Oxalate, oxidation

Oxalate Oxidation. Minimize the waste volume by oxidizing the H2C2O1 in the decanted supernate to C02(g) and H2O. 

In order to solve the problem of missing calcium oxalate accumulation, the first question to ask is whether or not the mineral is stable, i.e. is calcium oxalate able to spontaneously oxidize when in contact with the atmosphere If this is the case, the explanation is simple all the oxalate produced is rapidly oxidized as CO2, and therefore can be neither accumulated in the surficial environment nor in the fossil record. This assumes that the transformation of oxalate into CO2 must be complete and rapid in normal conditions, i.e. at 25 °C (298.15 K) and a pressure of 1 atm. This complete oxalate oxidation in solution is given by the following reaction ... 

Finally, it must be noted that oxalate oxidation by oxalate oxidase is a different means of degrading oxalate. By this mechanism, oxalate is completely oxidized to CO2 with concomitant production of H2O2. It has no trophic significance and its importance in oxalate cycling is not known. 

Jenni, B., Realini, L., Aragno, M. Tamer, A. U. (1988). Taxonomy of non H2-lithotrophic, oxalate-oxidizing bacteria related to Alcaligenes eutrophus. Systematic and Applied Microbiology, 10, 126-30. 

Inhibition of the Ce(TV)-oxalate oxidation by oxalate itself is interpreted in terms of the formation of higher complexes at high oxalate concentrations. If the 1 1 complex is the most reactive, its concentration is decreased when higher complexes are formed. For 10 M Ce(IV) the maximum rate of reaction with oxalate occurs with an oxalate concentration of 2 x 10 M. It seems reasonable to presume the formation of a Ce(IV) complex as the reactive intermediate in the oxidation of several other substances such as citric acid, mandelic add, benzilic acid, and polyamino-polycarboxylic acids. ... 

Whereas only 0.02 electron per indole unit was exchanged in the fast Fe oxidation process, long exposure of J,/-dopa melanin resulted in total consumption of two electrons. This observation was associated with an oxidative cross-linking step involving two hydrogen atoms (210). Unlike the Fe -oxalate oxidation, the potassium ferricyanide one in pH... 

C iJoride. Curomate. Qtrate. Cyanide. Perricyanide. Ferrocyaiiide. PIttorlde. Formate. Hydrate. Iodide. Malate. Nitrate. Oxalate. Oxide. Phospbete.. Silicate. Snocloate. Sulphate. Salphido. Tartrate. 

The analysis of the sediments at various depths of the aquifer was carried out by using different leaching agents for specific leaching fractions Na-dithionite and 0.2 M oxalate (oxides and hydroxides), 1 M HCl (acid volatile sulfides), acetic Cr(ll) for pyrite (Canfield et al., 1986 Cornell and Schwertmann, 1996 Hsieh and Yang, 1989). 

Method Based on the Ratios, Oxalate Oxide AND Oxalate Permanganate... 

Calcium oxalate monohydrate Sodium formate oxalic acid source Potassium oxalate oxidant, food L-Ascorbic acid oxidant, rocket fuels Perchloryl fluoride oxidant, selective... 

Fig. 5.19). The input barium titanyl oxalate powder has specific surface area 1 m /g. Therefore, the coefficient of refining rox/rut reaches 10 0 times on oxalate decomposition. Using more dispersed oxalate, however, is not reasonable due to the small particles coalescence on heating, and therefore, the oxalate grinding has almost no effect on the end of the BaTiOs synthesis. The morphology of nanoparticles depends on the gas release rate during the decay of oxalate, and hence the heating rate determines density of nucleation and nuclei coalescence probability. In addition, the increase in heating rate leads to a change in the mechanism of oxalate oxidation as described above. Structurally barium titanyl oxalate crystal transforms to the microreactor - particles of resin-like phase, size and activity of which can be flexibly controlled by the heating rate. The general view of the reactor is shown in Fig. 5.20.

Lu M-C, Whang C-W (2004) The role of direct oxalate oxidation in electrogenerated chemiluminescence of poly(4-vinylpyridine)-bound Ru(bpy)2CF/oxalate system on indium tin oxide electrodes. Anal Chim Acta 522(l) 25-33. doi 10.1016/j.aca.2004.06.042... 

Uranium compounds include acetates, carbonates, halides, nitrates, oxalates, oxides, phosphates, and sulfates. In broad terms uranyl (hexavalent, VI) compounds, which exist primarily as the U02 complex ion, tend to be the most soluble. The uranous (tetravalent, IV) compounds, such as UF4, are less soluble. Uranium oxides are the least soluble [3]. 

Figure 11.6 Dinuclear Mn-tmtacn complexes 6 and 23, and the proposed structure for the Mn-tmtacn/oxalate oxidation catalyst 22 p(= activated O to be transferred [99].

As intermediate products of thermal decomposition of hydrated R carbonates or oxalates, oxide carbonates R2O2CO3 are obtained for practically all Rs (Petru et al. 1966, Sawyer et al. 1972). Several metastable phases with defined crystal structures are formed as a function of temperature, before hexagonal (type-II) R2O2CO3 appears, with crystal structure (Christensen 1970, Attfield and Ferey 1989) [La202C03 P6 /mmc 407.55(6), 1595.7(1)] related to that of the hexagonal oxides of the early lanthanides. For R=La, Pr, Nd, Sm, and Gd, these oxide carbonates are relatively stable and can be isolated as single... 

Kanoufi, R, C. Cannes, Y. B. Zu, and A. J. Bard, Scanning electrochemical microscopy. 43. Investigation of oxalate oxidation and electrogenerated chemiluminescence across the liquid-liquid interface, J Phys Chem B, Vol. 105, (2001) p. 8951. 

Oxides from the hydrothermal decomposition of thorium oxalate. Oxides prepared by the hydrothermal decomposition of the oxalate [27] at 300°C in a closed autoclave were found to be markedly different in their characteristic properties from the thermally prepared materials. The precipitation temperature of the oxalate had no effect on the final shape or size, and all evidence of the original oxalate structure had disappeared. Sedimentation particle-size analyses indicated particle sizes between 0.5 and 1 micron. 

Fig. 10.6 Mn-tmtacn and proposed structures for Mn-tmtacn/oxalate oxidation catalyst (X = activated O" to be transferred [73]...

Cyclic voltammograms for 0.1 M phosphate buffer (pH 7.1) in the presence and absence of 500 pM oxalate, at as-deposited, oxidized and GC electrodes are shown in Fig. 3. In the presence of oxalate, a well-defined voltammogram was observed at 1.0 V vs. SCE for as-deposited i.e., hydrogen terminated diamond (Fig. 3a), whereas at oxidized diamond, the electrode response for oxalate totally disappeared (Fig. 12.3b), indicating the necessity of the hydrogen-terminated surface for the oxidation of oxalate. As shown in Fig. 12.3c, GC shows very low electroactivity towards oxalate oxidation. Further studies were carried out by use of H-terminated diamond electrodes. 

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