Activated Bleaching Clay or Fullers Earth is used for decolarization. Bleaching of edible oils is essentially a selected adsorption of coloring matter and other impurities on exposed solid surfaces in contact with the liquid to be decolorized. Bleaching Earths provide the large surface areas effectively by virtue of their structure, history of formation  and activation. Bleaching earth are made by Acid Activation of Bentonites.