The role of variable surface charge and surface complexation in the adsorption of humic acid on magnetite

The ionic strength dependence of humic acid (HA) adsorption on magnetite (Fe₃O₄) was investigated at pH 5, 8 and 9, where variable charged magnetite is positive, neutral and negative, respectively. The adsorption studies revealed that HA has high affinity to magnetite surface especially at lower pH, where interacting partners have opposite charges. However, in spite of electrostatic repulsion at pH 9 notable amounts of humate are adsorbed. Increasing ionic strength enhances HA adsorption at each pH due to charge screening. The dominant interaction is probably a ligand-exchange reaction, nevertheless the Coulombic contribution to the organic matter accumulation on oxide surface is also significant under acidic condition. The results from size exclusion chromatography demonstrate that the smaller size HA fractions enriched with functional groups are adsorbed preferentially on the surface of magnetite at pH 8 in dilute NaCl solution.     

Kinetic features of ethylene polymerization over supported catalysts [2,6‐bis(imino)pyridyl iron dichloride/magnesium dichloride] with AlR3 as an activator

The effects of polymerization temperature, polymerization time, ethylene and hydrogen concentration, and effect of comonomers (hexene‐1, propylene) on the activity of supported catalyst of composition LFeCl₂/MgCl₂‐Al(i‐Bu)₃ (L = 2,6‐bis[1‐(2,6‐dimethylphenylimino)ethyl] pyridyl) and polymer characteristics (molecular weight (MW), molecular‐weight distribution (MWD), molecular structure) have been studied. Effective activation energy of ethylene polymerization over LFeCl₂/MgCl₂‐Al(i‐Bu)₃ has a value typical of supported Ziegler–Natta catalysts (11.9 kcal/mol). The polymerization reaction is of the first order with respect to monomer at the ethylene concentration >0.2 mol/L. Addition of small amounts of hydrogen (9–17%) significantly increases the activity; however, further increase in hydrogen concentration decreases the activity. The IRS and DSC analysis of PE indicates that catalyst LFeCl₂/MgCl₂‐Al(i‐Bu)₃ has a very low copolymerizing ability toward propylene and hexene‐1. MW and MWD of PE produced over these catalysts depend on the polymerization time, ethylene and hexene‐1 concentration. The activation effect of hydrogen and other kinetic features of ethylene polymerization over supported catalysts based on the Fe (II) complexes are discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5057–5066, 2007     

深圳市1408例儿童发中钙,铁,镁含量调查与分析

用火焰原子吸收法检测了深圳市１４０８例１３岁以下儿童发中钙，铁，镁的元素含量，并探讨了元素含量与年龄，性别的关系，结果显示，性别差异有显著意义，钙，镁含量随年龄增长有相似变化。     

Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)₂Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC₆H₄)₃ and P(4-MeC₆H₄)₃. The products of the reaction, [CpFe(CO)(COMe)P(4-FC₆H₄)₃] (2a) and [CpFe(CO)(COMe)P(4-MeC₆H₄)₃] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) Å in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) Å in 2b, respectively.The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC₆H₄)₃ was observed when the solvent was changed from CH₂Cl₂ to MeCN. The kinetic data showed that P(4-MeC₆H₄)₃ reacts faster than P(4-FC₆H₄)₃.     

停留—催化反应速差动力学法同时测定Fe,Mo

根据Ｆｅ（Ⅲ）、Ｍｏ（Ⅵ）对Ｈ２Ｏ２氧化邻氨基酚的催化反应速率不同，结合流动注射停留技术，建立了同时测定Ｆｅ（Ⅲ）、Ｍｏ（Ⅵ）的速差动力学分光光度法．测定铁和钼的线性范围分别为０．１～２．５μｇ／ｍＬ和０．５～１５μｇ／ｍＬ．除Ｗ（Ⅵ）的允许量较小外，其它离子不干扰测定．用本法测定了合成样液中铁和钼含量，结果满意．     

Preparation of trout liver microsomes for iron speciation in P-450 enzymes by AE–FPLC with ICP–(ORS)MS detection

Cytochromes P-450 are members of a superfamily of hemoproteins involved in the oxidative metabolism of various physiological and xenobiotic compounds in eukaryotes and prokaryotes. The multiplicity of this group of enzymes has been widely studied by chromatographic techniques, mainly high-performance liquid chromatography (HPLC). Because these enzymes are membrane-bound proteins, sample preparation for chromatographic separation of P-450 enzymes requires a solubilization step. The sample-preparation procedures are critical, because detergents affect not only the efficiency of protein solubilization but also their further chromatographic resolution. Trout liver microsomes have been taken here as a model sample to investigate iron speciation in cytochrome P-450. Trouts were treated intraperitoneally with -naphthoflavone, a potent inducer of some P-450 enzymes, and a microsomal suspension containing 7.4±0.1 nmol mL^–1 P-450 enzymes was obtained by ultracentrifugation. Lubrol PX was selected as detergent for solubilization, resulting in about 90% solubilization recovery. The solubilized cytochromes P-450 were further separated by AE–FPLC, with UV detection, or coupled to ICP–MS with an octapole reaction system, ICP–(ORS)MS (monitoring Fe signals at masses 54, 56, and 57). A sampling procedure and chromatographic conditions are developed and were successfully applied to iron speciation in trout liver P-450 enzymes. ICP–(ORS)MS detection of P-450 enzymes is Fe-specific and so will give accurate information on the prosthetic group of the protein, which can constitute an advantageous alternative to classical methods for detection of these hemoproteins.     

Magnetic field effects on the crystal orientation and surface morphology of electrodeposited iron films

The effects of a magnetic field (5 T) on crystal orientation and surface morphology were investigated for iron films electrodeposited in ferrous aqueous solution. XRD measurements for the iron films showed that the preferred orientation parallel to the substrate was determined by the current density and not influenced by the magnetic field. By X-ray pole figure measurements, however, the crystal texture of the iron films electrodeposited at 10 mA cm^–2 and 30 mA cm^–2 was found to be controlled by the magnetic field. That is, the (110) planes were orientated in same direction of the magnetic field vector at angles of 30° and 35° to the direction normal to the substrate plane at 10 mA cm^–2 and 30 mA cm^–2, respectively. When the morphology was observed by SEM, iron grains at 30 mA cm^–2 changed from a triangular pyramid shape at 0 T to a complex star-like shape at 5 T.Presented at the 3rd International Symposium on Electrochemical Processing of Tailored Materials held at the 53rd Annual Meeting of the International Society of Electrochemistry, 15–20 September 2002, Düsseldorf, Germany     

Bis-chelate Fe(III) complex of an azomethine at the focal point of a branched ester functionalized with cyclohexylbenzoic acid

A Fe(III) complex with Cl counter ion based on a branched Schiff base has been synthesized and studied. The compound was produced by the reaction of the Schiff base with FeCl₃ at room temperature in benzene–ethanol. The complex is symmetric, i.e., bis-chelate, with an octahedral coordination of Fe. The compound revealed phase transitions of the “solid–solid” type. The complex displayed a temperature-induced spin transition (S?=?1/2???5/2) which was detected by EPR.     

Syntheses and molecular structures of four inorganic–organic hybrid compounds from N-containing aromatic bases and perchlorometallates of Zn,Cu, Sn,and Fe

Four organic–inorganic crystals, [(HL1)₂(ZnCl₄)]·H₂O (1) (L1?=?2-methylquinoline), [(HL1)₂(CuCl₄)] (2), [(HL2)₂SnCl₆] (3) (L2?=?6-bromobenzo[d]thiazol-2-amine), and [(HL3)FeCl₄] (4) (L3?=?5,7-dimethyl-1,8-naphthyridine-2-amine), derived from N-containing aromatic Brønsted bases and metal(II) chlorides (zinc(II) chloride, copper(II) chloride dihydrate, tin(II) chloride dihydrate, and iron(III) chloride hexahydrate) were prepared at room temperature and characterized by IR, X-ray structure analysis, elemental analysis, and TG analysis. The crystals are built up by perchlorometallates (Zn, Cu, Sn, and Fe) associated with organic cations through multiple non-covalent associations. X-ray diffraction analysis reveals that 1 and 2 have 3-D network structures built from hydrogen bonds between the cations and chlorometallates. Water molecules play an important role in structure extension in 1. Anhydrous 3 and 4 produced from 2-aminoheterocyclic derivatives display 2-D sheet structures. Arrangements of anions and cations are dominated by shape and size of cations, and also by the different structures of the chlorometallates as well as non-bonding interactions in the crystal structures. Except for 1, the other compounds are thermally stable below 240°C.