Sulfur phase and sulfur removal in high sulfur-containing bauxite

The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.

Highly Efficient and Selective Removal of Pb（II） ions by Sulfur-Containing Calcium Phosphate Nanoparticles

A facile one-step co-precipitation method was demonstrated to fabricate amorphous sulfurcontaining calcium phosphate （SCP） nanoparticles, in which the sulfur group was in-situ introduced into calcium phosphate. The resulting SCP exhibited a noticeable enhanced performance for Pb（II） removal in comparison with hydroxyapatite （HAP）, being capable of easily reducing 20 ppm of Pb（II） to below the acceptable standard for drinking water within less than 10 min. Remarkably, the saturated removal capacities of Pb（II） on SCP were as high as 1720.57 mg/g calculated by the Langmuir isotherm model, exceeding largely that of the previously reported absorbents. Significantly, SCP displayed highly selective removal ability toward Pb（II） ions in the presence of the competing metal ions （Ni（II）, Co（II）, Zn（II）, and Cd（II））. Further investigations indicated that such ultra-high removal efficiency and preferable affinity of Pb（II） ions on SCP may be reasonably ascribed to the formation of rodlike hydroxypyromorphite crystals on the surface of SCP via dissolution-precipitation and ion exchange reactions, accompanied by the presence of lead sulfide precipitates. High removal efficiency, fast removal kinetics and excellent selectivity toward Pb（II） made the obtained SCP material an ideal candidate for Pb（II） ions decontamination in practical application.

A review of gold extraction using noncyanide lixiviants: Fundamentals, advancements, and challenges toward alkaline sulfur-containing leaching agents

Alkaline sulfur-containing lixiviants,including thiosulfate,polysulfides,and alkaline sulfide solutions,stand out as a promising class of alternatives to cyanide because of their low toxicity,high efficiency,and strong adaptability.In this paper,we summarized the research progress and remaining challenges in gold extraction using these noncyanide reagents.After a brief introduction to the preparation method,the transformation process of various sulfur-containing species in alkaline solutions was discussed.Thereafter,some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were presented from different aspects,including thermodynamics analysis,electrochemical dissolution,and leaching kinetics.Moreover,recent progress in in-situ generation of sulfur-containing anions from gold-bearing sulfide minerals was outlined as well.Gold passivation caused by sulfur species was discussed in particular because it is considered the greatest challenge facing sulfur-containing leaching systems.Alkaline sulfur-containing lixiviants are expected to serve as alternatives in industrial applications of gold extraction,particularly for refractory gold ores containing copper and carbonaceous matter.

pH variation mechanism of high sulfur-containing bauxite

In order to fundamentally solve the acidification problem of high sulfur-containing bauxite during storage, by simulating the environment of minerals storage in laboratory, the acidification mechanism and influencing factors of high sulfur-containing bauxite were studied and confirmed using the single variable method to control the atmosphere, water and other variables. The results show that the acidification is mostly caused by the oxidation of sulfur-containing bauxite, which is mainly the natural oxidation of Pyrite(Fe S2), then the alkaline minerals dissolute in the presence of water, leading to the acidification phenomenon, which is influenced by moisture and air flow. Finally, more acid-producing substances are formed, resulting in the acidification of high sulfur-containing bauxite. The acidification of high sulfur-containing bauxite results from the combined effect of the oxygen in the air and water, which can be significantly alleviated by controlling the diffusion of the oxygen in air.

Synthesis and Characterization of New Schiff Bases Formed by Condensation of 2,9-Phenathroline-1,10-dialdehyde with Sulfur-Containing Amines

Four new Schiff bases of 1,10-phenanthroline-2,9-dicarboxaldehyde with sulfur-containing amines such as 2-mercaptoaniline, S-alkyl/aryl dithiocarbazates and thiosemicarbazide have been synthesized and characterized by spectroscopic and X-ray crystallographic techniques. A comparative study of the methods of synthesis has been made using both traditional and microwave techniques. A significant reduction in reaction time has been observed when the microwave method was used. In some of the reactions, the yields also increased significantly.

QSPR Study on the Boiling Points of Some Oxygenand Sulfur-containing Organic Compounds

Structural and thermodynamic parameters of 56 oxygen-containing and 56 sulfur- containing organic compounds were computed at the B3LPY/6-311G＊＊ level using density functional theory （DFT） method. Furthermore,the dependent equations between the experimental data of boiling points （Tb） and theoretical parameters were proposed with SPSS12.0 for windows software,whose correlation coefficients R2 are 0.933 and 0.945. These dependent equations were validated by cross-validation method （q2 are 0.923 and 0.929,respectively）. VIF （variance inflation factors） and t-value methods were also used to verify the significance and self-correlationship of each variable. Results indicate that our dependent equation exhibits good prediction ability,and molecular polarizability （α） is the main factor affecting the Tb of oxygen- and sulfur-containing organic compounds. To our interest,obvious dependence could also be found among the oxygen- and sulfur-containing organic compounds＇ experimental data of boiling points （Tb） with R^2 of 0.857.

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.

An Innovative Method for the Determination of Sulfur-containing Compounds by Vapor Molecular Absorption Spectrometry

Since the most sensitive resonance lines of nonmetallic elements are situated in vacuum ultraviolet region （below 190 nm）, they can not be directly determined with a common AAS instrument covering the spectral range from 190 to 700 nm. The molecular absorption spectrometry is often used for the determination of nonmetallic elements. Syty et al. used vapor molecular absorption spectrometry（VMAS） to determine the sulfur dioxide and sulfide, in which a hydrogen hollow cathode lamp was used as a continuum source to determine SO;at 210 nm and a deuterium arc

The Synthesis of New Sulfur-containing Chiral Macrocyclic Ligands

Five new chiral sulfur-containing macrocyclic ligands which can be used in chiral recognition to guests have been synthesized and characterized

Comparison of the capacity of biological desulfurization of Thiobacillus ferrooxidans from different sulfur-containing substrates with or without additional ferrous iron

Thiobacillus ferrooxidans,abbreviated as T.ferrooxidans is one of the important microorganisms in the field of biological desulfurization.Effects of ferrous iron and sulfur-containing substrates on biological desulfurization of T.ferrooxidans were studied.Results show that in the absence of Fe^(2+),T.ferrooxidans can utilize three kinds of sulfur-containing substrates of Na_(2)S_(2)O_(3),elemental S and Na_(2)SO_(3) for growth and metabolism.For utilization complexity,Na_(2)S_(2)O_(3) was easiest to use,next was elemental S,and Na_(2)SO_(3) was the worst for use.During the utilization of ferrous iron and sulfur-containing substrates by T.ferrooxidans,the iron oxidation system was first started.With the decrease of the Fe^(2+)concentration,the sulfur oxidation system was started,and then the two systems synergistically acted.The presence of three sulfur-containing substrates had different effects on Fe^(2+)oxidation,and elemental S did not inhibit the oxidation of Fe^(2+),while Na_(2)S_(2)O_(3) and Na_(2)SO_(3) had some inhibition on the oxidation of Fe^(2+),especially the inhibition of Na_(2)SO_(3) was significant,and complete oxidation of ferrous iron needed more time.The isolated T.ferrooxidans is applied to the removal of H2S gas,aiming to provide a new technological approach for biological removal of H2S.

(Et_4N)_2[Fe_4(SPh)_10] Stimulated S_(RN)1 Reactions of α-Bromonaphth-alene with Pinacolone Carbanion

The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.

Regioselechve Reaction of α－（Alkoxydimethylsilyl）allyl Carbanions with Alkyl Halides and Aldehydes

The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied. α-Alkylation with alkyl halides was favoured, whereas γ-selection was achieved in the reaction with aldehydes.

Selenium-doped cathode materials with polyaniline skeleton for lithium-organosulfur batteries

Sulfur-containing polymer(SCP)is considered as an outstanding cathode material for lithium-sulfur batteries.However,undesirable soluble polysulfides may shuttle in electrolyte,concluding long-chain Li_(2)S_(n)(n>4)and short-chain Li2Sn(n≤4),as well as the sluggish conversion kinetics are yet to be solved to enhance the performance of lithium-sulfur batteries.Here Se-doped sulfurized polyaniline with adjusted sulfur-chain-S_(x)-(x≤6)contribute to ensure the absence of long-chain polysulfides,and the skeleton with quinoid imine can endow strongly adsorption towards short-chain polysulfides by the reversible transition between deprotonated/protonated imine(-NH^(+)=and-N=),which offer double insurance against suppressing“shuttle effect”.Furthermore,Se atoms are doped into sulfurized polysulfides to accelerate the redox conversion and take a frontier orbital theory-oriented view into catalytic mechanism.Se-doped sulfurized polyaniline as active materials for lithium-organosulfur batteries delivers good electrochemical performance,including high rate,reversible specific capacity(680 mA h g^(-1)at 0.1 A g^(-1)),and lower capacity decay rate only of 0.15%with near 100%coulomb efficiency during long-term cycle.This work provides a valuable guiding ideology and promising solution for the chemistry-oriented structure design and practical application for lithium-organosulfur batteries.

氧气液相氧化法制备邻硝基苯甲醛

氧气直接液相氧化邻硝基甲苯一步合成邻硝基苯甲醛 ,成本低 ,污染少 ,腐蚀性小。反应以有机胺为溶剂 ,在 5℃ ,催化剂加入量 0 .0 5 g,反应时间 4 .5 h条件下 ,邻硝基甲苯转化率为 4 1% ,邻硝基苯甲醛得率为36 % ,同时对反应机理也作了初步探讨 。

海因酶转化体系中消旋过程研究

提出了5 单取代海因的消旋机理,考察了L 5 甲基海因的消旋反应动力学,建立了其动力学模型并进行了计算,得出L 5 甲基海因在不同条件下的半衰期以及消旋的最优条件;同时考察了海因消旋过程对转化的影响。

L-α氨基酸消旋化作用的探讨

Ｌ－α氨基酸消旋化作用的探讨方百盈冯大炎（安徽师范大学化学系，芜湖，２４１０００）关键词Ｌ－α－氨基酸消旋化负碳离子作为人体必需的８种氨基酸及２种半必需氨基酸往往易在食品加工过程中发生变化，并导致营养值下降［１］。虽原因有多种，但构型的转变，旋光度下...

有机膦螯合树脂研究Ⅰ．D301－CMP树脂的合成及其对Am、Cm的吸附性能

报道了Ｎ，Ｎ－二乙胺甲酰甲撑二己基磷酸酯（ＤＨＤＥＣＭＰ）螯合树脂的合成及其对Ａｍ、Ｃｍ吸附行为的研究。用红外光谱法对树脂进行了表征。ＤＨＤＥＣＭＰ在树脂上的加接率为０．２７。在低酸度时，该树脂与纯ＤＨＤＥＣＭＰ的萃取行为有较大差异，而与未纯化的ＤＨＤＥＣＭＰ比较接近，在高酸度下两者的萃取行为基本一致。

(2,6-二氯-5-氟-吡啶-3-羰基)-乙酸乙酯的合成

(2,6-二氯-5-氟-吡啶-3-羰基)-乙酸乙酯是合成沙星类药物和其他喹诺酮类抗菌药的关键中间体。以2,6-二氯-5-氟-吡啶-3-羧酸,二氯亚砜为原料发生亲核取代反应制得2,6-二氯-5-氟-吡啶-3-酰氯;以β二羰基化合物丙二酸二乙酯与乙醇镁反应生成强亲核试剂[C2H(COOC2H5)2]-碳负离子;它再与2,6-二氯-5-氟-吡啶-3-酰氯发生亲核取代反应制得(2,6-二氯-5-氟-吡啶-3-羰基)丙二酸乙酸乙酯;在对甲苯磺酸的作用下经过酯的水解和β-二酸的脱羧得目的产物(2,6-二氯-5-氟-吡啶-3-羰基)-乙酸乙酯。对反应条件进行了改进,选用了比较廉价的原料,并对重结晶试剂进行了深入的筛选,得到具有良好晶形的目的产物。

有机化学常见活性中间体详解

碳正离子、碳负离子作为最常见有机反应活性中间体,涉及反应类型众多,易出现中间体重排,一直是有机化学的重点和难点。文章从概念、结构、稳定性、生成和湮灭等五个方面对这两种有机活性中间体分别加以介绍,便于对比掌握这两类有机活性中间体的特性与反应。

2,2,2-三氟卤乙烷和碳负离子的自由基亲核取代反应

主要研究 2 ,2 ,2 -三氟卤乙烷 (碘、溴、氯、氟 )和碳负离子的反应 ,在一定的温度下 ,以 DMF作溶剂 ,除了 2 ,2 ,2 -三氟氟乙烷外 ,反应都得到了相应的 2 ,2 ,2 -三氟卤乙烷的衍生物以及碳负离子的偶联产物 .该反应能被紫外光加速 ,能被对二硝基苯和对二苯酚阻止 .因此 ,该反应是按 SRN1即自由基亲核取代反应机理进行 .由于此反应能在黑暗中进行 ,所以它可能是通过热引发或自发引发来完成的 .