Fuller's Earth adsorbent is composed of which silicate?

• A. Magnesium aluminum silicate
• B. Sodium aluminum silicate
• C. Calcium aluminum silicate
• D. Potassium aluminum silicate

Answer: (A)

Fuller's earth works as an adsorbent because it’s a hydrous aluminosilicate clay with a layered silicate structure. Its adsorptive power comes from the presence of magnesium and aluminum in the silicate framework, making it a magnesium aluminum silicate. This composition gives high surface area and cation-exchange capacity, ideal for pulling impurities from oils and gases. Sodium, calcium, or potassium silicates are different types of silicate materials with distinct structures and cation content, so they don’t describe the composition typically associated with Fuller’s earth. Hence, the silicate in Fuller’s earth adsorbent is magnesium aluminum silicate.