Solubilities of gases in aqueous solutions containing several components used in fermentation media

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Precise knowledge of the solubility of oxygen in fermentation media is very important for the process design and scale-up of bioreactors. A physical saturation method was applied to measure the solubilities of oxygen in fermentation media. The experimental apparatus consists of glass equilibrium cell,water bath,gas cylinder,vacuum pump,cooler and pressure gauge. The solubilities of oxygen were calculated from the pressure drop caused by contact between oxygen gas and liquid phases under equilibrium condition. The experimental results of oxygen solubility for pure water were compared with literature values in order to verify the experimental accuracy. The measurement of solubilities of oxygen was carried out for aqueous solution containing sodium chloride,ammonium sulfate,sucrose and their mixtures,dipotassium hydrogen-phosphate, patassium dihydrogenphosphate,glucose and maltose. Dipotassium hydrogenphosphate and potassium dihydrogenphosphate were chosen because they are important for potassium and phosphate sources and also used for buffers. Sugars are very important for carbon source and they have large salting-out effect for gas solubility. The measurements were carried out at 25,30 and 37ﾟC. These temperatures 30 and 37ﾟC are close to fermentation condition.The solubilities of oxygen were correlated by using the scaled-particle theory. By adjusting potential parameters,good correlation results were obtained.