LiNiPO4前驱体固相反应合成动力学及电容性能

以氢氧化锂、磷酸二氢铵和醋酸镍为原料,以聚乙二醇PEG-400为表面活性剂,采用前驱体固相活化法制备LiNiPO4纳米晶材料.固相制备过程的活化能E=81.08 kJ·mol-1,过程动力学为二维相界面扩散反应机理.前驱体生成LiNiPO4的反应符合界面反应指数成核机理,活化能E1=11.82 kJ·mol-1,指前因子lnA=13.82;LiNiPO4晶体生长过程具有较小的活化能E2=17.73 kJ·mol-1;Li3PO4转化反应和反应体系物系晶化过程符合二维相界面扩散反应机理,其是制备过程可控制的重要步骤.材料复合电极LiNiPO4+Nafion/C在0.5 mol·L-1H2SO4中具有典型的电容性能,电极比电容为214 F·g-1,经1 000次循环,电极电容量不但没有衰减反而略有增加,是潜在的电容器材料.     

Isothermal reduction kinetics of Panzhihua ilmenite concentrate under 30vol% CO-70vol% N2 atmosphere

The reduction of ilmenite concentrate in 30vol% CO-70vol% N₂ atmosphere was characterized by thermogravimetric and differential thermogravimetric (TG-DTG) analysis methods at temperatures from 1073 to 1223 K. The isothermal reduction results show that the reduction process comprised two stages; the corresponding apparent activation energy was obtained by the iso-conversional and model-fitting methods. For the first stage, the effect of temperature on the conversion degree was not obvious, the phase boundary chemical reaction was the controlling step, with an apparent activation energy of 15.55-40.71 kJ·mol-1. For the second stage, when the temperatures was greater than 1123 K, the reaction rate and the conversion degree increased sharply with increasing temperature, and random nucleation and subsequent growth were the controlling steps, with an apparent activation energy ranging from 182.33 to 195.95 kJ·mol-1. For the whole reduction process, the average activation energy and pre-exponential factor were 98.94-118.33 kJ·mol-1 and 1.820-1.816 min-1, respectively.     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

Synthesis of glass ceramics from kaolin and dolomite mixture

Cordierite-and anorthite-based binary glass ceramics of the CaO-MgO-Al₂O₃-SiO₂ (CMAS) system were synthesized by mixing local and abundant raw minerals (kaolin and doloma by mass ratio of 82/18). A kinetics study reveals that the activation energy of crystallization (Ea) calculated by the methods of Kissinger and Marotta are 438 kJ·mol-1 and 459 kJ·mol-1, respectively. The Avrami parameter (n) is estimated to be approximately equal to 1, corresponding to the surface crystallization mechanism. X-ray diffraction (XRD) analysis shows that the anorthite and cordierite crystals are precipitated from the parent glass as major phases. Anorthite crystals first form at 850℃, whereas the μ-cordierite phase appears after heat treatment at 950℃. Thereafter, the cordierite allotropically transforms to α-cordierite at 1000℃. Complete densification is achieved at 950℃; however, the density slightly decreases at higher temperatures, reaching a stable value of 2.63 kg·m-3 between 1000℃ and 1100℃. The highest Vickers hardness of 6 GPa is also obtained at 950℃. However, a substantial decrease in hardness is recorded at 1000℃; at higher sintering temperatures, it slightly increases with increasing temperature as the α-cordierite crystallizes.     

Study on the reaction of carbon disulfide with hydroxyl radical in aqueous solution

Carbon disulfide is an important sulfur-containing compound in the environment, and its oxidation produces about 30% of the atmospheric COS[1]. In situ measure- ments show that CS2 is widespread in the sea surface wa- ters[2―4], and more recently, the continental water seems to be especially rich sources of CS2 due to industrial waste- water effluents. It is generally accepted that the ocean is an important source for atm. CS2, and Xie et al.[5] found that marine photochemical reaction of…     

计时电量法测定4,5-二氮芴-9-酮的扩散系数和反应速率常数

运用循环伏安法测定4,5-二氮芴-9-酮（DAFO）在DMF溶液中不同扫描速率时的循环伏安图,出现2对峰形良好的氧化还原峰;采用计时电量法通过控制阶跃电位,测得不同温度下DAFO在DMF溶液中的扩散系数和反应速率常数,293K时扩散系数为5.39×10-6cm2·s-1;当选择阶跃电位使电极过程处于扩散和电化学混合控制时,测得不同电位的反应速率常数k_f. 根据不同温度下的标准速率常数k₀,得到表观活化能E_a为10.5kJ·mol-1.      

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl<Subscript>3</Subscript> and HCl/H<Subscript>2</Subscript>O<Subscript>2</Subscript>

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl₃/HCl and H₂O₂/HCl has been undertaken. The dissolution kinetics of the galena was found to depend on leachant concentration, reaction temperature, stirring speed, solid-to-liquid ratio, and particle diameter. The dissolution rate of galena ore increases with the increase of leachant concentration, reaction temperature, and stirring speed, while it decreases with the increase of solid-to-liquid ratio and particle diameter. The activation energy (E _a) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl₃/8.06 M HCl, and it suggests the surface diffusion model for the leaching reaction, while the E _a value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H₂O₂/8.06 M HCl, which suggests the surface chemical reaction model for the leaching reaction. Furthermore, the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases. Finally, the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model. The Arrhenius and reaction constants of 11.023 s⁻¹, 1.25×10⁴ and 3.65×10² s⁻¹, 8.02×10⁶ were calculated for the 0.3 M FeCl₃/8.06 M HCl and 8.06 M H₂O₂/8.06 M HCl binary solutions, respectively.     

超声波下酸化碘酸钾和亚硫酸钠反应的反应速率研究

分别测定在有超声波作用和在无超声波作用条件下 ,酸化碘酸钾 (KIO3 )和亚硫酸钠 (Na2 SO3 )反应的反应速率方程式及活化能 ,从而研究该反应的机理以及超声波在该反应中的作用 ,并确定反应的最佳条件。实验得出 ,超声波对该反应有一定的促进作用 ,但是这种促进作用只提高反应的速率常数和降低反应的活化能 ,并没有改变反应机理。在超声波功率为 30 0W时 ,反应的速率方程表示式为 :v =k·c1 0 9(KIO3 ) ·c1 0 0 (Na2 SO3 )·c1 0 8(H+ ) ,其中 :k =95 0 (mol-1·L) 2 ·s-1,活化能为 17 35kJ·mol-1。实验还得出 ,在温度为2 98K时 ,当KIO3 与Na2 SO3 的初始浓度比为 2∶5 ,H+ 的初始浓度为 0 0 4 2 8mol·L-1,超声功率为 30 0W时 ,反应速率为最快 ,即v =4 31× 10 -4mol·L-1·s-1)。     

Isothermal reduction of titanomagnetite concentrates containing coal

The isothermal reduction of the Panzhihua titanomagnetite concentrates (PTC) briquette containing coal under argon atmosphere was investigated by thermogravimetry in an electric resistance furnace within the temperature range of 1250–1350℃. The samples reduced in argon at 1350℃ for different time were examined by X-ray diffraction (XRD) analysis. Model-fitting and model-free methods were used to evaluate the apparent activation energy of the reduction reaction. It is found that the reduction rate is very fast at the early stage, and then, at a later stage, the reduction rate becomes slow and decreases gradually to the end of the reduction. It is also observed that the reduction of PTC by coal depends greatly on the temperature. At high temperatures, the reduction degree reaches high values faster and the final value achieved is higher than at low temperatures. The final phase composition of the reduced PTC-coal briquette consists in iron and ferrous-pseudobrookite (FeTi₂O₅), while Fe_2.75Ti_0.25O₄, Fe_2.5Ti_0.5O₄, Fe_2.25Ti_0.75O₄, ilmenite (FeTiO₃) and wustite (FeO) are intermediate products. The reaction rate is controlled by the phase boundary reaction for reduction degree less than 0.2 with an apparent activation energy of about 68 kJ·mol?1 and by three-dimensional diffusion for reduction degree greater than 0.75 with an apparent activation energy of about 134 kJ·mol?1. For the reduction degree in the range of 0.2–0.75, the reaction rate is under mixed control, and the activation energy increases with the increase of the reduction degree.     

Description of mechanism function about dehydration of cobalt oxalate dihydrate by multiple rates isotemperature method

0　IntroductionThetechnologyofthermalanalysishasbeenwidelyusedinthestudyofthermalbehaviorandthermalcharacterofsolidstatereaction ,theprimaryintentionofthermalanalysiskineticsistoestablishseparatevaluesofapparentactivationenergyE ,themostprobablemechanism g(α)andthepre exponentialfactorA ,meanwhilethedeterminationofg(α)hasgraduallybeenthefocusofthisfield .Inthisfield ,therearemostlygeneralkineticsmethodsused presently ,suchasCoats Redfern’s[1 ] integralmethod ,Achar’s[2 \〗differentialmet…     

碱式碳酸锌在二氧化碳气氛下的热分解动力学

运用TG/SDTA同步分析仪, 研究了碱式碳酸锌在流动二氧化碳气氛中的热分解过程及热分解动力学. 探讨了加热速率对反应过程的影响. 采用Friedman法对实验数据进行分析,结果表明,反应的活化能数值随着分解率的不同而变化, 由此推断该反应是由多步反应组合而成的,其平均表观活化能E_a为286.84 kJ/mol.     

Application of an Optical Biosensor to Study the Interaction between Porphyrins and Wheat Germ Agglutinin

0Introduction Porphyrinderivativeshavebeenusedasphotosensitizersinphotodynamictherapy(PDT),anewapproachdevel opedforthetreatmentofcancer[1].Cationwater solublepor phyrinsareofconsiderableinterestowingtotheirpossiblebio medicalapplications[2].Inwhich,theinhibiteffectonthe growthmetabolismofE.coliandcancercellHL60ofmeso tetra(4N ethylacetatepyridyl)porphyrin(H2NEAE pp)and itsZn(Ⅱ)complexform(ZnNEAE pp)havebeenrecentlyin vestigated[3,4].Toenhancetumor locationandanticancerac tivitiesofdr…     

Kinetic study on the direct nitridation of silicon powders diluted with α-Si3N4 at normal pressure

Silicon nitride (Si₃N₄) powders were prepared by the direct nitridation of silicon powders diluted with α-Si₃N₄ at normal pressure. Silicon powders of 2.2 μm in average diameter were used as the raw materials. The nitriding temperature was from 1623 to 1823 K, and the reaction time ranged from 0 to 20 min. The phase compositions and morphologies of the products were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The effects of nitriding temperature and reaction time on the conversion rate of silicon were determined. Based on the shrinking core model as well as the relationship between the conversion rate of silicon and the reaction time at different temperatures, a simple model was derived to describe the reaction between silicon and nitrogen. The model revealed an asymptotic exponential trend of the silicon conversion rate with time. Three kinetic parameters of silicon nitridation at atmospheric pressure were calculated, including the pre-exponential factor (2.27 cm·s^?1) in the Arrhenius equation, activation energy (114 kJ·mol^?1), and effective diffusion coefficient (6.2×10^?8 cm²·s^?1). A formula was also derived to calculate the reaction rate constant.     

Effect of CO<Subscript>2</Subscript> and H<Subscript>2</Subscript>O on gasification dissolution and deep reaction of coke

To more comprehensively analyze the effect of CO₂ and H₂O on the gasification dissolution reaction and deep reaction of coke, the reactions of coke with CO₂ and H₂O using high temperature gas-solid reaction apparatus over the range of 950-1250℃ were studied, and the thermodynamic and kinetic analyses were also performed. The results show that the average reaction rate of coke with H₂O is about 1.3-6.5 times that with CO₂ in the experimental temperature range. At the same temperature, the endothermic effect of coke with H₂O is less than that with CO₂. As the pressure increases, the gasification dissolution reaction of coke shifts to the high-temperature zone. The use of hydrogen-rich fuels is conducive to decreasing the energy consumed inside the blast furnace, and a corresponding high-pressure operation will help to suppress the gasification dissolution reaction of coke and reduce its deterioration. The interfacial chemical reaction is the main rate-limiting step over the experimental temperature range. The activation energies of the reaction of coke with CO₂ and H₂O are 169.23 kJ·mol-1 and 87.13 kJ·mol-1, respectively. Additionally, water vapor is more likely to diffuse into the coke interior at a lower temperature and thus aggravates the deterioration of coke in the middle upper part of blast furnace.     

硫酸钛催化酯化反应动力学研究

根据硫酸钛催化合成乙酸正丁酯反应的特点导出非等温变体积条件下的反应速率方程,并导出用于计算动力学参数的理论公式。在此基础上对不同实验条件下的多组实验数据进行动力学处理,结果表明该反应服从二级反应动力学模型,表观活化能为１９７．９４ｋＪ·ｍｏｌ－１,指前因子为４．２６５１×１０２５ｄｍ３·ｍｏｌ－１·ｍｉｎ－１．     

Standard molar enthalpy of formation of morin studied by rotating-bomb combustion calorimetry

Flavonols are plant pigments that are ubiquitous in nature. Morin and other related plant flavonols have come into recent prominence because of their usefulness as anticancer, anti-tumor, anti-AIDS, and other important therapeutic activities of significant potency and low systemic toxicity. The heat of combustion of morin (molecular formula, C₁₅H₁₀O₇·H₂O) in oxygen was measured by a rotating-bomb type combustion calorimeter, the standard molar enthalpy of combustion of morin at T = 298.15 K was determined to be Δ_c H _m^⦵ (C₁₅H₁₀O₇·H₂O, s) = −(5 937.99 ± 2.99) kJ · mol⁻¹. The derived standard molar enthalpy of the formation of morin in solid powder state at T = 298.15 K, Δ_f H _m^⦵ (C₁₅H₁₀O₇·H₂O, s), was −(1 682.12 ± 3.58) kJ · mol⁻¹, which provide an accurate data of the stability of morin to the pharmacy and pharmacology. Biography: HOU Hanna(1956–), female, Visiting researcher, Associate professor of Hubei University of Education, research direction: thermochemistry.     

Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

The concentration of atmospheric CO₂ in Beijing increased rapidly at a mean growth rate of 3.7% · a⁻¹ from 1993 to 1995. After displaying a peak of (409.7±25.9) μmol · mol⁻¹ in 1995, it decreased slowly. Both the almost stable anthropogenic CO₂ source and increasing biotic CO₂ sink contribute to the drop of CO₂ concentration from 1995 to 2000. The seasonal variation of CO₂ concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) μmol · mol⁻¹, and a minimum in summer, averaging (369.1±6.1) μmol·mol⁻¹. The seasonal variation of CO₂ concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO₂ concentration for a year in Beijing is highly clear: daily maximum CO₂ concentration usually occurs at night, but daily minimum CO₂ concentration does in the daytime, with a mean diurnal difference more than 34.7 μmol·mol⁻¹. It has been revealed that the interannual variations of atmospheric CO₂ concentration in winter and autumn regulated the interannual trend of atmospheric CO₂, whereas the interannual variation of CO₂ concentration in summer affected the general tendency of atmospheric CO₂ in a less degree.     

Study on the viscoelastic behavior of SEEPS block copolymer based on a modified BSW model

Studies on the viscoelastic behavior of styrene[ethylene-（ethylene-propylene）] -styrene block copolymer （SEEPS） were carried out, and some characteristic viscoelastic parameters were calculated. The longest relaxation time was obtained through simulating the relaxation spectrum on the basis of a modified Baumgaertel-SchausbergerWinter （mBSW） model. The results revealed that there exists a “second plateau” in the low frequency region of the master curves. The reason for this phenomenon is attributed to the entanglement of macromolecular chains. It is suggested that the hard blocks, polystyrene, act as entanglement points, resulting in a topology restraint to the movement of macromolecular chains. Meanwhile, it is found that the horizontal shift factors （aT） vs temperature in the master curve could be fitted to the WiUiams-Landel-Ferry （WLF） equation and Arrhenius equation respectively and the flow activation energy （Ea） is 127.88 kJ/mol. In addition, the plateau modulus （GN） and entanglement molecule weight （Me） were calculated.     

催化H2O2氧化吖啶黄固体基质室温磷光法测定痕量秋水仙碱

基于秋水仙碱(COL)能催化过氧化氢(H_2O_2)氧化吖啶黄(AY)的反应,导致AY的室温磷光信号(RTP)剧烈猝灭,据此建立了超灵敏催化H2O2氧化AY固体基质室温磷光法(SS-RTP)测定COL的新方法。此方法的量化限(LOQ)为0.12 fg/斑(对应浓度为3.1×10–13 g·m L–1),灵敏度高、简便、快捷、准确。用于血清中COL的测定,结果与UPLC-MS/MS相吻合。同时测定了动力学常数,其活化能(E)为40.53 k J·mol~(–1),速度反应常数(k)为3.97×10~(–4)·s~(–1)。     

Synthesis, Characterization and Calorimetry of Ni（C4H8N2O3）2Cl2

A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine（GG）. It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni（C4HsN2O3）2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni（GG）2Cl2（solid） has been determined to be -（1 674.66±2.02） kJ · mol^-1 at 298.15 K.