ETHYLENE-OXIDE SOLUBILITY AND ETHOXYLATION KINETICS IN THE SYNTHESIS OF NONIONIC SURFACTANTS

Solubility data from different sources of ethylene oxide in nonylpheno l, dodecanol, dodecanoic acid, and their related ethoxylated derivativ es have been interpreted by the authors with the UNIFAC, NRTL (nonrand om two-liquid theory), and Wilson methods. The results obtained with t hese methods have been compared. The two parameters of the NRTL and Wi lson equations have been correlated with the mean number of the ethyle ne oxide adducts of the hydrophilic chain by applying quadratic polyno mials. The Wilson equation give the best performances. The role of eth ylene oxide solubility in ethoxylation kinetics and mass transfer will be stressed. Kinetic and mass-transfer parameters are clearly correla ted with the ethylene oxide concentration. Therefore, the availability of more reliable solubility data or the use of a different method to represent these data requires the recalculation of kinetic parameters. This has been done for the three different substrates considered by a pplying the solubility data calculated with the Wilson equations. Smal l differences are observed in the kinetic parameters for dodecanol and dodecanoic acid with respect to previously published data, while rema rkable differences are observed for nonylphenol as a consequence of th e acquisition of more precise solubility data.