Alkali breakdown

Alkali breakdown is usually carried out as a simple batch operation in mild-steel, cast iron or stainless-steel vessels. The reaction products may assume the form of a viscous paste and suitable agitation is necessary to maintain intimate mixing. The design of stirrer system is simpler than for breakdown by concentrated sulphuric acid since corrosive fumes are not present to attack bearings or motors, etc., and corrosion of the stirrer blades and vessel by the reactants or products is also much less serious. A simple gate stirrer of mild steel or stainless steel is usually satisfactory. The reaction vessel may require to be tipped if the products are solids or viscous pastes, but in other circumstances a bottom outlet might be satisfactory. 

Rock monazite, obtainable from South Africa, contains a few per cent of the mineral apatite (calcium phosphate) together with a little iron phosphate impurity. The apatite in particular does not respond to the sodium hydroxide breakdown procedure to the same extent as thorium and rare earth phosphates. Consequently, the oxide product after washing still contains a quantity of phosphate about equal to the weight of thorium present. This is too high for passing to the final solvent purification stage and it is therefore necessary to eliminate apatite before the alkali breakdown stage. Removal is accomplished by a pretreatment process " in which... 

The American Battelle Memorial Institute TBP extraction process resembles the U.K. process a little more closely. In this, a feed solution made by the alkali breakdown route is extracted into a solvent mixture of TBP and solvent naphtha. Thorium is selectively backwashed with dilute nitric acid, and the uranium backwashed in a separate extractor with water. 

Glasses for electrical and electronic components are represented by the lead tubing and cathode-ray-tube screen and cone glasses. These glasses do not operate under severe corrosion conditions, but surfaces must not leach excessive alkali under damp conditions or electrical breakdown can occur. The glass compositions are formulated to give the maximum electrical resistivity and moisture resistance compatible with other necessary properties. 

The resistance of BW tannins (sodium tannates) to thermal breakdown is aided by the presence of sufficient alkali, and optimum stability is conferred at an alkalinity tannin ratio of 2 1. 

Hisatsune and co-workers [290—299] have made extensive kinetic studies of the decomposition of various ions in alkali halide discs. Widths and frequencies of IR absorption bands are an indication of the extent to which a reactant ion forms a solid solution with the matrix halide. Sodium acetate was much less soluble in KBr than in KI but the activation energy for acetate breakdown in the latter matrix was the larger [297]. Shifts in frequency, indicating changes in symmetry, have been reported for oxalate [294] and formate [300] ions dispersed in KBr. 

During the initial stages (when a < 0.04) of the thermal decompositions of the alkali (Na, K, Rb, Cs) perchlorates [845] (giving MC103), the rates of oxygen evolution from all four salts were approximately the same and independent of particle size and sample mass. Experimental values of E ( 190 kJ mole-1) were low compared with those found by Solymosi [846] for the overall reaction (250—290 kJ mole-1) and also lower than the standard enthalpies for anion breakdown (276—289 kJ mole-1) for... 

H2O may be replaced by any acid, HA, and a cyclic mechanism for the breakdown of the ester is quite feasible. For oxidation in alkali the fractional order in hydroxide ion, the low kjkjy and low degree of oxygen-transfer from oxidant are taken as symptomatic of a free-radical chain reaction of the type... 

The weight percentage breakdown of fractions and subfractions obtained from fractionation of both the crude oil and shale oil samples are shown in Figure 3 and 4, respectively. The percentage recoveries of Fraction HI from the crude oU and shale oil samples were 16.5% and 24.1%, respectively. To investigate the interfacial activity of these subfractions upon reaction with alkali, IFT measurements were carried out with a 1% solution of each fraction in toluene against aqueous... 

In a study with 40 healthy men and women, average age 63.7 years, who were randomized to either an alkali diet (meat plus fruits and vegetables) or an acid diet (meat plus cereal grains) (Jajoo and others 2006), altering the renal net acid excretion over a period of 60 days affected several biochemical markers of bone turnover and calcium excretion. The acidity of the diet had a significant effect on increasing NTX, a urinary marker of bone breakdown, and increasing the amount of calcium excreted in the urine. 

The analysis of tetramethylammonium hydroxide (TMAH) solutions manufactured by SACHEM Inc. of Cleburne, Texas, includes the determination of trace elements. These elements cause less-than-optimum performance of integrated circuit boards manufactured by SACHEM s customers that use these solutions in their processes. Alkali and alkaline earth metals (e.g., Li, Na, K, Mg, Ca, and Ba) can reduce the oxide breakdown voltage of the devices. In addition, transition and heavy metal elements (e.g., Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Au, and Pb) can produce higher dark current. Doping elements (e.g., B, Al, Si, P, As, and Sn) can alter the operating characteristics of the devices. In SACHEM s quality control laboratory, ICP coupled to mass spectrometry is used to simultaneously analyze multiple trace elements in one sample in just 1 to 4 min. This ICP-MS instrument is a state-of-the-art instrument that can provide high throughput and low detection Emits at the parts per thousand level. Trace elemental determination at the parts per thousand level must be performed in a clean room so that trace elemental contamination from airborne particles can be minimized. 

The behavior of the fluorosulfinate as an activated alkali fluoride is readily explained in terms of a widening of the fluoride crystal lattice, and the amount of energy required for its breakdown in fluorinations is accordingly lower. 

The penetration into the tissue follows the initial breakdown of the epithelial barrier. This results in an immediate and strong edema of the conjunctiva, known as chemosis, due to a water influx from the surrounding tissue, vascular leakage, tears, and applied fluids. The cornea itself loads up with ions to a measured osmolarity of 1,830 mOsmol/kg after a 1 mol NaOH bum for 30 s [24]. The penetration of strong alkali has been systematically tested on sodium hydroxide by means of evaluation of the anterior chamber pH. This pH change typically occurs within 2 min after exposure of the comeal surface. The change of the cornea... 

If it is also recalled that alkali soluble material (humic acid) builds up much more slowly than acidity (and always markedly dependent on T and [O]), and that the distinctly acidic parent coal is effectively insoluble in alkali, it becomes evident that acidity and alkali solubility are not necessarily covariant, and that accepted definitions of humic acid are, chemically speaking entirely arbitrary. Under the conditions of this study the oxidation appears to involve two simultaneous but seemingly unrelated reactions which result in the development of acidity and in molecular (skeletal) breakdown, respectively, and this suggests that alkali solubility is mainly a consequence of degradation which is only coincidentally connected with the formation of acidic functional groups. Figure 20 illustrates this concept qualitatively and leads to the inference that the wide spread in molecular weights of humic acids reported... 

Sulfasalazine. Salicylazosulfapyridine or Azulfadine [599-79-1] (2-hydroxy-5-[[4[(2-pyridylamino)sulfonyl]-phenyl]azo] benzoic acid) (15) is a light brownish yellow-to-bright yellow fine powder that is practically tasteless and odorless. It melts at ca 255°C with decomposition, is very slightly soluble in ethanol, is practically insoluble in water, diethyl ether, chloroform, and benzene, and is soluble in aqueous solutions of alkali hydroxides. Sulfasalazine may be made by the synthesis described in Reference 13. It is not used as an antidiarrheal as such, but is indicated for the treatment of inflammatory bowel diseases such as ulcerative colitis and Crohn s disease. Its action is purported to result from the breakdown in the colon to 5-aminosalicylic acid [89-57-6] (5-AS A) and sulfapyridine [144-83-2]. It may cause infertility in males, as well as producing idiosyncratic reactions in some patients these reactions have been attributed to the sulfa component of the compound. The mechanism of 5-ASA is attributed to inhibition of the arachidonic acid cascade preventing leukotriene B4 production and the ability to scavenge oxygen free radicals. The active component appears to be 5-aminosalicylic acid. 

Ethanolic alkali, on the other hand, cleaves the pyran ring and may degrade the resulting chain if the temperature is high. For example, 4-methoxyparacotoin (292), a constituent of a South American rosewood essential oil, gives different breakdown products according to the temperature of reaction (57JA4507). 

Alkaline breakdown of monazite. —The flowsheet for the process is given in Fig. 5. For this process it is necessary to remove calcium from the monazite by boiling the mineral with nitric or hydrochloric acid. It has long been known that monazite can be attacked by alkali. Rohden and Peltier [149] have shown the practical applicability of the alkali process for monazite decomposition. The optimum conditions necessary for alkaline decomposition of monazite have been extensively studied by Kaplan and his coworkers [150—153]. 

V which is near the breakdown voltage for this electrolyte and titanium. SIMS data show hydrocarbons, alkali elements, calcium, and most importantly evidence of phosphorus (probably phosphate ion) in the porous film. AES elemental profiles show that phosphorus concentrations are high at the surface and continue on into the film. 

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