Effect of heavy metals on the stabilization of mercury(II) by DTCR in desulfurization solutions

摘要

Several heavy metals, including Cu~(2+), Ni~(2+), Pb~(2+), and Zn~(2+), were investigated in simulated desulfurization solutions to evaluate their interferences with Hg~(2+) during the reaction with dithiocarbamate type chelating resin (DTCR). Appropriate DTCR dosage and the effect of pH were also explored with respect to restoration of high Hg~(2+) precipitation efficiency and reduction of mercury concentrations. The experimental results suggested that increasing heavy metal concentration inhibited Hg~(2+) precipitation efficiency to a considerable extent and the inhibition order of the four heavy metals was Cu~(2+) > Ni~(2+) > Pb~(2+) > Zn~(2+). However, the coordination ability was closely related to the configuration and the orbital hybridization of each metal. In the cases of Cu~(2+) and Pb~(2+), increased DTCR dosage was beneficial to Hg~(2+) precipitation, which could lay the foundation of practical applications of DTCR dosage for industrial wastewater treatment. The enhanced Hg~(2+) precipitation performance seen for increasing pH might have come from the deprotonation of sulfur atoms on the DTCR functional groups and the formation of metal hydroxides (M(OH)_2,M = Cu, Pb, Hg).