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Formation and Sorption Properties of Iron Oxides and Manganese Oxyhydroxide
Published in D.S. Sofronov, K.N. Belikov, M. Rucki, S.N. Lavrynenko, Z. Siemiątkowski, E. Yu. Bryleva, O.M. Odnovolova, Synthetic Sorbent Materials Based on Metal Sulphides and Oxides, 2020
D.S. Sofronov, K.N. Belikov, M. Rucki, S.N. Lavrynenko, Z. Siemiątkowski, E. Yu. Bryleva, O.M. Odnovolova
Interaction of the manganese chloride and potassium permanganate in neutral environment pH 7 caused the formation of spherical particles with diameters 0.4–0.7 μm. IR spectrum of this product revealed absorption bands at 560, 513, and 458 cm−1 as it is seen in Figure 2.22. Comparative analysis of this spectrum with the ones belonging to the samples precipitated in alkaline environment indicated that the shift of absorption band from 443 to 458 cm−1 accompanied by its intensity decreases. The absorption band at 560 cm−1 is attributed to Mn–O bond vibration either in Mn2O3 or in MnO2 molecules. It can be assumed that neutral environment pH 7 results with decreased formation of manganese oxyhydroxide and thus increased proportion of obtained oxides.
Colloidal Chemical Properties of Biological Nanosystems
Published in Victor M. Starov, Nanoscience, 2010
Z. R. Ulberg, T. G. Gruzina, N. V. Pertsov
The electron microscopic images (Figure 11.6) demonstrate the formation of such a dispersed phase during the process when metal ions are adsorbed from solution by the cells. According to x-ray analysis data, during the process of sorption, colloidal particles of the metallic gold (picture a) and silver, which are mixed with silver oxide (picture b), precipitate. As for copper and the manganese (pictures c and d), the phase content analysis allows assuming that, in this case, the solid particles yielded by the cells are oxides or hydroxides of relevant metals. Formation of a re-crystallized dispersed phase is more typical for inactivated rather than for living cells. The process of dendritic crystallization in manganese chloride solutions (picture d) may serve an example of the above behavior.
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
The molecular organization of a thylakoid membrane is shown in Fig. 5. The spectral characteristics of PS II indicate that the primary electron donor is the dimer of chlorophyll P680 with absorption maxima near 680 and 430nm. Water can be oxidized by an oxygen-evolving complex (OEC) composed of several chlorophyll molecules, two molecules of pheophytin, plastoquinol, several plastoquinone molecules, and a manganese-protein complex containing four manganese ions. The OEC is a highly ordered structure in which a number of polypeptides interact to provide the appropriate environment for cofactors such as manganese, chloride, and calcium, as well as for electron transfer within the complex. Figure 6 shows the electronic equivalent circuit of PS I and PS II.
Minreview: Recent advances in the development of gaseous and dissolved oxygen sensors
Published in Instrumentation Science & Technology, 2019
Q. Wang, Jia-Ming Zhang, Shuai Li
The indirect Winkler method uses residual iodine and the replacement of iodine methods. This procedure must be in neutral or weak acid solution. High acidity oxidizes iodide, which promotes the decomposition of sodium thiosulfate. In highly alkaline solution, disproportionate reactions occur with iodine. The surplus iodine method uses excess iodine as reducing substances. The first reaction involves reducing substances and excess iodine, while the remaining iodine with a sodium thiosulfate back-titration, and amount of sodium thiosulfate is used to determine the concentration. The determination of water-soluble oxygen is replaced by the Winkler method. The basic procedure uses manganese chloride and sodium hydroxide to induce manganese hydroxide precipitation, water-soluble oxygen precipitation into a brown precipitate, followed by reaction with sulfuric acid to produce manganese sulfate. Lastly, the potassium iodide is oxidized to iodine, and the resulting iodine is titrated with sodium thiosulfate.