Introduction Of The Group Contribution Concept Into The Nrtl Model

Generally the NRTL activity coefficient model has shown great capabilities in predicting liquid-liquid or liquidvapour phase equilibria. However its major drawback is the non availability of the required molecular interaction parameters for a huge number of chemical systems. Therefore in the present work, a group contribution approach is introduced into the initial NRTL to give the GC-NRTL (Group Contribution NRTL) model. It is simply based on calculating group interaction parameters according to the NRTL equation, by minimizing an objective function made of the sum of the squared differences between the calculated values and the experimental ones reported in the literature. The minimization method is based on the Genetic algorithm which has proven to be very performing in reaching the optimum. As an illustration, the GCNRTL model was tested for 8 binary liquid- liquid systems mainly involving current functional groups like CH, CH2, CH3, OH, COOH, ACH, ACOH, ACCH3, NO, etc. The agreement between the predicted results by means of the GC-NRTL and the experimental phase equilibrium data is encouraging and the interaction parameters table should be completed to include a greater number of functional groups