Impacting Factors of Elemental Mercury Re-emission across a Lab-scale Simulated Scrubber

Abstract

Elemental mercury (Hg 0) re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber. Oxidized mercury (Hg 2+) standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg 2+ in the flue gas across wet flue gas desulfurization (WFGD) systems. PS analytical mercury analyzer was used to continuously determine Hg 0 re-emission concentrations in the carrier gas from the scrubber. Sulfite ion in the slurry of CaSO 3 was validated to reduce Hg 2+ to Hg 0, while no Hg 0 re-emission occurred from slurries of CaSO 4 and CaO. Transitional metal ions with low chemical valence such as Fe 2+, Pb 2+, Ni 2+, and Cu + were used to prepare solutions with concentration levels of mmol·L −1. Reduction reaction of Hg 2+ to Hg 0 was observed from these solutions. Reduction capabilities for the different transitional metal ions in the solutions were: Pb 2+>Cu +>Fe 2+> AsO − 2>Ni 2+.