Designing Bleaching Earths and Activated Carbons – the Science & Art

Dr Pat Howes, Technical & Marketing Director, NATURAL BLEACH SDN BHD

Bleaching earths and activated carbons are two of the most important adsorbents utilized for the removal of a wide range of impurities from oils, fats, waxes, etc. Each adsorbent has it own set of pros and cons, and each type of oil being refined has its own set of impurities that need to be reduced or removed. Science provides us with the knowledge of the physical and chemical properties of the adsorbents, and the art is how to create an adsorbent formulation that matches all the needs of the refiner. This paper will identify some of the key chemical and physical features of bleaching earths and activated carbons and discuss design philosophy to arrive at the most appropriate formulations for the material being refined.

Natural and acid activated clays as well as steam and acid activated carbons of several types will be discussed, together with the reasons for their selection. The beneficial utilization of spent bleaching earths will also be discussed as an additional factor influencing the adsorbent-system design process.