Oxidation Absorption of Hg-0 in the Gas Phase Using a Double Catalyzers-Double Oxidants Coactivation Technology

An oxidation absorption technology of Hg-0 in the gas phase using double metal catalyzers-double oxidants coactivation was developed. Several experiments were performed to study the main influencing factors, key reactive species, oxidation products, and mechanism of Hg-0 oxidation absorption. It was found that higher concentration of Fe2+ and Cu2+ led to an increase in Hg-0 removal efficiency. The removal efficiency of Hg-0 was declined through increasing the reagent pH value, flue gas flow rate, Hg-0 inlet concentration, and inlet content of NO/SO2. Changing the removal temperature and concentrations of PMS (peroxymonosulfate) and H2O2 resulted in a dual influence on Hg-0 oxidation absorption. Under the optimized experimental conditions, the maximum removal efficiency of Hg-0 is up to 97.5%. Due to the significant synergistic activation effect, bigger reactive species yield and higher Hg-0 removal efficiency were obtained in the double metal catalyzers-double oxidants coactivation system than those in the other contrasted systems, which were caused by the redox cycling by double metal catalyzers and the free radical capture intermediate formed between double oxidants. The Hg-0 oxidation absorption was mainly achieved by the oxidation of (OH)-O-center dot and SO4-center dot, and Hg2+ was confirmed to be the main products of Hg-0 oxidation absorption in the developed coactivation system.

Automated summary

An oxidation absorption technology using double metal catalyzers and double oxidants coactivation was developed for Hg-0 in the gas phase. The study found that higher concentrations of Fe2+ and Cu2+ increased the removal efficiency of Hg-0. The removal efficiency decreased with increasing pH value, flue gas flow rate, Hg-0 inlet concentration, and content of NO/SO2. Changing the removal temperature and concentrations of PMS and H2O2 had a dual influence on Hg-0 oxidation absorption. Under optimized conditions, the maximum removal efficiency of Hg-0 reached 97.5%. The developed coactivation system showed higher reactive species yield and Hg-0 removal efficiency compared to contrasted systems, mainly due to redox cycling by double metal catalyzers and the formation of free radical capture intermediate between double oxidants. The oxidation absorption of Hg-0 was mainly achieved through the oxidation of (OH)-O-center dot and SO4-center dot, with Hg2+ confirmed as the main product.