Study on the elution mechanism of HgO on mercury-loaded adsorbent in KCl solution via temperature programmed desorption (TPD) method

Abstract

MnTi adsorbent prepared by precipitation method was used to remove elemental mercury in pure nitrogen atmosphere, and TPD method was employed to investigate the mechanism of mercury elution from mercury-loaded MnTi adsorbent in KCl solution. In the gas-phase mercury adsorption process, the MnTi adsorbent removed mercury with a high efficiency of 50% under pure nitrogen atmosphere. The effects of stirring time, eluent concentration, and pH on Hg elution efficiency were evaluated in the liquid-phase Hg elution process. Mercury elution was assisted by adequate stirring time and eluent concentration. The pH value of the environment influenced mercury elution, with an acidic environment being more effective for mercury oxide elution. According to the experimental results, the highest mercury elution efficiency of 0.5 M KCl solution was 79%. The active chlorine produced during the elution process was valuable for reuse. The mercury removal performance of the reused MnTi adsorbent was not significantly different from that of the fresh adsorbent. The elution mechanism of HgO was also proposed, with the key link being the reaction of HgO(red) in solution with excess Cl− to form [HgCl4]2− complexes, which then entered the liquid phase. It was possible to conclude that KCl solution had a high potential for mercury elution from mercury-carrying adsorbents and waste adsorbent reuse.