Purification from oxidation involves:

Adsorption: Using materials like activated alumina or clay to remove oxidation products.
Chemical Treatment: Adding antioxidants or neutralizing agents.
Filtration: Removing insoluble oxidation byproducts.
Vacuum Distillation: Separating oxidized components under reduced pressure.
These processes restore the oil’s properties, extending its usability and protecting equipment from corrosive damage.