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Showing papers on "Sodium sulfide published in 2001"


Journal ArticleDOI
TL;DR: A sensitive and reliable method was developed for the determination of hydrogen sulfide and acid-labile sulfur (ALS) in animal tissues using gas chromatography with flame photometric detector (GC-FPD) and ion chromatography (IC).

88 citations


Journal ArticleDOI
TL;DR: The mixing of waste solution obtained from chrome tanning process and waste solution derived from liming of bovine leather was investigated and indicated that the mixing of the corresponding waste solutions yields the mixture effluents that are ecologically acceptable.

55 citations


Journal ArticleDOI
TL;DR: In this paper, Trialkylphosphine oxide (alkyl = ethyl or octyl) is chosen as a surfactant to passivate the surface of CdS nanoparticles.
Abstract: The general study of crystal growth of spherical-like nanoparticles involves monitoring the kinetics during the progress of the reaction. In the case of cadmium sulfide (CdS), cadmium acetate and sodium sulfide are employed as starting reagents that are dissolved in different solvents (ethylene glycol, glyme, diglyme, and trioctylphosphine) to study the solvent effect on monomers, nucleation rates, and the quality of the seeds. Trialkylphosphine oxide (alkyl = ethyl or octyl) is chosen as a surfactant to passivate the surface of CdS nanoparticles. We propose a kinetic approach model to illustrate the unreported time-evolved crystal growth mechanism observed in this case. An experimental value for the diameter of critical volume (Vc), a nanosized volume with a relative minimum surface-volume tension and considered a temporal stable stage (r = 5.7 nm in this case), is derived from transmission electron microscopy images. The size of the nanoparticles made by this synthesis route is tunable by variation of t...

53 citations


Patent
20 Dec 2001
TL;DR: In this paper, an apparatus and process for extracting sulfur compounds from a hydrocarbon stream is described, where a prewash section for converting hydrogen sulfide to sodium sulfide by reaction with an alkali such as caustic communicates with an extractor section disposed directly above the prewash.
Abstract: Described is an apparatus and process for extracting sulfur compounds from a hydrocarbon stream. A prewash section for converting hydrogen sulfide to sodium sulfide by reaction with an alkali such as caustic communicates with an extractor section disposed directly above the prewash section for converting mercaptans to mercaptides by reaction with alkali. Hydrocarbon product exits the extractor section through a coalescer that prevents alkali from exiting with the hydrocarbon product stream.

37 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of a concentration of sodium sulfide, pH, temperature, and electrical potential on the corrosion behavior of silver was investigated using Tafel plots and potentiodynamic polarization.
Abstract: Corrosion of silver and gold in sulfur-containing environments has been an industrial problem. The current study is concerned with the corrosion reaction behavior of silver in sodium sulfide solutions. An electrochemical investigation of silver corrosion has been carried out using a potentiostat, and the resulting corrosion products have been identified with the help of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The effect of a concentration of sodium sulfide, pH, temperature, and electrical potential on the corrosion behavior of silver was investigated using Tafel plots and potentiodynamic polarization. The corrosion products under the conditions studied were found to be mainly silver sulfide and occasionally silver oxide. The corrosion rate was found to be positively influenced by both the pH of the solution and the concentration of sodium sulfide.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrated feasibility for the catalysis of the sodium sulfide reduction of methylviologene (MV2+) in aqueous solution using cupric sulfide nanoparticles.
Abstract: Feasibility was demonstrated for the catalysis of the sodium sulfide reduction of methylviologene (MV2+) in aqueous solution using cupric sulfide nanoparticles. The catalytic activity of the nanoparticles depends on their size. The basic features were found for the formation of the MV+· radical–cation in the reduction of MV2+ by HS− anions in the presence of CuS nanoparticles as the catalyst. This is an equilibrium reaction.

31 citations


Journal ArticleDOI
TL;DR: In this paper, the separation of lead from zinc in alkaline zinc solution, in leaching solutions of EAF dusts, and in oxidized zinc ores by sodium sulfide precipitation was studied.
Abstract: Zinc and lead are usually concomitantly present in Zn-Pb ores and solid wastes, such as electric arc furnace (EAF) dusts. One of the treatment methods is to extract zinc and lead from the ores and wastes by an alkaline leaching process if applicable. The selective and quantitative separation of lead from zinc is an important step in these processes. In this work, the separation of lead from zinc in alkaline zinc solution, in leaching solutions of EAF dusts, and in oxidized zinc ores by sodium sulfide precipitation was studied. When the weight ratio of sodium sulfide (average molecular weight 222) added to the lead present in alkaline solution was over 1.8–2.0 (molar ratio approximately 1.5–1.7), lead could be separated selectively and quantitatively, while the zinc remained in the solution without concomitant loss. The residues from the precipitation step were identified as mixtures of PbS and Na2Pb(OH)2S, with PbS being the predominant compound.

25 citations


Journal ArticleDOI
TL;DR: In this article, the results of acid leaching of gold, antimony, and tin from the electrorefined solid waste were investigated and the parameters affecting the leaching process such as acid concentration, shaking time, temperature, chlorine gas and pulp density were evaluated.

21 citations


Journal ArticleDOI
TL;DR: In this article, a novel heavy metal immobilization by mixing with additives of asphalt, sulfur and sodium hydroxide was proposed, where fly ash was mixed with each additive by using a bi-axial kneader heated at 403 K.
Abstract: The present paper is concerned with a novel heavy metal immobilization by mixing with additives of asphalt, sulfur and sodium hydroxide. To immobilize heavy metals, fly ash were mixed with each additive by using a bi-axial kneader heated at 403 K. Then the dissolution test was carried out based on the Japan Environment Agency notification No. 13. Seven samples of fly ash discharged from the melting process of MSW incineration fly ash were employed. The present immobilization of heavy metal were considered to consist of the conbination of the following two advantages; (1) common advantage of asphalt solidification, (2) additional advantage of low solubility by metal sulfuration. Results of the experiment show that the lead concentration in the eluted solution of the treated sample satisfied Japan's lead emission standard of 0.3 mg/l. It was considered that sodium sulfides, which were produced from the reaction of sulfur and sodium hydroxide, react with heavy metals to form insoluble metal sulfides. The minimum amounts of sulfur and sodium hydroxide needed to achieve the allowable limit had a linear relationship with the heavy metal content in fly ash.

15 citations


Patent
20 Dec 2001
TL;DR: In this article, an apparatus and process for extracting sulfur compounds from a hydrocarbon stream is described, with a prewash section for converting hydrogen sulfide to sodium sulfide by reaction with an alkali such as caustic acid.
Abstract: Disclosed is an apparatus and process for extracting sulfur compounds from a hydrocarbon stream. A prewash section for converting hydrogen sulfide to sodium sulfide by reaction with an alkali such as caustic communicates with an extractor section disposed directly above, the prewash section for converting mercaptans to mercaptides by reaction with alkali. Hydrocarbon product exits the extractor section through a coalescer that prevents alkali from exiting with the hydrocarbon product stream.

14 citations


Journal ArticleDOI
TL;DR: In this article, the effect of changing the leaving group, and changing the solvent of reaction, on the formation of an unsymmetrical furan derivative has been investigated, and the desired compound could be synthesised in good yields from the xanthate 9 using a radical-mediated procedure.

Journal ArticleDOI
TL;DR: In this article, a mild, selective, and rapid replacement of an N-methyl group of tertiary amines with other alkyl groups via a simple one-pot procedure is described.
Abstract: The paper describes a mild, selective, and rapid replacement of an N-methyl group of tertiary amines with other alkyl groups via a simple one-pot procedure. This transformation is easily achieved by preparation of the appropriate quaternary ammonium salt in sulfolane and in situ treatment with sodium sulfide or potassium thioacetate. The protocol is successfully applied to the transformation of dihydrolysergol, dextromethorphan and laudanosine (as models of ergot and opium N-methyl alkaloids) into various N-alkyl congeners.

Patent
29 Nov 2001
TL;DR: In this article, the authors present a process for the preparation of R-lipoic acid and R-dihydrolipoic acids in methanol, where the sulfur is present in a molar excess over the sodium sulfide trihydrate, and a kit which comprises the solution according to the invention.
Abstract: The present invention relates to a process for the preparation of R— and S-lipoic acid and R— and S-dihydrolipoic acid comprising (a) reaction of where MS is SO 2 —R′ and R and R′ independently of one another are C 1 -C 6 -alkyl, C 3 -C 8 -cycloalkyl, C 3 -C 8 -cycloalkylalkyl, aryl or aralkyl, with sodium sulfide and sulfur in methanol. The invention especially relates to processes for preparing pure R— or S-dihydrolipoic acid, which is either used directly or processed further to give R— and S-lipoic acid. The process also serves for the production of pharmaceuticals. The present invention further relates to a solution of sodium sulfide trihydrate and sulfur in methanol, the sulfur being present in a molar excess over the sodium sulfide trihydrate, and a kit which comprises the solution according to the invention.

Journal ArticleDOI
TL;DR: In this article, the physical chemistry of the Na2O-MoO3 system was investigated using a high-temperature electrochemical cell with Na, β-alumina as the solid electrolyte.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the stress corrosion cracking behavior of α-Al bronze in 3.4% NaCl with sodium sulfide contaminations under open-circuit potentials, as well as at different applied potentials using the constant slow strain rate technique.
Abstract: The stress corrosion cracking (scc) behaviour of α-Al bronze was investigated in 3.4% NaCl with sodium sulfide contaminations under open-circuit potentials, as well as at different applied potentials using the constant slow strain rate technique. The susceptibility of α-Al bronze towards stress corrosion cracking has been found to increase with an increase in sulfide ion concentration and in anodic potentials. The increase in sulfide ions in polluted saline water resulted in a reduction in the maximum stress (σ max). The results support film rupture and anodic dissolution at slip steps as the operating mechanism of the stress corrosion cracking process.

Patent
12 Sep 2001
TL;DR: In this paper, the authors used polyhydrate sodium sulfide and p-dichlorobenzene as raw material to produce polyphenylene sulfide (PPS) monomer.
Abstract: The present invention adopts polyhydrate sodium sulfide and p-dichlorobenzene as raw material, and utilizes the processes of dehydrating sodium sulfide and polycondensation to produce polyphenylene sulfide (PPS) monomer. It is characterized by that in the course of dehydration of polyhydrate sodium sulfide the polyhydrate sodium sulfide and NMP solution are heated in reactor to produce azeotropism at 180-220 deg.C so as to make crystal water of polyhydrate sodium sulfide be carried out with vapour phase. Said invention has no need of special dehydration equipment, and the temp. rising for dehydration is identical to the temp. rising direction of next operation for adding p-dichlorobenzene to implement polycondensation reaction, so it can prevent extra energy consumption.

Patent
08 May 2001
TL;DR: For purifying an iron(II) salt solution contaminated with nickel ions and lead ions, the hyperstoichiometric addition of sodium sulfide or sodium hydrogen sulfide in the acid range has proved itself as suitable when a residence time in the order of one hour is adhered to before the sulfides are removed by filtration.
Abstract: For purifying an iron(II) salt solution contaminated with nickel ions and lead ions, the hyperstoichiometric addition of sodium sulfide or sodium hydrogen sulfide in the acid range has proved itself as suitable when a residence time in the order of one hour is adhered to before the sulfides are removed by filtration. The residual contents are equal to less than 30 mg per liter for nickel and less than 7.5 mg per liter for lead.

Patent
16 Mar 2001
TL;DR: In this paper, a water solution of lead nitrate is infiltrated into a substrate made of a porous material, and liquid drops of a liquid solution of sodium sulfide, which is charged into a ink cartridge of a minute nozzle, are sprayed onto the substrate from the minute nozzle.
Abstract: A water solution of lead nitrate is infiltrated into a substrate made of a porous material, and liquid drops of a water solution of sodium sulfide, which is charged into a ink cartridge of a minute nozzle, are sprayed onto the substrate from the minute nozzle The lead component from the lead nitrate water solution and the sulfur component from the sodium sulfide water solution are synthesized directly on the substrate, and thus, a thin film made of lead sulfide is formed on the substrate

Book ChapterDOI
01 Jan 2001
TL;DR: Sodium sulfate is known as an industrial chemical that is often called "salt cake" based upon its former "synthetic" source of reacting salt with sulfuric acid as discussed by the authors.
Abstract: This chapter focuses on the application of sodium sulfate. Sodium sulfate is known as an industrial chemical that is often called “salt cake” based upon its former “synthetic” source of reacting salt with sulfuric acid. It has a large number of uses, but as has happened before, this usage pattern has changed dramatically since the early to mid-1970s. Sodium sulfate is used as a filler or substrate in many powdered, granular, or solid detergent formulations. In North America (Canada, the United States, and Mexico), the average box of laundry detergent in the 1990s contained 20-25% sodium sulfate, and some formulas contained up to 50%. Sodium sulfate is an excellent diluent and standardizing material, providing good flow properties and slightly enhancing the detergent efficiency by stabilizing the colloidal properties of the removed dirt or soil. The major use of sodium sulfate in this application depends upon the “big box” powdered detergent market, and this form of cleaning agent sales has many competitors. Sodium sulfate is used in many applications for the dyeing of textiles. A number of other chemicals are made from sodium sulfate—such as sodium sulfide (Na2S).

Patent
20 Aug 2001
TL;DR: In this article, a manufacturing method of a regenerated cellulose fiber using rice-straw is provided, which is characterized by preventing environmental pollution, manufacturing the fiber economically and enhancing usability and value added.
Abstract: PURPOSE: A manufacturing method of a regenerated cellulose fiber using rice-straw is provided, which is characterized by preventing environmental pollution, manufacturing the fiber economically and enhancing usability and value added. CONSTITUTION: The regenerated cellulose fiber is obtained by a process containing the steps of: grinding the rice-straw to make it particle; cooking the particle in dilute acid for 50-80minutes, followed by dewatering and washing; cooking with sodium hydroxide and sodium sulfide for 90-120minutes, followed by dewatering and washing; extracting pulp ingredient; manufacturing melting pulp which is bleached and increased a-cellulose content with a bleaching agent and sodium hydroxide; and then dissolving the melting pulp with N-methyl mopolyn N-oxide/H2O solvent system, followed by spinning.

Patent
15 Aug 2001
TL;DR: In this paper, the anhydrous sodium sulfide crystal was obtained by using coal powder and adopting sodium sulfate reduction process to prepare the solution, removing impurity and crystallizing to obtain a high purity and uniform granules.
Abstract: The preparation method of anhydrous sodium sulfide crystal includes the following steps: adding adjuvant into coal powder and adopting sodium sulfate reduction process to prepare sodium sulfide solution, removing impurity and crystallizing to obtain sodium sulfide crystal containing 9 crystal waters or 5.5 crystal waters, then under the condition of reduced pressure heating and drying. It is characterized by that the drying temp. of close related to pressure, so that it can prevent aqua compound from producing condensation or adhering to the drier. The anhydrous sodium sulfide crystal obtained by using said invented method features high purity, large specific surface area and uniform granules, and can completely meet the requirements for quality of anhydrous sodium sulfide when the polyphenylene thioether is synthesized.

Patent
24 Jan 2001
TL;DR: An oligomeric conjak-glucomannan-propyl aldehydate disulfate was used as a broad-spectrum fungus disinfectant for rice hypochnus or cotton scorch.
Abstract: An oligomeric conjak-glucomannan-propyl aldehydate disulfate as broad-spectrum fungus disinfectant for rice hypochnus or cotton scorch is prepared from oligomeric conjek-glucomannan aldehydic acid (molecular wt. below2000) which is prepared from refined conjak starch through enzymolysis, oxidation and degradation, through the process of dual esterifying reaction with epoxypropane and formamide-sodium thiosulfate, and them dual sulfurizing with sodium sulfide and hydrochloric acid or oxalic acid. It has the characteristic peak and 9.01% of sulfur content.

Patent
Henry J. Barda1
27 Nov 2001
TL;DR: In this article, a stabilizer composition for polyvinyl chloride was proposed, which can be formed by reacting a mixture of monoalkyltin trichloride and dialkyltin dichloride with at least one carboxylic acid, such as 2-ethylhexanoic acid, and 2-mercaptoethanol, in the presence of base.
Abstract: A stabilizer composition, suitable for use in polyvinyl chloride compositions, can be formed by reacting a mixture of monoalkyltin trichloride, such as butyltin trichloride, and dialkyltin dichloride, such as dibutyltin dichloride, with at least one carboxylic acid, such as 2-ethylhexanoic acid, and 2-mercaptoethanol, in the presence of base, followed by reaction of the resulting product with a sulfide reagent, such as sodium sulfide. The final composition comprises a complex mixture of alkyl tin carboxylates and/or mercaptides, and of monoalkyltin sulfides and dialkyltin sulfides.

Patent
23 Oct 2001
TL;DR: In this article, a method for manufacturing an anatase titanium dioxide photocatalyst using nonporous oxide particles as a support is provided to reduce production cost by depositing titanium dioxide powder of 10-20nm on the surface of economical non-porous oxide support such as silica/alumina under accurately controlled coating/heat treatment conditions.
Abstract: PURPOSE: A method for manufacturing an anatase titanium dioxide photocatalyst using nonporous oxide particles as a support is provided to reduce production cost by depositing titanium dioxide powder of 10-20nm on the surface of economical nonporous oxide support such as silica/alumina under accurately controlled coating/heat treatment conditions. CONSTITUTION: The manufacturing method of titanium dioxide photocatalyst comprises the processes of (i) dispersing nonporous oxide particles such as silica/alumina in 0.01-1.0 M of a diluted solution of titanium compound such as titanium tetrachloride(TiCl4), titanium sulfate(Ti(SO4)2) or TNBT((C4H9O)4Ti); (ii) dropping 0.1-10.0 M of precipitant such as hydrazine, sodium sulfide, formalin, sodium hydroxide or ammonium bicarbonate with stirring the solution so as to form titanium hydroxide on the surface of the nonporous oxide particle; (iii) isolating the nonporous oxide particle being formed with titanium hydroxide coating from the solution, followed by rinsing operation; (iv) drying it at 110deg.C for 24hrs; and then (v) heat-treating the titanium hydroxide for oxidation in the temperature range of 300 to 700deg.C for 1-10hrs under a temperature elevation rate of 5 to 50deg.C/min.

Dissertation
01 Jan 2001
TL;DR: In this article, the Ginstling-Brounshtein product-layer diffusion controlled model was used to investigate the reaction between M113O4 and Na2CC>3 with 1:1 stoichiometry.
Abstract: Manganese oxide, as Mn3CU, was investigated as a direct causticizing agent. The reaction between M113O4 and Na2CC>3 was found to occur with 1:1 stoichiometry. The reaction mechanism is well described by the Ginstling-Brounshtein product-layer diffusion controlled model. In the solid state, from 650 850°C, the activation energy is 206 kJ/mol; with molten N a 2 C 0 3 , from 850 950°C, the activation energy is 174 kJ/mol. An increase in the Mn 3 04 particle size reduces the reaction rate, while excess Mn 3 04 in the reaction mixture increases the rate of N a 2 C 0 3 conversion. Hydrolysis of the direct causticizing product forms a caustic solution, with neither the direct causticizing nor hydrolysis reactions being equilibrium-limited. Na 2 S has a negative impact on the direct causticizing reaction in that the Na2S is oxidized to N a 2 S 0 4 while the Mn 3 04 is reduced to MnO. Introduction One goal of pulp mill chemical recovery is to convert N a 2 C 0 3 into NaOH for reuse in the digester. The traditional CaO-based chemical recovery process is represented by the following chemical equations. Equation 1 CaO + H20=> Ca{OH)2 Equation 2 Na2 C03 + Ca{OH)2 <=> INaOH + CaC03 Equation 3 CaC03 => CaO + C02 The reaction in Equation 2 is an equilibrium-limited reaction. In practice, the conversion of sodium carbonate to sodium hydroxide ranges from 80 to 90%, depending on white liquor total titratable alkali[l]. The remaining unconverted sodium carbonate is part of what is known as deadload in the Kraft liquor cycle. The sodium carbonate does not participate in the pulping reaction and is detrimental because additional energy is

Patent
12 May 2001
TL;DR: In this article, a process for the production of polysulfone having an average sulfur chain length of less than 4 and an iodine color number of no greater than 10 mg iodine/100 ml is described.
Abstract: Production of yellow bis-(3-(triethoxysilyl)-propyl)polysulfane (average sulfur chain length less than 4 and iodine color number no greater than 10 mg iodine/100 ml) comprises mixing neutral chloropropyltriethoxysilane with chloropropyltrichlorosilane and reaction with sodium sulfide and sulfur, disodium tetrasulfide and Nas2S or disodium trisulfide and Na2S in ethanol. A process for the production of yellow bis-(3-(triethoxysilyl)-propyl)polysulfone having an average sulfur chain length of less than 4 and an iodine color number of no greater than 10 mg iodine/100 ml comprises mixing neutral chloropropyltriethoxysilane with chloropropyltrichlorosilane followed by reaction with sodium sulfide (Na2S) and sulfur, disodium tetrasulfide (N2S4) and Nas2S or disodium trisulfide (Na2S3) and Na2S in ethanol.

Patent
30 Jan 2001
TL;DR: In this paper, a negative electrode material with high energy density and cycle characteristics equivalent to those of the existing material at a low cost was provided by utilizing a material containing ZnS as the negative electrode for a nonaqueous lithium secondary battery.
Abstract: PROBLEM TO BE SOLVED: To provide a negative electrode material with high energy density and cycle characteristics equivalent to those of the existing material at a low cost by utilizing a material containing ZnS as the negative electrode material for a nonaqueous lithium secondary battery. SOLUTION: As a studied result of the negative electrode material of a nonaqueous secondary batter of low cost and high quality, ZnS is found as the optimum material. ZnS is obtained by bubbling hydrogen sulfide in an aqueous solution containing zinc ions or adding a water-soluble sulfide such as sodium sulfide or ammonium sulfide to obtain a precipitate of zinc sulfide, washing, and then drying. The ZnS is baked in nonoxideizing atmosphere to be convert into β-type or α-type crystallinity. When this ZnS is used as the negative electrode material, doping/undoping of Li ions is conducted smoothly, and battery characteristics are enhanced. Both the αor β types can be used as the negative electrode active material.

Patent
21 Sep 2001
TL;DR: In this paper, a method for extracting the highly pure collagen from the sharkskin was proposed, which is used to extract the scales from the washed sharkskin and extract the collagen.
Abstract: PROBLEM TO BE SOLVED: To provide a method for treating sharkskin capable of removing scales easily without denaturation of collagen, and further to provide a method for producing the collagen by which the highly pure collagen is obtained from the sharkskin. SOLUTION: This method for producing the collagen comprises treating the sharkskin with sodium sulfide or sodium hydroxide, treating the resultant sharkskin with slaked lime, washing the treated sharkskin with water, treating the washed sharkskin with ammonium sulfate and sodium chloride, soaking the resultant sharkskin in hydrochloric acid or acetic acid, and an aqueous solution of sodium chloride, washing the soaked sharkskin with the water, soaking the washed shark skin in the water, removing the scales from the washed sharkskin, and extracting the collagen from the resultant sharkskin.

Patent
20 Dec 2001
TL;DR: In this article, a funnel formed on the surface of stirred melt is formed to give double copper-sodium sulfide having lower solubility in liquid lead than sodium sulfide.
Abstract: nonferrous metallurgy. SUBSTANCE: sodium hydroxide is admixed to molten lead at 340-370 C in proportion 0.2-0.3% of the weight of lead. Thereafter, 0.03-0.06% sodium sulfide and simultaneously 0.05-0.1% elementary sulfur are introduced into funnel formed on the surface of stirred melt to give double copper-sodium sulfide having lower solubility in liquid lead than sodium sulfide. The latter emerges on the surface of metal and is removed after each portion of sulfur-containing reagents admixed to melt. Sulfur-containing reagents are added 1 to 4 times depending on content of copper in initial material. Residual content of copper in lead is equal to or below 0.001%. EFFECT: provided fine decopperization of lead within sufficiently wide temperature range in melt containing no tin and silver. 1 tbl

Patent
22 Mar 2001
TL;DR: In this article, a method of preparing anhydrous sodium sulfide having an Na 2 S content of at least 98 wt %, by drying hydrous Ss having a water content of 35 to 45%, provided as a solid or in liquefied form, was presented.
Abstract: A method of preparing anhydrous sodium sulfide having an Na 2 S content of at least 98 wt %, by drying hydrous sodium sulfide having a water content of 35 to 45%, provided as a solid or in liquefied form, by intensively kneading and mixing hydrated sodium sulfide at an elevated temperature and pressure to thereby liquify said hydrated sodium sulfide and obtain the anhydrous sodium sulfide.