Pyrolysis curve

Thermogravimetry may be used to determine the composition of binary mixtures. If each component possesses a characteristic unique pyrolysis curve, then a resultant curve for the mixture will afford a basis for the determination of its composition. In such an automatic gravimetric determination the initial weight of the sample need not be known. A simple example is given by the automatic determination of a mixture of calcium and strontium as their carbonates. 

C. Other useful substances to study. The following substances show interesting pyrolysis curves and an assessment of the purity of these materials may be investigated ... 

Figure 5. Evolution of chemical water during pyrolysis. (Curves) nonisothermal single reaction, first-...

Figure 3.70 Steady state ring-disk polarization in 0.1 M NaOH before (A) and after pyrolysis curves for O2 reduction on a thin porous coating 800 °C, 2 h in Ar (B). Electrode cross-sectional electrode containing 4.7% w/w CoTMPP XC-72 area, 0.196cm2, co = 2500rpm, room (solid triangles), 4.8% w/w (FeTMPP)20 XC-72 temperature, Au Ering = +0.1 V versus SCE, (solid circles), 4.4% w/w H2TMPP XC-72 (solid N = 0.38. squares) and Vulcan XC-72 carbon (open circles)...

There are four major decomposition reactions that take place during the pyrolysis curve 1, water and phthalic anhydride volatize and a residue to dipotassium phthalate is formed. K2C8H404 curve 2, the latter compound decomposes to form potassium carbonate and carbonaceous material curve 3, the carbonaceous material loses mass slowly and finally burns giving a residue to K2C03 and curve 4, the potassium carbonate decomposes with the evolution of carbon dioxide, while the K20 formed reacts with the porcelain crucible sample holder. 

A developed TLC plate for TNT (93) showed that the TNT and volatile impurities begin to vaporize and appear on the TLC plate between 125 and 135°C, corresponding to the first appearance of gas in the pyrolysis curve. Most of the TNT vaporizes, and is collected undecomposed since it is a relatively stable compound thermally. Within the temperature range where TNT dissociates exothermally, as indicated by the DTA curve, the following products appear 2,4.6-trinitrobenzyl alcohol ITNB-OH) 4.6-dinitroan-thranil (DNA) 1.3.5-trinitrobenzene (TNB) 2.4,6-trinitrobenzoic acid (TNB-a) and a trace of an unidentified compound. The combination of the precision of the TLC method with the characteristic colors of Ihe spray reagent make it relatively simple to identify all the major components found. 

Pyrolysis and atomization curves of manganese are shown in Fig. 2. The pyrolysis curve was obtained using 2300°C as the atomization temperature. The selected pyrolysis temperature for Mn in THFA is about 1600°C. Using this pyrolysis temperature, the optimum atomization temperature corresponds to 2100°C. These pyrolysis and atomization temperatures do not correspond to the THGA suggested temperatures [21], as the furnace design is different and the rate of the vaporization process is also different. Some loss on manganese is observed above 2100 C, due to the volatility of the atomic species at hi temperature. 

The themogramivetric curves for the preceeding data are shown as Figures 13 and 14. Figure 13 shows the family of TG pyrolysis curves produced under the stated TG conditions for varying amounts of sytrene in the SBR blend. It is observed that the decompositon temperatures are similar as might be expected providing the pyrolysis conditions are kept constant. 

A common problem in ETAAS is that analyte volatility depends on the compound in which it is present—chlorides are usually much more volatile than sulfates or phosphates— and in general on the concomitants. A pyrolysis curve established for one sample type may therefore not be valid... 

FIG. 5. Pyrolysis-atomization curves for electrothermal A AS. A = integrated absorbance signal plotted against applied pyrolysis temperature (pyrolysis curve) B = integrated absorbance signal plotted against atomization temperature (atomization curve). 1 = maximum pyrolysis temperature 2 = lowest temperature of complete volatilization 3 = appearance temperature 4 — optimum atomization temperature. (From Ref. 23 by permission.)... 

Pyrolysis curves of lead derivatives, 1) PbO from the metal. 

Pyrolysis curves of lead derivatives. 9) Sulphide. 10) Sulphl 11) Hydrogen phosphate. 12) Carbonate. 13) Basic thiocyanate. 14) Oxalate. 15) Phthalate. Reproduced from C. Duval, "Thermo-gravimetric Analysis". Elsevier Publishing Co., Amsterdam (1953) p. 466. 

Pyrolysis curves of lead complexes with 24) Ihlonallde. 

Figure 13.23 DTA-EGD-GC characteristic pyrolysis curves of anthracite coal...

Los Alamos National Laboratory, was used for impact experiments. The samples yielded smooth DTA and pyrolysis curves indicating no peaks or changes below their normal temperatures of decomposition. On washing the control TATB samples with acetone, no ragged holes or micro-cavities appeared under the SEM due to impurity extraction. The samples of TNT, HMX, RDX and other explosives used, were also the best samples available from various laboratories. 

Fig. 9.3. Coloration stabilization during PVC pyrolysis. Curve 1 efficiency of lead-based stabilizers curve 2 efficiency of cadmium-based stabilizers ...

The enthalpy and temperature data in Table 3.13 is intended to identify the main groups of minerals from an available TGA or DTA diagram from coal pyrolysis or low-temperature ash (ashing below 380 °C). If, for example, in a pyrolysis curve from TGA, the mass change per time peaks at 670 °C, it can be concluded that MgCOs is part of the coal and a part of the measured ultimate carbon content will require heat to be gasified. To quantify the effect, the carbonate CO2 should be determined for that sample. 

The first step of a method development in GF AAS is usually an optimization of the pyrolysis and atomization temperatures by establishing pyrolysis and atomization curves using a matrix-free calibration solution as well as at least one representative sample or reference material. The pyrolysis curve exhibits the integrated absorbance signal obtained at a fixed atomization temperature as a function of the pyrolysis temperature, as shown schematically in Figure 8.13. 

Figure 8.13 Typical pyrolysis curve for GF AAS the integrated absorbance obtained at the optimum atomization temperature is plotted against the pyrolysis temperature...

Vale et al. [143], analyzing nickel in crude oil using LSGFAAS, observed an unusual slight increase in sensitivity in the pyrolysis curves for pyrolysis temperatures below 1000 °C for crude oil, whereas no such increase was found for the calibration solutions, as shown in Figure 8.44. Originally this increase in sensitivity was interpreted as an arti-... 

Figure 8.44 Pyrolysis curves for a 2.6 ng nickel standard solution (Ni salt of 2-ethylhexanoic acid) in base mineral oil, and a crude oil sample, diluted with IBMK and as oil-in-water emulsions, respectively, using LS GF AAS...

Figure 8.48 Pyrolysis curves for nickel (dashed hue) and vanadium (solid line) in a Brazilian crude oil sample as oil-in-water emulsion, using HR-CSGFAAS, measured at 232.003 nm and 318.540 nm, respectively...

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