Neutralization of red mud using CO2 sequestration cycle.

A laboratory study was conducted to investigate the ability of neutralization of red mud (RM) using carbon dioxide gas sequestration cycle at ambient conditions. The neutralized red mud (NRM) was characterized by XRD, SEM, EDX, FT-IR and auto titration method. X-ray diffraction pattern of NRM was revealed that the intensity of gibbsite was increased prominently and formed ilmenite due to dissolution of minerals. EDX analysis was showed that the %(w/w) of Na, C, O, Si were higher in the carbonated filtrate as compared to the RM and NRM. The permanently sequestered CO(2)%(w/w) per 10 g of red mud were approximately 26.33, approximately 58.01, approximately 55.37, and approximately 54.42 in NRM and first, second, third cycles of carbonated filtrate, respectively. The pH of red mud was decreased from approximately 11.8 to approximately 8.45 and alkalinity was decreased from approximately 10,789 to approximately 178 mg/L. The acid neutralizing capacity of NRM was approximately 0.23 mol H(+)/kg of red mud. The specific advantages of these cyclic processes are that, large amount of CO(2) can be captured as compared to single step. 2010 Elsevier B.V. All rights reserved.