Hamidreza Gharibi - Water and Environmental Engineering Faculty, Shahid Beheshti University
Abolghasem Alighardashi - Water and Environmental Engineering Faculty, Shahid Beheshti University
Shahram Raygan - School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran
Abbas Akbarzadeh - Water Research Institute, Ministry of Energy

Red Mud (RM) is a solid industrial waste remains from Bayer's process to produce of alumina from Bauxite ore. Annually, about 60 million tons of RM is produced all over the world that may cause serious danger for environment (due to its high alkalinity). RM has found many applications in science andindustry e.g. production of color bricks, ceramics, cement, and adsorbents. Application of RM for environmental friendly purposes e. g. removal of heavy metal ions, inorganic anions, organics, dyes and pathogens from aqueous solution, have been widely developed recently. In this paper, process of nitrateadsorption on surface of RM adsorbent is discussed. Laboratory batch experiments conducted to study removal behavior of adsorbent under different pH solution conditions. The results show that increasing or decreasing in pH of solution, may result in reduced nitrate removal capacity. Optimum pH of adsorptionwas in range of natural water (pH=6.5). FT-IR test also implemented to investigate characteristics of RM adsorbent (before and after adsorption process). It shows that adsorption process obeys both physical and chemical procedure. Finally, Ligand-Exchange process on hydroxylated surface is supposed as the main process of nitrate ion adsorption on RM

Red Mud, Nitrate, Adsorption, Ligand-Exchange Process, Water Treatment