Effect of Ammonium Ions on Structure of Bentonite and Hg~0 Removal Performance of Modified Bentonite

摘要

The Hg~0 removal performance of bentonite that was modified by ammoniumrnbromide and potassium bromide has been investigated in a laboratory-scale fixed-bedrnreactor. The sorbents have been characterized by the methods such as X-rayrndiffraction (XRD) and Thermo gravimetric Analysis(TG). The experimental resultsrnshow that Hg~0 removal performance of NH_4Br-Ben/Na sorbent is remarkable,rncompared with that of KBr-Ben/Na sorbent. Moreover, the highest Hg~0 removalrnefficiency of the NH_4Br-Ben/Na sorbent reached 94.3%; furthermore, it maintained atrna higher level for a long time, which indicates that the ammonium ions play a rolernduring the process of the oxidation between Br~- and Hg~0. Calcinations and solutionrnimpregnation are beneficial to the improvement of the mercury removal performancernof the sorbents. In the course of calcinations, the ammonium ions formed a relativelyrnstable material combining with bentonite within the layers which would contribute tornthe mercury removal.