With respect to the indisputable use of the chemical method for estimating the total interfacial area, this critical survey of existing solutions of basic problems associated with successful applications of this method is presented. The influence of absorption rate on hold-up and total interfacial area in a mechanically agitated gas-liquid reactor, which has been hitherto neglected, was examined. Two model concepts were proposed concerning the flow of bubbles through the reactor in absence of coalescence. The absorption of pure oxygen in sodium sulphite solution in the presence of cobalt catalyst was used to verify the model concepts. The methods applied made it possible to measure the hold-up and the total interfacial area at various absorption rates. The absorption rate was changed by changing the catalyst concentration. The measurements were carried out for various agitator speeds and for various gas flow rates to the reactor. It was found that under certain conditions there is a significant decrease of the interfacial area and hold-up along with increasing absorption rate. Maximum decrease of the interfacial area experimentally found was about 70 per cent of that in the absence of absorption. The results were in good agreement with the model based on the concept of subreactors. The model predicts that the fractional decrease in the gas hold-up and interfacial area depends only on the relative amount of gas absorbed. The corresponding relations are: {A figure is presented} The deviations of experimental values from that predicted by the model did not exceed 10 per cent. The results were successfully used to account for some of the contradictions between the interfacial areas determined by the absorption of diluted and pure gas. The authors suppose that the relations derived are useful for other absorption devices as, e.g., reactor with perforated plate. © 1969.
