(2022) Journal of Environmental Chemical Engineering_Catalytic bromate reduction in water by Ru/C via borohydride-based hydrogenation: A comparative study

Chen W.-C., Kwon E., Bui H.M., Khiem T.C., Sirivithayapakorn S., Ghanbari F., Tuan D.D., Lin K.-Y.A.

(Elsevier Ltd) Journal of Environmental Chemical Engineering ISSN: 22133437 Vol.10 Issue.4 Article No.108080 DOI: 10.1016/j.jece.2022.108080

While H₂gas is conventionally purged during hydrogenation of bromate in the presence of catalysts, the low solubility of H₂gas leads to wasteful consumption of H₂gas. Reductants in solid forms, which act as storage media of H₂, would be preferable, and borohydrides, including NaBH₄, and NH₃BH₃are promising candidates. Although ruthenium (Ru) is an efficient catalyst for releasing H₂from these borohydrides, almost no studies have looked into usage of Ru with borohydrides for reducing bromate, and differences between NaBH₄, and NH3BH3for reducing bromate in the presence of Ru. Therefore, the goal of this study aims to compare hydrogenation of bromate using different borohydrides as well as H₂gas purge under different conditions in the presence of Ru/C as the most representative Ru catalyst. While Ru/C could slowly reduce bromate to bromide, the addition of NaBH₄or NH₃BH₃would tremendously accelerate bromate removal and bromide production. Nevertheless, the H₂purge might cause interferences with the entire reaction, thereby leading to ineffective bromate reduction. Moreover, Ru/C+NaBH4would lead to an even faster bromate reduction because adsorption of BH₄-to Ru/C was much more favorable according to the DFT calculation. The Eaof bromate reduction by Ru/C+NaBH₄is also lower than that by Ru/C+NH₃BH₃, validating the promising advantage of NaBH₄over NH₃BH₃. Ru/C+NaBH₄could be also reusable for reducing bromate to bromide, demonstrating that borohydrides might be promising alternatives to H₂purge for reducing bromate to bromide in order to achieve even faster and more efficient bromate reduction. © 2022 Sociedad Espanola de Ceramica y Vidrio. All rights reserved.

This project has been supported by Research Center for Environmental Contaminants (RCEC), Abadan University of Medical Sciences (Iran) under Contract No. 1400RCEC1426 .