Adsorption removal of phosphate from aqueous solution by active red mud

Abstract

Abstract Red mud is the waste of alumina industry and has high TiO 2 and Fe 2O 3 content which are active components for the adsorption of anion pollutants. In this study, the uptake of phosphate by red mud activated by heat treatment and acid-heat treatment was investigated. The factors influencing the adsorption were also investigated. The result showed that the red mud sample treated using acid-heat method at 80°C with 0.25 mol/L HCl for 2 h achieved the highest phosphate removal. For the heat-activated red mud, the sample heated at 700°C for 2 h preformed better than the other heat treatment. Phosphate removal by the activated red mud was significantly pH dependent, and pH 7 was the optimal pH for phosphate removal. The adsorption fits Langmuir isotherm model well and the maximum adsorption capacities of the acid-heat activated red mud and the heat activated samples were 202.9 mgP/g and 155.2 mgP/g, respectively.