Puffing

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled. 

H. Aranha-Creado, K. Oshima, S. Jafari, G. Howard, Jr., and H. Brandweia, Scientific and TechnicalEeport STR-PUF-24, Pall Ultrafine Filtration Co., East HiUs,N.Y., 1995. 

The plutonium extracted by the Purex process usually has been in the form of a concentrated nitrate solution or symp, which must be converted to anhydrous PuF [13842-83-6] or PuF, which are charge materials for metal production. The nitrate solution is sufficientiy pure for the processing to be conducted in gloveboxes without P- or y-shielding (130). The Pu is first precipitated as plutonium(IV) peroxide [12412-68-9], plutonium(Ill) oxalate [56609-10-0], plutonium(IV) oxalate [13278-81-4], or plutonium(Ill) fluoride. These precipitates are converted to anhydrous PuF or PuF. The precipitation process used depends on numerous factors, eg, derived purity of product, safety considerations, ease of recovering wastes, and required process equipment. The peroxide precipitation yields the purest product and generally is the preferred route (131). The peroxide precipitate is converted to PuF by HF—O2 gas or to PuF by HF—H2 gas (31,132). 

Preparation of Plutonium Metal from Fluorides. Plutonium fluoride, PuF or PuF, is reduced to the metal with calcium (31). Although the reactions of Ca with both fluorides are exothermic, iodine is added to provide additional heat. The thermodynamics of the process have been described (133). The purity of production-grade Pu metal by this method is ca 99.87 wt % (134). Metal of greater than 99.99 wt % purity can be produced by electrorefining, which is appHcable for Pu alloys as well as to purify Pu metal. The electrorefining has been conducted at 740°C in a NaCl—KCl electrolyte containing PuCl [13569-62-5], PuF, or PuF. Processing was done routinely on a 4-kg Pu batch basis (135). 

Only Pu(III) oxyhahdes (PuOF, PuOCl, PuOBr, and PuOI) and Pu(VI) oxyhaHdes (PUO2F2, PuOF, and PUO2CI2 6H20) are known. Of these the most important are PuOCl, which is the stable product of hydrolysis of PUCI3 (s) with H2O (g) (157), and PUO2F2, which is the product of low temperature hydrolysis of PuF and one of the products of room temperature hydrolysis of PuF (158—160). 

Rapid heating of either borax decahydrate or pentahydrate causes the crystal to dissolve before significant dehydration, and at about 140°C, puffing occurs from rapid vaporisation of water to form particles having as high as 90% void volume and very low bulk density (78). 

High carbon yielding resins are sometimes employed as raw material precursors for specialty carbons. Various chemical additives are also used in low concentrations to improve the processabiHty or to control puffing during graphitization. 

Filter aids should have low bulk density to minimize settling and aid good distribution on a filter-medium surface that may not be horizontal. They should also be porous and capable of forming a porous cake to minimize flow resistance, and they must be chemically inert to the filtrate. These characteristics are all found in the two most popular commercial filter aids diatomaceous silica (also called diatomite, or diatomaceous earth), which is an almost pure silica prepared from deposits of diatom skeletons and expanded perhte, particles of puffed lava that are principally aluminum alkali siheate. Cellulosic fibers (ground wood pulp) are sometimes used when siliceous materials cannot be used but are much more compressible. The use of other less effective aids (e.g., carbon and gypsum) may be justified in special cases. Sometimes a combination or carbon and diatomaceous silica permits adsorption in addition to filter-aid performance. Various other materials, such as salt, fine sand, starch, and precipitated calcium carbonate, are employed in specific industries where they represent either waste material or inexpensive alternatives to conventional filter aids. 

PF/PUF phenol-formaldehyde and phenol-urea-formaldehyde-resin. 

Using such PUF-resins, the resin content of the board should be calculated only based on the PF-resin solids in the PUF-resin. 

Fig. 1. Schematic representation of the coreaction of urea and phenol with formaldehyde to give PUF resins when reacted under alkaline reaction conditions.

Hedley, ef al., "Puffing Billy" with 4 and control of steam locomotive... 

Plutonium(lV), Pu+Yagj, forms a complex ion with fluoride ion, PUF+3 ... 

Pineneozonide and Pineneoxoozonide. A compn corresponding to something between Cj oHj 03 and Cj 0Hj 604 was obtained by Harries Nere-sheuner (Ref 2) on treating right-rotary turpentine with weak ozone. It could be sepd into thick oily (80—90% of the total) and solid fractions. The mixt was insol in common org solvents, and puffed off when heated on a spatula... 

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