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Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Chromate and dichromate may be detected by diphenyl carbazide depending on the oxidizing action of the anion. That is, chromate must be oxidized to dichromate to be detected. This oxidation may be accomplished by adding sodium hydroxide and sodium peroxide to the unknown solution. Mix a saturated diphenyl carbazide solution in 90% alcohol and then saturate with potassium thiocyanate. Add a few grains of potassium iodide and mix well. Add a drop of this solution to a reaction paper. Next add a drop of the sample solution and then add a drop of dilute sulfuric acid. A violet color appears if dichromate from the original chromium source is present. (Red indicates magnesium.)
Biologic Biomaterials: Tissue-Derived Biomaterials (Collagen)
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
33.1.2.2.2 Ion and Macromolecular Binding Properties In the native state and under physiological conditions, a collagen molecule has only about 60 free carboxyl groups (Li et al., 1975). ese groups have the capability of binding cations such as calcium with a free energy of formation for the protein –COO-Ca2+ of about 1.2 kcal/mol. is energy is not large enough to compete for the hydrogen bonded salt-linkage interactions, which have a free energy of formation of about −1.6 kcal/mol. e extent of ion binding, however, can be enhanced in the presence of lyotropic salts such as potassium thiocyanate (KCNS), which breaks the salt linkages, or by shiing the pH away from the isoelectric point of collagen. Macromolecules can bind to collagen via covalent bonding, cooperative ionic binding, entrapment, entanglement, and a combination of the above. In addition, binding of charged ions and macromolecules can be signicantly increased by modifying the charge prole of collagen as described previously. For example, a complete N-acetylation of collagen will eliminate all the positively charged ε-amino groups and, thus, will increase the free negatively charged groups. e resulting acetylated collagen enhances the binding of positively charged ions and macromolecules. On the other hand, methylation of collagen will eliminate the negatively charged carboxyl groups and, thus, will increase the free positively charge moieties. e methylated collagen, therefore, enhances the binding of negatively charged ions and macromolecules (Li and Katz, 1976).
Tracers
Published in Werner Käss, Tracing Technique in Geohydrology, 2018
To determine in which probes flood water reemerged, Dolak (1969) carried out a tracing test with, among others, potassium thiocyanate. With an injection amount of 4 kg KSCN, the detection over a distance of between 190 and 540 m in several probes was possible.
Mild and efficient desulfurization of thiiranes with MoCl5/Zn system
Published in Journal of Sulfur Chemistry, 2022
Byung Woo Yoo, Yeong Jin Lee, Jeong Won Shin
The reagent system was readily generated by the reaction of molybdenum(V) chloride with zinc. The addition of zinc powder to a stirred solution of molybdenum(V) chloride in THF gave a dark blue suspension with a slightly exothermic process; a kind of low-valent molybdenum complex may be formed [17]. Encouraged by the convenient generation of low-valent molybdenum complexes, we have investigated the reactions of MoCl5/Zn system with a variety of thiiranes. Gratifyingly, we observed that all substrates can be efficiently desulfurized to alkenes in high isolated yields. The thiiranes in Table 1 are prepared by reaction of the corresponding epoxides with potassium thiocyanate [23]. In an attempt to characterize the low-valent molybdenum species that presumably participates in the desulfurization process, a control experiment was carried out with MoCl5 in the absence of zinc metal under the present condition, which failed to yield any desired product. It is obvious that a combination of MoCl5 and zinc metal is indispensable for the success of the reaction. The effect of the relative amounts of molybdenum(V) chloride to zinc on the reaction was significant as can be seen in Table 2. The optimum molar ratio of thiirane to MoCl5 to zinc (1:1:2) is found to be ideal for the complete conversion of thiirane into alkene in THF at room temperature, while with lesser amounts the reaction remains incomplete.
Removal of Cr(VI) with nano-FeS and CMC-FeS and transport properties in porous media
Published in Environmental Technology, 2020
Huiping Yang, Mei Hong, Shaoyin Chen
The concentration of Cr (VI) was determined using the diphenylcarbazide colorimetric method. Total iron determination was determined using potassium thiocyanate colorimetry method. The pH value was determined by YSI pH100 pH metre. The morphology and size of the prepared materials were observed by transmission electron microscopy (JEOL JEM-2010, Japan) with a voltage of 120 kv. The main components of the prepared materials were determined by X-ray diffractometer (D/MAX-2550X, Japan) under conditions of 40 kV, 100 mA by using a Cu target. The scanning diffraction angle range was 10–90 degrees, the scanning speed was 2°/min. X-ray photoelectron spectroscopy was used to identify the reduced products and characterize surface features. X-ray photoelectron spectroscopy (AXIS-UL TRA DLD UK KRATOS) was with an excitation source of A1Kα (1486.6 eV), and an X-ray beam diameter of 500 μm. Elemental binding energy referred to the C 1 s standard (248.6 eV). Zeta Potential of Nano-FeS, CMC-FeS Suspensions and quartz sand was measured by Zetasizer Nano ZS90.
Selective and efficient desulfurization of thiiranes with Mo(CO)6
Published in Journal of Sulfur Chemistry, 2020
We have investigated the reaction of Mo(CO)6 with a broad range of structurally diverse thiiranes and found that they can be conveniently desulfurized to the corresponding alkenes in high yields. In an effort to assess the scope and generality of this reagent, the reaction was examined with thiiranes bearing other potentially labile functional groups. This new methodology is highly chemoselective, tolerating various functional groups such as chloro, bromo, fluoro, ester, methoxy, ether and keto under the reaction conditions. The procedure is equally applicable to aromatic and aliphatic thiiranes under optimized reaction conditions and was not affected by steric hindrance. The isolated yield was independent of the nature of the substituents. Thus, high yields was observed for thiiranes with either electron-withdrawing or electron-donating substituents on the aromatic ring with no obvious preference on the reactivity. The representative results of the reactions are summarized in Table 1. Starting materials have been synthesized by reaction of the appropriate epoxides with potassium thiocyanate [23]. Halogen-substituted styrene thiiranes were clearly desulfurized to the corresponding halostyrenes without any evidence of the undesired dehalogenation side reaction (entries 2, 3 and 4). Carbonyl and ether groups also remained unaffected during desulfurization of the corresponding thiiranes by this procedure (entries 7 and 11).