Total sulfur analysers

Sulfur content is often measured for industrial controls by X-ray fluorescence because the samples usually form part of a series, which may be compared with very similar standards. Yet, for organically bound sulfur compounds that can be destroyed by combustion in a current of oxygen, the measure is based upon the volume of sulfur dioxide (SO2) formed in an instrument similar to that described previously. Three main procedures of quantification co-exist with which the other gases of combustion do not interfere  

---

Ash and Total Sulfur Analyses. Samples were removed from the specimens and submitted for ash and total sulfur analysis to Schwartzkopf Microanalytical Laboratory, Woodside, N.Y. 11377. For ashing, samples were burned under oxygen at 900-1000°C for ca one half hour. For sulfur, samples were treated with potassium metal to convert sulfur to sulfides, followed by conversion to methylene blue for spectrophotometrlc analysis (at 670 nm). Except for very small samples (less than 0.2mg), values for ash and sulfur have an uncertainty of ca 10% of the reported values. 

Table III lists the results of pH measurements, ash, and total sulfur analyses grouped according to sample color.

A. Total sulfur analyses showed greater levels (2-9x) than could be accounted for by the sulfur In the proteinaceous backbone of the silk. 

Two bituminous coals of moderate ash content were chosen for this paper to illustrate this method of determining coal-mineral association. The first sample was an Upper Freeport coal with 1.3% moisture, 9.88% ash, and 1.56% total sulfur. The second sample was an Indiana No. 3 coal having 10.5% moisture, 7.35% ash, and 4.26% total sulfur. Both coals had been precleaned at a coarse particle size, ground to minus 325 mesh (44 ym), and then separate samples were cleaned by float-sink and by froth flotation techniques, as described elsewhere [5]. Analyses of the feed coals are included in Table I. 

H/C = atomic hydrogen-to-carbon ratio V = vitrinite content of coal VM volatile matter St = total sulfur TRM = total reactive macerals The adequacies of these reactivity correlations, expressed as a percentage of the total variation in the data set explained by the model, were 80.0%, 79.2%, and 47.5% respectively. A later paper in the series (21) concentrated on the development of reactivity correlations for a set of 26 high volatile bituminous coals with high sulfur contents, and extended the models previously developed in include analyses of the liquefaction products and coal structural features. These structural features included the usual... 

Analyses and calorific values are determined on a mineral-matter-free basis by the Parr formulas (ASTM D-388), with corrections for pyrite and other mineral matter. The amount of pyrite is taken to be that equivalent to the total sulfur of the coal, which despite the potential error has been found to correlate well in studies of mineral matter. The remaining mineral matter is taken to be 1.08 times the weight of the corresponding (iron-oxide-free) ash ... 

Examples of soil analyses carried out by Landers et al. [65] for acid-digestible inorganic sulfur (HCI-S) non-sulfate inorganic sulfur (Zn-HCI-S) non-carbon-bonded sulfur (HI-S), as well as total sulfur, sulfate and carbon-bonded sulfate (C-O-SO3), are shown in Table 6.3. 

Chloride, sulfate, and pH analyses of pore solutions from the three sites are shown in Figure 6. Figure 7 depicts organic matter, total sulfur and total iron for the same cores and Figure 8 shows data on forms of sulfur. 

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). 

Elemental analyses of these samples were obtained by energy dispersive x-ray spectrometry (EOS). Total sulfur, ash, and pH of the samples is also reported, and colorants were determined. The presence of mordants, weighting materials, and colorants is discussed with reference to the embrittlement of the silk. The connection between fiber deterioration and color is discussed as well as the effects of contemporary manufacturing treatments on the present fiber condition. 

Except for a single example (012) the sulfur analyses were substantially higher than values reported for untreated silk, l.e the sulfur accountable to the presence of cysteine or methionine In the fibroin chain of silk. Values obtained for total sulfur ranged from ca 2 - 9 times the value expected from untreated silk. The single low value found for a blue sample was very close to that expected for untreated silk the highest value was for a white sample. Most of the samples (twenty-five of thirty-four)had a sulfur % of 0.35 0.12, ca 5 times the amount present in untreated silk. 

The total sulfur concentration of the coal charged to the reactor and that of the solid product were determined by use of a Fischer Total Sulfur Analyzer. Liquids were analyzed on a Perkin Elmer Sigma 3 gas chromatograph and gas analyses were performed on a Varian Model 3400 gas chromatograph. 

Solid analyses (Moisture free) ISGS Std. Coal 1 (moisture free) % Total Sulfur 4.23b 2.69 2.64 2.94 1.95... 

The results in terms of final sulfur values and pyrite removal are given in Table VIII. Note that pyritic removal computed from either sulfur forms analyses or the diflFerence in total sulfur between processed and untreated coal (Eschka analysis) resulted in essentially identical values of 93-100%. This corresponds to total sulfur removal of 40-70%, depending on the organic sulfur content of the coal. The observation of greater than 100% removal is a result of cumulative error in analysis and the removal of small amounts of sulfate (0.02-0.04%). Presently, these experiments are being duplicated using ferric sulfate, and preliminary analysis indicates the same results. 

The feedstocks (straight-mn naphtha (SRN) and a blend of SRN and hydrocracked naphtha) and hydrotreated products were analysed by ASTM methods for density, carbon, hydrogen, hydrocarbon and boiling point distribution. Total sulfur was determined by ASTM D-4045 method, mercaptan sulfur by the potentiometric method (ASTM D-3227 and UOP-212), disulfides by the UOP-202 method, polysulfides by polarography [1], and elemental sulfur by the UOP-286 method. The Perkin-Elmer gas chromatograph (Model 8700), equipped with a flame photometric detector (GC/FPD) and a DB-1 fused silica capillary column (30 m x 0.53 mm), was used for identification of individual sulfur compounds [2-6]. The sensitivity of the GC/FPD technique was maximized by optimizing the gas flow rates and temperature programming as presented elsewhere [1]. 

At the Big Five Pilot wetland in Idaho Springs, the ultimate objective is removal of the heavy metals from the mine drainage. The fate of sulfur in the system is important to this removal. The pilot system consists of three 18.6 m cells and a typical metal mine drainage flows into each cell at the rate of 200 gal/min (13). One of the processes that can be quite important for metal removal is the reduction of sulfate to bisulfide catalyzed by sulfate-reducing bacteria. To monitor whether this process was working, analyses of total sulfur and the forms of sulfur in the substrates was requested by a SAS designating ASTM method D-2492 (14). The results of the requested analyses are given in Table VI. 

It has been found that when the mixture is heated at such a high temperature, a considerable amount of sulfur trioxide is expelled from the melt, while phosphorus pentoxide is not expelled. Chemical analyses of the reaction products revealed that 63.5 and 80.8% of the total sulfur was expelled as sulfur trioxide when prepared at 1300 or 1400°C., respectively. If one assumes that no compounds with S-O-P linkages are produced in the sample, the reaction can be represented by ... 

Most of the inorganic sulfate assimilated and reduced by plants appears ultimately in cysteine and methionine. These amino acids contain about 90% of the total sulfur in most plants (Allaway and Thompson, 1966). Nearly all of the cysteine and methionine is in protein. The typical dominance of protein cysteine and protein methionine in the total organic sulfur is illustrated in Table I by analyses of the sulfur components of a lower plant (Chlorella) and a higher plant (Lemna). Thede novo synthesis of cysteine and methionine is one of the key reactions in biology, comparable in importance to the reduction of carbon in photosynthesis (Allaway, 1970). This is so because all nonruminant animals studied require a dietary source of methionine or its precursor, homocysteine. Animals metabolize methionine via cysteine to inorganic sulfate. Plants complete the cycle of sulfur by reduction of inorganic sulfate back to cysteine and methionine, and are thus the ultimate source of the methionine in most animal diets (Siegel, 1975). 

The Mitsubishi TSX-10 halogen-sulfur analyser expands the technology of the TOX-10 to include total chlorine and total sulfur measurement. The model TSX-10, which consists of the TOX-10 analyser module and a sulfur detection cell, measures total sulfur and total chlorine in liquid and solid samples over a sensitivity range of milligrams per litre to a percentage. Dohrmann also produces automated sulfur and chlorine analyser (models MCTS 130/120). This instrument is based on combustion microcoulometric technology. 

---