Precipitated characterization

Allowing TiCl3(THF)3 and [VO(acen)] to react in THF at room temperature, a reducti deoxygenation of the V02+ occurs and a red solid precipitates, characterized as [Vn... 

MAN/GAL] Manceau, A., Gallup, D. L., Removal of selenocyanate in water by precipitation characterization of copper-selenium precipitate by X-ray diffraction, infrared, and X-ray absorption spectroscopy, Environ. Sci. Technol., 31, (1997), 968-976. Cited on page 297. 

Section 2.3.2 also shows data for the FRRPP formation of PMAA with water as solvent/precipitant. Characterization of the results were painstakingly done by Aggarwal (1993) and resulted in the validity of producing samples of this material as secondary and even primary standards. As shown in Fig. 2.3.20, relatively high molecular weights were obtained, reaching beyond 100,000 Da. 

Swash, P. M. Monhemius, A. J. 1995. Hydro-thermal precipitation, characterization and solubility testing in the Fe-Ca-As04 system. In Sudbury 95. 

Common teniiinology used to characterize impurities and defects in semiconductors includes point and line defects, complexes, precipitates and extended defects. These teniis are somewhat loosely defined, and examples follow. 

The following experiments may he used to illustrate the application of titrimetry to quantitative, qtmlitative, or characterization problems. Experiments are grouped into four categories based on the type of reaction (acid-base, complexation, redox, and precipitation). A brief description is included with each experiment providing details such as the type of sample analyzed, the method for locating end points, or the analysis of data. Additional experiments emphasizing potentiometric electrodes are found in Chapter 11. 

Monofluorophosphates. Monofluorophosphates are probably the best characterized series of fluoroxy salts. The PO F ion is stable ia neutral or slightly alkaline solution. The alkaU metal and ammonium monofluorophosphates are soluble ia water but the alkaline-earth salts are only slightly soluble, eg, CaPO F is not water-soluble and precipitates as the dihydrate. 

Nickel—Copper. In the soHd state, nickel and copper form a continuous soHd solution. The nickel-rich, nickel—copper alloys are characterized by a good compromise of strength and ductihty and are resistant to corrosion and stress corrosion ia many environments, ia particular water and seawater, nonoxidizing acids, neutral and alkaline salts, and alkaUes. These alloys are weldable and are characterized by elevated and high temperature mechanical properties for certain appHcations. The copper content ia these alloys also easure improved thermal coaductivity for heat exchange. MONEL alloy 400 is a typical nickel-rich, nickel—copper alloy ia which the nickel content is ca 66 wt %. MONEL alloy K-500 is essentially alloy 400 with small additions of aluminum and titanium. Aging of alloy K-500 results in very fine y -precipitates and increased strength (see also Copper alloys). 

Over 50 acidic, basic, and neutral aluminum sulfate hydrates have been reported. Only a few of these are well characterized because the exact compositions depend on conditions of precipitation from solution. Variables such as supersaturation, nucleation and crystal growth rates, occlusion, nonequilihrium conditions, and hydrolysis can each play a role ia the final composition. Commercial dry alum is likely not a single crystalline hydrate, but rather it contains significant amounts of amorphous material. 

Sorption and Desorption Processes. Sorption is a generalized term that refers to surface-induced removal of the pesticide from solution it is the attraction and accumulation of pesticide at the sod—water or sod—air interface, resulting in molecular layers on the surface of sod particles. Experimentally, sorption is characterized by the loss of pesticide from the sod solution, making it almost impossible to distinguish between sorption in which molecular layers form on sod particle surfaces, precipitation in which either a separate soHd phase forms on soHd surfaces, covalent bonding with the sod particle surface, or absorption into sod particles or organisms. Sorption is generally considered a reversible equdibrium process. 

Incompletely Characterized Carbon Sulfides. A poorly characterized black soHd, known as carsul, occurs as a residue ia sulfur distillation or as a precipitate ia molten Frasch sulfur (12,13). Although this material may approach the composition of a carbon sulfide, it is more likely also to contain some chemically bound hydrogen and possibly other elements. Carbon—sulfur surface compounds of the formula C S, where xis greater than 4,... 

The chlorinity. Cl (%e), is determined by the titration of seawater with AgNO. It was defined as the chlorine equivalent of the total hahde concentration ia g kg seawater it is now defined as the mass ia grams of Ag necessary to precipitate the halogens (Cl and Br ) ia 328.5233 g of seawater. It has been adequately demonstrated that the relative composition of the major (greater than 1 m kg seawater) components of seawater is nearly constant. By measuriag one constituent of seawater, the composition of other components can be characterized. The constituent normally selected is the chlorinity. Cl... 

Analysis. Butenes are best characterized by their property of decolorizing both a solution of bromine in carbon tetrachloride and a cold, dilute, neutral permanganate solution (the Baeyer test). A solution of bromine in carbon tetrachloride is red the dihaUde, like the butenes, are colorless. Decoloration of the bromine solution is rapid. In the Baeyer test, a purple color is replaced by brown manganese oxide (a precipitate) and a colorless diol. These tests apply to all alkenes. 

Cement plants in the United States are now carehiUy monitored for compliance with Environmental Protection Agency (EPA) standards for emissions of particulates, SO, NO, and hydrocarbons. AH plants incorporate particulate collection devices such as baghouses and electrostatic precipitators (see Air POLLUTION CONTROL methods). The particulates removed from stack emissions are called cement kiln dust (CKD). It has been shown that CKD is characterized by low concentrations of metals which leach from the CKD at levels far below regulatory limits (63,64). Environmental issues continue to be of concern as the use of waste fuel in cement kilns becomes more widespread. 

With the microfocus instrument it is possible to combine the weak Raman scattering of liquid water with a water-immersion lens on the microscope and to determine spectra on precipitates in equilibrium with the mother liquor. Unique among characterization tools, Raman spectroscopy will give structural information on solids that are otherwise unstable when removed from their solutions. 

Fouling can be characterized by mechanism and location. Membranes can foul in three places on, above or within the membranes (refer to the sidebar on the next page). The term agglomeration in the general sense, describes colloidal precipitates... 

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