Determination of total sulfur content

The determination of total sulfur content is applied to both natural aggregates and air-cooled blast-furnace slags and is carried out according to CEN EN 1744-1 (2009), paragraph 11. 

A representative test portion of aggregates (about 1 g, passing through the 0.125 mm sieve) is treated with bromine and nitric acid to convert any sulfur compounds into sulfates. Sulfates in the form of BaS04 sink and then weighed. The total sulfur content is expressed as a percentage by mass of aggregate. 

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Determination of the level of total sulfur in a rubber can give information on the type of cure system used, for example, elemental sulfur plus accelerator or sulfur donor system, etc. The ISO 6528-1 1992 method — Rubber — Determination of total sulfur content — Part 1 Oxygen combustion flask method is often employed. The principle of the method is oxidation by ignition in an atmosphere of oxygen in the presence of hydrogen peroxide, conversion of sulfur to sulfuric acid and determination of the sulfate by titration with barium perchlorate. The method is... 

Ultimate analysis of coal and coke, determination of total sulfur content, Eschka method Ultimate analysis of coal and coke, determination of total sulfur content, high temperature combustion method... 

Until recently, one of the most widely used methods for determination of total sulfur content has been combustion of a sample in oxygen to convert the sulfur to sulfur dioxide, which is collected and subsequently titrated iodometricaUy or detected by nondispersive infrared (ASTM D-1552). This method is particularly applicable to heavier oil and fractions such as residua that boil above 177°C (350°F) and contain more than 0.06% w/w sulfur. In addition, the sulfur content of petroleum coke containing up to 8% w/w sulfur can be determined. 

The total sulfur content of gasoline is very low, and knowledge of its magnitude is of chief interest to the refiner who must produce a product that conforms to a stringent specification. Various methods are available for the determination of total sulfur content. The one most frequently quoted in specifications is the lamp method (ASTM D-1266, IP 107), in which the gasoline is burned in a small wick-fed lamp in an artificial atmosphere of carbon dioxide and oxygen the oxides of sulfur are converted to sulfuric acid, which is then determined either volumetricaUy or gravimetrically. 

Until recently, one of the most widely used methods for determination of total sulfur content has been combustion of... 

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). 

Micrographic examination verifies that the addition of 10% sulfur to asphalt produces a monophasic product. The physical methods for determining these solubilities have been completed by chemical determinations of the sulfur content in each phase total sulfur dispersed and sulfur content of each part of the bituminous phase (maltenes, asphal-... 

Sulfur occurs in both organic and inorganic combinations. For certain purposes a knowledge of total sulfur content is adequate however, for coal preparation and conversion processes, determination of the forms of sulfur (organic, pyritic, and sulfate) is valuable. 

Total SulfuT Dioxide After Alkali Treatment The fact that neutral sodium sulfite does not combine with carbonyl compounds and that the hydroxysulfonic acid compounds are rapidly decomposed on treatment with alkali was used by Ripper (1892) as the basis for the determination of total sulfur dioxide in wine by direct iodine titration. In his method, 50 ml. of wine were pipetted into a 200-ml. flask containing 25 ml. of 1 iV KOH. The mixture was shaken and allowed to stand for 10 to 15 minutes. Then 10 ml. of dilute sulfuric acid (1 + 3) were added, and the solution titrated rapidly with 0.02 N iodine solution to a starch end point which persisted for some time. This method was used as the ofiicial direct titration method for wine in the first edition (1919) of the A.O.A.C. Methods of Analysis in the third (1930) edition it was extended to white grape juice, wine, and similar products (1N NaOH or KOH was used and the solution during standing for 15 minutes was occasionally agitated) hut it was dropped from the fourth (1935) and succeeding editions. Ripper compared his method with the Haas distillation method on ten wines whose SO2 content varied from 42 to 1488 mg. per liter and found the difference between the two to vary from 0 to 5 mg. 

The test method does not purport to identify all individual sulfur components. Detector response to sul r is linear and essentially equimolar for all sulfur compounds within the scope (1.1) of this test method thus both unidentified and known individual compounds are determined. However, many sulfur compounds, for example, hydrogen sulfide and mercaptans, are reactive and their concentration in samples may change during sampling and analysis. Coincidently, the total sulfur content of samples is estimated from the sum of the individual compounds determined however, this test method is not the preferred method for determination of total sulfur. 

Visual examination of the sample may be sufficient to show the presence of a surfactant. If the sample foams on being shaken, or if an aqueous fluid wets the sides of its container without droplet formation, or if an emulsion forms upon addition of water and hydrophobic solvent, it can be presumed that a surfactant is present. More evidence is obtained by measuring the surface tension of the solution, either directly or electrochemi-cally. An often-overlooked method for detecting additives is elemental analysis. Frequently, an inexpensive determination of total sulfur or nitrogen content is sufficient to provide confirmation of the presence of an anionic or cationic surfactant. 

The feed and products were characterized in order to determine the total sulfur content and distillation curve. Sulfur content in the feedstock and products was determined with HORIBA equipment (SLFA-2100) by using the standard ASTM D-4294 method. The variation coefficient of the analysis with this instrument is 0.006%. 

Active matter (anionic surfactant) in AOS consists of alkene- and hydroxy-alkanemonosulfonates, as well as small amounts of disulfonates. Active matter (AM) content is usually expressed as milliequivalents per 100 grams, or as weight percent. Three methods are available for the determination of AM in AOS calculation by difference, the two-phase titration such as methylene blue-active substances (MBAS) and by potentiometric titration with cationic. The calculation method has a number of inherent error factors. The two-phase titration methods may not be completely quantitative and can yield values differing by several percent from those obtained from the total sulfur content. These methods employ trichloromethane, the effects from which the analyst must be protected. The best method for routine use is probably the potentiometric titration method but this requires the availability of more expensive equipment. 

The analysis of phosphates and phosphonates is a considerably complex task due to the great variety of possible molecular structures. Phosphorus-containing anionics are nearly always available as mixtures dependent on the kind of synthesis carried out. For analytical separation the total amount of phosphorus in the molecule has to be ascertained. Thus, the organic and inorganic phosphorus is transformed to orthophosphoric acid by oxidation. The fusion of the substance is performed by the addition of 2 ml of concentrated sulfuric acid to — 100 mg of the substance. The black residue is then oxidized by a mixture of nitric acid and perchloric acid. The resulting orthophosphate can be determined at 8000 K by atom emission spectroscopy. The thermally excited phosphorus atoms emit a characteristic line at a wavelength of 178.23 nm. The extensity of the radiation is used for quantitative determination of the phosphorus content. 

In this method sulfur is determined by carbon tetrachloride extraction of the residue remaining after the ether, water, and acid extractions of the sample. The sum of the sulfur found here and by the ether extraction procedure (Standard Method No 30) represents the total sulfur content. The sulfur removal is followed by acetone extraction for the determination of NC (Nitrocellulose)... 

The latexes were ion-exchanged with Dowex 50W(H+) resin and the Dowex 50W(H+)-Dowex 1 (0H ) mixed resin in combination with the Dowex 50W(Na" ")-Dowex 1 (0H ) resin, and the ion-exchanged samples were titrated conductometrically. The samples treated were the latex, the aqueous serum, the latex particles separated from the serum, and the latex particles swollen or dissolved in 80 20 dioxane-water mixture. The total oxygen content was determined by neutron activation and the total sulfur content by X-ray fluorescence. Material balances of acrylic or methacrylic acid found in the serum, on the particle surface, and inside the particle agreed with the amount added to within 5-10%. 

In order to determine the rate equation for hydrodesulfurization, a semi-logarithmic plot of the total sulfur content with time was made (Figure 2). The plot indicated two independent first-order reactions with greatly different rate constants. This is in agreement with the findings of Gates, et al. (7) and Pitts (3). A procedure similar to that of Pitts (3 ) was used to describe the hydrodesulfurization kinetics. The rate expression is given below ... 

A numerical search routine was applied to determine the value of K and A E. Figure 4 compares the theoretical curve with the experimental data and represents a satisfactory curve fit. The total sulfur content and SRC sulfur content for hydrotreated product were plotted (Figure 5), and a linear relationship was shown to exist between them. 

Sampling. Two sets of vibracores were collected at each site. A previously collected set was used, along with other cores in each area, to determine stratigraphic and sedimentologic relationships. Color, texture, and structure were used to establish different lithofacies, which were later verified or modified using x-ray radiography. Ash and total sulfur contents were then determined for channel samples of these units. 

Solid phase chemical analyses included determination of total organic C content, and the distribution of S between iron monosulfides (acid-volatile sulfur or AVS) and pyrite (the difference between total reducible sulfur and AVS). Total organic carbon was measured coulometrically following combustion at 1050°C (7). Acid-volatile sulfur and total reducible sulfur analyses followed the procedure of Canfield et al. (8). A microbiological assay of the abundance of sulfate reducing bacteria was performed according to (9). 

Various bituminous coals were demineralized by an experimental two-step leaching process in which the ball-milled coals were first treated with a hot alkaline solution and then with a dilute mineral acid. Different alkalis and acids were studied to determine their relative effectiveness. In addition, the effects of alkali concentration, treatment temperature, and treatment time were evaluated. Under the best conditions, the process reduced the ash content of the coals by 85-90% and the total sulfur content by 70-90%. As the temperature of the alkaline treatment was raised from 150 to 345 C, the removal of sulfur increased greatly whereas the recovery of organic matter declined. When a 1 M sodium carbonate solution was employed for the treatment, the recovery of organic matter was 91-97% for various coals treated at 250 C and 79-89% for the same coals treated at 300 C. 

The total sulfur content of the coal samples was determined by the Eschka method. The sulfate sulfur content of the test samples was determined by extraction of a one-gram sample with dilute hydrochloric acid followed by turbidimetric determination of sulfate (24). The pyritic sulfur content was determined by extraction of the weighed coal samples with 2N nitric acid followed by titrimetric or atomic absorption determination of iron in the extract. (25). 

The amount of reduction of the chromium may be determined by oxidizing aliquot portions of the above solution and determining the total chromium content. The oxidation is effected by acidifying the sample with 10% sulfuric acid and heating nearly to boiling. A small crystal of silver nitrate and approximately 2 g. of ammonium peroxydisul-fate are added for every 50 ml. of solution. The treated solution is evaporated to one-half its former volume, cooled, apd diluted to 50 ml. The remainder of the procedure is the same as that used for hexavalent chromium. 

In a third set of experiments, -38 pm pyrite particles were leached with hot alkaline solutions to study the conversion of iron pyrite to iron oxide and soluble sulfur species. In each experiment, 5 g. of acid-cleaned pyrite was leached with 120 ml. of alkaline solution for 1 hr. In addition to analyzing the solid residue by XRD, the total sulfur content of the leachate was determined in order to estimate pyrite conversion. 

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