Sulfur determination

Ln(II) in LnFj Ln(II) were determined after samples dissolution in H PO in the presence of a titrated solution of NFI VO, which excess was titrated with the Fe(II) salt. It was found that dissolution of the materials based on CeF CeFj in H PO does not change the oxidation state of cerium, thus phosphate complexes of Ce(III, IV) can be used for quantitative spectrophotometric determination of cerium valence forms. The contents of Ln(II, III) in Ln S LnS may be counted from results of the determination of total sulfur (determined gravimetric ally in BaSO form) and sum of the reducers - S and Ln(II) (determined by iodometric method). 

Additional data on sulfur determination by simple absorptiometry are... 

Iron, thickness measurement, 150-152 trace analysis by x-ray emission spectrography, 163, 225-232 Iron-55, as x-ray source for sulfur determination, 130, 133-135 Iron oxides, analysis, 182, 184 Irradiance, definition, 6 Irradiation, equipment for, 177 of polymers, 177... 

Obtaining accurate results for sulfur determination at ppm level is illustrative of a problematic element. Trace sulfur analysis is an analytical challenge. Sulfur cannot be determined by conventional AAS, since its... 

Micro amounts of sulfur in polymer are usually determined by oxygen flask combustion, sodium peroxide fusion in a metal bomb followed by titration [30], pyroluminescence [36] or ICP-AES. An oxygen flask combustion photometric titration procedure capable of determining total sulfur in polymers in amounts down to 50 ppm was reported. The repeatability of the sulfur determination in polyolefins in the oxygen flask is 40% at 50 ppm level, improving to 2% at the 1 % level [21]. Crompton [31] has also combined Schoniger flask combustion with a colorimetric procedure for the determination of phosphorous in polymers in various concentration ranges (0.01 to 2%, 2 to 13%). 

In all treated fruit the percentage of sulfur determined as sulfate in peel increased over the controls (Table IV). Of the four different treatments, the sulfate having the highest percentage specific activity was where elemental sulfur was applied. Specific activity was next highest in the hydrogen sulfide and lowest for the sulfur dioxide treatment. 

Rasmussen [82] describes a gas chromatographic analysis and a method for data interpretation that he has successfully used to identify crude oil and bunker fuel spills. Samples were analysed using a Dexsil-300 support coated open tube (SCOT) column and a flame ionisation detector. The high-resolution chromatogram was mathematically treated to give GC patterns that were a characteristic of the oil and were relatively unaffected by moderate weathering. He compiled the GC patterns of 20 crude oils. Rasmussen [82] uses metal and sulfur determinations and infrared spectroscopy to complement the capillary gas chromatographic technique. 

Total and soil organic carbon, and total sulfur determinations of soils... 

Kola H, Peramaki P, Valimaki I. Correction of spectral interferences of calcium in sulfur determination by inductively coupled plasma optical emission spectroscopy using multiple hnear regression. J. Anal. At. Spectrom. 2002 17 104-108. 

As for the nature of the ionic intermediates, it is noteworthy that, independently of their representation, the bridged ions are not necessarily symmetrical species. The substituents at the ring carbons as well as at sulfur determine the amount of positive charge... 

Optically Active Sulfur Compounds Absolute Configuration at Sulfur Determined by X-Ray Analysis... 

Analytical methods are available in standard form for determining volatile sulfur content and certain specific corrosive sulfur compounds that are likely to be present. Volatile sulfur determination is made by a combustion procedure... 

The bomb method for sulfur determination (ASTM D129) uses sample combustion in oxygen and conversion of the sulfur to barium sulfate, which is determined by mass. This method is suitable for samples containing 0.1 to 5.0% w/w sulfur and can be used for most low-volatility petroleum products. Elements that produce residues insoluble in hydrochloric acid interfere with this method this includes aluminum, calcium, iron, lead, and silicon, plus minerals such as asbestos, mica, and silica, and an alternative method (ASTM D1552) is preferred. This method describes three procedures the sample is first pyrolyzed in either an induction furnace or a resistance furnace the sulfur is then converted to sulfur dioxide, and the sulfur dioxide is either titrated with potassium iodate-starch reagent or is analyzed by infrared spectroscopy. This method is generally suitable for samples containing from 0.06 to 8.0% w/w sulfur that distill at temperatures above 177°C (351°F). 

The mercaptan-sulfur determination may be waived at the option of the Inspector, if the fuel is considered Doctor sweet when tested in accordance with Method 5203 of Federal Test Method Standard No 791... 

Glenn C. Soth. Was manganese distribution studied I have encountered an Oklahoma coal (medium volatile) with manganese high enough to interfere with the usual Eschka sulfur determination. 

These coke samples were studied by chemical, x-ray diffraction, and microscopic techniques. Chemical data include total carbon, volatile matter, ash, and sulfur determinations. 

Sulfur is an important consideration in coal utilization, and hence, there is a considerable amount of published work relating to the development of methods to improve the efficiency of the techniques as well as improve the accuracy and precision of the sulfur determination (Ahmed and Whalley, 1978 Chakrabarti, 1978a Attar, 1979 Raymond, 1982 Gorbaty et al 1992). 

The three most widely used test methods for sulfur determination are (1) the Eschka method, (2) the bomb washing method, and (3) the high-temperature combustion method, and all are based on the combustion of the sulfur-containing material to produce sulfate, which can be measured either gravimetrically or vol-umetrically. The Eschka method has distinct advantages in that the equipment... 

A LECO sulfur determinator (Model 532) was used for analysis of sulfur in the products. 

A procedure for the direct determination of the sulfate, sulfide, pyritic, and organic sulfur in a single sample of coal has been reported by McGowan and Markuszewski (17). The method uses various strengths of perchloric acid as the selective oxidizing agent. The results obtained for the analysis of three coals were comparable to ASTM results and the relative standard deviations for nine sulfate, four pyritic, six organic, and four total recovered sulfur determinations were 2.7, 3.4, 2.4, and 2.4%, respectively. 

Analytical Procedures. The samples of bituminous coals were analyzed for pyritic sulfur, sulfate sulfur and total sulfur using conventional wet chemical procedures adapted from the American Society of Testing Materials (23, 24). The ASTM D 3177-75, The Eschka method was used for the total sulfur, and ASTM D-2492-79was used for sulfate and pyritic sulfur determinations. The treated samples were filtered through a Whatman 2 filter paper to separate the coal particles from the liquid medium. The filtered sample was washed with 0.1 N HCl followed by distilled water to remove traces of absorbed sulfate and iron. 

Another slurry pipeline desulfurization experiment was conducted using Indiana 3 (Ayrshire) coal as a 25 wt% slurry in deionized water. The other process variables were carefully controlled flow rates 6-6.5 ft/sec, temperature 70-90°F, and pH 2.5 -2 8.The experiment was continued for 14 days, and the slurry samples for pyritic sulfur determination were taken daily. The desulfurization rates with Indiana 3 coal in the pipeline experiment are shown in Table 4 and are in good agreement with the laboratory data and the results with Illinois 6 coal. As observed in the laboratory experiments, the rate of desulfurization of bituminous coals is directly proportional to the pyritic sulfur content and inversely to the particle size of the coal sample. 

The surface saturation by sulfur has to be compared to the irreversible adsorbed sulfur introduced by Menon and Prasad (22) and Apesteg-uia et al. (23). The study of H2S adsorption on supported catalysts was carried out by Menon and Prasad (22) and Apesteguia et al., Parera et al., and Barbier et al. and Marecot (23-25). For alumina supports, it was shown (23-25) that chlorine inhibits the adsorption of H2S on the support. Yet this adsorption on pure alumina is wholly reversible at 500°C, as is shown in Fig. 2. On Pt/Al203 at 500°C, only a fraction of the adsorbed sulfur is quickly desorbed in a hydrogen atmosphere. This result enabled the preceding authors (22-25) to develop the notion of reversible and irreversible adsorbed sulfur. The irreversible form, which does not exist on pure alumina, would interact with the metal. The quantity of irreversible sulfur, determined after 30 h of desorption under hydrogen flow at 500°C, does not depend on the sulfiding conditions (Table I). 

Irreversible sulfur determined after a 30-h desorption under H, at 773 K. 

The total sulfur (determined as sulfate) in the filtrates from the acid extractions was converted to per cent sulfur in the original dry coal by ... 

Sulfur Determine as directed under Sulfur, Appendix me. 

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