Purification and Refinement

The purification and refinement operations can be batch or continuous. The raw blue is crushed and ground, slurried in warm water, then filtered and washed to remove the sulfoxides. Reslurrying and wet grinding release the sulfurous impurities and reduce the ultramarine particle size, often to 0.1-10.0 pm. The impurities are floated off by boiling or cold froth flotation, analogous to techniques used in the mining industry. 

Violet ultramarine can be prepared by heating a mid-range blue grade with ammonium chloride at ca. 240 °C in the presence of air. Treating the violet with hydrogen chloride gas at 140 °C gives the pink derivative. 

A good ultramarine pigment would meet the following specification  

Tinting strength/standard Reduced shade/standard Free sulfur Water-soluble matter Sieve residue (45 rm) Moisture Heavy metals 

The stability and safety of ultramarine pigments are the basis of their wide range of applications, which include the following  

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On the industrial scene, the most prominent applications both in scale and number are seen in the petroleum industry. Liquid extraction is used here to separate petroleum fractions selectively and to purify or otherwise refine them. In the Edeleanu process, which is close to a century old, liquid sulfur dioxide is used to extract aromatics from various feedstocks. The removal of the ever-present sulfur compounds is accomplished by extraction with sodium hydroxide solutions. In addition, a wide range of organic solvents is used in the purification and refining of various lubricants. 

The oil derives from - linseed. Various purification and refining techniques are used. Heat-treated 1. (260-280 °C) increases viscosity and gives boiled 1. Blowing air into the oil yields blown 1. (- drying oils). ->Hydrolysis is used to make the fatty acids. 

Recovery and Purification. AH processes for the recovery and refining of maleic anhydride must deal with the efficient separation of maleic anhydride from the large amount of water produced in the reaction process. Recovery systems can be separated into two general categories aqueous- and nonaqueous-based absorption systems. Solvent-based systems have a higher recovery of maleic anhydride and are more energy efficient than water-based systems. 

Wastes from petroleum refining, natural gas purification and pyrolitic treatment of coal Wastes from inorganic chemical processes Wastes from organic chemical processes... 

There are several processes for extracting and refining niobium from its ores. (Payton, P.H. 1981. Niobium and Niobium Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3 . ed., Vol, 15, pp. 820-827. New York Wiley Interscience). The process of choice depends on nature of the ore and end use intended for the metal. Some common steps in these recovery processes involve ore preconcentration, breaking or opening the ore, obtaining pure niobium compounds, reduction of niobium compounds to niobium metal, purification or refining metal and fabrication. If niobium is extracted from a niobium-tantalum ore, the most important step is separation of niobium from tantalum, both of which are chemically very similar. 

For the purposes of making polyols from these triglycerides, oils which contain a high level of unsaturation are desirable. Oils such as soy, canola, and sunflower are acceptable due to relatively low levels of saturated fatty acids, while feedstocks such as palm oil are considered unusable without further purification or refinement due to high levels of saturated fatty acids. Table 1 outlines the composition of several oils (3). 

R.A. Findlay and J.A. Weedman, Separation and purification by crystallization, in Advances in Petroleum Chemistry and Refining, Wiley-Interscience, New York, 1958, Vol. 1, pp. 118-209. 

Crystals and X-ray Data Collection. Detailed information concerning protein purification, crystallization, and X-ray data collection can be found in a previous report (Xu et al., 1991) and will be mentioned here in summary form. Recombinant murine apo-ALBP crystallizes in the orthorhombic space group P2j2i2i with the following unit cell dimensions a = 34.4 A, b = 54.8 A, and c = 76.3 A. The asymmetric unit contains one molecule with a molecular weight of 14,500. The entire diffraction data set was collected on one crystal. In the resolution range t -2.5 A, 5115 of the 5227 theoretically possible reflections were measured. Unless otherwise noted the diffraction data with intensities greater than 2a were used for structure determination and refinement. As can be seen in Table 8.2, this included about 96% of the measured data. 

The actual purification is somewhat less than that predicted by Equation (10.15) and by Figure 10.11 because mixing is not perfect in the liquid. A thin boundary layer of impurity forms in the liquid just ahead of the interface. See Figure 10.12. The formation of a boundary layer causes the concentration of the impurity in the liquid at the liquid-solid interface to be greater than for perfect mixing. Therefore, there is less purification. Zone refining is most efficient in relatively pure materials, where the boundary layer builds up. 

Humans have been exposed more and more to metallic contaminants in the environment, mostly from the products of industry. There are three main sources of metals in the environment. The most obvious are the processes of extraction and purification mining, smelting, and refining. Another is the release of metals from fossil fuels (e.g., coal, oil), when these are burned. Cadmium, lead, mercury, nickel, vanadium, chromium, and copper are all present in these fuels, and considerable amounts enter the air or are deposited in ash. The third and most diverse source is the production and use of industrial products containing metals, which is increasing as new applications are found. The modem chemical industry, for example, uses many metals or metal compounds as catalysts metal compounds are used as stabilizers in the production of many plastics, and metals are added to lubricants, which then find their way into the environment.21... 

The A-starch slurry from the centrifugal decanter is screened and then refined either with hydrocyclones or with separators and decanters. Purification and concentration of A-starch is accomplished in multistage hydrocyclones, or the A-starch slurry is separated into A and B fractions in a nozzle-type centrifuge and the A-starch fraction is finally refined in a centrifugal decanter. The B-starch stream is passed through vibrating screens and concentrated in a decanter. Pentosans and other solubles are concentrated and either dried or co-fermented with the B-starch for ethanol production. 

The progress of the purification will be monitored by analytical HPLC. See the analytical HPLC gradient for details. This method will have been developed in the Development Group and refined in the QC department... 

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