For removing impurities

Desorex A process for removing impurities from industrial gases by adsorption on activated carbon. Offered by Lurgi. 

J. Shi and J. Yordan, Process for Removing Impurities from Kaolin Clays, US Pat. 5522986,1996. 

Other methods for removing impurities from crude polyphenylenesulfide are discussed by Miyahara et al. (2). 

Figure 5. Scheme for removing impurities from protein substrate by hydrolysis, purification, and resynthesis via the plastein reaction (i)... 

It is necessary to purify the reagents used for determinations of the more common heavy metals. Also, there should be very little if any metallic contamination of many of the materials required for biochemical studies. The main methods for removing impurities of this type are as follows. 

One of the most common low-temperature methods for removing impurities involves the use of selective solid adsorbents. Such materials as silica gel, carbon, and synthetic zeolites (molecular sieves) are widely used as adsorbents because of their extremely large effective surface areas. Most of the gels and carbons have pores of various sizes in a given sample, but the synthetic zeolites can be manufactured with closely controlled pore size openings ranging from 0.4 to 1.3 nm. This additional selectivity is useful because it permits separation of gases on the basis of molecular size. 

As a simulation example we treat the production of biodiesel from rapeseed in a plant capacity of 200 ktonne per year. The feedstock has a high content of oleic acid triglyceride, around 65%, such that the kinetic data from Section 14.6 can be used for sketching the design of the reaction section. For simplification, we consider that the oil was pretreated for removing impurities and gums, as well as FFA by esterification over solid catalyst. The free fatty acids and water content in oil feed should be less than 0.5%w. NaOH and KOH in 0.5 to 1.5% w/w are used as catalysts. 

Depending on the required level of purity, the step used for removing impurities can be a single or multiple-step chromatography operation. Table 32.8 summarizes chromatographic methods that can be used to remove impurities following the capture step.76-78 80... 

C02 Wash A process for removing impurities from landfill gas, leaving only methane and carbon dioxide. The gas is washed with liquid carbon dioxide, isolated from the landfill gas. Developed by Acrion Technology and first demonstrated in Goshen, NY, in 1998. 

F. M. Dautzenberg, H.W. Kouwenhoven, J.E. Naber, and C.W.J. Verweij (Shell Internationale Research Mij. N.V), Apparatus and molded articles as catalysts and acceptors for removing impurities, especially sulfur dioxide, from stack gases, Ger. Offenl. 2,037,194 (1971). 

Uneven wash application will result in decreased efficiency for removing impurities from batch. 

Betts process. An electrolytic process for removing impurities from lead in which pure lead is deposited on a thin cathode of pure lead from an anode containing as much as 10% of silver, gold, bismuth, copper, antimony, arsenic, selenium, and other impurities. The electrolyte is lead fluosilicate and fluosilicic acid. The scrap anodes and the residues of impurities associated with them are either recast into anodes or treated to recover antimony lead, silver, gold, bismuth, etc. 

Activated carbon will remove much of the pink color from commercial solutions of potassium hydroxide, sodium hydroxide, and sodium carbonate. Carbon is also useful for removing impurities that cause foaming. At times, difficulty is experienced in completely separating the carbon from caustic solutions because of a peptizing action. 

Carbon nanomaterials often contain impurities which can dramatically influence or even dominate their properties. Physical methods have been developed for removing impurities however this approach is complicated, time-consuming and less effective than other techniques [40], The most common method of purification is by oxidation, which is highly effective but changes the structure of the nanomaterials [20,40-42],... 

If liquid oxygen is to be handled, stored, or transferred under conditions where large losses are involved, then it is apparent that means for removing impurities which tend to concentrate may be required. A circulating system whereby the liquid oxygen is passed through silica gel will serve the purpose. 

True or false The HNOjfaq) for removing impurities can be reused. 

---