Sulfide Phases Research Articles

Urchin-like CuS nanostructures: simple synthesis and structural optimization with enhanced photocatalytic activity under direct sunlight

Wastewater remediation by nanostructured photocatalysts represents a critical issue for nanotechnology. In this work, we employed a facile, low-cost, and one-pot co-precipitation strategy to synthesize a pure hexagonal phase of copper sulfide (CuS) nanostructures at a relatively lower temperature. The produced CuS investigated using different instrumentation. The results confirmed that CuS crystallized in urchin-like nanostructures with a single hexagonal phase exhibiting a band gap of 2.22 eV. The photocatalytic performance of the prepared CuS examined for the photodegradation of malachite green dye (MG) employing direct sunlight illumination. The outcomes showed that the produced CuS featured photodegradation efficiency of 95.5% and 67.2% mineralization within 90 min. Moreover, the kinetic studies of MG photodegradation and the applicability of CuS photocatalyst displayed a pseudo-first-order reaction with high stability at a decent efficiency. This work opens the door for using only prepared single-phase metal chalcogenides in water remediation under direct sunlight.

Investigation of the reduction roasting of saprolite ores in the Caron process: effect of sulphur addition

ABSTRACT Laboratory studies have been undertaken to determine the mechanisms and kinetics of reactions occurring during the reduction roasting of saprolite ores with 1 wt% elemental sulphur addition. The reduction was undertaken using a 15%H2/85%N2 gas mixture at temperatures between 400 and 800°C; nickel was recovered by subsequent leaching in an ammoniacial aqueous solution. The effect of sulphur on dehydroxylation, reduction and sintering was investigated. Improvements in nickel recoveries were obtained when 1 wt% S was added to the nickel-bearing serpentine ore prior to the reduction roasting. Characterisation of the reduced and leached ore samples indicated that this improved Ni recovery with S addition is due to the formation of a leachable nickel sulphide phase, and the suppression of sintering and recrystallisation of the olivine phase formed at high reduction temperatures.

Petrogenetic aspects and role of liquid immiscibility from parts of eastern Deccan volcanic province, India

One atmosphere experimental studies have been conducted on two amygdule‐free representative samples from Khandwa, Madhya Pradesh, Central India, belonging to Eastern Deccan Volcanic province in order to understand mineral petrogenesis, crystallization history of the parent magma and role of liquid immiscibility. One atm experiments were carried out on these two samples at specified temperatures on designated time in order to understand crystallization history. The run products were identified both by optical means and electron microprobe analysis. The identified run products include pyroxenes, feldspar, opaques phase (oxide and sulphide), silica phases, and glass (both brown and colourless variety). The run product pyroxenes belong to quadrilateral pyroxene, and species‐wise correspond to augite, clinoenstatite, and pigeonite. Feldspars in majority are found to be anorthoclase (which are interpreted to have been formed during sudden crystallization in contact with water at shallow depth during experiments) and less commonly calcic plagioclase (in the range of labradorite to anorthite). Opaque phases have both oxide and sulphide, namely hematite, magnetite, martite, and pyrite, respectively. The zoned nature between the oxide and sulphide phases is suggestive of oscillation of oxygen fugacity during crystallization. The run product silica phase corresponds to tridymite. The silica‐rich glass (colourless) is overwhelmingly dominant, whereas silica‐poor glass (brown glass) is a manifestation of liquid immiscibility. The silica‐rich glasses give rise to direct crystallization of tridymite, whereas silica‐poor glasses act as the main driving liquid (or parent liquid) to further the crystallization towards lower temperature. The crystallization behaviour of the parent magma, and liquid immiscibility can be well documented with reference to forsterite‐silica phase diagram; in this phase diagram, the parent liquid corresponds to normative Qtz: 2.542, Fo: 0.098, and En: 0.34. The ambient parent liquid plots very close to Ab apex with reference to the Di‐Ab‐An phase diagram. The clear and distinct zonation pattern present in the opaque phases signifies that crystallization straddles between both oxidizing and reducing condition yielding crystallization of both oxide and sulphide phases. Our study indicates a unique role of liquid immiscibility of the parent magma supplemented by oscillation of oxidizing and reducing conditions giving rise to ensemble of variety of glass compositions, silicate, and opaque phases.

Polymineralic inclusions in oxide minerals of the Afrikanda alkaline-ultramafic complex: Implications for the evolution of perovskite mineralisation

The exceptional accumulation of perovskite in the alkaline-ultramafic Afrikanda complex (Kola Peninsula, Russia) led to the study of polymineralic inclusions hosted in perovskite and magnetite to understand the development of the perovskite-rich zones in the olivinites, clinopyroxenites and silicocarbonatites. The abundance of inclusions varies across the three perovskite textures, with numerous inclusions hosted in the fine-grained equigranular perovskite, fewer inclusions in the coarse-grained interlocked perovskite and rare inclusions in the massive perovskite. A variety of silicate, carbonate, sulphide, phosphate and oxide phases are assembled randomly and in variable proportions in the inclusions. Our observations reveal that the inclusions are not bona fide melt inclusions. We propose that the inclusions represent material trapped during subsolidus sintering of magmatic perovskite. The continuation of the sintering process resulted in the coarsening of inclusion-rich subhedral perovskite into inclusion-poor anhedral and massive perovskite. These findings advocate the importance of inclusion studies for interpreting the origin of oxide minerals and their associated economic deposits and suggest that the formation of large scale accumulations of minerals in other oxide deposits may be a result of annealing of individual disseminated grains.

Hydroconversion of 2-methylnaphtalene and dibenzothiophene over sulfide catalysts in the presence of water under CO pressure

Unsupported highly dispersed nanosized catalysts based on transition metal sulfides were prepared insitu, in water-oil emulsions, by high-temperature decomposition of oil soluble metal precursors using elemental sulfur as sulfiding agent. Their catalytic activity was tested in hydroconversion of 2-methylnaphtalene and dibenzothiophene at 380 °C under H2 pressure of 5 MPa. In addition, the catalysts were tested in the same reactions in the CO−H2O medium (p(CO) = 5 MPa, the CO: H2O molar ratio was 2: 1, ω(H2O) = 20 wt.%) in which hydrogen is formed through a water gas shift reaction (WGSR). Unsupported Ni−Mo-sulfide catalysts were found to be the most active compared to catalysts supported on alumina. Transmission electron microscopy served to investigate the structure and determine general geometric characteristics of Ni−Mo−S particles formed in toluene—water medium by decomposition of transition metal naphthenates and hexacarbonyls in the presence of elemental sulfur under CO pressure. The method described in this study enables one to synthesize nanosized catalysts with a high content of active sulfide phase.

Aportes a la metalogénesis del basamento proterozoico superior-cámbrico de las Sierras Pampeanas Orientales: mineralogía, termometría e isótopos de azufre del skarn Malagueño (Cu- Fe±Zn), Sierra Chica, Córdoba, Argentina

On-going mining operations in a marble quarry (Cantera Centro) from Malagueño, Sierra Chica de Córdoba, Argentina, have unearthed veins, veinlets and lenses of sulfides (pyrrhotite>pyrite≅
 chalcopyrite>>sphalerite). These veins and lenses are up to 0.3 m thick and 2-3 m long, although intermittently can extend about a hundred meters. They are associated with skarns. The metasedimentary host sequence, largely composed of gneisses, amphibolites and marbles, was intruded by amphibolic metagabbro and metadiorite dykes, metatonalite plutons and alkali-feldspar metagranites; the whole complex was metamorphosed into medium to high amphibolite facies and strongly deformed as a result of the a regional event M2-D2/D3 that affected the Neoproterozoic-Cambrian basement during the Pampean orogeny. Except for gneisses, all the other metamorphic lithologies register evidence of differential alteration into skarn, although the process was preferentially developed on marbles, amphibolites and metagranite, and to a lesser exten on mafic and mesosilicic dykes. The metasomatic rocks are characterized by a garnet>>pyroxene skarn (Grs27-48Adr22-34Alm15-27Sps9-21), formed after the replacement of the metagranite; a pyroxene-rich skarn (Hd42-63Di32-50Jo3-5) developed after para-amphibolite, and a garnet (Adr54-71Grs22-40Alm4-7Sps1-2) (±wollastonite) skarn that replaced a calcic marble. The dykes show poor metasomatic replacement and lack sulfides of metasomatichydrothermal origin. Retrograde mineral associations include hastingsite, ferroactinolite, epidote, clinozoisite, sericite, plagioclase (An18), chamosite and calcite. The sulfide mineralization is paragenetically associated with late-stage, infilling skarn-hydrothermal minerals that were sequentially deposited as: calcite→clinochlore→quartz→pyrite→pyrrhotite→chalcopyrite+sphalerite; these phases occur as veins and veinlets within the garnetpyroxene skarn, and as massive pyrrhotite lenses in the piroxene-rich skarn. Microthermometric data from fluid inclusions in sulfide related calcite, together with the geothermometric data from the Fe/Mg ratios in clinochlore and the phase equilibria data from intergrown high and low T ºC pyrrhotite phases, all constrain the infilling gangue phases and sulfide crystallization temperature within the ~360 °C to 250 °C range; the gradual termal decrease is in agreement with the temporal depositional sequence of the infilling phases. Fluid inclusion petrographic data and salinity estimations suggest that sulfide precipitation was triggered by boiling, from a fluid of moderate to high salinity (~14.5 to 33.5 wt% eq. NaCl). Evidence that the fluid evolved under dominantly reducing conditions are the high Fe+2/(Fe+2+Fe+3) ratios and molar proportions of subcalcic garnet (Alm+Sps) in garnet-pyroxene skarn, the presence of fluid inclusion sulfide daughter crystals in calcite, the high H2S/SO42- ratios in the sulfide-bearing fluid and the presence of pyrrhotite among the sulfide phases. Disseminated primary chalcopyrite and pyrite in metagabbro-diorite dykes (Cu ~300 ppm) and the high contents of Cu in amphibolite (~900 ppm) suggest that these protolithic lithologies were the probable sources of metals (Cu>>Zn±Ag). Values of δ34SΣfluid between ~-4 to +1.4‰ obtained from the fractionations factors of pyrite, pyrrhotite and chalcopyrite within the thermal range 350-150 ºC, indicate a magmatic source for sulfur, likely provided by leaching or desulfidation of primary sulfides of the metagabbro-diorite dykes. Metals and sulfur supplied by these dykes and amphibolite would have been redistributed in the skarn after the circulation of the metasomatic-hydrothermal fluids. Skarn bodies would have formed by infiltration of deep metasomatic fluids and fluid-rock interaction which affected lithologies of the Upper Proterozoic-Cambrian metamorphic basement. Fluids could have derived from hidden Cambrian intrusives, or from the surrounding regional migmatization, channeled along lithological contacts and faults/fractures. Field setting, textural and mineralogical evidence of sulfide mineralization in the skarn assemblage of Cantera Centro, suggest a Cambrian age associated to the post-deformational stage of the Pampean Orogeny.

Comparison of Pd and Pd4S based catalysts for partial hydrogenation of external and internal butynes

The partial hydrogenation of but-1-yne and but-2-yne was studied with a view to probing the difference between external and internal alkynes. Catalysts with Pd and Pd4S active phases were prepared on a carbon nanofiber support. Over the simple Pd catalyst over-hydrogenation was common which restricted alkene selectivity greatly – 25–35% depending on temperature. In contrast, the Pd4S active phase offered exceptional alkene selectivity (maximum of 92–93% alkene selectivity for both the external and internal alkyne). DFT calculations were subsequently used to rationalise this difference in product selectivity – sulfur appears to change the geometry of the active site in Pd4S and create a surface which favours alkene desorption relative to over-hydrogenation. This work further emphases the potential of palladium sulfide phases as an alternative to purely metallic palladium catalysts for partial alkyne hydrogenation.

Constraints on the genesis of the Proterozoic bornite dominated copper deposit from Nim ka Thana, western India: An IOCG perspective

The copper mineralization at the southeastern fringe of the Khetri copper belt in western India is primarily hosted within the metapelites and dolomite units of the Mesoproterozoic Ajabgarh Group of rocks. The copper mineralization is well exposed along a NE-SW trending basinal part around Nim ka Thana area where a few of the prospects namely Dokan, Baniwala-ki-Dhani, Dariba, and Nanagwas primarily consist of abundant bornite, chalcopyrite, covellite, digenite, and chalcocite as disseminated phases hosted within a wide-ranging litho units and along quartz-calcite-barite veins. An integrated approach has been adopted to understand the metallogenetic evolution of this bornite dominated copper mineralization. δ13CV-PDB and δ18OV-SMOW results of the carbonate veins ranging from 0.57‰ to −3.75‰ and δ18O range from 15.01‰ to 20.74‰ respectively suggest the influx of hydrothermal fluid in shaping up the deposit. δ13C (CO2) of the ore-bearing fluid ranges from −1.67‰ to 2.65‰ and δ18O (H2O) from 7.11‰ to 12.84‰ respectively also suggest the input of hydrothermal source. The S-isotopic values of Cu-mineralized barite samples range between 16‰ and 20‰, which are lower than that of seawater (δ34S‰ = 20–22‰). This provides the evidence that the barite mineralization could have formed from the hydrothermal fluid that is cogenetic with the late-stage mineralization in a phase-wise separation as an associated mineral assemblage in the system progressively enriching the bornite-rich copper deposit.Based on the field data and evidences, petrographic characteristics, mineral chemistry, fluid inclusion, and stable isotopic signatures, a three-stage mineralization event is proposed as 1) syngenetic precipitation of dispersed bornite-pyrite in a euxinic environment; 2) hydrothermal vein-type mineralization dominated by chalcopyrite-bornite phase, and 3) supergene enrichment of the vein filled mineralization with the development of wide-scale chalcocite-digenetite-covellite mineral phases. Fluid inclusion microthermometry suggests a temperature range from 225°-320 °C with moderate salinity fluid representing epithermal mineralization which is coherent with the stable isotope data (C, O and S isotopes) of the mineralized carbonate and barite veins suggesting the involvement of large scale hydrothermal fluid influx. Te content of various Cu-bearing sulfide phases shows a gradual change in the concentration from chalcopyrite (2.21% to 2.31%), bornite (2.31% to 4.50%), chalcocite (2.77% to 2.87%), digenite (2.57% to 3.70%) and covellite (2.53% to 3.13%) suggesting their evolution from hydrothermal to supergene process. The studied area has experienced wide-scale alterations and Na-metasomatism with the development of associated minerals such as scapolite, tremolite, and sericite. Occurrence of primary and secondary copper sulfides in the metasedimentary sequence, alteration assemblages affected by Na-metasomatism, association of magnetite and specularite in the study area is affiliated to the hydrothermal system akin to IOCG clan as noted from the adjoining Khetri Copper Deposit.

Trace Metal and Cd Isotope Systematics of the Basal Datangpo Formation, Yangtze Platform (South China) Indicate Restrained (Bio)Geochemical Metal Cycling in Cryogenian Seawater

The behaviour of bioavailable trace metals and their stable isotopes in the modern oceans is controlled by uptake into phototrophic organisms and adsorption on and incorporation into marine authigenic minerals. Among other bioessential metals, Cd and its stable isotopes have recently been used in carbonate lithologies as novel tracer for changes in the paleo primary productivity and (bio)geochemical cycling. However, many marine sediments that were deposited during geologically highly relevant episodes and which, thus, urgently require study for a better understanding of the paleo environment are rather composed of a mixture of organic matter (OM), and detrital and authigenic minerals. In this study, we present Cd concentrations and their isotopic compositions as well as trace metal concentrations from sequential leachates of OM-rich shales of the Cryogenian basal Datangpo Formation, Yangtze Platform (South China). Our study shows variable distribution of conservative and bioavailable trace metals as well as Cd isotope compositions between sequential leachates of carbonate, OM, sulphide, and silicate phases. We show that the Cd isotope compositions obtained from OM leachates can be used to calculate the ambient Cryogenian surface seawater of the restricted Nanhua Basin by applying mass balance calculations. By contrast, early diagenetic Mn carbonates and sulphides incorporated the residual Cd from dissolved organic matter that was in isotopic equilibrium with deep/pore waters of the Nanhua Basin. Our model suggests that the Cd isotopic composition of surface seawater at that time reached values of modern oxygenated surface oceans. However, the deep water Cd isotope composition was substantially heavier than that of modern fully oxygenated oceans and rather resembles deep waters with abundant sulphide precipitation typical for modern oxygen minimum zones. This argues for incomplete recycling of Cd and other bioavailable metals shortly after the Sturtian glaciation in the redox stratified Cryogenian Nanhua Basin. Our study highlights the importance of sequential leaching procedures when dealing with impure authigenic sediments such as OM-rich carbonates, mudstones, or shales to achieve reliable trace metal concentrations and Cd isotope compositions as proxies for (bio)geochemical metal cycling in past aquatic systems.

Differential Reactivity of Copper- and Gold-Based Nanomaterials Controls Their Seasonal Biogeochemical Cycling and Fate in a Freshwater Wetland Mesocosm.

Reliable predictions of the environmental fate and risk of engineered nanomaterials (ENMs) require a better understanding of ENM reactivity in complex, biologically active systems for chronic low-concentration exposure scenarios. Here, simulated freshwater wetland mesocosms were dosed with ENMs to assess how their reactivity and seasonal changes in environmental parameters influence ENM fate in aquatic systems. Copper-based ENMs (Kocide), known to dissolve in water, and gold nanoparticles (AuNPs), stable against dissolution in the absence of specific ligands, were added weekly to mesocosm waters for 9 months. Metal accumulation and speciation changes in the different environmental compartments were assessed over time. Copper from Kocide rapidly dissolved likely associating with organic matter in the water column, transported to terrestrial soils and deeper sediment where it became associated with organic or sulfide phases. In contrast, Au accumulated on/in the macrophytes where it oxidized and transferred over time to surficial sediment. A dynamic seasonal accumulation and metal redox cycling were found between the macrophyte and the surficial sediment for AuNPs. These results demonstrate the need for experimental quantification of how the biological and chemical complexity of the environment, combined with their seasonal variations, drive the fate of metastable ENMs.

Formation process of sub-micrometer-sized metasomatic platinum-group element-bearing sulfides in a Tahitian harzburgite xenolith

ABSTRACT Base-metal sulfides (BMSs) are minerals that host platinum-group elements (PGE) in mantle peridotites and significantly control the bulk PGE content. They have been investigated in detail down to the sub-micrometer scale to elucidate PGE behavior in the Earth's interior. Base-metal sulfides are supposedly subjected to supergene and seawater weathering, leading to the redistribution of PGEs at low temperatures. Careful and thorough measurements of BMSs are thus required to elucidate PGE behavior in the Earth's interior. In the present study, a sub-micrometer-sized PGE-bearing sulfide inclusion in a clinopyroxene crystal in a harzburgite xenolith from Tahiti (Society Islands, French Polynesia) was investigated in detail (down to the sub-micrometer scale) using transmission electron microscopy with energy-dispersive X-ray spectroscopy (TEM-EDS). The sulfide inclusion is of carbonatitic metasomatic origin, as it is enveloped by carbonaceous glass, and forms a planar inclusion array with other PGE-bearing sulfide inclusions. The following sulfide phases were identified using TEM-EDS: Fe- and Ni-rich monosulfide solid solutions (MSSs), Fe- and Ni-rich pentlandite, sugakiite, heazlewoodite, chalcopyrite, and Cu-Ir-Pt-Rh-thiospinel (cuproiridsite–malanite–cuprorhodsite). We established the formation process of the metasomatic PGE-bearing sulfide inclusion by considering morphological and mineral characteristics in addition to the chemical composition. A primary MSS first crystallized from metasomatic sulfide melt at ca. 1000 °C, followed by the crystallization of an intermediate solid solution (ISS) below 900 °C. A high-form (high-temperature origin) Fe-rich pentlandite simultaneously crystallized with the primary MSS below ca. 850 °C and recrystallized into a low-form (low-temperature origin) Fe-rich pentlandite below ca. 600 °C. The primary MSS decomposed to Fe- and Ni-rich MSSs, low-form Ni-rich pentlandite, sugakiite, and heazlewoodite. The ISS decomposed to chalcopyrite below ca. 600 °C. Meanwhile, a Cu-Ir-Pt-Rh-thiospinel crystallized directly from the evolved Cu-rich sulfide melt below ca. 760 °C. Thus, Ir, Pt, and Rh preferentially partitioned into the melt phase during the crystallization process of the metasomatic sulfide melt. Metasomatic sulfide melts could be a significant medium for the transport and condensation of Pt together with Ir and Rh during the fractionation process in the Earth's interior. We hypothesize that the compositional variability of PGEs in carbonatites is due to the separation of sulfide melt leading to the loss of PGEs in the carbonatitic melts.

Co–N-doped single-crystal V3S4 nanoparticles as pH-universal electrocatalysts for enhanced hydrogen evolution reaction

The exploitation of innovative and high-efficiency inexpensive electrocatalysts for hydrogen evolution reaction (HER) over a wide pH range is highly pivotal but still challenging. Herein, a simple one-step vacuum pyrolysis approach without using H2S is reported to synthesize Co–N-doped single-crystal V3S4 nanoparticles (Co–N–V3S4), which can function as highly active and stable nonprecious electrocatalysts toward HER at all pH values (pH 0–14). Furthermore, we demonstrate that the use of trithiocyanuric acid as both nitrogen and sulfur sources along with Co-precursor can not only trigger the incorporation of highly active Co–N sites and the high-content N doping, but also well modulate its electronic structure and thus the improved electrocatalytic HER activity. Results show that the as-obtained Co–N–V3S4 material needs small overpotentials of 268 mV, 260 mV and 252 mV at the current density of 10 mA cm−2 in acid (pH 0), neutral (pH 7) and alkaline (pH 14) solutions, respectively, and offers a durable catalytic stability for at least 10 h, as well as gives a Faradaic yield close to 100% at all pH values. Our findings of identifying V3S4 as the catalytically active vanadium sulfide phase for HER and developing a metal-doping induced structure-regulating strategy for the enhancement of catalytic performance broaden our horizons and meanwhile provide fresh insights to rationally design highly efficient noble-metal-free electrocatalysts toward water splitting.

Preparation of TA15 powder reinforced 45CrNiMoY alloy steel with high mechanical property by pre-laid laser cladding technology

Based on the principle of in-situ precipitation strengthening, TA15 powder (Ti-6.5Al-1Mo-1V-1.5Zr) was used as an additive to improve the mechanical properties of 45CrNiMoY alloy steel by pre-laid laser cladding (PLLC) technology. Effects of the content of TA15 powders (0–1.5 wt%) on the microstructure, precipitation mechanism and mechanical property of PLLC 45CrNiMoY alloy steel samples were investigated. Results indicate that TA15 alloy has a significant effect on the microstructure of 45CrNiMoY alloy steel through metallurgical reaction in the laser molten pool. With the increase of TA15 powder content, the granular bainite (GB) microstructure were remarkably refined, the mount of the acicular ferrite (AF) was increased, and in-situ precipitates such as Ti-Y2O3-Zr (TYZ) composite oxide, TiC and ZrC carbide were produced. The 45CrNiMoY alloy steel sample with 1.0 wt% TA15 alloy addition has the best combination of tensile strength (1158 ± 9.7 MPa) and elongation (9.8 ± 0.4%), its microhardness was improved by 25.6% compared with the sample without TA15 powder. The TYZ composite oxides did not only serve as the AF nucleation sites but also spheroidize the detrimental manganese sulfide phase leading to a good elongation of the 45CrNiMoY alloy steel, the TiC and ZrC carbides played a key role in the improvement of the microhardness and tensile strength. The proper addition of TA15 powder can effectively improve the microstructure and mechanical properties of the PLLC 45CrNiMoY alloy steel.

Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration

Using electron probe microanalyzer (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), we analyzed major and trace element compositions of iron oxides from Ni-Cu-PGE sulfide deposits hosted by mafic-ultramafic rocks in northern Fennoscandia, mostly focusing on Finland. The main research targets were the Archean Ruossakero Ni-(Cu) deposit; Tulppio dunite and related Ni-PGE mineralization; Hietaharju, Vaara, and Tainiovaara Ni-(Cu-PGE) deposits; and Paleoproterozoic Lomalampi PGE-(Ni-Cu) deposit. In addition, some reference samples from the Pechenga (Russia), Jinchuan (China), and Kevitsa (Finland) Ni-Cu-PGE sulfide deposits, and a barren komatiite sequence in the Kovero area (Finland) were studied. Magnetite and Cr-magnetite show a wide range of trace element compositions as a result of the variation of silicate and sulfide melt compositions and their post-magmatic modification history. Most importantly, the Ni content in oxide shows a positive correlation with the Ni tenor of the sulfide phase in equilibrium with magnetite, regardless of whether the sulfide assemblage is magmatic or post-magmatic in origin. The massive sulfide samples contain an oxide phase varying in composition from Cr-magnetite to magnetite, indicating that Cr-magnetite can crystallize directly from sulfide liquid. The Mg concentration of magnetites in massive sulfide samples is lowest among the samples analyzed, and this can be regarded as a diagnostic feature of an oxide phase crystallized together with primitive Fe-rich MSS (monosulfide solid solution). Our results show that magnetite geochemistry, plotted in appropriate discrimination diagrams, together with petrographical observations could be used as an indicator of potential Ni-(Cu-PGE) mineralization.

Facile Synthesis of α-Sm2S3/MoS2 Bimetallic Sulfide as a High-Performance Electrochemical Sensor for the Detection of Antineoplastic Drug 5-Fluorouracil in a Biological Samples

Modification of interface between metal sulfide phases is a very promising strategy for designing advanced catalytic materials. Herein, a novel bimetallic sulfide of Molybdenum disulfide covered Samarium sulfide (α-Sm2S3/MoS2) with van der Waals heterogeneous nanostructure was produced for the first time via a simple one-step hydrothermal method. The XRD, FESEM, HRTEM, EDX and XPS results substantiate the successful formation of composite and the modified α-Sm2S3/MoS2 potentially exploited as an electrode for determination of antineoplastic drug 5-Fluorouracil (5-FU). Owing to the rich active sites, synergistic function from α-Sm2S3 and MoS2 and rapid electron transportation, α-Sm2S3/MoS2 sensor platform exhibits considerable electrochemical sensing performance with a linear range from 0.1–1166 μM, and the low detection limit (0.015 μM at S/N = 3). The α-Sm2S3/MoS2 sensing performance is highly selective, stable, and reproducible (with relative standard deviations of 4.28%). The excellent practical utility of the α-Sm2S3/MoS2 sensor comprehends from the quantification of 5-FU in serum and urine samples with acceptable recoveries. Hence, this particular report, open up a paves to design efficient electrode materials by a simple synthesis method for electrochemical application.

Sphere-like Ni3S4/NiS2/MoOx composite modified glassy carbon electrode for the electrocatalytic determination of d-penicillamine

This article describes the synthesis of Ni3S4/NiS2/MoOx composite as an electrode material for the electrocatalytic sensor for d-penicillamine (D-PA). The detection of D-PA is important in biodiagnostics and therapeutic dosage control. The present study compared the performance of Ni3S4/NiS2/GC and Ni3S4/NiS2/MoOx/GC electrodes for the electrocatalytic detection of D-PA. The nickel sulfide phases containing MoOx demonstrated two-fold higher catalytic current response than the controlled one (Ni3S4/NiS2/GC). The excellent performance of the Ni3S4/NiS2/MoOx/GC electrode is confirmed by electrochemical parameters, such as electrochemical charge transfer resistance (133 Ω), diffusion coefficient (3.569 × 10−6 cm2 s−1), and catalytic rate constant (7.415 × 105 M−1 s−1). The Ni3S4/NiS2/MoOx/GC electrode exhibited wide concentration detection of D-PA from 5 to 796 μM with high sensitivity (0.08 μA μM−1), low limit of detection (0.26 μM), and good interference tolerance ability. The proposed electrode was also successfully utilized towards D-PA detection in human urine samples, wherein good recovery ranges (105.6 and 103.5%) were obtained.

Isothermal oxidation kinetics and oxidation behavior of nickel slag

To improve the reduction effect of nickel slag in preparing Fe–Co–Ni–Cu alloy, an oxidization pretreatment was carried out to changing the structure and phase of silicate and sulfide for the nickel slag before the reducing process. The oxidation behavior and kinetics of nickel slag under different temperature and time conditions were discussed. The results shown that in the oxidation process of nickel slag, the part of Fe2SiO4 was oxidized to Fe3O4 and further to Fe2O3, and the other part of Fe2SiO4 directly oxidized to Fe2O3. Meanwhile, the nickel, cobalt and copper in the form of silicate and sulfide were changed into oxides. The changes of the phases are beneficial to the subsequent reduction of nickel slag. The oxidation degree of nickel slag reached 98% under suitable oxidation conditions (900 °C, 15 min). The oxidation kinetic model of nickel slag obtained by Ln–Ln analysis and Model-fitting method was three-dimensional diffusion at lower temperature (300 °C, 400 °C and 500 °C) and random nucleation at higher temperature (700 °C, 900 °C and 1000 °C) respectively. The activation energies obtained by the model method and the model-free method were 28.58 kJ.mol−1 and 26.28 kJ.mol−1 at lower temperature (300 °C, 400 °C and 500 °C) respectively, and the corresponding value were 81.98 kJ.mol−1 and 78.36 kJ.mol−1 at higher temperature (700 °C, 900 °C and 1000 °C) respectively. The activation energy calculated by the two methods was relatively close, and both can be used to calculate the activation energy.

Characterization of Cobalt Sulfide Thin Films Synthesized from Acidic Chemical Baths

Cobalt sulfide thin films were synthesized from acidic chemical baths by varying the deposition time. The powder X‐ray diffraction studies indicated that there are hexagonal CoS, face‐centered cubic Co3S4, and cubic Co9S8 phases of cobalt sulfide. The crystallite size of the hexagonal CoS phase decreased from 52.8 nm to 22.5 nm and that of the cubic Co9S8 phase increased from 11 nm to 60 nm as the deposition time increased from 2 hrs to 3.5 hrs. The scanning electron microscopic images revealed crack and pinhole free thin films with uniform and smooth background and few large polygonal grains on the surface. The band gap of the cobalt sulfide thin films decreased from 1.75 eV to 1.3 eV as the deposition time increased from 2 hrs to 3.5 hrs. The photoluminescence (PL) spectra of the films confirmed the emission of ultraviolet, violet, and blue lights. The intense PL emission of violet light at 384 nm had red shifted with increasing deposition time that could be resulted from the increase in the average crystallite size. The FTIR spectra of the films indicated the presence of OH, C‐O‐H, C‐O, double sulfide, and Co‐S groups. As the deposition time increased, the electrical resistivity of the cobalt sulfide thin films decreased due to the increase in both the crystallite size and the films’ thickness.

NiMoW/P-Al2O3 four-component catalysts with different Mo:W molar ratios and P2O5 contents: the effect of the composition and active phase morphology on the catalytic activity

NiMoW/P-Al2O3 catalysts were synthesized with a different ratio of Mo:W (W-free sample, Mo:W = 2:1, Mo:W = 1:1, Mo:W = 1:2 and Mo-free sample) and various P2O5 contents in the carrier (up to 5 wt%). The surface of the sulfide phase of the samples was investigated by means of high-resolution transmission electron microscopy (HR TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of patterns was estimated in the reactions of hydrodesulfurization of dibenzothiophene (DBT) and hydrogenation of naphthalene. The results are presented in the form of three-dimensional diagrams “P2O5 content—ratio Mo/W—catalytic activity” or “P2O5 content—ratio Mo/W—property”. The influence of the phosphorus content on the maximum peak position of the binding energy S2p/1 of the S2− atomic group for the investigated systems is shown. Comparison of the shape of the curve of changes in the binding energy with the previously presented results on the catalytic activity of the samples in the HDS of a vacuum gas oil allows us to conclude that phosphorus is able to change the electronic state of the active phase of the catalysts, which leads to a change in their catalytic activity in the reactions of HDS.

Isomerization of Linear Paraffin Hydrocarbons in the Presence of Sulfide CoMo and NiW Catalysts on Al2O3—SAPO-11 Support

Supported CoMoS and NiWS catalysts were synthesized on the basis of an Al2O3—SAPO-11 composite support. The acid and texture characteristics of the thus synthesized materials were examined. The morphologies of the active sulfide phase of the catalysts were compared. The kinetic properties of the supported sulfide catalysts in the reaction of hydroisomerization of n-hexadecane and in the hydroprocessing of the diesel fraction were examined. It was shown that it is possible to obtain hydrogenates with improved low-temperature properties in the presence of supported sulfide catalysts containing no noble metals.