What types of oil purification exist?

There are several types of oil purification methods, including:

Filtration: Removes solid contaminants using fine filters.
Vacuum Dehydration: Uses vacuum pressure to remove moisture and dissolved gases from oil.
Centrifugation: Separates water, sludge, and solids from oil based on their density.
Adsorption: Uses adsorbents like clay or activated carbon to remove impurities and acids from the oil.
Chemical Treatment: Neutralizes acids and removes oxidation products using chemicals. Each method is selected based on the type of oil and the contaminants present.