铋铁复合氧化物光催化材料的制备及其性能研究

采用共沉淀法制备了一系列铋铁复合氧化物光催化剂,并以可见光降解甲基橙为模型反应,研究其在可见光照射下降解甲基橙的光催化性能。详细考察了p H值、铋铁摩尔比、煅烧温度等对其光催化性能的影响。在优化条件下,铋铁摩尔比为2∶1、p H=3~4时制备出的样品具有较好的光催化性能,甲基橙的降解率可达到91.95%。     

基于Fe3O4 纳米颗粒修饰膜固定尿素酶与谷脱氢酶的尿素传感器

将Fe3O4纳米粒子吸附于涂有壳聚糖(CH)膜的铟锡氧化物导电玻璃(ITO)上,获得Fe3O4纳米粒子-壳聚糖膜修饰电极,再将脲酶(Ur)和谷氨酸脱氢酶(GLDH)通过静电吸附固定在复合物膜上制备了尿素传感器.运用红外光谱、电子显微镜对传感膜的结构进行了表征;以制备的双酶电极为工作电极,采用微分脉冲伏安法研究了酶电极对尿素的响应,结果表明Ur-GLDH/CH-Fe3O4/ITO生物电极的峰电流对尿素非常敏感,尿素的质量浓度与峰电流分别在5 ～40 mg/L和60 ～100 mg/L范围内呈线性相关,检出限为0.5 mg/L .固定酶的米氏常数Km为0.56 mmol/L,该值较小,表明混合酶(Ur-GLDH)和尿素具有较好的亲和性.在CH-Fe3O4膜中,Fe3O4纳米粒子的引入增加了壳聚糖膜的表面积,增强了电极的电子传递;CH具有生物相容性,有利于保持生物酶活性.     

Water Interaction with Iron Oxides

We present a mechanistic study on the interaction of water with a well‐defined model Fe₃O₄(111) surface that was investigated by a combination of direct calorimetric measurements of adsorption energies, infrared vibrational spectroscopy, and calculations bases on density functional theory (DFT). We show that the adsorption energy of water (101 kJ mol⁻¹) is considerably higher than all previously reported values obtained by indirect desorption‐based methods. By employing ¹⁸O‐labeled water molecules and an Fe₃O₄ substrate, we proved that the generally accepted simple model of water dissociation to form two individual OH groups per water molecule is not correct. DFT calculations suggest formation of a dimer, which consists of one water molecule dissociated into two OH groups and another non‐dissociated water molecule creating a thermodynamically very stable dimer‐like complex.     

Specific Features of BiFeO3 Formation in a Mixture of Bismuth(III) and Iron(III) Oxides

Active formation of BiFeO₃ was observed at temperatures exceeding the temperature limit of its stability. The process mechanism was elucidated.     

Mixed Bismuth and Titanium Oxides obtained by thermolysis of hydroxide coprecipitates

By thermolysis of hydroxide coprecipitates of Bi(III) and Ti(IV) at medium temperatures between 500 and 660° one has obtained the following mixed bismuth and titanium oxides: Ti₈TiO₁₄, Bi₂TiO₅, Bi₄Ti₃O₁₂ and Bi₂Ti₃O₉. The hydroxide coprecipitates were obtained in controlled conditions, starting from Bi(No₃)₃ and TiO(No₃)₂. The thermolysis of the coprecipitates and the formation of mixed oxidic phases were investigated by means of TGA, TDA. IR and X-rays analysis.     

微电流作用下铁片置换海绵铋粉

针对铁粉置换沉积海绵铋所得铋粉品位较低的缺点,本工艺采用铁片置换海绵铋,铁片为阳极,石墨为阴极,直流微电流作用,电流密度5×10-3 A/cm2,温度40℃,所得海绵状铋粉品位在90％以上.通过置换过程的宏观动力学研究表明,其置换过程符合一级反应速率规律,活化能Ea=13.72 kJ/mol,反应速率方程为v=3.2470 ×c(Bi3+)exp(-13720/RT),置换过程的控制步骤为扩散控制.电化学分析结果显示,微电流作用很好的促进了置换过程,且置换海绵状铋粉品位高,杂质少,尤其铅含量明显降低.     

EPR Spectra of Modified Iron Oxides

Experimental data on gas-phase hydrogenation of several alkylbenzenes (toluene, ethlylbenzene, o-, m-, p-xylenes, mesitylene) over nickel catalyst are summarized. Rate dependence as a function of the chemical nature of substituent and position in the aromatic ring is discussed. The stereochemical distribution for dialkylbenzene and trialkylbenzene is addressed.     

Synthesis of Iron(II,III)-containing Derivatives of Arabinogalactan

A synthesis of iron(II, III) derivatives of arabinogalactan, involving formation in an alkaline solution of a hydrated iron(II, III) oxide biopolymer, is proposed. Optimal conditions of the synthesis are determined.     

Reaction of Thioxanthylium Cation with Pharmacophoric Heterocyclic Amines

Russian Journal of Organic Chemistry - Reactions of thioxanthylium tetrafluoroborate with pharmacophoric heterocyclic amines, pyrimidin-2-amine, 4,6-dimethylpyrimidin-2-amine,...     

Synthesis of Mesostructured Iron Oxides with Potential As(V) Adsorption Application

Mesostructured iron oxides(MIOs) were nanocasted from a plugged hexagonal templated silica(PHTS) with a Brunauer-Emmett-Teller(BET) surface area of 694 m²/g. Results of X-ray diffraction(XRD), transmission electron microscopy(TEM) and N₂ adsorption-desorption suggest that the nanocasted MIOs are synthetic hematite(α-Fe₂O₃) with a wormhole-like mesoporous network. As(V) adsorption test shows that the selected MIO—MIO-500(calcinated at 500℃) with a BET surface area of 82 m²/g has a maximum adsorption capacity of 5.39 mg/g for As(V), which is 2.5 times as large as that of natural hematite adsorbent. The study suggests that MIOs could be potentially used as the adsorbent of As(V) in wastewater.     

Arabinogalactan Poly- and Oligosaccharides Modified with 5-Aminosalicylic Acid

Arabinogalactan poly- and oligosaccharides from Siberian larch (Larix sibirica L.) were modified with 5-aminosalicylic acid. The chemical composition and certain physicochemical properties were studied. The optimal conditions for preparing the modified compounds were found. These compounds were demonstrated to possess anti-ulcer and anti-inflammatory activity in tests on experimental animals.__________Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 219–222, May–June, 2005.     

Propionic Anhydride Modification of Cellulosic Kenaf Fibre Enhancement with Bionanocarbon in Nanobiocomposites

The use of chemical modification of cellulosic fibre is applied in order to increase the hydrophobicity, hence improving the compatibility between the fibre and matrix bonding. In this study, the effect of propionic anhydride modification of kenaf fibre was investigated to determine the role of bionanocarbon from oil palm shell agricultural wastes in the improvement of the functional properties of bionanocomposites. The vinyl esters reinforced with unmodified and propionic anhydride modified kenaf fibres bio nanocomposites were prepared using 0, 1, 3, 5 wt% of bio-nanocarbon. Characterisation of the fabricated bionanocomposite was carried out using FESEM, TEM, FT-IR and TGA to investigate the morphological analysis, surface properties, functional and thermal analyses, respectively. Mechanical performance of bionanocomposites was evaluated according to standard methods. The chemical modification of cellulosic fibre with the incorporation of bionanocarbon in the matrix exhibited high enhancement of the tensile, flexural, and impact strengths, for approximately 63.91%, 49.61% and 54.82%, respectively. The morphological, structural and functional analyses revealed that better compatibility of the modified fibre–matrix interaction was achieved at 3% bionanocarbon loading, which indicated improved properties of the bionanocomposite. The nanocomposites exhibited high degradation temperature which signified good thermal stability properties. The improved properties of the bionanocomposite were attributed to the effect of the surface modification and bionanocarbon enhancement of the fibre–matrix networks.     

铁系复合氧化物催化性质的研究

合成出一系列La_(1-s)A′_sFeO_3(A′=Ca、Sr、Ba;0≤2≤1)复合氧化物催化剂,并研究了Ca、Sr、Ba部分取代La后催化剂对CO氧化活性的影响。以XRD测定其晶体结构。结果表明,除含Ca>0.5和Ba=1.0外均生成钙钛矿型结构。用XPS和TPD法研究了吸附性能。指认吸附氧是CO氧化的活性物种,并初步解释了活性规律的成因。     

Complex Iron Phosphate Anions and Their Salts as Products of Chemisorption of Phosphates by Crystalline Iron Oxides

Chemisorption of phosphate anions by crystalline iron oxides is confined to those sites of the sorbent surface where substitution of silicate (in hydrohematite) or hydroxo and aqua (in hydrogoethite) ligands by phosphate ions is possible. In these sites, new crystalline spherical entities were detected, which were able to pass into the liquid phase. The new formations were identified as ammonium salts of сomplex iron-phosphoric acids. Binding of ammonium cations from solution indicates that the primary phosphate chemisorption products are complex iron phosphate anions capable of being transferred to solution and destructuring iron oxides.     

Nanobiocomposites of noble metals based on arabinogalactan: Preparation and properties

A simple general method employing arabinogalactan hemicellulose as a reducing and stabilizing agent is used to synthesize hydrophilic nanoparticles of noble metals. The prepared organic-inorganic nanobiocomposites are characterized by electronic spectroscopy, powder X-ray diffraction, and scanning electron microscopy. The sizes of coherent scattering regions of the metal phase of the prepared nanocomposites are determined, and their surface morphology and grain size are demonstrated to be controlled by the nature of the nanosized metal.     

Improved Protocol for Mononitration of Phenols with Bismuth(III) and Iron(III) Nitrates

A simple and efficient multigram procedure was developed for the selective mononitration of various activated phenols. The reaction proceeded smoothly with 0.5 equivalents of Bi(NO₃)₃ · 5H₂O or Fe(NO₃)₃ · 9H₂O in acetone at ambient temperature or at reflux. The desired products were isolated in 62–93% total yield and essentially no overnitrated compounds were detected.     

Thiophosphorylation of Pharmacophoric Phenols,Diols, and Triols

Abstract

Novel organyldithiophosphonic and bis(aryldithiophosphonic) acids were obtained by the reaction of 2,4-diorganyl 1,3,2,4-dithiadiphosphetane-2,4-disulfides with paracetamol, 4-(1H-pyrrol-1-yl)phenol, ethambutol dihydrochloride, vitamin B₆, and its acetonide derivatives.     

Model Studies of Doped Iron Oxides. Reduction process of magnetite doubly doped with calcium and magnesium

The paper presents results of research on the effect of the presence of calcium and magnesium in magnetite structure on its reducibility. These are model studies of the phase which mostly affects reducibility of superfluxed sinter. Examinations were carried out on samples melted and crystallized in a single crystal growing process. This revised version was published online in August 2006 with corrections to the Cover Date.     

在铜铁、铜钴复合氧化物上利用CO低温催化还原NO

Copper iron composite oxides (CuO/Fe2O3) and copper cobalt composite oxides (CuO/Co3O4) for the catalytic reduction of NO with CO at low temperature were prepared by co-precipitation. The catalytic activity and thermal stability of the catalysts were evaluated by a microreactor-GC system. The 100% conversion temperatures of NO are 80 oC for CuO/Fe2O3 and 90 oC for CuO/Co3O4. The catalysts possess high catalytic activity and favorable thermal stability for NO reduction with CO in a wide temperature range and long time range. A systematic study of the molar ratios of the reactants, the volume of NaOH, aging time, and calcination temperature/time was carried out to investigate the influence preparation conditions on the catalytic activity of the catalysts.