Reaction oxygen level

Initiators, usually from 0.02 to 2.0 wt % of the monomer of organic peroxides or azo compounds, are dissolved in the reaction solvents and fed separately to the kettie. Since oxygen is often an inhibitor of acryUc polymerizations, its presence is undesirable. When the polymerization is carried out below reflux temperatures, low oxygen levels are obtained by an initial purge with an inert gas such as carbon dioxide or nitrogen. A blanket of the inert gas is then maintained over the polymerization mixture. The duration of the polymerization is usually 24 h (95). 

If the fire-refined copper is to be cast into anodes for electrorefining, the oxygen content of the copper is lowered to 0.05—0.2%. If the copper is to be sold directly for fabrication, the oxygen level is adjusted to 0.03—0.05%, which is the range for tough-pitch copper. The principal reactions of fire refining are... 

Similarly, when catalyzed the reaction rate decreases significantly as a function of pH level. The optimum reaction pH level is approximately 9.5 to 10.5. Iron, and especially copper, in the boiler may act as adventitious catalysts. However, as metal transport polymers are frequently employed, iron, copper, or cobalt may be transported away from contact with sulfite, and thus are not available for catalysis. (This may be a serious problem in high-pressure units employing combinations of organic oxygen scavengers and metal ion catalysts.)... 

The intrinsic kinetics of the reactions taking place in the scrubber, i.e. the reaction of NO with the iron chelate forming an iron nitrosyl complex (eq. 1) and the undesired oxidation reaction of the iron chelate (xanpla (eq. 2) wae deteimined in dedicated stirred cell contactors. Typical process conditions were T = 25-55 °C [Fe"(EDTA) "] = 1-100 mol/m [NO] = 1-1000 ppm pH = 5-8 and an oxygen level ranging between 1 and 20 vol%. 

Biochemical reactions must cater for living systems and as a result are carried out in an aqueous medium within a narrow range of conditions. Each species of microorganism grows best under certain conditions. Temperature, pH, oxygen levels, concentrations of reactants and products and possibly nutrient levels must be carefully controlled for optimum operation. 

Oxygen levels. Reactions can be carried out under aerobic conditions in which free oxygen is required or under anaerobic conditions in the absence of free oxygen. Bacteria can operate under aerobic or anaerobic conditions. Yeasts, moulds and algae prefer aerobic conditions but can grow with reduced oxygen levels. 

Photooxidation reactions of fluoroolefins in the presence of oxygen is one commercial method used in the production of PFPEs, generally employing either TFE or HFP. Fluorolefin concentration, oxygen level, light intensity, and temperature are all variables that have substantial impact on reaction rates, product distributions, polymer microstructure, peroxide content, and molecular weight. While HFP photooxidations are often carried out in bulk at low temperatures, TFE photooxidation must be carried out in an inert solvent, historically chlorofluor-ocarbons. 

The selection of the most appropriate mean treatment time, reaction temperature and dissolved oxygen level to be maintained in the aerated mixed liquor requires a clear definition of the treatment objectives for each particular farm enterprise. These are the... 

Samples of treated slurry were obtained from laboratory-scale continuous culture reactors (3 15 litres) during a series of treatments studying the effects on residual slurry quality of mean treatment time, reaction temperature, dissolved oxygen level and pH value (27). Some were also collected from a 2.4m3 pilot plant which was operating at 35°C and 7 day residence time and with dissolved oxygen saturation of 0 to 40%. The pilot plant was treating separated stored piggery slurry (TS 21 g/1 COD 26 g/1 ). 

Char oxidation dominates the time required for complete burnout of a coal particle. The heterogeneous reactions responsible for char oxidation are much slower than the devolatilization process and gas-phase reaction of the volatiles. Char burnout may require from 30 ms to over 1 s, depending on combustion conditions (oxygen level, temperature), and char particle size and reactivity. Char reactivity depends on parent coal type. The rate-limiting step in char burnout can be chemical reaction or gaseous diffusion. At low temperatures or for very large particles, chemical reaction is the rate-limiting step. At... 

Oxygen deficiency may result from the displacement of oxygen by another gas, or the consumption of oxygen by a chemical reaction. Confined spaces or low-lying areas are particularly vulnerable to oxygen deficiency and should always be monitored prior to entry. Qualified plant personnel should always monitor oxygen levels and should use atmosphere-supplying respiratory equipment [21]. 

When helium fusion begins, the core of the star is stabilised and a new spherical equilibrium is set up. Gravitational contraction is balanced by the expansive pressure of heat levels maintained by nuclear fusion reactions. Oxygen is produced to the detriment of carbon via the reaction... 

Since crushed basalt has been recommended as a major backfill component (1), experiments were completed to evaluate the rate of dissolved oxygen consumption and the redox conditions that develop in basalt-water systems under conditions similar to those expected in the near-field environment of a waste package. Two approaches to this problem were used in this study (l)the As(III)/As(V) redox couple as an indirect method of monitoring Eh and (2) the measurement of dissolved oxygen levels in solutions from hydrothermal experiments as a function of time. The first approach involves oxidation state determinations on trace levels of arsenic in solution (4-5) and provides an estimate of redox conditions over restricted intervals of time, depending on reaction rates and sensitivities of the analyses. The arsenic oxidation state approach also provides data at conditions that are more reducing than in solutions with detectable levels of dissolved oxygen. 

The fate of white phosphorus smoke is similar to the fate of reaction products of white phosphorus vapor in air. White phosphorus vapor in air reacts with oxygen and is changed to relatively harmless chemicals within minutes. However, particles in the air may have a protective coating that makes them unreactive for a longer time. White phosphorus reacts mainly with oxygen in water and may stay in water for hours to days. However, chunks of white phosphorus coated with protective layers may stay in water and soil for years if oxygen levels in the water and soil are very low. 

First flux estimates through larger parts of its metabolism were based on constraining assumed reaction networks with measurement of uptake and production rates [74]. A number of studies utilized stoichiometric balancing to assess the flexibility of the metabolic network [11, 75] and to investigate the influence of environmental conditions such as dissolved oxygen level [88], salt content [89], or nutrient status [12,90, 91]. However, this conventional approach cannot yield reliable information about parallel or bidirectional reactions and has to rely on balances for NADH or NADPH, which may not be accurate [34]. Moreover, it is limited to derive new conclusions since the results are strongly based on the taken assumptions and not on data [92],... 

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