Showing papers on "Sodium sulfide published in 2016"

Performance Enhancement and Mechanistic Studies of Room-Temperature Sodium–Sulfur Batteries with a Carbon-Coated Functional Nafion Separator and a Na2S/Activated Carbon Nanofiber Cathode

Abstract: Operation of sodium–sulfur batteries at room temperature has been proposed and studied for about a decade, but polysulfide-shuttle through the traditional battery separator and low-utilization of the sulfur cathode commonly have been the major challenges. Also, because of the highly active nature of the sodium metal, the conventional room temperature sodium–sulfur (RT Na–S) battery concept with the sodium–metal anode and elemental sulfur cathode imposes serious safety concerns. To overcome the above difficulties, we present here a RT Na–S system with an advanced membrane-electrode-assembly (MEA) comprising a carbon-coated, presodiated Nafion membrane (Na-Nafion) and a sodium sulfide (Na2S) cathode. The Na-Nafion membrane provides a facile Na+-ion conductive path and serves as a cation-selective shield to prevent the migration of the polysulfides to the anode. The carbon coating on the Na-Nafion plays an upper-current-collector role and thereby improves the electrochemical utilization of the active Na2S. E...

Ag2S silver sulfide nanoparticles and colloidal solutions: Synthesis and properties

Abstract: Powders of silver sulfide Ag2S have been synthesized by hydrochemical bath deposition from aqueous solutions of silver nitrate and sodium sulfide in the presence of sodium citrate or EDTA-H2Na2. Colloidal non-toxic solutions of Ag2S nanoparticles have been prepared by chemical condensation method from the same aqueous solutions. The size of silver sulfide particles in deposited powders and colloidal solutions has been estimated with the use of X-ray diffraction, dynamic light scattering, transmission electron microscopy and Brunauer–Emmett–Teller techniques. By varying the ratio between the concentrations of reagents in the initial reaction mixtures it is possible to deposit Ag2S nanoparticles with pre-assigned average size ranging in the interval from about 500 nm down to about 40 nm. The average size of silver sulfide Ag2S nanoparticles in stable colloidal solutions is equal 10–20 nm. Special attention has been devoted to investigation of stability of synthesized colloidal solutions on the duration of their storage. The UV–Vis absorption spectra of colloidal solutions and optical reflectance of nanopowders of silver sulfide have been studied. Decreasing of average size of Ag2S nanoparticles from ∼500 nm down to ∼60 nm leads to increasing of energy band gap E g from 0.88 to 1.21 eV. Studied colloidal solutions and nanopowders of silver sulfide possess the potential antibacterial activity.

Graphite‐Nanoplate‐Coated Bi2S3 Composite with High‐Volume Energy Density and Excellent Cycle Life for Room‐Temperature Sodium–Sulfide Batteries

Abstract: Graphite-nanoplate-coated Bi2 S3 composite (Bi2 S3 @C) has been prepared by a simple, scalable, and energy-efficient precipitation method combined with ball milling. The Bi2 S3 @C composite was used as the cathode material for sodium-sulfide batteries. It delivered an initial capacity of 550 mAh g(-1) and high stable specific energy in the range of 275-300 Wh kg(-1) at 0.1 C, with an enhanced capacity retention of 69 % over 100 cycles. The unique structure demonstrates superior cycling stability, with a capacity drop of 0.3 % per cycle over 100 cycles, compared with that of bare Bi2 S3 . The sodium storage mechanism of Bi2 S3 was investigated based on ex situ X-ray diffraction and scanning transmission electron microscopy.

Staphylococcus aureus sqr Encodes a Type II Sulfide:Quinone Oxidoreductase and Impacts Reactive Sulfur Speciation in Cells.

Abstract: Recent studies implicate hydrogen sulfide (H2S) oxidation as an important aspect of bacterial antibiotic resistance and sulfide homeostasis. The cst operon of the major human pathogen Staphylococcus aureus is induced by exogenous H2S stress and encodes enzymes involved in sulfide oxidation, including a group I flavoprotein disulfide oxidoreductase sulfide:quinone oxidoreductase (SQR). In this work, we show that S. aureus SQR catalyzes the two-electron oxidation of sodium sulfide (Na2S) into sulfane sulfur (S0) when provided flavin adenine dinucleotide and a water-soluble quinone acceptor. Cyanide, sulfite, and coenzyme A (CoA) are all capable of functioning as the S0 acceptor in vitro. This activity requires a C167–C344 disulfide bond in the resting enzyme, with the intermediacy of a C344 persulfide in the catalytic cycle, verified by mass spectrometry of sulfide-reacted SQR. Incubation of purified SQR and S. aureus CstB, a known FeII persulfide dioxygenase-sulfurtransferase also encoded by the cst operon...

Palygorskite in sodium sulphide solution via hydrothermal process for enhanced methylene blue adsorption

Abstract: Palygorskite (PAL) has been recognized as a potential adsorbent for the removal of various dyes from aqueous solution, and so how to enhance its adsorption capability by an efficient approach becomes the subject of great interests. Herein, natural PAL was modified via a simple one-pot hydrothermal process in the presence of sodium sulphide to enhance the adsorption capabilities. The resultant material was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and field-emission scanning electron microscopy, and the adsorption properties were evaluated using methylene blue (MB) as the model dye to explore the synergetic effect of hydrothermal process and sodium sulphide on the structure, physico-chemical features and adsorption properties. It was found that the PAL rod crystal was partially evolved as new silicate with relatively higher adsorption activity. The adsorption capacity for MB evidently enhanced from 129.71 mg/g to 187.56 mg/g after hydrothermal modification, and the adsorption kinetics can be accurately fitted by a pseudo-second-order model. The chemical adsorption is the main driving force for the adsorption process, and the intensified electrostatic and hydrogen-bonding interaction between MB and PAL and the chemical association of –Si–O – groups with MB molecules plays a key role to enhance the adsorption properties.

Facile synthesis, structure, and properties of Ag 2 S/Ag heteronanostructure

Abstract: Ag2S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag2S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag2S and Ag nanoparticles is 45–50 and 15–20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag2S acanthite transforms into superionic β-Ag2S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag2S/Ag heteronanostructure is proposed. The UV–Vis optical absorption spectra of colloidal solutions of Ag2S/Ag heteronanostructures have been studied.

Biogas desulfurization using autotrophic denitrification process

Abstract: The aim of this study was to evaluate the performance of an autotrophic denitrification process for desulfurization of biogas produced from a chicken manure digester. A laboratory scale upflow fixed bed reactor (UFBR) was operated for 105 days and fed with sodium sulfide or H2S scrubbed from the biogas and nitrate as electron donor and acceptor, respectively. The S/N ratio (2.5 mol/mol) of the feed solution was kept constant throughout the study. When the UFBR was fed with sodium sulfide solution with an influent pH of 7.7, about 95 % sulfide and 90 % nitrate removal efficiencies were achieved. However, the inlet of the UFBR was clogged several times due to the accumulation of biologically produced elemental sulfur particles and the clogging resulted in operational problems. When the UFBR was fed with the H2S absorbed from the biogas and operated with an influent pH of 8-9, around 98 % sulfide and 97 % nitrate removal efficiencies were obtained. In this way, above 95 % of the H2S in the biogas was removed as elemental sulfur and the reactor effluent was reused as scrubbing liquid without any clogging problem.

Sodium Sulfide, a Hydrogen Sulfide-Releasing Molecule, Attenuates Acute Cerebral Ischemia in Rats

Abstract: Summary Aims Acute cerebral ischemia may lead to ischemic stroke, which is a major cause of death and disability worldwide. Hydrogen sulfide (H2S) functions importantly in mammalian systems. The present work was designed to study the effect of sodium sulfide, a donor of H2S, on acute cerebral ischemia. Methods Acute cerebral focal ischemia was produced by middle cerebral artery occlusion (MCAO) in Sprague-Dawley (SD) rats. Bilateral vertebral arteries and common carotid arteries were blocked to establish cerebral global ischemia in SD rats. Acute cerebral anoxia was produced by hypobaric anoxia in C57BL/6 mice and hypoxic anoxia in SD rats. Nimodipine and aspirin were set as positive control separately. Results Infarct size after MCAO was decreased by sodium sulfide. Sodium sulfide improved cerebral energy metabolism after cerebral global ischemia and prolonged survival time of animals with acute cerebral anoxia. In addition, increased cerebral blood flow and decreased cerebrovascular resistance, blood viscosity, and thrombogenesis were observed in animals treated with sodium sulfide. In cultured neurons, sodium sulfide increased cell viability and decreased cell apoptosis induced by oxygen-glucose deprivation. Conclusion Sodium sulfide, a H2S donor, presents protective effect on acute cerebral ischemia, and might be a promising therapeutic drug.

Beneficiation method for copper sulfide ore containing easily-sliming gangue minerals

Abstract: The invention relates to a beneficiation method for copper sulfide ore containing easily-sliming gangue minerals. According to the method, lime is adopted as pH regulator and pyrite depressant of flotation pulp of the copper sulfide ore containing the easily-sliming gangue minerals; sodium sulfide serves as activator of a small number of copper oxide minerals in the ore; sodium hexametaphosphate, sodium silicate or ethylenediamine serves as gangue slurry dispersant; a combination of butyl xanthate and other collectors serves as a collector of copper sulfide minerals; terpernic oil serves as foaming agent. The ore is subjected to primary grinding, primary roughing, primary scavenging and three-time concentration; the ore pulp is subjected to strong stirring and pulp mixing before starting to be subjected to primary roughing, primary scavenging and primary concentration, so that copper contained in the ore is efficiently recovered. According to the method, through reasonable combination and addition of chemicals, the ore grinding and pulp mixing process is strengthened, the adverse influence of gangue slurry on copper sulfide mineral floatation is eliminated, the surface characteristics of copper sulfide minerals are improved, the preferential adsorption of the collector on the surfaces of the copper sulfide minerals is enhanced, and accordingly, compared with a conventional method, the copper grade and the copper recovery rate of copper concentrate are substantially increased.

Silver Sulfide Nanoparticles with a Carbon-Containing Shell

Abstract: Silver sulfide nanoparticles have been synthesized through chemical deposition from aqueous solutions of silver nitrate and sodium sulfide in the presence of sodium citrate as a complexing agent and stabilizer. The nanoparticles have a Ag2S core with a monoclinic crystal structure, covered with a carbon-containing citrate shell. Varying initial reactant concentrations, we can obtain core/shell nanoparticles with a tailored Ag2S core size and carbon-containing shell thickness.

Structural and Electrical Properties of Cadmium Sulfide Nanoparticles: A Simple Chemical Route

Abstract: Structural and electrical properties of the nanocrystalline cadmium sulfide (CdS) powder were effectively synthesized and annealed at 573 K, 673 K and 773 K. Cadmium sulfate and sodium sulfide was used as a starting precursor for the preparation of CdS nanoparticles. The XRD results confirmed that major phase of hexagonal structure-CdS along with partial oxidation of CdO and CdSO3 nanoparticles. It reveals that the average crystallite size varies from 25 to 41 nm as annealing temperature increases. The phase and functional group composition was studied through FTIR. The average particle size distribution of CdS nanoparticles is 39, 47, and 49 nm for 573, 673, and 773 K, respectively. The surface morphology of CdS particles revealed the compact crystalline structure. Electrochemical impedance spectroscopy studies showed that the charge transfer resistance is lowered as annealing temperature is increased.

Extraction and Characterization of Keratin from Chicken Feather Waste Biomass: A study

Abstract: Keratins are proteins that form hard fibers, present in wool, horns and hoofs, feathers etc. The feathers consist of up to 10% of total chicken weight. Uncontrolled disposal of feathers from the poultry slaughterhouses industry is troublesome to environment. Primary purification phase is necessary for isolating the keratin from other materials. The present work was conducted to isolate the chicken feathers and to extract the keratin from processed biomass. The purification was conducted by washing with ddH2O, detergents and ether and lastly again with boiled water at (100oC). Reducing agents used were sodium sulfide and sodium sulfite. The precipitates obtained in the form of pellet were washed 2-3 times with ddH2O in order to remove foul smell and residues of sodium sulfide and HCl can be washed properly. To prepare the soluble form sodium hydroxide was added. Among the reducing agents tested Sodium sulfide showed good dissolving power as compared to others. Sodium sulfide with 0.3M and 0.5M concentrations dissolved the chicken feather efficiently. Keratin protein was dialyzed by ddH2O using cellulose membrane (12 MWCO) which retained the protein size ~12 kDa. The concentration of keratin was studied by Bradford method (1.6mg/ml) and physiochemical characterization was done by FTIR and TGA analysis. The presence of alkane, carboxylic acid, amine, thiocarbonyl groups and disulfide bond was confirmed by FTIR analysis. The purified keratin is a promising substrate for the synthesis of cosmetic and pharmaceutical products.

Heavy metal adsorption mineralizing agent for synchronously restoring water body and bottom mud of water body and preparation method of heavy metal adsorption mineralizing agent

Abstract: The invention relates to a heavy metal adsorption mineralizing agent for synchronously restoring a water body and bottom mud of the water body and a preparation method of the heavy metal adsorption mineralizing agent The heavy metal adsorption mineralizing agent is characterized in that straws, lignosulfonic acid, hydroxylapatite, bentonite, active carbon, pulverized lime, sodium sulfide and polyvinyl alcohol are mixed to be prepared into gel; calcination is performed; the particular heavy metal adsorption mineralizing agent with the density being 1015 to 1120g/cm is obtained, wherein the dry substance weight percentage of each ingredient is respectively shown as follows: the dry substance weight percentage of the straws is 45 to 55 percent; the dry substance weight percentage of the lignosulfonic acid is 10 to 20 percent; the dry substance weight percentage of the hydroxylapatite is 5 to 10 percent; the dry substance weight percentage of bentonite is 5 to 10 percent; the dry substance weight percentage of the active carbon is 0 to 5 percent; the dry substance weight percentage of the pulverized lime is 5 to 10 percent; the dry substance weight percentage of the sodium sulfide is 4 to 8 percent; the dry substance weight percentage of the polyvinyl alcohol is 3 to 6 percent

Pollution-free flotation separation method for copper-lead-zinc polymetallic ore

Abstract: The invention discloses a pollution-free flotation separation method for copper-lead-zinc polymetallic ore. The method comprises the steps that crushed raw ore and water are firstly ground according to the ratio of 1:1 till the fineness of materials discharged out of a ball grinding mill is -0.074 mm and reaches 90%-95%, inhibitors, such as lime, sodium sulfide, zinc sulfate and sodium sulfite and a sodium butyl xanthogenate as a collecting agent are added for copper-lead bulk flotation, copper-lead roughing concentrates are ground to be -0.045mm and reach 90%-95%, the inhibitor of zinc sulfate and sodium sulfite and the collecting agent Z-200 are added at low alkalinity to inhibit lead and float copper to achieve copper-lead asynchronous separation, and copper concentrates are obtained through one time of rougher flotation and two times of concentration; after copper-lead separation roughing tailings are subjected to one-time scavenging, lead flotation is carried out, during lead flotation work, lime is added to intensify zinc and sulfur inhibition, sodium butyl xanthogenate serves as the collecting agent, and lead concentrates are obtained through one time of rougher flotation, two times of scavenging and two times of concentration; and lead scavenging tailings return to copper-lead bulk rougher flotation work, and other middlings cyclically return to the last work. The method has the beneficial effects of being environment-friendly, free of pollution, low in production cost and good in separation effect, and copper-lead-zinc efficient separating and comprehensive recycling are achieved.

Lead concentrate and zinc anode mud combined recycling method

Abstract: The invention discloses a lead concentrate and zinc anode mud combined recycling method. The method comprises the steps of (1) performing oxidation leaching on lead concentrate by adopting acid solutions of ferric chloride and sodium chloride, so as to obtain filtrate A; (2) adding sodium sulfate to the filtrate A for lead precipitation reaction, so as to obtain filtrate B; (3) adding zinc anode mud and hydrochloric acid to the filtrate B for manganese leaching reaction, so as to obtain filtrate C; (4) adding sodium sulfide to the filtrate C for refined precipitation reaction, so as to obtain filtrate G; (5) adding sodium hydroxide to the filtrate G for iron precipitation reaction, so as to obtain filtrate H; (6) adding sodium phosphate to the filtrate H for calcium and magnesium precipitation reaction, so as to obtain the filtrate I; (7) adding ammonium bicarbonate to the filtrate I for manganese precipitation reaction, so as to obtain a finished product of manganese carbonate. By using the processing method, the lead concentrate and zinc anode mud combined recycling and the comprehensive recovery and utilization are realized, and the method has good economic benefits, environmental benefits and social benefits.

Neutral Protease Assisted Low-sulfide Hair-save Unhairing Based on pH-sensitivity of Enzyme

Abstract: The mass transfer of protease in hide during enzymaticunhairing was first investigated by fluorescent tracer technique.It was found that the penetration rate of protease in hide wasquite slow, and protease remained on the grain/papillary layereven after removal of hair, which is the main reason whyenzymatic unhairing may cause grain damage or loose grain.But protease could effectively remove epidermis in a short time.From these phenomena, we developed an enzyme assisted lowsulfidehair-save unhairing (EALS unhairing) based onpH-sensitivity of neutral protease activity. To avoid risk of hidedamage, soaked cattle hide (pH 8) was first treated with neutralprotease (20 units/g hide) for 40 min at 22oC to cleave epidermisbut not to unhair, and then 1% lime was immediately added bothfor inactivation of the neutral protease (pH>12) and for hairimmunization. Finally, the hide was completely unhaired byusing 0.8% sodium sulfide with intact hair shaft. The smartlycontrolled action of protease, as well as the synergistic effect ofprotease, lime and sulfide, ensured the complete removal of hairand epidermis with reduced offer of chemicals, and preventedpelts from defects. The crust leather processed by using EALSunhairing had a cleaner grain surface compared with that usingconventional sulfide-lime unhairing. Additionally, the physicalproperties of the leather processed with EALS unhairing werecomparable to those of conventional leather. Sulfide, total solids,suspended solids and chemical oxygen demand in the EALSunhairing effluent were markedly reduced due to a dramaticdecrease in the input of sodium sulfide and lime as well as therecovery of hair.

Calculation of conditional equilibrium in serial multiple precipitation of metal sulfides with hydrogen sulfide stream generated from sodium sulfide: a didactic tool for chemistry teaching

Abstract: Hydrogen sulfide is presented in textbooks as toxic, environmentally unacceptable species, however some positive effects in human metabolism were discovered in the last decades. It is important to offer students also some new information about this compound. As didactic tool in this case may serve serial precipitation of Cd2+, Cu2+, Zn2+, Mn2+ and Pb2+ ions forming various colored sulfides in bubblers with chemically generated hydrogen sulfide stream. This experiment has strong and diverse color effect for enhancing the visual perception to motivate students to understand more abstract and complex information about hydrogen sulfide. It also may be helpful in analytical chemistry courses for conditional precipitation equilibrium teaching and calculations.

Flotation study of oxide zinc ore using cationic-anionic mixed collectors

Abstract: A representative sample of zinc oxide from Dashteh Sefid mine was obtained and then mineral characterization studies were done. The results of mineralogical analysis showed that the main zinc-bearing minerals are smithsonite, hemimorphite and gangue minerals are quartz and dolomite. In the present paper, the effect of important factors including sodium sulfide, collector type (AC and AC/KAX), collector amount, sodium silicate, CMC dosage and frother type (MIBC and pine oil) were investigated. Design of experiment was carried out by the means of Design Expert 7 using Fractional Factorial 26–1. The results indicated that collector type, collector amount, CMC and frother dosage were the most effective factors controlling the zinc flotation recovery. For the zinc grade, it was found that all six parameters play a significant role. The maximum recovery and grade of zinc obtained 97.71% and 10.39% under the following optimum conditions: sodium sulfide, 5935.23 g/t; collector type, AC/KAX; collector amount, 654.09; sodium silicate, 300; CMC dosage, 600; frother type, MIBC. The result of two-stage cleaner flotation showed that zinc grade could be increased up to 16.2% with zinc recovery of 61.39%.

Aqueous Compatible Protocol to Both Alkyl and Aryl Thioamide Synthesis.

Abstract: A broad range of functionalized aryl, hetaryl, and alkyl aldehydes react with N-substituted or N,N-disubstituted formamides and sodium sulfide to form the corresponding thioamides in moderate to high yields.