Removal of mercury in waste water using activated red mud

Abstract

Heat activated red mud was used to remove mercury ion (Hg2+) from water in this paper. The removal efficiency of red mud roasted at 400 to 900 °C for 4 to 10 h was measured. The structure of red mud samples which were activated under various temperatures was studied using XRD. The result showed that the samples roasted at 500 °C for 4 h had the highest adsorption capacity, 96.7 ng Hg g-1. Kinetic study showed that the adsorption process followed pseudo second order model while not pseudo first order model. The removal efficiency increased with pH in the range of 3.5 to 6.5 and decreased when pH was over 6.5. As heat could remove almost all of the mercury adsorbed onto activated red mud, the adsorbent could be regenerated times and regeneration did not decrease mercury removal efficiency.