Application of Mesopore-Activated Red Mud for Phosphorus Adsorption

In this paper, the mesopore-activated red mud (M-ARM) was prepared by treating red mud (RM) with acid under an ultrasonic batch and through heat treatment at 750 C. The surface area and adsorption average pore width of M-ARM were calculated and obtained values of 13.408 m 2 g -1 and 25.160 nm, respectively. Therefore, the maximum adsorption capacity of M-ARM for phosphorus was [Formula: see text] at 318 K and [Formula: see text]. At a low initial concentration (75 mg L -1 ), the phosphorus removal capacity by M-ARM material was up to [Formula: see text] at 313 K. With the temperature scales varying from 298 to 313 K, the values of Gibbs free energy change ([Formula: see text]) were negative and also vary from -37.47 to -36.68. The phosphorus adsorption process in an aqueous solution is spontaneous, and this adsorption process was exothermic with enthalpy change [Formula: see text]. From the results of investigations and calculations of thermodynamic values, kinetics, and adsorption capacity of materials, we can confirm that the materials in this study had a low-cost and potential material for applications to treat phosphorus-contaminated water. In addition, the adsorption kinetics of this material for phosphorus were also studied and discussed.