Carbon dioxide evolution

In situations where conserved internal markers caimot be used, such as in spills of essentially pure compounds, the evidence for enhanced biodegradation may have to be more indirect. Oxygen consumption, increases in microbial activity or population, and carbon dioxide evolution have all been used with success. 

Carbonates. Iron(II) carbonate [563-71-3] FeCO, precipitates as a white soHd when air-free solutions of alkah metal carbonates and iron(II) salts are mixed. The limited tendency of [Fe(H20)g] to hydroly2e is illustrated by the lack of carbon dioxide evolution in this reaction. The soHd rapidly... 

Ethylenediamine (15 g, 0 5 mol) was added dropwise to 100 ml 9B-100% formic acid in a two-necked 500 ml flask, fitted with an addition tube and reflux condenser with drying tube, cooled in an ice-bath. After complete addition of the base, 53 g of benzaldehyde (0.5 mol) was added in one lot. The ice-bath was removed and the flask was heated to the refluxing temperature. The initial rate of carbon dioxide evolution was too rapid to measure. After twenty minutes, the rate was circa 100 ml per minute and decreased rapidly to B ml per minute in one hour. Heating at reflux was continued for 35 hours. 

Table 11.3 Carbon Dioxide Evolution from FW Alkalinity...

Figure 3. Carbon Dioxide Evolution from Isothermal Decomposition of MDI at 225 °C.

Figure 4. Arrhenius Plot for Carbon Dioxide Evolution.

A full development of the rate law for the bimolecular reaction of MDI to yield carbodiimide and CO indicates that the reaction should truly be 2nd-order in MDI. This would be observed experimentally under conditions in which MDI is at limiting concentrations. This is not the case for these experimements MDI is present in considerable excess (usually 5.5-6 g of MDI (4.7-5.1 ml) are used in an 8.8 ml vessel). So at least at the early stages of reaction, the carbon dioxide evolution would be expected to display pseudo-zero order kinetics. As the amount of MDI is depleted, then 2nd-order kinetics should be observed. In fact, the asymptotic portion of the 225 C Isotherm can be fitted to a 2nd-order rate law. This kinetic analysis is consistent with a more detailed mechanism for the decomposition, in which 2 molecules of MDI form a cyclic intermediate through a thermally allowed [2+2] cycloaddition, which is formed at steady state concentrations and may then decompose to carbodiimide and carbon dioxide. Isocyanates and other related compounds have been reported to participate in [2 + 2] and [4 + 2] cycloaddition reactions (8.91. 

Capone, D.G., Reese, D.D., and Kiene, R.P., Effects of metals on methanogenesis, sulfate reduction, carbon dioxide evolution, and microbial biomass in anoxic salt marsh sediments, Appl Environ Microbiol, 45 (5), 1586-1591, 1983. 

A 7 year old screw capped sample burst in storage. Peroxide formation seems a less likely cause than slow hydrolysis and carbon dioxide evolution, though both are possibilities. 

The acid-oxidant method is based on the idea that the hydrolysis of cellulose might be continuously determined from the rate of carbon dioxide evolution. Since, under controlled conditions, the rate of evolution of carbon dioxide is proportional to glucose concentration, it should be possible to follow the course of cellulose hydrolysis by means of the rate of carbon dioxide evolution provided that the sole final product of hydrolysis of cellulose is glucose. The latter assumption appears to be justified where the sample is reasonably pure. 

The same series of hydrocelluloses was subsequently subjected to the carbon dioxide evolution test with the results shown in Fig. 3. These curves indicate that 4 minutes (.07 hr.) of prior hydrolysis caused an (26) G. F. Davidson, J. Textile Inst., 84, T87 (1943). 

By calculations based on differences in carbon dioxide evolution, it was found that about 3% of the intact linters structure was removed in. 07 hours of prior hydrolysis. Partial confirmation of these calculations was obtained experimentally when it was found that a mixture containing 97 % of. 07-hour hydrocellulose and 3.3 % of glucose simulated... 

B. 3-Cyclopentene-1 -carboxylic acid. A 250-mL, one-necked, round-bottomed flask is charged with 35.8 g of 3-cyclopentene-1,1-dicarboxylic acid and then fitted with a reflux condenser capped with a rubber septum and connected to a Nujol-filled bubbler by means of a syringe needle. The contents of the flask are heated in an oil bath at 170-175°C until carbon dioxide evolution is complete (ca. 2 hr) and then allowed to cool to room temperature. The resulting oil is transferred to a 50-mL flask and vacuum distilled without fractionation to provide 23.0 g (89% or 82% overall from dimethyl malonate) of 3-cyclopentene-1-carboxylic acid as a clear, colorless oil, bp 88°C (2 mm) (Note 7). 

P. Argyropoulos, K. Scott, and W. M. Taama. Carbon dioxide evolution patterns in direct methanol fuel cells. Electrochimica Acta 44 (1999) 3575-3584. 

Todd reported that the respiration of pinto bean leaves was stimulated by exposure to ozone (at 4 ppm for 40 min). The first measurements were 4 h after the ozone exposure. The respiration rate later declined to the control value. In all cases, increased respiration correlated well with visible injury. MacdowalP confirmed these results, but made an additional observation during the first hour after ozone exposure (at 0.7 ppm for 1 h), and before visible symptoms appeared, respiration was inhibited. The increase in respiration took place only later, when visible symptoms appeared. Dugger and Palmer" reported an increase in respiration in lemon leaf tissue after 5 days of exposure to ozone at 0.15-0.25 ppm for 8 h/day. They reported no morphologic changes at that time. Anderson and Taylor S found that ozone induced carbon dioxide evolution in tobacco callus tissue. The threshold for evolution was about 0.1 ppm for 2 h in the sensitive Bel W,. The ozone concentration required for maximal carbon dioxide evolution was about twice as much in the more resistant cultivar. Formation of roots decreased sensitivity. 

On, L.-T. and Street, J.J. Monomethylhydrazine degradation and its effect on carbon dioxide evolution and microbial populations in soil. Bull. Environ. Contam. Toxicol, 41(3) 454-460, 1988. 

The most fundamental work on polyethylene degradation is being done by A. C. Albertsson in Sweden(27,28,29,30,31) using elegant science with labelled polymers to measure the rate and quantity of carbon dioxide evolution from buried high and low density polyethylene films. Degradation occurs at about... 

Figure 2. Carbon dioxide evolution from films containing cornstarch, LDPE, and EAA during soil burial. Circles 13% (v/v) starch squares 20% starch trianges 28% starch. values were obtained by linear regression of time versus cumulative CO2 evolved.

In a 1-1. three-necked round-bottomed flask, wrapped with aluminum foil to exclude light, and equipped with a mechanical stirrer, a reflux condenser, and an addition funnel, is suspended 37 g. (0.17 mole) of red mercuric oxide (Note 1) in 330 ml. of carbon tetrachloride (Note 2). To the flask is added 30.0 g. (0.22 mole) of 3-chlorocyclobutaneearboxylic acid (Note 3), and the mixture is heated to reflux while stirring. To the mixture is added dropwise a solution of 40 g. (0.25 mole) of bromine in 180 ml. of carbon tetrachloride as fast as possible (4-7 minutes) without loss of bromine from the condenser (Note 4). After a short induction period, carbon dioxide is evolved at a rate of 150-200 bubbles per minute (Note 5). The solution is allowed to reflux until the rate of carbon dioxide evolution slows to about 5 bubbles per minute. This will usually take 25-30 minutes (Note 6). The mixture is then cooled in an ice bath, and the precipitate is removed by filtration. The residue on the funnel is washed with carbon tetrachloride, and the filtrates are combined. The solvent is removed by distillation using a modified Claisen distillation apparatus with a 6-cm. Vigreux column, and vacuum distillation of the residual oil gives 13-17 g. (35-46%) of... 

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