Studies on the utilization of red mud for environmental application

The extraction of alumina from bauxite by Bayer's process is economical and most used process. In this process, bauxite is digested with excess of sodium hydroxide at elevated temperature and pressure. During the process, bauxite is converted in to soluble sodium aluminate and the insoluble component are called as 'red mud' or 'bauxite residue. The red color of the bauxite residue is due to the presence of high percentage of oxidized iron and thus termed as red mud. The pH of the red mud is in the range of 10.5-12.5 due to the presence of sodium hydroxide and change in the mineral composition of bauxite during Bayer's process. Besides iron oxide, the other major constituents of red mud are silica, alumina and titanium oxide. It is estimated that the red mud generation is in between 1-1.5 tones per tons of alumina produce. Because of alkalinity constituent and volume of red mud generated, it possesses a severe environmental lode. Extensive researches are going on throughout the globe for utilization of red mud. The thrust area of this research is to develop an adsorbent by modification of red mud and used for the removal of hazardous inorganic and organic species from water.