Visible light photocatalytic decoloration of methylene blue on novel N-doped TiO2

Novel N-doped TiO2 (denoted as N-NTA600) was prepared by treating nanotube titanic acid (NTA) in NH3 flow. Its visible light photocatalytic activity,evaluated by decoloration reaction of methylene blue,is higher than that of N-P25(600) prepared by treatment of P25-TiO2 in the same condition. It is suggested that the origin of visible-light photocatalytic activity is single-electron-trapped oxygen vacancy (Vo·) modified by chemisorbed NO.     

Catalysis of organic pollutant photodegradation by metal phthalocyanines immobilized on TiO<Subscript>2</Subscript>@SiO<Subscript>2</Subscript>

A TiO2@SiO2 hybrid support was prepared by the sol-precipitation method using n-octylamine as a template.The photocatalyst manganese phthalocyanine tetrasulfonic acid (MnPcS) was immobilized on the support to form MnPcS-TiO2@SiO2.X-ray diffraction (XRD) and UV-Visible diffuse reflectance spectra (UV-Vis DRS) were employed to characterize the catalyst.The photocatalytic degradation of rhodamine B (RhB) and the catalytic oxidation of o-phenylenediamine (OPDA) under visible light irradiation were used as probe reactions.The mineralization efficiency and the degradation mechanism were evaluated using chemical oxygen demand (COD Cr) assays and electron spin resonance (ESR),respectively.RhB was efficiently degraded by immobilized MnPcS-TiO2@SiO2 under visible light irradiation.Complete decolorization of RhB occurred after 240 min of irradiation and 64.02% COD Cr removal occurred after 24 h of irradiation.ESR results indicated that the oxidation process was dominated by the hydroxyl radical (·OH) and superoxide radical (O-·2) generated in the system.     

Investigation of the cross-reaction mechanism of C<Subscript>6</Subscript>H<Subscript>5</Subscript>F-HNO<Subscript>2</Subscript> aqueous solution irradiated at 355 nm by transient absorbance spectrum technique

The transient absorption spectrum technique was employed to investigate the cross-reaction mechanism of C6H5F-HNO2 aqueous solution irradiated at 355 nm. The characteristic and the kinetic parameters of transient species were also detected. Hydroxyl radical derived from the photolysis of HNO2 was added to monofluorobenzene with a second-order rate constant of （5.83±0.17）×10^9 L·mol^-1·s^-1 to form an adduct, C6H5F…OH, which was able to react with HNO2 as the main reaction pathway with a rate constant of （8.3±0.1）×10^7 L·mol^-1·s^-1. The C6F6…OH adduct can also be decayed by elimination of H2O to yield monofluorophenyl radical C6H4F-. By GC-MS technique, the final products were identified to be monofluorophenol, nitro-monofluorobenzene, nitro-monofluorophenol and para-fluorobiphenyl.     

Photocatalytic degradation of metronidazole in aqueous solution by niobate K<Subscript>6</Subscript>Nb<Subscript>10.8</Subscript>O<Subscript>30</Subscript>

The photocatalytic degradation of antibiotic metroni-dazole in aqueous solution by niobate K6Nb10.8O30 photocatalyst that was prepared using a soft-chemical method was studied by Fourier transform infrared spectroscopy and UV-Vis absorption spectrum. Metronidazole is very stable and is difficult to degrade under UV irradiation. K6Nb10.8O30 photocatalyst cannot degrade metronidazole without UV irradiation and shows very high photo-catalytic activity for the degradation of metronidazole under UV irradiation. The photocatalytic degradation rate of metronidazole increased with increasing the dosage of K6Nb10.8O30 photocatalyst. The photocatalytic degradation reaction of metronidazole by nio-bate K6Nb10.8O30 follows the first-order kinetic equation.     

Electrochemical performance of a nickel-rich LiNi<Subscript>0.6</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.2</Subscript>O<Subscript>2</Subscript> cathode material for lithium-ion batteries under different cut-off voltages

A spherical-like Ni_0.6Co_0.2Mn_0.2(OH)₂ precursor was tuned homogeneously to synthesize LiNi_0.6Co_0.2Mn_0.2O₂ as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi_0.6Co_0.2Mn_0.2O₂ were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge-discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi_0.6Co_0.2Mn_0.2O₂ material obtained by calcination at 900℃ displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh·g-1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh·g-1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh·g-1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively.     

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.     

自由基抑制剂对不同晶型TiO2光催化反应的影响

以荧光光谱法研究了不同晶型 TiO₂ 的光催化反应体系中羟基自由基(·OH)的产生情况,表明在H₂O₂存在条件下,金红石型 TiO₂ 经可见光激发可持续稳定产生·OH,而以锐钛矿型 TiO₂ 作光催化剂时,则检测不到·OH的生成。光催化结果表明,在H₂O₂存在条件下,苯酚可被 TiO₂ 可见光催化降解;往反应体系加入自由基抑制剂(叔丁醇或甲醇)时,明显降低了金红石型 TiO₂ 的降解效率,但对锐钛矿型 TiO₂ 的影响较弱。以金红石型 TiO₂ 作光催化剂时,苯酚的降解反应主要发生在溶液中;而以锐钛矿型 TiO₂ 作光催化剂时,则苯酚的降解反应主要发生在催化剂的表面。     

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, characterization and properties of ruthenium-substituted polyoxometallic acid H_6Ru(H_2O)FeW_(11)O_(39)·18H_2O with Keggin structure

The ruthenium-substituted polyoxometallic acid H6 [Ru(H2O)FeW 11O39 ]·18H2O was synthesized by stepwise acidification and stepwise addition of solutions of the component elements, and an ion-exchange-cooling method. The product was characterized using inductively coupled plasma spectrometry (ICP), Infrared Spectroscopy (IR), Ultraviolet Spectroscopy (UV), and X-ray diffraction (XRD). The results show that this complex has the Keggin structure. The determination of the thermal stability and proton conductivi...     

Near-infrared to visible up-conversion emissions of Er^3＋ doped Al2O3 powders derived from the sol-gel method

The Er3 doped Al2O3 powders were prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3.5H2O]. The different phase structure, including three crystalline types of (Al,Er)2O3 phases, γ, θ, α, and two Er-Al-O phases, ErAlO3 and Al10Er6O24, was obtained with the 1 mol% Er3 doped Al2O3 powders at the different sintering temperatures of 600―1200℃. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3 , were detected by a 978 nm semiconductor laser diodes excitation. The phase structure and OH content had evident influence on the up-conversion emissions intensity. The maximum intensities of both the green and red emissions were obtained respectively for the Er3 doped Al2O3 powders sintered at 1200 ℃, which was composed mainly of α-(Al,Er)2O3, less of ErAlO3 and Al10Er6O24 phases, and with the least OH content. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er3 doped Al2O3 powders.     

Enhanced photocatalytic degradation of tetracycline hydrochloride by molecular imprinted film modified TiO<Subscript>2</Subscript> nanotubes

To enhance the photocatalytic activity of TiO2 nanotubes,tetracycline hydrochloride(TC) molecularly imprinted titania modified TiO2 nanotubes(MIP-TiO2) was prepared by liquid phase deposition,which improved the molecular recognition ability of the photocatalyst toward template molecules.This MIP-TiO2 photocatalyst was characterized by ESEM and XRD,which showed that the imprinted titania was deposited on the nanotube uniformly and was of well-crystalized anatase-type.In the adsorption experiments,MIP-TiO2 exhibited a high adsorption capacity(about 1.6 times higher than that of TiO2 nanotubes) for TC mainly because of its imprinted sites and high surface area.Under UV irradiation MIP-TiO2 showed enhanced photocatalytic activity with an apparent first-order rate constant 1.9-fold that of TiO 2 nanotubes.     

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.     

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.     

TiO2/SiO2纳米粒子光催化降解庚烯/二氧化硫

以TiO₂/SiO₂纳米粒子为催化剂， 研究了催化剂不同焙烧温度对二氧化硫与庚烯光催化反应的影响. 结果表明， 经600 ℃焙烧的催化剂对庚烯的降解最好. 同时研究了庚烯和二氧化硫的初始浓度、 氧气和水蒸气的不同含量及光强等因素对其光催化氧化降解的影响. 庚烯的降解速率随着二氧化硫浓度的增加而增加， 最终趋于稳定. 在二氧化硫浓度一定时， 庚烯的反应速率分别随着氧气和水分子含量的增加而不断增大， 氧含量为20%时速率最大； 水分子含量为444 μmol/L时速率最大. 庚烯的反应速率随着光强的增加而增大， 光强增至8.32 mW/cm²时， 反应速率趋于定值. 通过FT-IR和GC-MS测定初步确定了反应产物.     

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…     

Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>

An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using (NH₄)₂SO₄. The optimized reaction conditions are defined as an (NH₄)₂SO₄/zinc molar ratio of 1.4:1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of (NH₄)₂SO₄/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric–differential thermal analysis was used for (NH₄)₂SO₄ and zinc mixed in a molar ratio of 1.4:1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle–Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained.     

Phase transformation and crystal growth behavior of 8mol% (SmO<Subscript>1.5</Subscript>, GdO<Subscript>1.5</Subscript>, and YO<Subscript>1.5</Subscript>) stabilized ZrO<Subscript>2</Subscript> powders

Nanocrystalline powders of ZrO₂-8mol%SmO_1.5(8SmSZ), ZrO₂-8mol%GdO_1.5 (8GdSZ), and ZrO₂-8mol%YO_1.5(8YSZ) were prepared by a simple reverse-coprecipitation technique. Differential thermal analysis/thermogravimetry (DTA/TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM) were used to study the phase transformation and crystal growth behavior. The DTA results showed that the ZrO₂ freeze-dried precipitates crystallized at 529, 465, and 467℃ in the case of 8SmSZ, 8GdSZ, and 8YSZ, respectively. The XRD and Raman results confirmed the presence of tetragonal ZrO₂ when the dried precipitates were calcined in the temperature range from 600 to 1000℃ for 2 h. The crystallite size increased with increasing calcination temperature. The activation energies were calculated as 12.39, 12.45, and 16.59 kJ/mol for 8SmSZ, 8GdSZ, and 8YSZ respectively.     

The giant magnetocaloric effect in Gd<Subscript>5</Subscript>Si<Subscript>2</Subscript>Ge<Subscript>2</Subscript> with low purity gadolinium

The giant magnetocaloric effect Gd5Si2Ge2 alloy was prepared with 99wt% low purity commercial Gd. Powder XRD and magnetic measurements showed that the Gd5Si2Ge2 alloy annealed at 1200℃ for 1h had a significant magnetic- crystallographic first order phase transition at about 270 K. The maximal magnetic entropy change is 17.55 J· kg^-1· K^-1 under a magnetic field change of 0-5 T. The distinct increase of magnetic entropy change belongs to the first-order phase transition from the orthorhombic Gd5Si4-type to the monoclinic Gd5Si2Ge2-type after high temperature heat-treatment.     

Electrochemical properties of LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.3</Subscript>Ti<Subscript>0.2</Subscript>O<Subscript>4</Subscript>/Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> cells

Spinel compounds LiNi_0.5Mn_1.3Ti_0.2O₄ (LNMTO) and Li₄Ti₅O₁₂ (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g⁻¹ at 0.2C and 118.2 mA·h·g⁻¹ at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.     

Lithium-ion full cell with high energy density using nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode and SiO-C composite anode

A high-energy-density Li-ion battery with excellent rate capability and long cycle life was fabricated with a Ni-rich layered LiNi_0.8Mn_0.1Co_0.1O₂ cathode and SiO-C composite anode. The LiNi_0.8Mn_0.1Co_0.1O₂ and SiO-C exhibited excellent electrochemical performance in both half and full cells. Specifically, when integrated into a full cell configuration, a high energy density (280 Wh·kg-1) with excellent rate capability and long cycle life was attained. At 0.5C, the full cell retained 80% of its initial capacity after 200 charge/discharge cycles, and 60% after 600 cycles, indicating robust structural tolerance for the repeated insertion/extraction of Li+ ions. The rate performance showed that, at high rate of 1C and 2C, 96.8% and 93% of the initial capacity were retained, respectively. The results demonstrate strong potential for the development of high energy density Li-ion batteries for practical applications.