Carbonate contamination, amount

Also, the hot-lime-softened water has variable amounts of carbonate contamination. When boiler feedwater is converted to steam, the carbonate deposits will break down into carbon dioxide and hardness deposits. 

CHARACTERIZATION OF LEAD IODIDE CRYSTALS. The AES data of Figure 4 suggest that very pure crystals of lead Iodide were grown in the shuttle. The amount of carbon contaminant is appreciably lower than the earth grown crystals (Figure 5) and the ratio of iodide to lead is much closer to the ideal ratio of 2 for the shuttle grown crystals than the earth grown materials. 

Alkaline fuel cells (AFCs) have been around the longest amount of time. They utilize potassium hydroxide and are susceptible to carbon contamination. 

Hectorite was investigated by DTA by Earnest (189) using furnace atmospheres of dynamic nitrogen, air, carbon dioxide, and static air. Hectorite specimens found in California are always associated with large amounts of calcite and, in some cases, varying amounts of dolomite. Thus, most published T A curves reflect not only the thermal behavior of hectorite but also that of the carbonate contaminant. A typical DTA curve of hectorite is shown in Figure 7.10. An endothermic peak at A7, in of 121°C is caused by the interlayer... 

Taken together, these results support the hypothesis that EUV photoinduced hydrocarbon cracking, mediated by photoelectrons, is responsible for carbon contamination in EUV optics. This is referred to as the hydrocarbon cracking model. These results are supported by the model on a number of grounds. First, for a fixed amount of hydrocarbons in the vicinity of the mirror surface, the carbon growth increases with the number of photons and/or photoelectrons... 

Djega-Mariadassou and co-workers (67) reported that a long induction period preceded the simultaneous reduction and carburization steps in the synthesis of NbC from the TPRe of niobium oxide with CH4/4H2. To avoid the long induction period, different catalysts were incorporated into the initial Nb205 and were treated with CH4/4H2 mixtures at relatively low carburization temperatures. In the presence of catalysts of methane decomposition (Ni and Rh), they were able to eliminate the induction period and fee 5-NbC with superficial carbon contamination and surface areas of 11-18 m /g were obtained. When a NiMo catalyst was mixed with Nb205 and carburized with a CH4/4H2 mixture gas, 5-NbC with a surface area of 50 m /g and large amounts of carbon contamination was produced. They also synthesized 5-NbC with surface areas of 27-49 m /g from the carbonization of niobium oxynitrides, which were prepared from the nitridation of niobium oxide with pure ammonia at 923 K. 

VASE measurements reveal a thickness of 1.3—1.4 nm for densely packed monolayers of PFAND. The difference between molecular length (Rs 2.1 nm) and measured adlayer thickness is attributed to three considerations (i) relaxed PFAND molecules are most likely not straight but helical and bent as in the case of fluorinated alkyl thiols, (ii) adsorbed PFAND molecules, as fluorinated alkyls, might be tilted with respect to the surface normal by 30°-35° to optimize packing and intermolecular interactions, and (iii) VASE-determined thickness is systematically underestimated by the layer model that was employed, because of adventitious carbon/contamination, which is constantly replaced by PFAND during adsorption, a process referred to as self-cleaning by Buck et al. for thiols on gold. Comparison of C Is XP spectra allows an estimation of the replacement of surface contamination the amount of contamination on clean TiO surfaces is equivalent to a fraction (20-25%) of what is... 

The presence of adventitious carbon contamination can have a drastic influence on the quantitative evaluation of XP spectra. The amount of the contamination will vary with the different treatments, and both removal and buildup can occur, the latter usually being faster on the freshly treated (active) surface than on the untreated one. 

To eliminate the problem of the varying amount of carbon contamination, use an XPS quantification method that employs variable correction factors... 

Carbon contamination of the produced sulfur can result from liquid hydrocarbon droplets in the feed gas or by condensation of feed gas hydrocarbons. This problem is besr avoided by operating the process about 10°F above the feed gas hydrocarbon dew point and by removing any hydrocarbon aerosol in the feed gas (compressor lube oil, etc.) with a coalescing filter (Allen, 1995). Yet another potential form of sulfur contamination can occur when the feed gas contains a significant amount of mcrcaptans. Any disulfides formed will lend to coat the surface of the sulfur particles. If the sulfur is to be recovered as a salable product, special attention needs to be paid to the design of the overall system to avoid production of low-quality, disulfide-contaminated sulfur. Elimination of mercaptans and heavy hydrocar-... 

Following irradiation the specimen is highly active due to small amounts of carbon contamination from diffusion pump oil in the ion beam pipe. This gives a 10-min half-life product as a result of the reaction which... 

Pt within the first four surface layers, for the dean surface as well as the slightly C-contaminated surface. The MC simulations reveal the tremendous impact of even a modest carbon contamination. By the presence of C, the first substrate layer - for dean surfaces the preferred layer for Pt segregation - is more and more depleted of Pt, whereas the layers beneath are more and more enriched with Pt. The small coverages < 12.5% ML are not up to evicting the majority of Pt from the first layer, but a fair amount of Pt has to leave the first layer and occupy the layers beneath. 

The most common contaminants in produced gas are carbon dioxide (COj) and hydrogen sulphide (HjS). Both can combine with free water to cause corrosion and H2S is extremely toxic even in very small amounts (less than 0.01% volume can be fatal if inhaled). Because of the equipment required, extraction is performed onshore whenever possible, and providing gas is dehydrated, most pipeline corrosion problems can be avoided. However, if third party pipelines are used it may be necessary to perform some extraction on site prior to evacuation to meet pipeline owner specifications. Extraction of CO2 and H2S is normally performed by absorption in contact towers like those used for dehydration, though other solvents are used instead of glycol. 

In the absence of air, TEE disproportionates violently to give carbon and carbon tetrafluoride the same amount of energy is generated as in black powder explosions. This type of decomposition is initiated thermally and equipment hot spots must be avoided. The flammability limits of TEE are 14—43% it bums when mixed with air and forms explosive mixtures with air and oxygen. It can be stored in steel cylinders under controlled conditions inhibited with a suitable stabilizer. The oxygen content of the vapor phase should not exceed 10 ppm. Although TEE is nontoxic, it may be contaminated by highly toxic fluorocarbon compounds. 

The most overlooked hazard and contaminant is water (99). Water reacts with isocyanates at room temperature to yield both ureas and large quantities of carbon dioxide. The presence of water or moisture can produce a sufficient amount of CO2 to overpressurize and mpture containers. As Httle as 30 mL of water can result in 40 L of carbon dioxide which could result in pressures of up to 300 kPa (40 psi). For these reasons, the use of dry nitrogen atmospheres is recommended during handling. If a plant air system must be used, purification equipment, such as oil traps and drying beds, should be installed between the source and the isocyanate vessel. 

Also, the presence of strong bases, even in trace amounts, can promote the formation of isocyanurates or carbodiimides. In the event of gross contamination, the exothermic reaction can sharply increase the temperature of the material. Normally, the trimerization reaction occurs first and furnishes heat for the carbodiimide reaction. The carbodiimide reaction Hberates carbon dioxide and forms a hard soHd. The Hberation of carbon dioxide in a sealed vessel could result in overpressurization and mpture. 

Steelmaking. Large amounts of oxygen are used in almost aU aspects of the steelmaking process, largely to oxidi2e the principal contaminants, eg, carbon, phosphoms, and sUicon. 

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