Showing papers on "Sodium sulfide published in 1993"

Process for sodium sulfide/ferrous sulfate treatment of hexavalent chromium and other heavy metals

Abstract: A process for treating industrial waste water containing hexavalent chromium (Cr+6) and other heavy metals is disclosed which comprises reduction of Cr+6 to trivalent chromium (Cr+3) and the precipitation thereof with other heavy metals by addition of sulfide ion and ferrous ion to the waste stream at a pH of about 7 to 9 under conditions such that sludge production by the process of the invention is substantially less than that characteristic of prior art processes. Polymers are added to the solution to assist flocculation and clarification of the waste stream. More specifically, the invention comprises adding sulfide ion in a sulfide to hexavalent chromium ratio of about 0.7-2.5:1 and adding ferrous ion in a ferrous to hexavalent chromium ratio of about 0.5-5.0:1. The waste stream pH is preferably maintained in the range of about 7.2 to 7.5.

Synthesis and reactivities of a highly strained thiophene with two fused four-membered rings, 1,2,4,5-tetahydrodicyclobuta[b,d]thiophene

Abstract: The successful synthesis of 1,2,4,5-tetrahydrodicyclobuta[b,d]thiophene (1) and its ususually enhanced reactivities because of large ring strain are described. Thus, intramolecular pinacol coupling of diketo sulfide 14, obtainable from 2-bromocyclobutanone and sodium sulfide, with a low-valent titanium reagent affords the thiolane-3,4-diol 15 in 36% yield based on the bromo ketone. After conversion of 15 to the bis-methanesulfonate 16 in 66% yield, the latter was treated with potassium tert-butoxide to give 1 nearly quantitatively as a rather thermally stable, colorless, highly sublimative, nicely crystalline compound. Bromine rapidly adds to 1 to give the tetrabromide 21, revealing its olefinic character. Furthermore, 1 undergoes Diels-Alder reaction with tetracyanoethylene at room temperature to afford an adduct. The Diels-Alder reaction with maleic anhydride at room temperature gives an adduct in the endo-exo isomer ratio 5:1, whereas the reaction with excess maleic anhydride in refluxing benzene produces a bisadduct with loss of sulfur. Similar behaviors of 1 toward N-phenylmaleimide were also observed. Flash vacuum pyrolysis of 1 gave benzo[b]thiophene but not the expected radialene or its superthiophenophane

Activator-frother composition

Abstract: An activator-frother composition of good selectivity which can be used as additional reagent for the flotation of minerals of finely ground sulfide type and as sole reagent in the treatment of flotation tailings, which consists of about 1% to 10% by weight of pine oil, about 10% to 30% by weight of sodium sulfide, about 20% to 40% by weight of sodium bicarbonate. The composition has the advantage of requiring little time of homogenization and conditioning in order to be sufficiently soluble, to be stable within a wide pH range, and not to be contaminating.

Oxidation of white liquor using a packing column

Abstract: A method of producing oxidized white liquor from white liquor in which sodium sulfide is oxidized to sodium sulfate. In accordance with the method, an oxygen containing gas is contacted with the white liquor at a temperature of at least 110° C. and such that the total pressure of oxygen and water vapor is no less than 9.2 atmospheres during the contacting.

Process for the production of alkali metal hydroxides and elemental sulfur from sulfur-containing alkali-metal salts

Abstract: The present invention relates to a process for the production of alkali metal hydroxides, such as caustic soda, and elemental sulfur, characterized in that to an electrochemical cell an aqueous solution of an alkali metal sulfide, e.g., sodium sulfide, is fed in order to cause the following reations to take place: * at the anode Na₂S ---> 2Na⁺ + S + 2e⁻ * at the cathode 2H₂O + 2e⁻ ---> 2OH⁻ + H₂ with the overall reaction being thus the following: Na₂S + 2H₂O ---> 2NaOH + S + H₂. Elemental sulfur, which is insoluble, is recovered from the anodic solution by filtration. The NaOH solution is extracted from the cathodic compartment by means of the addition of water. The concentration of the solution of alkali metal hydroxide obtained is a function of the characteristics of the membrane used. In the disclosed process, the standard potential of the anodic reaction: S²⁻ - 2e = S⁰ is lower than of the corresponding processes which lead to the development of gases (Cl₂, O₂), thereby an adavantageous decrease in cell voltage being made possible.

Production of aromatic sulfide polymer

Abstract: PURPOSE:To obtain, an aromatic polymer having high molecular weight and useful as a heat-resistant resin in high reproducibility by reacting a dihalogenated aromatic compound in an organic solvent with an alkali metal sulfide such as anhydrous NaS produced by the solid-phase conversion dehydration of hydrated NaS crystal. CONSTITUTION:A dihalogenated aromatic compound (e.g. p-dichlorobenzene) is made to react with an alkali metal sulfide in an organic solvent (e.g. N- methylpyrrolidone) in the presence of 0.2-2.5mol of water (based on 1mol of sulfur atom in the reaction system) under agitation while sufficiently replacing the system atmosphere with nitrogen and keeping the reaction temperature at 240 deg.C for 2hr. The obtained slurry is poured into water and the precipitate is separated, washed and dried in a vacuum drier at 80C for a night to obtain the objective aromatic sulfide polymer having high molecular weight and excellent heat-resistance and useful as an electronic parts, automobile parts, etc., in high reproducibility. The alkali metal sulfide to be used in the above process is e.g. anhydrous sodium sulfide produced by the solid-phase conversion dehydration of hydrated sodium sulfide crystal.

Production of aromatic sulfide/sulfone polymer

Abstract: PURPOSE:To economically obtain the subject new amorphous polymer excellent in heat resistance, flame retardancy, mechanical characteristics, etc., by reacting a dihalodiphenyl sulfone with a sulfidizing agent and then reacting the resultant reaction product with a specific dihalo aromatic compound. CONSTITUTION:(A) A dihalodiphenyl sulfone (preferably a 4,4'-dihaloeno derivative such as 4,4'-dichlorodiphenyl sulfone) in an amount of 0.45-0.53mol based on 1mol sulfur in (B) a sulfidizing agent (preferably sodium sulfide pentahydrate, etc.) is initially reacted with the component (B) in an organic solvent (preferably N-methylpyrrolidone, etc.). The resultant reaction product is then reacted with (C) a dihalo aromatic compound (preferably p-dichlorobenzene, etc.) which is a dihalobenzene or a dihalonaphthalene capable of containing a substituent group to afford the objective polymer having units expressed by the formula (-Ar- is phenylene or naphthalene capable of containing a substituent group; -phi- is p-phenylene).

Enhanced thermal and ignition stability azide gas generant intermediates

Abstract: Slurry and spray dried azide-based gas generant intermediates are made having a hydrazoic acid content of less than about 3×10 EXP(-3) M/L, a pH of greater than 8.0 up to about 12.5, and impurity metal ions Ca, Mg, Pb, Fe, Mn and Cu, each below about 25 ppm. These intermediates are made by slurrying powdered ingredients of the azide and oxidizer/reactant in water, wet grinding the slurry and spray drying to form a particulate material which is molded into pellets or tablets which are useful as the gas generant in vehicle crash bags or inflators. The basicity of the water is adjusted to a pH of greater than 8.0 up to about 12.5, preferably about 10, by the addition of a base, such as NaOH, followed by the addition of such solid ingredients as S, MoS2 and NaN3, and preferably the NaN3 is added last, whereby hydrazoic acid production is minimized. The contaminant Ca and Mg ions are minimized by softening the water supplied. Impurity ions are also minimized by being precipitated as non-hazardous compounds by adding such agents as sodium sulfide and tri-sodium phosphate to the slurry. Impurities in the MoS2 feed may be further minimized by chemical leaching purification.

Process for purifying of sodium sulfide

Abstract: The sodium sulfide refining process includes roasting the mixturre of coal and anhydrous mirabilite to form rough soda, then cooling and soaking to obtain concentrated soda liquor; the characteristics are that 4-8 kg deiron agent is added in each cubic meter of said concentrated soda liquor, whose temp. is controlled to 50-100 deg.C, the optimum value is 65-85 deg.C, after stirring, the subsidence time ought to be not less than 4 hrs., then through solid-liquid separation to obtain refined soda liquor, present invention features simple process, less environmental pollution, the product contains not only less iron, but also less sodium carbonate, sodium chloride, sodium thiosulfate, sodium sulfite and other impurities.

Structure of bis(pentamethyldiethylenetriamine)disodium hexasulfide

Abstract: The new sodium sulfide compound, μ-hexasulfido-1κ 2 S 1 ,S 6 :2κ 2 S 1 ,S 6 -bis{[N-(dimethylaminoethyl)-N,N',N'-trimethyl-1,2-ethanediamine-κ 3 N,N',N'']sodium}, [Na(pmdeta)] 2 [S 6 ] (1) [pmdeta=(Me 2 NCH 2 CH 2 ) 2 NMe], was obtained by reacting two equivalents of sodium hydride with elementary sulfur in toluene containing an excess of pmdeta at approximately 238 K. The crystal structure contains a central Na 2 S 2 ring in which both S atoms are part of an S 6 2- residue. In addition, each Na atom is coordinated by a pmdeta molecule

Synthesis of 4- and 6-methyl derivatives of 5,7-dioxo(4h,6h)-1,3-dithiolo[4,5-d]pyrimidine based on methylbarbituric acids, spectroscopic characteristics and acidity constants

Abstract: We have obtained previously unknown 1-methyl- and 1,3-dimethyl-5-diethylaminothiocarbonylthiobarbituric acids by reaction of sodium diethyldithiocarbamate with 5-phenyliodonium betaines of 1-methyl- and 1,3-dimethylbarbituric acids. Cyclization of these compounds upon heating in conc. H2SO4 gives methyl-substituted 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2-diethylimmonium hydrosulfates; the derivative of 1-methylbarbituric acid forms a mixture of 4-methyl- and 6-methyl-substituted compounds (2∶1). We isolated perchlorates of 4-methyl- and 4,6-dimethyl-substituted derivatives in pure form. By treatment of the immonium salt with sodium sulfide or selenide, we obtained 4-methyl- and 4,6-dimethyl-5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2-thiones and 4-methyl-, 6-methyl-, and 4,6-dimethyl-2-selenones. We characterized the isomeric 4- and 6-methyl-substituted selenones by electronic absorption spectra and ionization constants (7.65 and 4.0). The differences in the pK values and in the electronic absorption spectra makes it possible to distinguish the substitution site in N-mono-substituted derivatives of 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine.

Treatment of harmful heavy metal-containing waste

Abstract: PURPOSE:To treat heavy metal-containing waste so as to stabilize and increase the elution suppressing effect of a harmful heavy metal. CONSTITUTION:5-100 pts.wt. of sulfur or sulfur polymer cement(SPC) and 1-30 pts.wt. of a heavy metal sealing stabilizer such as sodium silicate, sodium sulfide or a chelating agent are mixed with 100 pts.wt. of harmful heavy metal- containing waste and the resulting mixture is heated, melted and kneaded at about 120-150 deg.C to be cooled and solidified. Sulfur or SPC is solidified in such a state that the heavy metal in waste particles kneaded in a molten state is incorporated in the polymeric chain of sulfur coagulated at the time of cooling. A heavy metal sealing stabilizer is mixed with molten sulfur or SPC to stabilize a heavy metal as a compd. insoluble in water.

Carbon monoxide reduction of sodium sulfate mixed with sodium titanate

Abstract: The solid state reduction kinetics by carbon monoxide of sodium sulfate mixed with sodium titanate are studied in a thermogravimetric system at 670-750°C. It is found that the reduction of this mixture is much faster than that of pure sodium sulfate. The conversion-time curves of the model mixtures are sigmoidal in shape and well described by the nucleation and growth kinetic model. The activation energy is 420 kJ/mol. The influence of the CO and CO2, concentration, mass fraction of sodium titanate and addition of sodium sulfide catalyst are investigated. Based on the present experiments and literature results, a mechanism is proposed for the CO reduction. Les cinetiques de reductiona l'etat solide par l'oxyde de carbone du sulfate de sodium melange a du titanate de sodium ont ete etudiees dans un systeme thermogravimetrique a 670-750°C. On a observe que la reduction de ce melange etait beaucoup plus rapide que pour le sulfate de sodium pur. Les courbes de temps de conversion des melanges du modele sont de forme sigmoidale et sont bien decrites par le modele de nucletion et de cinetique de croissance. L'energie d'activation est de 420 kJ/mol. On a egalement etudie l'influence de la concentration en CO et en CO2, de la fraction massique de titanate de sodium et de l'addition d'un catalyseur de sulfure de sodium. A partir de ces experiences et des resultats de la litterature scientifique, un mecanisme de reduction du CO est propose.

High sensitivity analysis of sulfur

Abstract: PURPOSE:To rapidly measure a very small amount of sulfur in a sample with high sensitivity and high accuracy by mixing a solution containing sulfur prepared from the sample in a state of a sulfide ion with an acid solution and introducing generated hydrogen sulfide into plasma CONSTITUTION:A 025N aqueous sodium hydroxide solution containing sodium sulfide is supplied from piping 1a at predetermined flow velocity and a 1N aqueous hydrochloric acid solution is supplied from piping 1b at predetermined flow velocity by a peristaltic pump and both solutions are allowed to meet with each other in T-piping 2 Argon gas is supplied from piping 3 at predetermined flow velocity and the liquid mixture is guided to a triple-wound Teflon reaction coil 4 held to predetermined temp to generate hydrogen sulfide under stirring The resulting gas-liquid mixture is subjected to gas-liquid separation by a gas-liquid separator 5 and argon gas is supplied at predetermined flow velocity from piping 6 and the separated hydrogen sulfide gas is guided to an inductive coupling plasma emission analyzer 8 through piping 7 Sulfur is quantified on the basis of the emitted light of sulfur by the analyzer 8

Carbonation conversion of aqueous sodium sulfide to hydrogen sulfide

Abstract: In order to control SO 2 emissions, one option is to win metal from sulfide ores under reducing conditions. In this direct reduction process with soda ash as the flux, one of the key steps is the recovery of sulfur from Na 2 S. The objective of the present study is to investigate the kinetics of the carbonation conversion of aqueous Na 2 S to gaseous H 2 S for the purpose of elemental sulfur production. In a reactor which is characterized by continuous operation with respect to gas flow, but batchwise for the liquid phase, three distinct reaction periods were observed. In the second period which is of practical importance, the reaction is first order with respect to bisulfide concentration in solution and first order with respect to CO 2 partial pressure

Production of polyphenylenesulfide composition

Abstract: PURPOSE:To obtain the title composition capable of providing moldings improved in electric, mechanical and surface characteristics by adding a water soluble compound consisting essentially of SiO2 and l2O3 to a reaction system when an aromatic polyhalogen compound is reacted with a sulfur source. CONSTITUTION:When an aromatic polyhalogen compound (preferably a compound containing >=70mol% p-or m-dichlorobenzene unit) is reacted with a sulfur source (e.g. sodium sulfide) in an organic polar solvent (preferably N- methylpyrrolidone), an aqueous solution of a water soluble compound (preferably Na2SiO3, Na Al2O4, etc.) consisting mainly of SiO2 and/or Al2O3 is added to the reaction system to provide the objective composition containing 0.0002-1.5wt.% SiO2 and/or Al2O3 as Si and/or Al in the resultant polymer.

Removal of mercury from han solutions

Abstract: A process for the removal of mercury from industrial waste streams is disclosed wherein the waste stream is a nitrate based solution that has been decomposed by the addition of hypochlorite. The method involves adding a reducing agent to reduce the hypochlorite and/or adjusting the pH by the use of a strong acid to less than about 2.0, converting any residual chlorine to a soluble unreactive salt, adding a soluble precipitating agent, such as sodium sulfide, to the solution in a ratio to the mercury present of greater than 1:1 to about 2:1 to precipitate out the mercury as a mercury compound. The solution is then filtered to remove the precipitated mercury compound.