Sulfur Enrichment Research Articles

Evolution of chalcophile elements in the magmas of the Bonin Islands

Melt inclusions and submarine volcanic glasses of boninitic composition are well preserved in beach sands from the islands of Chichijima and Mukojima along the Bonin Ridge. Volcanic glass as well as orthopyroxene- and spinel hosted melt inclusions in these sands span almost the entirety of boninite series melt compositions, ranging from >18 wt% to <0.5 wt% MgO. Copper, V and other trace metals were tracked over the entirety of the boninite range and when compared to other suprasubduction melts from the Manus and Lau basins, highlight the variability of these elements across different arc magmas. Boninite series melts show similar behaviour of Cu and V to melts from the Manus and Lau basins, suggestive of magnetite (saturation)-triggered sulfide saturation (a ‘magnetite crisis’). Furthermore, a direct link of these geochemical trends to physical sulfides and magnetite in sample material has been established for the first time. Comparisons of incompatible trace elements suggests that sulfide saturation in the boninite series melts occurred after less fractionation (earlier) than either the Manus or Lau basin melts. This is surprising, given secondary melts such as boninites are generated from melt-depleted mantle sources and are thought to contain very little S. Indeed S contents of melt inclusions of primitive boninitic composition are less than half that of the primitive Manus Basin melts. While the mechanism of sulfur enrichment in the boninite series melts remains a mystery, the oxidised nature of the Bonin Ridge boninites suggests that magnetite-triggered melt reduction is necessary to stabilise sulfide. Finally the timing of magnetite crises generally may be mostly controlled by magmatic oxidation state and total iron contents.

Was Crustal Contamination Involved in the Formation of the Serpentine-Free Udachnaya-East Kimberlite? New Insights into Parental Melts, Liquidus Assemblage and Effects of Alteration

The petrologically unique Udachnaya-East kimberlite (Siberia, Russia) is characterised by unserpentinised and H2O-poor volcaniclastic and coherent units that contain fresh olivine, along with abundant alkali-rich carbonates, chlorides, sulphides and sulphates in the groundmass. These mineralogical and geochemical characteristics have led to two divergent that advocate different origins. It has been suggested that the unserpentinised units from Udachnaya-East are representative of pristine unaltered kimberlite. Conversely, the alkali-chlorine-sulphur enrichment has been attributed to interactions with crustal materials and, or, post-emplacement by brines. The mineralogical and geochemical features and the compositions of melt inclusions in unserpentinised and serpentinised Udachnaya-East kimberlite varieties are compared in this study. Both varieties of kimberlite have similar major, compatible and incompatible trace element concentrations and primitive mantle normalised trace element patterns, groundmass textures and silicate, oxide and sulphide mineral compositions. However, these two kimberlite varieties are distinguished by: (i) the presence of unaltered olivine, abundant Na-K-Cl-S-rich minerals (i.e. chlorides, Sbearing alkali-carbonates, sodalite) and the absence of H2O-rich phases (i.e. serpentine, iowaite (Mg4Fe3+(OH)8OCl•3(H2O)) in unserpentinised samples, and (ii) the absence of alkali- and chlorine-enriched phases in the groundmass and characteristic olivine alteration (i.e. replacement by serpentine and, or, iowaite) in serpentinised samples. In addition, melt inclusions hosted in olivine, monticellite, spinel and perovskite from unserpentinised and serpentinised kimberlite contain identical daughter phase assemblages that are dominated by alkali-carbonates, chlorides and sulphates/sulphides. This enrichment in alkalis, chlorine and sulphur in melt inclusions demonstrates that these elements were an intrinsic part of the parental magma. The paucity of alkali-carbonates and chlorides in the groundmass of serpentinised Udachnaya-East kimberlite is attributed to their instability and removal during post-emplacement alteration. All evidence previously used in support of crustal and brine of the Udachnaya-East kimberlite is thoroughly evaluated. We demonstrate that contamination models are inconsistent with petrographic, geochemical and melt inclusion data. Our combined data suggest that the Udachnaya-East kimberlite crystallised from an essentially H2O-poor, Si-Na-K-Cl-S-bearing carbonate-rich melt.

Arsenate disrupts ion balance, sulfur and nitric oxide metabolisms in roots and leaves of pea (Pisum sativum L.) plants

Arsenic (As) pollution is a significant environmental problem worldwide. Although this metalloid affects plant growth and productivity, it is usually associated with oxidative stress which affects a diverse range of metabolic pathways. However, an additional hazard of As is its presence in edible parts of plants which constitutes a potential animal and human health risk. We exposed 20-d-old pea (Pisum sativum L.) plants, which were used as a model due to their agronomic importance, to 50 μM arsenate (AsV). We then analyzed physiological and biochemical parameters in roots and leaves to determine the principal metabolic characteristics of sulfur, reactive oxygen and nitrogen species (ROS and RNS) metabolisms as well as NADPH-regenerating systems. AsV triggered a significant reduction in growth parameters and an increase in oxidative markers (lipid and protein oxidation) in both roots and leaves. In addition, AsV induced a high level of biosynthesis of enriched sulfur compounds such as phytochelatins (PC2 and PC3) in both roots and leaves, with a concomitant decrease in reduced glutathione (GSH) content. These changes were accompanied by alterations in antioxidative enzymes, the NADPH-regenerating system and nitric oxide (NO) metabolism. In roots, these changes were associated with a significant increase in the amino acids proline, glycine, glutamic acid and γ-aminobutyric acid (GABA) content as well as endopeptidase activity. Analysis of AsV-treated 63-d-old pea plants, which had already developed pods, also showed that As is mainly restricted to roots. Although our results indicate that 50 μM AsV causes a differential metabolic response in roots and leaves, the biochemical adaptation of roots to palliate the negative impact of As is more pronounced. This may enable pea plants to survive by restricting As accumulation in roots and by reducing the level of As in the edible parts of the pea plant (fruits).

Efficient Extraction of Sulfur and Nitrogen Mustards from Nonpolar Matrix and an Investigation on Their Sorption Behavior on Silica.

Extraction of vesicant class of chemical warfare agents (CWAs) such as sulfur mustard and nitrogen mustards from the environmental matrices is of prime importance, from a forensic and verificationviewpoint of the Chemical Weapons Convention (CWC). For extraction of Convention Related Compounds from nonpolar organic medium, commercially available silica cartridges are used extensively, but silica cartridges exhibit limited efficiency toward vesicant classes of compounds. It is expected that sulfur mustard being nonpolar does not retain sufficiently on silica surface, and nitrogen mustards (being basic) are strongly adsorbed on acidic silica surface, resulting in their poor recoveries. Contrary to the expected higher recovery of sulfur mustard over nitrogen mustards, it was observed that the recovery of sulfur mustard was lower than that of nitrogen mustards with the silica based sorbent. The reason for this typical behavior of these agents on silica was investigated. This study was aimed to develop an analytical method for efficient extraction and enrichment of sulfur and nitrogen mustards from hydrophobic matrices. In this work, the polymeric sorbent was synthesized with polar methacrylic acid (MAA) as monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker and used for solid phase extraction (SPE) of sulfur mustard and nitrogen mustards. The extraction efficiency of the polymeric sorbent was optimized and compared with that of silica cartridges. Both classes of analytes were recovered in good amounts from the polymeric sorbent compared to silica. The extraction parameters were optimized for the proposed method which included extraction solvent ethyl acetate and washing solvent n-hexane (1 mL). The recoveries of the analytes ranged from 75 to 87% with relative standard deviations (RSDs) lower than 9%. The limit of detection (LOD) was found to be in the range of 0.075-0.150 μg mL-1, and limit of quantification (LOQ) was >0.25 μg mL-1. The linear dynamic range of optimized method was found to be 0.50-20 μg mL-1 ( r2 = 0.9994) for sulfur mustard and 0.25-20 μg mL-1 ( r2 = 0.9897-0.9987) for nitrogen mustards, respectively.

Hydrogen evolution enhancement of ultra-low loading, size-selected molybdenum sulfide nanoclusters by sulfur enrichment

Size-selected molybdenum sulfide (MoSx) nanoclusters obtained by magnetron sputtering and gas condensation on glassy carbon substrates are typically sulfur-deficient (x = 1.6 ± 0.1), which limits their crystallinity and electrocatalytic properties. Here we demonstrate that a sulfur-enriching method, comprising sulfur evaporation and cluster annealing under vacuum conditions, significantly enhances their activity towards the hydrogen evolution reaction (HER). The S-richness (x = 4.9 ± 0.1) and extended crystalline order obtained in the sulfur-treated MoSx nanoclusters lead to consistent 200 mV shifts to lower HER onset potentials, along with two-fold and more-than 30-fold increases in turnover frequency and exchange current density values respectively. The high mass activities (∼111 mA mg−1 @ 400 mV) obtained at ultra-low loadings (∼100 ng cm-2, 5% surface coverage) are comparable to the best reported MoS2 catalysts in the literature.

Effect of synthetic conditions on the morphology and gasoline desulfurization performance of microphase-separated membranes

Multicomponent polymer membranes containing poly(acrylonitrile-co-glycidyl methacrylate) (PANGMA) and ethyl cellulose (EC) were prepared under different synthetic conditions for gasoline desulfurization by pervaporation. Transmission electron microscopy was employed to study the morphologies of the PANGMA-EC membranes obtained under different synthetic conditions. The results showed that PANGMA-EC membranes had distinct microphase separation consisting of a dispersed EC phase and a continuous PANGMA phase. With increasing reaction temperature, the dispersed EC phase in the shape of isolated islands became smaller and more closely packed. Moreover, when decreasing the reaction concentration and the catalyst amount, the island phase composed of EC became smaller and mostly exhibited a long strip morphology. According to the analysis of the morphologies of the microphase-separated structures of the PANGMA-EC membranes obtained under different synthetic conditions, it was predicted that the permeation characteristics of gasoline components through the PANGMA-EC membranes increased with increasing reaction temperature and with decreasing reaction concentration and catalyst amount. This was verified by sorption and pervaporation experimental results of the PANGMA-EC membranes obtained under different synthetic conditions. Therefore, for the PANGMA-EC microphase-separated membrane, the modification of synthetic condition could contribute to higher permeation flux and sulfur enrichment factor compared with other reported membrane materials.

Band-gap tuning of Cu2ZnSn(S,Se)4 solar cell absorbers via defined incorporation of sulphur based on a post-sulphurization process

We demonstrate that based on a post-sulphurization approach the mean sulphur concentration and bandgap of Cu2ZnSn(S,Se)4 (CZTSSe) solar cell absorber layers can be precisely controlled. However, X-ray diffraction and secondary ion mass spectrometry studies reveal an inhomogeneous sulphur incorporation at lower process temperatures resulting in a sulphur gradient in the absorber. Optimization of such gradients may enable further performance improvement of future devices. During the post-sulphurization process sulphur seems to accumulate at the back of the absorber first where there is already an enrichment of sulphur in the purely selenized absorbers. With higher temperatures more sulphur gets incorporated and the sulphur distribution gets evened out. Morphology studies show that the process of exchanging the chalcogenides leaves behind holes and results in a porous absorber layer. With higher process temperatures and therefore higher sulphur content the absorber gets more dense. The device performance of the post-sulphurized samples increases significantly with increasing process temperature and increasing sulphur content.

A water-based mixing process for fabricating ZIF-8/PEG mixed matrix membranes with efficient desulfurization performance

In this article, ZIF-8 nanoparticles were synthesized in water and directly added to a polyethyleneglycol (PEG) aqueous solution (water-based mixing process) to prepare ZIF-8/PEG mixed matrix membranes (MMMs) for pervaporation desulfurization. The structure and properties of ZIF-8 particles were characterized by Fourier Transform-Infrared Spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET analysis. The surface composition and structural morphology of all ZIF-8/PEG MMMs were systematically investigated by FT-IR and SEM. The effect of ZIF-8 content on the pervaporation performance of ZIF-8/PEG membranes was investigated. Versus pure PEG membranes, both the total flux and the sulfur enrichment factor of the ZIF-8/PEG MMMs were remarkably increased. This phenomenon is attributed to the good compatibility between PEG and ZIF-8 particles and the high thiophene selective sorption of ZIF-8 particles (confirmed by molecular simulation). Optimal pervaporation performance was achieved at a 4 wt% loading of ZIF-8 particles with the flux of 1.96 kg/(m2 h) and the sulfur enrichment factor of 8.93. These increased by 397.46% and 18.75% versus pristine PEG membrane, respectively. In addition, the effect of operation temperature and feed sulfur content on membrane performance were also systematically investigated.

Influence of Polyethylene Glycol on the Deep Desulfurization of Catalytic Cracking Gasoline by Polyurethane Membranes via Pervaporation

Polyethylene glycol (PEG) is an important additive that can effectively improve the desulfurization performance of polyurethane membranes for fluid catalytic cracking (FCC) gasoline via pervaporation (PV). Polyurethane membranes were characterized using Fourier transform infrared spectroscopy (FT-IR) analysis and X-ray diffraction techniques. Permeation vaporization experiments were carried out for sulfur-containing compounds in FCC gasoline using homemade polyvinylidene fluoride (PVDF) bottom membranes. Compared with the traditional osmogasification membrane, the PEG/polyurethane (PU) hybrid membrane shows a higher sulfur enrichment factor (6.00) and permeation flux (2.20 kg/(m2·h)), which confirms the superior performance of the proposed PU membrane. Through the analysis of meteorological chromatography, it can be clearly observed that the PEG/PU membrane can effectively remove the thiophene and its derivatives in FCC gasoline.

Geochemical characteristics of n-alkanes and isoprenoids in coal seams from Zhuji coal mine, Huainan coalfield, China, and their relationship with coal-forming environment.

Ten coal seams in Upper Shihezi Formation, Lower Shihezi Formation, and Shanxi Formation from the Zhuji mine, Huainan coalfield, China, were analyzed for n-alkanes and isoprenoids (pristine and phytane) using gas chromatography-mass spectrometry (GC-MS), with an aim of reconstructing the coal-forming plants and depositional environments along with organic carbon isotope analyses. The total n-alkane concentrations ranged from 34.1 to 481mg/kg. Values of organic carbon isotope (δ13Corg) ranged from - 24.6 to - 23.7‰. The calorific value (Qb,d), maximum vitrinite reflectance (Romax), proximate, and ultimate analysis were also determined but showed no correlation with n-alkane concentrations. Carbon Preference Index (CPI) values ranged from 0.945 to 1.30, suggesting no obvious odd/even predominance of n-alkane. The predominance of C11 and C17 n-alkanes implied that the coal may be deposited in the fresh and mildly brackish environment. According to the contrary changing trend of pristine/phytane (Pr/Ph) ratio and boron concentrations, Pr/Ph can be used as an indicator to reconstruct the marine transgression-regression in sedimentary environment of coal formation. The influence of marine transgression may lead to the enrichment of pyrite sulfur in the coal seam 4-2. C3 plants (- 32 to - 21‰) and marine algae (- 23 to - 16‰) were probably the main coal-forming plants in the studied coal seams. No correlation of the n-alkane concentration and redox condition of the depositional environment with organic carbon isotope composition were found.

Post-collisional alkaline magmatism as gateway for metal and sulfur enrichment of the continental lower crust

Mafic and ultramafic magmas that intrude into the lower crust can preserve evidence for metal and sulfur transfer from the lithospheric mantle into the lower continental crust. Here we focus on a series of ultramafic, alkaline pipes in the Ivrea Zone (NW Italy), which exposes deeply buried (6–11 kbar), migmatitic metasedimentary rocks intruded by voluminous basaltic magmas of the Mafic Complex, a major crustal underplating event precisely dated via U/Pb CA-IDTIMS on zircon at 286.8 ± 0.4 Ma. The ultramafic pipes postdate the Mafic Complex and from 100 to 300 m wide cumulate-rich conduits. They are hydrated and carbonated, have unusually high incompatible element concentrations and contain blebby and semi-massive Ni-Cu-PGE sulfide mineralisation. The sulfides occur as coarse intergranular nodules (>10 mm) and as small intragranular blebs (<1 mm) hosted in olivine, and have homogeneous, mantle-like δ34S (+1.35 ± 0.25‰). This homogeneity suggests that the pipes reached sulfide supersaturation without addition of crustal sulfur, and that the δ34S signature is representative of the continental lithospheric mantle. One of the pipes, the 249 Ma Valmaggia pipe, carries a very distinctive Sr-Nd-Hf-Pb isotopic composition in its core (87Sr/86Sr 0.70250, εNd-18, εHf-18, 206Pb/204Pb 16.0, 207Pb/204Pb 15.16, 208Pb/204Pb 35.87), very different from the margin of this pipe and from other pipes that have higher 87Sr/86Sr, εNd and 206Pb/204Pb. The unusual isotopic composition of the Valmaggia pipe requires a source with long-term (2500–1500 million years) U-, Th- and Rb-depletion and LREE enrichment. Such compositions are found in Late Archean/Early Proterozoic granulites and lower crustal xenoliths. We suggest that the unusual isotopic composition of the Valmaggia pipe reflects contamination of the mantle source of the pipe with a crustal component that is neither represented in the local Paleozoic crust nor in the isotopically anomalous hydrated mantle inferred as the source of the large-volume mafic underplate that formed the Mafic Complex. During post-collisional gravitational collapse of the Variscan Orogen, this source produced the alkaline, metal (Ni, Cu, PGE)- and volatile (H2O, CO2, S)-rich mafic–ultramafic magma that formed the deep-crustal intrusion at Valmaggia. U/Pb dating of other chemically and geologically comparable pipes in the area shows that this process was active over at least 40 Ma. The Ivrea pipes illustrate how the lower continental crust can be fertilised with mantle-derived metals and volatiles, which are available for later remobilisation into upper-crustal ore systems. World-class mineral deposits along the margins of lithospheric blocks may thus be the result of both favourable crustal architecture (focussing of magmas and fluids) and localised volatile and metal enrichment of the lower crust related to mantle-derived hydrous metasomatism.

Interface engineering of Cu(In,Ga)Se2 and atomic layer deposited Zn(O,S) heterojunctions

Atomic layer deposition of Zn(O,S) is an attractive dry and Cd-free process for the preparation of buffer layers for chalcopyrite solar modules. As we previously reported, excellent cell and module efficiencies were achieved using absorbers from industrial pilot production. These absorbers were grown using a selenization/sulfurization process. In this contribution we report on the interface engineering required to adapt the process to sulfur-free multi source evaporated absorbers. Different approaches to a local sulfur enrichment at the heterojunction have been studied by using surface analysis (XPS) and scanning transmission electron microscopy. We correlate the microstructure and element distribution at the interface with device properties obtained by electronic characterization. The optimized completely dry process yields cell efficiencies >16% and 30 × 30 cm2 minimodule efficiencies of up to 13.9% on industrial substrates. Any degradation observed in the dry heat stress test is fully reversible after light soaking.

Tempo of magma degassing and the genesis of porphyry copper deposits

Porphyry deposits are copper-rich orebodies formed by precipitation of metal sulphides from hydrothermal fluids released from magmatic intrusions that cooled at depth within the Earth’s crust. Finding new porphyry deposits is essential because they are our largest source of copper and they also contain other strategic metals including gold and molybdenum. However, the discovery of giant porphyry deposits is hindered by a lack of understanding of the factors governing their size. Here, we use thermal modelling and statistical simulations to quantify the tempo and the chemistry of fluids released from cooling magmatic systems. We confirm that typical arc magmas produce fluids similar in composition to those that form porphyry deposits and conclude that the volume and duration of magmatic activity exert a first order control on the endowment (total mass of deposited copper) of economic porphyry copper deposits. Therefore, initial magma enrichment in copper and sulphur, although adding to the metallogenic potential, is not necessary to form a giant deposit. Our results link the respective durations of magmatic and hydrothermal activity from well-known large to supergiant deposits to their metal endowment. This novel approach can readily be implemented as an additional exploration tool that can help assess the economic potential of magmatic-hydrothermal systems.

Phase-controlled solvothermal synthesis and morphology evolution of nickel sulfide and its pseudocapacitance performance

Phase-controlled solvothermal synthesis has been proposed for the synthesis of nickel sulfide of single phase including α-NiS, Ni3S4 and NiS2 by tuning the reaction time and the addition of surfactant. The phase evolution of nickel sulfide proceeds with the increase of sulfur stoichiometry with longer reaction time in the presence of surfactant. With the addition of hexadecyl-trimethyl-ammonium bromide (CTAB), a higher sulfur stoichiometry NiS2 phase with hollow sphere geometry was synthesized at 9h, a much shorter time due to the enrichment of S2− on CTAB micelle surface, followed by the transformation to single phase Ni3S4 finally due to dissipation of enriched sulfur to the bulk solution. The application of these three single phase materials in supercapacitors was investigated. The α-NiS electrode material outperformed the Ni3S4 and NiS2 electrodes, exhibiting a much higher specific capacitance of 800Fg−1 at 0.5Ag−1, attributable to the small particle size, high electrical conductivity and the unique hexagonal crystal structure.

Influence of a tundra freeze-thaw cycle on sulfide oxidation and metal leaching in a low sulfur, granitic waste rock

Drill cuttings were collected at 1 m depths from an instrumented, low sulfur, experimental waste rock pile containing a 4C-pyrrhotite that had been exposed to the extreme freeze-thaw cycle of a tundra climate. Boreholes were drilled from the top to base in the center of the pile and near the core-batter transition. Waste rock samples were analyzed for carbon, sulfur, and metal concentrations; sulfur oxidation states; and variation in iron and nickel forms due to oxidative dissolution of pyrrhotite. Results from X-ray absorption spectroscopy and aqueous extraction experiments were used to relatively compare samples from various depths in the boreholes, which indicate sulfide weathering fronts that decrease in intensity from the top to core to base at the center of the pile and from the core-batter transition to the center of the pile. The tundra climate and waste pile configuration produce a permafrost base, a seasonally frozen core, and an atmospheric-like zone near the surface. The fluctuation of the freeze-thaw cycle caused the greatest sulfide weathering near the surface and lesser weathering in the core and base of the pile. Metal- and sulfur-rich leachate from the higher weathering zone likely is collecting on a variable and seasonal frozen surface beneath the surface layer that causes metals and S to precipitate and (or) sorb during a portion of the year. The accumulation of sulfur and metals with the flux of this frozen surface produces a nickel and possibly an iron and sulfur enrichment zone beneath the surface layer in the center of the pile. The weathering front from the top to core to base of the pile and from core-batter transition to the core corresponds to a previously formulated leachate model, but the enrichment zone below the surface zone is unique to this conceptual waste-rock weathering model for this tundra climate.

Pyrrhotite mineralization as a search criterion for sulfide deposits at sediment-covered spreading centers

Pyrrhotite ores forming the hydrothermal vents of the Hydrothermal Hills in the Southern Trough of the Guaymas depression were studied. A series of features pointing to the occurrence of surface and buried sulfide deposits of pyrrhotite mineralization was revealed: the presence of pyrrhotite associations to hydrocarbons of oil series; low concentrations of Cu, Zn, and Pb; the enrichment of sulfur of pyrrhotite and hydrogen sulfide of hydrothermal solutions in heavy 34S isotope by 5–7%; and the heavy isotope composition of carbon in naphthoid compounds. The results obtained allow one to suggest searching for large sulfide deposits at active rifts of high spreading and sedimentation rates, i.e., at near-continental rifts of the humid zone of avalanche sedimentation.

Cyclic Use of Ladle Furnace Refining Slag for Desulfurization

Industrial experiments were carried out to study the cyclic use of ladle furnace refining slag on desulfurization. Sampling of refining slag and steel were undertaken simultaneously at roughly equal intervals of time. The desulfurization capacity remained almost unchanged in the recycling slag compared with the primary slag. The amount of lime added was gradually increased each time when the slag was reused. As a result, the basicity increased, and therefore the sulfide capacity (Cs) increased. Cs reached a maximum when the lime added was 816 kg. The effect of sulfur enrichment on desulfurization reaction in ladle furnace slag-recycled process could be partially offset mainly by two aspects: the amount of slag increased with increases in the number of times recycled slag reused and in the quantity of lime added, which could directly reduce the mass fraction of sulfur in the recycled slag; on the other hand, during the process of transport, casting, and pouring recycled slag into next ladle, a part of CaS in the recycled slag has opportunity to be oxidized by air. Based on such favorable conditions for desulfurization, a final desulfurization ratio of up to 82.6 % was obtained, and the end-point sulfur content can be reduced to about 40 ppm.

Elemental zonation in marine concrete

This paper presents a large collection of microstructural studies on concretes exposed to marine environments for periods between 2 and 34years. The phase changes were studied using optical as well as scanning electron microscopy. A total of 21 concretes, taken from 9 different locations along the Norwegian and Danish coastlines, were investigated. Chemical zonation and mineralogical zonation were observed in the surface regions of marine-exposed concrete. Three zones were found irrespective of the age, location or binder composition: a magnesium-rich zone, a sulfur-rich zone, and a chlorine-rich zone. The absence of major damage indicates that the observed phase changes led only to minor scaling. This suggests that, rather than sulfate attack, sea water merely causes sulfur enrichment.

Gasoline desulfurization by a TiO2‐filled ethyl cellulose pervaporation membrane

ABSTRACTThe TiO2 nanoparticles were incorporated into an ethyl cellulose (EC) matrix to improve the pervaporation (PV) performance of the membrane for gasoline desulfurization. The microstructures of different EC membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray and transmission electron microscopy. The PV experiments showed that the hybrid membrane of EC/TiO2 demonstrated an improved permeation flux (J) of 7.58 kg m−2 h−1 and a sulfur enrichment factor (α) of 3.13 in comparison with the pure EC membrane, with a J of 3.73 kg m−2 h−1 and an α of 3.69. In addition, the effects of the operating conditions, including the operating temperature, layer thickness, crosslinking time, feed flow rate, and feed sulfur content level, on the PV performance of the EC/TiO2 membrane were investigated. Under a 100 mL/min feed flow rate and a 85 μg/g sulfur content, J of the 10 μm thick membrane increased to 7.58 kg m−2 h−1 with α of 3.13 compared to the pure EC membrane (3.73 kg m−2 h−1, 3.69) at 80 °C with 30 min of crosslinking time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017: 134, 43409.

Experimental study on sulfur removal from ladle furnace refining slag in hot state by blowing air

In view of the present problem of sulfur enrichment in the metallurgical recycling process of ladle furnace (LF) refining slag, a simple and efficient method of removing sulfur from this slag was proposed. The proposed method is compatible with current steelmaking processes. Sulfur removal from LF refining slag for SPHC steel (manufactured at a certain steel plant in China) by blowing air in the hot state was studied by using hot-state experiments in a laboratory. The FactSage software, a carbon/sulfur analyzer, and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy were used to test and analyze the sulfur removal effect and to investigate factors influencing sulfur removal rate. The results show that sulfur ions in LF refining slag can be oxidized into SO2 by O2 at high temperature by blowing air into molten slag; SO2 production was observed to reach a maximum with a small amount of blown O2 when the temperature exceeded 1350°C. At 1370°C and 1400°C, experimental LF refining slag is in the liquid state and exhibits good fluidity; under these conditions, the sulfur removal effect by blowing air is greater than 90wt% after 60 min. High temperature and large air flow rate are beneficial for removing sulfur from LF refining slag; compared with air flow rate, temperature has a greater strongly influences on the sulfur removal.