PHOSPHATE REMOVAL POTENTIAL OF APPLYING RED MUD DERIVED FROM BAUXITE CALCINATION METHOD FOR WATER CLEANUP

摘要

In this study, the red mud derived from bauxite calcination method (RM_C), which differs from the traditional production in Bayer process (RM_B), was employed as an adsorbent to remove phosphate from aqueous solution. The uptake of phosphate onto RM_C strongly depended on the initial pH (pH_i), and the optimum value was found at 2.0. Kinetic studies indicated that the adsorption process followed well pseudo-second order model. The maximum adsorption capacity obtained from Langmuir model was 157.23 mg/g at 25 ℃. The negative value of thermody-namic parameter (AH) confirmed an exothermic reaction for phosphate adsorption by RM_C. The final pH value (pH_f) under the optimum pH_i was detected around 7.0 implying that the alkalinity of RM_c was balanced out, and the solution was a favorable acid-base condition for direct discharge. Moreover, it exhibited the same performance of phosphate adsorption capacity as activated RM_B by acidification and heat treatment. Thus, RM_C can be used as a potential adsorbent for phosphate removal in water cleanup.