Sulfide Capacity Research Articles

Thermodynamic Properties of Sulfur in the CaO–AlO1.5–CeO1.5 Slag System at 1873 K

Elements with a high affinity for O and S in molten steel are desirable as deoxidizing and desulfurizing agents in the steel refining process, and Ce has attracted attention. In this study, the thermodynamic properties of sulfur in a CaO–AlO1.5–CeO1.5 slag system at 1873 K are investigated. A chemical equilibrium method using Cu is employed for these measurements. Sulfide capacities are determined in the CaO–AlO1.5–CeO1.5 system to show desulfurization ability; the precipitated phases are identified when large amounts of sulfur are added to the CaO–AlO1.5–CeO1.5 system; the solubility of CaS in the CaO–AlO1.5–CeO1.5 system is determined. It is suggested that the slag of this system can improve sulfur distribution while reducing the Al concentration in the steel.

Growth boundary of Fusarium graminearum spores as a function of temperature, pH, and H2S based on neural network

Fusarium graminearum (F. graminearum) poses a substantial threat to global food security, with its impact closely linked to environmental conditions. This study aims to anticipate F. graminearum spore growth across diverse environments and assess alterations in the fungistatic capacity of hydrogen sulfide (H2S) gas in response to environmental variations. The experimental data, namely spore germination ratios, are monitored and recorded at hourly intervals across 100 permutations comprising four distinct temperature levels, five varying pH values, and five diverse concentrations of H2S. The investigation integrates three environmental factors as input variables, utilizing a feedforward neural network to establish growth boundaries based on spore germination ratios. The accuracy of models at various stages–training, validation, and testing–is evaluated using a confusion matrix. Logistic regression models are employed for effectiveness comparison with neural networks. Results indicate that neural networks successfully predict F. graminearum spore germination events. Notably, H2S does not influence the temperature preferences of spores. Temperature has a more substantial impact on the fungistatic ability of H2S compared to pH. The study reveals the adaptability of F. graminearum spores to adverse conditions over time. This research delves into temperature, pH, and H2S synergistic effects on spore germination, contributing to predictive models for F. graminearum and enhancing our understanding of how environmental factors regulate its growth.

Thermal property characterization and modeling of SMAW electrode coating flux using ANN and regression analysis

The design and development of SMAW electrode coating fluxes, along with their thermal property characterization, are discussed. Using an extreme vertices design approach, 27 flux mixture combinations have been prepared. The TGA-DSC and hot disk analysis are done to quantify the thermal response of the fluxes. Results show that increase in CaF2 and SiO2 reduces weight loss. Increase in CaO increases weight loss, whereas increase in BaO shows minimal effect on weight loss. Enthalpy change of flux was found to influence mainly with CaF2 and CaO. Thermally stable flux has lower volatile compounds such as crystallization water and moisture, which helps to minimize gaseous entrapment in weld pool. An increase in CaF2 shows slight decreases and then increase in thermal diffusivity. The increase in thermal diffusivity leads to instant heat flow in the coating. Regression analysis is done, and the effect of individual and interaction of flux constituents on thermal properties is discussed. The artificial neural network is employed for predictive modeling in the domain of the mixture design approach, its prediction accuracy is compared with regression analysis. Water vapor solubility of slag was estimated between 3.169 and 3.947 and sulfide capacity of slag was − 2.479 to −1.892.

Synthesis of Flower-like Crystal Nickel–Cobalt Sulfide and Its Supercapacitor Performance

In order to improve the pseudocapacitance performance of metal sulfide electrode materials and obtain supercapacitor energy storage devices with excellent electrochemical reversibility and long-term cycle stability, the synthesis of flower-shaped crystal nickel–cobalt sulfide and its supercapacitor performance were studied. NiCo2S4 flower-shaped crystal nickel–cobalt sulfide was prepared by the hydrothermal method with nickel foam as the raw material, and electrode materials were added to prepare supercapacitor electrodes for testing of the supercapacitor performance. The physical properties of flower-shaped crystal nickel–cobalt sulfide were tested by a scanning electron microscope and transmission electron microscope, and the voltammetric cycle and constant current charge and discharge of supercapacitor electrodes prepared from this sulfide were analyzed through experiments. The experimental results showed that the flower crystal microstructure had a positive effect on the electrochemical properties. The capacitance value was always high at different current densities, and the capacity was as high as 3867.8 A/g at pH 12. After 2000 voltage–charge–discharge cycle tests, the petal-like sulfide capacity still had a retention rate of 90.57, the flower crystal nickel–cobalt sulfide still showed an excellent supercapacitor performance and the specific capacity was still high, which demonstrates that this sulfide has excellent cyclic stability and durability in electrochemical applications.

Hydrochloric acid induced microstructural reconfiguration from bulk α-NiS microspheres to porous/hollow NiSx microspheres for high-performance hybrid supercapacitor

Nickel sulfide is well known as a promising energy storage/conversion material considering its high redox activity, high theoretical capacity, easy preparation, and rich phase structures. Unfortunately, nickel sulfide prepared by conventional methods usually exhibits a bulk structure, which significantly limited its charge storage. To overcome this obstacle, we developed a facile hydrochloric acid-induced structure reconstruction strategy to fabricate porous and hollow structured nickel sulfide via a one-step hydrothermal process. We found that nickel sulfide undergoes de-nickelization in the presence of 3 M hydrochloric acid, resulting in the transformation from bulk structure to porous/hollow structures, accompanied by a transition from nickel-rich phase (α-NiS) to nickel-deficient phase (Ni3S4 or NiS2). The electrochemical results demonstrated the obviously improved specific capacity of nickel sulfide after structure reconstruction, among which the porous NS-HCl-1 h (α-NiS/Ni3S4) microspheres delivers the highest specific capacity (204.4 mAh g-1 at 1 A g-1) and show a rate performance about 50.0% from 1 to 20 A g-1. The assembled NS-HCl-1 h//rGO supercapacitor delivers a maximum energy density of 47.1 Wh kg-1 at a power density of 803.6 W kg-1, and maintain a capacity retention rate about 88.6% after 10,000 cycles. This work provides a novel method and contributes new insight for the structural reconstruction of transition metal sulfides (TMSs).

Study on the Cleanliness of SWRS82B Hard Wire Steel Refined by Fluorine‐Free Slag with Medium and High Basicity

In order to apply and develop fluorine‐free slag in steelmaking, it is of great significance to study the effect of composition for fluorine‐free refining slag on the cleanliness of molten steel which affects its performance directly. The effect of composition of fluorine‐free refining slag with medium and high basicity on the contents of impurity elements for sulfur and oxygen, and characteristics of inclusions in SWRS82B hard wire steel, are investigated systematically. Sulfide capacity of refining slag is estimated based on the Royal Swedish Institute of Technology model. Dissolved oxygen content in molten steel equilibrated by refining slag is calculated based on Factsage software and classical thermodynamics. The calculated results are in good agreement with experimental results. The plasticity of inclusions at high temperature and low temperature is analyzed by phase diagram and Young's modulus calculation. The best cleanliness and inclusions of SWRS82B steel are obtained with slag composition of 53%CaO–19%SiO2–19%Al2O3–7%MgO, which has good melting characteristics. The impurity elements sulfur and oxygen in steel can be controlled for 26 and 19 ppm, respectively, and the average size of inclusions is 2.84 μm.

Desulfurization Behavior of FeNi-Based Expansion Alloy Melt Using CaO-SiO2-MgO-Al2O3-CaF2 Slag

The effects of slag components on the sulfur distribution ratio {(wt.%S)/[wt.%S]} were analyzed using thermodynamic calculations. On this basis, the effects of the slag with different binary basicities (wt.% CaO/wt.% SiO2 = 3.0, 5.0, 7.0, 9.0 and 11.0) and Al2O3 contents (wt.% Al2O3 = 12, 16, 20 and 24) on the desulfurization behavior were investigated. The results show that the binary basicity and Al2O3 content were the main factors that affected the desulfurization. And an increase in the binary basicity and a decrease in the content of Al2O3, increase the sulfide capacity of the slag. In the early stage of the smelting process, the desulfurization process was limited due to the high content of oxides, such as FeO and MnO in the slag, and the sulfur content in the alloy melt reached 35 ppm. After the final deoxidation of the Si-Ca alloy, the desulfurization rate was significantly increased, and the maximum desulfurization rate reached 44.12%. During the ladle standing, the sulfur content in the alloy melt changed little because of the limitation of kinetics. The rate-limiting step of the desulfurization process was the diffusion of sulfur in the alloy melt.

RGO and CNTs synergistically modified mixed-phase nickel sulfide nanohybrids with abundant redox-active sites for high-performance hybrid supercapacitors

Hybrid supercapacitors (HSCs) integrating high energy density and power density have great prospects for applications in new high-performance energy storage and conversion devices. Herein, a novel reduced graphene oxide (RGO) and carbon nanotubes (CNTs) synergistically modified mixed-phase nickel sulfide (NiS/NiS2) nanohybrids (NSRCs) were successfully designed and synthesized by a facile one-step solvothermal method. Benefiting from the high conductivity and high specific surface area of carbon materials and the high specific capacity of nickel sulfide, as well as the stable nanostructures constructed by the synergistic effect of multiple components, the synthesized novel NSRCs nanohybrids exhibit impressive electrochemical performances, such as high specific capacity of 178.2 mAh g−1 (1604.1 F g−1) at 0.6 A g−1, excellent rate capability (57.3 % at 20 A g−1). Furthermore, the assembled hybrid supercapacitors (NSRC-24//AC HSC) with optimal NSRC-24 electrode and activated carbon (AC) electrode imparted a high energy density of 44.2 Wh kg−1 at a power density of 359.2 W kg−1 and excellent cycling stability (98.1 % capacity retention after 12,000 cycles at 5 A g−1). Thus, the synthesized novel NSRCs nanohybrids are highly promising candidates as advanced electrode materials for aqueous high-performance energy storage devices.

Research Progress of Desulfurization Refining Slag: A Review

The development of refining slag is the core of the ladle furnace (LF) refining processes and is essential for fast and effective desulfurization refining. Desulfurization reactions are mainly determined by slag–steel interactions, which are closely related to the physicochemical properties of slags. This study reviews the research progress of desulfurization refining slag for the LF process. First, the chemical composition of the refining slag is described, and then three theories of desulfurization and the concepts of sulfide capacity and sulfur partition ratio are introduced. Second, the effects of operating parameters and slag components on desulfurization are examined. Furthermore, the microscopic analysis of the desulfurization process is performed. The prediction models of slag properties related to desulfurization are summarized. Finally, a research direction for LF desulfurization refining is proposed. The question of how to ensure the uniformity of desulfurization remains open. The industrialization of the new refining slag developed by replacing CaO with BaO or Li2O and replacing CaF2 with B2O3 should be accelerated to solve the CaF2 slag volatilization problem. One of the most pressing issues that must be addressed is improving the accuracy of the existing slag performance forecast model.

Evaluation of commercial moving bed media and sugarcane bagasse as packing material in biotrickling filter for hydrogen sulfide removal

This study compared two biotrickling filter packing materials for hydrogen sulfide removal. Inlet H2S concentrations and empty-bed retention time were tested on the two biotrickling filters. First reactor (BT1) had immobilized sulfur-oxidizing bacteria on commercial moving-bed media, whereas second reactor (BT2) had sulfur-oxidizing bacteria on sugarcane bagasse. The study found that BT1 performed best at 120 s empty-bed retention time, 422.39 g/m3·h hydrogen sulfide loading rate, resulted in 416 g/m3·h hydrogen sulfide elimination capacity. In contrast, BT2 performed best at 180 s empty-bed retention time, 278.77 g/m3·h hydrogen sulfide loading rate, and 273 g/m3·h elimination capacity was achieved. High-throughput sequencing showed Acidithobacillus spp. dominated the sulfur-oxidizing bacteria consortium. Sugarcane bagasse may receive less hydrogen sulfide loading than moving bed medium under optimal conditions, but its low cost and reasonable removal capacity of hydrogen sulfide -containing industrial gases in a biotrickling filter system make it an excellent alternative packing material.

Lithium Sulfide –Carbon Composite Use as Positive Electrode in Post Lithium Ion Batteries Technology

Li‐ion batteries (LIBs) are the powerhouse for the electronic devices in this modern mobile society, and enabler of the current communication revolution. Consumers demands advanced electronics and sustainable industries in general. To satisfy these demands, the new generation of rechargeable batteries need to provide much higher energy and power density than the actual technology. Commercial LIBs consist of lithium cobalt oxide as positive electrodes and graphite as a negative electrode, this system has energy density values ca. 250 WhL-1.Lithium-sulfur is commonly considered as one of the most promising chemistries for improve traditional lithium-ion batteries in weight sensitive applications due to high theoretical capacity of lithium sulfide (Li2S) and high gravimetric energy density of such cells. Li2S provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g−1). This positive electrode material can be coupled with lithium-free negative electrode to develop high-energy-density batteries; this can improve the safety of the devices. Li2S is significantly more thermally stable, and offer greater mechanical stability as no further volumetric expansion occurs upon cycling.Li2S particles must be handled only in inert atmospheres (making production of high-performance cathode materials, on a commercial scale, quite difficult) and suffer from rapid degradation in cells during cycling. There are still challenges with it (e.g., low conductivity, high over potential and irreversible polysulfide diffusion), which have prevented the S utilization and stability. The dissolved polysulfides deposit on the surface of both electrodes resulting in a rapid impedance growth, loss in active material and ultimately battery failure.The complex synthesis method of Li2S–carbon composites restrains the large-scale productivity. We propose an easy and time saving method to synthesize a Li2S based nanocomposite cathode material by wet milling.This work may shed fresh insight into bridging the huge gap between high energy and safety of rechargeable cells for feasible applications. Figure 1

A Computational Fluid Dynamics‐Thermodynamics Coupled Approach to Simulate Desulfurization in Ladle Furnace Based on Interface Equilibrium Assumption

This study proposes a coupled computational fluid dynamics and thermodynamics model based on the assumption of interface equilibrium at the steel–slag interface to simulate the desulfurization process in a ladle furnace. The species transport equation is solved to analyze the kinetic behavior and chemical content variation in the melt. The sulfur distribution ratio is calculated based on the slag sulfide capacity and oxygen activity. Subsequently, the solutions are coupled by introducing the species transfer and source terms generated by comparing the initial and predicted thermodynamic equilibrium states at the steel–slag interface cell. The model is validated by experimentally comparing the sulfur content. Furthermore, the model is applied under different kinetics and thermodynamics conditions. With an increase in the gas flow rate, the in‐phase effective diffusion coefficient increases, but the number of interface cells involved in the sulfur transfer process decreases. The complex relationship between the desulfurization process and the gas flow rate results from the mutual antagonism between these two factors. Moreover, the study findings demonstrate that a higher slag basicity enhances the calculated sulfur distribution ratio and final desulfurization ratio.

Sulfur oxidation state and solubility in silicate melts

We have determined the solubility of sulfur (S) as sulfide (S2–) for 13 different natural melt compositions at temperatures of 1473–1773 K under controlled conditions of oxygen and sulfur fugacities (fO2 and fS2, respectively). The S and major element contents of the quenched glasses were determined by electron microprobe. The sulfide capacity parameter (CS2–) was used to express S2– solubility as a function of the oxygen and sulfur fugacities according to the equation: log C_{{S^{2 - } }} = log S_{melt} left( {wt% } right) + 0.5log left( {frac{{fO_{2} }}{{fS_{2} }}} right). Sulfide capacities of silicate melts were found to increase with temperature and the FeO content of the melt. We combined our sulfide data at 1473–1773 K with (O’Neill and Mavrogenes, J Petrol 43:1049–1087, 2002) results at 1673 K, and obtained by stepwise linear regression the following equation for sulfide capacity log C_{{S^{2 - } }} = 0.225 + left( {25237X_{FeO} + 5214X_{CaO} + 12705X_{MnO} + 19829X_{{K_{2} O}} - 1109X_{{Si_{0.5} O}} - 8879} right)/T{ }. XMO is the mole fraction of the oxide of M on a single-oxygen basis, and T is in Kelvin. The sulfide capacity equation was combined with sulfate capacity (CS6+) data for similar compositions and at the same temperatures (Boulliung and Wood, Geochim Cosmochim Acta 336:150–164, 2022), to estimate the S redox state (S6+/S2– ratio) as a function of melt composition, temperature and oxygen fugacity. Results obtained are in good agreement with earlier measurements of S6+/S2– for basaltic and andesitic compositions. We observe a significant increase, however, relative to FMQ of the oxygen fugacity of the S2– to S6+ transition as temperature is lowered from 1773 to 1473 K. We used our results to simulate sulfur-degassing paths for basaltic compositions under various redox conditions (FMQ –2 log fO2 units to FMQ + 2). The calculations indicate that, given an initial concentration of 0.12 wt% S in an ascending melt at 250 MPa, most of the S (> 80%) will be degassed before the magma reaches 100 MPa pressure.

A self-supporting Cu2S/CP lithium-ion battery anode

Lithium-ion (Li-ion) batteries have been widely used in portable electronic devices and new energy vehicles in recent years. Although commercial graphite anode has good safety and low cost, its low theoretical capacity cannot better meet the demand for higher-capacity of power batteries. As an excellent electrode material, copper sulfide (Cu2S) has the advantages of high capacity and stability. Herein, Cu2S deposited on carbon paper (Cu2S@CP) was prepared by simple copper electrodeposition on carbon paper and sulphidation, which can be used to the anode of Li-ion batteries directly. Based on the three-dimensional structure of carbon paper and the high capacity of copper sulfide, the composite anode shows good lithium storage performance, which provides a new possibility for commercial power lithium-ion battery anode materials.

Sulfide Immobilization: Investigating the Impact of a Protective Sulfide-Bearing Layer Formed by Siderite (FeCO3)

Sulfate-rich wastewater poses ecological hazards to freshwater ecosystems, and sulfate is highly regulated in many Minnesota lakes. Biological sulfate reduction results in the reduction of sulfate to sulfide, and this process is used to remediate acid mine drainage. Theoretically, the aqueous sulfide can be immobilized into a solid-phase material and removed from the aqueous system. This study focuses on sulfide immobilization using iron-bearing waste minerals. Specifically, the extent of reaction of siderite (FeCO3), an abundant ferrous mineral in some mining wastes, with sulfide was studied. Mildly acidic batch reactors containing powdered siderite were consecutively injected with a sodium sulfide solution. Solid reaction products were identified and characterized using powder X-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Mackinawite (FeS) appeared to be the most abundant product, with greigite (Fe3S4) also detected. Results reveal that the immobilization capacity of sulfide by siderite is limited by the concentration of the Fe2+(aq) presented in the system immediately before the initial sulfide exposure as the Fe2+(aq) levels are not replenished after sulfidation. These results improve our understanding of the sulfidation of siderite and provide insight to improve the viability of using siderite-containing mining waste rock in a sulfate remediation technology.

Evaluation of the sulphide capacity of Na2O-containing silicate slags using a structural model

ABSTRACT This article suggests that the sulphide capacity may be a unique property of slag that can be calculated at a given temperature and composition, even for CaO- or Na2O-containing slags where the amount of dissolved sulphides is significant. A structural model that incorporates sulphide ions (S2−) in the silicate network is used to calculate the sulphide capacity of SiO2-Na2O binary and SiO2-Na2O-MO (M = Ca, Mg, Mn, Fe) ternary systems. This structural model considers the effect of substituting one metal oxide for another in ternary systems and uses only the data for the binary subsystems without any ternary adjustable parameter.

Sulfide Capacity and Activity of Iron Oxide in CaO–SiO<sub>2</sub>–FeO Ternary System at 1573 K

The knowledge of sulfide capacities of FeO-containing slags is necessary for better understanding the resulfurization reaction in hot metal pre-treatments. In this study, copper-iron-sulfur liquid alloy was equilibrated with CaO–SiO2–FeO ternary slag to measure sulfide capacities and FeO activities simultaneously at temperature below the melting point of pure iron. The experimental result that the sulfide capacity increased with increasing FeO content could be explained by the fact that FeO was a basic oxide, and the sulfide capacity of the CaO–SiO2–FeO ternary system was significantly larger than those of the CaO–SiO2–MgO, CaO–SiO2–AlO1.5 and CaO–SiO2–CaF2 ternary systems. Although the FeO activity and oxygen potential were raised by the FeO addition, the calculated value for sulfur distribution ratio between CaO–SiO2–FeO slag and hot metal increased with an increase in FeO content.

Response of sulfur-metabolizing biofilm to external sulfide in element sulfur-based denitrification packed-bed reactor

Dosing sulfide into the sulfur-packed-bed (S0PB) has great potential to enhance the denitrification efficiency by providing compensatory electron donors, however, the response of sulfur-metabolizing biofilm to various sulfide dosages has never been investigated. In this study, the S0PB reactor was carried out with increasing sulfide dosages by 3.6 kg/m3/d, presenting a decreasing effluent nitrate from 14.2 to 2.7 mg N/L with accelerated denitrification efficiency (k: 0.04 to 0.27). However, 6.5 mg N/L of nitrite accumulated when the sulfide dosage exceeded 0.9 kg/m3/d (optimum value). The increasing electron export contribution of sulfide a maximum of 85.5% illustrated its competition with the in-situ sulfur. Meanwhile, over-dosing sulfide caused serious biofilm expulsion with significant decreases in the total biomass, live cell population, and ATP by 90.2%, 86.7%, and 54.8%, respectively. This study verified the capacity of dosing sulfide to improve the denitrification efficiency in S0PB but alerted the negative effect of exceeded dosing.

Machine learning assisted identification of grey-box hot metal desulfurization model

ABSTRACT Hot metal desulfurization operates as an extraction process in steel production after the blast furnace. Mathematical modeling of the process provides the basis for control and optimization solutions. Owing to complex dynamics, an exhaustive physico-chemical description of the process is computationally infeasible. Thus, a model with a gray–box structure is considered. In the model, a neural network model for sulfide capacity of the slag is implemented in series with the reaction model. The network is trained using an independent data set. The parameters for the reaction model are identified using genetic algorithm with real-encoded population and hybrid selection and recombination operators. The gray-box model parameter distributions are estimated using Metropolis Hastings Algorithm. This study suggests that a sufficiently low mean absolute error can be achieved for the end sulfur content. The relative contribution of the permanent contact reaction to overall reaction rate under industrial conditions remains uncertain.

Viscosity and desulphurisation behaviour of CaO–SiO2–MgO–Al2O3–BaO–MnO slag

ABSTRACT The influence of BaO on the structure, viscosity and sulfide capacity at 1500°C of CaO-SiO2-MgO-Al2O3-BaO-MnO slag was investigated comprehensively. The activity of O2− and activity coefficient of S2− were discussed, and the sulfur distribution ratio was deduced and analyzed from sulfide capacity. The results revealed that the viscosity increased slightly owing to an increase of BaO content, and the complexity of [SiO4]-tetrahedra and the connection between [SiO4]- and [AlO4]-tetrahedra structure were tighter. The sulfide capacity was lager due to the increased sum of basic component, but the increased range was weakened when BaO was more than 3wt-%. The activity of CaO increased and activity coefficient of CaS descended firstly and then enhanced, but the difference between logaCaO and logγCaS tended to be bigger as a function of BaO. The sulfur distribution ratio was in range of 40–50, similar to the variations of sulfide capacity.