nt for mass transfer. In this project liquid-liquid extraction was used to transfer benzoic acid from kerosene to water. Concentrations of the kerosene feed, extract, and raffinate were to be measured and used to find the number of theoretical stages and the height of equivalent theoretical stages (HETS) for the process. Concentration measurements will be made from samples of the feed, extract, and raffinate for two different steady state flow rates. Because the stirred column used in this experiment had not been used in several years this report will also include discussion of problems encountered in the experiment and possible solutions. Planning of the experiment will also be discussed. Careful planning was necessary because of the uncertainty of equipment, limited kerosene feed, and time constraints. A brief description of the apparatus and procedures used in this experiment will also be discussed. II. Theory.Liquid-liquid extraction is used to transfer one component between two immiscible liquids. This is possible because of the solubility of the component in both of the liquids. The component to be transferred is in solution with feed solvent. When this solvent comes into contact with extraction solvent the concentration gradient between the two solvents drives the component into the extraction solvent. If the two immiscible liquids were to have contact with each other for and infinite amount of time the three component system would reach equilibrium. In a liquid-liquid extraction column this would never happen because the column would need an infinite number of stages. Stages are used to determine the extent of mass transferred for a process. To determine the number of stages a graphical method found in Perrys Chemical Engineering Handbook (6th edition) can be used. When designing a liquid-liquid extraction column it is necessary to determine the number of theoretical stages needed for a specific separation....
