-53(Al)/cellulose acetate hollow fiber mixed matrix membrane

The aim of current work is to study the interaction of process parameters including, temperature, CO₂ feed composition and feed pressure were towards CO₂ separation from CO₂/CH₄ binary gas mixture over hollow fiber mixed matrix membrane using design of experiment (DoE) approach. The hollow fiber mixed matrix membrane (HFMMM) containing NH₂-MIL-53(Al) filler and cellulose acetate polymer was successfully spun and fibers with outer diameter of approximately 250–290 nm were obtained. The separation results revealed that the increment of temperature from 30 °C to 50 °C reduced the CO₂/CH₄ separation factor while, increasing feed pressure from 3 bar to 15 and increment of CO₂ feed composition from 15 to 42.5 vol% increased the separation factor of HFMMM. The DoE results showed that the feed pressure was the most significant process parameter that intensely affected the CH₄ permeance, CO₂ permeance and CO₂/CH₄ separation factor. Based on the experimental results obtained, maximum CO₂ permeance of 3.82 GPU was achieved at feed pressure of 3 bar, temperature of 50 °C and CO₂ feed composition of 70 vol%. Meanwhile, minimum CH₄ permeance of 0.01 GPU was obtained at feed pressure of 15 bar and temperature of 30 °C and CO₂ feed composition of 70 vol%. Besides, maximum CO₂/CH₄ separation factor of 14.4 was achieved at feed pressure of 15 bar and temperature of 30 °C and CO₂ feed composition of 15 vol%. Overall, the study on the interaction between separation processes parameters using central composite design (CCD) coupled with response surface methodology (RSM) possesses significant importance prior to the application of NH₂-MIL-53(Al)/Cellulose Acetate HFMMM at industrial scale of natural gas purification.     

Effects of operating parameters on oxidative coupling of methane over Na-W-Mn/SiO2 catalyst at elevated pressures

The effects of operating parameters on oxidative coupling of methane (OCM) over Na-W-Mn/SiO2 catalyst have been studied at elevated pressures of 0.2, 0.3 and 0.4 MPa under low gaseous hourly space velocity (GHSV) and low temperature conditions. Experimental results show that when the operating pressure is increased, C2+ yield slightly decreases, while the maximum ratio of ethylene to ethane remains unchanged. Moreover, it has been found empirically that increase of pressure does not affect the catalyst behavior permanently, the catalyst recovers its original low pressure performance without hysteresis behavior by reducing the pressure. Under the investigated conditions, when oxygen is completely consumed, the increase of GHSV leads to improvement in C2 selectivity, while C3+ and COx selectivities decrease slightly. The C2+ selectivity increases by increase of nitrogen diluent in the feed, but the C3+ hydrocarbons selectivities decrease with increase of nitrogen since it is possible that further dilution at high pressure may reduce the probability of collision between CH3 and C2+ hydrocarbons. During the stability test at high pressure, the catalyst performance remains unchanged throughout the 20 h running. The fresh and used catalysts were characterized using XRD, SEM and N2 adsorption-desorption methods. It was found that the phase transformation of the support from α-cristobalite to tridymite and quartz does not have obvious effect on catalyst performance at high pressure.