Model-based prediction and experimental validation of viscosities of soap emulsions Chapter uri icon


  • Soap is a very common end-consumer product which is used worldwide, with ten billion pounds produced per year. In Mexico, for example, the annual soap production industry is valuated 200. million dollars, making the soap production profitable. During the continuous saponification process, the emulsion viscosity is an essential variable which influences the conversion due to mass transfer limitations. Viscosity also impacts the operation of the downstream processing steps, such as the extrusion and the soap compression, to achieve the final product quality. Laundry soap emulsion viscosity prediction is complex due to the heterogeneous and variable composition: moisture, free sodium hydroxide, sodium chloride, sodium sulphate and fatty acids concentrations. Therefore, in this contribution the objective is to obtain a mathematical model via response surface methodology, to predict the emulsion viscosity for the system under study, which is the production of laundry soap in a facility located in Mexico: Jabonera Potosina. The methodology to develop such a model is the following: 1. Definition of the response property (viscosity). 2. Analysis of the variables that influence the viscosity: compounds concentrations, fat saponification value (FSV) and fatty acid value (FAV). 3. Determination of the ranges of the variables. 4. Creation of a response surface via a central composite design. 5. Performance of the experiments. 6. Analysis of the results, and 7.Model development. The obtained equation relates all the variables mentioned previously with the emulsion viscosity. This equation will be useful to identify the operational adjustments in the process for different scenarios, such as the change of product from laundry soap to toilet soap. © 2015 Elsevier B.V.

publication date

  • 2015-01-01