Is mucus significantly affected by the presence of ions?
Yes.  Mucus is hydrated by the movement of ions.

Cells cannot move water.  Cells can only move ions, and water follows the osmotic gradient.  When hydrating mucus, cells move ions into the mucus and water follows.  A failure of this system is seen in cystic fibrosis.

Targeting ion channels in cystic fibrosis


  CFTR, the protein that is defective in cystic fibrosis (CF), directly
  mediates the transport of chloride and other anions through the apical
  membrane of several types of epithelial cells [1], [2]. Therefore,
  mutations impairing CFTR function cause a severe imbalance in ion and
  water transport that leads to a variety of negative effects in various
  organs. In the lungs, impaired secretion of chloride and bicarbonate
  appears to have multiple consequences. First, reduced secretion of
  electrolytes, and consequently of water, causes dehydration of airway
  surfaces with impairment of mucociliary clearance [3]...


People with cystic fibrosis have a defective chloride channel, and it cannot move chloride into mucus.  They therefore have thick mucus with abnormally low water content, and much of the trouble they have with their lungs is because this thick mucus does not perform its functions well.