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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
‘Hot atom’ chemistry is important to obtain a suitable chemical form of the radioactive product, especially when working with gas and liquid targets. Solid targets are usually dissolved and chemically processed to obtain the wanted chemical form for further labelling.
Spray Drying and Pharmaceutical Applications
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Metin Çelik, Pavan Muttil, Gülşilan Binzet, Susan C. Wendell
Internal mixing nozzles in general require less air than external mixing nozzles in order to produce droplets with the same mean droplet diameter. This is due to a higher energy transfer between the air and the liquid, as the atomization takes place under pressure difference inside the mixing chamber because the air and liquid pressures become equal first at the mixing chamber outlet. This is especially an advantage during nozzle scale-up where the increase in gas-to-liquid flow rate with scale is much less than for external mixing nozzles. The downside is, however, that over time, the impact surface becomes eroded and affects the spray droplet size pattern.
Value-Added Products and Bioactive Compounds from Fruit Wastes
Published in Megh R. Goyal, Arijit Nath, Rasul Hafiz Ansar Suleria, Plant-Based Functional Foods and Phytochemicals, 2021
Ranjay Kumar Thakur, Rahel Suchintita Das, Prashant K. Biswas, Mukesh Singh
Supercritical fluid extraction (SFE) is performed by applying temperature and pressure that transforms the gas in the supercritical fluid to a point, where the gas and liquid phases cannot be distinguished. The extraction is fast, selective without any need of further cleaning and can be performed with small samples [123]. It is a mass transfer operation, with convection occurring between the solid surface and fluid phase [157]. The steps in the process are: (a) solubilization of the compounds, which are in the solid matrix and subsequently, and separation in the supercritical solvent, (b) the solvent passes through the packed bed and extracts solubilized compounds from the matrix, and (c) solvent then exits the extractor and by pressure reduction and temperature increase, it transforms to a solvent-free extract [158].
Toxicological and ecotoxicological properties of gas-to-liquid (GTL) products. 2. Ecotoxicology
Published in Critical Reviews in Toxicology, 2018
Graham F. Whale, James Dawick, Christopher B. Hughes, Delina Lyon, Peter J. Boogaard
Gas-to-liquid (GTL) products are synthetic hydrocarbons produced from natural gas as a feedstock. The basic chemistry of the GTL process was developed in 1925 in Mülheim an der Ruhr (Germany) at the Kaiser Wilhelm Institut für Kohlenforschung by Franz Fischer and Hans Tropsch and is known, after the inventors’ names, as the “Fischer–Tropsch process”. This process involves the synthesis of higher hydrocarbons from a simple carbon source, via so-called synthesis gas (or “syn-gas”, a mixture of carbon monoxide and hydrogen), using a catalyst. For GTL products, the main carbon source is methane, usually from so-called stranded gas, but it can also be methane obtained from biomass digestion or from coal gasification. The methane is converted, by a process called steam-reforming, to “syn-gas”, per the following reaction formula: H2O + CH4 → CO +3H2. The “syn-gas” produced in this process is subsequently catalytically converted to a range of saturated hydrocarbons, per the following reaction formula: (2n + 1) H2 + n CO → CnH(2n+2) + n H2O. The saturated hydrocarbons formed are primarily linear alkanes, with increasing amounts of branched (methyl-groups) alkanes if the chains get longer. In addition, small amounts of cycloalkanes (branched cyclopentanes and cyclohexanes) may be formed as the reaction prolongs. Essentially, the process yields a synthetic crude oil that is made up of a wide variety of alkanes but that is essentially free of unsaturated or aromatic compounds. In addition, in contrast to petroleum crude no sulfur-, oxygen-, or nitrogen-containing compounds are present in GTL synthetic crude from which the GTL products are derived.