Occurrence of Phosphorus

The global occurrence of P differs from that of the other major biogeochemical elements, C, N, S, O, and H in several very important aspects. First, while gaseous forms of P can be produced in the laboratory, none have ever been found in 

Finally, P also differs from other elements in that it is overwhelmingly dominated by a single, stable isotopic form containing 15 protons and 16 neutrons. There are only two naturally occurring radioactive forms of P P and P, which are produced in the atmosphere by nuclear reactions with argon. A small amount of P is 

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Phosphate, PO, is the fully dissociated anion of triprotic phosphoric acid, H3PO4  

Another important class of inorganic PO compounds are the condensed or polyphosphates. In these compounds, two or more phosphate groups bond together via P-O-P bonds to form chains or in some cases cyclic compounds. Although polyphosphates generally account for only a small portion of the total P present in 

The global occurrence of P differs from that of the other major biogeochemical elements, C, N, S, O, and H, in several very important aspects. First, while gaseous forms of P can be produced in the laboratory, none have ever been found in significant quantities in the natural environment. Thus, although some P is transported within the atmosphere on dust particles and dissolved in rain and cloud droplets, the atmosphere generally plays a minor role in the global P cycle. It should be noted, however, that at 

3 days), their activities in the environment are always very low and account for a minute portion of the total P in the Earth. While these isotopes may be useful tracers for processes occurring near the atmospheric source such as the uptake of P in the photic zone of lakes and oceans (Lai and Lee, 1988), they are of little use in deciphering the longer-term aspects of the P cycle. 

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In 1771, C. W. Scheele mentioned the occurrence of phosphorus in bones, while T. Bergman said that the fact was discovered by J. G. Gahn, about 1770. 

A fraction of the sediment bound phosphorus exists in a form which is not extracted with the hydrous metal oxides, but is removed by treatment with dilute hydrochloric acid. This suggests the occurrence of phosphorus in carbonate minerals and/or occurrence of phosphate minerals. 

This chapter discusses the removal of phosphorus by chemical precipitation. It hrst discusses the natural occurrence of phosphorus, followed by a discussion on the modes of removal of the element. The chemical reactions of removal, unit operations of removal, chemical requirements, optimum pH range of operation, and sludge production are all discussed. The chemical precipitation method employed uses alum, lime, and the ferric salts, FeCls and Fe2(S04)3. 

D.R. Peck, The history and occurrence of phosphorus, in Mellor s Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. 8, Supp. 3, Longman, London, 1971. 

The last reaction is the most favored of these three. The actual occurrence of the reactions with elemental phosphorus or phosphorous trichloride as products has been explained to be due to kinetic reasons. The thorium present in the ore volatilizes in the form of thorium tetrachloride (ThCl4) vapor other metallic impurities such as iron, chromium, aluminum, and titanium also form chlorides and vaporize. The product obtained after chlorination at 900 °C is virtually free from thorium chloride and phosphorous compounds, and also from the metals iron, aluminum, chromium, and titanium. 

Nonpharmacologic Therapy Pruritus associated with CKD is difficult to alleviate. It is important to evaluate other potential dermatologic causes of pruritus to maximize the potential for relief. Adequate dialysis is generally the first line of treatment in patients with pruritus. However, this has not been shown to decrease the incidence of pruritus significantly. Maintaining proper nutritional intake, especially with regard to dietary phosphorus and protein intake, may lessen the degree or occurrence of pruritus. Patients who do not attain relief from other measures may benefit from ultraviolet B phototherapy. 

Noteworthy NMR studies involving nuclei other than phosphorus have been carried out for some P-chloro-NHPs where the possible occurrence of spontaneous P-Cl bond dissociation was probed by II NMR titrations and 35C1 NMR [20], and for P-cyclopentadienyl derivatives where measurement of solid-state 13C CP-MAS NMR spectra allowed one to substantiate the preservation of the circumambulatory ring migration of cyclopentadienyl groups in the solid state [47], Several neutral and cationic derivatives have also been studied by 15N NMR [20, 53],... 

For example, in the instance of 9-chloroacridine, the attachment of the halogen (leaving group) at a suitably electrophilic carbon site allows the occurrence of a replacement reaction, presumably occurring via an addition-elimination procedure for phosphorus attachment, followed by the common nucleophilic displacement (ester cleavage) of the Michaelis-Arbuzov process (Figure 6.1).4... 

The controlled occurrence of two electrophilic aromatic substitution reactions at a single phosphorus center using phosphorus trichloride has been accomplished using aluminum chloride as the catalyst, but with tris(2-chloroethyl) phosphite as the agent for the decomposition of the adduct-Lewis acid complex (Figure 6.13).60... 

Occurrence. Widely distributed in many minerals (more than 200 minerals are known). Commercial sources of phosphorus are apatites (for instance fluoroapatite [3Ca3(P04)2 Ca(F,Cl)2]). 

This circular reviews the occurrence of 34 trace elements in coal and the occurrence and distribution of chlorine, phosphorus, titanium, and manganese, which are not considered rare in coal. Separate chapters are devoted to germanium, gallium, and uranium in coal. 

For many years the occurrence of double and triple bonds such as discussed above for silicon and phosphorus was equally rare among other nonmetals, leading to the conclusion that only C=C, C =N, C 0. NsN. etc. were stable multiple bonds. This, of course, was taken as challenge and much svnthetic work was directed at the problem. None of the multiple bonds between heavier nonmetals is as strong as those between the 2p elements. Some typical estimates of the strength of the n bond (cf. to H,C CH3 as a "standard" from organic chemistry) arc (values in kJ mol-1). ... 

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