Liquid Liquid Extraction

I was asked to extract benzoic acid from liquid - liquid extracted kerosene - benzoic acid mixture. This is done using a liquid-liquid extraction column which is stirred in a sophisticated laboratory. Fresh water is used as continuous phase in extraction. We were asked to measure the concentration of benzoic acid in the feed, raffinate and extract stream. These measurements are made at several different steady-state conditions. The number of theoretical phases and the theoretical phase height (HETS) are also determined.

In this experiment, liquid-liquid extraction was performed. This is also called solvent extraction and partitioning and is used to separate compounds based on their relative solubility in two different immiscible liquids (water and organic solvent). Extract substances from one liquid phase to another. Liquid-liquid extraction is the basic technology of a chemical laboratory using a separating funnel. Solvent extraction is usually done on a small scale by a laboratory chemist using a separatory funnel, which is usually done on an industrial scale using equipment that brings two liquid phases into contact with each other. Just to mention them, such machines include centrifugal contactors, thin layer extractors, spray columns, pulse columns and mixed precipitators.

Liquid-liquid extraction is very common in the industry and can be used to easily separate components which would otherwise be indivisible. This mass transfer operation utilizes the solubility of benzoic acid and the two immiscible liquids. Good contact surface area, contact time and appropriate solvent selection are important for mass transfer. In this project we convert benzoic acid from kerosene to water using liquid-liquid extraction. The concentrations of kerosene feedstock, extract and raffinate are measured and used to find the theoretical progression of the process and the height of the equivalent theoretical level (HETS). Concentration measurements were taken from samples of feed, extract and raffinate for two different steady state flow rates. Since the stirrer column used in this experiment has not been used for several years, this report will also explain the problems that occurred in the experiment and how to solve them. !