Experimental study on oxidation of elemental mercury by UV/Fenton system

In order to implement Hg-0 control strategy in a wet scrubber, oxidation of elemental mercury (Hg-0) in the simulated coal-fired flue gas by UV/Fenton system was investigated. Effects of different operation parameters have been studied, including initial solution pH, H2O2, TiO2 and Fe2+ concentration, solution temperature, gas flow rate and flue gas components (O-2, SO2 and NO). The main ion products in the solution have been analyzed. The experimental results suggested that oxidation of Hg-0 was inhibited with the increase of initial solution pH and gas flow rate. Additionally, with the increase of the H2O2, TiO2, Fe2+ concentration and solution temperature, the Hg-0 oxidation efficiency was enhanced to the maximum at first and then decreased. Hg-0 oxidation can be significantly inhibited by SO2 and NO when the flue gas was absence of O-2, but the oxidation capacity was recovered with 9% O-2 exist in the flue gas. SO2 showed an inhibition effect on Hg-0 oxidation, while the inhibition was weakened at higher SO2 concentration. Different NO concentration had an insignificant effect on Hg-0 oxidation process under the experimental conditions. In the case of presence and absence of flue gas components (9% O-2, 800 ppm SO2, 600 ppm NO) and under the optimal conditions (PH = 1, [H2O2] = 0.05 mol/L: [TiO2]= 0.6 g/L; [Fe2+]/[H2O2] 1/2; T = 40 degrees C), the average oxidation efficiency of Hg-0 can reach to 94.4% and 98.5%, respectively. (C) 2013 Elsevier B.V. All rights reserved.