Desorption of Mercury from Contaminated Soil Using Sodium Sulfite

Abstract

An effective reagent for mercury desorption from contaminated soil is a key condition for mercury remediation. Effects of time, pH, temperature on mercury desorption using sodium sulfite were studied with a series of batch experiments. Results showed that desorption rate of mercury increased rapidly in the stage of 0 to 1 h, after that, a much slower stage appeared. Desorption rate reached 92.05% with 0.7 mol/L sodium sulfite at 25°C in 24 h. Moreover, potential value increased rapidly from −162 to –31 mV in desorption of 1 h. It indicates that desorption process was a process of Hg(II) turning into Hg(I). A higher pH (10.5) or temperature (35°C) was helpful to increase mercury desorption rate. Furthermore, small fold and curves appeared in the surface of soil particles presented by scanning electron microscopy (SEM) show that soil particles may be destroyed in desorption process using sodium sulfite. The desorption of Hg from contaminated soil was accomplished within a reductive solution provided by sodium sulfite.

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