Neutralization of Red Mud Using CO2 Sequestration Cycle

Abstract

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 CO2 %(w/w) per 10 g of red mud were ~26.33, ~58.01, ~55.37, and ~54.42 in NRM and first, second, third cycles of carbonated filtrate, respectively. The pH of red mud was decreased from ~11.8 to ~8.45 and alkalinity was decreased from ~10,789 to ~178 mg/L. The acid neutralizing capacity of NRM was ~0.23 mol H+/kg of red mud. The specific advantages of these cyclic processes are that large amount of CO2 can be captured as compared to single step.