Carbon dioxide evolution test

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). 

ISO 9439,1999, Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in an aqueous medium - Carbon dioxide evolution test International Standard ISO 9439 1999(E), International Oiganization for Standardization (ISO),... 

IS09439 1999 Water quality—evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium—carbon dioxide evolution test... 

ISO 9439 2000(E), Water Quality - Evaluation of Ultimate Aerobic Biodegradability of Organic Compounds in Aqueous Medium - Carbon Dioxide Evolution Test, International Organization for Standardization, Geneve, Switzerland, 2000. 

The biodegradation of EnPol polymers was tested in a controlled laboratory composting test and showed that within 45 days a carbon dioxide evolution of more than 90% of the carbon present in the co-polyester was detected. 

Biodegradation testing was done in the biometer described in Figure 3. The environments of choice were mixed with the plastic or degradation products and the rate and degree of carbon dioxide evolution measured by capture in the reservoir of caustic soda solution. 

Figure 3. Biometer for Measuring Carbon Dioxide Evolution in Biodegradation Testing.

Acidify the bicarbonate solution (aqueous extract), still in the separatory funnel, with 6 mL of 1 M sulfuric acid. This step should be performed without delay, to avoid hydrolysis of the aspirin. The acid must be added slowly in small portions. Mix well only after most of the carbon dioxide evolution has ceased. The pH at this point should be 1 to 2 (pH test paper). Extract the acidified solution with eight separate 10-mL portions of methylene chloride and filter through a methylene chloride-wet paper into a 100-mL volumetric flask. Dilute to volume. Then, dilute further a 5-mL portion of this solution to 25 mL with methylene chloride in a volumetric flask. 

The monitoring of carbon-14 labeled carbon dioxide evolution detected by scintillation counting is a very sensitive method but requires the expensive synthesis of radiolabeled test substrates. It is closely related to the ultimate degradation of the test material. H-PE is also used in biodegradation testing [121]. Rate of biodegradation is measured by CO2 production relative to that of compounds of similar chemical structure produced in nature which are known not to accumulate in the environment [117]. 

The rate of primary degradation is determined by measuring the level of intact surfactant in the sample as a function of time. Such an experiment is sometimes called a die-away test. For a system in which the surfactant provides the only nutrient source, as in a laboratory test cell, ultimate degradation can be determined by monitoring the level of total organic carbon. If the TOC concentration stabilizes at a level above zero, this indicates the presence of stable metabolites or impurities. Carbon dioxide evolution may be quantitatively monitored to give the same information. 

Nitrogen. To one portion of the filtrate, add z-3 ml. of 10, aqueous sodium hydroxide solution, then add about o-2 g. of ferrous sulphate and proceed as in the Lassaigiie nitrogen test (p, 322). Note, however, that the fiUal acidification with dilute siiphiiric acid must be made with care, owing to the vigorous evolution of carbon dioxide from the carbonate present. 

These equations tell us that the reverse process proton transfer from acids to bicarbon ate to form carbon dioxide will be favorable when of the acid exceeds 4 3 X 10 (pK, < 6 4) Among compounds containing carbon hydrogen and oxygen only car boxylic acids are acidic enough to meet this requirement They dissolve m aqueous sodium bicarbonate with the evolution of carbon dioxide This behavior is the basis of a qualitative test for carboxylic acids... 

During the development of this procedure, evolution of carbon dioxide was monitored with a wet-test meter. At the bath temperature given (160°), sodium chlorodifluoroacetate... 

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