Amorphous organic residues

Dining vacuum evaporation of an aqueous mixture of unspecified mixed metal nitrates and citric acid, the amorphous solid exploded when nearly dry. This was attributed to oxidation of the organic residue by the nitrates present, possibly catalysed by one of the oxides expected to be produced. 

Humus, which has lost all the visible features of the organic residues from which it formed, is subdivided into amorphous brown-colored polymers according to the scheme depicted in Figure 2.21. The polymers, termed humic substances, can be further separated (operationally, if not intrinsically) into humic acid, fulvic acid, and humin, according to their solubility in strong acid and base. Aqueous sodium hydroxide extracts humic and fulvic acid from soils, leaving the humin unextracted. Acidification of this dark-colored extract then causes the humic acid to precipitate, while the fulvic acid remains soluble. 

A further experiment was carried out to study the possible role of tars in the oxidation process which transforms the imine into the oxime by 0-insertion. Indeed, no decisive data are available to exclude any influence of the presence of tars on the catalyst surface on the reaction of oxidation of the imine to oxime. On the other hand, the many evidences seem to indicate a possible correlation between the oxidation power exhibited by the simple amorphous silica samples and the presence of organic residues irreversibly adsorbed. In particular, an important indication is the extrapolation of the rate of formation of the oxime at t=0 h. The value obtained is about zero suggesting that the pure silica can not catalyze the oxime formation. In order to confirm this hypothesis, other catalytic tests were carried out under standard conditions and the first hour of reaction was studied in more detail. The results, reported in figure 6, showed that the rate of formation of the oxime at very beginning of the test with the time-onstream is really null. This datum demonstrates that the simple silica can not generate the oxime and that the oxidizing power is related to the presence of the tars and that the activation process which takes place in the first 10 h of the reaction is due to the increase of the tars. 

Soluble organically complexed Carbonate Mn oxide Insoluble Organic Amorphous Fe oxide Crystalline Fe oxide Residual... 

General Aspects and Heat Treatment Effects. After him formation, for most of the hlms aimed at electronic applications (other than amorphous oxides, such as Si02), the hlms are subjected to a heat treatment process for removal of residual organic species (entrapped solvent as well as the organic constituents associated with the precursor species), densihcation (elimination of residual porosity and structural free volume in the him), and crystallization. 

Most organic archaeological residues exist as amorphous biological remains in the archaeological record, but since they lack the macroscopic cellular structure present in seeds, wood, leather, or pollen they cannot be recognized by traditional microscopic techniques. Typical residues include food deposits surviving (either visibly on the surface, or invisibly absorbed... 

Tab. 1.2 Summary of typical purification techniques for CNTs. a Treatment can remove metal catalyst residues. b Carbon residues (e.g. amorphous or organic aromatic debris).c Purification introduces covalently bonded functional groups. d Only if not covered with carbon or encapsulated within CNT. e Only amorphous carbon around metal particles. From [39] with kind permission from ACS Publications.

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