Hg0 oxidative absorption by K2S2O8 solution catalyzed by Ag+ and Cu2+

The aqueous phase oxidation of gaseous elemental Mercury (Hg-0) by potassium persulfate (K2S2O8, KPS) catalyzed by Ag+ and Cu2+ was investigated using a glass bubble column reactor. Concentrations of gaseous Hg-0 and aqueous Hg2+ were measured by cold vapor generation atomic absorption spectrometry (CVAAS). The effects of several experimental parameters on the oxidation were studied these include different types of catalysts, pHs and concentrations of potassium persulfate, temperatures, Hg-0 inlet concentrations and tertiary butanol (TBA). The results showed that the removal efficiency of Hg-0 increased with increasing concentration of potassium persulfate and catalysts Ag+. Cu2+ and Ag+ provided better catalytic effect than Cu2+. For example, in the presence of 5.0 mmol l(-1) KPS, the mercury removal efficiency could reach 75.4 and 97.0% for all Ag+ concentration of 0.1 and 0.3 mmol l(-1), respectively, and 69.8 and 81.9% for 0. 1 and 0.3 mmol l(-1) Cu2+. On the other hand, high temperature and the introduction of TBA negatively affect the oxidation. Furthermore, the removal efficiency of Hg-0 was much greater in neutral solution than in either acidic or alkaline solution. But the influence of pH was almost eliminated upon the addition of Ag+ and Cu2+, and high Hg-0 inlet concentration also has positive impact on the removal efficiency of Hg-0. The possible catalytic oxidation mechanism of gaseous mercury by KPS was also proposed. (c) 2008 Elsevier B.V. All rights reserved.