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

Halogen-Free Flame Retarded Poly(Lactic Acid)with an Isosorbide-Derived Polyphosphonate

Fabrication of flame retardants from renewable biomass has aroused extensive interest over the past decade.This work reported a synthesis of isosorbide-derived polyphosphonate(PICPP)as an anti-flammable agent for poly(lactic acid)(PLA).The presence of PICPP notably declined the storage modulus of PLA/PICPP owing to the declined molecular weight of PLA catalyzed by the presence of PICPP.PLA and PLA/PICPP thermally degraded in one stage under either air or nitrogen atmosphere.With increasing the amount of PICPP,the onset thermal decomposition temperature of PLA/PICPP was decreased gradually,owing to the earlier decomposition of PICPP.With only 10 wt%of PICPP,PLA/PICPP-10 achieved a high limiting oxygen index of 30.0%and UL-94 V-0 classification,manifesting that PICPP was an efficient anti-flammable agent for PLA.The inclusion of 15 wt%PICPP also caused 33%and 16%decline in PHRR and THR of PLA,respectively.TG-IR results clarified that PLA/PICPP produced the less typical pyrolysis products especially flammable carbonyls than PLA,which may account for the suppressed PHRR and THR values of PLA/PICPP.

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

Nickel(Ⅱ)-Catalyzed Reductive Coupling of Xanthate Esters with Sulfur-Containing and Selenium-Containing Compounds:Synthesis of Unsymmetric Sulfides and Selenides

Unsymmetric sulfides and selenides have great applications in the pharmaceutical field.Herein,we describe the reductive coupling reaction of xanthate esters with sulfur-containing and selenium-containing compounds(thio(seleno)sulfonates and disulfides(selenides))under the nickel-catalyzed condition.It provides a mild and effective method for the synthesis of unsymmetric sulfides and selenides which has the advantages of mild reaction conditions,high yields and a wide range of substrates.

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.

阻燃剂PDPTP在PET中的阻燃机理研究

主要对一种含硫聚膦酸盐———聚硫代苯基膦酸(9,10-二氢-9-氧杂-10-膦酰杂菲)苯撑酯(PDPTP)在PET中的阻燃机理进行了研究。采用裂解色谱-质谱分析(PY-GC-MS)、热重-红外分析和X射线光电子能谱(XPS)等方法对聚对苯二甲酸乙二醇酯(PET)/PDPTP复合材料的热解产物进行分析。结果表明,PDPTP的存在有利于炭层的形成,延迟了炭层的分解;PDPTP中的硫元素在较低温度下会以SOx的形式挥发到气相中,对其中的小分子可燃物产生稀释而阻燃;而磷元素则在阻燃PET的第二分解阶段才会挥发,产生的含磷小分子物质可捕获火焰中的H.等自由基而中断燃烧过程中的链反应。PY-GC-MS分析表明,PDPTP可抑制PET的深度裂解反应,减少裂解中小分子可燃物的产生。XPS分析表明,PDPTP中磷元素在PET开始分解后会在表面炭层形成富集,并以磷酸和偏磷酸的形式存在。由于磷酸和偏磷酸是较强的脱水剂,可促进聚合物直接脱水成炭,避免了热解过程中小分子可燃物的产生,同时促进焦炭层的形成。

聚磷酸铵及其酯化的生产工艺

以磷酸和尿素为原料,制备聚磷酸铵无机阻燃剂。考察磷酸、尿素、反应温度和固化温度对聚磷酸铵平均聚合度的影响,用红外光谱分析法表征聚磷酸铵的晶体结构。以聚磷酸铵和季戊四醇为主要原料,合成具有一定含氮量的聚磷酸酯并采用红外光谱分析。

聚苯基膦酸二苯芴酯的合成与应用

以双酚芴和苯基膦酰二氯为原料,采用溶液聚合法合成了聚苯基膦酸二苯芴酯(PFPPP)。采用FTIR、1H-NMR和31P-NMR对PFPPP的结构、组成进行了表征,GPC和TGA分别对PFPPP的相对分子量、热稳定性能进行了表征,结果表明:成功合成了聚苯基膦酸二苯芴酯,其数均分子量可达11万,分子量分布为1.26,分布较窄;聚苯基膦酸二苯芴酯的初始分解温度为286℃,分解温度分布较宽,于845℃时PFPPP的成炭率高达45%。此外,对PFPPP在PC、PC/ABS体系的阻燃性能进行了测试,研究发现PFPPP在PC体系中的添加量(ω)为3%、PC/ABS体系中ω为5%时,两者阻燃级别均达到V-0级;当ω为10%时,PC的氧指数由25%提高到31%,可见PFPPP的添加提高了PC、PC/ABS的阻燃性能。

聚膦酸酯的合成与应用研究进展

介绍了聚膦酸酯的常用合成方法,包括溶液法、熔融法、界面缩聚法和相转移催化法;综述了聚膦酸酯在聚合物阻燃、生物医药和金属防腐等方面的应用研究进展;并展望了聚膦酸酯在相关领域的未来发展趋势。

聚甲基亚膦酸双酚A酯阻燃剂的合成及其应用

以甲基二氯膦和双酚A为单体,通过熔融缩聚合成了聚甲基亚膦酸双酚A酯(PMPBE)。通过傅里叶变换红外光谱(FTIR)、核磁共振谱仪、热失重分析仪(TGA)、差示扫描量热仪(DSC)、垂直燃烧仪、极限氧指数仪及微型量热仪表征了PMPBE及环氧树脂(EP)/PMPBE共混物的结构和性能。结果表明,随着PMPBE添加量的增加,复合材料的极限氧指数逐渐提高,最大放热速率和放热量逐渐降低,EP在700℃的残炭率明显提高。当添加20份PMPBE时,EP的极限氧指数从19.0%提高到27.6%,达到V-0级,最大放热速率与放热量均下降了27%;说明该阻燃剂是良好的本征型阻燃剂。

Sulfur-containing amino acid methionine as the precursor of volatile organic sulfur compounds in algea-induced black bloom

After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds （VOSCs）： methanethiol （MESH）, dimethyl sulfide （DMS）, dime^yl disulfide （DMDS）, dimethyl trisulfide （DMTS） and dimethyl tetrasulfide （DMTeS）. Even in the untreated control without a methionine addition, methionine and its catabolites （VOSCs, mainly DMDS） were found in considerable amounts that were high enough to account for the water＇s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine＋glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.

Sulfur-containing compounds as electrolyte additives for lithium-ion batteries

Originating from“rocking-chair concept”,lithium-ion batteries(LIBs)have become one of the most important electrochemical energy storage technolo-gies,which have largely impacted our daily life.The utilization of electrolyte additives in small quantities(≤5%by wt or vol)has been long viewed as an economical and efficient approach to regulate the properties of electrolyte and electrode–electrolyte interphases and consequently improve the cycling perfor-mance of LIBs.Among all the kinds of electrolyte additives,sulfur-containing compounds have gained significant attention due to their unique features in building stable electrode–electrolyte interphases and protect battery cells from overcharging.In this work,advances and progresses of sulfur-containing addi-tives used in LIBs are overviewed,with special attention paid to the working mechanisms of these electrolyte additives.Particularly,four representative sulfur-containing compounds(i.e.,1,3-propane sultone,prop-1-ene-1,3-sultone,1,3,2-dioxathiolane-2,2-dioxide,and ethylene sulfite)are comparatively dis-cussed concerning their impact on electrode–electrolyte interphases and cell per-formances.Future work on the development of sulfur-containing compounds as functional electrolyte additives is also provided.The present review is antici-pated to be not only a base document to access the status quo in this research domain but also a guideline to select specialized additives and electrolytes for practical applications.

Determination of sulfur anions by ion chromatography-postcolumn derivation and UV detection

A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed. All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0 mL/min. The postcolunm derivation solution was 0.24% iodine in 0.2% phosphate acid and the detection wavelength was set at 288 nm. The detection limits （LOD, signal-to-noise ratio of 3） of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate were 0.004, 0.006, 0.006, and 0.007 mg/L, respectively. Within-day relative standard deviations （RSD, n = 10） of formaldehyde sulfoxylate, sulflte, thiocyanate, and thiosulfate were 3.24%, 3.76%, 2.68%, and 2.07%, respectively. The recoveries of the four anions were in the range of 67.2-116.5%.