用碘化铵活化光谱法连续测定多元素

用碘化铵为活化剂降低化探样品中多元素的活化能 ,使其在氩气氛围中形成稳定、小背景的激发状态 ,再通过目视谱线强度比较法 ,连续测定化探样品中Sb、As、Pb、Cu、Bi、Mo、Ag、Zn。该方法可以替代原子荧光、原子吸收和极谱 3种综合分析方法 ,对标样GBW0 74 0 1和GBW0 74 0 3的 8种元素平行测定 4次 ,相对标准偏差小于 2 7%。

Tannins from Canarium album with potent antioxidant activity

The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） and nuclear magnetic resonance （NMR） analyses The results show the predominance of signals representative of procyanidins and prodelphinidins. In addition, epicatechin and epigallocatechin polymers with galloylated procyanidin or prodelphinidin were also observed. The tannins were screened for their potential antioxidant activities using l,l-diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing/antioxidant power （FRAP） model systems. Tannins extracted from leaves, twigs and stem bark all showed a very good DPPH radical scavenging activity and ferric reducing power.

Characteristics of coal re-oxidation based on microstructural and spectral observation

In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining,scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructure and chemical reaction of functional groups of eight coal samples at different ranks.Result shows that after initial oxidation,the surface morphology of pore are different,and the porosity of coal is increased and the oxygen adsorption capacity of coal is improved.The change of coal molecular structure and presence of a large amount of active oxygen-containing functional groups lead to increasing tendency of coal to further oxidation.In addition,the higher lever of the initial oxidation is,the easier the re-oxidation occurs.

Industrial Production of Catalyst for Removing Trace Olefins from Aromatics

A novel additive incorporated into the catalyst for removing trace olefins from aromatics was proposed, and under the laboratory conditions the lifetime of the catalyst was increased from 5 h to 8 h upon specifying the conversion of the olefins equating to more than 55% as a criterion. Catalyst production, which was named ROC, has been successfully scaled up from laboratory formulations to commercial scale manufacture and over 100 tons of catalyst had been produced. The superiority in catalytic activity was identified by the evaluation tests of the ROC catalyst based on whatever kind of feedstocks (with their bromine index ranging from 400 mgBr/100g to 1 200 mgBr/100g) being used as the feedstock. The X-ray diffraction patterns had verified that the additive was highly dispersed on the surface of catalyst; the GC-FID analysis results showed that the ROC catalyst could increase the xylene content; the pyridine-FTIR spectroscopic analyses suggested that the additive could increase the amount of the weak L acids, which was the main cause leading to enhancement of the catalyst activity.

Homogeneous Oxidative Coupling Catalysts： Reactivity of [（Pyr）nCuX]4O2 with Carbon Dioxide to Generate New Active Initiators [（Pyr）nCuX]4（CO3）2 （n = 1 or 2, X = Cl, Br or I, Pyr = Pyrrolidine）

This paper represents the interaction of well characterized Lewis base [（Pyr）nCuX]4O2, n = 1 or 2, X = Cl, Br or I, Pyr = pyrrolidine with CO2 as a Lewis acid to produce new series of oxidative coupling and catechol oxidase initiators [（Pyr）nCuX]4（CO3）2. These carbonato derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH2Cl2 or PhNO2. Cryoscopic measurements support tetranuclear core structure for all of them. Infrared spectra show differences from their oxo analogous in the carbonato domains but those differences did not distinguish between tridentate bridging carbonato and bidentate one. Rate of oxidation of 2,6-dimethylphenol （DMP） by [（Pyr）CuCl]4（CO3）2, supports coordination number six for Cu（Ⅱ） centers in [（Pyr）CuCl]4（CO3）2. In order to fulfill coordination number six, for n = 1, carbonate will act as tridentate while for n = 2, it will act as bidentate, as shown in Scheme 4. Near infrared spectra indicate a [（3 halo） Cu（Ⅱ） charge transfer] for [（Pyr）nCuX]4（CO3）2, n = 1 or 2, X = Cl or Br. Low molecular absorptivities of the maxima at 825 nm and 730 nm for [（Pyr）nCuI]4（CO3）2, n = 1 or 2 with a minimum of high molecular absorptivities at 600 nm, comparing to X= CI or Br analogous, support a step structure for [（Pyr）,Cul]4（CO3）2, as shown in Scheme 5. Cyclic voltammograms for [（Pyr）nCuX]4（CO3）2; n = 1 or 2, X = CI or Br, are irreversible in characters.

Catalytic performance and kinetics of Au/γ-Al_2O_3 catalysts for low-temperature combustion of light alcohols

Au/γ-Al2O3 catalysts were prepared by deposition-precipitation method for the catalytic combustion of low concentration alcohol streams(methanol,ethanol,iso-propanol and n-propanol).The catalysts were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffractometry(XRD) and energy dispersive X-ray micro analysis(EDS) techniques.The XPS results showed that there was only Au0 on the surface of catalysts.The XRD patterns showed that Au was presumably highly dispersed over γ-Al2O3.The temperatures for complete conversion of methanol,ethanol,iso-propanol and n-propanol with concentration of 2.0 g/m3 were 60,155,170 and 137 ℃,respectively,but they were completely mineralized into CO2 and H2O at 60,220,260 and 217 ℃ respectively over the optimized catalyst.The activity of the catalyst was stable in 130 h.The kinetics for the catalytic methanol elimination followed quasi-first order reaction expressed as r=0.652 8c0+0.084 2.The value of apparent activation energy is 54.7 kJ/mol in the range of reaction temperature.

Biosorption of basic violet 10 onto activated Gossypium hirsutum seeds:Batch and fixed-bed column studies

Sulphuric acid activated immature Gossypium hirsutum seed(AIGHS) was prepared to biosorbe basic violet 10(BV10) from aqueous solutions.Methylene blue number,iodine number and Brunauer-Emmett-Teller surface analysis indicated that the AIGHS were hetero-porous.Boehm titrations and Fourier-transform infrared spectra demonstrated the chemical heterogeneity of the AIGHS surface.Batch biosorption studies were used to examine the effects of process parameters in the following range:pH 2-12,temperature 293-313 K,contact time 1-5 h and initial concentration 200-600 mg·L^(-1).The matching of equilibrium data with the Langmuir-Freundlich form of isotherms indicated that the BV10 was adsorbed via chemisorption and pore diffusion.Kinetic investigation indicated multiple order chemisorption through an Avrami kinetic model.Film diffusion controlled the rate of BV10 biosorption onto AIGHS.The spontaneous and endothermic nature of sorption was corroborated by thermodynamic study.Continuous biosorption experiments were performed using a fixed-bed column and the influence of operating parameters was explored for different ranges of initial concentration 100-300 mg·L^(-1),bed height 5-10 cm,and flow rate 2.5-4.5 ml·min^(-1).A dose response model accurately described the fixed-bed biosorption data.An external mass transfer correlation was formulated explaining BV10-AIGHS sorption.

Geochemical Assessment of Heavy Metals in Surface Sediments： A Case Study of the Tema Port, Ghana

Ten trace and heavy metals （Fe, Mn, Ni, Zn, Cu, Cd, As, Co, Cr and V） were analysed in sediments collected from nine stations at the Tema Port of Ghana, during the dry and wet seasons. Analysis of samples was done using INAA （instrumental neutron activation analysis） for Mn, V, Cu, As and Cd, and AAS （atomic absorption spectrophotometry） for Fe, Cr, Zn, Ni and Co. The concentrations of metals in sediments followed the orders Fe 〉 V〉 Mn 〉 Cd 〉 Ni 〉 Zn 〉 Cu 〉As, for the dry season and Fe 〉 V 〉 Ni 〉 Cu 〉 Zn 〉 Mn 〉 Cd 〉As, for the wet season. Concentrations of Co and Cr were below detection limit, whiles Cu, Cd and Ni were found to be above the TELs （threshold effect levels） of NOAA＇s （National Oceanic and Atmospheric Administration＇s） SQuiRTs （screening quick reference tables） at most sites. Estimated enrichment factors for individual metals showed very high contamination of the port＇s sediments, with Cd occurring at all sites, and Cu, As, V and Ni occurring at some sites for both dry and wet seasons. Although sediments from the Tema Port were highly enriched with Cd, Cu, Ni and V above natural background levels, the overall PLI （pollution load index） per sampling station considering background values of the analysed elements indicated that metal pollution in the port＇s sediment is below 1, indicating relatively unpolluted sediment.

Study on Activated Bentonite Applied to tert-Butylation of Toluene

tert-Butylation of toluene with tert-butanol used as the alkylating agent was investigated over the activated bentonite and HY zeolite used as the catalyst.The influences of various butylation reaction parameters,including the toluene/tert-butanol ratio,the reaction temperature,and the space velocity were discussed.The optimal results were obtained at a reaction temperature of 180 ℃,a space velocity of 4 h-1,and a mole ratio of toluene to tert-butanol equating to 2.The structure and acidic properties of catalyst were characterized by the BET method and the Fourier transform infrared (FTIR) spectroscopy.Compared with the HY zeolite,the activated bentonite possessed high activity for toluene conversion and high para-selectivity because it had larger pore diameter,smaller micropore surface area and higher ratio of total Lewis acids to total Br nsted acids.

Synthesis and Antimicrobial Activity of Heterocyclic Compounds Containing Chromene Ring

Synthesis of some new compounds containing chromene ring are described in this work. They were synthesized in moderate to good yield, started with Condensation of 7-hydroxy-4-methylcoumarin （1） with ethyl bromoacetate furnishes ethyl-2-（4-methyl-2-oxo-2H-chromen-7-yloxy） acetate （2）. The structures of all the new compounds were confirmed using IR, 1H-NMR spectra and micro analysis, selected members of the synthesized compound were screened for antimicrobial activity. They have shown a wide range of activity from one completely inactive compound to medium active ones.

Two new compounds with microporous constructed by Waugh-type polyoxoanion and transition metal ions

Two new compounds with microporous Co3[MnMo9O32].15H2O(1) and Cu3[MnMo9O32].15H2O(2) have been synthesized,and characterized by IR,element analysis,TG and single-crystal X-ray analysis.The structure analyses reveal that compounds 1 and 2 are isostructural.In crystal,the Waugh-type polyoxoanions [MnMo9O32]6-are connected by Co2+ or Cu2+ cations to a 3D open-framework,which possesses channels along the [1 2 2] direction of approximately 8.27 × 11.97 .The photocatalytic performances of compounds 1 and 2 for photodegradation of RhB with UV irradiation have been studied,which show a good photocatalytic activity for photodegradation of RhB.

A High Performance Cobalt-Doped ZnO Visible Light Photocatalyst and Its Photogenerated Charge Transfer Properties

Highly photocatalytically active cobalt-doped ZnO （ZnO：Co） nanorods have been prepared by a facile hydrothermal process. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and UV-vis diffuse reflectance spectroscopy confirmed that the dopant ions substitute for some of the lattice zinc ions, and furthermore, that Co〉 and Co〉 ions coexist. The as-prepared ZnO：Co samples have an extended light absorption range compared with pure ZnO and showed highly efficient photocatalytic activity, only requiring 60 rain to decompose -93% of alizarin red dye under visible light irradiation （λ 〉 420 nm）, The photophysical mechanism of the visible photocatalytic activity was investigated with the help of surface photovoltage spectroscopy. The results indicated that a strong electronic interaction between the Co and ZnO was present, and that the incorporation of Co promoted the charge separation and enhanced the charge transfer ability and, at the same time, effectively inhibited the recombination of photogenerated charge carriers in ZnO, resulting in high visible light photocatalytic activity.

Generation and Photocatalytic Activities of Bi@Bi2O3 Microspheres

Composite Bi@Bi2O3 microspheres have been synthesized via a microwave-assisted solvothermal route. The Bi@Bi2O3 microspheres had a narrow size distribution in the range 1.2-2.8 mm. Glucose was selected as the reductant, BiCl3 as the bismuth source, and ethylene glycol （EG） as the solvent in the synthesis system. The as-synthesized sample was characterized by X-ray diffraction （XRD）, Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, particle diameter distribution, energy dispersive X-ray spectroscopy （EDS）, ultraviolet-visible （UV-vis） spectroscopy, and photoluminescence （PL） spectroscopy. The photocatalytic activities of the Bi@Bi2O3 microspheres were evaluated by the photodegradation of rhodamine B （RhB） and methyl orange （MO） dyes under UV light irradiation. The degradation reached -96.6% for RhB and 100% for MO after 4 h reaction in the presence of the as-synthesized Bi@Bi2O3 microspheres.

Enhanced electro-oxidation of formic acid by a PdPt bimetallic catalyst on a CeO_2-modified carbon support

PdPt bimetallic catalysts that employ CeO2-modified carbon black as a support have been prepared using an organic colloidal method. PdPt/CeO2-C shows excellent performance toward the anodic oxidation of formic acid. The effects of varying both Pd to Pt ratio and CeO2 content have been investigated. The optimal Pd to Pt atomic ratio is 15, indicating that addition of small amounts of Pt can significantly enhance the activity of the catalyst. When the CeO2 content in the catalyst reaches as high as ~15 wt.%, the catalyst shows the maximum activity. Adding CeO2 not only enhances the catalytic activity of the material, but may also change the mechanism of its catalysis of the anodic oxidation of formic acid. PdlsPh/15CeO2-C exhibited 60% higher activity than Pd/C, and had a negative shift in onset potential of more than 0.1 V. Based on characterization by X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis and transmission electron microscopy, the interactions between the components are revealed and discussed in detail.

Synthesis of Ag-SiO_2 composite nanospheres and their catalytic activity

A simple,mild,and time-saving method is employed to synthesize Ag-SiO2 composite nanospheres with Ag nanoparticles uniformly distributed on the surface of SiO2 nanoparticles.The chemical elements and the morphology of Ag-SiO2 composite nanospheres were analyzed with transmission electron microscopy(TEM),X-ray power diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).On the surface of Ag-SiO2 composite nanospheres,silane coupling agent(KH-550)is introduced as an intermediary to connect the surfaces of SiO2 nanospheres and Ag nanoparticles,which is also helpful for avoiding the aggregation of Ag nanoparticles.It is found that Ag-SiO2 composite nanospheres have very good catalytic properties for the reduction of organic dyes,which may have potential application in wastewater treatment.

Functionalized, carbon nanotube material for the catalytic degradation of organophosphate nerve agents

Recent world events have emphasized the need to develop innovative, functional materials that will safely neutralize chemical warfare （CW） agents in situ to protect military personnel and civilians from dermal exposure. Here, we demonstrate the efficacy of a novel, proof-of-concept design for a Cu-containing catalyst, chemically bonded to a single-wall carbon nanotube （SWCNT） structural support, to effectively degrade an organophosphate simulant. SWCNTs have high tensile strength and are flexible and light-weight, which make them a desirable structural component for unique, fabric-like materials. This study aims to develop a self-decontaminating, carbon nanotube-derived material that can ultimately be incorporated into a wearable fabric or protective material to minimize dermal exposure to organophosphate nerve agents and to prevent accidental exposure during decontamination procedures. Carboxylated SWCNTs were functionalized with a polymer, which contained Cu-chelating bipyridine groups, and their catalytic activity against an organophosphate simulant was measured over time. The catalytically active, functionalized nanomaterial was characterized using X-ray fluorescence and Raman spectroscopy. Assuming zeroth-order reaction kinetics, the hydrolysis rate of the organophosphate simulant, as monitored by UV-vis absorption in the presence of the catalytically active nanomaterial, was 63 times faster than the uncatalyzed hydrolysis rate for a sample containing only carboxylated SWCNTs or a control sample containing no added nanotube materials.