Nanosized Copper Selenide for Mercury Removal from Indoor Air and Emergency Disposal of Liquid Mercury Leakage

Abstract

Factories manufacturing mercury (Hg)-containing devices often outflow exhaust gas with a high concentration of Hg and face the risk of liquid Hg leakage. Herein, nanosized CuSe was prepared and employed for elemental mercury (Hg0) capture and the emergency disposal of liquid Hg from accidental leakage. CuSe exhibited an excellent Hg0 capture performance at room temperature. The Hg0 concentration could be efficiently reduced from 1500 to below 1 μg·m–3 under a gaseous hourly space velocity of 1.2 × 105 h–1. The adsorbent amount of CuSe was about 210.8 mg·g–1, which was about 219.5 times higher than that of a sulfur-functionalized activated carbon sorbent used exclusively for Hg0 removal. CuSe exhibited excellent adaptability at different temperatures and high-humidity surroundings. CuSe could effectively stabilize the leaked liquid Hg. The initial liquid Hg adsorption rate for CuSe was high, up to 69.1 μg·g–1·min–1, 138–2303-fold greater than that for other adsorbents reported in the literature. The impressive performance of CuSe for Hg0 immobilization was primarily attributed to the strong affinity of Se for Hg. The adsorption product of Hg (i.e., HgSe) exhibited sufficient thermal stability, which guaranteed the long-term storage of Hg-laden CuSe.

Toward an Understanding of Fundamentals Governing the Elemental Mercury Sequestration by Metal Chalcogenides

“…As a sulfo/selenophilic element, metal chalcogenides (MChals) were ideal natural traps for permanent Hg immobilization and sequestration. − With high affinity between sulfide (S 2– )/selenide (Se 2– ) and Hg, the transportation and conversion of Hg are pronouncedly controlled by forming cinnabar (HgS) or tiemannite (HgSe) as they are exceedingly resistant to environmental weathering. , Thus, HgS or HgSe is generally recognized as the final disposal of natural Hg and used as the ores for producing Hg 0 for decades. , Meanwhile, industries are simultaneously finding feasible techniques to capture and recycle Hg from domestic wastes and industrial emissions to achieve long-term sustainability, for which purpose the MChals were also ideal choices. − The Hg 0 enriched in daily consumables and industrial flue gases was adsorbed and immobilized by MChals as HgS or HgSe to mimic the natural Hg 0 stabilization processes, ,,, and the Hg-laden MChals can be used as recycled “Hg ores” to reproduce Hg 0 . ,, From this perspective, it is obvious that MChals are crucial linkages integrating the Hg 0 cycles worldwide, whose roles on the global Hg 0 behaviors are indispensable but, unfortunately, lack systematic understanding.…”

Density Functional Theory Study of Elemental Mercury Immobilization on CuSe(001) Surface: Reaction Pathway and Effect of Typical Flue Gas Components

“…This energy barrier was relatively low, and the conversion of Hg−Cu amalgam to HgSe could be approximated as spontaneous in Hg 0 capture at the optimal operation temperature (50 °C), 25 which can explain why no Hg−Cu amalgam could be detected in experiments in our previous studies. 25,46 Finally, the desorption energy for the final product, i.e., HgSe, was also obtained, reaching 205.8 kJ mol −1 , an extremely high energy barrier ensuring that HgSe was the destination for Hg 0 conversions over the CuSe surface. Thus, the HgSe as formed will accumulate on the sorbent surface and compromise the Hg 0 removal performance of CuSe until the external temperature is high enough to desorb HgSe.…”

“…The adsorption energy in this configuration reached −70.6 kJ mol −1 , representing a stable chemisorption and in line with experimental studies where HgSe was found to be the final product for Hg 0 adsorptions over CuSe. 46 Thus, the Cu-top site was more energetically favorable around the Se monomer and was chosen as the final state to further investigate the reaction pathway for Hg 0 adsorptions over the CuSe(001) surface.…”

“…The CuSe sample was prepared using the same hydrothermal method as reported in our previous study . Then, the CuSe as prepared was pretreated by Hg 0 with two reactors, i.e., a fixed-bed reactor and a nested-tube reactor, for which the details were described in our prior study .…”

“…The CuSe sample was prepared using the same hydrothermal method as reported in our previous study. 46 Then, the CuSe as prepared was pretreated by Hg 0 with two reactors, i.e., a fixed-bed reactor and a nested-tube reactor, for which the details were described in our prior study. 5 In the fixed-bed reactor, 1 mg of the CuSe sorbent was mixed with 499 mg of silicon dioxide (SiO 2 ) and pretreated with 100 μg m −3 Hg 0 carried by air at 50 °C for 30 min, and the as-obtained CuSe was called the Hg-laden sorbent.…”