Red mud was also used for the remov

Red mud was also used for the removal of fluoride from aqueous solution by C¸ engeloglu˘ et al.. They used both the original and activated red mud forms in batch mode and found that the adsorption capacity of activated form for fluoride was higher than that of original form. They further reported that the maximum fluoride removal occurred at pH 5.5. Red mud has also been used to remove phosphate (P) from aqueous solutions by Huang et al.. Acid and acid-thermal treatments were employed to treat the raw red mud. It was observed that the red mud with HCl treatment showed the highest adsorption capacity among all the red mud samples, giving adsorption capacity of 0.58 mg/g at pH 5.5 and 40 ◦C.