Barium sulfate formation

In this case, the ion-association model predicted that the connate water would require a minimum dilution with boiler feedwater of 15 percent to prevent halite precipitation (Fig. 8.23). The model also predicted that over-injection of dilution water would promote barite (barium sulfate) formation (Fig. 8.24). Although the well produced F1,S at a concentration of 50 mg/L, the program did not predict the formation of iron sulfide because of the combination of low pH and high temperature. Boiler feedwater was injected into the bottom of the well using the downhole injection valve normally used for corrosion inhibitor injection. Injection of dilution water at a rate of 25 to 30 percent has allowed the well to produce successfully since startup. Barite and iron sulfide precipitation have not been observed, and plugging with salt has not occurred. 

The reaction is used for the chain extension of aldoses in the synthesis of new or unusual sugars In this case the starting material l arabinose is an abundant natural product and possesses the correct configurations at its three chirality centers for elaboration to the relatively rare l enantiomers of glucose and mannose After cyanohydrin formation the cyano groups are converted to aldehyde functions by hydrogenation m aqueous solution Under these conditions —C=N is reduced to —CH=NH and hydrolyzes rapidly to —CH=0 Use of a poisoned palladium on barium sulfate catalyst prevents further reduction to the alditols... 

Alkali moderation of supported precious metal catalysts reduces secondary amine formation and generation of ammonia (18). Ammonia in the reaction medium inhibits Rh, but not Ru precious metal catalyst. More secondary amine results from use of more polar protic solvents, CH OH > C2H5OH > Lithium hydroxide is the most effective alkah promoter (19), reducing secondary amine formation and hydrogenolysis. The general order of catalyst procUvity toward secondary amine formation is Pt > Pd Ru > Rh (20). Rhodium s catalyst support contribution to secondary amine formation decreases ia the order carbon > alumina > barium carbonate > barium sulfate > calcium carbonate. 

In humans, inhaled insoluble barium salts are retained in the lung (47,49). Inhalation of high concentrations of the fine dusts of barium sulfate can result in the formation of harmless nodular granules in the lungs, a condition called baritosis (49). Baritosis produces no specific symptoms and no changes in pulmonary function. The nodulates disappear upon cessation of exposure to the barium salt. However, it is possible that barium sulfate may produce benign pneumoconiosis because, unlike barium carbonate, barium sulfate is poorly absorbed (21). 

The formulation of calcium chelate materials is based upon the formation of a low-solubiUty chelate between calcium hydroxide and a sahcylate. Dycal utilizes the reaction product of a polyhydric compound and sahcyhc acid. Other sahcyhc acid esters can be similarly used. Vehicles used to carry the calcium hydroxide, extenders, and fillers may include mineral oil, A/-ethyl- -toluenesulfonamide [80-39-7] and polymeric fluids. The filler additions may include titanium dioxide [13463-67-7] zinc oxide, sihca [7631-86-9], calcium sulfate, and barium sulfate [7727-43-7]. Zinc oxide and barium sulfate are useflil as x-ray opacifying agents to ensure a density greater than that of normal tooth stmcture. Resins, rosin, limed rosins, and modified rosins may serve as modifiers of the physical characteristics in both the unset and set states. 

In a study on the influence of supports on rhodium, the amount of dicyclohexylamine was found to decrease in the order carbon > barium carbonate > alumina > barium sulfate > calcium carbonate. Plain carbon added to rhodium-on-alumina-catalyzed reactions was found to cause an increase in the amount of dicyclohexylamine, suggesting that carbon catalyzes the formation of the intermediate addition product (59). 

Suito, E. and Takiyama, K. (1954) Formation and aging of precipitates. I. Electron microscopic studies of the formation of barium sulfate precipitate. Bull. Chem. Soc. Japan, 27, 121-123. 

The formation of calcium carbonate (CaCOs), calcium sulfate, and barium sulfate scales in brine may create problems with permeability. Therefore it is advantageous that newly made fractures have a scale inhibitor in place in the fracture to help prevent the formation of scale. Formulations of hydraulic fracturing fluids containing a scale inhibitor have been described in the literature [1828]. 

There is considerable potential, therefore, for mineral scale, such as barium sulfate (see the next section), to form during these procedures. The scale may be deposited in the formation, the wellbore, or in production tubing. Scale that forms in the formation near wells, known as formation damage, can dramatically lower permeability and throttle production. When it forms in the wellbore and production tubing, mineral scale is costly to remove and may lead to safety problems if it blocks release valves. 

Two case studies of acute intrusion of barium sulfate into the peritoneal space during barium enema examination of four men showed barium sulfate caused an acute inflammatory tissue response (Kay 1954 Yamamura et al. 1985), and in one case resulted in formation of a fibrous granuloma (Kay 1954). This is an extremely rare mode of entry and not of significant concern for individuals exposed at a hazardous waste site. Increased fluid accumulation in the intestinal lumen of rats was observed after intraperitoneal injection of barium chloride (Hardcastle et al. 1983b, 1985) however, this observation is not significant for individuals exposed at hazardous waste sites because of the route of exposure and because there has been no documentation of this effect occurring in humans following normal exposure routes. 

Barium sulfate is used to visualize the GI tract.105 Barium sulfate should be avoided in a patient with GI obstruction. It is insoluble and nontoxic but is a soluble compound, which is toxic and may lead to death. Constipation may be detected on oral and rectal administration, and is remedied if a large amount of water is given to the patient. A barium sulfate enema causes electrocardiogram abnormalities. Pneumonitis or granuloma formation are reported during accidental aspiration into lungs. Hypersensitivity reactions also have been reported.106... 

This intermediate was alkylated with tert. -butyI-cj-iodohexanoate to the ester 30. Conversion to the acid 31 was achieved by cleavage of the fed.-butylester with trifluoroacetic acid at low temperature. The triple bond was reduced to a trans-double bond and simultanously the benzylether groups had been removed with lithium in ethylamine, under formation of the desired 15-deoxy-7-oxaprostaglandin Fla 32 in crystalline form. The ds-isomer was prepared by first reducing the triple bond of compound 30 with palladium on barium sulfate to 33, removal of the ted. -butylgroup with formic acid to 34 and debenzylation of the acid with lithium in ethylamine to 35. 

The nearly insoluble sulfates occur as minerals these include CaS04 2H20 (gypsum), SrS04, BaS04 (barite), and PbS04. Barium sulfate is the least soluble of the sulfates, and its formation as a white precipitate is used as a test for sulfate ion. 

During the induction period this process continues on the surface of the nucleation site until the critical cluster has collected the next ion to be added triggers nucleation. Crystal growth then can follow. For barium sulfate, La Mer concluded that the slope of the line in Figure 8-1 is six and therefore the nucleation of barium sulfate is a seventh-order reaction overall. The critical cluster is then (Ba" " S04")3, and the addition of the seventh ion, either Ba " or 804 , constitutes the final step of the nucleation process. The question of the number of ions in the critical cluster, however, is by no means settled. Christiansen and Nielsen concluded that for barium sulfate the number is 8. Johnson and O Rourke also concluded that the nucleation rate of this salt is proportional to the fourth power of the concentration. The concept of a small critical nucleus is intuitively satisfying in that the nucleus then requires only a small number of steps for its formation. On the other hand, application of the... 

The rate of aging is strongly influenced by other solutes in solution and thus can be increased or decreased by the presence of excess lattice ions in solution. Barium sulfate ages more slowly in barium ion solution than in sulfate and more slowly in sulfate than in water. The aging of silver chloride is impeded by silver ion, but speeded by chloride ion a similar effect exists for silver bromide. For lead chromate no particular lattice ion effect was noticed. Apparently the rate of aging does not parallel solubility, which is decreased by the common ion effect. Kolthoff and others postulated that the solubility in the adsorbed water layer may be different from that in the bulk of the solution. For example, in the case of silver chloride in the presence of adsorbed chloride ion, the solubility may be increased owing to the formation (Section 7-7) of AgCl2 in the immediate vicinity of the surface. It appears likely that the adsorbed lattice ion also has a pronounced effect on the rate of recrystallization, which is not necessarily parallel with solubility even in the adsorbed water layer. 

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