Solublizing, phosphate

In the double-neutralization process, Na2SiFg is precipitated and removed by filtration at a pH of 3—4 (9). Upon raising the pH to 7—9, insoluble phosphates of Fe, Al, Ca, and Mg form and separate. Iron can be precipitated as hydrous ferric oxide, reducing the phosphate loss at the second filter cake. Both the fluorosihcate and metal phosphate filter residues tend to be voluminous cakes that shrink when dewatered recovery of soluble phosphates trapped within the cakes is difficult. 

Sodium alumiaate is an effective precipitant for soluble phosphate ia sewage and is especially useful ia wastewater having low alkaliaity (20,21). Sodium alumiaate hydrolyzes ia water to Al(OH)2 and Al" which precipitate soluble phosphate as aluminum phosphate [7784-30-7], AlPO. Sodium alumiaate has also been described as an effective aid for the removal of fluorides from some iadustrial waste waters (22). Combiaations of sodium alumiaate and other chemicals are being used to improve the detackification of paint particles ia water from spray-painting operations (23). 

Silver Phosphates. Silver phosphate [7784-09-0], or silver orthophosphate, Ag3P04, is a bright yellow material formed by treating silver nitrate with a soluble phosphate salt or phosphoric acid. Silver pyrophosphate [13465-97-9], is a white salt prepared by the addition of a soluble... 

Titanium Phosphates. Titanium(III) phosphate [24704-65-2] (titanous phosphate) is a purple soHd, soluble ia dilute acid, giving relatively stable solutions. It can be prepared by adding a soluble phosphate to titanous chloride or sulfate solution and raising the pH until precipitation occurs. 

Phosphoms determination involves the conversion of phosphoms to soluble phosphate by digesting the coal ash with a mixture of sulfuric, nitric, and hydrofluoric acids (18). Phosphate is precipitated as ammonium phosphomolybdate, which may be reduced to give a blue solution that is determined colorimetricaHy or volumetricaHy (D2795) (18). 

Improved nucleation within the phosphate solution itself can produce smoother coatings without the necessity of recourse to preliminary chemical treatment. This may be accomplished by introducing into the phosphating bath the sparingly soluble phosphates of the alkaline earth metals or condensed phosphates such as sodium hexametaphosphate or sodium tripolyphosphate. Such modified phosphating baths produce smoother coatings than orthodox baths and are very much less sensitive to cleaning procedures. 

Congruent phosphate programs are modifications of coordinated phosphate programs that operate at a Na P04 ratio lower than the normal 2.8 or 2.85 1. Experience has demonstrated that (contrary to theory) diminished phosphate salt solubility (phosphate hideout) takes place under high-load conditions. This is in addition to the recognized problems of high-temperature crystallization of TSP at the higher ratio of 3 1 (with the formation of some DSP and free caustic). 

Carbonate and phosphate control is vital. If a minimum carbonate alkalinity of 250 mg/1 expressed in terms of CaC03 is consistently maintained when carbonate control or sodium ion exchange softening is used, a residual of soluble phosphate need not be maintained. A residual of soluble hardness up to 5 mg/1 expressed in terms of CaC03 is then usually found in the BW, but scale formation may be minimized by phosphate or carbonate conditioning treatment. 

PHOSPHATATION A clarification process where phosphoric acid or a soluble phosphate is used with lime and heat. The impurities are removed by flocculation, flotation, and surface scraping. 

Wilson, Kent Lewis (1970) in a long-term study found that most of the soluble phosphate was eluted from the cement in the first 24 hours. By contrast the rate of elution of zinc remained constant for 160 days, the length of the study. They concluded that long-term erosion took place at the surface of the oxide particles rather than in the matrix. 

It is not clear whether the conditions used in the above experiments correspond to those present on the young Earth. Cyanate has been detected in cosmic nebulae (Yamagata, 1999), while water-soluble phosphates and diphosphates can be formed during volcanic activity, as Yamagata showed as early as 1991 (see Sect. 4.7.3). 

Fosphenytoin, the water-soluble phosphate ester of phenytoin, is a phenytoin prodrug. 

A different application of visible microscopy was pioneered by Gomori. In 1941 he showed that alkaline phosphatase could be specifically located by its hydrolysis of soluble phosphate esters (initially glycerophosphate). If calcium ions were present in the medium in which the sections were incubated, insoluble calcium phosphate precipitated as a result of the action of the hydrolase. The site of the precipitate could be visualized if cobalt or lead salts were subsequently added to replace calcium and the sections exposed to hydrogen sulfide. In principle many hydrolases and other enzymes could be studied using the appropriate substrates and precipitants. It was important to ensure that the products of the enzyme reactions did not diffuse from the sites where the enzymes were located. It was also essential that the reagents could reach the enzyme site. 

The example of amprenavir, an HIV-1 protease inhibitor, shows that intestinal metabolism can also be used as a strategy to enhance the bioavailability of compounds. In the biopharmaceutics classification system (BCS), amprenavir can be categorized as a class II compound it is poorly soluble but highly permeable [51]. Fosamprenavir, the water-soluble phosphate salt of amprenavir, on the other hand, shows poor transepithelial transport. However, after oral administration of fosamprenavir, this compound is metabolized into amprenavir in the intestinal lumen and in the enterocytes mainly by alkaline phosphatases, resulting in an increased intestinal absorption [51, 174],... 

J. Leppanen, J. Huuskonen, J. Savolainen, T. Nevalainen, H. Taipale, J. Vepsalainen, J. Gynther, T. Jarvinen, Synthesis of a Water-Soluble Prodrug of Entacapone , Bioorg. Med. Chem. Lett. 2000, 10, 1967-1969 R. Sauer, J. Maurinsh, U. Reith, F. Ftille, K. N. Klotz, C. E. Muller, Water-Soluble Phosphate Prodrugs of l-Propargyl-8-styryl-xanthine Derivatives, A2A-Selective Adenosine Receptor Antagonists , J. Med. Chem. 2000, 43, 440-448. 

Y. Ueda, J. D. Matiskella, A. B. Mikkilineni, V. Farina, J. O. Knipe, W. C. Rose, A. M. Casazza, D. M. Vyas, Novel, Water-Soluble Phosphate Derivatives of 2 -Ethoxycarbo-nylpaclitaxel as Potential Prodrugs of Paclitaxel Synthesis and Antitumor Evaluation , Bioorg. Med. Chem. Lett. 1995, 5, 247 - 252. 

Forrester Environmental Services, Inc., has developed a group of technologies for the stabilization of wastes containing heavy metals, such as lead, cadmium, arsenic, mercury, copper, zinc, and antimony. These technologies have been used in both industrial pollution prevention and remediation applications. One version of the technology involves the use of water-soluble phosphates and various complexing agents to produce a less soluble lead waste. This process results in a leach-resistant lead product. 

The WES-PHix process is designed to chemically stabilize ash from municipal solid waste combustion. This technology reduces the solubility of certain heavy metals in ash through the addition of soluble phosphate, lime, and water. The addition of these reagents to ash promotes... 

Figure 2.1 The cell membrane consists mainly of lipids (fats), proteins, and carbohydrates in the form of a lipid bilayer. The two lipid layers face each other inside the membrane, and the water-soluble phosphate groups of the membrane face the watery contents inside the cell (the cytoplasm) and outside the cell (the interstitial fluid).

Crannell, B. S., Eighmy, T. T., Krzanowski, J. E., Eusden, J. D. Jr., Shaw, E. L. Francis, C. A. 2000. Heavy metal stabilization in municipal solid waste combustion bottom ash using soluble phosphate. Waste Management, 20, 135-148. 

Uchida, T., Itoh, I. Harada, K. 1996. Immobilization of heavy metals contained in incinerator fly ash by application of soluble phosphate - treatment and disposal cost reduction by combined use of high specific surface area lime . Waste Management, 16, 475-481. 

Absorption of phenytoin is highly dependent on the formulation of the dosage form. Particle size and pharmaceutical additives affect both the rate and the extent of absorption. Absorption of phenytoin sodium from the gastrointestinal tract is nearly complete in most patients, although the time to peak may range from 3 to 12 hours. Absorption after intramuscular injection is unpredictable, and some drug precipitation in the muscle occurs this route of administration is not recommended for phenytoin. In contrast, fosphenytoin, a more soluble phosphate prodrug of phenytoin, is well absorbed after intramuscular administration. 

Divalent cations. Addition of calcium to milk causes precipitation of soluble phosphate as colloidal calcium phosphate, an increase in ionized calcium, a decrease in the concentration of soluble phosphate and a decrease in pH. 

Citrate. Addition of citrate reduces the concentrations of calcium ions and colloidal calcium phosphate and increases the soluble calcium, soluble phosphate and pH. 

Precipitation of soluble calcium phosphate as Ca3(P04)2 with the release of H+. After heating at 140°C for 5-10 min, most (> 90%) of the soluble phosphate has been precipitated. 

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