What might be a thought is to use a phosphorous screen and remove every other phosphor. If the phosphors were to vibrate at a low Hz, then they may make salt ions believe that they are dense concentrations of salt. If so, then salt should stay away from the filter as salt likes to evenly disperse in solute.
Any suggestions for testing would be welcome. While I am not able to pursue such an idea, someone who is interested in advancing desalination might be.