Hydrocarbons batch sampling

Evolved gases were monitored continuously for 02, C02, NOx, CO, and total hydrocarbons (THC) by a continuous emission monitoring system (CEMS). Batch samples of the offgases were also taken and analyzed for NH3, HCN, residual energetic materials, volatile organic compounds, and N2. The batch samples were collected over the entire duration of each run, and the single value reported represents the average concentration for the whole run. 

Soot samples were obtained by use of a nitrogen-quench, porous-walled probe and Nucleopore filters (7). Gas phase hydrocarbons were collected by the porous probe as batch samples and analyzed by standard FID gas chromatography. Thermal measurements included gas temperature by radiation-corrected bare wire thermocouple, and soot temperature by Kurlbaum reversal (9, 10) and two color pyrometry (11). 

The conventional approach to solvent extraction is the batch method. Early work with this method was hampered by the low concentration of the compounds present and the relative insensitivity of the methods of characterization. Thus lipids and hydrocarbons have been separated from seawater by extraction with petroleum ether and ethyl acetate. The fractionation techniques include column and thin-layer chromatography with final characterisation by thin-layer chromatography, infrared, and ultra-violet spectroscopy and gas chromatography. Of these techniques, only gas chromatography is really useful at levels of organic matter present in seawater. With techniques available today such as glass capillary gas chromatography and mass spectrometry, much more information could be extracted from such samples [20]. 

A second system, the removal of volatiles by vacuum, can be set up in two ways either as a flow-through or as a batch process. As a flow-through process, the sample is drawn continuously through the system, and the gases taken off by the vacuum pass through a sampling loop. Periodically, the material in the loop is injected into the gas chromatograph. In this manner it is possible to derive almost continuous profiles of volatile hydrocarbon concentrations [19]. 

Several samples of the hydrocarbon phase were obtained during the course of each batch run to determine how the composition was changing. As a run progressed, LE s, DMH s, and TMP s, were the major compounds produced. Several heavy end hydrocarbons decreased toward zero as the run progresses hydrocarbons 24, 25, and 30 as defined earlier (3) in particular disappeared as a result of reactions with Isobutane. These reactive hydrocarbons were presumably C, or heavier olefins. There were however large amounts of unreaccive heavy ends, which are heavy Isoparaffins. Calculations Indicated that the heavy ends in the alkylate were produced for the most part during the first-step reactions. 

The dynamics of methane, propane, isobutane, neopentane and acetylene transport was studied in zeolites H-ZSM-5 and Na-X by the batch frequency response (FR) method. In the applied temperature range of 273-473 K no catalytic conversion of the hydrocarbons occurred. Texturally homogeneous zeolite samples of close to uniform particle shape and size were used. The rate of diffusion in the zeolitic micropores determined the transport rate of alkanes. In contrast, acetylene is a suitable sorptive for probing the acid sites. The diffusion coefficients and the activation energy of isobutane diffusion in H-ZSM-5 were determined. 

The pyrolysis process for waste recycling is frequently done at larger scale than analytical pyrolysis. However, analytical pyrolysis studies are performed independently for the understanding and the optimization of such processes [10,16-19]. Also, model mixtures can be used in parallel with real samples. For example, the comparison of thermal degradation products from real municipal waste plastic and model mixed plastics can help understand the compounds generated in waste incinerators. In one such study [20], analytical pyrolysis of real municipal plastic waste obtained from Sapporo, Japan and model mixed plastics was carried out at 430 °C in atmospheric pressure by batch operation. The chlorinated hydrocarbons found in degradation liquid products of poly(ethylene)/poly(propylene)/ poly(styrene)/poly(vinyl chloride) and other polymeric mixtures were monitored. It was determined that the presence of poly(ethylene terephthalate), in addition to chlorinated plastics in the waste, facilitates... 

Methods of Liquid—Liquid Extraction. Most methods described for LLE are the batch type (12, 13). This is surprising since continuous extraction has an obvious advantage over serial extraction because larger sample volumes are extracted. Kahn and Wayman (25) and Goldberg et al. (26) have described continuous LLE systems for lighter and heavier than water extractions, respectively. Such extractors are used with multiple chambers and internal solvent recycling. Kahn and Way-man successfully recovered chlorinated hydrocarbon pesticides with 96-100% efficiency in a 3-chamber system with petroleum ether (25). An average residence time of 45 minutes per chamber at a 1 1 solvent to water phase ratio was used on a 20-liter sample of less than 400 ppb concentration. 

The products obtained from thermal cracking of plastics depend on the type of plastics, feeding arrangement, residence time, temperatures employed, reactor type, and condensation arrangement [42]. Reaction temperature and residence time have strong influence on the yield of pyrolysis products and the distribution of their components for plastic samples. Jude et al. conducted smdies on thermal cracking of LDPE in a batch reactor resulted in the production of a broad range of hydrocarbon compounds where the yield of aromatics and aliphatics (olefins and paraffins) deeply depended on the pyrolysis temperature and residence time. 

The risk of contamination must also be considered when a diffusive sampler is used to obtain air samples for determining volatile organic compounds. Thus, benzene, n-tetradecane. n-pentade-cane, n-hexadecane, n-heptadecane. and dioctyl phthalate [158], along with trichloromethane, 1.1,1-trichloroethane. trichloroethene, and tetrachloroethene [159] have all been detected in extracts from unexposed diffusive samplers. The measured concentrations varied from batch to batch, ranging from 0.005 pg to 0.14 pg per diffusive sampler in the case of the chlorinated hydrocarbons [159], and from 0.1 - 2.6 pg per diffusion collector for the aliphatic hydrocarbons and dioctyl phthalate [158]. 

The second application of NIR spectroscopy in the analysis of intact tablets from clinical batches was published in a 1994 paper by Aldridge et al. [123]. A NlRSystems Model 6500 with a custom sampling configuration was used for spectral collection of the blister-packed samples, and the second derivative spectra were used in the analysis. Spectralon was used for reference. Although certain peaks in the NIR spectra were attributed to the hydrocarbon functionality of the packaging material, the spectral features of the tablets within were clearly visible. 

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