DESCRIPTION

Technical Description

The CE 620 allows liquid mixtures to be separated using liquid-liquid extraction.

The liquid mixture to be separated is delivered from the feed tank into the bottom of the extraction column using a pump. There, it moves in counterflow towards the solvent, which is delivered into the top of the extraction column by a pump. The mixture to be separated is made up of a transition component and carrier liquid. The carrier liquid and the solvent are insoluble in one another and therefore a phase boundary is established in the column. This can be observed and can be adjusted using two valves. The movement of the transition component from the carrier liquid into the solvent occurs inside the column. Two three-way valves can be used to operate the trainer as a continuous or a discontinuous process.

A distillation unit facilitates the enrichment of the transition component in the extract. This consists of a heated round-bottomed flask with a packed column and a distillation bridge with Liebig condenser. The enriched extract leaves the column at the top and is collected in a tank. The bottom temperature is measured by a sensor, displayed digitally and controlled using a PID controller. The temperature at the top of the distillation column is also measured. Distillation removes the solvent from the transition component which is collected at the bottom of the unit and can be drawn off as a product. The separated solvent is collected in a tank and can be reused for extraction.

For a ternary material system, rapeseed oil is recommended as the carrier liquid with ethanol as the transition component and water as the solvent. For this ternary material system the concentrations of extract, top and bottom product are determined by measurement of density. A conductivity meter is included for alternative ternary material systems.

The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objectives / Experiments

- transition of a component from a two-component liquid mixture into a solvent by extraction
- scale-up from beaker experiment to pilot plant scale
- enrichment of transition component in extract by distillation
- evaluation of separation processes via concentration measurement and mass balances
- influence of different experimental options on separation processes