Increase In Sulfur Content Research Articles

Effect of nickel promoter on solvent‐free sulphated zirconia catalyst for the esterification of acetic acid with n‐butanol

AbstractA simple solvent‐free preparation method was used to synthesize sulphated zirconia catalyst with various amounts of nickel promoter. This research investigated the effect of nickel addition to sulphated zirconia on the catalyst performance in esterification of acetic acid (a bio‐oil model) with n‐butanol. The results show that the addition of nickel contributed to the increase of sulphur content that bonded with nickel, the increase of thermal stability of the catalysts, and the formation of additional sulphate groups, and thus resulted in better catalytic performance compared to sulphated zirconia without nickel. More nickel being added resulted in a significant increase of acetic acid conversion; with 0.05 mol/mol nickel amount, the conversion was 97.93 %. This result represents a dramatic increase of about 2 and 3 times compared to the conversions of non‐nickel sulphated zirconia catalyst and non‐catalyst reactions, respectively.

Influence of different S/Se ratio on the properties of Cu2Sn(S x Se1-x )3 thin films fabricated by annealing stacked metal precursors

Cu2Sn(SxSe1-x)3 (CTSSe) thin films were successfully synthesized by annealing process from stacked precursors prepared on soda lime glass substrates by radio frequency magnetron sputtering technique. The structural, morphological, optical and electrical properties in wide composition range (0 ≤ x ≤ 1) have been investigated. Energy dispersive X-ray measurement indicates that the ratio of sulfur and selenium in thin films could be tuned. X-ray diffraction patterns demonstrate that the lattice constant decreases linearly with the increase in sulfur content. Raman spectra analysis confirms that the dominant peaks present linear variation with x value. Optical characterization reveals that the band gap energy can be tuned monotonously from 0.60 to 0.92 eV. Further electrical measurement results show that all samples are p-type semiconductor and the mobility of CTSSe decreases when S replaces gradually Se.

A Coupled Thermodynamic Model for Prediction of Inclusions Precipitation during Solidification of Heat-resistant Steel Containing Cerium

A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established. Then the model was validated by the SEM analysis of the industrial products. The type and amount of inclusions in solidification structure of 253MA heat-resistant steel were predicted by the model, and the valuable results for the inclusions controlling in 253MA steel were obtained. When the cerium addition increases, the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253MA steel and the precipitation temperature of SiO2 and MnS decreases. The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2S, Ce3S4, and MnS as the sulfur content increases. The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases. There is only a small quantity of inclusions containing cerium in 253MA steel with high cleanliness, i.e., low oxygen and sulfur contents. By contrast, a mass of SiO2, MnS and Ce2O2S are formed in steel when the oxygen and sulfur contents are high enough. The condition that MnS precipitates in 253MA steel is 1.2w[O] + w[s]>). 01% and SiO2 precipitates when 2w[O]+w[s]>0.017% (w[S]<0.005%) and w[O]>0. 006% (w[S]>0. 005%).

Tribotechnical properties of deposited metal of 50Kh9S3G type with increased sulphur content

The Paton Welding Journal, 2014, №12. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

The cyclic oxidation behaviour of Ni-based superalloy GTD-111 with sulphur impurities at 1100 °C

The effect of sulphur on the cyclic oxidation of Ni-based superalloy GTD-111 was investigated. A cyclic oxidation experiment was performed for up to 200 cycles of 1h exposure at 1100°C. Even at the initial stage of 15 cycles, porosity increased with increasing sulphur content. The formation of pores along Cr2O3 layer grain boundaries was particularly pronounced. Increased porosity leads to an increase in spallation, which results in accelerated depletion of Cr and Al. As a result, continuity of an Al2O3 layer and cyclic oxidation resistance reduced with increasing sulphur content.

Formation of CuIn(SxSe1−x)2 microcrystals from CuInSe2 nanoparticles by two step solvothermal method

Here we introduced a two-step reaction to synthesize highly crystalline CuIn(S1−xSex)2 (CuInSSe) microcrystals from CuInSe2 nanocrystals. CuInSSe micro particles can be obtained without toxic selenization or sulfurization process and the composition of sulfur and selenium can be easily controlled by varying the amount of precursor at different stages of the reactions. This synthetic route allows a technique that is simple and non-toxic together with the possibility of tuning the composition. XRD, HRTEM and SAED analysis of the final product confirmed the pure phase formation of CuInSSe. EDAX analysis shows the compositions of the final product matched with CuInSSe and the compositions of the product can tune by the reaction parameter. UV–Vis absorption spectra reveals a clear blue shift due to an increase in band gap with the increase of sulfur content. Initial photocurrent response suggests its possibility to be used as absorber materials in thin film solar cells.

Activated carbon with ultrahigh specific surface area synthesized from natural plant material for lithium–sulfur batteries

Porous activated carbon with a ultrahigh specific surface area (3164 m2 g−1) and large pore volume (1.88 cm3 g−1) was prepared from waste litchi shells with channel-like macropores via a KOH activation method. The macroporous structure of litchi shells is believed to be conducive to distribute the activation agent, which enables sufficient activation. The as-prepared activated carbon was developed as a conducting framework for lithium–sulfur battery cathode materials. The resulting activated carbon/sulfur composite cathode possesses a high specific capacity, good rate capability, and long-term cycling performance. At 200 mA g−1 current density, the initial discharge capacity of the activated carbon/sulfur composite cathode with 60 wt% sulfur content is 1105 mA h g−1. At a current density of 800 mA g−1, the activated carbon/sulfur composite cathode shows 51% capacity retention over 800 cycles with a fade rate of 0.06% per cycle. The coulombic efficiency of the cell remains at approximately 95%. By adding LiNO3 in the electrolyte, the activated carbon/sulfur composite electrode tested at 800 mA g−1 shows a high coulombic efficiency (>99%). The activated carbon/sulfur composites exhibited similar capacity value and cycling trends with an increase in sulfur content from 60% to 68%. The good electrochemical performance can be attributed to the excellent structural parameters of the activated carbon. The ultrahigh specific surface area and large pore volume not only enhances the sulfur content but also ensures dispersion of elemental sulfur in the conducting framework, thereby improving sulfur utilization. The small nanopores of the activated carbon can effectively inhibit the diffusion of polysulfides during the charge/discharge process.

Insight into insulator-to-metal transition of sulfur-doped silicon by DFT calculations.

Using density functional theory calculations, the mechanism of insulator-to-metal transition of S-doped Si has been systematically investigated. The calculated crystal structure indicates that the gentle lattice distortion is caused by sulfur doping, and this doping effect is gradually weakened with the increase of sulfur concentration. Two distinct impurity energy levels in the band gap are induced by sulfur doping, and their position and width are linearly varying along with the increase of sulfur concentration. Owing to the overlap and dispersion of these impurity energy levels, the insulator-to-metal transition occurs at the sulfur concentration of 2.095 × 10(20) cm(-3), which is consistent with the experimental measurement. Moreover, the defect states related with sulfur doping show delocalization features and are more outstanding at the higher sulfur concentration. The calculated results suggest that S-hyperdoped Si is a suitable candidate for intermediate band solar cells.

Stabilizer-free CdSe/CdS core/shell particles from one-step solution precipitation and their application in hybrid solar cells

CdSe/CdS core/shell nanoparticles were synthesized in aqueous solution by one-step process. CdSe precipitates were first obtained at 80 °C in a solution of cadmium chloride, sodium citrate, ammonia and sodium selenosulfate. After 4 h of reaction, the solution with CdSe products was cooled to 60 °C and thiourea (TU), a sulfur precursor, was added while stirring. The amount of the TU solution added was 2, 5 and 10 mL, and the obtained products were named as CdSe/CdS-2, CdSe/CdS-5 and CdSe/CdS-10, respectively. It is observed that CdSe core particles had predominantly a crystalline cubic structure, and the addition of TU in the CdSe solution led to the formation of a very low concentration of hexagonal crystalline phase of CdS whose intensity increased with the amount of TU. The energy-dispersive X-ray spectroscopy in a scanning electron microscope indicated an increase of sulfur concentration in CdSe/CdS products as a function of the amount of TU solution. The presence of CdS-like morphology on the surface of CdSe/CdS particles was also evident. Photoluminescence emission spectra of the CdSe/CdS particles exhibited an increasing CdS emission as the volume of TU solution increased. The photovoltaic performance of solar cells based on CdSe/CdS particles and poly(3-hexylthiophene) (P3HT) suggested that the CdSe particles should be surrounded by CdS because of the similarity between the current–voltage curves of CdSe/CdS/P3HT heterojunctions and that of CdS/P3HT solar cells.

Polioencephalomalacia in ruminants caused by excessive amount of sulphur - a review

Abstract Polioencephalomalacia as a result of sulphur excess is a growing problem in cattle and sheep, mainly in young, growing animals. It is common in different regions of the world. The disease develops favoured by certain conditions such as sustained provision of feed and water with high sulphur content, use of dietary supplements containing sulphur, and a habitat with high hydrogen sulphide concentration. Pathogenesis of the disease is complex, but very important are oxidative-antioxidative imbalance, dysfunction of vessels, and secondary cerebral cortex ischaemia as a result of direct and/or indirect action of sulphur metabolites, namely hydrogen sulphide, sulphides, and sulphites. Clinical signs and changes in the cerebral cortex in the form of degenerative necrotic lesions are similar to those observed in polioencephalomalacia caused by vitamin B1 deficiency, and lead and salt intoxication. Highly increased sulphur content (more than 0.3-0.4 of dry matter) in the diet is the basis for differential diagnosis, as well the high concentration of hydrogen sulphide in gas and sulphides in rumen fluid. In prophylaxis and treatment the most important measure is to limit sulphur intake and in acute cases to neutralise low pH in rumen and administer vitamin B1 injections.

Heterodoped nanoflakes: synthesis and characterization of sulfur‐doped NbSe2 nanoflakes

Doping of NbSe2 with heteroatoms is an effective way to tailor its properties. Here, solid phase synthesis process has been utilized for growing uniform and excellent crystalline nano‐NbSe2 by sulfur dopant during the growing process. The sulfur‐doped mechanism of nano‐NbS2xSe2(1‐x)(x = 0.03∼0.2) has been investigated: the sulfur atoms not only replace the Se position but also intercalate in layer gap by one‐step reaction. In the structure of NbSe2, the sulfur atoms replace the positions of Se atoms and then are located in the empty octahedral positions of van der waals gap between the NbSe2 layers with the increase of sulfur content. The lubrication properties of the as‐prepared NbSe2 and sulfur‐doped NbSe2 powders as additives in HVI1500 base oil were discussed. The lubrication properties of base oil was improved by both NbSe2 and sulfur‐doped NbSe2. Furthermore, the lubrication properties of sulfur‐doped (0.1at%) NbSe2 are better than those of pure NbSe2 in HVI1500 base oil, which could be attributed to their thin laminated structure and the sulfur dopant.

IMPACT OF SULFUR FERTILIZATION ON DIFFERENT FORMS AND BALANCE OF SOIL SULFUR AND THE NUTRITION OF WHEAT IN WHEAT-SOYBEAN CROPPING SEQUENCE IN TARAI SOIL

A field experiment was conducted at farmer's field in Mollisols of Tarai soils in Uttarakhand (India), to assess the direct and residual effect of sulfur fertilization in wheat-soybean cropping sequence. Four levels of sulfur (S; 0, 15, 30, and 45 kg ha−1) were applied to main crop (wheat) along with recommended dose of nitrogen (N), phosphorous (P), and potassium (K). The direct and residual effect of sulfur at highest level showed 27 and 6 percent increase in grain yield of wheat and soybean over control, respectively. The increase in grain yield of wheat was significant at each sulfur level. The direct as well as residual effect of sulfur showed significant increase in sulfur concentration and its uptake by grain and straw except increase in sulfur concentration and uptake by soybean straw. In wheat-soybean cropping sequence, the agronomic efficiency and apparent sulfur recovery decreased with increase in levels of sulfur, but the percent response increased with increasing sulfur application. Different forms of sulfur such as total sulfur, organic sulfur, calcium chloride extractable sulfur, potassium dihydrogen phosphate extractable sulfur, and non-sulfate sulfur in post-harvest soil increased according to sulfur level applied but it decreased under control and also after residual crops. The buildup of sulfur in surface soils was greater than in the deeper soils. Application of sulfur showed the positive sulfur balance and it increased with increase in sulfur level, while it was negative under control. A major portion (46–62%) of applied sulfur contributed to increase in sulfur content of root zone soil followed by unaccounted component (25–40%) and small portion (11–18%) was absorbed by wheat plant as uptake.

Development of Antioxidants Synthesized by Phase Transfer Catalysts for Lubricating Oil

The oxidation stability of lubricating oil has a critical influence on the oil performance during service. In this paper, dibenzyl-S-phenyl thioglyconitrile and other derivatives were prepared by phase transfer catalysts and investigated as antioxidants. These compounds were added to oil in different concentrations. The antioxidants activities of different dosages were evaluated and the mechanism was suggested according to micelle and its thermodynamics. The oxidation of the oil has been carried out at different time intervals. The degradation of the oil has been monitored by total acid formation. Oxidation stability of lube oil was largely affected by sulphur and concentration of aromatic hydrocarbons in oil, with the increased sulphur content increasing oxidation stability. The prepared compounds gave higher oxidation stability than imported compound (IRCANOX L 135-CIBA).

Effect of sulfur additive on density of localized states in nanostructures chalcogenide Se95−xSxZn5 thin films

This paper reports the measurement of space charge limited conduction (SCLC) on the fabricated thin films of Se95−xSxZn5 (0.2≤x≤10) in temperature range 313–353K for the first time. At high electric fields (E∼104V/cm), the current could be fitted into the theory of space charge limited conduction, in case of uniform distribution of localized states in mobility gap. The homogeneity and surface morphology of thin films were assessed by scanning electron microscopy. The crystalline nature of the thin films was confirmed by powder XRD and the crystallite size was calculated using Scherer's formula. The crystallite size and density of localized states were found to increase with the increase of sulfur concentration. DC conductivity and activation energy were calculated and found to decrease and increase respectively, with the increase of sulfur concentration.

Proximate, chemical compositions and sulphur concentrations on quality of selected dried mango (Mangifera indica L.)

Preference for dried mango is on the increase as it provides a good source of nutrients, whilst evading consumption of fatty in some post-harvest processed fruits. However, data on proximate and chemical compositions of dried mango fruits is lacking. Hence this research was intended to determine effects of sulphur concentration (0, 10, 20, 50, 100, 150, 200, 250 and 300 ppm) on the nutritional value and the proximate composition of six selected mango cultivars (Tommy Atkins, Peach, Saber, Sunshine, Keitt and Vhavenda) grown in South Africa. The study shows that increasing sulphur concentration had a quadratic effect on mango pulp proximate concentration and chemical composition, reaching a maximum at 50 ppm regardless of cultivar. Significant differences (p<0.01) in nutrient content were found in the mango cultivars. Keitt had significantly more protein than other cultivars, whilst Vhavenda had more fibre contents. Significant differences (p<0.01) in secondary metabolites were also found in the mango cultivars with Saber having significantly more polyphenols (0.4 mg of Gallic acid/100 mg) and antioxidants (65.4 μmol/g). Keywords : Mango cultivars, nutritional value, proximate composition, sulphur African Journal of Biotechnology Vol. 12(19), pp. 2678-2684

Growth, Structural and High Pressure Study of GeS&lt;sub&gt;0.25&lt;/sub&gt;Se&lt;sub&gt;0.75&lt;/sub&gt; and GeS&lt;sub&gt;0.75&lt;/sub&gt;Se&lt;sub&gt;0.25&lt;/sub&gt; Single Crystals

The orthorhombic semi-conducting compound GeS0.25Se0.75 and GeS0.75Se0.25 possess interesting electrical properties and can been the subject of numerous investigations. The changes in solids under high pressure can reveal several new features of interatomic forces, which are responsible for their diverse physical properties. Authors have carried out growth of GeS0.25Se0.75 and GeS0.75Se0.25 crystals by Direct Vapor Transport (DVT) technique. For compositional confirmation energy dispersive analysis of X-ray (EDAX) has been used. EDAX results show that the grown crystals are nearly stoichiometrycally perfect. The grown crystals have been characterized by X-ray diffraction technique (using Philips X Pert MPD diffractometer) for structural characterization. These crystals are crystallized in orthorhombic structure. The values of lattice parameters, unit cell volume and X-ray density are calculated and presented. It is observed from lattice parameters, unit cell volume and X-ray density, that as the content of sulfur increases the value of all the lattice parameters decreases. High pressure study is also of great importance to visualize the mechanism governing the structural changes and to reveal solid state properties associated with different structure. For the room temperature measurement of resistance as a function of pressure, up to 7 GPa, the sample was set at the centre of the talc disc on the lower anvil. The pressure was generated by a hydraulic press on the Bridgman type tungsten carbide opposed anvil apparatus with in-situ Bismuth pressure calibration. The resistance was measured in several independent runs on these crystals as a function of pressure and was found to be reproducible. The results of variation of electrical resistance do not show presence of any phase transition up to 7 GPa. We investigate in GeS0.25Se0.75 and GeS0.75Se0.25 single crystals that as sulfur content increases, resistance of this compound increases.

The effect of dopant on structural, thermal and morphological properties of DBSA-doped polypyrrole

Polypyrrole is prepared with different molar ratios of dodecylbenzene sulfonic acid (DBSA) (0.1, 0.2, 0.3 and 0.4) by in situ chemical polymerization method. The reaction temperature was 0–5 °C for 24 h. The FTIR spectrum confirmed the attachment of sulfonyl group in the pyrrole structure. The intensity of polypyrrole increased with increase in sulfur content. SEM graphs revealed the granular morphology of the doped polymer surface. DBSA has had strong effect on morphology with formation of aggregated particles at higher concentrations. Higher concentration of DBSA-doped PPy shows higher thermal stability. The promotion of electron from ground state to excited state of polypyrrole is confirmed by UV spectroscopic studies. Various sizes in particle distribution of DBSA-doped PPy were analyzed by a particle size analyzer. Solubility of polypyrrole was determined at room temperature. The solubility and quantity of polypyrrole increased with higher dopant concentration. Current–voltage (I–V) characteristics were carried out over the temperature range 313–343 K, which was found to be linear. The conductivity of doped-PPy showed high conductivity at low concentration of dopant while, conductivity decreased with increasing concentration of DBSA. The higher doping level of DBSA was confirmed by elemental analysis.

Role of Sulfur on the Transition from Graphite to Cementite Eutectic in Cast Iron

In the current study, an analytic solution is considered to explain the influence of sulfur on the transition from graphite to cementite eutectic in cast iron. The outcome from the current study indicates that this transition can be related to (a) the graphite nucleation potential (directly characterized by the cell count and indirectly by the nucleation coefficients; (b) the eutectic graphite growth rate coefficient; (c) the temperature range between the equilibrium temperature for graphite eutectic and the formation temperature for cementite eutectic; and (d) the liquid volume fraction, after pre-eutectic austenite solidification. In addition, the absolute and the relative chilling tendencies, as well as critical cooling rates including the chill width of the cast iron can be predicted from the current study. The analytic model was experimentally verified for castings with various sulfur contents. It is found that the main role of sulfur on the transition from graphite to cementite eutectic is through its effect on lowering the growth coefficient, and hence, the graphite eutectic growth rate. In addition, it is found that with the increasing sulfur content, the critical cooling rate is significantly reduced, thus increasing the absolute and the relative chilling tendency values, including the chill width.

Structural Modification of Sand Cast Eutectic Al-Si Alloys with Sulfur/Sodium and Its Effect on Mechanical Properties

In the present study, the structural modification of sand cast Al-12wt%Si alloy with sulfur/sodium and its effect on mechanical properties were investigated. Different addition levels of sulfur and sodium were used to modify and produce castings of the same shape and size from the alloy. The results indicated that the addition of sodium or sulfur to eutectic Al-Si alloy can modify the Al-Si eutectic morphology from needle-like eutectic silicon structure to fine-scale eutectic silicon structure with significant improvement in mechanical properties of the alloy. The optimum levels of modification by sodium flux (60% NaF and 40% NaCl) and sulfur were found to be 0.6% - 1.0% and 0.02% - 0.05% of the weight of the alloy respectively. The alloy modified with 0.6% Na flux had the best mechanical properties closely followed by the one modified with 0.02% sulfur. Over modification of the alloy with sodium produced over modification band which consisted of aluminum dendrites and coarse silicon particles in the microstructure of the alloy. Increase in concentration of sulfur decreased the degree of fineness of the eutectic silicon structure with significant decrease in mechanical properties of the alloy and this is suggested to be as a result of the presence of a brittle sulfur compound at the grain interfaces of the alloy.

Proximate, chemical compositions and sulphur concentrations on quality of selected dried mango (Mangifera indica L.)

Preference for dried mango is on the increase as it provides a good source of nutrients, whilst evading consumption of fatty in some post-harvest processed fruits. However, data on proximate and chemical compositions of dried mango fruits is lacking. Hence this research was intended to determine effects of sulphur concentration (0, 10, 20, 50, 100, 150, 200, 250 and 300 ppm) on the nutritional value and the proximate composition of six selected mango cultivars (Tommy Atkins, Peach, Saber, Sunshine, Keitt and Vhavenda) grown in South Africa. The study shows that increasing sulphur concentration had a quadratic effect on mango pulp proximate concentration and chemical composition, reaching a maximum at 50 ppm regardless of cultivar. Significant differences (p<0.01) in nutrient content were found in the mango cultivars. Keitt had significantly more protein than other cultivars, whilst Vhavenda had more fibre contents. Significant differences (p<0.01) in secondary metabolites were also found in the mango cultivars with Saber having significantly more polyphenols (0.4 mg of Gallic acid/100 mg) and antioxidants (65.4 μmol/g). Keywords : Mango cultivars, nutritional value, proximate composition, sulphur African Journal of Biotechnology Vol. 12(19), pp. 2678-2684