Stabilization of mercury-containing wastes using sulfide

Abstract

This paper summarizes the findings of our studies on mercury stabilization using sulfide. Primary stabilization variables such as stabilization pH and sulfide/mercury molar ratio were tested. Mercury stabilization effectiveness was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) and the constant pH leaching tests. The influence of interfering ions on mercury immobilization was also tested. The experimental results indicate that the sulfide-induced treatment technology is an effective way to minimize mercury leaching. It was found that the most effective mercury stabilization occurs at pH 6 combined with a sulfide/mercury molar ratio of 1. The combined use of increased dosage of sulfide and ferrous ions ([S]/[Hg]=2 and [Fe]/[Hg]=3 at pH=6) can significantly reduce interferences by chloride and/or phosphate during sulfide-induced mercury immobilization. The sulfide-treated waste stabilization efficiency reached 98%, even with exposure of the wastes to high pH leachants.

Ecological strategy for soil contaminated with mercury

“…The most popular remediation technologies for mercury contaminated soils are: liquid extraction, thermal treatment, electrolytic methods, mercury flotation or immobilisation and solidification/stabilisation (S/S). Some of the S/S technologies are based on Hg stabilisation and solidification with sulphur polymer cement, thiolfunctionalised zeolite compounds and alkali sulphide (Fuhrmann et al 2002;Piao and Bishop 2006;Bower et al 2008;Zhang et al 2009). These technologies are expensive, complex processes that are destructive for soil organisms and of limited application in soil treatment (Wang et al 2012;Randall and Chattopadhyay 2013).…”

In situ remediation technologies for mercury-contaminated soil

“…HgS is a stable and insoluble compound with a solubility product of 2.0×10 −49 in water (Wagh et al 2000) and Hg can be considered immobilized when complexed with sulfide. Piao and Bishop (2006) studied the effectiveness of mercury stabilization with sodium sulfide using a laboratory-simulated mercury surrogate (sand spiked with mercuric nitrate) and a real mercury waste from contaminated sediment at a Superfund site. Both contained >260 mg kg −1 total mercury.…”

Recovery of Mercury from Spent Fluorescent Lamps via Oxidative Leaching and Cementation

“…The high efficiencies for mercury recovery from spent fluorescent lamps were reported using processes such as thermal desorption (pyrometallurgical) (Fujiwara and Fujinami 2004;US EPA 2007;Durão et al 2008;Chang et al 2009), chemical leaching (hydrometallurgical) (Klasson et al 1998;Jang et al 2005;Tunsu et al 2014), and stabilization/ solidification (Piao and Bishop 2006;US EPA 2007;Wang et al 2012). The main goal of these processes is the removal of mercury from the lamps, converting it into less toxic chemical compounds or recovering it as metal in its pure state.…”