Interphase mass transfer process

In the liquid-liquid extraction process, the mass transfer of the solute from one phase to the other is caused by the difference of the chemical positions of the solute in the two phases.

The process of mass transfer involves three steps:

(1) The solute is transferred from the main body of the extracted solution phase to the phase boundary;

2.. The solute passes through the interface from the extracted solution phase to the extractant phase.

3. The solute is transferred from the extractant phase boundary to the main body of the phase.

Mass transfer coefficient

The mass transfer process is complicated in the solid extraction equipment such as packing column, pulse sieve plate column and mixing and clarifying tank.

Fluid flowing through internal components such as packing and sieve plate will cause two high degrees of dispersion and strong turbulence, and the mass transfer process is very different from simple molecular diffusion. The actual contact area of the two phases is different from the geometric surface area of the packing column, and the total surface area of the droplets in the mixed clarifier and pulse sieve column is more difficult to estimate. In principle, the mass transfer rate can be estimated, but because the eddy diffusion coefficient and diffusion distance are difficult to measure and estimate, they cannot be used in engineering calculation in practice.