Carbon Monoxide Consumption Research Articles

Production and consumption of carbon monoxide in a eutrophic lake1

CO concentrations were measured in the water of a eutrophic lake by a technique which allowed the detection of ⩾0.5 nl CO·liter−1 of water. In spring, when the lake was aerobic to the bottom, CO distribution was relatively homogeneous with concentrations of 40–130 nl liter−1. In summer, CO concentrations ranged between 20 and 615 nl · liter−1 in the aerobic epilimnion and metalimnion, but reached values of >8,000 nl · liter−1 in the anaerobic hypolimnion. CO increased during the morning and decreased during the afternoon in the upper water layers as well as in the dark hypolimnion. Incubation of lake water samples from different depths under daylight conditions resulted in a strong CO production. The light‐dependent CO production was stimulated by the high numbers of Oscillatoria rubescens in the metalimnion, but also by material from the lake sediment. Incubation of lake water samples in darkness resulted in CO consumption under both aerobic and anaerobic conditions.

Metabolism of Carbon Monoxide by the Colonic Flora of Humans

The metabolism of carbon monoxide by the colonic flora was investigated using human fecal homogenates. During anaerobic incubation, these homogenates rapidly consumed added carbon monoxide reducing the PCO level to a minimum of about 0.2 ppm. In the presence of glucose, carbon monoxide consumption averaged about 0.7 ml/h . g feces and without glucose about 0.2 ml/h . g feces. This consumption was not observed if the homogenates were autoclaved, passed through a bacterial filter, or cultured aerobically, indicating that the carbon monoxide was removed by the metabolism of fecal anaerobes. Aerobic incubation of fecal homogenates resulted in slow but definite release of carbon monoxide. While bacterial carbon monoxide consumption probably does not play an appreciable role in the turnover of carbon monoxide that is inhaled or exogenously produced, it is possible that carbon monoxide uptake by colonic flora protects other fecal organisms and possibly the host from carbon monoxide liberated in the gut.

Role of Carboxydobacteria in Consumption of Atmospheric Carbon Monoxide by Soil

The carbon monoxide consumption rates of the carboxydobacteria Pseudomonas (Seliberia) carboxydohydrogena, P. carboxydovorans, and P. carboxydoflava were measured at high (50%) and low (0.5 mul liter) mixing ratios of CO in air. CO was only consumed when the bacteria had been grown under CO-autotrophic conditions. As an exception, P. carboxydoflava consumed CO also after heterotrophic growth on pyruvate. At low cell densities the CO consumption rates measured at low CO mixing ratios were similar in cell suspensions and in mixtures of bacteria in soil. CO consumption observed in natural soil (loess, eolian sand, chernozem) as well as in suspensions or soil mixtures of carboxydobacteria showed Michaelis-Menten kinetics. The K(m) values for CO of the carboxydobacteria (K(m) = 465 to 1,110 mul of CO liter) were much higher than those of the natural soils (K(m) = 5 to 8 mul of CO liter). Considering the difference of the K(m) values and the observed V(max) values, carboxydobacteria cannot contribute significantly to the consumption of atmospheric CO.

Photooxidative production and microbial consumption of carbon monoxide in seawater by R. Conrad and W. Seiler

Photooxidative production and microbial consumption of carbon monoxide in seawater by R. Conrad and W. Seiler

Photooxidative production and microbial consumption of carbon monoxide in seawater

Photooxidative production and microbial consumption of carbon monoxide in seawater

Photooxidative production and microbial consumption of carbon monoxide in seawater

Photooxidative production and microbial consumption of carbon monoxide in seawater

Statistical study on the batch conversion of estevan lignite into oils using carbon monoxide and hydrogen mixtures

AbstractBatch autoclave hydrogenolysis of a Saskatchewan lignite has been conducted with CO and H2 mixtures. Conversion, oil yield and the carbon monoxide consumption patterns were measured as a function of reaction temperature (380 — 460°C), initial cold pressure (7.1 — 11.1 MPa), contact time (10 — 50 min), and initial CO/H2 gas composition (1/3 — 3/1 vol. %). The experimental results were obtained following an unreplicated 24 factorial design. Significant models were derived for conversion and the CO consumption patterns. A relationship seems to develop between carbon monoxide consumption and the amount of oil produced. The oil yield model however showed a lack‐of‐fit at the F5% level. The highest conversion and oil yield experimentally obtained were 85.3 and 63.4% respectively, on the lignite m.a.f. basis. In general greater hydrogenation but less deoxygenation occurred at the lower temperature.

Primary Zone Carbon Monoxide Levels for Gas Turbines Part I-Premixed Combustion

The analysis of the mechanism of the carbon monoxide (CO) production reveals that its formation is strongly dependent upon the local fuel/air ratio and the fuel breakdown rate. The consumption of CO is controlled by the reaction CO + OH «± CO2 + H. For premixed combustion, the temperature and the over-all rate of the combustion process are such that chemical equilibrium is attained within the primary zone residence times. Transient peak concentrations of CO, exceeding its equilibrium levels, occur for all pressure levels and fuel/air ratios over the range from rich to lean conditions. These peak CO levels appear to be proportional to the fuel/air ratio, while the final equilibrium CO levels and the fuel/air ratio relate in an exponential manner. The difference between the peak and the equilibrium CO level is largest for the lean high pressure cases. Hence, the utilization of lean combustion to reduce the CO levels may be hindered by inadvertent quenching of the peak CO levels, e.g., within the cooling layer.

Carbon Monoxide and Nitric Oxide Consumption in Polluted Air: The Carbon Monoxide-Hydroperoxyl Reaction

A recent laboratory measurement of the ratio of the rate constant for the reaction CO + HO (2) --> C0(2) + OH relative to that for H + HO(2) --> 2OH indicates that the former reaction is probably faster than CO + OH --> CO(2) + H. On this basis a simple analysis is given showing that the calculated lifetime of nitric oxide in polluted atmospheres would be appreciably longer than that estimated on the assumption that the carbon monoxide-hydroperoxyl reaction may be neglected. A fast carbon monoxide-hydroperoxyl reaction implies that the cyclic consumption of carbon monoxide (an atmospheric sink) could occur even with no nitric oxide present.

Structure analysis of counterflow diffusion flames in the forward stagnation region of a porous cylinder

An experimental study was made of the structure of the laminar counterflow diffusion flame established in the forward stagnation region of a porous cylinder. Aerodynamic, temperature, and stable-species-concentration profiles were measured in detail for methane flames at atmospheric pressure. These distributions were analyzed to yield the reaction-rate profiles of stable species and the heat-release-rate profile throughout the flame zone. Results show that, although the maximum concentrations of various intermediate products are observed between the luminous reaction zone and the stagnation point, various chemical reactions, including generation and consumption of such intermediate products, occur in the comparatively narrow region in and around the luminous reaction zone. The maximum rates of consumption of carbon monoxide and generation of carbon dioxide are found on the air side of the flame, and reaction-rate profiles of various stable species are qualitatively similar to those for the two-stage reaction in premixed hydrocarbon-air flames. The comparatively large convection velocity across the flame zone plays an important role, yielding the unique concentration profiles throughout the flame zone. The heat-release-rate profile shows a small valley (negative value) on the fuel side of the major peak, which is attributed to pyrolysis-type reactions. Two kinds of blowoff mechanisms of the present counterflow diffusion flame—namely, thermal quenching of the flame and chemical limitations on the combustion rate—can be clearly explained.