Effect Of Sulfur Content Research Articles

Experimental study of high-pressure ultrasound-assisted oxidative desulfurization (UAOD) and sulfone adsorption/desorption using zeolite-13X

The sulfurous compounds in natural gas liquids should be reduced to the extent of satisfying the standard recipes due to corrosion, poisoning of catalysts in downstream processes, reduction in the quality of hydrocarbon products and environmental issues. Ultrasound-assisted oxidative desulfurization is an emerging method for sulfur removal from natural gas liquids. Since natural gas liquids exist in the liquid form of hydrocarbons at high pressures and ambient temperature (25 °C), this work aims to investigate the optimal conditions governing ultrasound-assisted oxidative desulfurization for various sulfurous compounds including mercaptan, sulfide and thiophene at high pressure and finally to appraise the adsorption of oxidized sulfurs and the regeneration of the adsorbent using elution with hot water. So, the effects of sulfur content and ultrasonication time were evaluated at 30 bar. Results showed that as the initial sulfur concentration in normal heptane was increased from 0.00 to 3000 ppmS, the sulfur removal efficiency was enhanced by less than 2 % of 95.9 % and of course, the increased ultrasonication time improved the sulfur removal efficiency. Next, results of the sulfone adsorption using zeolite-13X at 30 bar in continuous mode confirmed that the breakthrough time was reduced from 63 to 12 min as the weight hourly space velocity was increased from 5 to 20 h−1 and pursuantly, the mass transfer zone diminished. Besides, the breakthrough time decreased by 45 - 10 min for increasing the initial sulfur content from 200 to 1000 ppmS. Changing the pressure of the adsorption process from 1 to 30 bar caused the improvement of sulfone adsorption capacity by approximately 3.75 times. In continued, the regeneration of zeolite-13X contaminated with sulfone by flowing hot water was evaluated and the zeolite-13X bed was completely regenerated.

Effect of Sulfur Content on Precipitation Behavior of Dendrite Sulfide Inclusion in Continuous Casted 20CrMnTi Gear Steel

The effect of sulfur content on sulfide inclusion and dendrite MnS in continuous casted 20CrMnTi gear steel is investigated. There are two main types of sulfides in 20CrMnTi steel: pure MnS and TiN–MnS composite inclusions. The number of TiN–MnS is higher than MnS, especially in the edge of the billet. TiN–MnS is smaller both in area and size than pure MnS. The statistical results of dendrite MnS show that the increase of S content decreases the average size of sulfides, whereas raises the number and the maximum size of sulfides. With the S content increasing, the proportion of large‐sized dendrite MnS in steel decreases, but the amount of large‐sized dendrite MnS increases, which results in the increase of number of large‐sized dendrite MnS. The average area of dendrite MnS inclusions first increased and then decreased from the edge to the center of billet, and the maximum area appeared at about 1/2 radius of the billet. Comparison with the microstructure of the two billets, the proportion of ferrite increased with the increase of S content.

Effect of sulfur content on precipitation behaviour of MnS-containing inclusions in X70 pipeline steel

The presence of oxide-MnS complex inclusions is beneficial for the improvement of hydrogen resistance in pipeline steel. The effect of S and Mg contents on the generation mechanism of MnS, MgAl2O4, and MgO inclusions, and the heterogeneous nucleation principle of MnS on the surfaces of MgAl2O4 and MgO were revealed using laboratory experiments, thermodynamic calculations, and density functional theory (DFT) computations. The inclusion characteristics in steel were evaluated by using a Scanning Electron Microscope in combination with an Energy Dispersive Spectrometer (SEM + EDS). It has been found that as the Mg content increased, MgAl2O4 transformed into MgO, which can be well predicted by thermodynamic calculations. It was found that MnS exhibited the ability to nucleate heterogeneously on the surfaces of MgO and MgAl2O4 inclusions. Furthermore, proper S content (approximately 30 ppm) can facilitate the formation of oxide-MnS complex inclusions, excess S content was not desired. The smaller the oxide inclusion, the easier to form wrapped MnS on the oxides. The nucleation ability of MnS and MgAl2O4 was identified by DFT calculations and found that they followed the order of (111)MnS//(111)MgAl2O4>(100)MnS//(100)MgAl2O4>(110)MnS//(110)MgAl2O4. Furthermore, the heterogeneous nucleation ability of MnS and MgO followed in the order of (111)MnS//(111)MgO > (100)MnS//(111)MgO > (100)MnS//(100)MgO. This study provides theoretical evidence supporting the heterogeneous nucleation ability of MnS on the surfaces of MgO and MgAl2O4. Moreover, it helps bridge the disparity between the calculation of MnS and MgO nucleation using the two-dimensional mismatch degree and the experimental findings.

Optimization of eucalyptus cellulose fiber using response surface methodology: Effects of sulfur content and refining time on the mechanical characteristics of paper pulp

The purpose of this study was to examine the delignification of Eucalyptus camaldulensis fibers by the kraft chemical process using sodium hydroxide and sodium sulfide as fillers. To optimize the levels of factors influencing pulp yield and pulp content, a response surface approach with a central composite plane was used. Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were used to characterize the structure and thermal properties of cellulose fiber. Then, a dynamometer, a dechirometer, and an eclatometer adamel were used to evaluate the physico-mechanical properties (breaking length, tear resistance, and resistance to burst) of the paste. The results show that FTIR spectroscopy confirmed the structure of the cellulose fiber; the crystallinity index is 76.35%, the maximum degradation temperature is 368 °C and the kinetic energy of activation (75.45 kJ.mol-1) according to thermogravimetric studies. Subsequently, for the predicted optimal pulping conditions, the concentration of NaOH was 18.8% and 13.40% Na2S at 105 °C for 45 min. Finally, the results obtained for the evaluation of the papermaking properties of fibers during refining showed that the breaking length is 34% (2975 m–1958 m) with a sulfide concentration of 0%–30%, respectively, and that when the refining intensity is increased to 45°SR, the rupture length (5997-4088 m) decreases by approximately 31% under the same conditions. Then, the tear strength is 37.5% (53-33.1), the sulfide concentration is 0%–30%, and the refining intensity is 20°SR; the increase in the latter leads to a reduction in the tear index of approximately 19% (50-40.6) under the same conditions. Finally, the bursting index is 38.5% (18.4-11.3) at identical sulphide concentration and refining intensity, but the increase in the latter leads to a slight decrease in the burst index (37.7-23.6) which is about 37.40%. The results suggest that the valorization of Eucalyptus fibers for the production of well-delignified, high-yield, and resistant pulp is a promising approach. This research qualifies eucalyptus fiber as a potential reinforcement in composite materials.

Synergistic effects of holey nanosheet and sulfur-doping on the photocatalytic activity of carbon nitride towards NO removal

Photocatalysis provides a sustainable way for NOx elimination. However, efficient and safe photocatalytic removal of NOx remain a great challenge due to the limited light-harvesting ability and quick recombination of charge carriers. Herein, holey sulfur-doped g-C3N4 nanosheets (CNN–S) was reported by directly calcining a mixture of hydrolyzed dicyandiamide and thioacetamide. The specific surface area of the pristine g-C3N4 nanosheets (CNN–S0) is 3–4 times higher than bulk g-C3N4 (BCN), and the photocatalytic NO removal rate also increased from 17% (BCN) to 35% (CNN–S0). The effect of sulfur content on the photocatalytic performance was systematic studied, and CNN–S0.5 sample exhibits the highest NO removal rate (53%). The high photoreactivity of S-doped g-C3N4 nanosheets can be attributed to enhanced visible light absorption, increased specific surface area, and effective separation and transfer of photo-generated charges owing to the synergistic effect of the nanosheet structure and sulfur doping. In addition, density functional theory calculations show that the doping of S is also beneficial to the adsorption and activation of the reactants on CN.

Characterization of precipitation, evolution, and growth of MnS inclusions in medium/high manganese steel during solidification process

MnS as a main manganese-containing inclusion in medium/high manganese steel, which can be determined to the mechanical properties of steel. However, the precipitation and evolution mechanism of MnS in medium/high manganese steel is still unclear due to the special solidification properties and element segregation behavior. Hence, the effects of sulfur content, manganese content and cooling rate on the precipitation, evolution, and growth behavior of MnS inclusions in medium/high manganese are various experimentally characterized and thermodynamically elucidated in the present work. The results of 2D and 3D observation indicated that the morphology of MnS in medium manganese steel were transformed from globular and spindle-like (type I MnS) into large-sized rods (type II MnS) and dendritic (type D MnS), when sulfur content was increased from 78 ppm to 1578 ppm. Particularly, the spatial distribution and structure of MnS inclusions are elaborated in detail through X-ray micro-CT observations, which are discussed by defining the quantitative topography parameters and statistical analysis. Based on in situ CSLM observations, MnS precipitation path in high sulfur medium manganese steel was monitored as L → (L + δ + MnS) → (δ + MnS) → (δ + γ + MnS) → (γ + MnS) → (α + γ + MnS) → (α+MnS). Simultaneously, the Scheil-solidification calculations demonstrated that MnS is precipitated at the interdendritic region where the solid-liquid states are coexisted, which is caused by the segregation of sulfur and manganese. Moreover, increasing sulfur content generates the earlier precipitation, and leads to the significant increase in the number and size of MnS inclusions. Besides, the increase of manganese content promotes the transition of MnS from globular to polyhedral shape, which is attributed to the dissociative eutectic reaction of MnS formation preferentially takes place earlier in case of high manganese steel. It is also found that the decreasing of cooling rate and increasing the manganese content tends to increase the number and size of MnS inclusions, which is resulted from the long growth times of high manganese steel induced by large solid-liquid temperature differences. This work provides a systematic understanding of the precipitation and evolution of MnS inclusions in medium/high manganese steel.

Влияние поверхностной ёмкости положительных электродов на длительность циклирования литий-серных аккумуляторов

The effect of sulfur content in positive electrodes (the surface capacity of sulfur electrodes) on the characteristics (such as the depth of sulfur electrochemical reduction, changes in capacitance and Coulomb efficiency during cycle life) of lithium-sulfur cells with electrolytes based on sulfolane was studied. It was shown that the reason for the capacitance decrease of the lithium-sulfur cells at the early stage of its cycle life is the displacement of sulfur of the porous positive electrode from the rear regions into the front ones. It was established that in order to achieve the maximum possible specific energy of the lithium-sulfur batteries with the electrolytes based on sulfolane, the surface capacitance of the positive electrodes should be in the range of 2-3 mA·h/cm2.

Performance and Mechanisms of Sulfidated Nanoscale Zero-Valent Iron Materials for Toxic TCE Removal from the Groundwater.

Trichloroethylene (TCE) is one of the most widely distributed pollutants in groundwater and poses serious risks to the environment and human health. In this study, sulfidated nanoscale zero-valent iron (S-nZVI) materials with different Fe/S molar ratios were synthesized by one-step methods. These materials degraded TCE in groundwater and followed a pathway that did not involve the production of toxic byproducts such as dichloroethenes (DCEs) and vinyl chloride (VC). The effects of sulfur content on TCE dechlorination by S-nZVI were thoroughly investigated in terms of TCE-removal efficiency, H2 evolution, and reaction rate. X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) characterizations confirmed Fe(0) levels in S-nZVI were larger than for zero-valent iron (nZVI). An Fe/S molar ratio of 10 provided the highest TCE-removal efficiencies. Compared with nZVI, the 24-h TCE removal efficiencies of S-nZVI (Fe/S = 10) increased from 30.2% to 92.6%, and the Fe(0) consumed during a side-reaction of H2 evolution dropped from 77.0% to 12.8%. This indicated the incorporation of sulfur effectively inhibited H2 evolution and allowed more Fe(0) to react with TCE. Moreover, the pseudo-first-order kinetic rate constants of S-nZVI materials increased by up to 485% compared to nZVI. In addition, a TCE degradation was proposed based on the variation of detected degradation products. Noting that acetylene, ethylene, and ethane were detected rather than DCEs and VC confirmed that TCE degradation followed β-elimination with acetylene as the intermediate. These results demonstrated that sulfide modification significantly enhanced nZVI performance for TCE degradation, minimized toxic-byproduct formation, and mitigated health risks. This work provides some insight into the remediation of chlorinated-organic-compound-contaminated groundwater and protection from secondary pollution during remediation by adjusting the degradation pathway.

Effect of Sulfur Content on Copper Recovery in the Reduction Smelting Process

This work discussed the advantages of reducing copper in molten copper slag with low S content. FactSage calculated the distribution of copper at equilibrium under different sulfur contents. The effect of sulfur content on copper recovery under different oxygen partial pressures in 1400 °C was pointed out. The effect of sulfur content on copper recovery in the actual reduction process was explored through experimental research. Under the condition of low sulfur, the recovery ratio of copper and the stability of the experiment have an ideal result in fixed C/O in the experiment.

Mechanical behavior, failure pattern and damage evolution of fiber-reinforced cemented sulfur tailings backfill under uniaxial loading

In order to explore the mechanical properties of cemented sulfur tailings backfill (CSTB), uniaxial compression tests of cemented sulfur tailings backfill (CSTB) were carried out in the laboratory, and the effects of sulfur content and polypropylene fiber on the mechanical properties, failure pattern and damage evolution of the CSTB were systematically studied. Moreover, fiber factor γ is introduced to measure the impact of polypropylene fiber on mechanical behavior of CSTB. The peak stress, residual stress and elastic modulus of the CSTB all increase initially and decrease afterwards with the fiber factor γ increasing. When the fiber content is 0%∼0.6%, the three factors show exponential and quadratic function with the fiber factor γ increasing. The total strain energy, elastic strain energy and dissipative strain energy of CSTB at the peak stress point all increase first and then decrease with the fiber factor γ increasing, and all reach the maximum value when the fiber content is 0.6%. Under uniaxial loading, the elastic strain energy of CSTB presents a change characteristic of “gentle - rapid increase - slow increase - rapid decline” with the increasing axial strain, while the dissipative strain energy presents a change characteristic of “gentle - steady increase - rapid increase”. In addition, each strain energy (dissipative strain energy, total strain energy and total strain energy) of CSTB at the peak stress point all increase initially and decrease afterwards with the fiber factor γ increasing. Then, the piecewise damage constitutive model taking fiber factor γ into consideration was established. Under uniaxial loading, the damage evolution of backfill can be divided into four stages: no damage stage, slow growth stage, acceleration stage and damage failure stage. It shows that polypropylene fiber can effectively inhibit the damage and failure of CSTB, thus improving the bearing capacity and anti-deformation and failure ability of CSTB. The CSTB without fiber shows obvious shear failure characteristics, and there are obvious large-scale “Y-shaped” and “linear” failure cracks on the sample surface. There is not only one or two major large-scale cracks in the failure of CSTB containing fiber, but also the range of fracture surface is very limited, indicating that adding fiber can effectively inhibit the crack propagation of CSTB during failure and improve the overall anti-crack ability of CSTB.

Effect of sulfur content on improving physical properties of new sprayed Cu2MgSnS4 thin films compound for optoelectronic applications

Effect of sulfur content on improving physical properties of new sprayed Cu2MgSnS4 thin films compound for optoelectronic applications

Effect of Sulfur Content on the Inclusion and Mechanical Properties in Ce-Mg Treated Resulfurized SCr420H Steel

To clarify the effect of sulfur on inclusions and mechanical properties of Ce-Mg treated resulfurized SCr420H steel. Laboratory experiments were conducted to prepare steels with sulfur contents as 0.01%, 0.06%, and 0.132%. Inclusion evolution in liquid steel, MnS precipitation during solidification, and tensile test results of steel after quenching and tempering were investigated. The results showed that due to the limitation of mass transfer in molten steel, composite inclusion that Ce-O-S wrapped by Ce-Ca-Mg-Al-Si-O, which was named transition state inclusions, can form quickly after adding Ce-Mg lump to the molten steel. As the homogenization of molten steel, the difference of sulfur content in steel can lead to the transition state inclusions transformed into different inclusions. With the increase of sulfur content, the quantity of MnS increased significantly, and the morphology of MnS transformed from “stick” to “dendritic + fishbone”, and then to “fishbone”. Tensile test results and fracture analysis indicate that the decline of inclusion spacing as the increase of sulfur content leads to a shorter physical path of crack propagation in steel. Therefore, the increase of sulfur content can bring about a decrease in the strength and plasticity of the steel. From the perspective of inclusion control, making the MnS inclusion precipitate more dispersive and increasing the distance between inclusions can be considered as a method for preventing the decline of mechanical properties in steel with high sulfur content.

The Effect of Sulphur Content on the Microstructure of Vermicular Graphite Cast Iron

The Effect of Sulphur Content on the Microstructure of Vermicular Graphite Cast Iron

Dye-sensitized solar cell using nickel sulfide-reduced graphene oxide counter electrode: Effect of sulphur content

The influence on sulphur content in term of thiourea (TU) concentration on the properties of nickel sulphide (NiS)-reduced graphene oxide (rGO) has been reported in this paper. The effect of sulphur content on the performance of dye-sensitized solar cell (DSSC) using NiS-rGO counter electrode (CE) has also been investigated. The source of sulphur is TU. The sample has been prepared via modified Hummers’s method assisted with spin coating technique. The cell using NiS-rGO CE prepared with 1.20 M TU yielded the highest power conversion efficiency (η) of 1.42%. This is due to this cell has the lowest series resistance (Rb) and charge transfer resistance at the interface of NiS-rGO CE/electrolyte (Rct) with the value of 0.44 and 4.09 Ω, respectively. It is also due to the sample with 1.20 M TU owns the highest reduction current (J). The finding of this work reveals that NiS-rGO is able to substitute platinum as CE for DSSC.

Effect of Sulfur Content on Evolution of Nonmetallic Inclusions in Low Sulfur Al‐Killed Steels during Heat Treatment

Herein, the effect of total sulfur (T.S) on the transformation of inclusions in Al‐killed steels is investigated through lab experiments and kinetic calculations. During the heating process, CaS content in inclusions obviously rises up, while the CaO content reduces. The CaO content in inclusions with 11 ppm S in steel is higher than 15%, while it is less 5% for the steel with 25 ppm S. The initial CaO–Al2O3 inclusions before heating change to CaS–MgO–Al2O3 at 1200 °C. The higher T.S promotes the transformation of inclusions in low sulfur Al‐killed steels, leading to the higher CaS content in inclusions after the heat treatment. A kinetic model is developed to predict the transformation of inclusions in low sulfur Al‐killed steels during the heat treatment. The transformation fraction of inclusions decreases with the larger size of inclusions and increases with the higher T.S content in steel at the heating temperature.

Effect of sulfur content in the crude oil to the corrosion behavior of internal surface of API 5L X65 petroleum pipeline steel

This work discussed the corrosion behavior of the internal surface of pipeline steel caused by the composition of petroleum products, particularly crude oil. Internal and external pipeline corrosion is the notable cause of pipeline failure in Malaysia’s oil and gas industry. However, internal corrosion is preferred to be concerned in this work because it involved one of the major corrosive media in the crude oil, such as sulfur content. This project aim is to find the sulfur concentration in the crude oil using Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The corrosion rate, corrosion current and corrosion potential of the API 5L X65 grade carbon steel pipeline in different simulated H2SO4 solution concentrations were carried out using the Tafel extrapolation technique. The corrosion properties of the samples were morphologically measured by means of optical microscope, scanning electron microscope and energy dispersive X-ray analyses. The results showed that the corrosion rate of the pipeline steel significantly increased with the increasing H2SO4 concentrations. The corrosion products formed on the pipeline steel surfaces were mainly composed of iron sulfate, iron sulfide and iron oxide. These findings are crucial to understanding the corrosion behavior caused by the crude oil and should be further investigate with the other possible influence factors such as temperature and petroleum’s flowing velocity.

Effect of Sulfur on Hot Compression Properties of C71500 Cupronickel Alloy

The influence of sulfur on the hot compression properties of C71500 cupronickel alloy and the mechanism of thermo mechanical effect are studied for the first time. The composition of sulfide inclusions and its damage mechanism to properties were also studied. The effect of sulfur content on the dynamic recrystallization activation energy and the properties of the alloy was deduced and explained systematically. The relationship between the dynamic recrystallization activation energy and sulfur content was obtained, and a energy dissipation model was established based on the dynamic material model. The Prasad’s instability criterion was used to predict the unstable region in the processing chart. The effect of sulfur on the processing parameters selection was compared under different strain conditions, which could provide the ideal processing technology for the thermal deformation of C71500 alloy with various sulfur content.

Toward morphology development and impact strength of Co-continuous supertough dynamically vulcanized rubber toughened PLA blends: Effect of sulfur content

In this study, supertough dynamically vulcanized blends (DV) of polylactide (PLA) and acrylonitrile butadiene rubber (NBR) are prepared. Effects of sulfur content on the compatibility, interfacial adhesion, morphology and impact resistance are investigated. NBR presents in spherical droplets dispersed in the PLA phase in absence of sulfur. With addition of sulfur, however, NBR tends to present in a continuous phase formed by numerous microfibril-like elongated vulcanized rubber, whereas the DV with 3 phr sulfur demonstrates a more uniform co-continuous structure. Correspondingly, the DV exhibits a sharp brittle-ductile transition occurs as the sulfur content increases from 1.5 to 2.5 phr, and the DV with 3 phr achieves an impact strength of almost 30 times that of neat PLA. This work aims to illustrate the development of network-like dispersion of vulcanized rubber in PLA-based DVs, and the findings provide a useful guideline in future exploration of PLA-based DVs.

Poly(butylene disulfide) and poly(butylene tetrasulfide): Synthesis, cure and investigation of polymerization yield and effect of sulfur content on mechanical and thermophysical properties

In this work, two polysulfide polymers were synthesized by use of 1,4-dichlorobutane and aqueous sodium disulfide or sodium tetrasulfide. The polymers were cured at 85 °C. The structural characteristics of non-cured and cured samples were identified by Raman and FT-IR spectroscopy. The morphological and the thermophysical properties of all samples were investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Also, the mechanical properties and hardness of all samples were investigated by tensile test and Shore A. Moreover, the effects of temperature and ethanol on polymerization were investigated. Aqueous monomers were characterized by UV-VIS-NIR spectroscopy. The molecular weight of the synthesized samples was determined by 1H NMR spectroscopy. The results showed that, before curing, poly(butylene tetrasulfide) (PBTS) due to amorphous structure does not have a melting peak and both polymers have a very low glass transition temperature. Without ethanol, no polymerization reaction takes place. Before curing, poly(butylene disulfide) (PBDS) is brittle and PBTS has an elastomeric behavior, but after curing PBDS also behaves as elastomer. The curing times of the two polymers are close to each other, but their mechanical properties and hardness are different.

Swirling Flame Combustion of Heavy Fuel Oil: Effect of Fuel Sulfur Content

Abstract In the present work, an experimental investigation on the effect of sulfur content in heavy fuel oil (HFO) on the gaseous emissions under swirling flame conditions was carried out. The sulfur content in HFO was varied by blending with ultra-low sulfur diesel and four fuel samples containing 3.15, 2.80, 1.97, and 0.52% sulfur (by mass) were prepared. Pure asphaltenes were added to the blends to ensure that the asphaltene content in the fuel remained the same. The fuels were then fired in a high-swirl stabilized, turbulent spray flame. The combustion performance of the fuels was evaluated by measuring flame temperature distribution, gaseous emissions (SOx, NOx, CO, CO2, and flue gas pH), and particulate matter (PM) emissions (morphology, composition, and pH). The results showed a significant reduction in the SO2 emissions and acidity of the flue gas when the sulfur content in the fuel was reduced, as expected. The reduction was more than would be expected based on sulfur content, however. For example, the flue gas SO2 concentration reduced from 620 ppm to 48 ppm when the sulfur content in the fuel was reduced from 3.15 to 0.52% (by mass). Sulfur balance calculations indicate that nearly 97.5% of the sulfur in the fuel translates into gaseous emissions and the remaining 2.5% appears in PM emissions. Ninety-five percent of the gaseous sulfur emissions are SO2, whereas the rest appears as SO3. Varying the sulfur content in the fuel did not have a major impact on the flame temperature distribution or NOx emissions. The morphologies and the size distribution of the PM also did not change significantly with the sulfur content as the asphaltenes content of the fuels remained the same.