Characteristics and Inhibition of Hg0 Re-emission in a Wet Flue Gas Desulfurization System

Abstract

Characteristics of Hg0 re-emission in a wet flue gas desulfurization (WFGD) system were investigated on the basis of a bubble column. Five addition agents were used to inhibit Hg0 re-emission and improve removal of gaseous mercury. The results show that SO32– plays an important role in Hg0 re-emission in a WFGD system. Hg0 re-emission is intensified sharply in the presence of SO32– and further intensified with the increase of the SO32– concentration. Hg0 re-emission is strengthened at a higher temperature of desulfurization slurry. However, the removal efficiencies of both Hg2+ and total gaseous mercury decrease significantly with an increasing slurry temperature. The decreasing amplitude of total mercury removal efficiency is slightly higher than that of Hg2+. In addition, the re-emission rate of Hg0 declines first and then increases with an increasing pH value. A least Hg0 re-emission is observed at a pH value of 5.5. Fenton reagent, NaClO, K2S2O8, Na2S, and ethylenediaminetetraacetic acid (EDTA) can in...