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In this paper, a novel and facile synthetic method of 3-mercaptopropionic acid functionalized copper nanoclusters with aggregation-induced emission (AIE) induced by Cu2+ (Cu2+@MPA-Cu NCs) was developed by a one-pot reaction as a fluorescent probe for the detection of sulfide ion (S2-). The prepared Cu2+@MPA-Cu NCs behaved as aggregated clusters and had strong pink fluorescence under 365 nm UV light with excellent fluorescence emission at 610 nm. The quantum yield increased from 0.56% to 4.8% before and after Cu2+ added. The presence of S2- would strongly bind to Cu2+, which caused the structure of the aggregated Cu2+@MPA-Cu NCs to be destroyed and then the fluorescence quenched. On the basis of this principle, a fluorescent probe was constructed for the detection of S2- with a very good linearity in the range 0-600 μM (R2 = 0.9843) and a detection limit of 26.3 nM. Finally, the nanohybrids were successfully demonstrated for the application in the selective detection of S2- in food additives. This study essentially paved a new avenue for effectively developing an easy sensor platform for S2- measurements in food additives.

Changes of crystal structures, formation energies, electronic band structures and absorptions induced by sulfide ions substituting for oxygen ions in Sr3MgSi2O8-δSδ have been calculated by the first-principles calculation. Through the calculations, it can be found that crystal structures get enlarged with the increasing sulfide ion substituting concentrations. Band structures and densities of states make clear of the compositions of the valence bands and the conduction bands in Sr3MgSi2O8-δSδ. Band gap value of initial Sr3MgSi2O8 without any sulfide ion substitution is about 4.788 eV. Meanwhile, for the Sr3MgSi2O8-δSδ lattices with increasing sulfide ion substitutions, a decreasing trend of band gap values appeared and the minimum band gap gradually decreased to 2.705 eV till δ = 4. This is due to the hybridization of sulfide ion and oxygen ion in Sr3MgSi2O8-δSδ lattice which raised the top of valence band. After the oxygen ions have been totally replaced by the sulfide ion, the band gap grows up to 2.852 eV, which is smaller than that of Sr3MgSi2O8 without sulfide ions substitution. In addition, the calculated absorptions of Sr3MgSi2O8-δSδ gradually shifted from deep UV region to the blue area due to the sulfide ions substitutions. This makes Sr3MgSi2O8-δSδ more suitable for serving as luminescent host materials employed in the UV-pumped white WLEDs.

Microbiologically influenced corrosion (MIC) is a serious problem in the oil and gas industry. The most common microorganism responsible for MIC is sulfate-reducing bacteria (SRB) which produces detrimental sulfide ions into the environment. Currently, there are some prediction models that develop to predict corrosion rate caused by SRB. However, among the models, the prediction is limited to predict the general corrosion rate, whereas, SRB caused localized corrosion. Thus, the objective of this work is to predict the pitting depth caused by SRB using available empirical equation. The study showed that the pitting depth increased with the increasing of sulfide concentration. In contrast, the pitting depth decreased with increasing sulfite concentration. The decreasing of pitting depth is related to the inhibitive FeS film formed, while the increasing of pitting depth is caused by the decreasing of the film thickness in the presence of sulfite.

Effects of sodium chloride on the sulfidization flotation of cerussite (PbCO3) were investigated by micro-flotation tests, adsorption tests and zeta potential measurements. The micro-flotation test results indicated that sodium chloride effectively improved the sulfidization flotation performance of cerussite. The electrical double layers of cerussite particles were compressed in sodium chloride solution, thus providing more lead sites on the cerussite surface and promoting the adsorption of sulfide ions. In sodium chloride solution, more lead sulfide species were formed on the cerussite surfaces and improved its sulfidization flotation performance.

Sulfide ions (S2−) that are widely distributed in biological and industrial fields are extremely toxic and pose great harms to both ecological environment and human health. However, fluorescent sensors toward S2− ions commonly use S2−-recovered fluorescence of fluorophore that is first quenched mainly by metal ions. Fluorescent probe which enables direct, selective, and sensitive detection of S2− ion is highly desirable. Herein, we demonstrate one-step preparation of fluorescent ionic liquid–graphene quantum dots (IL-GQDs) nanocomposite, which can act as a fluorescent probe for direct and sensitive detection of S2− ion. The IL-GQDs nanocomposite is easily synthesized via facile molecular fusion of carbon precursor and in situ surface modification of GQDs by IL under hydrothermal condition. The as-prepared IL-GQDs nanocomposite has uniform and ultrasmall size, high crystallinity, and bright green fluorescence (absolute photoluminescence quantum yield of 18.2%). S2− ions can strongly and selectively quench the fluorescence of IL-GQDs because of the anion exchange ability of IL. With IL-GQDs nanocomposite being fluorescent probe, direct and sensitive detection of S2− is realized with a linear detection range of 100nM–10μM and 10μM–0.2mM (limit of detection or LOD of 23nM). Detection of S2− ions in environmental river water is also achieved.

The rheology of a partially hydrolyzed polyacrylamide (HPAM) solution plays an important role in its oil recovery during polymer flooding. However, multiple factors in brine, such as sulfide ions, cause a dramatic loss in the viscosity and oil recovery. To better understand the sulfide-induced viscosity loss and the consequent flow mechanisms in pore networks, the morphology of polymer solutions with and without sulfide ion was observed by scanning electron microscopy; and the variations of the pore scale flow fields were demonstrated by a microscopic visualization seepage experiment combined with Micro-PIV (Microscale Particle Image Velocimetry). The results showed that, with the presence of sulfide ion, the microstructure of the polymer changed from a uniform three-dimensional network structure to loose and uneven floccules, which resulted in viscosity loss (over 70% with 5-mg/L sulfide ion). Moreover, higher concentrations of sulfide ions (5 mg/L and 10 mg/L) resulted in earlier shear thinning characteristics than those with lower sulfide concentrations. Due to viscosity loss, the average flow velocity in the main stream of the microscopic seepage experiment increased more significantly than that without sulfide. However, the viscosity loss alone cannot independently explain the severe viscous fingering during the subsequent post-water flooding, which was about five times greater than that of the primary water flooding in terms of the velocity ratio between the mainstream and margin. A further pore-scale flow field analysis exhibited an eccentric and a bimodal velocity distribution in the throat along the radial and axial directions, respectively. The former distribution indicated that the adsorbed polymer on the pore wall was broken through by hydraulic shear due to the collapsed structure caused by sulfide ion. The latter suggested that another sulfide-induced impact was an earlier-occurring non-Newtonian characteristic with a low shear rate. Therefore, instead of viscosity loss, elastic loss is the dominant mechanism affecting the characteristics of the aggregate flow field under the action of sulfide. Microscopic flooding combined with Micro-PIV is a feasible and essential method to reveal pore scale flow mechanisms.

Here, we report the controllable synthesis of porous MnxCo1−xO microspheres and tunable catalytic activity in the oxidase mimicking reaction. Mn0.6Co0.4O possesses the best oxidase mimicking activity and can be used successfully in sulfide ion colorimetric detection with a low detection limit of 0.1 μM.

The effective synthesis of functional nanoplatforms for simple, selective, and sensitive hydrogen sulfide detection has received significant attention because of the toxicity of hydrogen sulfide. H...

The results of model experiments on the effect of transition elements (iron, manganese) and sulfide ions on the values of chemical (COD) and biochemical oxygen demand (BOD) are presented. It is shown that, in the presence of transition elements in water, BOD is overestimated. In the presence of 100 mg/L of iron(II) and >0.05 mg/L of sulfides in water, the BOD values exceed those of COD.

Reaction of AgC≡CtBu with (EtO)2PS2Na at room temperature leads to the isolation of two new silver(I)-ethynide compounds incorporating the dithiophosphate ligand, namely, {CO3@(Ag3)4(C≡CtBu)4(EtO)2PS2]6}·0.5H2O (1) and {(CO3)2@Ag26(C≡CtBu)16[(EtO)2PS2]4}·2(OH)·4MeOH·6H2O (2). Besides, we obtain another three silver(I)-ethynide clusters S@Ag11(C≡CtBu)2[(EtO)2PS2]7 (3), {S@Ag14(C≡CPh)8[(EtO)2PS2]4(TMEDA)2}·5MeOH (4), and {S@Ag14(C≡CPh)8[(iPrO)2PS2]4(TMEDA)2}·7CH3OH (5), with AgC≡CR (R= tBu, Ph) and (RO)2PS2Na (R= Et, iPr) as the starting materials. Complexes 1–2 are templated by a carbonate anion in situ generated from the fixation of atmospheric CO2 in a basic TMEDA-containing solution, and TMEDA can also lead to the disassembly of dithiophosphate to give a sulfide ion as the template for the generation of 3–5.

In the present work, we use β-casein as a model protein to prepare a smart β-casein stabilized Pt nanoparticle (CM-PtNP) with peroxidase mimicking activity and systematically investigate sulfide-mediated switching effect and mechanism of CM-PtNP nanozyme's activity. Sulfide-mediated activity switching effect depends heavily on the physicochemical properties of nanozymes and the identity of substrate. On one hand, the binding of sulfide to a Pt nanozyme surface leads to the transform from Pt2+ to Pt0, resulting in more active sites and the activity "switching on"; on the other hand, the binding of sulfide ions via Pt-S interaction blocks the active sites, resulting in the activity "switching off". For substrates 3,3',5,5'-tetramethylbenzidine and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt, the two factors play different decisive roles since the interaction of substrate molecules with nanozyme allows their different distributions on nanozyme surfaces. By virtue of this specific response, excellent sulfide colorimetric sensors with different limits of detection were developed based on CM-PtNP with different substrates. This is the first report about a fundamental understanding of how substrates influence the anion-mediated activity switching effect by illuminating the nature of anion-nanozyme interaction and nanozyme-substrate interaction. This may be useful to rationally predict the environment factors on the activities of the nanozyme and to design an effective signal amplification based on target-induced nanozyme deactivation/activation.

S2―-responsive nanocontainers are constructed by assembling zeolitic imidazolate framework-8 onto hollow mesoporous silica nanoparticles. Spontaneous leakage of incorporated biocides is nearly restrained and release initiates when S2― is higher than 0.04 mM. Such nanocontainers can respond to S2― fluctuation derived from microbiologically influenced corrosion (MIC) induced by sulfate reducing bacteria (SRB). The protective performance of coating with smart nanocontainers is evaluated in SRB environment. It demonstrates the intelligent coating exhibits the fewest bacterial settlement, highest impedance (3.31 × 107 Ω cm2) and lowest corrosion current density (1.36 × 10−10 A cm−2) after 14-day immersion, revealing the optimal resistance to MIC.

A novel compound TPI-H containing triphenylimidazole chromophore is synthesized and employed as fluorescent probe for sequential detection of Cu2+ and S2-. With three binding sites in its molecular structure, TPI-H exhibits highly selective binding towards Cu2+ and results in an apparent fluorescence "on-off" behavior. Fluorescence intensity is linear with the Cu2+ concentration, and the detection limit can be down to 8.7nM. Furthermore, the in-situ generated ensemble between TPI-H and Cu2+ (TPI-H-Cu(II)) can be used to detect S2- with a low detection limit of 15.6nM through Cu2+ displacement method. In addition, the potential utility of the probe for the detection of Cu2+ and further S2- in biological system is investigated by cell imaging.

Effluents from production of petroleum bitumens were submitted to treatment by three different AOPs at basic pH (i.e., O3, H2O2 and the combination of O3 and H2O2, a so-called peroxone). The paper presents studies on the identification and monitoring of the volatile organic compounds (VOCs) degradation present in the effluents and formation of byproducts, COD, BOD5, sulfide ions, biotoxicity, and biodegradability changes during treatment. Peroxone at 25 °C with a ratio of oxidant in relation to the COD of the effluents (rox) of 0.49 achieved 43% and 34% of COD and BOD5 reduction resulting in the most effective AOP studied. S2– ions were effectively oxidized in all technologies studied. Ozonation at 25 °C and with a rox of 0.34 was the most effective process to degrade VOCs. Decrease in the biotoxicity was reported in O3 and peroxone processes. Byproduct formation in different AOPs was reported. These reductions revealed that these technologies are effective if used as pretreatment methods.

The interaction between sulfide-ion species and smithsonite surfaces and its response to flotation performance were investigated by means of microflotation experiments, surface-adsorption tests, zeta-potential determination, and X-ray photoelectron spectroscopy (XPS) analysis. The microflotation experiments results indicated that addition of Na2S elicited a positive effect on the smithsonite floatability within an appropriate concentration range (

Herein, we report a simple and rapid method for the visual detection of sulfide ion in an aqueous environment with high sensitivity and specificity by using ciprofloxacin capped silver nanoparticles (Cip-AgNPs). The sensor system can be used to detect as low as 16 nM of S2− in aqueous environment by only naked-eye and 0.112 nM of S2− by absorption spectrophotometer. The visual detection limit of 16 nM is much lower than the maximum allowable level of S2− (15 μM) in the drinking water defined by the world health organisation. The proposed sensor detects S2− at a wide range of pH and also demonstrated to sense S2− in tap water and river water, with good recovery. For portable use, we synthesized highly stable Cip-AgNPs on cotton and demonstrated good sensitivity against S2− ion. As prepared Cip-AgNPs embedded cotton detects S2− in an aqueous solution and S2− in a gaseous state, indicating that our sensor meets the requirement for on-site detection of S2− in the environment by only-naked eye.

We develop a simple assay for highly selective and sensitive fluorescence detection of sulfide ions (S2−) using glutathione-protected gold nanoclusters (GSH-Au NCs). This approach was based on the much higher affinity of CuS than that of the Cu–GSH complex, which makes the fluorescence of the NCs quenched by Cu2+ recover upon addition of S2−. Importantly, the assistance of Cu2+ enables S2− detection in the “turn-on” mode, eventually enhancing detection sensitivity toward S2− about 15 times more compared to that in the “turn-off” mode. Under the optimal conditions, the linear fluorescence response toward S2− was given within the concentration range of 2 to 24 μM with a low detection limit of 0.7 μM. Also, the GSH-Au NCs show good reusability for S2− detection due to effective removal of the bridging reagent Cu2+ by S2−. This phenomenon is further exploited as an integrated logic gate and successfully employed for imaging S2− in living cells.

Li2S-P2S5 thin-film solid electrolytes are synthesized by using room-temperature thermal evaporation for use as lithium-ion conductors for all-solid-state Li-ion batteries. The local structures of 75.51Li2S:24.49P2S5 and 77.64Li2S:22.36P2S5 prepared in this way have hetero units that facilitate lithium-ion mobility. The lithium-ion conductivity at room temperature for the 77.64Li2S:22.36P2S5 thin-film (4.0 × 10−6 S cm−1) is higher than that for the 75.51Li2S:24.49P2S5 thin-film (1.2 × 10−6 S cm−1). The increased ion conductivity in the 77.64Li2S:22.36P2S5 film is due to the additional local P2S74− structure that forms a glassy state during the thermal evaporation process. The local structure can lead to a high mobility of Li+ ions in the Li2S-P2S5 system due to the non-bridging sulfide ions. Lithium-ion-conducting thin-films prepared by using thermal evaporation, as reported in this study, are promising solid electrolytes.

Wheat and barley are often cultivated also in paddy fields in winter in Japan. The drainage of paddy fields is often poor. The seedling establishment of wheat and barley is more prone to become poor if it rains heavily after sowing. The flooding damage on seedling establishment is thought to be caused by many factors. The generation of sulfide ions in flooded and reduced soil is thought to be one factor of the flooding damage. In this study, the effect of seed coating with molybdenum compounds, which suppress the generation of sulfide ions, on the flooding damage of wheat and barley seedling establishment. Two poorly soluble molybdenum compounds were coated on wheat or barley seeds at different amounts. Coated seeds were sown in soil and soon flooded for 2 d at 20 °C. When seeds were not coated with molybdenum compounds, rates of seedling establishment were no more than 32%. However, when any molybdenum compounds of .05–.5 mol-Mo kg−1 were coated, seedling establishment was significantly improved and rates of seedling establishment were no less than 54%. However, when sown seed were not flooded, the establishment rates of the seeds, which were coated with a molybdenum compound of no less than .1 or .2 mol-Mo kg-1, were significantly decreased. Accordingly, coating of molybdenum compounds could improve the seedling establishment of coated seeds under flooded condition, but might impair the seedling establishment of coated seeds under unflooded condition.

Red-emitting lysozyme-stabilized silver nanoclusters (Lys-Ag NCs) were synthesized and utilized as a fluorescent probe for sensing sulfide ions (S2−) based on fluorescence quenching. Hence a new method for the detection of S2− was developed. Under optimized experimental conditions, the probe exhibited a stable response for S2− over a concentration range from 5.0 × 10−6 M to 1.0 × 10−4 M with a detection limit of 1.1 × 10−6 M. The feasibility of the proposed method was further demonstrated through the detection of S2− in real samples. The results showed satisfactory recoveries in the range of 97.0–101.4%. Meanwhile, the possible sensing mechanism for the detection of S2− was also discussed. The proposed method for the detection of S2− has potential application in the environmental pollutant analysis.

The adsorption of sulfide ions on cerussite surfaces and implications for flotation were studied by X-ray photoelectron spectroscopy (XPS) analysis, micro-flotation tests, and surface adsorption experiments. The XPS analysis results indicated that lead sulfide species formed on the mineral surface after treatment by Na 2 S, and the increase in the Na 2 S concentration was beneficial for sulfidization. In addition to the content of lead sulfide species, its activity, which was determined by the proportion of sulfide, disulfide and polysulfide, also played an important role in cerussite sulfidization. Micro-flotation tests results demonstrated that insufficient or excessive addition of Na 2 S in pulp solutions has detrimental effects on flotation performance, which was attributed to the dosage of Na 2 S and the activity of lead sulfide species formed on the mineral surface. Surface adsorption experiments of sulfide ions determined the residual S concentrations in pulp solutions and provided a quantitative illustration for the inhibition of cerussite flotation by excessive sulfide ions. Moreover, it also revealed that sulfide ions in the pulp solution were transformed onto the mineral surface and formed lead sulfide species. These results showed that both of lead sulfide species and its activity acted as an important role in sulfidization flotation process of cerussite.

Metal sulfide ion-exchangers (MSIEs) have emerged as a new class of promising sorbents for the removal of toxic and radioactive metals from wastewater., Metal sulfide ion-exchangers (MSIEs) represent a new addition to the field of ion exchange materials. This is a growing class of materials that display exceptional selectivity and rapid sorption kinetics for soft or relatively soft metal ions as a result of their soft basic frameworks. Without requiring functionalization, they outperform the most efficient sulfur-functionalized materials. This is the first review focusing on this class of materials; it covers the most important MSIEs, focusing on their synthesis, structural features and ion-exchange chemistry. Furthermore, recent developments in the engineered and composite forms of MSIEs are described. Future research opportunities are also discussed in the hope of inspiring additional scientists to engage in this new area of research on sulfidic ion-exchange materials.

Different types of photolytic and photocatalytic advanced oxidation processes (AOPs) were used for treatment of refinery effluents from bitumen production. The treatment efficiency was evaluated by analyzing chemical oxygen demand (COD), biological oxygen demand (BOD5), volatile organic compounds (VOCs) and sulfide ions concentration. The studies revealed a synergistic effect of application of external oxidants (O3, H2O2, O3/H2O2) with TiO2 and UV applied for improved COD and BOD5 reduction as well as the degradation of the VOCs present in the effluents. Among studied processes a photocatalytic process combined with peroxone (TiO2/UV/O3/H2O2) was the optimal and the most economical technology. It allows to reduce 38 and 32% of COD and BOD5 respectively and degrade 84% of total VOCs in 280 min of treatment. At this conditions the reduced COD exceeds over 30% a theoretical value based on the dose of oxidants, which proves the importance of photocatalysis in the developed technology. The sulfide ions were completely depleted in all experiments in the first 30 min of treatment. The addition of TiO2 in the AOPs technology revealed a decrease in the process cost using less amount of chemicals achieving similar treatment efficiency when comparing with photolytic and non-catalytic technologies. The application of these technologies can be conducted in two alternative scenarios; whether to deplete the sulfides ions concentration or to maximize the treatment efficiency. In both options, the technologies studied are promising as a pre-treatment before other types of AOPs effective at neutral/acidic pH values or before a biological treatment stage. Further studies should be developed, by scaling up the process to a pilot scale in a real case scenario to check the possibility of its implementation in the industrial practice.

Herein, we fabricate a novel metal-phenolic supramolecular film on aluminium, which can control release of loaded biocides when S2− concentration is higher than 10 mM or in sulfate reducing bacteria (SRB) environment with a long incubation period. The protection effect of the film on microbially influenced corrosion (MIC) induced by SRB is analyzed with fluorescence microscopy and electrochemical measurement. A novel microbiological corrosion protection mechanism is proposed based on its effective roles to suppress SRB settlement and insulate corrosive medium. The intelligent film maintains a longtime antibacterial behavior owing to its S2--responsive character, which enhances the microbiological corrosion resistance.

The cutting-edge nanozyme-based strategy for rapid detection remains significantly limited by the lack of simple synthetic method with ideal catalytic activity. In this regard, 2D nanozymes has recently emerged as a group of promising nanozymes because of their unique enzyme mimicking properties. Herein, via one-pot bottom-up co-calcination, we report a robust strategy to promote the peroxidase-like activity of 2D nanozyme by rational fabricating a 2D/2D heterojuncted nanozyme: MoS2/g-C3N4 heterojuncted nanosheets (MoS2/g-C3N4 HNs). With merits of the acceleration of electron transfer and the synergistic effect of MoS2 and g-C3N4 as well as high affinity to the catalytic substrates, the 2D/2D MoS2/g-C3N4 heterojuncted nanozyme shows enhanced peroxidase-like activity over the pure g-C3N4 nanosheets and MoS2 nanosheets. As a proof-of-concept application, a colorimetric sensor based on this 2D/2D heterojuncted nanozyme was developed to detect sulfide ions (S2−), and the detection limit was found to be as low as 37 nM. Therefore, the current work not only demonstrates a powerful strategy to improve the activity of 2D nanozymes but also establish a facile approach for water-safety monitoring.

Based on the localized surface plasmon resonance (LSPR) technology, a novel plasmonic nanosensor with high sensitivity and high selectivity was prepared for the detection of trace sulfide ions on an individual Au@Ag nanoparticle. Furthermore, it could be used to monitor the sulfurization on an individual Au@Ag nanoparticle surface observed under dark-field microscopy (DFM).

Immensely sensitive, accurate, and simple on-site colorimetric sensor has been developed for the quantitative detection of the sulfide ion in human blood plasma. The colorimetric sensor consists of lead-ion-modified silica-gel powders placed in a glass tube. The powder color changes upon reaction with sulfide ions in blood plasma. It is capable of easily detecting toxic sulfide ion by using a glass tube with an inner diameter of 3 mm. By employing the type of colorimetric sensor to a blood sample, it is possible to detect the sulfide ion with a concentration limit of 0.1 ppm and excellent reproducibility, thus making it superior to conventional analysis methods that need multiple preparation processes and various sophisticated instruments. Since the sensor reported here is insensitive to environmental conditions such as temperature or humidity, and is featured by simplicity, fast response, high sensitivity, and easily understandable results based on absolute affirmative/negative response, it is expected to be effectively used for on-site applications such as detecting poisonous ions in blood samples.

Semi-industrial synthesis of a calcium polysulfide solution, a good demercurizing reagent in the technology for utilization of mercury-containing wastes, was developed. The development of a technology for utilization of wastes of this kind with the use of a calcium polysulfide solution is primarily associated with choosing the Hg: CaS n ratios. The Hg: CaS n ratio was found from the concentration of sulfide ions in the CaS n solution because the composition of the CaS n solution, where n = 4–6, is not constant. A photocolorimetric method was developed for determining the concentration of sulfide ions in the CaS n solution. The method was used for rapidly finding the content of sulfide ions in the CaSn solution on batches of industrial solutions in refinement of the technology for waste demercurization. The results obtained in determining the content of sulfide ions in a CaS n solution were confirmed by the independent titrimetric method.

A sensitive and selective method has been developed for the determination of sulfide ions (S2−) based on S2− triggered fluorescence quenching of papain-directed Au nanoclusters. Under the optimized experimental conditions, the proposed method facilitated the determination of S2− in the linear range 0.5–80.0 μM; the limit of detection was 0.38 μM at a signal-to-noise ratio of 3. In addition, the fluorescence intensity decreased selectively in response to S2− relative to other ions. Based on multiple analyses, it is proposed that the fluorescence was quenched through the unique reactions between S2− and the Au atoms/ions, and that the formation of Au2S induced aggregation of the Au nanoclusters. The practicality of the proposed method for the determination of S2− in natural water samples was verified. The results were in good agreement with those determined by the methylene blue colorimetric method. This new method may broaden the scope of techniques available for the determination of S2−.

A hydroxynaphthyl hydrazine linked calix[4]arene derivative ( 4 ) has been designed, synthesized and evaluated for multi ion recognition. 4 not only recognizes copper ions selectively through a change in color, UV–Vis and fluorescence spectrum but the resultant metallo-supramolecular complex ( 4 ·Cu 2+ ) emulates specific recognition of S 2− ions as well.

Sulfide- and azide-selective optical signaling using a single nitrobenzoxadiazole (NBD)-based probe was investigated. NBD-pivalate showed colorimetric signaling for sulfide ions via cleavage of the NBD–O bond to generate NBD–SH. It also showed chromogenic and fluorogenic signaling for azide ions by O–COBut cleavage to yield NBD–OH under the same conditions.

In Japan, soybeans are generally cultivated in paddy fields which often have poor drainage. West of the Kanto region, the seeds are sown in the rainy season. Therefore, the seedling establishment is prone to damage by the rain after sowing. The generation of sulfide ions in flooded and reduced soil is thought to be one factor causing this flooding damage. Sincemolybdate ions suppress the generation of sulfide ions, the effect of coating soybean seeds with molybdenum compounds, onthe seedling establishment under a flooded condition was examined. Soybean seeds were coated with several kinds of poorly-soluble molybdenum compounds at different concentrations. The coated seeds were sown in soil and then flooded for 3 d at 25 – 30°C. Seedlings were not established from seeds not coated with molybdenum compounds. Seedling establishment was appreciably improved by coating the seeds with a molybdenum compound at the rate of 0.5 – 1 mol-Mo kg–1 seed. Seedling establishment was especially improved by coating...

Nickel sulfide (NiS) nanoparticles were synthesized by a simple electrochemical route. In this study, synthesis conditions of nickel sulfide nanoparticles were optimized by Taguchi robust design. The current application of the Taguchi method was successful in optimizing the experimental parameters of the electrochemical synthesis procedure of nickel sulfide nanoparticles. The effects of several main procedure factors (i.e., sulfide ion concentration, applied voltage, stirring rate and reactor temperature) on the particle size of synthesized nickel sulfide particles were investigated. The significance of these factors on the diameter of nickel sulfide particles was evaluated by the analysis of variance (ANOVA) and the optimum conditions for the preparation of nickel sulfide nanoparticles by the proposed electrochemical method was proposed. The prepared NiS nanoparticles at optimum conditions were characterized by various techniques i.e., SEM, TEM, XRD, EDX, FT-IR, UV–vis and PL.

The paper presents the results of studies on chemical treatment of effluents from production of bitumen of petroleum origin. Due to the presence of sulfide ions, the pH of these effluents is strongly alkaline. Several Advanced Oxidation Processes (AOPs) were studied, including the use of hydroxyl and sulfate radicals oxidants, the hydrodynamic cavitation as well as sonocavitation. The best processes allow to obtain 45% reduction of chemical oxygen demand value (COD) along with effective degradation of the majority of the volatile organic compounds present in the effluents. Some of the studied processes, especially the one using sonocavitation revealed to produce high amounts of VOCs by-products.

A simple and rapid spectrophotometric method for flow injection determination of sulfite in tan wastewater is described. It was based on the fade reaction of sulfide ion with Ag (I)- (5-Bromo-2-pyridylazo)-5-diethyl-aminophenol (5-Br-PADAP) in NaAc-HAc medium. The optimum conditions allow a linear calibration range of 0.01-1.10 μg ml-1sulfide ion. The detection limit is 0.0043 μg ml-1 (S/N=3), and the relative standard deviation for night replicate measurements is 2.1% for 0.5μg ml-1of sulfide ion. The procedure has been applied to the determination of sulfide in tannery wastewater. The results were in good agreement with those obtained by methylene blue spectrophotometric method.

In this paper, elemental mercury (Hg0) re-emissions from simulated wet flue gas desulfurization (WFGD) solutions were evaluated in the presence of thiocyanate ions (SCN−) or sulfide ions (S2− and HS−). Experimental results revealed that both thiocyanate ions and sulfide ions could inhibit the reduction of oxidized mercury to Hg0. The inhibition effect of SCN− was mainly attributed to the formation of HgSO3SCN− and HgSCNX−(X–2) (X = 2–4). It was found that the mercury reduction process in the presence of sulfide ions followed different mechanism under acidic or alkaline condition, though the formation of stable HgS could be ascribed to the main inhibition reason. Under acidic condition, the bivalent mercury ions may not directly combine with sulfide ions to form HgS. This had led to a weaker inhibition effect under the acidic condition compared to that under alkaline condition.

Electrocatalytic oxidation of sulfide ion on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNTs) and a copper (II) complex was investigated. The Cu(II) complex was used due to the reversibility of the Cu(II)/Cu(III) redox couple. The MWCNTs are evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on Cu(II) complex adsorbed on MWCNTs immobilized on the surface of GCE. The modified GCE was applied to the selective amperometric detection of sulfide at a potential of 0.47 V (vs. Ag/AgCl) at pH 8.0. The calibration graph was linear in the concentration range of 5 µM–400 µM; while the limit of detection was 1.2 µM, the sensitivity was 34 nA µM−1. The interference effects of SO3 2−, SO4 2−, S2O3 2−, S4O6 2−, Cysteine, and Cystein were negligible at the concentration ratios more than 40 times. The modified electrode is more stable with time and more easily restorable than unmodified electrode surface. Also, modified electrode permits detection of sulfide ion by its oxidation at lower anodic potentials.

We report a universal sulfide-assisted synthesis strategy to prepare dumbbell-like M-Ag heterodimers (M = Pd, Au, Pt). Sulfide ions can give fine control over the reaction kinetics of Ag precursors, resulting in the anisotropic overgrowth of Ag to realize the dumbbell-like heterodimers irrespective of the surface facets or components of the M domain. The M-Ag heterodimers were facilely transformed to M-Ag2S heterodimers via a simple sulfidation reaction. This study provides a versatile approach to realizing not only metal-metal heterodimers but also semiconductor-metal heterodimers and will pave the way for designing heteronanostructures with unprecedented morphologies and functions.

1) JFE Mineral Corporation, 1, Niihama-cho, Chuo-ku, Chiba, 260-0826 Japan. 2) JFE steel Corporation, 1, Kawasakicho, Chuo-ku, Chiba, 260-0835 Japan. 3) Formerly Environmental Research and Management Center, Hiroshima University. Now at Research Center for Inland Seas, Kobe University, 1-1, Rokkoudai-Chou, Nada-ku, Kobe, 657-8501 Japan. 4) Graduate School of Biosphere Science, Hiroshima University, 4-4-1, Kagamiyama, Higashihiroshima, 739-0046 Japan. 5) Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 1-1-2, Katahira, Aoba-ku, Sendai, 980-8577 Japan.

Although Na2S doesn’t depress the flotation of molybdenite, as the most utilized depressant, its effect on the flotation of molybdenite in the case where Pb2+ is involved has not been investigated yet. In this work, the flotation behavior of molybdenite in Pb2+ solution with or without Na2S was investigated. The mechanism was also studied by Zeta potential measurement, SEM-EDX, AFM and XPS analysis. The results indicated Pb2+ depressed the flotation of molybdenite, and Na2S enhanced the depression effect significantly. The depression effect depended on pH in both Pb2+ and Pb2+-Na2S solutions. In Pb2+ solution, the depression is mainly due to formation of PbS on molybdenite surface. While in Pb2+-Na2S solutions, the deterioration of flotation was majorly attributed to coating of strongly hydrophilic Pb(OH)2 precipitate on molybdenite surface. Keywords: Molybdenite, Flotation, Pb2+, Sodium sulfide, Depression

The effect of FeO and CaO on the sulfide capacity in MgO-SiO2-FeO based slags equilibrating with Fe-Ni alloys at 1773 K and 1873 K (1500 °C and 1600 °C) was investigated. The sulfide capacity in the MgO-SiO2-FeO and MgO-SiO2-CaO-FeO slags increased with higher FeO content and higher temperatures due to an increase in the activity of O2− and a decrease in the activity coefficient of sulfide ion in slag. The sulfide capacity of the MgO-SiO2-CaO-FeO slag also increased with an increase in the CaO content due largely to the increase in the activity of O2−. Furthermore, CaO and FeO seem to be more effective than MgO in increasing the sulfide capacity in the MgO-SiO2-CaO-FeO slag system. In addition, the comparison of the experimental results with the theoretical estimate using the modified empirical optical basicity showed relatively good linear agreement.

In 1905, the U.S. Pharmacopeial Convention, the nonprofit standards-setting organization known as USP, introduced a method to check for heavy metals in U.S. pharmaceuticals. More than 100 years later, drug manufacturers still use the same chemistry to determine whether the level of 10 metal impurities is acceptable in their products. Exposure to metals such as arsenic and mercury can have negative health effects; the substances can also weaken drug stability. But rather than targeting individual metals for their toxicity and setting limits accordingly, the old USP test, described in chapter 231 of the group’s standards, measures all of the metals that can react with a sulfide ion to form a visible precipitate. The aggregate threshold dictates the acceptable limit for all the metals combined. Regulators and drug manufacturers agree on the need to modernize elemental impurity analysis. However, they disagree on the substance of a new limit-based standard and the ...

Solid solutions are synthesized in the system of CaY2S4-Yb2S3. Temperature and concentration dependences of electrolytic properties are studied, the sulfide ion-based conductivity is confirmed. It is shown that the high contribution of ion conductivity in the synthesized phases is due to formation of charged vacancies. Mechanisms of defect formation are suggested.