Extraction Of Sulfur Research Articles

The Impact of Waste Application on the Reclamation and Biological Life of Degraded Soils

This work concerns the assessment of soil reclamation and its impact on biological life in areas destroyed by the sulfur industry in Jeziórko. Sulfur extraction using the borehole method causes enormous destruction to the soil environment. Among the many forms of degradation, the most pronounced are the chemical transformations of the environment and the disturbances in water relations in large areas, which could theoretically impact areas not within the direct range of the mining plant. This work aimed to assess the condition of biological life in soil reclaimed with waste in areas devastated by the sulfur industry in Jeziórko. The reclamation of these soils was difficult but necessary due to the complete disappearance of biological life. Appropriate actions were taken to restore and improve the properties of the soil, which resulted in an improvement in their production capacity. Reclamation was carried out, among other techniques, by deacidifying the soil using post-flotation lime and fertilizing the soil with municipal sewage sludge and post-use mineral wool. Studies have shown an improvement in many soil properties, such as its physical, water, chemical, and biological properties. The implemented reclamation methods significantly influenced, among other things, the density and water properties of the degraded soil. The soil reclaimed with mineral wool and sewage sludge recorded the highest density and water capacity. Applying mineral wool to the degraded soil influenced the changes in the analyzed physical and water properties. The obtained research results also show the beneficial effect of mineral wool and sewage sludge on the increase in organic carbon content. In the soil treated with these substances, the organic carbon content ranged from 13.60 g·kg−1 to 14.30 g·kg−1. It is shown that reclamation has had a considerable impact on and is essential for biological life in Jeziórko.

First findings of platinum group minerals from ultramafites of the Idzhim mafic-ultramafic massif (Western Sayan)

In plastically deformed harzburgite and dunite of the Idzhim mafic-ultramafic massif, which is part of the Kurtushiba ophiolite belt of the Western Sayan and is one of largest massifs of this belt, platinum group minerals (PGM) were identified for the first time. They were found in pentlandite, awaruite and nickel arsenides (NiS, Ni2S) in form of finely dispersed inclusions, the diagnosis of which, due to their small size, was carried out only qualitatively. Native osmium, Ir-bearing osmium, native ruthenium, garutiite, tetraferroplatinum, unnamed (Pt,Ir)Fe and (Ni,Cu,Pd,Pt)2-3Fe phases, zaccarinite, Ir-bearing erlikmanite and unnamed sulfides with crystal chemical formula Me2S were quantitatively identified and characterized. All PGM grains found are predominantly localized either in peripheral parts of grains of sulfides, awaruite and wairauite, or in silicate matrix in immediate vicinity of these minerals. The platinum group elements (PGE) content and their distribution in restite ultramafic rocks was apparently controlled by partial melting of primary peridotite substrate. During partial melting, the extraction of sulfur and Pt-group platinoides (Pt, Pd, Rh) into the silicate melt led to a decrease in S2 fugacity and the accumulation of Ir-group platinoides (Os, Ir, Ru) in monosulfide solid solution (mss), from which subsequently primary Os-Ir-bearing pentlandite crystallized. The subsequent transformation of this sulfide led to appearance of PGE-containing awaruite and nickel arsenides, as well as to everything discovered diversity of identified PGM.

Procedures from samples to sulfur isotopic data: A review.

Sulfur isotopes have been widely used to solve some key scientific questions, especially in the last two decades with advanced instruments and analytical schemes. Different sulfur speciation and multiple isotopes analyzed in laboratories worldwide and in situ microanalysis have also been reported in many articles. However, methods of sampling to measurements are multifarious, and occasionally some inaccuracies are present in published papers. Vague methods may mislead newcomers to the field, puzzle readers, or lead to incorrect data-based correlations. We have reviewed multiple methods on sulfur isotopic analyses from the perspectives of sampling, laboratory work, and instrumental analysis in order to help reduce operational inhomogeneity and ensure the fidelity of sulfur isotopic data. We do not deem our proposed solutions as the ultimate standard methods but as a lead-in to the overall introduction and summary of the current methods used. It has been shown that external contamination and transformation of different sulfur species should be avoided during the sampling, pretreatment, storage, and chemical treatment processes. Conversion rates and sulfur isotopic fractionations during sulfur extraction, purification, and conversion processes must be verified by researchers using standard or known samples. The unification of absence of isotopic fractionation is needed during all steps, and long-term monitoring of standard samples is recommended. This review compiles more details on different methods in sampling, laboratory operation, and measurement of sulfur isotopes, which is beneficial for researchers' better practice in laboratories. Microanalyses and molecular studies are the frontier techniques that compare the bulk sample with the elemental analysis/continuous flow-gas source stable isotope ratio mass spectrometry method, but the latter is widely used. The development of sulfur isotopic measurements will lead to the innovation in scientific issues with sulfur proxies.

Coupling Electrochemical Sulfion Oxidation with CO2 Reduction over Highly Dispersed p‐Bi Nanosheets and CO2‐Assisted Sulfur Extraction

AbstractWe report herein an electrocatalytic CO2 reduction‐coupled sulfion oxidation system for the co‐productions of valuable formate and sulfur at much enhanced atom utilization. Specifically, an organic ligand‐assisted two‐step reconstruction approach has been developed to fabricate the highly dispersed p‐Bi nanosheets (p‐Bi NSs) for cathodic CO2 reduction reaction (CO2RR), and meanwhile porous Co−S nanosheets (Co−S NSs) was applied for anodic sulfion oxidation reaction (SOR). Significantly high Faradaic Efficiencies of about 90 % for formate production by CO2RR in a wide potential range from −0.6 V to −1.1 V, and excellent SOR performances including an ultra‐low onset potential of about 0.2 V and recycle capacity of S2− in the 0.1 M and 0.5 M S2− solutions, have been simultaneously achieved. In the meantime, both the structure transformation of the catalysts and the reaction pathways are explored and discussed in detail. A two‐electrode CO2RR||SOR electrolyzer equipped with above electrocatalysts has been established, which features as low as about 1.5 V to run the electrolyzer at 100 mA cm−2, manifesting extremely lowered electricity consumption in comparison to conventional CO2RR system. Moreover, a sulfur separation approach has been proposed by using CO2, which is efficient, environmentally friendly and cost effective with value‐added NaHCO3 be obtained as the byproduct.

Coupling Electrochemical Sulfion Oxidation with CO2 Reduction over Highly Dispersed p-Bi Nanosheets and CO2 -Assisted Sulfur Extraction.

We report herein an electrocatalytic CO2 reduction-coupled sulfion oxidation system for the co-productions of valuable formate and sulfur at much enhanced atom utilization. Specifically, an organic ligand-assisted two-step reconstruction approach has been developed to fabricate the highly dispersed p-Bi nanosheets (p-Bi NSs) for cathodic CO2 reduction reaction (CO2 RR), and meanwhile porous Co-S nanosheets (Co-S NSs) was applied for anodic sulfion oxidation reaction (SOR). Significantly high Faradaic Efficiencies of about 90 % for formate production by CO2 RR in a wide potential range from -0.6 V to -1.1 V, and excellent SOR performances including an ultra-low onset potential of about 0.2 V and recycle capacity of S2- in the 0.1 M and 0.5 M S2- solutions, have been simultaneously achieved. In the meantime, both the structure transformation of the catalysts and the reaction pathways are explored and discussed in detail. A two-electrode CO2 RR||SOR electrolyzer equipped with above electrocatalysts has been established, which features as low as about 1.5 V to run the electrolyzer at 100 mA cm-2 , manifesting extremely lowered electricity consumption in comparison to conventional CO2 RR system. Moreover, a sulfur separation approach has been proposed by using CO2 , which is efficient, environmentally friendly and cost effective with value-added NaHCO3 be obtained as the byproduct.

Effect of thermal pretreatment on the two-stage extraction of aluminum, sulfur and potassium from a fine-quartz bearing alunite

The extraction of aluminum, sulfur, and potassium from an alunite ore (Ghazvin, Iran) was studied by roasting followed by two-stage alkaline leaching. In the roasting stage, the effects of several key parameters including temperature (520 to 620 °C), reaction time (30–150 min), particle size (0.075 to 10 mm), and furnace medium (with and without diesel fuel and with charcoal) were investigated on the leachability of sulfur and potassium by sodium carbonate and of aluminum by sodium hydroxide. The first leaching stage was carried out with sodium carbonate at a pulp density of 20% (w/w), a reaction time of 4 h, a particle size of less than 75 µm, a temperature of 95 °C and a ratio of sodium carbonate to alunite of 1.5:1. The highest extractions of sulfur and potassium (99.9 % for both elements) were obtained with the ore roasted at 620 °C, a particle size of 3 mm, and a roasting time of 90 min. The extractions were significantly increased by increasing the temperature and roasting time. The second stage of leaching was conducted at the temperature of 95 °C, leaching time of 6 h and the sodium hydroxide concentration of 5 M at 15 % pulp density. The highest aluminum extraction (95.3 %) was obtained by reductive roasting with charcoal at a temperature of 570 °C, a roasting time of 30 min, and a particle size of less than 3 mm. For potassium and sulfur extraction, increasing the roasting temperature, reaction time and diesel fuel addition (above 3%) resulted in a decrease in aluminum extraction, which was attributed to the conversion of the alumina phase to a stable phase. The results of this study show that alunite ore could be an interesting alternative for alumina production.

Extraction of sulfur (IV) oxide, nitrogen oxides and carbon oxide from flue gases using a sorbent under conditions of its mechanical activation

The paper substantiates the feasibility of creating an adsorption technology with controlled activation of the adsorbent for the removal of sulfur dioxide, nitrogen oxides, and carbon from the flue gases of coal-fired power plants. In laboratory conditions, the effect of mechanical activation on the adsorption capacity of ash was studied. It is shown that the controlled mechanical activation is able to increase the adsorption capacity of ash relative to sulfur dioxide by 2.7 times, to nitrogen oxides by 2.1 times, to carbon monoxide by 5 times or more.

Recovery of zinc and extraction of calcium and sulfur from zinc-rich gypsum residue by selective reduction roasting combined with hydrolysis

A novel process that includes selective reduction roasting followed by hydrolysis was proposed in this work to recover zinc, and efficiently extract calcium and sulfur from hazardous zinc-rich gypsum residue (ZGR) waste for high-purity of CaCO3 and sulfur production. The selective reduction behaviors of ZGR during the reduction roasting were investigated in detail based on thermodynamic analysis and roasting experiments. The effect of roasting temperature, carbon dosage and time on the selective reduction of ZGR was comprehensively investigated, and the results indicated that ZnO and CaSO4 in the ZGR can be selectively reduced to Zn(g) and CaS, respectively. The volatile Zn(g) was oxidized to ZnO and enriched in the dust, which can be used as a secondary zinc resource. Moreover, the hydrolysis behaviors and leaching kinetic of CaS during hydrolysis were studied intensively. Results depicted that in the H2S–H2O system, the CaS in the roasted product can be selectively and efficiently dissolved into the leachate. Furthermore, the kinetic analysis revealed that the hydrolysis of CaS conformed to the internal diffusion reaction control model in the shrinking core model and the apparent activation energy Ea = −12.02 kJ/mol. The obtained hydrolysate with low impurities could be used to capture CO2 for the production of high-purity sulfur and CaCO3. Iron and other impurities in the roasted product were concentrated into the leaching slag in the form of metallic iron and akermanite. The whole process realized the recovery of zinc, and the selective and effective extraction of calcium and sulfur, which could provide an alternative process for the large-scale treatment of these hazardous wastes.

Mining Evaluation of Sulfur Deposits in Al-Mishraq Area Using Geostatistical Method

The area of the study is located in northern Iraq on the western side opposite the confluence of the Tigris River with the upper Zab tributary, about 45 km southeast of the city of Mosul within the Hamrin-Makhoul zone belonging to the foothills zone within the unstable area. The area contains rocks of many formations ranging in age from the Lower Miocene to the Quaternary, and includes the formations of the Euphrates, Fatha, and Quaternary deposits. Sulfur deposits are present in the Fatha formation within the productive bed which contains three major sulfur-bearing horizons or zones separated by several heterogeneous layers of marly claystone and dolomite limestone of different thicknesses. The formation of sulfur due to the processes of reducing gypsum or anhydrite with the availability of hydrocarbons and the action of anaerobic bacteria, where hydrogen sulfide gas H2S is produced, which is later oxidized by groundwater, forming sulfur ore with the help of other factors represented by tectonic and hydrogeological factors.
 The mineral reserves of sulfur deposits were recalculated and estimated using the geostatistical method, as it is one of the modern applications adopted in the Rockwork-14 program, which takes into account the location of each model in relation to the other within the mineral deposits extensions and even outside the boundaries of those extensions, which gives high accuracy and reliability about the amount of reserves depending on the group Among the important criteria, such as thickness, concentration of the ore, and density, the reserve of sulfur in the Mishraq sulfur field-1 was estimated at 121,230,554,68 tons.
 The validity and suitability of using the open mine method for extracting sulfur in the study area was discussed based on a decisive and important factor, which is the stripping ratio, which determines the type of appropriate extractive method, and it was equal to 6 for the entire study area, a large value that exceeded the maximum permissible limit of 5. This method is not economically feasible due to the high extractive cost and the presence of sulfur at different depths ranging between 80-230 m as well as the presence of environmental and geological problems that hinder the use of this method in sulfur extraction.
 The study was based on the data obtained for a group of (9) exploratory wells that were drilled in the region.

Incipient metal and sulfur extraction during melting of metasomatised mantle

A long-standing debate on the genesis of magmatic-hydrothermal Cu-Au deposits is whether the elevated oxygen fugacity (fO2) and metal endowment of their parental magmas are inherited from the mantle source or acquired during fractionation within the crust. This debate is built mainly on the composition of magmas emplaced into the upper crust that underwent varying degrees of differentiation and assimilation, which inevitably obscure their relationship to mantle processes. Here, we approach this debate from a new perspective by studying melt generation directly in mantle samples. This opportunity is provided by xenoliths from Lake Bullen Merri (Australia), which record partial melting of a pre-existing metasomatic assemblage. Melting occurred when the xenoliths were incorporated in hot basalts and carried towards the surface, where quenching upon eruption froze-in the melt-restite relationships. These samples preserve patches and interconnected networks of silicate glass along grain boundaries, caught in the act of undergoing melting and melt extraction. Melting consumed mainly metasomatic hornblende, phlogopite, and clinopyroxene, generating shoshonitic compositions that can be sulfide-rich, or have negligible sulfide content. We use four independent approaches to estimate the fO2 of glass, including sulfide content, oxybarometry based on spinel-olivine pairs, Fe3+/Fetot of glass determined by synchrotron X-ray absorption near-edge structure (XANES) spectroscopy, and Cu/Fe ratio of the sulfide assemblage. Sulfide-rich melt had higher fO2 compared to the sulfide-poor melt, and these characteristics were inherited from the metasomatic assemblage; the oxidation state of the melts controlled their sulfide content. Subduction-modified mantle can thus store elevated oxidation state, sulfur, and metal content for hundreds of millions of years before low-degree partial melting generates oxidised, sulfur- and metal-enriched high-K/shoshonitic melts in post-collisional settings.

Balance experiments on the purification of waste gases of thermal power plants from SO2 and NOХ by carbonate melt

The conceptual scheme of the waste gas treatment technology of the CHP includes the organization of interconnected processes of chemical absorption of SO2 and NOx by the carbonate melt of alkali metals and further regeneration of the carbonate-sulfate melt by natural gas. In previous studies, it was shown that it is possible to purify waste gases from sulfur and regenerate the melt with carbon monoxide. The limitations of these works were the use of CO as a reducing agent during the regeneration of the melt, and the practical lack of data on the behavior of nitrogen compounds. These gaps are eliminated in this paper. Based on the results of balance experiments of the process of chemical absorption of SO2 and NOx from waste gases by a carbonate melt, and the regeneration of a carbonate-sulfate melt by natural gas, the principal possibility of implementing a closed technology for deep purification of gases from SO2 and NOx is shown. It is shown that the process of chemical absorption of gases by a carbonate melt and the regeneration of the melt by natural gas at the same temperature of 500 °C allows the technology to be implemented using a single reactor. It was found that during the chemical absorption of SO2 and NOx from the waste gases of the CHP by the carbonate melt of alkali metals, more than 95 % of sulfur and ~60 % of nitrogen compounds are captured. It is shown that in the process of regeneration of a carbonate-sulfate melt with natural gas, 100% extraction of sulfur and nitrogen into the gas phase is achieved with the formation of alkali metal carbonates in the melt. The results of the material balance of the process of chemical absorption and regeneration of the carbonatesulfate melt by reduction with natural gas are presented.

Extractive desulfurization using ethylene glycol and glycerol-based deep eutectic solvents: engineering aspects and intensification using ultrasound

In the present study, three deep eutectic solvents (DESs), namely TBAB:2EG, TPAB:3EG, and TPAB:2G, were synthesized by using hydrogen-bond acceptors (HBAs) (tetrabutylammonium bromide (TBAB), tetrapropylammonium bromide (TPAB)), and hydrogen-bond donors (HBDs) (ethylene glycol (EG), glycerol (G)). These DESs formed eutectic points at HBA:HBD molar ratios of 1:2, 1:3, and 1:2, respectively. The prepared DESs were analyzed by FTIR, and their structures were confirmed through 1H-NMR. The performance of the prepared DES was evaluated in terms of distribution coefficient, selectivity, performance index, and capacity of solvents for extractive desulfurization. Maximum extraction efficiencies of 81%, 77%, and 72% were obtained with TBAB:2EG, TPAB:3EG, and TPAB:2G, respectively, with optimized parameters but without the use of ultrasound. The extractive desulfurization was intensified using ultrasound that enhanced the mass transfer between the two phases. Individual and overall mass transfer coefficients in the fuel and solvent phases with and without ultrasound have been determined. The intensified extraction indicates the positive effect of the US on the DBT extraction by DES. The decrease in efficiency due to prolonged use of the DES was regained after regeneration. The thermodynamic parameters of the sulfur extraction process have also been calculated.

Sulfonation Reactions behind the Fate of White Wine's Shelf-Life.

White wine’s oxidative stability after several years of bottle aging is synonymous to its organoleptic quality. In order to gain control over the cascade of chemical reactions that are implicated in that phenomenon, fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS)-based metabolomics and sensory evaluation were combined for the analysis of a vertical series of white wines from different vineyard plots. Data mining using supervised cluster analysis allowed the extraction of known and unknown sulfur- and nitrogen-containing molecular features, with oxidative stability molecular markers presenting an increased number of S and O atoms in their formulas. In their majority, S-containing molecular features possessed between 4 to ~12 O atoms, indicating the relatively higher importance of sulfonation reactions as opposed to dimerization reactions. Molecular networking, based on sulfonation reaction transformations, evidences the importance of hitherto unknown and/or minor sulfur dioxide binders (peptides, aldehydes, and polyphenols) on wine’s oxidative stability.

Recovery of Zinc, and Extraction of Calcium and Sulfur from Zinc-Rich Gypsum Residue by Selective Reduction Roasting Combined with Hydrolysis Process

Recovery of Zinc, and Extraction of Calcium and Sulfur from Zinc-Rich Gypsum Residue by Selective Reduction Roasting Combined with Hydrolysis Process

Simultaneous Extraction of Sulfur and Nitrogen Compounds from Model Diesel Fuel Using Neoteric Green Solvents.

Removal of nitrogen and sulfur compounds from diesel fuel is essential to comply with the increasing stringent regulations. The extraction capability of two deep eutectic solvents, namely, tetrabutylphosphoniumbromide/ethylene glycol, TBPBr/EG, with molar ratio 1:2, and tetrabutylammoniumbromide/ethylene glycol, TBABr/EG, with molar ratio 1:2, in simultaneously extracting basic nitrogen, nonbasic nitrogen, and sulfur compounds represented by pyridine, indoline, and dibenzothiophene (DBT) from n-hexadecane, was investigated. Two pseudo-ternary phase diagrams of (TBPBr/EG + (pyridine + indoline + DBT) + n-hexadecane) and (TBABr/EG + (pyridine + indoline + DBT) + n-hexadecane) were predicted via a conductor-like screening model for real solvents (COSMO-RS) and experimentally validated at 298.15 K and 1 atm. Both solvents showed zero cross-contamination, indicating the suitability of all solvents as extraction solvents. The tie lines obtained for both COSMO-RS and experiments were in agreement and had root-mean-square deviation (RMSD) values of less than 5% for both systems. Selectivity and distribution ratio calculated indicates the suitability of both solvents in extracting sulfur and nitrogen compounds from hexadecane. Two new parameters, namely, extraction efficiency, α, and extraction affinity, β, were introduced to ease the performance comparison of both solvents. TBPBr/EG shows a slightly better performance than TBABr/EG. Other than that, the presence of multiple solutes shows low effects on the performance of these solvents.

Synthesis, Characterization and Application of Trihexyl (Tetradecyl) Phosphonium Bromide as a Promising Solvent for Sulfur Extraction from Liquid Fuels

Sulfur reduction from fuels is an essential assignment to perform for environmentally friendly rules and a petroleum refining perspective. Extractive desulfurization is a unique and promising technique to attain prerequisites of legislative S-content (EURO VI/Bharat VI of S < 10 ppm). Phosphonium ionic liquids are competent for S-extraction, because of their pleasing green features and high production rate, compared to imidazolium ionic liquids. The findings of this research confirmed that trihexyl (tetradecyl) phosphonium bromide [THTDP]Br appeared as an alluring solvent for S-removal. The Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), ultraviolet (UV), X-ray diffraction (XRD), thermogravimetry/differential scanning calorimetry (TG/DSC), and electron paramagnetic resonance (EPR) analysis were discussed, with regard to molecular confirmations and compound purity. Furthermore, [THTDP]Br physical properties were explored thoroughly. The influence of various parameters, viz. temperature, S-compounds, shaking time, and [THDTP]Br recycling, was systematically presented. In extractive desulfurization, 88.5% dibenzothiophene removal was achieved with a mass ratio of ionic liquid to fuel of 1:1 in 30 min at 30 °C. Density functional theory (DFT) calculations are conducted to probe the overlapping of molecular orbitals between [THTDP]Br and various S-compounds. The energy band gap of [THTDP]Br and DBT is −5.74 eV and is found to be the lowest among the complexes. Without a significant S-reduction, [THTDP]Br reclaimed up to 10 cycles. Also, S-removal from gasoline and diesel with multistage extraction was examined. This research provided noteworthy understandings of phosphonium ILs as efficient extractants for extractive desulfurization.

Removing Simultaneously Sulfur and Nitrogen from Fuel under a Sustainable Oxidative Catalytic System

An effective process to remove nitrogen-based compounds from fossil fuels without harming the process of sulfur removal is an actual gap in refineries. A success combination of desulfurization and denitrogenation processes capable of completely removing the most environmental contaminates in diesel under sustainable conditions was achieved in this work, applying polyoxometalates as catalysts, hydrogen peroxide as oxidant, and an immiscible ionic liquid as an extraction solvent. The developed process based in simultaneous oxidative desulfurization (ODS) and oxidative denitrogenation (ODN) involved initial extraction of sulfur and nitrogen compounds followed by catalytic oxidation. Keggin-type polyoxomolybdates revealed much higher reusing capacity than the related polyoxotungstate. Effectively, the first catalysts practically allowed complete sulfur and nitrogen removal only in 1 h of reaction and for ten consecutive cycles, maintaining the original catalyst and ionic liquid samples.

Flue gas purification from SO2 and NOx using molten mixture of alkali metal carbonates

ABSTRACT Sulfur dioxide (SO2) and nitrogen oxides (NOx) in flue gas are a hazardous atmospheric pollutant associated with coal combustion and non-ferrous metal production. Here we report that laboratory pilot unit for scrubbing of industrial flue gas containing 80 ± 2 ppm SO2 followed by melt regeneration with either CO or natural gas, verified that only 1.5–2.0 ppm SO2 remained in the flue gas. The tests with the semi-industrial scale unit (271.26 kg of the eutectic carbonate melt and flue gas containing 0.15% SO2, 13 ppm NO, 52 ppm NO2) were received. In all tests, sulfur extraction from flue gas to the carbonate melt was >90–95% and nitrogen oxides extraction from flue gas to the carbonate melt was 60%. Sulfur and nitrogen oxides extraction from carbonate–sulfate–nitrite melt during regeneration stage was >99%. Carbonate melt-based SO2 scrubbing therefore represents a practical and economical method for limiting sulfur and NOx emission to the atmosphere from both coal-firing power stations and non-ferrous metallurgical processing plants.

Improved extraction of acid-insoluble monosulfide minerals by stannous chloride reduction and its application to the separation of mono- and disulfide minerals in the presence of ferric iron

Metal sulfides, which are important indicators of sulfur cycling, are usually divided into two categories according to sulfur chemical valence: (1) monosulfides (S2−) and (2) disulfides (S22−). The two sulfur species are separated and quantified by a sequential-extraction method. Specifically, monosulfides are extracted as acid-volatile sulfide (AVS) using 6 M HCl prior to the extraction of disulfides using acidic CrCl2, which is defined as chromium-reducible sulfur (CRS). However, the conventional AVS procedure does not result in the quantitative extraction of S2− from the acid-insoluble metal monosulfide, copper sulfide (CuS). Consequently, residual sulfur in CuS (CuS-S) may be extracted as CRS resulting in the inaccurate separation of these two sulfur species. In this study, we used stannous chloride (SnCl2) to improve CuS-S recovery in the AVS procedure and permit the separate extraction of sulfur from CuS and pyrite (FeS2), the most abundant disulfide in nature. Our results show that the addition of SnCl2 increased the recovery of CuS-S as AVS from less than 36% to as high as 92% in the absence of pyrite and Fe3+ and 89% in the presence of pyrite and Fe3+. In addition, based on the observed correlation between the concentration of SnCl2 and the dissolution of FeS2, we identified the appropriate concentration of SnCl2 needed to avoid the dissolution of FeS2 in the AVS procedure. SnCl2 also minimized the oxidation of CuS-S by Fe3+ released from ferric minerals during the extraction of AVS. Based on the results of a series of sequential-extraction experiments, we show that an amendment of SnCl2 in the AVS procedure followed by CRS permits the quantitative separation of CuS-S and FeS2-S while also preventing interference by Fe3+. Our method will find application in research concerned with the fate of metals and the biogeochemistry of sulfur in the environment.

Novel phenolic deep eutectic solvents for desulfurisation of petrodiesel

In this work, a novel production of “deep eutectic solvents (DESs)” has been utilised for the elimination of sulfur composition, particularly from crude oil by liquid-liquid extraction. Herein, we present the first demonstration of the use of novel DESs formed by phenol, catechol, resorcinol and o-cresol as “hydrogen bond donors (HBDs)” with trimethyl hydroxyammonium chloride (ChCl) as the hydrogen bond acceptor to affect the efficient separation of organosulfur compounds from diesel. These DES electrolytes have been applied for the sulfur extraction from Iraqi real diesel fuel as determined using X-ray florescence sulfur measurements. The optimisation condition factors in this research have been studied, containing reaction time, the temperature of extraction process, the ratio of mass of diesel to DES and regeneration of DESs. The results indicated that phenol-based DESs extracted more than 38% of S-compounds from true diesel fuel when the mass ratio DES:fuel was 1:2 at 55 °C. Anhydrous ferric chloride (FeCl3) was also utilised as a catalyst in this work, where it was demonstrated that charge-dipole interaction between the DES and sulfide compounds was the key driving force behind the desulfurization process. We have shown that the extraction efficiency could be summarised as o-cresol + ChCl < catechol + ChCl < resorcinol + ChCl < phenol + ChCl. More than 44% of sulfur species could be removed when a 1:1:1 molar ratio of ChCl: phenol: acetic acid was utilised with H2O2 as an oxidant.