Strontium sulfate, reduction

Finely powder 50 g. of celestite (or commercial strontium sulfate) and mix it with 20 g. of powdered charcoal. Pack the mixture into an earthenware crucible of as thin walls as possible and heat at the highest temperature of the furnace for about 2 hr. Allow the crucible to cool and test a small portion with dilute hydrochloric or nitric acid. If the residue is chiefly carbon, the reduction is successful if a large amount of insoluble... 

Some of the procedures outlined below have been described previously. " They are designed for the preparation of phosphors that are to be used for quantitative studies of luminescence. Details are presented for the preparation of strontium nitrate, strontium chloride, strontium sulfate, and strontium selenite in a state of high purity for the reduction of the sulfate to the sulfide and the selenite to the selenide and for the conversion of the sulfide and the selenide into typical infrared-sensitive phosphors. 

Strontium - Strontium sulfate (SrS04) has a minimum solubility in 40% phosphoric acid. SrS04 forms a scale in the heat exchangers of phosphoric add concentrators. An extremely thin film of this precipitate causes pronounced reductions in the capacities of such units 137]. 

Strontium and lanthanides (rare earths), found in igneous rocks, inhibit rehydration of the hemihy-drate to gypsum, which can cause problems in certain phosphoric acid processes. Moreover strontium causes problems in the concentration sections because strontium sulfate has a minimum solubility in 40% P2O5 acid. An extremely thin film of SrS04 causes a very pronounced reduction in the capacity of the concentration unit. 

Selective Reduction. In aqueous solution, europium(III) [22541 -18-0] reduction to europium(II) [16910-54-6] is carried out by treatment with amalgams or zinc, or by continuous electrolytic reduction. Photochemical reduction has also been proposed. When reduced to the divalent state, europium exhibits chemical properties similar to the alkaline-earth elements and can be selectively precipitated as a sulfate, for example. This process is highly selective and allows production of high purity europium fromlow europium content solutions (see Calcium compounds Strontiumand strontium compounds). 

The removal of inorganic salts from reaction mixtures afforded by polymeric materials may be simply and effectively accomplished by dialysis,166 178 after decomposition of remaining periodate with ethylene glycol130 131 or butylene glycol. 161 170 Alternatively, the iodate and periodate ions may be removed as such, or after reduction to free iodine. The iodate and periodate ions have been effectively precipitated by means of sodium carbonate plus manganous sulfate,6 or by lead dithionate,191 barium chloride,24 192 193 strontium hydroxide194 202 or barium hydroxide,203 204 lead... 

Palladium catalysts resemble closely the platinum catalysts. Palladium oxide (PdO) is prepared from palladium chloride and sodium nitrate by fusion at 575-600° [29,30]. Elemental palladium is obtained by reduction of palladium chloride with sodium borohydride [27, 31], Supported palladium catalysts are prepared with the contents of 5% or 10% of palladium on charcoal, calcium carbonate and barium sulfate [32], Sometimes a special support can increase the selectivity of palladium. Palladium on strontium carbonate (2%) was successfully used for reduction of just y, (5-double bond in a system of oc, / , y, (5-unsaturated ketone [ii]. 

If the free energy changes for the reduction of the sulfate to make H2S rather than SO2 had been considered in this analysis, the oxides of several more elements would have been included in the boxed-off area of appropriate materials. From past practice, however, it is known that oxides of calcium, strontium and lithium, for instance, are not as effective. An appropriate future area of research would be to investigate those materials more thoroughly. 

Mixing of unlike brines can cause the precipitation of sulfates of barium, strontium, and calcium. This hard scale, which is a nuisance in oilfield flow lines, often can be explained by leaky casing. Soft scale, composed of calcium carbonate, usually is caused by the loss of dissolved carbon dioxide from the brine during pressure reduction. 

In contrast to strontium and osmium isotopes, the isotopes of sulfur are strongly fractionated by biological processes, particularly during the dis-similatory bacterial reduction of sulfate to sulfide. The laboratory results for this step are anywhere from +4 to —46%o (CDT), but even larger fractionations have been observed in natural systems (Harrison and Thode, 1958 Chambers and Trudinger, 1979 Habicht and Canfield, 1996). 

Strontium Snlfide. SSr mol wt 119.7O. s 26.79%, Sr 73,21%. SrS. The article of commerce contains 65-75% SrS. Strontium sulfide made by reduction of the sulfate is not luminous the. luminous sulfide is prepared by heating strontium hydroxide with sulfur. 

Sulfur oxides and nitrogen oxides may be removed from combustion gases by various processes. One of the cost-effective and efficient methods involve dry scrubbing of SOx and NOx over lanthanide-oxygen-sulfur compounds (Jalan and Desai 1992). Cerium sulfate is found to be an effective catalyst toward the reduction of NOx by ammonia. A combined removal of NOx and SOx has been achieved using cerium oxide doped with strontium oxide, lanthanum oxide, calcium oxide, or cerium sulfate. 

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