Removal of Hg0 with sodium chlorite solution and mass transfer reaction kinetics

Abstract

The absorption behavior of Hg0 was studied experimentally by using sodium chlorite solution (NaClO2) as the absorbent in a bubble reactor. Primary influencing factors on removal efficiency of Hg0 such as NaClO2 concentration, pH, reaction temperature and the concentration of Hg0 were investigated. The results indicated that 72.91% of Hg0 removal efficiency could be achieved in acidic NaClO2 solution. The removal mechanism of Hg0 was proposed by analyzing of Hg2+ concentration in absorption solution after reaction and comparing the electrode potentials between NaClO2 species and Hg2+/Hg0. The experimental results of mass transfer-reaction kinetics on oxidation of Hg0 by NaClO2 solution showed that with the increase of NaClO2 concentration and the decrease of pH value, the enhancement factor (E) and ratio of KG(Hg0)/kG(Hg0) increased and the liquid phase mass transfer resistance decreased, which is benefit to the mass transfer adsorption reaction. Although the increase of reaction temperature could improve the enhancement factor (E), but the ratio of KG(Hg0)/kG(Hg0) decreased; as a result, the liquid phase mass transfer resistance increased, therefore, the reaction rate for removal of Hg0 decreased.