The QDTL is a teaching unit that allows the students to familiarise with the notions of mass transfer theory, specially the diffusion in liquid systems, obtaining experimental data and results which are very useful for an ideal practice understanding of the process and consequently, for the technical teaching of the students.
The experimental determination of the diffusion coefficient D for a binary mixture, can be performed with a device such as the one AB described below.
A small volume tube with a filtering cell which has a certain number of pores has been placed at one of its ends. A concentrated solution of salt (sodium chloride) has been introduced inside. The tube is introduced in a vessel with pure solvent (distilled water). Now, the diffusion starts, and it will be indirectly measured by the conductivity data.
A thermostatic bath allows us to make the experiments at different temperatures.