The release of nitrogen compounds into the environment is a major concern worldwide. Different studies howed that recycled
materials have a high removal capacity for pollutants. Bentonite and its major clay minerals, smectites clays are common
bleaching agents used for oil refinery bleaching and known as bleaching earth (BE). In this study regeneration of spent bleaching
earth (SBE) acquired from the vegetable oil industry was surveyed via different methods and the regenerated spent bleaching
earth (RSBE) was used for ammonium ion removal from aqueous solution in batch experiment. The effects of pH, contact time
and initial ammonium ion concentration were determined and adsorption isotherms were also obtained. Our study shows that the
adsorption process follows the Freundlich adsorption isotherm and maximum removal efficiency of ammonium ion was 81%
obtained at pH=6 and 8g/L RSBE. The ammonium ion adsorption for RSBE was best fitted with pseudo-second order model. The
survey of adsorbent selectivity showed high selectivity toward ammonium ion.