Determination of acid volatile sulphur in river sediments by ICP-OES coupled with purge and trap method

The developed and tested method is based on the acid volatile sulphur (AVS) releasing from a sample of sediment by acidification with hydrochloric acid and sequential absorption of released hydrogen sulphide into the absorption solution of sodium hydroxide. Total sulphur absorbed in the absorption solution is subsequently determined by inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The method was tested using both model and real samples of the river sediment. Obtained results were compared with the results of iodometric determination as the method routinely used for the AVS determination. In case of using ICP-OES with purge and trap, there is no spectral interference of calcium; therefore for the determination of sulphur, it is possible to use atomic emission line of sulphur S I 180.7 nm. The tested method provides the results comparable with the iodometric method within the range of tested concentrations. The detection limit (LOD) of this method is 0.09 mg· S^2? ? L^?1 in the absorption solution which corresponds to 0.23 mg S^2?·kg^?1 in a sediment. Value of LOD is comparable with the iodometric determination.     

低阶煤程序升温热解过程中钠、硅和硫间的相互作用

对一种澳大利亚低阶煤中,钠、硅和硫在热解过程中的相互作用进行了研究,以便深入了解钠的固硫作用和硫对流化床燃烧和气化中颗粒团聚的影响。制备了水洗、酸洗煤样和酸洗、乙酸钠离子交换煤样,样品在马弗炉中以17．7℃／min升至1000℃进行程序升温热解。对700℃-100℃热解半焦样品的依次水洗、酸洗、SEM—EDX和X射线元素扫描分析表明,部分有机结合的钠形成水溶性Na2O和NaOH化合物,水溶性的硅酸钠,以及与半焦中的硫形成酸不溶组分。最后一点解释了为何以往研究中发现,热解过程中有机结合的钠具有固硫作用,以及固硫历程中为何未发现Na2S的生成。在硅酸钠区域边缘存在的高硫区域,在流化床燃烧和气化过程中将形成含硫黏性相,导致床料的黏结。当用于酸洗、钠离子交换煤样的乙酸钠从0．25mol／L增加到1．0mol／L,固硫率将增加10％。相应的酸不溶钠组分的增加表明,酸不溶钠／硫组分随乙酸钠浓度的增加而增加,从而导致固硫率上升。     

Determination of sulfide with chloranilic acid by biamperometric and automatic potentiometric end-point detection with a lead chloranilate selective electrode

A titrimetric method for determination of sulfide and of sulphur in steels with chloranilic acid by biamperometric and automatic potentiometric end-point detection is described. The construction of the sensor for potentiometric indication is also described. The results obtained agree with those of the iodine-thiosulfate method and with the certified values for the steels.     

Studies of the soluble part of oxidised coals

Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO₃ contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.     

Study of oxidative desulphurization process of coal with different metamorphism degrees

The oxidative desulphurization process of coal with different metamorphism degrees treated by an air-steam mixture has been studied.It has been shown that the pyrite present in black coal and anthracite is oxidized with the sulphur dioxide formation,and the process chemical mechanism does not depend on the quality of organic matter.The medium-metamorphized coal,capable of turning into a plastic state and cake in the range of investigated temperatures(350～450 ℃),is desulphurized with the greatest difficulty.The chemical mechanism dealing with the transformations of pyritic sulphur present in brown coal differs from similar processes taking place in black coal and anthracite,because FeS2 is converted with hydrogen sulphide formation at desulphurization.     

Surface activity and fluorite flotation with myristic acid derivatives containing oxygen and sulphur atoms

Surface tension isotherms and fluorite flotation were studied in systems containing myristic acid derivatives in which carbon atoms in the hydrocarbon skeleton were partly replaced by oxygen and/or sulphur atoms. The location of the oxygen and sulphur atoms affects significantly compound hydrophobicity, adsorption at the air/water interface and fluorite flotation. The most effective collectors were the compounds with one oxygen or sulphur atom close to the carboxylic group.     

煤中有机硫的电化学脱除研究

煤的电化学脱硫是70年代末Coughglin和Fa rooque开发的一种温和脱硫方法,它不但克服了传统的高温、高压的脱硫缺点,而且可以联产氢气,从而大大降低了生产成本[1,2]。虽然近年来国内外对煤的电化学脱硫研究有些报道[3～6],但是脱硫效果都不理想,全硫脱硫率都在50%左右。作者在煤的电化学脱硫研究中发现有机硫的脱除较无机硫困难[7]。目前国内关于煤中有机硫的电化学脱除程度及影响规律的研究未见报道。为此,本文以川南贫瘦煤为原料,采用化学法脱除其中的无机硫后作实验煤样,研究了酸性体系中有机硫的脱除规律。1　试验部分1 1　原料与试…     

Study of sulphur in oxidised coals by atmospheric pressure-temperature programmed reduction

The influence of oxidation of coal, performed with different oxidising agents, on the sulphur species was studied. Conversions of the sulphur species were investigated by the Atmospheric Pressure-Temperature Programmed Reduction method (AP-TPR). The removal of pyrite proved to be advantageous for AP-TPR analysis. It was found that non-thiophene sulphur species undergo easier oxidation by different agent then thiophenic structures.This revised version was published online in November 2005 with corrections to the Cover Date.     

A practical method for the determination of sulphur in coal samples by high-resolution continuum source flame atomic absorption spectrometry

Sulphur in coal was determined using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS) with actylene/air flame. The C-S absorption band at 258.056 nm was found the most suitable analytical line with respect to sensitivity and spectral interferences. The instrumental parameters were optimized. The coal samples were dried and dissolved using microwave-assisted digestion technique. The validity of the method was tested using standard reference material and certified values were found in the limits of 95% confidence level. Since the concentrations of matrix elements of coal other than carbon are low enough not to cause any spectral interferences, the linear calibration method was applied in all quantifications without any problem. The calibration standards were prepared in sulphuric acid. The method was accurate, fast, simple and sensitive. The limit of detection (LOD, 3δ, N = 10) and the limit of quantification (LOQ, 10δ, N = 10) were found to be 0.01 and 0.03% (w/w), respectively. The sulphur concentrations of various kinds of the coal samples received around Turkey were determined. The sulphur contents of the coal samples were ranged from ≤LOQ to 1.2%.     

用XPS研究我国一些煤中有机硫的存在形态

本文用电子能谱（xps）方法研究了我国九个不同牌号煤中有机硫的存在形态，并得到这些煤中各种不同形态硫的结合能数据。根据Lindberg等人所做模型化合物结果，给出了这些煤中硫元素结构能的化学归属。各种煤中硫的存在形态是不同的，有硫醇、硫醚、双硫醚、硫杂环、硫桥和取代基上的硫等。这一研究结果为今后研究煤的分子结构及脱硫方法提供了重要的科学依据。     

Determination of sulphur and total sulphur dioxide in wines by an ICP-AES method

Sulphur contents of the original sample and the sample free from sulphur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulphur content was calculated from the difference between the results obtained. With the aim of preparing a sample free from sulphur dioxide, bound sulphur dioxide was released by sodium hydroxide, then after acidifying by phosphoric acid, boiling was carried out. Relative standard deviations of the results obtained for total sulphur, the sulphur without S(IV) and total sulphur dioxide were lower than 2.5, 3.5 and 5% respectively. Various amounts of sulphur (in the form of Na₂SO₄), added to wine samples, were successfully recovered between 95.5 and 104.9%. Based on comparative analyses performed by a widely accepted classic method, the indirect method developed was found to be adequate for the determination of total sulphur dioxide. The procedure is suitable for serial tests.     

型煤中硫的还原热解MS和GC/MS分析(英文)

以煤和生物质为主要原料的商用型煤为研究对象，采用还原热解（AP-TPR）在线质谱（MS）联用，以及离线色谱/质谱（GC/MS）分析法，定性和定量研究了家用型煤释放的含硫化合物。不同组成的型煤表现出各自不同的硫释放特性。对于生物型煤来说，仅检测到少量二烷基硫醚和脂肪硫醇的存在。褐煤型煤检测到种类最多的有机硫化物。在高阶煤制成的型煤中没有检测到氧化态的硫化物，其典型特征是存在一些噻吩类硫化物。     

焦煤中添加废塑料和脱硫剂的焦化过程研究

在模拟焦化室和焦化条件下，进行了焦煤中直接添加废塑料和脱硫剂后的焦化过程的研究，分析了焦化过程中焦炉煤气H2S脱除效果及脱硫剂和废塑料的添加对焦炭硫和锌及其在焦炭中残留率的影响。结果表明，焦煤的焦化过程中，直接添加ZnO、Fe2O3或冶金粉尘(MD)作为脱硫剂，当关键脱硫组分ZnO和（或）Fe2O3与可挥发性硫的摩尔比(nZn+Fe/nS)为1.2时，焦炉煤气H2S脱除效果均较好，塑料本身的热分解使得焦煤中添加质量分数为5%的废塑料后焦炭产率从81.52％降到77.61％；当焦煤中添加质量分数为5％的废塑料，并以ZnO为脱硫剂时，由于塑料中硫的质量分数相对焦煤要高，所以需要增nZn+Fe/nS到1.7，才能取得较好的煤气脱硫效果，与此同时焦炭中锌和硫的质量分数均有不同程度的增加。     

The effect of flame coal oxidation on the solid and soluble products of its extraction

Solid and soluble products of THF and CH₂Cl₂ extraction of flame coal oxidised by four different oxidising agents (peroxyacetic acid (PAA), 5% HNO₃, O₂/Na₂CO₃, air/125 °C) were studied by elemental analysis and FTIR. The extraction yield with THF was much higher than that with CH₂Cl₂ for all samples. The greatest changes in elemental composition were in the extracts from coal oxidised by nitric acid. The sulphur content was lowest in extracts from coal oxidised with 5% HNO₃ and PAA. FTIR confirmed that coal treatment with nitric acid incorporates nitrogen into the coal structure.     

Radiometric determination of sulphur content of coal

A new method of sulphur content determinations in hard coal is presented. The method is based on the measurements of backscatterd X-rays and -particles. The method is suitable for analysis of Polish coal of various chemical composition, finely pulverized and of grain size 0–30 mm.     

Coulometric argentometric determination of microamounts of sulphur in iron and steel after reduction to hydrogen sulphide with iron(II) in strong phosphoric acid medium

A coulometric method was developed for the determination of microamounts of sulphur in iron and steel. Hydrogen sulphide is quantitatively evolved by reduction with iron(II) in strong phosphoric acid medium and is titrated with electrolytically generated silver ion from a silver anode. Microamounts of sulphide (2.96–224.3 μg) in sodium sulphide standard solutions could be determined with an error of only a few percent. Sulphur in a potassium sulphate standard solution is quantitatively reduced to hydrogen sulphide and could be separated from the solution by heating and determined accurately. Trace amounts of sulphur (7–100 μg g^?1) in iron and steels could be determined with a standard deviation of 0.7–2.1 μg g^?1.     

Thermal analysis of fluidised bed combustion residues containing limestone scavenger

A method has been developed using thermoanalytical techniques for the analysis of residues from coal-burning fluidised bed plant where limestone is used as a sulphur scavenger. This completely eliminates the need for lengthy wet chemical analyses and allows the derivation of parameters necessary for efficient plant operation, such as limestone addition rate, calcium utilisation efficiency and calcium to sulphur mole ratio. The method also gives values for the unburned carbon content and the ratio of coal ash to limestone derivatives in the sample.     

Determination of trace amounts of sulphur in selenium

Determination of trace amounts of sulphur as Methylene Blue after reduction of sulphate to sulphide by hydriodic and hypophosphorous acids in acetic acid solution is applied to the determination of trace amounts of sulphur in selenium after removal of the selenium by evaporation with hydrobromic acid. Samples of 100 mg or less of selenium are chosen if the sulphur content is greater than 5-10 ppm; the time required for the separation is about 1.5 hr; 100 ppm of sulphur has been determined with a coeffident of variation of 5.2%. If the sulphur content is less than 5 ppm, 1-g samples must be taken and the time required is then about 3 hr; 0.4 ppm of sulphur has been determined with a standard deviation of 0.13 ppm. The accuracy of the method seems to be well within the random error.     

The fluorimetric determination of phosphate with thiamine

A method for the microdetermination of sulphur in organic compounds by means of combustion in a flow of oxygen is described. The oxides of sulphur are absorbed and stored on a small silver layer. After completion of the combustion, the oxygen is replaced first by nitrogen and secondly by hydrogen which liberates the sulphur as sulphur dioxide and regenerates the silver layer. The sulphur dioxide can be easily absorbed by dilute hydrogen peroxide and determined by any convenient method.     

Electrochemical method for sulphur dioxide removal from flue gases: Application on sulphuric acid plant in Tunisia

This article presents an electrochemical method for sulphur dioxide removal; the idea consists to couple the phenomenon of electrolysis upstream to the sulphuric acid plant. Otherwise, this proposition consists in modifying the hybrid cycle Westinghouse by the elimination of the sulphuric acid decomposition stage, which corresponds to 61% of the energy distribution of this cycle. The step of the decomposition is replaced by the exploitation of the quantity of sulphur dioxide emissions SO₂ stemming from the process of sulphuric acid H₂SO₄ production. The industrial complex of Gabès in South Tunisia is selected to be the case study complex. In fact, most industries are chemical oriented, the fast growing numbers of H₂SO₄ factories have resulted in fairly serious air pollution, especially sulphur dioxide SO₂ pollution. To confirm the efficiency of this process, a mass balance study was made on the sulphuric acid plant, which used a double contact/double absorption process; this study demonstrates that this new method can treat 8 t d^?1 of sulphur dioxide, recover 12 t d^?1 of sulphuric acid of title 50% and produce 6889 m³ d^?1 of the hydrogen. This idea can achieve economical and environmental benefits. It is concluded that the usage of this electrochemical process can significantly reduce the SO₂ air pollution in Gabès (South Tunisia) by the elimination of 46.94 t d^?1 of SO₂. The results obtained are ambitious for future application of the new process, which can succeed in the realisation of 3.92 million dollars of gain every day.