Absorption infrared drying

Infrared drying, ceramics processing, 5 656 Infrared dyes, 9 500 Infrared emission spectroscopy, 23 142 Infrared inks, 14 315 Infrared lasers, 22 180 Infrared LEDs, 22 175, 176 Infrared measurements, in growing amorphous silicon, 22 130 Infrared microspectroscopy, 16 486 Infrared reflection-absorption spectroscopy (irras), 24 72, 114-116. See also IR spectra... 

Infrared drying Near-infrared spectroscopy Penetration of heat into the sample Specific absorption of near-infrared radiation (1400-1450,1920-1950 nm) by the water molecules of the food 10-25 min... 

The overtones of CH, OH, and NH valence vibrations appear in the near IR region. Therefore, foods give a large number of absorption bands that can be assigned to definite components and have intensities that correlate with the amounts of the constituents. As an example. Fig. 15.21 shows the absorption of wheat in the near IR region. The sample containing water absorbs at 1.94 pm in addition. Therefore, after subtraction of the absorption of dried wheat and after calibration, the water content can be determined. Other con-situents which can be determined in food by near-infrared (NIR) spectrophotometry are listed in Table 15.34. 

In the far-infrared region strong absorption by the water vapour normally present in air necessitates either continuously flushing the whole optical line with dry nitrogen or, preferably, evacuation. 

Infrared and Microwave Inks. These ate inks which have been formulated to absorb these radiant energies. The energy causes the inks to heat and dry through the partial evaporation of solvent. Absorption of the ink into a porous substrate can also be part of the overall drying mechanism with these inks. They have not found wide commercial success due to the variabiHty of the it absorption with ink color and the energy inefficiency of microwave systems in drying nonwater-based inks. 

An existing eontrol arrangement uses a PID eontroller to eontrol the temperature of the proeess air (measured by thermoeouples) and the dry elay moisture eontent measured by samples taken by the works laboratory. If this is out of speeifieation, then the proeess air temperature is raised or lowered. The dry elay moisture eontent ean be measured by an infrared absorption analyser, but on its own, this is eonsid-ered to be too noisy and unreliable. 

Infrared spectra for solid organic compounds are frequently obtained by mixing and grinding a small sample of the material with specially dry and pure potassi um bromide (the carrier), then compressing the powder in a special metal die under a pressure of 15 30 tonnes to produce a transparent potassium bromide disc. As the potassium bromide has virtually no absorption in the middle-infrared region, a very well-resolved spectrum of the organic compound is obtained when the disc is placed in the path of the infrared beam. 

In addition to the simple chemical methods for following these processes, infrared spectroscopy may also be used. In Fig. 9 is shown the spectrum of silica dried at 200°C before and after reaction with Zr(allyl)4- The characteristic absorption bands of the transition metal-allyl group are clearly displayed, also a significant reduction in the number of hydroxyl groups (3740 cm-1) is also clearly evident. 

Test 1. Carry out the infrared test according to the general procedure <197 K>. The infrared absorption spectrum of a potassium bromide dispersion of it, previously dried, exhibits maxima only at the same wavelength as that of a similar preparation of USP miconazole RS. 

Transfer a portion of topical powder, equivalent to about 100 mg of miconazole nitrate to a 50 mL beaker, disperse in 40 mL of methanol, and mix for a minimum of 5 min. Allow to settle for 5-10 min, and filter into 100-mL beaker. Evaporate on a steam bath to dryness. Dry the residue at 105 °C for 10 minutes the infrared absorption spectrum of a potassium bromide dispersion of the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Miconazole Nitrate RS. 

Test 2 Examine by infrared absorption spectrophotometry, according to the general procedure (2.2.24), comparing with spectrum obtained with primaquine diphosphate Chemical Reference Substance (CRS). Examine the substance as discs prepared as follows dissolve separately 0.1 g of primaquine diphosphate and the reference substance in 5 mL of water R, add 2 mL of dilute ammonia R and 5 mL of chloroform R and shake dry the chloroform layer over 0.5 g of anhydrous sodium sulfate R prepare a blank disc using about 0.3 g of potassium bromide R, apply dropwise to the disc 0.1 mL of the chloroform layer, allowing the chloroform to evaporate between applications dry the disc at 50 °C for 2 min. 

Molybdenum oxytetrachloride is a dark green crystalline compound with a melting point of 100 to 101°. Infrared absorption (KBr disk) has been used to establish the absence of OH- and H20 in verification of the anhydrous state. A broad band appears in the 970-em.-1 region and reveals molyb-denum-to-oxygen bonding. The oxychloride reacts with thoroughly dried Nujol so that satisfactory infrared spectra cannot be obtained with this as a dispersion medium. When exposed to light, molybdenum oxytetrachloride forms a brown film on the surface of the ampule. Since this film is not formed when the ampules are stored in the dark, molybdenum oxytetrachloride is concluded to be photosensitive. 

The sparingly water-soluble triethylammonium saltofBi2H122-is readily converted to the highly water-soluble sodium salt. A carefully weighed sample of the triethylammonium salt is treated with an exactly equivalent amount of standardized aqueous sodium hydroxide. The mixture is heated to effect solution and then boiled to expel the free triethylamine until the vapors are no longer basic. Evaporation to dryness then leaves a crystalline hydrate of Na2Bi2Hi2. The anhydrous salt is obtained by drying at 100°/1 n for 24 hours and has characteristic infrared absorption frequencies as a Nujol mull (exclusive of any frequencies coincident with Nujol) at 2470 (s), 1010 (w), 1070 (m), 770 (w), 727 (m),710 (m),and 700 (m) cm. 1... 

After the completion of the reaction, the solution was acidified to a pH of 4 with 2N sulfuric acid, followed by the addition of 50 ml of water. The solution was then extracted several times with ether. The extractant was dried over magnesium sulfate and the solvent was removed by evaporation at reduced pressure. Cold petroleum ether was then added to the resultant oily material to precipitate the product. The product was further washed with cold (10° C) petroleum ether and recrystallized several times from warm petroleum ether. The melting point of the final product was 73.5° C. Infrared spectrum of the product showed major absorption peaks relevant to the pure monomer (Figure 1). Under UV radiation, white flakes of the monomer solid turned deep blue (partial polymerization). 

Heavy residual fuel oils and asphalts are not amenable to gas chromatography and give similar infrared spectra. However, a differentiation can be made by comparing certain absorption intensities [52], Samples were extracted with chloroform, filtered, dried, and the solvent evaporated off at 100 °C for a few minutes using an infrared lamp. A rock salt smear was prepared from the residue in a little chloroform, and the final traces of solvent removed using the infrared lamp. The method, which in effect compares the paraffinic and aromatic nature of the sample, involves calculation of the following absorption intensity ratios ... 

The various combustion methods differ primarily in the method of measuring the carbon dioxide generated from the organic carbon. The first really sensitive carbon dioxide detector and the one still most used is the non-dispersive infrared gas analyser. The detecting element senses the difference in absorption of infrared energy between a standard cell filled with a gas with no absorption in the infrared, and a sample cell. Water vapour is the only serious interference, hence the carbon dioxide must be dried before any measurements are made. 

Procedure To the sample which contains 20-300 /xg of pertechnetate in 5-20 ml of solution, are added potassium perchlorate solution (2 ml, 1 mg KCIO per ml) and enough NaCl to make the solution approximately 1 M. The solution is heated and neutralized with ammonia. Pertechnetate is precipitated with aqueous 5 % tetraphenylarsonium chloride reagent. The precipitate is filtered, washed and dried, and a 2-mg portion is mixed with potassium bromide (300 mg). The mixture is pressed to form a clear disc by the usual technique. The infrared spectrum is recorded between 10 and 12 /x. The peak absorption is measured at 11.09 /X by the base-line technique. 

Ostrowska and Narebska noted an infrared continuous absorption in hydrated acid form Nafion 120 membranes that began at 3400 cm and extended toward low wavenumbers. This feature was not present in dry membranes and, based on the work of Zundel et al., was proposed to be due to the existence of Hs02 and Hg04 groups, in which there are easily polarizable hydrogen bonds. This paper by Ostrowska and Narebska is also useful, as it contains a number of band assignments for Nafion. 

PVI-1 and UDI have been Investigated as emtl-oxldatlon agents for Cu in dry air at elevated temperatures [ -30]. Fourier transform Infrared reflection-absorption spectroscopy TFT-IR RAS) was... 

For characterization, the polymer is dissolved in methylene chloride, precipitated again in methanol and dried at 50 °C in vacuum.The limiting viscosity number is determined in tetrahydrofuran at 20 °C and the molecular weight calculated (see Sect. 2.3.3.3.1). Additional information can be obtained by infrared spectroscopy.There should be no absorption of the OH-group at -3400 cm . 

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