Sulfation Reaction Research Articles

Performance of Compressed Stabilized Earth Blocks in sulphated medium

Sulphates are considered as the most known chemical compounds that tend to induce problems in building materials containing calcium-based binders. This work studies the impact of sulphates on the behavior of Compressed Stabilized Earth Blocks (CSEB) produced from two soils of different grain size distributions and stabilized with different binders including cements CEM II, CEM I resistant to sulphates and lime. Two different presses were used to manufacture the blocks. The performance of the material was examined based on the evolution of the compressive strength and the blocks weight aspect after chemical cure involving sulphates. The results show that the action of sulphates on CSEB is mostly governed by the nature of the base soil, but depends also on the type of treatment and on the level of compaction. Sulphate reaction products namely ettringite and gypsum have a deleterious action on the CSEB compressive strength and on their mass as much as the base soil contains fine particles, and would be less disruptive when the soil is of coarse nature. The utilization of a cement CEM I resistant to sulphates could moderate the damage effects of sulphates on the blocks, but its effectiveness is noticeable only on the coarse soil; on the fine soil, this type of cement is not effective. On the other hand, the subsequent expansion related to the formation of sulphate reaction products (ettringite & gypsum) is more constraining when the block density is higher, and exerts lower pressure when the blocks are porous.

Preparation of 2,5-diamino-1,3,4-thiadiazole derivatives using MgO nanoparticles as heterogeneous basic catalysts

The synthesis of 2,5-diamino-1,3,4-thiadiazole derivatives was performed via the reaction of dithiocarbamate derivatives and hydrazine sulfate in presence of MgO nanoparticles as heterogeneous catalysts, which were prepared by the sol–gel method. The pure products were produced in a simple and clean method in presence of MgO nanoparticles (5 mg) in the refluxing water (0.5 cm3) around 10 h with good-to-excellent yields (up to 95%). The prepared metal oxide nanoparticles were characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, and Fourier transform infrared spectroscopy.

Serotransferrin and C-type lectin could mediated NCC activity by interacting with NCCRP-1 in Nile tilapia (Oreochromis niloticus)

The alumina nanoparticles (Al2O3 NPs) prepared by sol-gel method by reaction of aluminum sulfate with ammonia was tested for their adsorption capacity in the extraction of pesticide residues in water. The synthesized nanoparticles (NPs) size was determined by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The surface morphology of NPs was described by Scanning Electron Microscope (SEM). The cartridges of solid phase extraction (SPE) were prepared by Al2O3 NPs and protected between two polytetrafluoroethylene (PTFE) frits. These cartridges are used in extraction of different types of pesticide residues (ametryn, prometryn, simazine, and simetryn) in water. The water samples were spiked and passed through the cartridges with aliquots of pesticides. Testing of the amounts of pesticides adsorbed on the cartridges. The impact of temperature, sample quantity, flow rate, pH and ionic strength on cartridge performance was verified. Results of fortified sample assessment were contrasted with information collected from commercially accessible C18 cartridges for sample volume. The Liquid Chromatography Electrospray Ionization Tandem Mass Spectroscopy (LC-ESI-MS/MS) method involves the simultaneous determination of four herbicides in multiple reactions monitoring (MRM) mode and the detection limit is 0.005–0.025 μg/mL and the quantification limit is 0.01 μg/mL.

Interfacial-engineered cobalt@carbon hybrids for synergistically boosted evolution of sulfate radicals toward green oxidation

Efficient water remediation relies on robust and capable catalysts to drive the cutting-edge purification technologies. In this work, Prussian blue analogues (PBA) are engaged as the starting materials to fabricate various transition metal (TM)@carbon composites for water decontamination. The encapsulated metallic cobalt is unveiled to be more favorable to deliver electrons to the adjacent carbons than CoP and Co3O4, due to the low work function, high conductivity and formation of multiple Co-C bonds for electron tunnelling. Such a hybrid structure significantly tailors the electron density of the carbon lattice, which is the decisive factor influencing activating peroxymonosulfate (PMS) to generate highly reactive sulfate radicals for degradation of contaminants, meanwhile achieving outstanding long-term stability. Deliberate material design and theoretical computations unveil the structure-activity regimes of the composite materials in promoted carbocatalysis. This proof-of-concept study dedicates to elucidating the principles in developing fine-tuned and high-performance TM@carbon hybrids for advanced catalytic oxidation.

Fundamental study of heterogeneous KCl sulfation under oxy‐fuel combustion conditions

Under oxy-fuel combustion condition, SO2 in the flue gas would be accumulated by recirculation, which is conducive to the heterogeneous sulfation reaction of alkali metals. In the present study, experiments were conducted in a fixed bed to investigate the effects of operating parameters and mineral additives (SiO2, CaO, and Fe2O3) on the heterogeneous sulfation of potassium chloride under oxy-fuel combustion atmosphere. According to the results here, the heterogeneous sulfation reaction was a kinetically controlled process, with the activation energy of 93.6 kJ/mol. The reaction orders with respect to SO2, O2, and H2O were determined as 1, 0.6 and 0 (H2O involved in the reaction). While the reaction would be promoted obviously in the absence of H2O. The rate law of heterogeneous sulfation of potassium chloride was derived based on the experimental data. Compared with air combustion, the heterogeneous sulfation rate was lower under oxy-fuel combustion. All the mineral additives employed would affect the sulfation reaction. The sulfation reaction can be catalyzed by Fe2O3. While CaO would suppress the reaction by competing for SO2 with KCl. The reaction between CaO and SO2 could also be catalyzed by Fe2O3. Besides, SO2 was more reactive towards CaO than KCl.

Sulfate and hydroxyl radicals-initiated degradation reaction on phenolic contaminants in the aqueous phase: Mechanisms, kinetics and toxicity assessment

Phenolic organic contaminants (POCs) in water environment have been usually degraded by advanced oxidation processes (AOPs) based on sulfate radicals (SO4·-) and hydroxyl radicals (OH). In this paper, the first step of SO4·-/·OH-initiated oxidation reactions toward 19 POCs were investigated using density functional theory (DFT) in order to explore and compare the reactivity of POCs with two free radicals in the aqueous phase. The oxidation reactions initiated by SO4·-/·OH were confirmed that POCs can follow three reaction mechanisms: radical adduct formation (RAF), hydrogen atom abstraction (HAA), and single electron transfer (SET). The rate constants of all primary oxidation reactions were calculated using transition state theory (TST). The results turn out that the stronger the electron donating effects of the substituent on POCs, the better the reactivity of POCs with two free radicals. SET mechanisms are main reaction pathways for SO4·--initiated oxidation reactions. Furthermore, the ecotoxicity assessment shows that most OH adducts have higher toxic on aquatic organisms than corresponding reactants. For all the POCs covering in this work, the order of acute toxicity is p-DP > o-AP > m-AP (p-AP) > MP > CP > NP > m-DP (o-DP) > phenol > YP, while the chronic toxicity is in the order p-DP > o-AP > m-AP (p-AP) > MP > CP > NP > YP > phenol > m-DP (o-DP). Thus, the application of AOPs for the removal of POCs should be taken seriously.

Melting Down Protein Stability: PAPS Synthase 2 in Patients and in a Cellular Environment.

Within the crowded and complex environment of the cell, a protein experiences stabilizing excluded-volume effects and destabilizing quinary interactions with other proteins. Which of these prevail, needs to be determined on a case-by-case basis. PAPS synthases are dimeric and bifunctional enzymes, providing activated sulfate in the form of 3′-phosphoadenosine-5′-phosphosulfate (PAPS) for sulfation reactions. The human PAPS synthases PAPSS1 and PAPSS2 differ significantly in their protein stability as PAPSS2 is a naturally fragile protein. PAPS synthases bind a series of nucleotide ligands and some of them markedly stabilize these proteins. PAPS synthases are of biomedical relevance as destabilizing point mutations give rise to several pathologies. Genetic defects in PAPSS2 have been linked to bone and cartilage malformations as well as a steroid sulfation defect. All this makes PAPS synthases ideal to study protein unfolding, ligand binding, and the stabilizing and destabilizing factors in their cellular environment. This review provides an overview on current concepts of protein folding and stability and links this with our current understanding of the different disease mechanisms of PAPSS2-related pathologies with perspectives for future research and application.

UPLC-Q-TOF-MS/MS analysis on prototypes components and metabolites of effective fractions of Polygonum orientale flower in rat serum and urine

Ultra performance liquid chromatography coupled with time-of-flight mass spectrometry( UPLC-Q-TOF-MS/MS) method was applied to analyze the prototypes and metabolites of the effective components of Polygonum orientale in SD rat serum and urine. The separation was performed on Agilent Eclipse Plus C_(18) column( 2. 1 mm×100 mm,1. 8 μm),with 0. 1% formic acid solution( A)-acetonitrile( B) as the mobile phase for gradient elution. Mass spectrometry data of biological samples were obtained under positive and negative electrospray ion mode. By comparing chromatogram differences between blank samples and drug treatment samples,prototype components and metabolites of the effective components of P. orientale extract were identified. The results showed that 12 metabolites were detected in serum and 26 metabolites in urine( including cross-components) of rats. The main metabolic pathways included hydrogenation,hydroxylation,glucuronidation,sulfation reaction,and methylation-glucuronidation,etc. The method established in this study was reliable and effective for studying the metabolic characteristics of the effective components of P. orientale in rats,and it can provide a reference for further studies on therapeutic material basis of this herb.

Towards computational prediction of the heparan sulfate interactome

Glycosaminoglycans (GAGs), are linear polysaccharides with repeating disaccharide units. GAGs interact with numerous proteins to regulate various physiological and pathological processes such as hemostasis, cell adhesion, growth factor signaling, coagulation, viral invasion and protease regulation. Heparin (H) and heparan sulfate (HS), members of the GAG superfamily, are composed of alternating glucosamine (GlcNp) and uronic acid (UAp) residues (either glucuronic acid (GlcAp) or iduronic acid (IdoAp)) linked by 1→4 linkage that are incompletely modified through sulfation, acetylation and epimerization reactions. These modifications can produce 48 distinct disaccharides, of which 23 have been found in nature to date. Further, the IdoAp residue can exist in multiple conformations, especially 1C4 and 2SO, which can interconvert easily in solution to enhance structural possibilities. Thus, combinatorial arrangements of the several configurational and conformational variations possible at the monosaccharide level generate millions of distinct HS sequences. Yet, only one sequence, i.e., the heparin pentasaccharide sequence that binds to antithrombin with high affinity, has found therapeutic application. Surely, a number of HS sequences bind to proteins and modulate their functions. To date, these interactions have been studied in silos, which has led to rather poor understanding of HS interactome.Elucidating the HS interactome is challenging. An analysis of gene sequences has led to prediction that 435 human proteins could interact with heparin. Yet, whether these are specific, and therefore physiologically relevant, remains to be understood. We have developed a computational strategy called Combinatorial Virtual Library Screening (CVLS) to identify sequences that display a high level of specificity in binding to protein targets. The CVLS algorithm uses a two‐step approach in which in silico ‘affinity’ and in silico ‘specificity’ of interaction are key drivers of analysis. The CVLS algorithm utilizes all possible GAG sequences binding to the predicted site of GAG binding on target proteins to identify the sequence with highest specificity for each target protein. We have now validated the application of the CVLS algorithm for understanding GAG recognition of several proteins including antithrombin (AT), heparin cofactor II (HCII), fibroblast growth factor‐2 & its receptor (FGF‐2/FGFR1), transforming growth factor β2 (TGFβ2), thrombin, histone acetyltransferase p300, chemokine CXCL13 and human neutrophil elastase. We expect that our CVLS tool, which can help experimental biologists in identifying the key GAG sequence(s) to study, will be especially useful in elucidating the HS interactome.Support or Funding InformationNIH grant HL107152 to URD. Computational facility provided by National Center for Research Resources to Virginia Commonwealth University through grant S10 RR027411.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Synthesis, characterization and rare earth elements adsorption properties of phosphonate metal organic frameworks

The architectural structures of MOFs provide special properties as high thermal and mechanical stability, high surface areas and large pore sizes with potential applications in diverse areas. Rare Earth Elements (REEs) are widely used in the various disciplines: luminescent compounds, catalysis, coordination chemistry, solid state chemistry, organometallic compounds, and environmental chemistry. For environmental protection, the elimination of toxic metals from wastewaters previously releasing into the environment are required. Phosphonate MOFs were obtained in our labs by the reaction of divalent inorganic sulphates with phosphonoacetic acid (Cp) or styrylphosphonic (Sp) in hydrothermal conditions and characterized by FTIR and TGA.The phosphonate MOFs were used in the removal process of Cs(I) and Tl(I) ions from aqueous solutions done in batch mode, varying the initial concentration of the metal ions, keeping for all the samples a solid:liquid ratio of 1 g/L. From the experimental data were observed that the adsorption capacity developed by the studied materials increase in the following order: CuCp < CoCp < CoSp, both for the removal of Cs(I) ions and also for the elimination of Tl(I) ions. The adsorption kinetics was better described by pseudo-second-order kinetic model compare to pseudo-first-order model. The experimental data showed good fit to the Langmuir isotherm.

Phase diagrams of the quaternary system K+, NH4+//Cl−, SO42−-H2O at 273.15 K and their application

In order to produce chloride-free K-N compound fertilizers by the reaction of KCl (carnallite) and (NH4)2SO4 as raw materials, the phase equilibrium of the mutual quaternary system K+, NH4+//Cl−, SO42−-H2O and its two ternary subsystems KCl-NH4Cl-H2O, K2SO4-(NH4)2SO4-H2O were measured by isothermal method at 273.15 K. And the corresponding phase diagrams were plotted and analysed. The equilibrium phase diagram of the quaternary system K+, NH4+//Cl−, SO42−-H2O shows that there is one saturation point and three solid phase fields of crystallization. Three fields of crystallization represent solid solution salts corresponding to (K1−t, (NH4)t)2SO4, (K1−m, (NH4)m)Cl and ((NH4)n, K1−n)Cl respectively. The phase analysis shows that field of (K1−t, (NH4)t)2SO4 is larger than other crystalline fields, and there is no crystalline field of pure potassium sulfate, which indicates that the K1-t, (NH4)t)2SO4 is easy to crystallize out from solution. By analysing and calculating the phase diagrams of K+, NH4+//Cl−, SO42−-H2O at 273.15 K and 323.15 K, chloride-free K-N compound fertilizers (K1−t, (NH4)t)2SO4) can be obtained using KCl and (NH4)2SO4 as raw materials at 273.15 K, and ((NH4)t, K1−t)Cl can crystallize out at 323.15 K. The new technology shows the advantages of effective utilization of carnallite resources. The research on this quaternary phase diagram is the foundation of the chloride-free potash production by the reaction of carnallite and ammonium sulfate.

Synthesis of magnetite-supported catalysts for phenol oxidation in aqueous solution

One of the usual ways to degrade phenol contaminant is sulfate radical-based advanced oxidation processes (SR-AOPs). In this study, reactive sulfate radicals have been produced by Co3O4/Fe3O4@nSiO2@mSiO2 catalyst and Fe3O4 nanoparticles. It has been found that the couple of supported cobalt catalyst and peroxymonosulfate (PMS) is highly effective to produce sulfate radicals for phenol oxidation. In contrary to, Fe3O4-PMS system displays much low phenol degradation, and Co3O4/Fe3O4@nSiO2@mSiO2 catalyst shows a good catalytic performance in solution. The properties of this supported catalyst have been characterized by XRD (powder X-ray diffraction), SEM–EDS (scanning electron microscopy–energy-dispersive X-ray spectroscopy), TEM (transmission electron microscopy), and nitrogen adsorption–desorption. This magnetic catalyst is facility separated from the medium by an external magnetic field. Finally, three different methods involving annealing in the air, washing with water and applying ultrasonics was used for regenerating the deactivated catalyst. The heat treatment can recover the catalyst nearly.

Identification of the absorbed components and their metabolites of Tianma-Gouteng granule in rat plasma and bile using ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry.

Tianma-Gouteng granule (TGG), a Chinese herbal formula preparation, is clinically used for the treatment of cardio-cerebrovascular diseases such as hypertension, cerebral ischaemia, acute ischaemic stroke and Parkinson's disease. Although few reports have been published concerning the absorbed prototype components of TGG, the possible metabolic pathways of TGG in vivo remain largely unclear. In this study, a method using UPLC-Q/TOF MS was established for the detection and identification of the absorbed prototype components and related metabolites in rat plasma and bile after oral administration of TGG at high and normal clinical dosages. A total of 68 components were identified or tentatively identified in plasma and bile samples, including absorbed prototypes and their metabolites. The major absorbed components were gastrodin, isorhynchophylline, rhynchophylline, isocorynoxeine, corynoxeine, geissoschizine methyl ether baicalin, baicalein, wogonoside, wogonin, geniposidic acid, leonurine, 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside and emodin. The main metabolic pathways of these components involved phase I (isomerization, hydrolysis and reduction) and phase II (glucuronidation and sulfation) reaction, and the phase II biotransformation pathway was predominant. The present study provides rich information on the in vivo absorption and metabolism of TGG, and the results will be helpful for further studies on the pharmacokinetics and pharmacodynamics of TGG.

The combined effect of H2O and SO2 on the simultaneous calcination/sulfation reaction in CFBs

The combined effect of H2O and SO2 on the reaction kinetics and pore structure of limestone during simultaneous calcination/sulfation reactions under circulating fluidized bed (CFB) conditions was first studied in a constant‐temperature reactor. H2O can accelerate the sulfation reaction rate in the slow‐sulfation stage significantly but has a smaller effect in the fast‐sulfation stage. H2O can also accelerate the calcination of CaCO3, and should be considered as a catalyst, as the activation energy for the calcination reaction was lower in the presence of H2O. When the limestone particles are calcining, SO2 in the flue gas can react with CaO on the outer particle layer and the resulting CaSO4 blocks the CaO pores, increases the diffusion resistance of CO2, and, in consequence, decreases the calcination rate of CaCO3. Here, gases containing 15% H2O and 0.3% SO2 are shown to increase the calcination rate. This means that the accelerating effect of 15% H2O on CaCO3 decomposition is stronger than the impeding effect caused by 0.3% SO2. The calcination rate of limestone particles was controlled by both the intrinsic reaction and the CO2 diffusion rate in the pores, but the intrinsic reaction rate played a major role as indicated by the effectiveness factors determined in this work. This may explain the synergic effect of H2O and SO2 on CaCO3 decomposition observed here. Finally, the effect of H2O and SO2 on sulfur capture in a 600 MWe CFB boiler burning petroleum coke is also analyzed. The sulfation performance of limestone evaluated by simultaneous calcination/sulfation is shown to be much higher than that by sulfation of CaO. Based on our calculations, a novel use of the wet flue gas recycle method was put forward to improve the sulfur capture performance for high‐sulfur low‐moisture fuels such as petroleum coke. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1256–1268, 2019

Re-evaluation of sulfate radical based–advanced oxidation processes (SR-AOPs) for treatment of raw municipal landfill leachate

Sulfate radical (SO4-) -based advanced oxidation processes (SR-AOPs) have proven effective for simultaneously removing refractory dissolved organic matter (DOM) and ammonia in municipal landfill leachates. However, the knowledge on the competition of leachate DOM and ammonia for SO4-, the utilization efficiency of persulfate, as well as the reaction pathways and final products of ammonia oxidation during the SR-AOP treatment remains little known, thereby leading to a lack of a comprehensive evaluation of the emerging leachate treatment technology. The objective of this study was to further investigate the performance of a thermally activated persulfate system for treatment of a mature landfill leachate and re-evaluate the benefits and restrictions of SR-AOPs for leachate treatment. The laboratory experimental results showed that removal patterns of chemical oxygen demand (COD) and ammonia relied heavily upon the dose of persulfate that could be thermally activated to produce reactive sulfate radicals, reflecting the competition of leachate DOM, ammonia, and non-target leachate constituents for SO4-. The utilization efficiency of the added persulfate could be more efficiently utilized for removing the two target leachate pollutants at a lower persulfate dose, whereas more persulfate was wasted due to the reactions with non-target leachate constituents (e.g. Cl− and CO32−) and/or self-decomposition with the increasing persulfate dose. During the treatment, ammonia was oxidized, via the direct attack of SO4- and/or by molecular chlorine produced from the reactions of chloride and sulfate radicals, into nitrate and nitrogen gas, while nitrite was not detected. Of importance, this study highlighted three potentially negative impacts of SR-AOPs on the quality of treated leachate, including accumulation of total dissolved solids, the production of undesirable nitrate, and the pH decrease due to the continuous formation of hydrochloric acid. Therefore, the three issues should be carefully evaluated when a SR-AOP is selected for leachate treatment. Because these impacts become less pronounced with a decreasing persulfate dose, SR-AOPs as a pre-treatment, which is achieved at a relatively low persulfate dose, may be an appropriate option for the SR-AOP application to leachate treatment.

Evaluation of damage in concrete from structures affected by internal swelling reactions – A case study

Nowadays, a significant number of concrete infrastructures are affected by internal swelling reactions (ISR). The most common in Portugal are the alkali-silica reaction (ASR) and the internal sulphate reaction (DEF). Existing knowledge does not allow for a complete assessment of the actual condition of an ISR-affected structure and an accurate prediction of the mechanical properties deterioration and, consequently, of the period during which the structure will effectively perform its function. To help surpassing this situation, research is being conducted at LNEC to contribute to the establishment of a method for a more accurate determination of the current level of ISR progression and of the deterioration of the concrete mechanical properties. This paper aims at contributing to the ongoing discussion of this topic and, therefore, presents the methodology followed to assess the condition of the concrete from an ISR-affected motorway underpass in Portugal. It includes a comprehensive experimental campaign, performed to concrete cores, to allow for an adequate diagnosis and prognosis of the ISR development. The results evidenced the utility of such a methodology on the appraisal of the actual expansion level attained to date in concrete from ISR-affected structures.

Alteration of solid bitumen by hydrothermal heating and thermochemical sulfate reduction in the Ediacaran and Cambrian dolomite reservoirs in the Central Sichuan Basin, SW China

Solid bitumen in reservoir rocks is an allochthonous organic matter formed from bitumen or liquid hydrocarbons by various alteration processes. In this study, two types of altered solid bitumen have been identified in both the Ediacaran Dengying and Cambrian Longwangmiao formations in the Central Sichuan Basin using petrographic, microthermometric, chemical, and isotopic data. The hydrothermally altered bitumen (type 1) is associated with the pore-filling saddle dolomite and quartz in which homogenization temperatures of some fluid inclusions are more than 10 °C higher than the maximum burial temperature of the Dengying Formation. It has various anisotropic textures with significantly high bireflectance values (Rbmax − Rbmin, %) between 3.89% and 9.21%. Moreover, the hydrothermal alteration led to 13C-enrichment in the type 1 bitumen compared to the normally matured bitumen derived from the same source. On the other hand, the thermochemical sulfate reduction (TSR)-altered bitumen (type 2) has S/C atomic ratios of up to approximately 0.06. The δ34S values of type 2 bitumen are close to those of the carbonate-associated sulfate and similar to the TSR-derived H2S in the same reservoirs. A strong negative correlation exists between S/C atomic ratios and δ13C values in the type 2 bitumen in the Dengying Formation, which is interpreted as a result of an increasing incorporation of the 13C-depleted ethanethiol into the bitumen during TSR. This interpretation is consistent with the fact that the remaining ethane became isotopically heavier as TSR proceeded. In addition, the reactive sulfate for TSR was primarily derived from the hydrothermal sulfate, such as barite. This is evidenced by the replacement of hydrothermal barite by the 34S-enriched pyrite and the small differences in δ34S value between the barite and the type 2 bitumen (or the TSR-derived H2S) in the same strata. We suggest that TSR in the Ediacaran and Cambrian hydrocarbon reservoirs was probably initiated by hydrothermal activity.

An experimental study of SO2 reactions with silicate glasses and supercooled melts in the system anorthite–diopside–albite at high temperature

Sulfur dioxide [SO2(g)] is the most abundant sulfur-bearing volcanic gas species on Earth. From its magmatic origin at depth to expulsion at the surface via either persistent degassing or large explosive volcanic eruptions, SO2(g) interacts with silicate materials at elevated temperatures. Similar high-temperature reactions also occur in the volcanic systems and the atmospheres of Venus, the Galilean moon Io, and in Mars’ past, as well in industrial flue-gas processing. We present an experimental investigation of the reaction between SO2(g), glasses and supercooled melts in the system anorthite–diopside–albite (CaAl2Si2O8–CaMgSi2O6–NaAlSi3O8). The samples were exposed to SO2(g) at 600–800 °C for experimental durations of 10 min to 24 h. The reactions resulted in the formation of sulfate coatings and modified the near-surface composition of the silicate samples. The predominant sulfate reaction product is CaSO4, with hydrated MgSO4 or Na2SO4 also observed in some experiments. In the anorthite–diopside system, the reaction extent strongly depends on the temperature relative to the glass transition temperature (Tg). Above Tg, in reactions with supercooled melts, the reaction forms up to 20 times more sulfate. The overall rate of sulfate formation is controlled by the diffusive flux of Ca, Mg and Na from the increasingly depleted silicate to the surface where the reaction with SO2(g) occurs. The sulfate-forming reaction results in a volume increase relative to the unreacted silicate. When this reaction occurs in the subvolcanic environment it causes an increased molar volume that may close veins, reducing the permeability and decrease the SO2(g) flux at the surface. An increase in the SO2(g) flux would then result in the opening of new veins, which may be accompanied by seismic activity. Additionally, the change in molar volume may itself trigger seismicity. The strong preferential uptake of Ca into the sulfate reaction product results in a Si- and Al-enriched silicate. In the sulfate, the Ca component may be mobilized by secondary processes such as through the interaction with meteoric fluids. We recommend that the products of such gas–solid reactions should be the object of remote and robotic investigations of planetary environments with volcanic histories such as on Mars, Io, Venus and Mercury.

Synthesis of steroid bisglucuronide and sulfate glucuronide reference materials: Unearthing neglected treasures of steroid metabolism

Doubly or bisconjugated steroid metabolites have long been known as minor components of the steroid profile that have traditionally been studied by laborious and indirect fractionation, hydrolysis and gas chromatography-mass spectrometry (GC–MS) analysis. Recently, the synthesis and characterisation of steroid bis(sulfate) (aka disulfate or bis-sulfate) reference materials enabled the liquid chromatography-tandem mass spectrometry (LC–MS/MS) study of this metabolite class and the development of a constant ion loss (CIL) scan method for the direct and untargeted detection of steroid bis(sulfate) metabolites. Methods for the direct LC–MS/MS detection of other bisconjugated steroids, such as steroid bisglucuronide and mixed steroid sulfate glucuronide metabolites, have great potential to reveal a more complete picture of the steroid profile. However, access to steroid bisglucuronide or sulfate glucuronide reference materials necessary for LC–MS/MS method development, metabolite identification or quantification is severely limited. In this work, ten steroid bisglucuronide and ten steroid sulfate glucuronide reference materials were synthesised through an ordered combination of chemical sulfation and/or enzymatic glucuronylation reactions. All compounds were purified and characterised using NMR and MS methods. Chemistry for the preparation of stable isotope labelled steroid {13C6}-glucuronide internal standards has also been developed and applied to the preparation of two selectively mono-labelled steroid bisglucuronide reference materials used to characterise more completely MS fragmentation pathways. The electrospray ionisation and fragmentation of the bisconjugated steroid reference materials has been studied. Preliminary targeted ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis of the reference materials prepared revealed the presence of three steroid sulfate glucuronides as endogenous human urinary metabolites.

Effect of chlorine, sulfur, moisture and ash content on the partitioning of As, Cr, Cu, Mn, Ni and Pb during bituminous coal and pickling sludge co-combustion

The effect of chlorine, sulfur, moisture and ash content in blended fuels on the partitioning of As, Cr, Cu, Mn, Ni and Pb during bituminous coal and pickling sludge co-combustion were studied in a horizontal tube furnace. Additives including NaCl, FeS2, water and kaolin were used to simulate coal with high chlorine, sulfur, moisture and ash content, respectively. The percentage of pickling sludge used in all conditions was 10%, and the additives added range was 1%–20%. The experimental results indicated that with increasing NaCl addition the percentage of As, Cu and Pb in bottom ash decreased significantly and the Mn percentage in fly ash increased slightly. Under FeS2 addition condition, Cu and Pb percentage in bottom ash increased significantly due to the incomplete decomposition of the generated CuFe2O4 and PbSO4 while the volatilization of As was promoted. With the increasing addition of water, a higher percentage of As moved into the fly ash from bottom ash, while the proportion of Pb in the fly ash decreased obviously. Under kaolin addition, the As partitioning showed a fluctuation trend, while for Pb and Cu the adsorption was the main effect and their distribution in bottom ash increased. Under all conditions, Cr and Ni partitioning were not affected by additives due to the non-volatility and stability of Cr, Ni and their compounds. Bottom ash XRD analysis results showed that CaF2 disappeared under NaCl addition condition and lots of Ca2Al2SiO7 generated. In addition, FeS2 addition caused more CaSO4 generated due to the sulfation reaction, while no obvious change of bottom ash composition was found under neither water nor kaolin addition.