Fast and effective removal of elemental mercury in a wide temperature range is critical for the smelting industry. In this work, a recyclable magnetic iron sulfide/selenide sorbent is developed to capture and recover Hg 0 from smelting flue gas. Benefiting from Se doping, the Hg 0 capture performance of prepared FeS x Se y is significantly enhanced compared with traditional iron sulfide, especially at high temperatures. Considering the recyclability and working temperature, FeS 1.32 Se 0.11 exhibits the best Hg 0 capture performance. The average capture rate of FeS 1.32 Se 0.11 is 3.661 μg/g/min at 80 °C and its saturation adsorption capacity is 20.216 mg/g. The flue gas compositions have almost no effect on Hg 0 capture. X-ray photoelectron spectroscopy and mercury thermal programmed desorption suggest that the stable active Se−S n 2− adsorption site can combine with Hg 0 to form HgSe, consequently improving Hg 0 capture performance at high temperatures. After Hg 0 capture, the spent FeS x Se y can be collected by magnetic separation and regenerated through selective extraction, which facilitates harmless treatment and resource reuse of mercury. With the advantages of excellent Hg 0 capture performance, wide operating temperature range, and remarkable recycling property, FeS x Se y microparticles may be a promising sorbent for Hg 0 capture in industrial applications, while opening a new avenue to realize the resource utilization toward toxic elements.

Converting the NO from gaseous pollutant into NH through electrocatalytical reduction using cost-effective materials holds great promise for pollutant purifying and resources recycling. In this work, we developed a highly selective and stable catalyst CoSe nanoparticle hybridized with carbon nanotubes (CoSe@CNTs). The CoSe@CNTs hybrid catalysts performed an extraordinary high selectivity for NH formation in NO electroreduction with minimal NO production and H evolution. The specific spatial structure of CoSe is conductive to the predominant formation of N-H bond between the N from adsorbed NO and H and inhibition of N-N formation from adjacent adsorbed NO. It was also the first time to convert the coordinated NO into NH using non-noble metal catalysis. Moreover, the original concept of employing CoSe as eletrocatalyst for NO hydrogenation presented in this work can broaden horizons and provide new dimensions in the design of new highly efficient catalysts for NH synthesis in aqueous solution.

Fe(II)-EDTA, a typical chelated iron, is able to coordinate with nitric oxide (NO) which accelerates the rates and kinetics of the absorption of flue gas. However, Fe(II)-EDTA can be easily oxidized to Fe(III)-EDTA which is unable to absorb NO. Therefore, the regeneration of fresh Fe(II)-EDTA, which actually is the reduction of Fe(III)-EDTA to Fe(II)-EDTA, becomes a crucial step in the denitrification process. To enhance the reduction rate of Fe(III)-EDTA, selenium was introduced into the SO3 (2-)/Fe(III)-EDTA system as catalyst for the first time. By comparison, the reduction rate was enhanced by four times after adding selenium even at room temperature (25 °C). Encouragingly, elemental Se could precipitate out when SO3 (2-) was consumed up by oxidation to achieve self-separation. A catalysis mechanism was proposed with the aid of ultraviolet-visible (UV-Vis) spectroscopy, Tyndall scattering, horizontal attenuated total reflection Fourier transform infrared (HATR-FTIR) spectroscopy, and X-ray diffraction (XRD). In the catalysis process, the interconversion between SeSO3 (2-) and nascent Se formed a catalysis circle for Fe(III)-EDTA reduction in SO3 (2-) circumstance.

No abstract