Preferential wetting of tower material in spray columns for extraction

[plantprowler]

I was reading a section on Spray Columns used for Liquid-Liquid Extraction & it has a section that says:

"It is normal practice to select the phase that preferentially wets the internals of a tower as the continuous phase"


Given a carbon steel or stainless tower, how does one go about evaluating which phase would be the one preferentially wetting the tower internals? e.g. If you mix (say) Water & Toluene which phase preferentially wets the tower?

 

[mbt22]

In your example for say plastic internals that are reasonably hydrophobic/oleophilic, that rule of thumb would suggest the toluene as the continuous phase. Clean steel, there's probably not much in it.

If you need to measure wetting of a surface, it's done by contact angle measurement. If a droplet of your test liquid sits on the surface as a perfect sphere that is 180 degrees, with the other extreme of just spreading out flat on the surface giving 0 degrees.

Matt