A Nanoselenium Sponge for Instantaneous Mercury Removal to Undetectable Levels

Abstract

Selective removal of aqueous mercury to levels below 10 ng L−1 or part per trillion remains an elusive goal for public health and environmental agencies. Here, it is shown that a low‐cost nanocomposite sponge prepared by growing selenium (Se) nanomaterials on the surface and throughout the bulk of a polyurethane sponge exhibits a record breaking‐mercury ion (Hg2+) removal rate, regardless of the pH. The exposure of aqueous solutions containing 10 mg L−1–12 ng L−1 Hg2+ to the sponge for a few seconds results in clean water with undetectable mercury levels (detection limit: 0.2 ng L−1). Such performance is far below the acceptable limits in drinking water (2 µg L−1), industrial effluents (0.2 µg L−1), and the most stringent surface water quality standards (1.3 ng L−1). The sponge shows a unique preference for Hg, does not retain water nutrients, and can significantly reduce the concentration of other heavy metal pollutants. Furthermore, the sponge shows no cytotoxic effect on human cells while exhibiting strong antimicrobial properties. The high affinity of Hg for Se results in irreversible sequestration and detoxification of mercury by the sponge, confirming the suitability for landfill disposal.

Effective removal of mercury from aqueous streams via electrochemical alloy formation on platinum

“…Over 75% of the mercury was retrieved in one day (Fig. 1b ), and the efficiency was over 99% after 171 h. This corresponds to 0.35 µg L −1 mercury left in solution, which is well below the acceptable limit in drinking water 14 , 32 . We correlate this with the aforementioned slower inward metal inter-diffusion of mercury once several layers of alloy are formed.…”

“…In recent years, other approaches to remove mercury from aqueous streams have been suggested and evaluated 14 – 18 . Among them is the incorporation of mercury ions in a solid and stable metallic alloy, which is afterwards removed from solution.…”

Nanosized Copper Selenide Functionalized Zeolitic Imidazolate Framework‐8 (CuSe/ZIF‐8) for Efficient Immobilization of Gas‐Phase Elemental Mercury

“…However, the binding affinity constant of mercury selenide was one‐million‐fold higher than that of mercury sulfide, while the solubility of the mercury selenide was thousands‐magnitude‐levelly lower . As expected, the equilibrium adsorption capacity of Hg 2+ reached around 0.6 g Hg 2+ g −1 nano‐Se sponge as reported in previous study,[10a] which is much higher than that for MSs. However, it should be noticed that the nano‐Se was well supported on sponge with large surface area.…”

“…The as‐formed HgSe was proven to exhibit thousands‐magnitude‐levelly lower solubility compared with that of HgS. [10a] The antioxidant nature of the HgSe also prevents against the mercury neurotoxicity . Moreover, we conducted a leaching experiment to simulate the mercury leaching when the Hg‐laden CuSe‐based sorbents were dumped in environment (shown in Table S4, Supporting Information).…”

Rapid, Selective Heavy Metal Removal from Water by a Metal–Organic Framework/Polydopamine Composite

“… 41 , 42 It should be noted that Ahmed et al recently reported a nanoselenium sponge that also removes Hg 2+ in seconds. 43 However, they use 30 times more material, and while the nanoselenium sponge does irreversibly bind mercury allowing for easy disposal if used for in-home treatment, 44 , 45 this characteristic might limit its use in wastewater treatment. For Pb 2+ , the fastest material observed, to date, is a porous polymer, mPMF (mesoporous polymelamine-formaldehyde), that reportedly gets below the EPA limit also in seconds; however, the capacity for this material is extremely low, 0.628 mg of Pb 2+ /g, requiring large amounts of sorbent to achieve the same performance as Fe-BTC/PDA ( Table S4 ).…”