Barium polysulfide

Barium Polysulfide 50864-67-0 Boron Trichloride 10294-34-5 Butylated Hydroxytoluene 128-37-0... 

Barium sulfide solutions undergo slow oxidation in air, forming elemental sulfur and a family of oxidized sulfur species including the sulfite, thiosulfate, polythionates, and sulfate. The elemental sulfur is retained in the dissolved bquor in the form of polysulfide ions, which are responsible for the yellow color of most BaS solutions. Some of the mote highly oxidized sulfur species also enter the solution. Sulfur compound formation should be minimized to prevent the compounds made from BaS, such as barium carbonate, from becoming contaminated with sulfur. 

The aqueous solution of barium sulfide oxidizes slowly in the air forming elemental sulfur and various anions of sulfur including sulfite, thiosulfate, polysulfides and sulfate. The yellow color of barium sulfide solution is attributed to the presence of dissolved elemental sulfur that results from its slow oxidation in the air. In the presence of an oxidizing agent, barium sulfate is formed. Violent to explosive oxidation may occur when heated with strong oxidants such as phosphorus pentoxide or potassium chlorate. 

The warm solution (60 C) containing ca. 200 g/L barium sulfide is filtered and immediately pumped to the precipitation stage. Further purification is not necessary. Unreacted gangue and heavy metals are collected as insoluble sulfides in the filter cake. The almost clear solution can be stored only for a short period. Longer storage leads to undesirable polysulfide formation. 

Sealants - [ELASTOMERSSYNTHETIC - POLYISOPRENE] (Vol 9) - [SEALANTS] (Vol 21) -acrylics [ACRYLICESTERPOLYMERS - SURVEY] (Voll) -barium compds in [BARIUM COMPOUNDS] (Vol 3) -based on liquid polysulfides [POLYMERS CONTAINING SULFUR - POLYSULFIDES] (Vol 19) -defoamersin [DEFOAMERS] (Vol 7) -fiom fluorosilicones [FLUORINE COMPOUNDS,ORGANIC - POLY(FLUOROSILICONES)] (Volll) -hydrocarbon resins in [HYDROCARBON RESINS] (Vol 13) -lecithin in (LECITHIN] (Vol 15) -organolithiumcmpdsinprdnof [LITHIUM AND LITHIUM COMPOUNDS] (Vol 15) -polysulfide curing [PEROXIDES AND PEROXIDE COMPOUNDS - INORGANIC PEROXIDES] (Vol 18) -propylene oxide in mfg of [PROPYLENE OXIDE] (Vol 20) -PVB m [VINYL POLYMERS - VINYL ACETAL POLYMERS] (Vol 24) -rheological measurements [RHEOLOGICAL MEASUREMENTS] (Vol 21) -from styrenic block copolymers [ELASTOMERS SYNTHETIC - THERMOPLASTIC ELASTOMERS] (Vol 9) -use of dispersants [DISPERSANTS] (Vol 8)... 

Barium sulfide. [CAS 21109-95-5]. BaS. grayish-white solid, fonned by heating barinm sulfate and carbon, reactive with II20 to fonn barium hydrosulfide, Ba(SH)2, solution. The latter is also made by saturation of barium hydroxide solution with H S. Banum polysulfides are formed by boiling barium hydrosulfide witli sulfur. 

Barium Peroxide. The commercial product is a dull yellow powder containing about 90% Ba02 and about 8.5% active oxygen. The principal use is in pyrotechnics, but there are also small uses in the curing of polysulfide rubbers and in the production of certain titanium-aluminum alloys. 

Other fillers which have been found to be satisfactory for use in polysulfide compounds are zinc sulfide, lithopone and barium sulfate. These fillers have the highest specific gravity and are higher in cost, but have been used in special compounds for dental impression and cold molding applications. 

Barium poisonings are uncommon and usually result from accidental contamination of food sources, suicidal ingestion, or occupational inhalation exposure. The water-soluble barium salts (acetate, carbonate, chloride, fluoride, hydroxide, nitrate, and sulfide) are highly toxic, whereas the insoluble salt, barium sulfate, is nontoxic because it is not absorbed. Soluble barium salts are found in depilatories, fireworks, ceramic glazes, and rodenticides and are used in the manufacture of glass and in dyeing textiles. Barium sulfide and polysulfide may also produce hydrogen sulfide toxicity (see p 224). 

The presence of sulfur in polysulfides, polysulfones, and in sulfur-vulcanized rubber can be demonstrated by the following somewhat uncertain test. The sample is heated in dry air (pyrolysis) and the gases formed during this process are bubbled through a dilute barium chloride solution. The presence of sulfur is indicated by a white precipitate of barium sulfate. 

Lead dioxide has traditionally been the preferred curing agent, but it cannot be used in white or light-tint compositions. Other curing agents which have been used are manganese dioxide, tellurium oxide, barium peroxide, calcium peroxide, zinc peroxide, and dibutyl tin oxide. Silane adhesion promoters are often utilized in polysulfide sealants. ... 

Modifications of these formulas called for the use of sodium, potassium, barium, and ammonium sulfides, which were claimed to produce different shades, but almost all sulfide colors are now produced from solutions of polysulfides, which are sold in concentrated form under a number of trade names. 

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