Study On Extractants Design With Computer Optimization Method

A novel strategy for designing extractants by computer optimization design method was presented. It was composed with the computer-aided molecular design and computer optimization screening method. The chain compounds, compounds ring and mononuclear aromatics were designed by combining Mod.UNIFAC group contribution method with modified genetic algorithm. And the obtained extractants were estimated by the computer optimization screening method. The accuracy of the method was verified by determining the infinite dilution activity coefficient of the water + acetic acid system in the superior extractants by gas-liquid chromatography method.A method based on the improved genetic algorithm for the computer-aided molecular design for extractive distillation was presented. A number of enhancements had been comprised. In order to greatly enhance the algorithm performing efficiency, a new encoding scheme was developed. Groups were represented by their own group number, and the molecular structure was described by string figures. To prevent the random errors of selecting molecule by roulette wheel rules and losing good solutions in generation reproduction, a cross generation elitist selection method was used. Dislocation crossover was developed to make molecules keep good diversity, and overcame the unfavorable defect of traditional crossovers which caused GA get into prematurely. In this work, mutation operator was just used if the algorithm almost achieved constringency stage. Here mutation was used to disturb the population and do make improvement.In order to estimate the obtained extractants comprehensively, a model for the comprehensive judgment of extractants in which eight factors including selectivity, solvent power, boiling point, molecular weight, viscosity, specific heat capacity, toxicity and corrosion were considered. And two groups of weights were allocated to assessment factors, and the weights were chosen by the user to suit the specific problem.The extractants of acetone+ methanol system and ethanol+ ethyl acetate system...