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Chinese Journal of Chemical Engineering 2022年第7期35卷 206-217页

作者： Jing Gao Zhijun Ma Fuli Liu Cunxin Chen School of Mining Liaoning Technical UniversityFuxin 123000China School of Chemical and Environmental Engineering China University of Mining and TechnologyBeijing 100083China

cobalt ferrite has problems such as poor impedance matching and high density,which results in unsatisfactory electromagnetic wave(EMW)absorption *** this study,the CoFe_(2)O_(4)@C core-shell structure composite was synthesized by a two-step hydrothermal method.X-ray diffraction,transmission electron microscopy,Fourier transform infrared spectroscopy,thermogravimetric analysis,and vector network analysis et *** used to test the structure and EMW absorption properties of CoFe_(2)O_(4)@C *** results show that the reflection loss(RL)of the CoFe_(2)O_(4)@C composite reaches the maximum value of25.66 dB at 13.92 GHz,and the effective absorbing band(EAB)is 4.59 GHz(11.20-15.79 GHz)when the carbon mass content is 6.01%.The RL and EAB of CoFe_(2)O_(4)@C composite are increased by 219.55%and 4.59 GHz respectively,and the density is decreased by 20.78%compared with the cobalt *** enhanced EMW absorption properties of CoFe_(2)O_(4)@C composite are attributed to the attenuation caused by the strong natural resonance of the cobalt ferrite,moreover,the carbon coating layer adjusts the impedance matching of the composite,and the introduced dipole polarization and interface polarization can cause multiple Debye relaxation processes.

关键词： cobalt ferrite Core-shell structure composite Electromagnetic wave absorption Impedance matching

Templated synthesis of highly ordered mesoporous cobalt ferrite and its microwave absorption properties

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Chinese Physics B 2014年第8期23卷 147-153页

作者：力国民王连成徐耀 Key Laboratory of Carbon Materials Institute of Coal Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

Based on the nanocasting strategy, highly ordered mesoporous CoFe2O4 is synthesized via the ＇two-solvent＇ im- pregnation method using a mesoporous SBA-15 template. An ordered two-dimensional （P6mm） structure is preserved for the CoFe2O4/SBA-15 composite after the nanocasting. After the SBA-15 template is dissolved by NaOH solution, a mesoporous structure composed of aligned nanoparticles can be obtained, and the P6mm structure of the parent SBA-15 is preserved. With a high specific surface area （above 90 m2/g） and ferromagnetic behavior, the obtained material shows potential in light weight microwave absorption application. The minimum reflection loss （RL） can reach -18 dB at about 16 GHz with a thickness of 2 mm and the corresponding absorption bandwidth is 4.5 GHz.

关键词： two-solvent mesoporous cobalt ferrite microwave absorption

Faujasite zeolite decorated with cobalt ferrite nanoparticles for improving removal and reuse in Pb^2+ions adsorption

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Chinese Journal of Chemical Engineering 2020年第7期28卷 1884-1890页

作者： Elaine C.Paris João O.D.Malafatti Henrique C.Musetti Alexandra Manzoli Alessandra Zenatti Márcia T.Escote Nanotechnology National Laboratory for Agriculture(LNNA) Embrapa InstrumentaçãoXV de Novembro St.145213560-970 São CarlosSPBrazil Department of Chemistry Federal University of São CarlosRod.Washington Luizkm 23513565-905 São CarlosSPBrazil Regional Integrated University of High Uruguay and Missions(URI) Sete de Setembro Ave.162199709-910ErechimRSBrazil Federal University of ABC(UFABC) Avenida dos Estados5001Santo AndréSPBrazil

Water pollution caused by heavy metals ions has been gaining attention in recent years,increasing the interest in the development of methodologies for their efficient removal focusing on the adsorption process for these *** current challenge faced by adsorption processes is the adequate adsorbent immobilization for removal and ***,the present work aimed at producing a faujasite zeolite nanocomposite decorated with cobalt ferrite nanoparticles for Pb^2+ions adsorption in an aqueous medium improving magnetic removal and *** a result,a high surface area(434.4 m^2·g^-1)for the nanocomposite and an 18.93 emu·g^-1 saturation magnetization value were obtained,indicating magnetic removal in a promising material for adsorption *** nanocomposite regeneration capacity evaluated by magnetic recovery after 24 h suspension presented a high Pb^2+ion adsorptive capacity(98.4%)in the first *** 98%of the Pb^2+ions were adsorbed in the second *** this way,the synthesized faujasite:cobalt ferrite nanocomposite reveals itself as a promising alternative in adsorption processes,aiming at a synergic effect of FAU zeolite high adsorptive activity and the cobalt ferrite nanoparticles magnetic activity,allowing for adsorbent recovery from the aqueous medium via magnetic force and successive adsorptive cycles.

关键词： Faujasite zeolite Adsorption cobalt ferrite Nanoparticles Magnetic nanocomposite

Characterization of cobalt ferrite-supported activated carbon for removal of chromium and lead ions from tannery wastewater via adsorption equilibrium

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Water Science and Engineering 2020年第3期13卷 202-213页

作者： Muibat Diekola Yahya Kehinde Shola Obayomi Mohammed Bello Abdulkadir Yahaya Ahmed Iyaka Adeola Grace Olugbenga Department of Chemical Engineering Federal University of TechnologyMinnaP.M.B.65Nigeria Department of Chemical Engineering Landmark UniversityOmu-AranP.M.B.1001Nigeria Department of Chemistry Federal University of TechnologyMinnaP.M.B.65Nigeria

In this experiment,cobalt ferrite-supported activated carbon(CF-AC)was developed and characterized via the wet impregnation method for the removal of Cr and Pb(II)ions from tannery *** adsorption was carried out to evaluate the effect of experimental operating conditions(pH of solution,contact time,adsorbent dose,and temperature),and the removal efficiencies of Cr and Pb(II)ions by the developed adsorbents were calculated and recorded for all experimental *** variables were estimated and reported as removal efficiencies of 98.2%for Cr and 96.4%for Pb(II)ions at the optimal conditions of 5,0.8 g,80 min,and 333 K for pH,adsorbent dose,contact time,and temperature,*** equilibrium for the sorption of Cr and Pb(II)ions was studied using four widely used isotherm models(the Langmuir,Freundlich,Dubinin-Radushkevich,and Temkin isotherm models).It was found that the Freundlich isotherm model fit better with the coefficient of determination(R2)of 0.9484 and a small sum of square error of *** maximum adsorption capacities(Qm)of Pb(II)and Cr adsorbed onto CF-AC were determined to be 6.27 and 23.6 mg/g,*** adsorption process conformed well to pseudo-second order kinetics as revealed by the high R2 values obtained for both *** thermodynamic parameters showed that adsorption of Cr and Pb(II)ions onto CF-AC was spontaneous,feasible,and endothermic under the studied *** mean adsorption energy(E)values revealed that the adsorption mechanism of Cr and Pb(II)by CF-AC is physical in *** results of the study showed that adsorbent developed from CF-AC can be efficiently used as an environmentally friendly alternative adsorbent,for removal of Cr and Pb(II)ions in tannery wastewater.

关键词： Almond husk cobalt ferrite Equilibrium study Heavy metals Adsorption Removal efficiency

Synthesis,structural investigation,dielectric and magnetic properties of Zn^(2+)-doped cobalt ferrite by the sol-gel technique

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Journal of Advanced Dielectrics 2018年第4期8卷 54-59页

作者： Mohammad Sajjad Hossain MdBadiul Alam Mohammad Shahjahan Most.Hosney Ara Begum MdMoazzem Hossain Suravi Islam Nazia Khatun Mukul Hossain Mohammad Saiful Alam Md.Al-Mamun Industrial Physics Division BCSIR Laboratories Dhaka BCSIRDhaka 1205Bangladesh Noakhali Science and Technology University Noakhali 3814 Bangladesh Daffodil International University Dhaka 1205 Bangladesh Atomic Energy Centre Dhaka Dhaka 1000 Bangladesh

Zinc substituted cobalt ferrite nanoparticles with elemental composition Co_(1-x)Zn_(x)Fe_(2)O_(4)(x=0.0,0.2,0.4,0.6)were prepared by the sol-gel auto-combustion technique using Co,Fe,Zn nitrate as a precursor where nitrates to citrate was 1:*** as prepared powder of cobalt zinc ferrite was sintered at 900○C for 3 ***,morphological,dielectric and magnetic properties were studied by x-ray diffractometer(XRD),scanning electron microscope(SEM),high precision impedance analyzer and vibrating sample magnetometer(VSM),*** peaks obtained from the XRD confirmed samples having crystallite(32–36 nm)single phase inverse spinel structure without any traceable *** parameters were calculated from XRD and it increases with Zn *** revealed irregularly shaped grains(-0.5–0.7μm)morphology with heterogeneous *** dielectric constant(ε′)and dielectric loss(tanδ),have been measured as a function of frequency at room *** dependence of ε′ and tan δ with frequency showed the normal dielectric behavior in accordance with the Maxwell-Wagner type of interfacial polarization and electron hopping change between Co^(2+)and Co^(3+)as well as between Fe^(2+)and Fe^(3+)ions at octahedral sites.

关键词： Solgel cobalt ferrite dielectric magnetic properties.

Synthesis and electromagnetic wave absorption properties of Gd-Co ferrite@carbon core-shell structure composites

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Rare Metals 2023年第1期42卷 254-262页

作者： Jing Gao Zhi-Jun Ma Fu-Li Liu Xing-Yuan Weng School of Mining Liaoning Technical UniversityFuxin123000China

Developing high-performance electromagnetic absorbing materials remains a *** this work,Gd-Co ferrite@carbon core-shell structure composites were synthesized by a two-step hydrothermal *** effects of rare earth Gd doping amount on the microstructure and electromagnetic wave absorption properties of cobalt ferrite@carbon composites were mainly *** results show that an appropriate amount of Gd doping can refine the crystal grain size of cobalt ferrite@carbon ***,when the doping amount of Gd exceeds the solid solubility threshold,the secondary phase GdFeO_(3)will be generated and the grain size will *** the doping amount of Gd is x=0.04,the reflection loss(RL) of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites reaches the minimum value of -9.26 dB at the absorption layer thickness of 2.0 mm and a frequency of 13.67 GHz,and the effective absorption band(EAB) is 5.01 GHz(10.95-15.96 GHz).Compared with the CoFe_(2)O_(4)@C composites,the RL of the CoFe_(1.96)Gd_(0.04)O_(4)@C composites is increased by 79.35%,and the EAB is broadened by 3.51%.Gd ions enhance the dielectric loss through the grain size effect,and the increase of magnetocrystalline anisotropy enhances the magnetic *** CoFe_(1.96)Gd_(0.04)O_(4)@C composites have excellent impedance matching,which relies on the strong magnetic loss of ferrite,the interface polarization,and dipole polarization formed by the carbon shell to attenuate electromagnetic waves.

关键词： Rare earth Gd cobalt ferrite Core-shell structure composites Electromagnetic wave absorption

Unraveling the correlation between the remanence ratio and the dipolar field in magnetic nanoparticles by tuning concentration, moment, and anisotropy

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Nano Research 2016年第9期9卷 2772-2781页

作者： Bingqian Geng Zongling Ding Yongqing Ma Anhui Key Laboratory of Information Materials and Devices School of Physics and Materials ScienceAnhui UniversityHefei 230601China

Well-dispersed, uniform cobalt ferrite (CoFe2O4) nanoparticles (NPs) with diameters of 9, 11, 14, and 30 nm were synthesized by thermal decomposition of a metal–organic salt. Multiple variables, including the interparticle distance, moment, and anisotropy, were altered by dilution in a silica matrix and reduction in hydrogen to reveal the intrinsic correlation between the ratio of remanence to saturation magnetization (Mr/Ms) and interparticle dipolar interactions, the strength of which was estimated by the maximum dipolar field Hdip. To date, this correlation has not been systematically investigated experimentally. To prevent the particles from agglomerating, the reduction was performed after dilution. The results revealed that the correlation between Mr/Msand Hdiproughly followed Mr/Ms∝ 1/lgHdipindependent of the size, distance, moment, and anisotropy of the magnetic nanoparticles. In particular, the correlation was closer for the nanoparticle systems that had higher concentrations or moments, that is, stronger dipolar interactions. For the single-phase CoFe2O4nanoparticles, deviation from Mr/Ms∝ 1/lgHdipcan be attributed to the effects of surface spin, and for the slightly reduced nanoparticles, this deviation can be attributed to the pinning effect of CoFe2O4on CoFe2. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： magnetic nanoparticle cobalt ferrite dipolar interaction remanence ratio

Salt-assisted Low Temperature Solid State Synthesis of High Surface Area CoFe_2O_4 Nanoparticles

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Journal of Materials Science & Technology 2009年第1期25卷 69-72页

作者： Runhua Qin Fengsheng Li Wei Jiang Li Liu National Special Superfine Powder Engineering Research Center Nanjing University of Science and Technology Nanjing 210094 China Department of Physics North University of China Taiyuan 030051 China

A novel salt-assisted low temperature solid state method using CoCl2.6H2O, FeCl3.6H2O and NaOH as precursor and using NaCI as a dispersant to synthesize high surface area CoFe2O4 nanoparticles, has been investigated. The effects of the molar ratio of added salt and calcination temperature on the characteristics of the products were investigated by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, vibrating sample magnetometer （VSM） and Brunauer, Emmett and Teller （BET） surface area analysis. Results showed that the introduction of leachable inert inorganic salt as a hard agglomeration inhibitor in the mixture precursor led to the formation of high dispersive CoFe2O4 nanoparticles; and the increase in specific surface area from 28.28 to 73.97 m^2/g, and the saturation magnetization is 84.6 emu/g.

关键词： Low temperature solid state reaction Salt-assisted cobalt ferrite Nanoparticles

Elevated degradation of di-n-butyl phthalate by activating peroxymonosulfate over GO-CoFe_(2)O_(4)composites:Synergistic effects and mechanisms

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Chinese Chemical Letters 2023年第12期34卷 310-317页

作者： Qingliang Liu Hang Qie Zhiqiang Sun Yufei Zhen Liying Wu Ying Zhao Jun Ma State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology.Harbin 150090China

Rational design of heterogeneous catalysts with high activity and stability is crucial in peroxymonosulfate(PMS)-based oxidation treatment of ***,the graphite oxide-cobalt ferrite(GOCoFe_(2)O_(4))composite was constructed,and its morphological,component and structural characteristics were thoroughly examined,***-CoFe_(2)O_(4)obviously boosted PMS catalytic performance on di-n-butyl phthalate removal(DBP,RpBp=90%,Roc=37%),which indicated by the first-order kinetic constant(kpBp=0.060 min^(-1))being roughly 4 times than pure CoFe_(2)O_(4)(kpBp=0.015 min-1).The fabrication of GO-CoFe_(2)O_(4)brought the favorable stability and repeatability up to six ***,the method of batch dosing catalyst was creatively proposed to improve the PMS utilization *** coupling of GO enhanced the dispersion of CoFe_(2)O_(4)particles to obtain sufficient active sites,additionally,the plentiful C=O groups and free-flowing electrons on GO promoted GO-CoFe_(2)O_(4)to coordinate a redox process during PMS *** the aid of theoretical calculations,GO-CoFe_(2)O_(4)was revealed to exhibit a strong affinity toward PMS adsorption,where PMS spontaneously dissociated into sulfate radical(SO_(4)^(·-)),hydroxyl radical(^(·)OH)and singlet oxygen(^(1)O_(2)),acting as the reactive oxygen species(ROSs).Electrons cycling between Co,Fe and O species ensured continuous ROSs generation and excellent catalytic performance.

关键词： Peroxymonosulfate cobalt ferrite Graphene oxide Synergistic effect Di-n-butyl phthalate

CoFe_2O_4/carbon nanotube aerogels as high performance anodes for lithium ion batteries

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Green Energy & Environment 2017年第2期2卷 160-167页

作者： Xin Sun Xiaoyi Zhu Xianfeng Yang Jin Sun Yanzhi Xia Dongjiang Yang School of Environmental Science and Engineering Collaborative Innovation Center for Marine Biomass Fibers Materials and Textiles of Shandong ProvinceCollege of Automation and Electrical Engineering Qingdao University Analytical and Testing Centre South China University of Technology Queensland Micro- and Nanotechnology Centre (QMNC) Griffith University

High-performance lithium ion batteries(LIBs) require electrode material to have an ideal electrode construction which provides fast ion transport, short solid-state ion diffusion, large surface area, and high electric conductivity. Herein, highly porous three-dimensional(3D)aerogels composed of cobalt ferrite(CoFe_2O_4, CFO) nanoparticles(NPs) and carbon nanotubes(CNTs) are prepared using sustainable alginate as the precursor. The key feature of this work is that by using the characteristic egg-box structure of the alginate, metal cations such as Co^(2+)and Fe^(3+) can be easily chelated via an ion-exchange process, thus binary CFO are expected to be prepared. In the hybrid aerogels, CFO NPs interconnected by the CNTs are embedded in carbon aerogel matrix, forming the 3D network which can provide high surface area, buffer the volume expansion and offer efficient ion and electron transport pathways for achieving high performance LIBs. The as-prepared hybrid aerogels with the optimum CNT content(20 wt%) delivers excellent electrochemical properties, i.e., reversible capacity of 1033 mAh g^(-1) at 0.1 A g^(-1) and a high specific capacity of 874 mAh g^(-1) after 160 cycles at 1 A g^(-1). This work provides a facile and low cost route to fabricate high performance anodes for LIBs.

关键词： Alginate Aerogels cobalt ferrite Anode Lithium-ion battery