(A) study on the development of gentamicin separation process by foaming

Abstract

In order to develop a novel separation process and determine the feasibility of such a method for gentamicin, the foam separation technique was tested using a batch system. The model of separation mechanism for gentamicin was proposed, and based on this model, a theoretical rate equation was derived and compared with the experimental data. The effect of process variables ; surface active agent, pH, collector-colligend ratio, and gas flow rate on the separation efficiency were examined. First, four anion sufactants were tested as a collector, and among these sodium dodecyl sulfate showed the highest recovery yield. Below pH 9, the recovery of gentamicin was nearly constant, and above pH 9, gentamicin was not separated. This implies that below pH 9, gentamicin is fully ionized and it may be selectively adsorbed at the interface of gas bubbles in liquid by the ionic attraction. It was observed that the optimal collector to colligend ratio was three when the concentration of gentamicin was 100 g/ml. As gas flow rate increases the rate of separation is increased, while the enrichment ratio is decreased because of large entrained liquid solution in the foam phase. From the experimental results, the set of optimum conditions was selected as follows ; sodium dodecyl sulfate as a collector, at a pH lower than 9, collector to colligend ratio of 3, and 120 ml/min as gas flow rate. Under these optimal operating conditions, the recovery of gentamicin was 73% as an average value. The ion flotation mechanism of gentamicin was proposed and a model was set up based on the foam properties and the reaction mechanism. Using this model the separation rate equation was derived, which is similar to that of reversible first order reaction. This theoretical equation was well fitted to the experimental data. And finally, the effects of process variables on the separation rate were examined and discussed as a theoretical approach. The recovery effeciency of 73% by foam separation techniq...