Decomposition Percentage Research Articles

Decomposition of the Iron, Aluminum, Zinc, and Copper Salts or Complexes of Some Microbial and Plant Polysaccharides in Soil

AbstractZinc, Copper, iron, and Aluminum salts or complexes of a series of bacterial and plant polysaccharides containing from 6 to 83% uronic acid units were prepared. The rate of decomposition of the metal‐polysaccharide complexes or salts and the original polysaccharide preparations was determined in Greenfield sandy loam. Some or all of the metals exerted marked effects on decomposition rate and percentage decomposition at 8 weeks of the majority of polysaccharides tested. Specific effects of the metals depended on the polysaccharide. Zinc and Al exerted very little influence on decomposition of Azotobacter chroococcum polysaccharide for example, while Cu and Fe reduced decomposition by about 50%. A much smaller percentage of Zn, on the other hand, reduced decomposition of Karaya gum from 67% to 0 in one test and to 3% in a repeat trial. The Cu‐salt of Azotobacter indicus polysaccharide was highly resistant to decomposition. After 8 weeks, 3% had decomposed compared to 29, 32, 16, and 16% for the original polysaccharide and the Al, Zn, and Fe complexes, respectively. With the exception of the Al combined with the Arthrobacter viscosus polysaccharide, all of the metals sharply reduced decomposition of A. viscosus polysaccharide and alginic acid but exerted very little effect on polysaccharides from Chromobacterium violaceum and a Bacterium sp. When added directly to the soil in concentrations equivalent to that in the metal‐A. chroococcum polysaccharide complexes (75% uronic acid), the metals exerted no effect on decomposition of Bacillus subtilis fructosan.

Decomposition of organic matter and mineralization of nitrogen in brookston silt loam and alfalfa green manure

C14 and N15 doubly labelled alfalfa tissue at addition rates of 5 and 1 ton per acre was incubated in the laboratory for 72 days with virgin and cultivated Brookston silt loam. The alfalfa tissue was more extensively decomposed in the virgin soils than in cultivated soil, but retention of tissue carbon was not affected by rate of addition. Percentage decomposition of organic matter in the virgin soil was greater than that in the cultivated soil. Addition of alfalfa tissue reduced decomposition of soil organic matter in proportion to the rate of addition and resulted in a gain of carbon in the incubation mixture. No “priming action” was noted. An increase in the rate of tissue addition caused an increase in the amount of nitrogen mineralized from the tissue but had little effect on the amount of nitrogen mineralized from the soil. Nitrogen mineralized from the soil organic matter was preferentially immobilized during the latter part of the incubation period. It appears that the organic matter content of the soil as well as the rate of tissue addition may regulate the “priming action” of green manures.

KINETICS AND MECHANISMS OF THE PYROLYSIS OF DIMETHYL ETHER: II. THE REACTION INHIBITED BY NITRIC OXIDE AND PROPYLENE

The thermal decomposition of dimethyl ether, inhibited by nitric oxide and by propylene, was studied in the temperature range of 500 to 600 °C. About 1.5 mm of nitric oxide gave maximal inhibition, the rate then being approximately 8% of the uninhibited rate. With propylene, approximately 70 mm gave maximal inhibition, the rate being slightly higher than that using nitric oxide (~12.5% of the uninhibited rate). In both cases the degree of inhibition was independent of the ether pressure. In the maximally inhibited regions both reactions are three-halves order with respect to ether pressure. As the pressure of nitric oxide was increased beyond 10–15 mm, the overall rate increased, and in this region the reaction is first order with respect to both nitric oxide and ether. A 50:50 mixture of CH3OCH3 and CD3OCD3, with enough NO to ensure maximum inhibition, was pyrolyzed. Even at very low percentage decomposition the CD3H/CD4 ratio was approximately the same as that in the uninhibited decomposition, proving that the inhibited reaction is largely a chain process. Detailed inhibition mechanisms are proposed in which the inhibitor is involved both in initiation and termination reactions.

Decomposition of Carbon Dioxide by Ionizing Radiation. Part I

The irradiation of gaseous carbon dioxide with radon or in a nuclear reactor, produces about 0.1 percent decomposition of primarily dissociated carbon dioxide, correlating with previous results in the literature. The irradiation of solid carbon dioxide with radon produces carbon monoxide and oxygen with a G value of 9 to 10. The irradiation of gaseous carbon dioxide, containing a small amount of nitrogen dioxide, by radon or in a nuclear reactor, produced carbon monoxide and oxygen, with a G value of 9 to 10. Percentages as small as 0.5 percent of nitrogen dioxide are sufficient to stop the back reaction to carbon dioxide. A new mechanism has therefore been proposed for the ineffectual decomposition of carbon dioxide by ionizing radiation, and the effective decomposition when nitrogen dioxide is present. With the proposed mechanisms, the classical experiments of Lind, the carbon monoxide oxidation and the carbon monoxide decomposition, are quantitatively explained.

THE KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: III. PROPANE

The kinetics of the thermal decomposition of propane has been investigated over a temperature range from 551° to 602 °C. The limiting high pressure first order rate constants are given by[Formula: see text]The first order rate constants fall off strongly with increasing percentage decomposition, and the rate decreases with decreasing pressure in a manner similar to the rate decrease in the decomposition of the butanes.Analyses of the products of reaction at various stages show them to be independent of temperature over the range examined, but to be affected by the initial pressure. This effect is undoubtedly due to the secondary hydrogenation of some of the initial products. The analytical results are in excellent agreement with those of Frey and Hepp.

Dissociation of Nitrous Oxide in the Glow Discharge

IN a recent paper, Kueck and Brewer1 describe experiments made on the dissociation of nitrous oxide in the ‘glow’ discharge. Using a special dis position of electrodes which eliminates anode glow and positive column, they find, with fields of the order of 2,000 volts/cm., over a pressure range 2–5mm., that the initial decomposition rate is practically independent of the initial pressure. Similar results for both nitrous oxide and ammonia have been described by Hinshelwood and Hutchinson2, who, using a method which gives essentially the integrated dissociation throughout all parts of a normal glow discharge, state that for weak discharges the absolute amount of decomposition tends to be independent of the initial pressure. They observe, however, that for more intense discharges “the amount of decomposition becomes proportional to the pressure, i.e., the percentage decomposition is now independent of the initial pressure”. This they term the “unimolecular state”. Unfortunately, they give little data as to the potentials employed.