Nitrogen contaminants

The breakdown of organic contaminants present in the MU water to produce ammonia (from nitrogenous contaminants), phenols and carboxylic acids (from humic and fulvic acids), and tri-halomethanes (from the by-products of chlorination)... 

The original route from p-xylene was oxidation in the presence of nitric acid. But the use of nitric acid is always problematical. There are corrosion and potential explosion problems, problems of nitrogen contamination of the product, and problems due to the requirement to run the reactions at high temperatures. Just a lot of problems that all led to the development of the liquid air phase oxidation of p-xylene. Ironically the nitrogen contamination problem was the reason that the intermediate DMT route to polyester was developed, since that was easy to purify by distillation. Subsequently, DMT has secured a firm place in the processing scheme. 

Economics The solvent used in the Sulfolane process exhibits higher selectivity and capacity for aromatics than any other commercial solvent. Using the Sulfalane process minimizes concern about trace nitrogen contamination that occurs with nitrogen-based solvents. Estimated inside battery limits (ISBL) costs based on a unit processing 158,000 mtpy of BT reformate feedstock with 68 LV% aromatics (US Gulf Coast site in 2003). 

It is well known that nitrogen can be easily incorporated in diamond, and usually, it must be very eareful of the air leak in the CVD chamber to prevent nitrogen contamination of diamond films. It is also known that addition of too much nitrogen to the source gas resulted in microcrystalline diamond films rather than well-faceted films. However, Koidl s group found [90] using a NIRIM-type reactor that an addition of small amount of N2 gas to the source gas of c=l-2%CH4/H2 resulted in pronounced (100)-textured films, while the film became microcrystalline without N2 addition. More specifically, an addition of 40-200 ppm of N2 to the... 

Besides the nitrogen contamination due to pollution of the carrier gas, the diamond films obtained by chemical vapour deposition (CVD) are usually contaminated with silicon. This contamination originates from the plasma etching of the silica walls of the reactor and of the commonly used silicon substrates [37]. 

Jingsheng C, Xuemin G, Dawei H, et al. 2000. Nitrogen contamination in the Yangtze river system, China. J Hazard Mater 73(2) 107-113. 

A very effective way of decreasing nitrogen contamination is the replacement of the graphite crucible by a tantalum one. A substantial decrease in nitrogen concentration was observed in [10] for the tantalum crucible. The dependences of nitrogen concentration on its concentration in the source material for the graphite and tantalum crucibles observed in [10] are shown in FIGURE 12. A lower compensation level is also observed for the case of tantalum components. 

Hoshi et al. studied their films by TEM as well. From the corresponding electron diffraction patterns they inferred that phase separation had taken place, involving the formation of a nitride or oxide of part of the Gd. Both the oxygen-contaminated film and the nitrogen-contaminated film had essentially the same microstructure and this microstructure was not composed of columns usually obtained by means of sputtering. From these results the authors conclude that shape anisotropy associated with structural or compositional fluctuations apparently contributes little to the perpendicular anisotropy in Gd-Co films. 

A specialized application that can result in nitrogen contamination of salt is the use of amines as separators in the recovery of KCl from mixed ores such as sylvinite (Section 7.1.6.2A). 

Atkins [164] developed a precision instrument for use in the carbon black industry. For precision measurements he stated that it was necessary to consider changes in ambient temperature, barometric pressure, liquid nitrogen temperature and nitrogen contamination in the gas mixture. Correction for non-linearity of the catherometer is also necessary. Atkins used heat exchanger coils in the detector circuit in addition to temperature control of the detector. 

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