Metal oxide nanoparticle-modified graphene oxide for removal of elemental mercury

ABSTRACT

Mercury is an extremely toxic element that is primarily released by anthropogenic activities and natural sources. Controlling Hg emissions, especially from coal combustion flue gas, is of practical importance in protecting the environment and preventing human health risks. In the present work, three metal oxides (MnO₂, CuO, and ZnO) were loaded on graphene oxide (GO) sorbents (designated as MnO₂-GO, CuO-GO, and ZnO-GO). All three adsorbents were successfully synthesized and were well characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the metal oxide nanoparticles (NPs) successfully decorated the GO. The elemental Hg adsorption capabilities of the three sorbents were subsequently evaluated using an in-house built setup for cold vapour atomic fluorescence spectrophotometry (CVAFS) with argon as the carrier gas for mercury detection. The testing temperature ranged from 50°C to 200°C at intervals of 50°C. MnO₂-GO showed an excel lent Hg⁰ adsorption capacity via chemisorption from 50 to 150°C and a mercury removal efficiency as high as 85% at 200°C, indicating that the MnO₂-NP-modified GO is applicable for enhancing gas-phase elemental mercury removal. However, neither CuO-GO nor ZnO-GO performed well. This work provides useful insights into the development of novel sorbent materials for the elemental mercury removal from flue gases.

GRAPHICAL ABSTRACT

KEYWORDS:

• Graphene oxide
• elemental mercury
• metal oxides
• nanoparticles
• efficiency

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful for the financial support from the Natural Sciences and Engineering Research Council of Canada, Hubei Provincial Natural Science Foundation of China [grant number 2018CFB337] and National Natural Science Foundation of China [grant number 51506066].