Sulfur Content In Samples Research Articles

Prediction of sulfur content in diesel fuel using fluorescence spectroscopy and a hybrid ant colony - Tabu Search algorithm with polynomial bases expansion

It is widely accepted that feature selection is an essential step in predictive modeling. There are several approaches to feature selection, from filter techniques to meta-heuristics wrapper methods. In this paper, we propose a compilation of tools to optimize the fitting of black-box linear models. The proposed AnTSbe algorithm combines Ant Colony Optimization and Tabu Search memory list for the selection of features and uses l1 and l2 regularization norms to fit the linear models. In addition, a polynomial combination of input features was introduced to further explore the information contained in the original data. As a case study, excitation-emission matrix fluorescence data were used as the primary measurements to predict total sulfur concentration in diesel fuel samples. The sample dataset was divided into S10 (less than 10 ​ppm of total sulfur), and S100 (mean sulfur content of 100 ​ppm) groups and local linear models were fit with AnTSbe. For the Diesel S100 local models, using only 5 out of the original 1467 fluorescence pairs, combined with bases expansion, we were able to satisfactorily predict total sulfur content in samples with MAPE of less than 4% and RMSE of 4.68 ​ppm, for the test subset. For the Diesel S10 local models, the use of 4 Ex/Em pairs was sufficient to predict sulfur content with MAPE 0.24%, and RMSE of 0.015 ​ppm, for the test subset. Our experimental results demonstrate that the proposed methodology was able to satisfactorily optimize the fitting of linear models to predict sulfur content in diesel fuel samples without need of chemical of physical pre-treatment, and was superior to classic PLS regression methods and also to our previous results with ant colony optimization studies in the same dataset. The proposed AnTSbe can be directly applied to data from other sources without need for adaptations.

Combination of Microwave and Ultrasonic Irradiations as a Pretreatment Method to Produce Ultraclean Coal

Coal samples from concentrate of Shahroud coal preparation plant with an ash content of 13.8% and a total sulfur content of 1.89%, without pretreatment and also with pretreatment by microwave irradiation, ultrasonic waves, and microwave followed by ultrasonic (microwave- ultrasonic), was leached with HF and then HNO3 to produce ultraclean coal (UCC) in a batch reactor. Irradiation pretreatments, in the order of microwave-ultrasonic > ultrasonic > microwave had positive effects on acid leaching with HF, especially for coarse size fractions and early in the leaching process. After HF leaching, the HNO3 complementary leaching was more effective on the microwave-ultrasonic pretreated sample, where, after processing, 95.5% ash content of the sample was removed. A comparison between sulfur content of samples before (1.89%) and after leaching (HF followed by HNO3) shows that the sulfur content of nonpretreated sample decreased to 1.26%, whereas this reduction for microwave-ultrasonic pretreated sample was more noticeable by 0.8%. The results indicated that microwave-ultrasonic irradiation can be considered as the most effective pretreatment method in the chemical leaching of coal to produce UCC.

Effects of Zr/Ti molar ratio in SO2−4/ZrO2-TiO2 calcined at different temperatures on its surface properties and glucose reactivity in near-critical methanol

Effects of Zr/Ti molar ratio in SO2−4/ZrO2-TiO2 solid acid catalyst calcined at different temperatures on its surface properties and catalytic activity were thoroughly investigated in this paper. The physicochemical characteristics of prepared samples were determined by N2 adsorptiondesorption, XRD, NH3-TPD and XPS techniques, respectively. It was found that the crystallization temperature of the samples increased after the combination of ZrO2 and TiO2; and phase transformations from the anatase to the rutile of TiO2 species and the tetragonal to the monoclinic of ZrO2 species were effectively suppressed at higher temperature. The sample with a Zr/Ti molar ratio of 3/1 calcined at 450 °C showed the highest surface area and the most acid sites among all the tested samples. The acid site densities of samples were relatively closed to each other if they were calcined at the same temperature, however, decreased with the calcination temperature. The result indicates that the sulfur content in samples is a crucial factor to control the acid site density. Calcining the sample at 650 °C and higher temperatures resulted in a significant desorption of sulfate ion on the samples. The synthesized samples were evaluated as a potential catalyst for glucose conversion under the near-critical methanol conditions (200 °C/4 MPa). The results suggested that the relatively weaker acid sites of the catalyst were more favorable for the accumulation of methyl glucosides, while the moderate acid sites were responsible for the formation of methyl levulinate. The catalytic activity for methyl levulinate production almost increases linearly with the catalyst acid site density. The catalyst deactivation is due to the loss of sulfate ion and the two catalysts with Zr/Ti molar ratios of 3/1 and 1/3 could effectively alleviate the deactivation caused by sulfate solution in the reaction medium and can be reused after calcination with the reuse rate of over 90% in terms of the methyl levulinate selectivity.

A geostatistical approach to predicting sulfur content in the Pittsburgh coal bed

The US Geological Survey (USGS) is completing a national assessment of coal resources in the five top coal-producing regions in the US. Point-located data provide measurements on coal thickness and sulfur content. The sample data and their geologic interpretation represent the most regionally complete and up-to-date assessment of what is known about top-producing US coal beds. The sample data are analyzed using a combination of geologic and Geographic Information System (GIS) models to estimate tonnages and qualities of the coal beds. Traditionally, GIS practitioners use contouring to represent geographical patterns of “similar” data values. The tonnage and grade of coal resources are then assessed by using the contour lines as references for interpolation. An assessment taken to this point is only indicative of resource quantity and quality. Data users may benefit from a statistical approach that would allow them to better understand the uncertainty and limitations of the sample data. To develop a quantitative approach, geostatistics were applied to the data on coal sulfur content from samples taken in the Pittsburgh coal bed (located in the eastern US, in the southwestern part of the state of Pennsylvania, and in adjoining areas in the states of Ohio and West Virginia). Geostatistical methods that account for regional and local trends were applied to blocks 2.7 mi (4.3 km) on a side. The data and geostatistics support conclusions concerning the average sulfur content and its degree of reliability at regional- and economic-block scale over the large, contiguous part of the Pittsburgh outcrop, but not to a mine scale. To validate the method, a comparison was made with the sulfur contents in sample data taken from 53 coal mines located in the study area. The comparison showed a high degree of similarity between the sulfur content in the mine samples and the sulfur content represented by the geostatistically derived contours.

Petrography, palynology and depositional environments of the early Miocene Oberdorf lignite seam (Styrian Basin, Austria)

An early Miocene (Ottnangian) lignite seam up to 36 m thick occurs in the Oberdorf trough at the northwestern margin of the Styrian Basin. It forms part of the fluvial Köflach–Voitsberg Formation. Petrographic and palynologic data, together with ash yield and sulphur content of samples from two boreholes and two surface profiles have been used to study vertical and horizontal coal facies variations. Numerous partings and a high ash yield show that the lignite originated in a topogenous mire. Petrographic indices and palynological data suggest a wet-forest swamp paleo-environment. A fluvial main parting with channel sediments at the eastern margin of the Oberdorf trough and overbank sediments in its central part splits the lignite into a lower and an upper seam. The lower seam consists of a lower high-ash part with frequent splittings and a higher low-ash part. The upward decrease in number and thickness of silty–clayey partings, interpreted as crevasse splay deposits, reflects the withdrawal of the fluvial sediment source. Coal composition is characterized by an upward increase in (detro-)xylitic coal and in tissue preservation. A good correlation between tissue preservation and percentages of Taxodiaceae–Cupressaceae pollen suggests that this is mainly a result of an increasing contribution of decay-resistant gymnosperms (conifers). The upper seam is also ash-rich. Abundant inertinite at the eastern margin of the Oberdorf trough is related to fire episodes inside or outside the mire. Main features of the upper seam in the central basin are an upward increase in tissue preservation and in percentages of Taxodiaceae–Cupressaceae pollen. High sulphur contents in the fresh-water lignite are a result of a concentration of sulphate-rich waters above the impermeable floors of the lower and upper seams. Carbonate-rich surface waters from the Graz Palaeozoic and Raasberg-Sequence raised the pH value and controlled sulphur (and ash) contents in those parts of the lower seam, which are uninfluenced by the basal sulphur enrichment. Palynomorph spectra are dominated by Taxodiaceae–Cupressaceae pollen and pollen from plants living in a mixed mesophytic forest. Pollen from aquatic and reed plants are rare. The ratio between arctotertiary and paleotropic pollen is close to one and supports the early Miocene age of the lignite. The detected pollen spectra point to warm–temperate subtropic and humid conditions.

Comparative biomonitoring of atmospheric quality in five zones of Córdoba city (Argentina) employing the transplanted lichen Usnea sp.

The lichen Usnea sp. was transplanted to five zones plus a control one in the city of Córdoba, with different levels of industrial and traffic pollution. The chlorophyll a+b, hydroperoxy conjugated dienes, malondialdehyde concentration, chlorophyll b/chlorophyll a, phaeophytin a/chlorophyll a, DW/FW ratio and sulfur accumulation were determined. A pollution index (PI) was calculated to compare the air quality of the zones biomonitored. It was observed that the content of chlorophylls a+b increased parallel to the level of pollutants emitted by traffic, but at the same time, there was an increase in the degradation of chlorophyll a. These results indicate that chlorophylls would be affected by air pollutants emitted by traffic and as a compensatory mechanism the lichen would increase their synthesis. Significant differences were observed in hydroperoxy conjugated dienes concentration and sulfur content in samples transplanted to high traffic level sampling points. At the same time, a higher sulfur content was observed in lichens transplanted to sampling points located in downtown, in neighboring areas or with high industrial level, suggesting an additive effect of industrial with traffic pollutants. PI results allow us to differentiate areas with different air quality in the city, the highest pollution levels being observed in the downtown area with high traffic. Two other areas near downtown with high traffic are also in this category. Except for downtown and a far away zone with high industrial density, the other areas showed higher PIs at high traffic sites. The lowest PIs were observed in the control zone and at the low traffic sampling points.

Petrographic composition and depositional environments of the Pliocene Velenje lignite seam (Slovenia)

A Pliocene lignite seam up to 160 m thick occurs in the Velenje depression in northern Slovenia. It forms part of a non-marine transgressive sequence. Petrographic data, together with ash and sulphur content of samples from two boreholes (one located in the central, and the other in the marginal part of the seam) have been used to study vertical and lateral coal facies variations. In the central part, the lignite seam overlies fluvial sediments. Facies critical macerals and petrographic indices suggest that the lower (ash rich) part of the seam (unit I) accumulated in a wet forest swamp in an alluvial plain setting. Later this environment was replaced by a dry (telmatic) forest swamp (unit IIa). According to our interpretation, a decrease in tree density in units IIb and IIc reflects a change to a bush moor. The transition from unit II to unit III is characterized by a rapid water table rise, which resulted in the establishment of a wet (limnotelmatic) forest swamp. Within unit III, the tree density decreases and the degree of gelification increases towards the top of the seam suggesting a transition to a fen type environment. Another rapid water table rise ended peat formation in the eutrophic, topogenous mire, and established open lacustrine conditions. A calcium rich environment resulted in high pH values and is responsible for high sulphur lignites (up to 4% on a dry basis). In the upper part of the seam, the pH values were controlled by the amount of the inflowing lacustrine water. Only thin, ash-rich topotelmites accumulated along the northern margin of the mire. There, the seam originated in a wet forest swamp and was separated by limnic and fluvial sediments from other organic rich horizons. Due to its closer vicinity to the pre-Tertiary carbonates, the depositional environment was probably even more alkaline. Therefore, the lignite shows a higher degree of gelification and is even more sulphur rich (up to 5.5% on a dry basis).

Chemical response of the lichen Punctelia subrudecta (Nyl.) Krog transplanted close to a power station in an urban-industrial environment

The lichen Punctelia subrudecta (Nyl.) Krog was transplanted to 22 biomonitoring sites in a northwestern area of Córdoba city, Argentina and tested for chlorophyll a, chlorophyll b, phaeophytin a, soluble protein, hydroperoxy conjugated dienes (HPCD), malondialdehyde (MDA) concentration and sulphur accumulation. A pollution index (PI) was calculated for each biomonitoring site. The biomonitoring sites were set according to (1) traffic levels, (2) industrial density and (3) distance of the power station close to each site. The biomonitor's chemical response was associated with industries as well as power stations. Significant differences were observed in sulphur content, MDA concentration and PI values in lichen material transplanted to sites with different industrial densities. The higher values for these parameters were found at sites with high industrial levels. At the same time, significant differences were detected for sulphur content in samples at different distances from the power station, with higher accumulation in samples located far from the power plant. For MDA concentration, effect of different levels of industrial density was observed only at points close to the power station, probably because of higher levels of humidity near the power plant. For PI significantly higher values were observed in samples at points far from the power station and with high industrial density. This shows the additive effect of the principal emission sources that act on the response of P. subrudecta to air pollutants.

Variability in Btu, Ash, and Sulfur Content of Northeastern Ohio Peat Deposits: ABSTRACT

Northeastern Ohio contains over 24,460 acres (9,898 ha.) of peatlands, some of which combine relatively low ash and sulfur with Btu values comparable to those of Ohio coal. This combination of properties makes these deposits a potential local fuel source. Eighteen bogs developed in nine different substrate units were sampled to determine the range of within-bog and between-bog variability with respect to Btu, ash, and sulfur content. The substrate units are based on glacial and soil maps of the area. Two bogs were sampled from within each substrate unit. For each unit, one bog was sampled laterally at two localities at a depth of 6.5 ft (2 m), and a second bog was sampled vertically at one locality at depths of 6.5 and 20 ft (2 and 6 m). A total of 36 samples was collected and analyzed for Btu, ash, and sulfur. The data show a strong negative correlation between ash and Btu. Ash content can explain 99.2% of the Btu values in the peat samples and can be used to predict Btu values to within ±200 Btus. There are statistically significant differences in Btu, ash, and sulfur content in samples from different substrate units. Bogs in the substrate units, which included the Kent-Lavery Drift end moraine and kame facies, are generally high in Btu and low in ash and sulfur. An attempt was made to identify the combination of variables present locally in the nine substrate units which best explained their Btu content. Stepwise multilinear regression analysis of these variables shows that mean annual precipitation and drainage area explain 72% of the variation in the peat Btu values. End_of_Article - Last_Page 1166------------

Determination of sulphur in steel by a modified combustion procedure and coulometric titration

The quantitative determination of sulphur in steel by the combustion method is inefficient as the sulphur content of samples indicated by this method is lower than that given by other methods because sulphur trioxide occurring in the combustion furnace tends to condense in the piping. An attempt has been made to establish how this sulphur trioxide condensation occurs, and a unique, automatic circulation type of adsorption method has been devised to ensure complete collection of gaseous sulphur occurring in the combustion. For this purpose, a practical sulphur analyser with high sensitivity and accuracy has been developed in which and automatic coulometric titrator and a high-frequency induction furnace are combined. Standard samples of various types of iron and steel analysed with this apparatus showed that the results agreed well with their standard values.