Definition - What does Hydrophilic mean?

Hydrophilic refers to having a strong affinity for water. Something that is hydrophilic is soluble in water and dissolves into water very easily. Hydrophilic is the opposite of hydrophobic.

Hydrophilic and hydrophobic surfaces both have important applications in all types of engineering, including:

  • Chemical
  • Automotive
  • Nautical
  • Industrial
  • Civil engineering

Hydrophilic substances can cause corrosion to metal surfaces and alloys.

Hydrophilic molecules are also known as polar molecules.

Corrosionpedia explains Hydrophilic

A hydrophilic molecule or portion of a molecule is typically charge-polarized and capable of hydrogen bonding, enabling it to dissolve more readily in water than in oil or other hydrophobic solvents. Hydrophilic substances can seem to attract water out of the air.

The hydrophilic concept is used in many industries. For example, hydrophilic membrane filtration is used in several industries to filter various substances such as:

  • Bacteria
  • Viruses
  • Particulates
  • Drugs
  • Contaminates

Hydrophilic coatings are particularly effective in environments of excessive condensation and to protect the exchanger from the corrosive effect of water. Hydrophilic coating also exhibits a fine performance in providing protection against water in high temperature and salty environments.

Since hydrophilic substances attract and hold moisture, it causes a molecular layer of moisture on the surface, which leads to corrosion. Hydrophilic substances like chlorides or sulfates promote corrosion by destroying surface film of metal or alloys. For example, the surface film that usually forms on magnesium alloys, is exposed to the atmosphere, and gives limited protection from further attack. Corrosion of magnesium alloys increases with relative humidity and contact with hydrophilic substances.

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