Equilibrium modified atmosphere

Jacxsens, L., Devlieghere, F., Falcato, P and Debevere, J. (1999) Behavior of Listeria monocytogenes and Aeromonas spp. on fresh-cut produce packaged under equilibrium-modified atmosphere . Journal of Food Protection, 62, 1128-1135. 

Jacxsens, L., Devlieghhere, F., and Debevere, J. Validation of a systematic approach to design equilibrium modified atmosphere packages for fresh-cut produce. Lebensmittel Wissenschofi und Technologie, 32, 425-432 (2000). 

The addition of H2O and CO2 to the fuel gas modifies the equilibrium gas composition so that the formation of CH4 is not favored. Carbon deposition can be reduced by increasing the partial pressure of H2O in the gas stream. The measurements (20) on 10 cm x 10 cm cells at 650°C using simulated gasified coal GF-1 (38% H2/56% CO/6% CO2) at 10 atm showed that only a small amount of CH4 is formed. At open circuit, 1.4 vol% CH4 (dry gas basis) was detected, and at fuel utilizations of 50 to 85%, 1.2 to 0.5% CH4 was measured. The experiments with a high CO fuel gas (GF-1) at 10 atmospheres and humidified at 163°C showed no indication of carbon deposition in a subscale MCFC. These studies indicated that CH4 formation and carbon deposition at the anodes in an MCFC operating on coal-derived fuels can be controlled, and under these conditions, the side reactions would have little influence on power plant efficiency. 

The maximum concentration of ozone in the stratosphere (or the ozone layer) is about 9 ppm at an altitude of about 35 km. That is, the concentration of ozone in the so-called ozone layer is still very low. Transport of ozone in the atmosphere modifies ozone concentration levels at each altitude and latitude. It is emphasized that the steady-state concentration of O3 in the stratosphere is not the thermodynamic equilibrium concentration, but is established by kinetics of photochemical reactions. 

Vapor-liquid equilibrium data at atmospheric pressure (690-700 mmHg) for the systems consisting of ethyl alcohol-water saturated with copper(II) chloride, strontium chloride, and nickel(II) chloride are presented. Also provided are the solubilities of each of these salts in the liquid binary mixture at the boiling point. Copper(II) chloride and nickel(II) chloride completely break the azeotrope, while strontium chloride moves the azeotrope up to richer compositions in ethyl alcohol. The equilibrium data are correlated by two separate methods, one based on modified mole fractions, and the other on deviations from Raoult s Law. 

Figure 7.13 Theoretical down-core profiles of radon activity illustrating that 222Rn is typically not in (a) secular equilibrium with its parent 226Ra at the sediment-water and water-atmosphere interfaces because of inert characteristics and loss by (b) diffusion and (c) gas bubble ebullitive stripping from sediments to overlying waters and then to the atmosphere. (Modified from Martens and Chanton, 1989.)...

Although ocean chemistry determines the CO2 concentration of the atmosphere in the long term and the solubility and biological pumps act to modify this long-term equilibrium, shortterm exchanges of carbon between ocean and... 

The hydrolysis of Alq3 was characterized with a gas chromatography and mass spectroscopy (GC-MS) apparatus modified with a headspace accessory designed to study volatile products evolved from solid materials (illustrated in Fig. 3.2, inset).41 Powder or film (deposited on foil) samples of Alq3 were held in a constant-temperature injection port for a given time, and the eluents at the end of the heating period were fed to the GC column. The relative areas of water and Hq peaks were used to measure the conversion (a typical trace is shown in Fig. 3.2). The prepurified Alq3 samples were allowed to absorb an equilibrium amount of water from the atmosphere, which occurred in about 3 min for the samples used.16... 

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