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Determination of impurity elements in MnZn ferrites by inductively coupled plasma mass spectrometry

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Journal of Central South University 2015年第1期22卷 37-42页

作者：张萍符靓马俊才唐有根 college of Materials and chemical Engineering Hunan Institute of Technology School of Chemistry and chemical Engineering Central South University college of Chemistry and chemical Engineering Yangtze Normal University Chongqing Shangjia Electronics Co. Ltd.

An inductively coupled plasma mass spectrometry(ICP-MS) method was developed for the determination of Na, Mg, Al,K, Ca, Ti, Cr, Co, Ni, Cu, Ga, As, Mo, Ag, Cd and Pb in MnZn ferrites. The sample was digested by HNO3+HCl with microwave digestion followed by dilution with ultrapure water, then the above 16 impurity elements in the solution were analyzed directly by ICP-MS. The impurity elements were introduced by the helium gas or hydrogen gas into the octopole reaction system(ORS) to eliminate the polyatomic interferences caused by the high salty matrixes. The matrix effect was minimized through matrix matching,and Be, Y and Rh were used as internal standard elements. The working parameters of the instrument were optimized. The results show that the method has good precision and high accuracy. The detection limits for the investigated elements are in the range of0.9-37.5 ng/L, the relative standard deviation of each element is within 1.1%-4.8%, and the recovery of each element is 90%-108%.

关键词： inductively coupled plasma mass spectrometry(ICP-MS) MnZn ferrites octopole reaction system(ORS) impurity elements

Rational design of practical layered transition metal oxide cathode materials for sodium-ion batteries

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Frontiers of chemical Science and Engineering 2024年第7期18卷 121-140页

作者： Yan Wang Ning Ding Rui Zhang Guanhua Jin Dan Sun Yougen Tang Haiyan Wang hunan Provincial Key Laboratory of chemical Power Sources College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China college of Energy and chemical Engineering Xinjiang Institute of TechnologyAksu Prefecture 843100China

Sodium-ion batteries (SIBs), which serve as alternatives or supplements to lithium-ion batteries, have been developed rapidly in recent years. Designing advanced high-performance layered NaxTMO_(2) cathode materials is beneficial for accelerating the commercialization of SIBs. Herein, the recent research progress on scalable synthesis methods, challenges on the path to commercialization and practical material design strategies for layered NaxTMO_(2) cathode materials is summarized. Co-precipitation method and solid-phase method are commonly used to synthesize NaxTMO_(2) on mass production and show their own advantages and disadvantages in terms of manufacturing cost, operative difficulty, sample quality and so on. To overcome drawbacks of layered NaxTMO_(2) cathode materials and meet the requirements for practical application, a detailed and deep understanding of development trends of layered NaxTMO_(2) cathode materials is also provided, including high specific energy materials, high-entropy oxides, single crystal materials, wide operation temperature materials and high air stability materials. This work can provide useful guidance in developing practical layered NaxTMO_(2) cathode materials for commercial SIBs.

关键词： sodium-ion batteries layered oxide industrialization development prospect

A rapid method for determination of acid value in transformer oil by PPy modified electrode

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Journal of Central South University 2014年第6期21卷 2202-2207页

作者：熊英何德良冯勇周舟常新园刘芙蓉 college of Chemistry and chemical Engineering Hunan University hunan Electric Power Corporation Research Institute

A polypyrrole-modified glassy carbon electrode （PPy/GC electrode） was prepared and its electrocatalytic behavior towards naphthoquinone in the presence of acid was characterized by linear sweep voltammetry （LSV）. A well-defined new reduction peak appeared at a more positive potential than the original reduction peak. The new reduction peak current was linearly related to the acid value （AV） of oil. Based on it, a rapid electrochemical method for determining AV of transformer oil was developed using PPy/GC electrode. A working curve was obtained in the AV range of 0.01 to 0.40 mg（KOH）.g^-1, with a sensitivity of 39.42 μA0.5/（mg（KOH）.g-l） and the detection limit of 0.0014 mg（KOH）.g^-1 （signal-to-noise ratio is 3, standard deviation is 2.247%）. Moreover, the proposed method has been successfully applied to AV determination of several transformer oil samples with advantages of rapidness, high sensitivity and accuracy compared to the conventional method.

关键词： acid value voltammetry polypyrrole-modified electrode transformer oil

Fabrication of GO/magnetic graphitic nanocapsule/TiO_2 assemblies as efficient and recyclable photocatalysts

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Science China Chemistry 2015年第7期58卷 1131-1136页

作者： Zhenqian Cheng Ding Ding Xiangkun Nie Yiting Xu Zhiling Song Ting Fu Zhuo Chen Weihong Tan Molecular Science and Biomedicine Laboratory State Key Laboratory of Chemo/Bio-Sensing and Chemometrics Hunan University college of Biology Hunan University college of Chemistry and chemical Engineering Hunan University

In this work, we fabricate an efficient and stable photocatalyst system which has superior recyclability even under concentrated acidic conditions. The photocatalyst is prepared by assembling magnetic graphitic nanocapsules, titania(Ti O2) and graphene oxide(GO) into a complex system through π-π stacking and electrostatic interactions. Such catalytic complex demonstrates very high stability. Even after dispersal into a concentrated acidic solution for one month, this photocatalyst could still be recycled and maintain its catalytic activity. With methyl orange as the model molecule, the photocatalyst is demonstrated to rapidly decompose the molecules with very high photocatalytic activity under both concentrated acidic and neutral condition. Moreover, this photocatalyst retains approximately 100 wt% of its original photocatalytic activity even after multiple experimental runs, of magnetic recycling. Finally, using different samples from natural water sources and different dyes, this GO/ magnetic graphitic nanocapsule/Ti O2 system also demonstrates its high efficiency and recyclability for practical application.

关键词： magnetic graphitic nanocapsule graphene oxide TiO2 photocatalyst recyclability

A Homotopy Alternating Direction Method of Multipliers for Linearly Constrained Separable Convex Optimization

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Journal of the Operations Research Society of China 2017年第2期5卷 271-290页

作者： Jiao Yang Yi-Qing Dai Zheng Peng Jie-Peng Zhuang Wen-Xing Zhu hunan vocational Institute of Safety technology Changsha 410018China college of Mathematics and Computer Science Fuzhou UniversityFuzhou 350108China

Linearly constrained separable convex minimization problems have been raised widely in many real-world *** this paper,we propose a homotopy-based alternating direction method of multipliers for solving this kind of *** proposed method owns some advantages of the classical proximal alternating direction method of multipliers and homotopy *** some suitable condi-tions,we prove global convergence and the worst-case O(k/1)convergence rate in a nonergodic *** numerical results indicate effectiveness and efficiency of the proposed method compared with some state-of-the-art methods.

关键词： Separable convex optimization Alternating direction method of multipliers Proximal point algorithm Homotopy method

Effect of iron ion configurations on Ni^(2+) removal in electrocoagulation

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Journal of Environmental Sciences 2023年第2期124卷 823-834页

作者： Xiaoliu Lü Tao Xu Yihui Zhou Qingjuan Peng Jinhua Ou Bonian Hu Zhihui Xie Xiping Lei Gang Yu college of Chemistry and chemical Engineering Hunan UniversityChangsha 410082China Research Institute of New Building Materials Hunan Institute of TechnologyHengyang 421008China chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province College of Chemistry and Chemical EngineeringChina West Normal UniversityNanchong 637002China hunan Zihong Ecology technology Co. Ltd.Changsha 410000China

Electrocoagulation(EC)has been widely used to treat the heavymetal wastewater in industry.A novel process of sinusoidal alternating current electrocoagulation(SACC)is adopted to remove Ni2+in wastewater in this *** morphology of precipitates and the distribution of the main functional iron configurations were *** timed complex spectroscopy can identify the monomeric iron configurations[Fe(a)],oligomeric iron configurations[Fe(b)]and polymeric iron configurations[Fe(c)].The optimal operating conditions of SACC process were determined through single-factor *** maximum Ni2+removal efficiency[Re(Ni^(2+))]was achieved under the conditions of pH0=7,current density(j)=7 A/m^(2),electrolysis time(t)=25 min,c0(Ni^(2+))=100 mg/*** pH=7,the proportion of Fe(b)and Fe(c)in the system was 50.4 at.% and 23.1 at.%,*** the SACC process,Fe(b)and Fe(c)are themain iron configurations in solution,while Fe(c)are the vastmajority of the iron configurations in the direct current electrocoagulation(DCC)***(Ni2+)is 99.56% for SACC and 98.75% for DCC under the same optimum conditions,*** precipitates produced by SACC have a high proportion of Fe(b)configurations with sphericalα-FeOOH andγ-FeOOH structures which contain abundant hydroxyl ***,it is demonstrated that Fe(b)has better adsorption capacity than Fe(c)through adsorption experiments of methyl orange(MO)***(a)configurations in the homogeneous solution had no effect on the removal of nickel.

关键词： Electrocoagulation Nickel wastewater Iron configurations Alternating current Polynuclear iron-hydroxyl complex

Unveiling localized electronic properties of ReS2 thin layers at nanoscale using Kelvin force probe microscopy combined with tip-enhanced Raman spectroscopy

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Chinese Physics B 2023年第11期32卷 598-603页

作者：罗宇苏伟涛张娟娟陈飞武可曾宜杰卢红伟 School of Sciences Hangzhou Dianzi UniversityHangzhou 310018China hunan Petrochemical vocational technology college Yueyang 414011China college of Materials and Environmental Engineering Hangzhou Dianzi UniversityHangzhou 310018China

Electronic properties of two-dimensional(2D) materials can be strongly modulated by localized strain. The typical spatial resolution of conventional Kelvin probe force microscopy(KPFM) is usually limited in a few hundreds of nanometers, and it is difficult to characterize localized electronic properties of 2D materials at nanoscales. Herein, tip-enhanced Raman spectroscopy(TERS) is proposed to combine with KPFM to break this restriction. TERS scan is conducted on ReS2bubbles deposited on a rough Au thin film to obtain strain distribution by using the Raman peak shift. The localized contact potential difference(CPD) is inversely calculated with a higher spatial resolution by using strain measured by TERS and CPD-strain working curve obtained using conventional KPFM and atomic force microscopy. This method enhances the spatial resolution of CPD measurements and can be potentially used to characterize localized electronic properties of 2D materials.

关键词： few layer ReS2 tip enhanced Raman spectroscopy local strain Kelvin probe force microscopy

Trace amounts of impurities in electrolytic manganese metal by sector field inductively coupled plasma mass spectrometry

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Journal of Central South University 2013年第12期20卷 3385-3390页

作者：聂西度梁逸曾唐有根谢华林 School of Chemistry and chemical Engineering Central South University Department of Material and chemical Engineering Hunan Institute of Technology college of Chemistry and chemical Engineering Yangtze Normal University

An analytical method, using sector field inductively coupled plasma mass spectrometry （SF-ICP-MS） for rapid simultaneous determination of Be, Na, Mg, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, As, Sn, Sb, Pb and Bi in electrolytic manganese metal, was described. At the beginning, the samples were decomposed by HNO3 and H2504, and then analyzed by SF-ICP-MS. Most of the spectral interferences could be avoided by measuring in different mass resolution modes. The matrix effects due to the excess of sulfuric acid and Mn were evaluated. Correction of matrix effects was conducted by using the internal standard elements. The optimum condition for the determination was investigated and discussed. The detection limit is in the range of 0.001-0.169 gg/L. The current method is applied to the determination of trace impurities in electrolytic manganese metal. And experiments show that good results can be obtained much faster, more accurately and conveniently by current method.

关键词： sector field inductively coupled plasma mass spectrometry electrolytic manganese impurities spectral interferences matrix effects

Liquid-liquid two-phase flow in a wire-embedded concentric microchannel: Flow pattern and mass transfer performance

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Chinese Journal of chemical Engineering 2023年第4期56卷 281-289页

作者： Ming Chen Huiyan Jiao Jun Li Zhibin Wang Feng He Yang Jin Engineering Research Center of Comprehensive Utilization and Clean Processing of Phosphorus Resources School of Chemical EngineeringSichuan UniversityChengdu 610065China The Key Laboratory of Fine chemical Application technology of Luzhou Sichuan Vocational College of Chemical TechnologyLuzhou 646300China

In this work, flow pattern and mass transfer of liquid-liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene-water system. Droplet flow, slug flow, oval flow and annular flow are observed in the wire-embedded concentric microchannel. The effects of embedded wires and physical properties on flow patterns are investigated. The embedded wire insert is conducive to the formation of annular flow. The flow pattern distribution regions are distinguished by the Caaq(capillary number)±We_(org)(Weber number) flow pattern map. When Weorg0.1, annular flow is the main flow pattern. Oval flow and droplet flow are between We_(org)= 0.001-0.1, and oval flow is transformed into droplet flow with the increase of Caaq. The effect of flow rate, phase ratio, initial acetic acid concentration, insert shape and flow patterns on mass transfers are studied. Mass transfer process is enhanced under annular flow conditions, the volumetric mass transfer coefficient is up to 0.36 s^(-1) because of the high interfacial area and interface renewal rate of annular flow.

关键词： Flow pattern Mass transfer Microchannels Two-phase flow